首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   143篇
  免费   0篇
  国内免费   1篇
安全科学   4篇
废物处理   3篇
环保管理   10篇
综合类   43篇
基础理论   39篇
污染及防治   37篇
评价与监测   6篇
社会与环境   2篇
  2022年   1篇
  2021年   3篇
  2020年   3篇
  2019年   5篇
  2018年   5篇
  2017年   2篇
  2016年   4篇
  2015年   4篇
  2014年   7篇
  2013年   10篇
  2012年   3篇
  2011年   7篇
  2010年   13篇
  2009年   5篇
  2008年   4篇
  2007年   13篇
  2006年   3篇
  2005年   4篇
  2004年   2篇
  2003年   3篇
  2002年   2篇
  2001年   5篇
  2000年   1篇
  1999年   1篇
  1998年   1篇
  1997年   3篇
  1996年   1篇
  1995年   5篇
  1992年   1篇
  1991年   2篇
  1985年   1篇
  1963年   2篇
  1962年   1篇
  1958年   1篇
  1956年   3篇
  1955年   2篇
  1950年   1篇
  1942年   1篇
  1941年   1篇
  1938年   1篇
  1937年   1篇
  1934年   3篇
  1933年   1篇
  1928年   1篇
  1926年   1篇
排序方式: 共有144条查询结果,搜索用时 21 毫秒
51.
Oxygen and carbon stable isotope profiles were constructed for two species of large subtropical gastropods of the family Fasciolariidae—Triplofusus giganteus and Fasciolaria tulipa—from the Florida Keys and the Bahamas, to evaluate their life history and to assess their potential as paleoenvironmental proxies. Oxygen isotope profiles revealed T. giganteus and F. tulipa grew their shells for 6 and 3 years, respectively. Both mollusks show faster growth rates during the first half of their lifespan. Mean annual temperatures (MAT) derived from oxygen isotopes for T. giganteus were 26.5 °C and for F. tulipa were 26.7 °C, both matching instrumental MATs of 26.7 and 26.5 °C for the Florida Keys. Both shells, however, failed to record entire mean annual temperature ranges (MART). Fasciolaria tulipa yielded a calculated MART of 5.6 °C compared with a measured MART of 9.3 °C, and T. giganteus showed a calculated MART of 6.9 °C compared with a measured MART of 9.4 °C. Carbon isotopes of T. giganteus were ambiguous and reveal no significant relationships with trends in nutrient concentrations (N and P), dissolved oxygen, and dissolved organic carbon, although they did exhibit more negative values concomitant with landfall of Hurricane Irene and trended to increasing values with ontogeny that could reflect migration. Carbon isotopes in F. tulipa were lower during winters, possibly reflecting seasonal upwelling or seagrass-mediated carbon cycling.  相似文献   
52.
Originally developed within the Mediterranean, a tested coastal management and planning tool was applied outside the region to evaluate its international scope, with particular reference to a less developed country. Seven coastal sites in Pakistan were investigated for their scenic values through a 26 item checklist grouped as physical and human parameters analysed though weighted parameters and fuzzy logic matrices. With respect to a five-class evaluation system, results indicated: Jiwani, Miani Hor and Pasni-Astola Island as extremely attractive natural sites with very high landscape value (classified as Class 1 sites); Mubarak village as an attractive natural site with high landscape value (classified as a Class 2 site); Kaka pir village, Harjana village and Keti Bandar as having little outstanding landscape features or with urban environment and classified as Class 3 sites. Rural and/or urban environmental influences were observed to be critical factors which influenced major human parameters that ultimately affect sites’ scenic classification. However, notwithstanding natural attraction, unless political and social development barriers are tackled in conjunction with recognising areas that possess inherent tourism potential, economic potential is unlikely to be realised.  相似文献   
53.
54.

Soils can be contaminated by pharmaceuticals. The aim of this study was to evaluate the impact of soil conditions (influencing sorption and persistence of pharmaceuticals in soils) and plant type on the root uptake of selected pharmaceuticals and their transformation in plant-soil systems. Four plants (lamb’s lettuce, spinach, arugula, radish) planted in 3 soils were irrigated for 20 days (26) with water contaminated by one of 3 pharmaceuticals (carbamazepine, atenolol, sulfamethoxazole) or their mixture. The concentrations of pharmaceuticals and their metabolites in soils and plant tissues were evaluated after the harvest. Sulfamethoxazole and atenolol dissipated rapidly from soils. The larger concentrations of both compounds and an atenolol metabolite were found in roots than in leaves. Sulfamethoxazole metabolites were below the limits of quantifications. Carbamazepine was stable in soils, easily uptaken, accumulated, and metabolized in plant leaves. The efficiency of radish and arugula (both family Brassicaceae) in metabolizing was very low contrary to the high and moderate efficiencies of lamb’s lettuce and spinach, respectively. Compounds’ transformations mostly masked the soil impact on their accumulation in plant tissues. The negative relationships were found between the carbamazepine sorption coefficients and its concentrations in roots of radish, lamb’s lettuce, and spinach.

  相似文献   
55.
The benthic macrofauna and physical features of 10 sandy beaches along the coast of Oman were surveyed quantitatively. This is a mesotidal regime mostly subject to low to moderate wave energy but more exposed in the south. Five northern beaches are tide-dominated, with low wave energy, and their profiles consist of a berm, a steep, swash-dominated upper shore and a broad tide-dominated terrace from mid-shore downwards. They are composed of moderately sorted fine to medium sands. Southern beaches experience greater wave energy, particularly during the summer southwest monsoon, and exhibit smoother, concave profiles with fine, fairly well sorted carbonate sand. 58 species and species groups were recorded, with crustanceans, polychaetes and molluscs dominant. In general species richness was high, at least 19–25 species per beach, but dry biomass moderate to low at 26–90g/m shoreline, with one high value of 450g/m. Total abundance was moderate at 3–73×103 organisms/m of beach. Some zonation was evident with ocypodid crabs andTylos in the supralittoral, cirolanid isopods on the upper shore and a variety of species on the lower shore. The coast of Oman appears to constitute a single zoogeographic region, but with some regional differentiation between north and south due to varying physical conditions. Thus, OmanÕs beaches are characterized by tide-dominated morphodynamics and exceptionally high species richness.  相似文献   
56.
Aircraft de-icing fluids (ADF) are a source of water and soil pollution in airport sites. Propylene glycol (PG) is a main component in several commercial formulations of ADFs. Even though PG is biodegradable in soil, seasonal overloads may result in occasional groundwater contamination. Feasibility studies for the biostimulation of PG degradation in soil have been carried out in soil slurries, soil microcosms and enrichment cultures with and without the addition of nutrients (N and P sources, oligoelements), alternative electron acceptors (nitrate, oxygen releasing compounds) and adsorbents (activated carbon). Soil samples have been taken from the contaminated area of Gardermoen Airport Oslo. Under aerobic conditions and in the absence of added nutrients, no or scarce biomass growth is observed and PG degradation occurs by maintenance metabolism at constant removal rate by the original population of PG degraders. With the addition of nutrient, biomass exponential growth enhances aerobic PG degradation also at low temperatures (4 ° C) that occur at the high season of snowmelt. Anaerobic PG degradation without added nutrients still proceeds at constant rate (i.e. no biomass growth) and gives rise to reduced fermentation product (propionic acid, reduced Fe and Mn, methane). The addition of nitrate does not promote biomass growth but allows full PG mineralization without reduced by-products. Further exploitation on the field is necessary to fully evaluate the effect of oxygen releasing compounds and adsorbents.  相似文献   
57.
Investigators have typically relied on a single or few discrete time points as measures of polychlorinated biphenyl (PCB) body burden, however health effects are more likely to be the result of integrative exposure in time, optionally expressed as an area under the time curve (AUC) of PCB serum concentration. Using data from a subgroup of 93 infants from a birth cohort in eastern Slovakia—a region highly polluted by PCBs—we fit a system type model, customized to our longitudinal measures of serum PCB concentrations in cord, 6, 16, and 45 month blood specimens. The most abundant congener, PCB 153, was chosen for modeling purposes. In addition to currently used methods of exposure assessment, our approach estimates a concentration time profile for each subject, taking into account mean residence time of PCB 153 molecules in the body, duration of breast feeding, hypothetical PCB 153 concentration in steady-state without breast feeding and alternately without normal food intake. Hypothetical PCB 153 concentration in steady-state without normal food intake correlates with AUC (r = 0.84, p < 0.001) as well as with duration of breast feeding (r = 0.64, p < 0.001). It makes possible to determine each subject’s exposure profile expressed as AUC of PCBs serum concentration with a minimum model parameters. PCB body burden in most infants was strongly associated with duration of breast feeding in most, but not all children, was apparent from model output.  相似文献   
58.
The US Army Corps of Engineers often requires wetland creation or restoration as compensation for wetlands damaged during development. These wetlands are typically monitored postconstruction to determine the level of compliance with respect to site-specific performance standards. However, defining appropriate goals and measuring success of restorations has proven difficult. We reviewed monitoring information for 76 wetlands constructed between 1992 and 2002 to summarize the performance criteria used to measure progress, assess compliance with those criteria, and, finally, to evaluate the appropriateness of those criteria. Goals were overwhelmingly focused on plant communities. Attributes used to assess the quality of restored plant communities, including percent native species and the Floristic Quality Index, increased over time but were apparently unrelated to the number of species planted. Compliance frequencies varied depending on site goals; sites often failed to comply with criteria related to survival of planted vegetation or requirements that dominant plant species should not be exotic or weedy, whereas criteria related to the establishment of cover by vegetation or by wetland-dependent plants were often met. Judgment of a site’s success or failure was largely a function of the goals set for the site. Some performance criteria were too lenient to be of value in distinguishing failed from successful sites, whereas other criteria were unachievable without more intensive site management. More appropriate goals could be devised for restored wetlands by basing performance standards on past performance of similar restorations, identifying consistent temporal trends in attributes of restored sites, and using natural wetlands as references.  相似文献   
59.
In polluted district of Michalovce in East Slovakia (POLL) and two districts with background pollution (BCGR) 2046 adults (834 males and 1212 females aged 20-75 years) were examined. Serum levels of thyrotropin (TSH), free thyroxine (FT4), total triiodothyronine (TT3) and antithyroperoxidase antibodies (TPOab) were estimated by electrochemiluminiscent assay and also these of 15 polychlorinated biphenyl congeners (PCBs), p,p'-DDE, p,p'-DDT, hexachlorobenzene (HCB) and hexachlorocyclohexane were measured by high resolution gas chromatography/mass spectrometry. In addition, also dioxins, furans, coplanar- and mono-ortho-PCBs as well as selected hydroxylated and methylsulphonated PCBs and DDE metabolites were measured by appropriate methods based on gas chromatography/mass spectrometry principle. In POLL significantly higher levels of all organochlorines were found than these in BCGR. When pooled values from both areas were stratified in terms of PCBs level and treated as continuous variables, positive association of PCBs with FT4 and TT3 was found, the latter two being also mutually associated. However, within the category of PCBs level <530 ng/glipid (n=232) the association between PCBs and both the FT4 (p<0.09) and TT3 (p<0.03) was negative and any association of these was not found within the category of PCBs level of 531-1000 ng/g (n=691). In contrast, in the category of 531-2000 ng/g (n=1307) positive association appeared between PCBs and FT4 (p<0.001) as well as TT3 (p<0.05). Highly significant association of PCBs with FT4 (p<0.001) was further found in the categories with PCBs level of 1001-101414 ng/g (n=1307) and 2001-101414 (n=1123), while significant association with TT3 was observed only in the category of 531-2000 ng/g. Such findings suggest possible threshold level in positive effect of PCBs on FT4 and TT3 level which seems to be individual and located somewhere around the PCBs level of 1000 ng/g. However, highly significant negative association of both FT4 and TT3 with TSH was found in each of above indicated PCBs categories. Considerable difference in FT4 and TT3 level between large groups of subjects with the same range of PCBs level was also found suggesting different individual susceptibility to the effects of organochlorines. Among a total of 26 cases from POLL with very low TSH level (<0.5 mU l(-1)) 13 cases showed very high level of PCBs, FT4 and TT3, thus supporting a hypothesis on a novel sporadic form of high PCBs related peripheral subclinical hyperthyroidism possibly resulting from the long-term disruption of equilibrium between bound and free thyroxine in plasma by high PCBs level followed by a striking inhibition of TSH release from the pituitary.  相似文献   
60.
Polychlorinated biphenyls (PCBs) were commercially produced between 1959 and 1984 in eastern Slovakia. Improper handling led to a highly contaminated local environment and high levels of PCBs in humans and wildlife in the Michalovce area. The aim of this study was to analyse serum for methylsulfonyl metabolites of PCB (MeSO(2)-PCBs) and DDE (3-MeSO(2)-DDE) in serum samples from pregnant women and in a selected number of paired cord blood samples to assess maternal sulfone levels and patterns, and transplacental transfer of these metabolites. The donating women were from two districts in eastern Slovakia. A liquid-liquid extraction method together with separation of substance groups and further clean-up on silica gel columns were applied prior to analysis by gas chromatography/mass spectrometry. 3-MeSO(2)-DDE was the major methyl sulfone in most of the samples followed by a yet not identified MeSO(2)-hexaCB, 4'-MeSO(2)-CB101, 4'-MeSO(2)-CB87 and 4-MeSO(2)-CB149. The women from the contaminated area had three times higher concentrations of the MeSO(2)-PCBs than women from the reference area. This is the first report on methyl sulfone metabolites of PCB and DDE in human cord serum. It is shown that these metabolites are transported through the placenta. The levels of MeSO(2)-PCBs in the maternal serum were about 1.5 times higher than in the corresponding cord serum on a lipid weight basis. For 3-MeSO(2)-DDE, the levels were about the same in maternal and cord serum. The difference in the maternal:cord ratio, comparing MeSO(2)-PCBs with 3-MeSO(2)-DDE might be due to differences in transport through the placenta caused by their different affinities for lipoproteins and plasma proteins.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号