全文获取类型
收费全文 | 1189篇 |
免费 | 9篇 |
国内免费 | 28篇 |
专业分类
安全科学 | 41篇 |
废物处理 | 80篇 |
环保管理 | 111篇 |
综合类 | 209篇 |
基础理论 | 248篇 |
环境理论 | 2篇 |
污染及防治 | 397篇 |
评价与监测 | 75篇 |
社会与环境 | 61篇 |
灾害及防治 | 2篇 |
出版年
2023年 | 5篇 |
2022年 | 17篇 |
2021年 | 20篇 |
2020年 | 10篇 |
2019年 | 11篇 |
2018年 | 39篇 |
2017年 | 44篇 |
2016年 | 54篇 |
2015年 | 34篇 |
2014年 | 40篇 |
2013年 | 111篇 |
2012年 | 64篇 |
2011年 | 95篇 |
2010年 | 68篇 |
2009年 | 72篇 |
2008年 | 80篇 |
2007年 | 72篇 |
2006年 | 66篇 |
2005年 | 40篇 |
2004年 | 36篇 |
2003年 | 37篇 |
2002年 | 23篇 |
2001年 | 16篇 |
2000年 | 11篇 |
1999年 | 11篇 |
1998年 | 9篇 |
1997年 | 11篇 |
1996年 | 5篇 |
1995年 | 12篇 |
1994年 | 3篇 |
1993年 | 6篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1981年 | 3篇 |
1976年 | 2篇 |
1970年 | 2篇 |
1966年 | 3篇 |
1965年 | 7篇 |
1964年 | 5篇 |
1963年 | 5篇 |
1962年 | 10篇 |
1961年 | 11篇 |
1960年 | 2篇 |
1959年 | 2篇 |
1958年 | 2篇 |
1957年 | 2篇 |
1956年 | 3篇 |
1954年 | 3篇 |
1942年 | 2篇 |
1941年 | 2篇 |
排序方式: 共有1226条查询结果,搜索用时 25 毫秒
691.
Partitioning the factors of spatial variation in regeneration density of shade-tolerant tree species
Understanding coexistence of highly shade-tolerant tree species is a longstanding challenge for forest ecologists. A conceptual model for the coexistence of sugar maple (Acer saccharum) and American beech (Fagus grandibfolia) has been proposed, based on a low-light survival/high-light growth trade-off, which interacts with soil fertility and small-scale spatiotemporal variation in the environment. In this study, we first tested whether the spatial distribution of seedlings and saplings can be predicted by the spatiotemporal variability of light availability and soil fertility, and second, the manner in which the process of environmental filtering changes with regeneration size. We evaluate the support for this hypothesis relative to the one for a neutral model, i.e., for seed rain density predicted from the distribution of adult trees. To do so, we performed intensive sampling over 86 quadrats (5 x 5 m) in a 0.24-ha plot in a mature maple-beech community in Quebec, Canada. Maple and beech abundance, soil characteristics, light availability, and growth history (used as a proxy for spatiotemporal variation in light availability) were finely measured to model variation in sapling composition across different size classes. Results indicate that the variables selected to model species distribution do effectively change with size, but not as predicted by the conceptual model. Our results show that variability in the environment is not sufficient to differentiate these species' distributions in space. Although species differ in their spatial distribution in the small size classes, they tend to correlate at the larger size class in which recruitment occurs. Overall, the results are not supportive of a model of coexistence based on small-scale variations in the environment. We propose that, at the scale of a local stand, the lack of fit of the model could result from the high similarity of species in the range of environmental conditions encountered, and we suggest that coexistence would be stable only at larger spatial scales at which variability in the environment is greater. 相似文献
692.
Chang-Keun Kang Eun Jung Choy Yongsoo Son Jae-Young Lee Jong Kyu Kim Youngdae Kim Kun-Seop Lee 《Marine Biology》2008,153(6):1181-1198
Loss of macroalgae habitats has been widespread on rocky marine coastlines of the eastern Korean peninsula, and efforts for
restoration and creation of macroalgal beds have increasingly been made to mitigate these habitat losses. Deploying artificial
reefs of concrete pyramids with kelps attached has been commonly used and applied in this study. As a part of an effort to
evaluate structural and functional recovery of created and restored habitat, the macroalgal community and food web structure
were studied about a year after the establishment of the artificial macroalgal bed, making comparisons with nearby natural
counterparts and barren ground communities. Dominant species, total abundance, and community structure of macroalgal assemblage
at the restored macroalgal bed recovered to the neighboring natural bed levels during the study period. The main primary producers
(phytoplankton and macroalgae) were isotopically well separated. δ13C and δ15N values of consumers were very similar between restored and natural beds but varied greatly among functional feeding groups.
The range of consumer δ13C was as wide as that of primary producers, indicating the trophic importance of both producers. There was a stepwise trophic
enrichment in δ15N with increasing trophic level. A comparison of isotope signatures between primary producers and consumers showed that, while
suspension feeders are highly dependent on pelagic sources, invertebrates of other feeding guilds and fishes mainly use macroalgae-derived
organic matter as their ultimate nutritional sources in both macroalgal beds, emphasizing the high equivalency of trophic
structure between both beds. Isotopic signatures of a few mollusks and sea urchins showed that they use different dietary
items in macroalgal-barren grounds compared with macroalgal beds, probably reflecting their feeding plasticity according to
the low macroalgal biomass. However, isotopic signatures of most of the consumers at the barren ground were consistent with
those at the macroalgal beds, supporting the important trophic role of drifting algae. Our results revealed the recoveries
of the macroalgal community and trophic structure at the restored habitat. Further studies on colonization of early settlers
and the following succession progress are needed to better understand the process and recovery rate in the developing benthic
community. 相似文献
693.
Carin Jantzen Christian Wild Mohammed El-Zibdah Hilly Ann Roa-Quiaoit Christoph Haacke Claudio Richter 《Marine Biology》2008,155(2):211-221
Two species of giant clams, Tridacna maxima and T. squamosa, coexist in the Red Sea, but exhibit distinctly different depth distributions: T. maxima mostly occurs in shallow waters (reef flat and edge), while T. squamosa may occur down to the lower fore-reef slope. Giant clams have been described as mixotrophic, capable of both filter-feeding
and photosynthesis due to algal symbionts (zooxanthellae), therefore, observed depth preferences were investigated in relation
to possible differences in autotrophy vs. heterotrophy. This study was conducted from April to June 2004, at the reef near
the Marine Science Station, Aqaba, Gulf of Aqaba, Red Sea, and in May 2007, at a reef near Dahab, Sinai Peninsula, Egypt.
In situ measurements using a submersible pulse amplitude modulated fluorometer (Diving PAM), revealed no significant differences
in effective PSII quantum yield (ΔF/Fm′) and relative electron transport rates (ETR) between the two species; but rapid light curves (ETR vs. light, photosynthetically
active irradiance, PAR) showed significant differences in maximum photosynthetic rates (ETRmax), with 20% higher values in T. maxima. Chamber incubations displayed higher net and gross oxygen production by T. maxima (88.0 and 120.3 μmol O2 cm−2 mantle area day−1) than T. squamosa (56.7 and 84.8 μmol O2 cm−2 mantle area day−1); even under shading conditions (simulated depth of 20 m) T. maxima still achieved 93% of the surface gross O2 production, whereas T. squamosa reached only 44%. A correlation was found between ETR and net photosynthesis measured as oxygen production (T. maxima: R
2 = 0.53; T. squamosa: R
2 = 0.61). Calculated compensation depth (CD) (gross photosynthesis equals respiration) in T. maxima (16 m) matches the maximum depth of occurrence in this study (17 m). By contrast, the CD of T. squamosa (9 m) was much shallower than the maximum vertical range (42 m). Findings suggest T. maxima is a strict functional photoautotroph limited by light, whereas T. squamosa is a mixotroph whose photoautotrophic range is extended by heterotrophy.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
694.
Yuan LI Yanqun ZU Qixian FANG Zhaohua GAO Christian SCHVARTZ 《Frontiers of Environmental Science & Engineering》2009,3(3):325-333
This paper studied the relationship between heavy metal concentrations of herbaceous plants and soils at four Pb-Zn mining sites in Yunnan, China. 50 herbaceous plant samples of 9 plant species from 4 families and 50 soil samples were collected and then ana1yzed for the tota1 concentrations of Pb, Cd, and Zn. The results showed that the average concentrations of Pb, Cd, and Zn in soil samples were 3772.83, 168.81, and 5385.65 mg/kg, respectively. The average concentrations of Pb, Cd, and Zn were 395.68, 28.14, and 1664.20 mg/kg in the shoots, and 924.12, 57.25, and 1778.75 mg/kg in the roots, respectively. Heterospecific plants at the same site and conspecific plants at various sites had different average levels of Pb, Cd, and Zn, both in the shoots and the roots. Enrichment coefficients of Pb, Cd, and Zn were greater than 1 in 2, 3, and 9 herbaceous plant samples, respectively. Translocation factors of Pb, Cd, and Zn were greater than 1 in 10, 17, and 25 herbaceous plant samples, respectively. In all 50 samples, the concentrations of Pb, Cd, and Zn between the shoots and the roots, the shoots, and the soils, and the roots and the soils had significant positive relationships. 相似文献
695.
在液相/离子阱质谱上,利用液相/质谱/质谱方法对鸡肉及虾仁中硝基呋喃代谢物残留进行了定性定量分析.对于四种硝基呋喃代谢物,其定量限在0125到05μg·kg-1的范围内,分析结果完全满足欧盟的1μg·kg-1的最低检测限量的要求. 相似文献
696.
Survey of coastal inland pollution sources and their influence on seawater quality in Doam bay,Korea
Jinsoo Suh Seyeon Shin Hyung-Yeel Kahng Samyoung Ahn Young-Sun Lee Jae-Sung Jung 《Environmental monitoring and assessment》2018,190(10):605
Inland pollution sources of Doam bay were investigated from August to October in 2013. A total of 210 sources including rivers, streams, domestic, agricultural and industrial discharge points were identified along the coast, including 32 sources that had outflow. Agricultural sources were the largest inland pollution sources (139, 66.2%). Fecal coliform concentrations were measured. These data were combined with water discharge data to determine daily loads of pollutants discharged from each source into the bay. Fecal coliform concentrations were the highest in domestic discharges. However, they only had slight influence because their discharge volume was small. The most significant pollution source was Tamjin River (St.85) due to large amount of discharge volume. The influence of St.85 reached almost half of Doam bay. Fecal coliform levels of streams increased after rainfall, but decreased overtime. Domestic pollution sources were not affected upon rain event. 相似文献
697.
Archetypical patterns and trajectories of land systems in Europe 总被引:1,自引:0,他引:1
Levers Christian Müller Daniel Erb Karlheinz Haberl Helmut Jepsen Martin Rudbeck Metzger Marc J. Meyfroidt Patrick Plieninger Tobias Plutzar Christoph Stürck Julia Verburg Peter H. Verkerk Pieter J. Kuemmerle Tobias 《Regional Environmental Change》2018,18(3):715-732
Regional Environmental Change - Assessments of land-system change have dominantly focused on conversions among broad land-use categories, whereas intensity changes within these categories have... 相似文献
698.
Henne Paul D. Bigalke Moritz Büntgen Ulf Colombaroli Daniele Conedera Marco Feller Urs Frank David Fuhrer Jürg Grosjean Martin Heiri Oliver Luterbacher Jürg Mestrot Adrien Rigling Andreas Rössler Ole Rohr Christian Rutishauser This Schwikowski Margit Stampfli Andreas Szidat Sönke Theurillat Jean-Paul Weingartner Rolf Wilcke Wolfgang Tinner Willy 《Regional Environmental Change》2018,18(1):205-221
Regional Environmental Change - Planning for the future requires a detailed understanding of how climate change affects a wide range of systems at spatial scales that are relevant to humans.... 相似文献
699.
Christian Bjerregaard-Olesen Manhai Long Mandana Ghisari Bodil H Bech Ellen A Nohr Niels Uldbjerg Tine B Henriksen Jørn Olsen Eva C Bonefeld-Jørgensen 《Environmental science and pollution research international》2017,24(20):16592-16603
The use of the lipophilic persistent organic pollutants (POPs) including polychlorinated biphenyls (PCBs) and several organochlorine pesticides (OCPs) has been prohibited for more than 30 years. In this study, we present the temporal trends of the lipophilic POP serum concentrations in Danish nulliparous pregnant women between 2011 and 2013. We randomly selected 197 pregnant women (gestational age 11–13) from the Aarhus Birth Cohort. The concentrations of the lipophilic POPs in the serum samples were analyzed using gas chromatography. The concentrations were corrected for total serum lipids. The statistical analysis was performed by regression analysis with adjustment for age, BMI, gestational age at blood draw, and smoking status. The serum concentrations of PCB 118, 138, 153, 156, 170, 180, 187, and hexachlorobenzen, trans-nonachlor, β-hexachlorocyclohexane (β-HCH), and p,p’-dichlorodiphenyldichloroethylene were lower in 2013 than in 2011. However, the oxychlordane concentration was lowest in 2011. The serum levels of most lipophilic POPs followed downward trends during the study period, which was expected, as these compounds has been banned for many years. The upward trend of oxychlordane was unexpected and presumably a chance finding. 相似文献
700.
Jan E. Vermaat Fritz A. Hellmann Astrid J. A. van Teeffelen Jelle van Minnen Rob Alkemade Regula Billeter Carl Beierkuhnlein Luigi Boitani Mar Cabeza Christian K. Feld Brian Huntley James Paterson Michiel F. WallisDeVries 《Ambio》2017,46(3):277-290
Current observed as well as projected changes in biodiversity are the result of multiple interacting factors, with land use and climate change often marked as most important drivers. We aimed to disentangle the separate impacts of these two for sets of vascular plant, bird, butterfly and dragonfly species listed as characteristic for European dry grasslands and wetlands, two habitats of high and threatened biodiversity. We combined articulations of the four frequently used SRES climate scenarios and associated land use change projections for 2030, and assessed their impact on population trends in species (i.e. whether they would probably be declining, stable or increasing). We used the BIOSCORE database tool, which allows assessment of the effects of a range of environmental pressures including climate change as well as land use change. We updated the species lists included in this tool for our two habitat types. We projected species change for two spatial scales: the EU27 covering most of Europe, and the more restricted biogeographic region of ‘Continental Europe’. Other environmental pressures modelled for the four scenarios than land use and climate change generally did not explain a significant part of the variance in species richness change. Changes in characteristic bird and dragonfly species were least pronounced. Land use change was the most important driver for vascular plants in both habitats and spatial scales, leading to a decline in 50–100% of the species included, whereas climate change was more important for wetland dragonflies and birds (40–50 %). Patterns of species decline were similar in continental Europe and the EU27 for wetlands but differed for dry grasslands, where a substantially lower proportion of butterflies and birds declined in continental Europe, and 50 % of bird species increased, probably linked to a projected increase in semi-natural vegetation. In line with the literature using climate envelope models, we found little divergence among the four scenarios. Our findings suggest targeted policies depending on habitat and species group. These are, for dry grasslands, to reduce land use change or its effects and to enhance connectivity, and for wetlands to mitigate climate change effects. 相似文献