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   599篇
  免费   11篇
  国内免费   7篇
安全科学   31篇
废物处理   32篇
环保管理   165篇
综合类   54篇
基础理论   138篇
污染及防治   144篇
评价与监测   37篇
社会与环境   13篇
灾害及防治   3篇
  2023年   2篇
  2021年   5篇
  2020年   2篇
  2019年   8篇
  2018年   6篇
  2017年   10篇
  2016年   16篇
  2015年   10篇
  2014年   8篇
  2013年   72篇
  2012年   16篇
  2011年   25篇
  2010年   29篇
  2009年   28篇
  2008年   23篇
  2007年   27篇
  2006年   34篇
  2005年   17篇
  2004年   20篇
  2003年   25篇
  2002年   20篇
  2001年   13篇
  2000年   12篇
  1999年   15篇
  1998年   16篇
  1997年   6篇
  1996年   16篇
  1995年   11篇
  1994年   16篇
  1993年   9篇
  1992年   4篇
  1991年   6篇
  1990年   7篇
  1989年   6篇
  1988年   6篇
  1987年   3篇
  1986年   4篇
  1985年   4篇
  1984年   8篇
  1983年   5篇
  1982年   8篇
  1981年   6篇
  1980年   8篇
  1979年   7篇
  1978年   4篇
  1977年   3篇
  1976年   2篇
  1975年   3篇
  1974年   2篇
  1973年   2篇
排序方式: 共有617条查询结果,搜索用时 922 毫秒
51.
52.
Abstract: Opportunities for the development of an amalgam of park and leisure-oriented commercial establishments in urban-core waterfont settings exist in many U.S. cities. Public awareness of the need to enhance the environmental quality of these waterfont areas has resulted in a demand for planning and implementation action. However, the lack of understanding of urban political systems has been an inhibiting factor in the development of this park/ business concept. The major factors that influence the decision-making process leading to the development of urban-core waterfronts for park/business use are identified inthis paper. Understanding this decision-making process can aid project implementation and avoid waste of planning effort in time, dollars, and productivity.  相似文献   
53.
ABSTRACT: An important enforcement question is, “What should be the relationship between ‘Best Management Practices’ (BMP) and receiving-water standards?” Nonpoint pollution dischargers are concerned about implementing a BMP program, only to find themselves in violation because receiving-water standards still have not been met. They are also concerned about the procedures a regulatory agency will utilize to determine the relative success of a BMP program. Successful management of nonpoint pollution requires that these concerns be addressed. Three alternative relationships have been developed. The recommended alternative is to implement the BMP program and use standards as a measure of the effectiveness of the program. Failure to achieve the standards would lead to a reevaluation of the BMP program. Enforcement activities against nonpoint dischargers would be restricted to the failure on their part to implement the previously agreed upon BMP program. Recommendations are also made as to measures regulatory agencies should take if their procedures to judge the relative success of a BMP program are to be technically and politically effective.  相似文献   
54.
ABSTRACT: Data splitting is used to compare methods of determining “homogeneous” hydrologic regions. The methods compared use cluster analysis based on similarity of hydrologic characteristics or similarity of characteristics of a stream's drainage basin. Data for 221 stations in Arizona are used to show that the methods, which are a modification of DeCoursey's scheme for defining regions, improve the fit of estimation data to the model, but that is is necessary to have an independent measure of predictive accuracy, such as that provided by data splitting, to demonstrate improved predictive accuracy. The methods used the complete linkage algorithm for cluster analysis and computed weighted average estimates of hydrologic characteristics at ungaged sites.  相似文献   
55.
56.

Objective

Genomics Quality Assessment has provided external quality assessments (EQAs) for preimplantation genetic testing (PGT) for 12 years for eight monogenic diseases to identify sub-optimal PGT strategies, testing and reporting of results, which can be shared with the genomics community to aid optimised standards of PGT services for couples.

Method

The EQAs were provided in two stages to mimic end-to-end protocols. Stage 1 involved DNA feasibility testing of a couple undergoing PGT and affected proband. Participants were required to report genotyping results and outline their embryo testing strategy. Lymphoblasts were distributed for mock embryo testing for stage 2. Submitted clinical reports and haplotyping results were assessed against peer-ratified criteria. Performance was monitored to identify poor performance.

Results

The most common testing methodology was short tandem repeat linkage analysis (59%); however, the adoption of single nucleotide polymorphism-based platforms was observed and a move from blastomere to trophectoderm testing. There was a variation in testing strategies, assigning marker informativity and understanding test limitations, some clinically unsafe. Critical errors were reported for genotyping and interpretation.

Conclusion

EQA provides an overview of the standard of preimplantation genetic testing-M clinical testing and identifies areas of improvement for accurate detection of high-risk embryos.  相似文献   
57.
58.
59.
60.
Cemeteries as Repositories of Natural and Cultural Diversity   总被引:1,自引:0,他引:1  
  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