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   18341篇
  免费   192篇
  国内免费   165篇
安全科学   532篇
废物处理   759篇
环保管理   2570篇
综合类   2470篇
基础理论   4905篇
环境理论   4篇
污染及防治   5293篇
评价与监测   1188篇
社会与环境   852篇
灾害及防治   125篇
  2022年   126篇
  2021年   160篇
  2020年   103篇
  2019年   146篇
  2018年   249篇
  2017年   252篇
  2016年   411篇
  2015年   356篇
  2014年   515篇
  2013年   1562篇
  2012年   603篇
  2011年   793篇
  2010年   615篇
  2009年   725篇
  2008年   831篇
  2007年   894篇
  2006年   780篇
  2005年   648篇
  2004年   672篇
  2003年   623篇
  2002年   620篇
  2001年   761篇
  2000年   566篇
  1999年   313篇
  1998年   238篇
  1997年   226篇
  1996年   274篇
  1995年   273篇
  1994年   256篇
  1993年   232篇
  1992年   210篇
  1991年   190篇
  1990年   207篇
  1989年   191篇
  1988年   183篇
  1987年   176篇
  1986年   149篇
  1985年   148篇
  1984年   176篇
  1983年   177篇
  1982年   170篇
  1981年   169篇
  1980年   138篇
  1979年   161篇
  1978年   109篇
  1977年   102篇
  1976年   90篇
  1975年   94篇
  1973年   94篇
  1972年   101篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
431.
In order to evaluate the leading and lagging effects of process safety climate on incidents, we correlated safety climate survey data with organizational safety records from before and after the survey time period. We obtained data from a large, multinational organization with manufacturing operations involving a number of complex processes, chemicals, and hazardous substances. A total of 7728 employees from 62 sites responded to a safety climate survey in 2007. Individual responses were aggregated to the site-level and matched to site-level organizational records of process safety incidents 1 year before and 1 year after survey administration. Employees’ perceptions of good routine housekeeping were significantly related to environmental impact incidents as both a leading and a lagging indicator, as well as fires/explosions and property damage outcomes. Employees’ perceptions of systems to prevent backlogs and the extent to which health and safety problems are promptly corrected were also related to environmental releases and fires/explosions. Implications for process safety climate research, organizational survey strategies, and organizational climate change are discussed.  相似文献   
432.
Due to the amounts of chromium in the leachate resulting from leather leaching tests, chromium sulfate tanned leather wastes are very often considered hazardous wastes. To overcome this problem, one option could be recovering the chromium and, consequently, lowering its content in the leather scrap. With this objective, chromium leather scrap was leached with sulfuric acid solutions at low temperature also aiming at maximizing chromium removal with minimum attack of the leather matrix. The effects of leather scrap dimension, sulfuric acid and sodium sulfate concentration in the solutions, as well as extraction time and temperature on chromium recovery were studied, and, additionally, organic matrix degradation was evaluated. The best conditions found for chromium recovery were leather scrap conditioning using 25 mL of concentrated H2SO4/L solution at 293 or 313 K during 3 or 6 days. Under such conditions, 30–60 ± 5% of chromium was recovered and as low as 3–6 ± 1% of the leather total organic carbon (TOC) was dissolved. Using such treatment, the leather scrap area and volume are reduced and the residue is a more brittle material showing enhanced anaerobic biodegradability. Although good recovery results were achieved, due to the fact that the amount of chromium in eluate exceeded the threshold value this waste was still hazardous. Thus, it needs to be methodically washed in order to remove all the chromium de-linked from collagen.  相似文献   
433.
434.
In order to determine what effects human activities have on natural processes, it is important to thoroughly understand those processes. Unfortunately, we know little about what natural processes are operating, and even less about how they have functioned historically. This paper discusses the importance of natural processes in affecting surface water acidification and the necessity for developing quantitative estimates of natural, as well as anthropogenic, contributions to the acidification of surface waters. A review of the literature and the analysis of chemistry data from six limed lakes in New York and Massachusetts have identified a number of possible processes that may play important roles in acidifying surface waters. At present, these processes are poorly understood and require further research. Once we have such knowledge, we will be able to clearly see the effects of human activities on natural processes and modify those activities in ways that will mitigate negative impact in a predictable manner.  相似文献   
435.
436.
Biogenic volatile organic compounds (BVOCs) play an important role in atmospheric chemistry and the carbon cycle. Isoprene is quantitatively the most important of the non-methane BVOCs (NMBVOCs), with an annual emission of about 400–600 TgC; about 90% of this is emitted by terrestrial plants. Incorporating a mechanistic treatment of isoprene emissions within land-surface schemes has recently become a focus for the modelling community, the aim being to quantify the potential magnitude of associated climate feedbacks. However, these efforts are hampered by major uncertainties about why plants emit isoprene and the relative importance of different environmental controls on isoprene emission. The availability and reliability of observations of isoprene fluxes from different types of vegetation is limited, and this also imposes constraints on model development. Nevertheless, progress is being made towards the development of mechanistic models of isoprene emission which, in conjunction with atmospheric chemistry models, will ultimately allow improved quantification of the feedbacks between the terrestrial biosphere and climate under past and future climate states.  相似文献   
437.
438.
Most of the mitigation measures against natural hazards can not be perfectly allocated via the common market mechanism, given their principle character of being a public good. Thus, different instruments need to be applied to retrieve their values. Economic valuation tools are one alternative to estimate preferences of individuals towards these goods. These methods are often difficult to operationalise and are not a feasible task for every single project. An alternative is offered by direct preference representation through involving affected interest groups actively in decisions. A critical question is whether the decision on protection measures can be left to public participation or should remain in the experts’ decision responsibility. It can be observed that the latter mode shows inefficiencies. In this paper, it is argued that participation could be one way to bring about the desired goal of increasing efficiency. The present work offers a discussion of the relevant political economic concepts in order to introduce the idea that participation can increase efficiency through achieving the Pareto criterion claimed in the realm of constitutional economics. Furthermore it will be shown that decision aiding tools, namely multi-criteria analysis, can integrate participation into actual decision making processes in a structured way.  相似文献   
439.
440.
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