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   857篇
  免费   15篇
  国内免费   17篇
安全科学   32篇
废物处理   33篇
环保管理   176篇
综合类   102篇
基础理论   182篇
环境理论   1篇
污染及防治   226篇
评价与监测   88篇
社会与环境   31篇
灾害及防治   18篇
  2023年   8篇
  2022年   8篇
  2021年   18篇
  2020年   11篇
  2019年   5篇
  2018年   22篇
  2017年   26篇
  2016年   25篇
  2015年   13篇
  2014年   36篇
  2013年   66篇
  2012年   36篇
  2011年   53篇
  2010年   51篇
  2009年   40篇
  2008年   51篇
  2007年   42篇
  2006年   53篇
  2005年   36篇
  2004年   30篇
  2003年   35篇
  2002年   26篇
  2001年   23篇
  2000年   14篇
  1999年   11篇
  1998年   14篇
  1997年   8篇
  1996年   15篇
  1995年   12篇
  1994年   17篇
  1993年   9篇
  1992年   4篇
  1991年   9篇
  1990年   2篇
  1989年   5篇
  1988年   5篇
  1987年   3篇
  1986年   2篇
  1985年   6篇
  1984年   6篇
  1983年   7篇
  1982年   8篇
  1981年   2篇
  1980年   2篇
  1978年   3篇
  1973年   2篇
  1971年   1篇
  1966年   1篇
  1964年   1篇
  1956年   2篇
排序方式: 共有889条查询结果,搜索用时 46 毫秒
81.
82.
This study investigates the relationship between characteristics of environmental policy statements and the reputations of ISO 14001 registrars who had performed certification audits of firms operating in mainland China. Three characteristics of environmental policy statements were examined: (1) The conformance of the policy to strict interpretations of the international standard; (2) The policy statement's adherence to the good practice guidelines specified in ISO 14004; and, (3) Self-reported evaluations of the policy statement's effectiveness as implemented. Data from 106 facilities in Beijing, Shanghai and Guangzhou reveal that registrar quality has a relatively weak, positive relationship with conformance to both ISO 14001 standards and to ISO 14004 guidelines, but no relationship was observed with the self-reported data. Additional findings are that the use of foreign registrars is significantly associated with the adoption of ISO 14004 guidelines and that conformance with ISO 14001 standards is somewhat higher for international joint ventures and foreign-owned firms than for state-owned enterprises.  相似文献   
83.
Two novel solid-state 13C nuclear magnetic resonance (NMR) spectroscopic techniques, PSRE (proton spin relaxation editing) and RESTORE [Restoration of Spectra via T(CH) and T(1rho)H (T One Rho H) Editing], were used to provide detailed chemical characterization of the organic matter from six Australian sewage sludges. These methods were used to probe the submicrometer heterogeneity of sludge organic matter, and identify and quantify spatially distinct components. Analysis of the T1H relaxation behavior of the sludges indicated that each sludge contained two types of organic domains. Carbon-13 PSRE NMR subspectra were generated to determine the chemical nature of these domains. The rapidly relaxing component of each sludge was rich in protein and alkyl carbon, and was identified as dead bacterial material. The slowly relaxing component of each sludge was rich in carbohydrate and lignin structures, and was identified as partly degraded plant material. The bacterial domains were shown, using the RESTORE technique, to also have characteristically rapid T(1rho)H relaxation rates. This rapid T(1rho)H relaxation was identified as the main cause of underrepresentation of these domains in standard 13C cross polarization (CP) NMR spectra of sludges. The heterogeneous nature of sewage sludge organic matter has implications for land application of sewage sludge, since the two components are likely to have different capacities for sorbing organic and inorganic toxicants present in sewage sludge, and will decompose at different rates.  相似文献   
84.
An Interstate Technology and Regulatory Council (ITRC) forum was recently held that focused on six case studies in which bioremediation of dense nonaqueous‐phase liquids (DNAPLs) was performed; the objective was to demonstrate that there is credible evidence for bioremediation as a viable environmental remediation technology. The first two case studies from the forum have been previously published; this third case study involves a pilot‐scale demonstration that investigated the effects of biological activity on enhancing dissolution of an emplaced tetrachloroethene (PCE) DNAPL source. It used a controlled‐release test cell with PCE as the primary DNAPL in a porous media groundwater system. Both laboratory tests and a field‐scale pilot test demonstrated that bioaugmentation can stimulate complete dechlorination to a nontoxic end product and that the mass flux from a source zone increases when biological dehalorespiration activity is enhanced through nutrient (electron donor) addition and bioaugmentation. All project goals were met. Important achievements include demonstrating the ability to degrade a PCE DNAPL source to ethene and obtaining significant information on the impacts to the microbial populations and corresponding isotope enrichments during biodegradation of a source area. © 2007 Wiley Periodicals, Inc.  相似文献   
85.
86.
87.
Eucalyptus forest; and in the composition of understorey herbs, sedges, and grasslands. Pollen concentration and charcoal and organic content also exhibit post-European changes. Thus, pollen analysis provides a technique for determining changes in sediment budgets and identifying major vegetation changes in floodplains.  相似文献   
88.
89.
90.
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