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1.
粗壮女贞中的新单萜配糖体   总被引:1,自引:0,他引:1  
从粗壮女贞(Ligustrum robustum)叶子中分离鉴定了4个新的单萜配糖体,命名为粗壮女贞甙D、G、H和L.通过滤谱及化学方法,它们分别鉴定为香叶醇3‘-O-μ-L-南鼠李糖基-4’-顺式香豆酰基-β-D-吡喃葡萄糖甙(1),6-羟基-3,7-二甲基-2E,7葵二烯醇3‘-O-α-L-吡喃鼠李糖基-4’反式香豆酰基-β-D-吡喃葡萄糖甙(2),6-羟基-3,7-二甲基-2E,7-葵二烯醇  相似文献   

2.
从贵州产雷公藤(TripterygiumwilfordiHokF.)中分离得到8个化合物,其中一个为新的降倍半萜化合物雷公藤酮(1),根据光谱(IR,1HNMR,13CNMR,HRMS,CD等)数据分析并通过X射线晶体分析确定了结构;另外7个化合物分别鉴定为雷公藤素(2),(±)6氧2(4′羟基3′,5′二甲氧苯基)3,7二氧杂二环[3.3.0]辛烷(3),tripterifordin(4),雷公藤内酯酮(5),雷公藤内酯醇(6),雷公藤内酯甲(7)和对乙氧基乙酰替苯胺(8).其中,3和8均为首次从该植物中分离得到.用二维核磁共振谱对3的氢谱和碳谱进行了指定  相似文献   

3.
川滇蔷薇和多苞蔷薇化学成分的研究   总被引:7,自引:0,他引:7  
从川滇蔷薇和多苞蔷薇中共分得10个单体,经光谱方法和与标准化合物比较,鉴定出7个化合物为:euscaphic acid(1),槲皮素(2),齐墩果酸(3),胡罗卜苷(4),β-谷甾醇(5),3-O-β-D-葡萄糖-(6-O-对羟基反式香豆酰基)-山奈素苷(6)和山奈素(7)。  相似文献   

4.
芒苞草的化学成分   总被引:4,自引:0,他引:4  
从芒包草(Acanthochlamys bracteata P. C. Kao)全草的甲醇撮物中分离出6个晶体,经波谱分析和与标准品对照,将它们分别鉴定为:豆甾醇(Ⅰ)、豆甾醇葡萄糖甙(Ⅱ)、7α-羟基豆甾醇(Ⅲa)和7β-羟基豆甾醇(Ⅲb)的混晶、棕榈酸(Ⅳ)、euscaphic acid(Ⅴ)、和槲皮素-3’,4’7-三甲醚(Ⅵ)。实验表明甾醇类化合物是该植物的主要次主代谢产物。这是该单种属科  相似文献   

5.
报道了从一株有较高半纤维素酶活性的Bacilussp.BT7克隆内切木聚糖酶基因的结果.以大肠杆菌XL1blue为宿主菌,采用水解圈检测法,在含有RBB木聚糖(4氧甲基D葡萄糖苷D木聚糖Remazol亮蓝R)的平板上分离到能水解RBB木聚糖的阳性克隆3个,对它们进行的限制酶作图和Southern杂交分析表明,它们属于3种不同的内切木聚糖酶基因  相似文献   

6.
从岩豆(Millettia dielsiana Harms ex Diels)种妇中分离纯化得到的岩豆凝集素(简称MDL)经链霉蛋白酶水解,测得其分子中含有4个色氨酸(Trp)残基。用N-溴代丁二酰亚胺(NBS)对MDL分子中的色氨酸残基进行化学修饰,在无变性剂存在下有3.6个Trp残基被修饰,在变性条件下可修饰3.8个Trp残基。修饰后MDL活性均丧失,且甘露糖对MDL活性雎有保护作用。表明Tr  相似文献   

7.
腺叶香茶菜的化学成分研究   总被引:1,自引:0,他引:1  
从腺叶香茶菜[Rabdosiaadenoloma(Hand.-Mazz.)Hara]地上部分的乙醇提取物中共分离出10个化合物.经EIMS、1HNMR和13CNMR等波谱和化学方法分别鉴定为:effusaninA(1)、effusaninE(2)、洋芹素-4',7-二甲醚(3)、β-谷甾醇(4)、柳杉二醇(5)、Uvaol(6)、白桦酸(7)、齐墩果酸(8),乌苏酸(9),齐墩果酸-3-O-α-L-鼠李吡喃糖基(1→2)[β-D-葡萄吡喃糖基-(1→4)]-α-L-阿拉伯吡喃糖甙(10).其中8的含量高达1%以上.上述化学成分均为首次从该植物中分离得到.  相似文献   

8.
攀枝花苏铁的化学成分   总被引:5,自引:0,他引:5  
首次从攀枝花苏铁(Cycaspanzhihuaensis)的茎、雄花、雌花和种子中共分离出7个化合物.经波谱分析和化学方法分别鉴定为:佳味酚β芸香糖苷(1),穗花杉双黄酮(2),罗汗松双黄酮甲(3),5,5″,7,7″,4′,4-六羟基(2′,8″)双黄酮(4),β谷甾醇(5),胡萝卜苷(6)和棕榈酸(7).其中1和4均为首次从苏铁植物中分离得到  相似文献   

9.
微生物降解蔬菜残留农药研究   总被引:36,自引:2,他引:34  
从富集培养物中筛选到以甲胺磷为唯一碳源生长的菌株NMJ5和以乐果为唯一碳源生长的菌株NML3,经鉴定分别为芽孢杆菌属(Bacilussp.)和假单胞菌属(Pseudomonassp.).它们利用甲胺磷、乐果生长的最适条件及在无机盐培养基中农药最大耐受浓度分别为pH7.5,t=35℃,ρ=1000mg/L和pH7.5,t=30℃,ρ=2000mg/L.在无碳基础培养基内单菌株培养8d,524mg/L的甲胺磷好气降解42.5%,厌气降解35.9%,250mg/L的乐果好气降解50.2%,厌气降解16.4%.小区试验表明,NMJ5、NML3的菌液制剂对普通白菜的变种南农矮脚黄(Brasicacampestrissp.chinensisL.var.communisTsenetLee)中残留的甲胺磷、乐果有明显的去除作用.  相似文献   

10.
硅营养缓解水稻幼苗Cd、Cr毒害的生理研究   总被引:58,自引:0,他引:58  
两系法杂交稻“培杂山青”和常规稻“双桂36”幼苗经较高浓度的Cd2+(c=9.6~38.4μmol/L)或Cr3+(c=7.5~25.0μmol/L)处理可使其叶片光合速率、叶绿素(a+b)含量、叶绿素a/b比值、叶片可溶性糖、淀粉及可溶性蛋白质含量降低,而叶片的POD活性提高;低浓度Cd2+(c=4.8μmol/L)和Cr3+(c=2.5μmol/L)处理幼苗对上述生理指标有提高作用,但POD活性稍降低.加Si(Na2SiO3)[c(SiO2)=1.331mmol/L]的Cd、Cr处理比不加Si的Cd、Cr处理的幼苗叶片上述生理指标明显提高,且明显降低其POD活性.说明Si在不同程度上起到缓解Cd、Cr对水稻幼苗的毒害作用.而c(Cr3+)=25.0μmol/L是“双桂36”幼苗的致死浓度  相似文献   

11.
Conservation science is a crisis discipline in which the results of scientific enquiry must be made available quickly to those implementing management. We assessed the extent to which scientific research published since the year 2000 in 20 conservation science journals is publicly available. Of the 19,207 papers published, 1,667 (8.68%) are freely downloadable from an official repository. Moreover, only 938 papers (4.88%) meet the standard definition of open access in which material can be freely reused providing attribution to the authors is given. This compares poorly with a comparable set of 20 evolutionary biology journals, where 31.93% of papers are freely downloadable and 7.49% are open access. Seventeen of the 20 conservation journals offer an open access option, but fewer than 5% of the papers are available through open access. The cost of accessing the full body of conservation science runs into tens of thousands of dollars per year for institutional subscribers, and many conservation practitioners cannot access pay‐per‐view science through their workplace. However, important initiatives such as Research4Life are making science available to organizations in developing countries. We urge authors of conservation science to pay for open access on a per‐article basis or to choose publication in open access journals, taking care to ensure the license allows reuse for any purpose providing attribution is given. Currently, it would cost $51 million to make all conservation science published since 2000 freely available by paying the open access fees currently levied to authors. Publishers of conservation journals might consider more cost effective models for open access and conservation‐oriented organizations running journals could consider a broader range of options for open access to nonmembers such as sponsorship of open access via membership fees. Obtención de Acceso Abierto a la Ciencia de la Conservación  相似文献   

12.
Summary Interactions were studied among alkaloid-containing legumes (Erythrina corallodendrum andSpartium junceum) and non-toxic plants (Citrus sinensis, Cucurbita moschata andEuphorbia tirucalli), several polyphagous homopterans,Aphis craccivora (Aphididae),Icerya purchasi, I. aegyptiaca (Margarodidae),Lepidosaphes ulmi (Diaspididae) andPlanococcus citri (Pseudococcidae), and some major natural enemies of these homopterans. Significant reductions in survival due to negative effects of alkaloid containing as compared with non-alkaloidal plants were recorded for the predatorsRodolia cardinalis andChilocorus bipustulatus, but not forCryptolaemus montrouzieri (Coleoptera: Coccinellidae),Chrysoperla carnea (Neuroptera: Chrysopidae) andSympherobius sanctus (Neuroptera: Sympherobiidae). The development time of the larvae or pupae ofR. cardinalis, C. carnea andS. sanctus was longer on the toxic plants than on the non-toxic ones. The percentage of parasitism ofA. craccivora collected from the non-alkaloidal plantsVicia palaestina andMelilotus albus was much higher than that onS. junceum. The parasitoid complexes ofA. craccivora differed between both plant groups. The nutritive value of honeydew ofI. purchasi andA. craccivora, as expressed by the life span ofEncyrtus infelix (Hymenoptera: Encyrtidae) adults, was also investigated. Life spans were significantly longer when the wasps fed on honeydew produced on non-alkaloidal plants (C. sinensis andPittosporum tobira) than on alkaloid containing plants whenI. purchasi — but notA. craccivora — was the producer. It is suggested that the chemical defense ofE. corallodendrum andS. junceum is exploited by polyphagous phytophages to reduce predation. In nature, population growth and density of four of the investigated homopterans are conspicuously high when they developed on the alkaloid containing plant species, and very low on non-alkaloid plants. The efficiency of their natural enemies may be reduced by sequestration of alkaloids (or other toxic plant compounds) or their transfer into excreted honeydew. Therefore it is assumed that a generalist phytophagous homopteran may be protected from its natural enemies, although at different rates of efficiency, if it can safely sequester the host allelochemical when it develops on toxic species within its host range.  相似文献   

13.
A bioblitz inexpensively and quickly generates biodiversity data, but bioblitzes are often conducted with haphazard, unreplicated sampling. Results tend to be taxonomically, geographically, or temporally biased, lack metadata, and consist of lists of observed taxa that do not enable further analyses or correction for imperfect detection. A rapid, recurring, structured survey (RRSS) uses a structured sampling design and temporal and spatial replication to survey randomly selected sites on a conservation property. We participated in a loosely structured bioblitz and a subsequent RRSS at Big Canoe Creek Nature Preserve in Springville (St. Clair County), Alabama (USA) to compare observed richness derived from the 2 survey approaches. The RRSS data structure enabled us to fit models that accounted for imperfect detection to estimate abundances, occupancy probabilities, and habitat associations. The loosely structured bioblitz data could not be used in such models. We present a new integrated multispecies abundance model that we applied to avian RRSS data. Our model extension enables estimation for the community, employs data augmentation to estimate the number of undetected species, and incorporates covariates. The RRSS generated a more comprehensive and less biased list of observed taxonomic richness than the loosely structured bioblitz (e.g., 73 vs. 45 bird species and 104 vs. 63 insect families from the RRSS vs. loosely structured bioblitz, respectively). Models fit to the RRSS data identified seasonal patterns in avian community composition and allowed for estimation of habitat–occupancy relationships for insect taxa. The RRSS protocol has potential for broad transferability as a standardized, quick, and inexpensive way to inventory biodiversity and estimate ecological parameters while providing an outreach opportunity.  相似文献   

14.
Summary Two South American polyphagous leaf beetles,Diabrotica speciosa andCerotoma arcuata, selectively accumulated the bitter tasting compound 23,24-dihydrocucurbitacin D in their body after ingesting root tissues of cucurbit plants. Similarly, three Asian Cucurbitaceae-feeding specialists in the genusAulacophora were found to sequester the same compound. Cucurbitacin analogs were shown to deter feeding by a bird predator, indicating an allomonal role for these compounds in cucurbitacin-associated chrysomelid leaf beetles both of New and Old Worlds. The strong affinity to cucurbitacins, selective sequestration of the analogs and consequent protection from predators suggested an ecological adaptation mechanism developed in common among these two geographically isolated subtribes in the Luperini.  相似文献   

15.
Abstract: In East Africa fire and grazing by wild and domestic ungulates maintain savannas, and pastoralists historically set fires and herded livestock through the use of temporary corrals called bomas. In recent decades traditional pastoral practices have declined, and this may be affecting biodiversity. We investigated the effects of prescribed fires and bomas on savanna bird communities in East Africa during the first and second dry seasons of the year (respectively before and after the rains that mark the onset of breeding for most birds). We compared abundance, richness, and community composition on 9‐ha burned plots, recently abandoned bomas, and control plots in the undisturbed matrix habitat over a 3‐year period. Generally, recently burned areas and abandoned bomas attracted greater densities of birds and had different community assemblages than the surrounding matrix. The effects of disturbances were influenced by interactions between primary productivity, represented by the normalized difference vegetation index, and time. Bird densities were highest and a greater proportion of species was observed on burned plots in the months following the fires. Drought conditions equalized bird densities across treatments within 1 year, and individuals from a greater proportion of species were more commonly observed on abandoned bomas. Yearly fluctuations in abundance were less pronounced on bomas than on burns, which indicate that although fire may benefit birds in the short term, bomas may have a more‐lasting positive effect and provide resources during droughts. Several Palearctic migrants were attracted to burned plots regardless of rainfall, which indicates continued fire suppression may threaten their already‐declining populations. Most notably, the paucity of birds observed on the controls suggests that the current structure of the matrix developed as a result of fire suppression. Traditional pastoralism appears critical to the maintenance of avian diversity in these savannas.  相似文献   

16.
Land-use change via human development is a major driver of biodiversity loss. To reduce these impacts, billions of dollars are spent on biodiversity offsets. However, studies evaluating offset project effectiveness that examine components such as the overall compliance and function of projects remain rare. We reviewed 577 offsetting projects in freshwater ecosystems that included the metrics project size, type of aquatic system (e.g., wetland and creek), offsetting measure (e.g., enhancement, restoration, and creation), and an assessment of the projects’ compliance and functional success. Project information was obtained from scientific and government databases and gray literature. Despite considerable investment in offsetting projects, crucial problems persisted. Although compliance and function were related to each other, a high level of compliance did not guarantee a high degree of function. However, large projects relative to area had better function than small projects. Function improved when projects targeted productivity or specific ecosystem features and when multiple complementary management targets were in place. Restorative measures were more likely to achieve targets than creating entirely new ecosystems. Altogether the relationships we found highlight specific ecological processes that may help improve offsetting outcomes.  相似文献   

17.
An argument is presented in which areas of natural arsenic contamination of modern groundwaters throughout Asia have a common origin. Arsenic originally accumulated in oceanic ferro-manganoan sediments of the eastern Palaeo-Tethys. This was further concentrated through oceanic crustal extinction in what later became the south-east Chinese accreted mineralised terrain. Proto-Himalayan uplift of this area created the palaeo-drainage systems of the Ganges – Brahmaputra, Irrawaddy, Mekong, and Red Rivers, with consequent headwater erosion of arsenic-rich sediments. Their downstream deposition as immature and easily redistributed Neogene sandstones, silts, and iron-rich clays has created secondary and tertiary reservoirs of adsorbed and authigenic arsenic, from which the current arsenic-rich groundwaters have evolved. Considering river basins within the above palaeo-hydrogeological framework provides a basis for assessing the risk of arsenic in groundwater basins of south and south-eastern Asia.  相似文献   

18.
Abstract: The last century has seen the ascendance of a core economic model, which we will refer to as Walrasian economics. This model is driven by the psychological assumptions that humans act only in a self‐referential and narrowly rational way and that production can be described as a self‐contained circular flow between firms and households. These assumptions have critical implications for the way economics is used to inform conservation biology. Yet the Walrasian model is inconsistent with a large body of empirical evidence about actual human behavior, and it violates a number of basic physical laws. Research in behavioral science and neuroscience shows that humans are uniquely social animals and not self‐centered rational economic beings. Economic production is subject to physical laws including the laws of thermodynamics and mass balance. In addition, some contemporary economic theory, spurred by exciting new research in human behavior and a wealth of data about the negative global impact of the human economy on natural systems, is moving toward a world view that places consumption and production squarely in its behavioral and biophysical context. We argue that abandoning the straightjacket of the Walrasian core is essential to further progress in understanding the complex, coupled interactions between the human economy and the natural world. We call for a new framework for economic theory and policy that is consistent with observed human behavior, recognizes the complex and frequently irreversible interaction between human and natural systems, and directly confronts the cumulative negative effects of the human economy on the Earth's life support systems. Biophysical economics and ecological economics are two emerging economic frameworks in this movement.  相似文献   

19.
Effects of Coffee Management on Deforestation Rates and Forest Integrity   总被引:1,自引:0,他引:1  
Knowledge about how forest margins are utilized can be crucial for a general understanding of changes in forest cover, forest structure, and biodiversity across landscapes. We studied forest‐agriculture transitions in southwestern Ethiopia and hypothesized that the presence of coffee (Coffea arabica)decreases deforestation rates because of coffee's importance to local economies and its widespread occurrence in forests and forest margins. Using satellite images and elevation data, we compared changes in forest cover over 37 years (1973–2010) across elevations in 2 forest‐agriculture mosaic landscapes (1100 km2 around Bonga and 3000 km2 in Goma‐Gera). In the field in the Bonga area, we determined coffee cover and forest structure in 40 forest margins that differed in time since deforestation. Both the absolute and relative deforestation rates were lower at coffee‐growing elevations compared with at higher elevations (?10/20% vs. ?40/50% comparing relative rates at 1800 m asl and 2300–2500 m asl, respectively). Within the coffee‐growing elevation, the proportion of sites with high coffee cover (>20%) was significantly higher in stable margins (42% of sites that had been in the same location for the entire period) than in recently changed margins (0% of sites where expansion of annual crops had changed the margin). Disturbance level and forest structure did not differ between sites with 30% or 3% coffee. However, a growing body of literature on gradients of coffee management in Ethiopia reports coffee's negative effects on abundances of forest‐specialist species. Even if the presence of coffee slows down the conversion of forest to annual‐crop agriculture, there is a risk that an intensification of coffee management will still threaten forest biodiversity, including the genetic diversity of wild coffee. Conservation policy for Ethiopian forests thus needs to develop strategies that acknowledge that forests without coffee production may have higher deforestation risks than forests with coffee production and that forests with coffee production often have lower biodiversity value. Efectos de la Administración Cafetalera sobre las Tasas de Deforestación y la Integridad de los Bosques  相似文献   

20.
Large, intact areas of tropical peatland are highly threatened at a global scale by the expansion of commercial agriculture and other forms of economic development. Conserving peatlands on a landscape scale, with their hydrology intact, is of international conservation importance to preserve their distinctive biodiversity and ecosystem services and maintain their resilience to future environmental change. We explored threats to and opportunities for conserving remaining intact tropical peatlands; thus, we excluded peatlands of Indonesia and Malaysia, where extensive deforestation, drainage, and conversion to plantations means conservation in this region can protect only small fragments of the original ecosystem. We focused on a case study, the Pastaza‐Marañón Foreland Basin (PMFB) in Peru, which is among the largest known intact tropical peatland landscapes in the world and is representative of peatland vulnerability. Maintenance of the hydrological conditions critical for carbon storage and ecosystem function of peatlands is, in the PMFB, primarily threatened by expansion of commercial agriculture linked to new transport infrastructure that is facilitating access to remote areas. There remain opportunities in the PMFB and elsewhere to develop alternative, more sustainable land‐use practices. Although some of the peatlands in the PMFB fall within existing legally protected areas, this protection does not include the most carbon‐dense (domed pole forest) areas. New carbon‐based conservation instruments (e.g., REDD+, Green Climate Fund), developing markets for sustainable peatland products, transferring land title to local communities, and expanding protected areas offer pathways to increased protection for intact tropical peatlands in Amazonia and elsewhere, such as those in New Guinea and Central Africa which remain, for the moment, broadly beyond the frontier of commercial development.  相似文献   

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