全文获取类型
收费全文 | 50639篇 |
免费 | 586篇 |
国内免费 | 639篇 |
专业分类
安全科学 | 1726篇 |
废物处理 | 2358篇 |
环保管理 | 6656篇 |
综合类 | 8141篇 |
基础理论 | 13315篇 |
环境理论 | 25篇 |
污染及防治 | 12760篇 |
评价与监测 | 3451篇 |
社会与环境 | 3105篇 |
灾害及防治 | 327篇 |
出版年
2023年 | 226篇 |
2022年 | 480篇 |
2021年 | 530篇 |
2020年 | 360篇 |
2019年 | 443篇 |
2018年 | 772篇 |
2017年 | 796篇 |
2016年 | 1188篇 |
2015年 | 924篇 |
2014年 | 1403篇 |
2013年 | 4092篇 |
2012年 | 1727篇 |
2011年 | 2344篇 |
2010年 | 1907篇 |
2009年 | 1938篇 |
2008年 | 2330篇 |
2007年 | 2326篇 |
2006年 | 2067篇 |
2005年 | 1777篇 |
2004年 | 1678篇 |
2003年 | 1733篇 |
2002年 | 1569篇 |
2001年 | 1928篇 |
2000年 | 1369篇 |
1999年 | 832篇 |
1998年 | 608篇 |
1997年 | 618篇 |
1996年 | 632篇 |
1995年 | 749篇 |
1994年 | 706篇 |
1993年 | 593篇 |
1992年 | 633篇 |
1991年 | 619篇 |
1990年 | 608篇 |
1989年 | 570篇 |
1988年 | 504篇 |
1987年 | 449篇 |
1986年 | 414篇 |
1985年 | 425篇 |
1984年 | 467篇 |
1983年 | 441篇 |
1982年 | 463篇 |
1981年 | 386篇 |
1980年 | 310篇 |
1979年 | 340篇 |
1978年 | 299篇 |
1977年 | 228篇 |
1975年 | 245篇 |
1973年 | 232篇 |
1972年 | 243篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
951.
The contamination and distribution of organochlorinated compounds were considered in three crustacean species (edible crab, Cancer pagurus; spider crab, Maja brachydactyla; velvet swimming crab, Necora puber) from five sites along the coasts of Brittany and Normandy (Western and North-Western France). PCBs (16 single congeners), pp'-DDE and HCB were measured in hepatopancreas, gonads and muscle: in all, 175 samples were analysed. The spider crab was the only species found in the five sampling sites, thus enabling comparison between areas. Specimens from Antifer were much more contaminated (summation operator 16 PCBs in hepatopancreas=2000-4000 ng g(-1) dry weight) than those from other sites (50-1000 ng g(-1) d.w.). Among all the three species, the spider crab appeared more contaminated by PCBs than the edible crab, by a factor 2-3, probably in relation with specific differences in their life cycle. There was no difference due to the gender of the species. Within the different analysed tissues, contamination levels increased from muscle to gonads and hepatopancreas in relation with the fat content. A very similar PCB composition was observed in all samples, PCB fingerprints being characterised by the relative importance of the more persistent PCB congeners: CB153, 138, 180, 187, and 118. Finally, these results were compared to recent food regulations first of maximum marker PCB intake and secondly of maximum dioxin-like PCB intake. By considering the muscle, all samples were far below the regulatory limits; for hepatopancreas and gonads, however, some samples were unfit for human consumption. 相似文献
952.
The temporal variability and bioaccumulation dynamics of individual PCBs were studied in a detritivorous fish (Sábalo: Prochilodus lineatus) collected from 1999 to 2005 in the polluted Buenos Aires coastal area. Fish muscles contain high concentrations of total PCBs (11+/-7.2, 4.6+/-3.4 or 19+/-13 microg g(-1), dry, fresh and lipid weight, respectively) reflecting chronic bioaccumulation from sewage-industrial particulates. On a temporal basis, lipid normalized PCBs concentrations peaked by the end of 2001-2002 coincident with the rainiest period over the last four decades and shortly after PCB prohibition in the country, reflecting massive discharges to the coastal ecosystem. PCB composition in fish muscles show a prevailing contribution of hexachlorobiphenyls (35+/-4.2%), followed by hepta (23+/-3.0%), penta (20+/-3.6%), tri-tetra (16+/-4.8%) and minor proportions of octa-decachlorobiphenyls (5.7+/-3.1%) similar to an Aroclor 1242-1254-1260 1:2:4 mixture. During 2001-2002 maxima fish showed an enrichment in tri-tetrachlorobiphenyls ( approximately 1242-1254-1260 1:1:1 mixture) denoting a fresher signature. Fish/settling material lipid-organic carbon accumulation factors (BSAFs: 2.4-46, average: 21+/-10) plotted against kow showed a parabolic trend (BSAFs=-0.38 log kow2 + 5.16 log kow -15.85; R2=0.46) maximizing at hexa, hepta and octachlorobiphenyl 203 with reduced bioaccumulation of a few hepta (170, 191) and most octa-decachlorobihenyls suggesting limited intestinal absorption. 相似文献
953.
Hannam ML Hagger JA Jones MB Galloway TS 《Environmental pollution (Barking, Essex : 1987)》2008,152(2):342-350
Here, we identify and characterise cholinesterase (ChE) and carboxylesterase (CbE) activities in the body tissues of the sediment dwelling worm Arenicola marina. Exposure to the organophosphorus pesticide azamethiphos yielded an in vitro IC50 of 5 microg l(-1) for propionylcholinesterase (PChE). PChE was significantly inhibited in vivo after a 10 day exposure to 100 microg l(-1) azamethiphos, equivalent to the recommended aquatic application rate (ANOVA; F=2.75, P=0.033). To determine sensitivity to environmental conditions, A. marina were exposed for 10 days to field collected sediments. PChE activity was significantly lower in worms exposed to sediments from an estuary classified to be at high risk from point source pollution by the UK Environment Agency (ANOVA; F=15.33, P<0.001). Whilst causality cannot be directly attributed from these latter exposures, they provide an important illustration of the potential utility of esterase activity as a biomarker of environmental quality in this ecologically relevant sentinel species. 相似文献
954.
Peng Lian Andres F. Mejia Zhengdong Cheng M. Sam Mannan 《Journal of Loss Prevention in the Process Industries》2010,23(2):337-345
Accidental release of pressurized high flash point heat transfer fluids can result in fire and explosion hazard scenarios in the process industry. An experimental investigation on ignition of aerosols of a heat transfer fluid is carried out, and characterization of aerosol and its ignition process by non-intrusive laser diffraction technique is reported. Propagation speed of the aerosol combustion flame front as analyzed from the laser diffraction measurement agrees with high-speed visual camera observation. Flammability of the aerosol, which is based on the chances of the global flame appearance in the aerosol, is mainly controlled by aerosol droplet size and the droplet volume concentration. 相似文献
955.
Idiosyncratic deals in contemporary organizations: A qualitative and meta‐analytical review 下载免费PDF全文
Idiosyncratic deals (i‐deals) research focuses on the emergence of customized work arrangements employees negotiate with their employers. This article provides a critical review and synthesis of i‐deals research, combining a qualitative review of i‐deals theory and research with a supplementary meta‐analysis of 23 empirical studies (k = 27 samples, N = 8110 individuals). The qualitative review examines the conceptualization and measurement of i‐deals and identifies patterns and gaps in i‐deals research, while the quantitative meta‐analysis tests the moderating effect of societal cultures on the predictors and consequences of ideals investigated to date. In each section, attention is given to strengths and weaknesses of current approaches to i‐deals theory and research. Future research directions are identified with particular emphasis on the largely unexamined role of i‐deals from a multilevel perspective. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
956.
Affirmative Action Programs (AAPs) are becoming increasingly common in the workplace. Typically their effectiveness has been assessed by the number of women and minorities hired and promoted. A neglected, but important measure of effectiveness is how AAPs are perceived by employees. When employees perceive that AAPs violate notions of fairness, negative attitudes and behaviors may occur and lead to decreased organizational performance. A model of perceived AAP fairness is presented using an organizational justice perspective. An initial (partial) test of the model is conducted and avenues for future research are discussed. 相似文献
957.
958.
In studies of occupational risks, severity, which is a component of the estimation of every risk, appears as a multifaceted entity assessable according to numerous criteria. A method of measuring the degree of severity of the consequences of potentially dangerous events would be of undeniable value to organisations seeking to improve their understanding of the complexity of such events. The need to control severity is highlighted by scientifically acquired improvements in the understanding of occupational risks, by certain new regulatory obligations in Europe, and by some requirements in the financial management of organisations. We put forward a statistical way of integrating several constituent elements of severity and hence of determining a relevant, synthetic, one-dimensional index. This is achieved by means of principal component analysis (PCA), which is used here to calculate a resultant severity, as in some physical measurements. We also investigate how severity may be statistically modelled, with the aim of contributing to the quantitative assessment of occupational risks. The choice of parametric models is detailed and illustrated by the search for a suitable model for workplace accidents in an organisational setting. The practical value of modelling severity is two-fold. First, one is able to study the distribution of the numerical values of severity over a continuum (a theoretically infinite numerical set) rather than through a limited number of arbitrarily defined categories. Second, with a generally applicable parametric model, one can estimate the law of probability of a measurement of severity in a particular situation, notably recent or new. Lastly, the statistical concept of risk curve is defined and discussed. The goal is to incorporate the severity component into the risk assessment in the form of a probability law, thus circumventing the difficulties associated with an analysis of scenarios. 相似文献
959.
960.
Russian Journal of Ecology - Abstract—Long-term observations (1968–2019) on the dynamics of infection by the cestode Eubothrium rugosum in the burbot (Lota lota) have been performed in... 相似文献