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   204篇
  免费   5篇
安全科学   20篇
废物处理   5篇
环保管理   55篇
综合类   14篇
基础理论   48篇
污染及防治   45篇
评价与监测   14篇
社会与环境   5篇
灾害及防治   3篇
  2023年   2篇
  2020年   1篇
  2018年   1篇
  2016年   3篇
  2015年   3篇
  2014年   2篇
  2013年   27篇
  2012年   7篇
  2011年   6篇
  2010年   2篇
  2009年   5篇
  2008年   12篇
  2007年   3篇
  2006年   9篇
  2005年   5篇
  2004年   7篇
  2003年   6篇
  2002年   9篇
  2001年   8篇
  2000年   4篇
  1999年   7篇
  1998年   3篇
  1997年   2篇
  1996年   5篇
  1995年   1篇
  1993年   1篇
  1992年   4篇
  1991年   5篇
  1990年   1篇
  1989年   5篇
  1988年   1篇
  1987年   1篇
  1986年   6篇
  1985年   2篇
  1984年   2篇
  1983年   2篇
  1982年   4篇
  1981年   1篇
  1980年   2篇
  1979年   6篇
  1978年   4篇
  1977年   4篇
  1976年   3篇
  1975年   2篇
  1974年   3篇
  1973年   2篇
  1972年   2篇
  1971年   2篇
  1968年   1篇
  1966年   2篇
排序方式: 共有209条查询结果,搜索用时 31 毫秒
161.
Environmental Management - Cat ownership is increasing globally, representing a growing threat to urban wildlife. Although some cities have policies and strategies for managing owned cats, the...  相似文献   
162.
The outcomes of species recovery programs have been mixed; high‐profile population recoveries contrast with species‐level extinctions. Each conservation intervention has its own challenges, but to inform more effective management it is imperative to assess whether correlates of wider recovery program success or failure can be identified. To contribute to evidence‐based improvement of future conservation strategies, we conducted a global quantitative analysis of 48 mammalian recovery programs. We reviewed available scientific literature and conducted semistructured interviews with conservation professionals involved in different recovery programs to investigate ecological, management, and political factors associated with population recoveries or declines. Identifying and removing threats was significantly associated with increasing population trend and decreasing conservation dependence, emphasizing that populations are likely to continue to be compromised in the absence of effective threat mitigation and supporting the need for threat monitoring and adaptive management in response to new and potential threats. Lack of habitat and small population size were cited as limiting factors in 56% and 42% of recovery programs, respectively, and both were statistically associated with increased longer term dependence on conservation intervention, demonstrating the importance of increasing population numbers quickly and restoring and protecting habitat. Poor stakeholder coordination and management were also regularly cited by respondents as key weaknesses in recovery programs, indicating the importance of effective leadership and shared goals and management plans. Project outcomes were not influenced by biological or ecological variables such as body mass or habitat, which suggests that these insights into correlates of conservation success and failure are likely to be generalizable across mammals.  相似文献   
163.
We examined whether job engagement mediated the effects of organizational justice dimensions on work behaviors and attitudes. Considering distributive and procedural justice from a motivational perspective, we proposed that job engagement would mediate these two dimensions' relations with the work outcomes of task performance, organizational citizenship behavior, and job satisfaction. We also expected this mediation effect would be magnified when senior management trust (SMT) was high. Our results showed that the simple mediation model was supported only for distributive justice. Alternatively, the indirect effect of procedural justice on work outcomes through job engagement was significant only when SMT was high. Implications of our findings and areas for future research are discussed. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
164.
Alteration of DNA methylation is a major epigenetic mechanism associated with the effects of nongenotoxic carcinogens. We evaluated the effects of two environmental pollutants, hexabromocyclododecane (HBCD), 17-beta oestradiol (E(2)) as well as 5-aza 2' deoxycytidine (5AdC) on global DNA methylation levels (5-methyl 2' deoxycytidine) in the liver and gonads of the three-spine stickleback (Gasterosteus aculeatus). HBCD at 30 and 300 ng/L of water did not produce statistically significant differences in global genomic methylation in liver of female stickleback. On the other hand, the methylation inhibitor, 5-aza-2'-deoxycytidine, significantly lowered hepatic global methylation levels in these fish by 14% (P<0.05). The naturally occurring oestrogen, 17-beta oestradiol (E(2)) at 100 ng/L also decreased global DNA methylation levels in female liver but this effect was not statistically significant. In contrast, both E(2) and 5AdC caused statistically significant (P<0.001 and P<0.01 respectively) global genomic hypermethylation in the gonads of male sticklebacks although the increase seen in the female gonads was not statistically significant. The male gonad effect though unexplained may potentially be an indirect response to hypomethylation in other tissues (such as the liver) and may have important implications regarding oestrogenic effects in fish. The contrasting effects of HBCD and E(2) on global DNA methylation in stickleback should contribute to the integrated risk assessment of these environmental chemicals.  相似文献   
165.
166.
The Critical Review on Toxic Substances in the Atmospheric Environment was presented by Bernard D. Goldstein at the 76th Annual Meeting of the Air Pollution Control Association in Atlanta, Georgia. Dr. Goldstein summarized his paper, which had been published in the May 1983 issue of JAPCA. Prepared discussions presented at the Critical Review Session are reproduced here. In addition, comments made from the floor and through the mails have been formalized and are published along with closing remarks by Dr. Goldstein. Dr. Paul J. Lioy served as Moderator for the 1983 Critical Review Session.  相似文献   
167.
TSI Inc. (Shoreview, MN) has introduced three new water-based condensation particle counters (WCPCS) that were designed to detect airborne particles larger than 2.5 nm (model 3786), 5 nm (model 3785), and either 10 or 20 nm (model 3782). These WCPCs are well suited for real-time, environmental monitoring of number concentration of airborne ultrafine particles. Their unique design incorporates the use of water as the working fluid instead of alcohol. Water is odor free, readily available, and eliminates the problem of water condensation and absorption into alcohol working fluids during operation in humid environments. In this study, the performance of three TSI WCPCs was characterized for several aerosol compositions, including sucrose, salt (NaCl), dioctyl sebacate (DOS), dioctyl phthalate (DOP), emery oil (poly-alpha-olefin), silver, impurity residue particles, and ambient aerosol particles. All particles were size selected using a nano differential mobility analyzer (nano-DMA; model 3085, TSI Inc.) to create monodisperse challenge aerosols. The challenge aerosol was mixed uniformly with clean makeup flow and split into a WCPC and a reference instrument to determine the counting efficiency of the WCPC. For the model 3785 WCPC, the D50 (i.e., the particle diameter with 50% counting efficiency) was determined to be 3.1 nm for salt particles, 4.7 nm for sucrose and ambient particles, 5.6 nm for silver particles, and >50 nm for ultrapure oil particles. The sensitivity to oil droplets increased dramatically (D50 < 10 nm) when the oil was slightly contaminated. The D50 of model 3786 ultrafine water-based CPC (UWCPC) was 2.4 nm for impurity residue particles. The D50 of the model 3782 WCPC was 10.8 (with a nominal setting of 10 nm) or 19.8 nm (with a nominal setting of 20 nm) for sucrose particles. All three WCPCs have response times of less than 2 or 3 sec and are therefore able to detect fast-changing events.  相似文献   
168.
A reclamation demonstration project at an abandoned deep mine   总被引:1,自引:0,他引:1  
This project involves an evaluation of the reclamation process at a typical abandoned deep coal mine in the Midwest, U.S.A. The reclamation process included determining the final land use, collection of preconstruction environmental data, development of detailed construction plans, and implementation of the construction plans. A multidisciplinary approach is being used to evaluate post-construction conditions of the site. Current investigations are monitoring groundwater, surface water quality, aquatic ecosystems, revegetation, soil characteristics, erosion and runoff, soil microbial populations, wildlife, and economic effects of the reclamation. Data collected to date indicate a significant improvement in overall environmental quality, a substantial increase in the economic potential of the site and adjacent properties, and a genuine enhancement of the entire area's aesthetic value. This project will also provide design data for future reclamation efforts of this type.This project is financially supported by the following agencies: U.S. Department of Energy, Contract No. W31-109-Eng-38; Abandoned Mined Land Reclamation Council, State of Illinois Contract No. 31-109-38-3694L; Illinois Institute of Natural Resources, Contract No. 31-109-38-3702L.  相似文献   
169.
The Science of Nature - The establishment of a carbon cycle was a necessary prerequisite for the evolution of higher forms of life. This could not have been achieved without the direct...  相似文献   
170.
ABSTRACT This paper describes the change in the macrophyte community caused by dredging a small Wisconsin lake. In water depths up to 1.5 m, revegetation was rapid after dredging. The plant community changed from one dominated by large-leafed Potamogeton (pondweed), Megalodonta beckii (water marigold), and Elodea canadensis (waterweed) to one dominated by Chara (stonewort), Najas flexilis (naiad), and Myriophyllum (milfoil). Plant growth ended at the 4 m depth and growth recovered much more slowly in water depths between 1.5 and 4 m. The area between 1.5 m and 2.5 m in particular supported a monotypic milfoil stand after dredging.  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