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   2971篇
  免费   220篇
  国内免费   735篇
安全科学   312篇
废物处理   150篇
环保管理   368篇
综合类   1777篇
基础理论   731篇
环境理论   1篇
污染及防治   283篇
评价与监测   146篇
社会与环境   121篇
灾害及防治   37篇
  2024年   9篇
  2023年   57篇
  2022年   95篇
  2021年   109篇
  2020年   136篇
  2019年   115篇
  2018年   99篇
  2017年   105篇
  2016年   124篇
  2015年   137篇
  2014年   195篇
  2013年   233篇
  2012年   243篇
  2011年   266篇
  2010年   226篇
  2009年   176篇
  2008年   146篇
  2007年   238篇
  2006年   190篇
  2005年   153篇
  2004年   117篇
  2003年   122篇
  2002年   105篇
  2001年   105篇
  2000年   81篇
  1999年   76篇
  1998年   46篇
  1997年   38篇
  1996年   31篇
  1995年   27篇
  1994年   22篇
  1993年   21篇
  1992年   24篇
  1991年   10篇
  1990年   17篇
  1989年   4篇
  1988年   2篇
  1987年   2篇
  1986年   2篇
  1984年   4篇
  1983年   1篇
  1982年   3篇
  1981年   3篇
  1980年   2篇
  1979年   2篇
  1978年   1篇
  1976年   1篇
  1973年   1篇
  1972年   1篇
  1971年   3篇
排序方式: 共有3926条查询结果,搜索用时 62 毫秒
71.
针对安全性评价过程评价周期长,工作量大,手段落后等问题,依据安全检查表法及评价理论,以Microsoft Visual Basic6.0为开发工具,开发了火力发电厂安全性评价计算机辅助系统,在企业局域网中实现,可以减少安全评价过程中大量重复工作,提高效率,其它行业也可以基于此方法,开发相应的计算机辅助评价系统。  相似文献   
72.
针对目前水资源短缺状况,以齐鲁石化热电厂为例提出了利用生活污水,养鱼场排水、锅炉排污水以及化学反洗水作循环冷却水补充水的优化方案,并就废水田用方案的实施及运行中发现的问题进行了分析与探讨。  相似文献   
73.
在综合调查省内各火电厂废水处理系统运行现状的基础上,总结了各类废水处理系统的特点及其运行中存在的问题,提出了改进意见。  相似文献   
74.
在安全评价中,人因失误特别是事故后人因失误越来越受到重视;但相对而言,事故前人因失误没有引起足够的重视。本通过对大量核电厂安全分析报告和运行事件报告的考察,系统地阐述了事故前人因失误对系统安全的显影响,并在此基础上,归纳出在核电站开展事故前人因(失误)分析的程序。该程序主要包括系统熟悉,定性分析,筛选,定量计算,与故障树的集成,敏感性分析与不确定性分析,形成分析档等几个步骤。  相似文献   
75.
关于污水处理厂质量监理工作的探讨   总被引:2,自引:0,他引:2  
污水处理已引起我国政府的高度重视。以此为契机,通过对阳江市第一净水厂工程监理工作的回顾,初步探讨了污水处理厂质量监理工作。  相似文献   
76.
神州煤电焦化股份公司焦化厂调整思路,探索出一套“以人为本,重在落实”的基层车间管理办法,通过实践,证明该方法是行之有效的,使该厂形成了互相监督、互相制约的良好安全氛围。  相似文献   
77.
Subsidence is a primary factor governing marsh deterioration in Mississippi River deltaic plain coastal marshes. Marsh surface-water level relationships are maintained primarily through soil organic matter accumulation and inorganic sediment input. In this study we examined the role of soil organic matter accumulation in maintaining marsh elevation in a brackish Spartina patens marsh. Measured rates of soil organic accumulation were compared to plant biomass production and soil respiration (carbon dioxide and methane emission) at the study sites. The study demonstrated the importance of plant biomass production to soil organic carbon accumulation in maintaining viable Spartina patens marshes in sediment-deficient coastal environments. The role of Mississippi River freshwater reintroduction in maintaining conditions for organic accretion is discussed.  相似文献   
78.
ABSTRACT: The Ecosystem Management (EM) process belongs to the category of Multi‐Criteria Decision Making (MCDM) problems. It requires appropriate decision support systems (DSS) where “all interested people” would be involved in the decision making process. Environmental values critical to EM, such as the biological diversity, health, productivity and sustainability, have to be studied, and play an important role in modeling the ecosystem functions; human values and preferences also influence decision making. Public participation in decision and policy making is one of the elements that differentiate EM from the traditional methods of management. Here, a methodology is presented on how to quantify human preferences in EM decision making. The case study of the National Park of River Nestos Delta and Lakes Vistonida and Ismarida in Greece, presented as an application of this methodology, shows that the direct involvement of the public, the quantification of its preferences and the decision maker's attitude provide a strong tool to the EM decision making process. Public preferences have been given certain weights and three MCDM methods, namely, the Expected Utility Method, Compromise Programming and the Analytic Hierarchy Process, have been used to select alternative management solutions that lead to the best configuration of the ecosystem and are also socially acceptable.  相似文献   
79.
ABSTRACT: Ground water contamination by excess nitrate leaching in row‐crop fields is an important issue in intensive agricultural areas of the United States and abroad. Giant cane and forest riparian buffer zones were monitored to determine each cover type's ability to reduce ground water nitrate concentrations. Ground water was sampled at varying distances from the field edge to determine an effective width for maximum nitrate attenuation. Ground water samples were analyzed for nitrate concentrations as well as chloride concentrations, which were used as a conservative ion to assess dilution or concentration effects within the riparian zone. Significant nitrate reductions occurred in both the cane and the forest riparian buffer zones within the first 3.3 m, a relatively narrow width. In this first 3.3 m, the cane and forest buffer reduced ground water nitrate levels by 90 percent and 61 percent, respectively. Approximately 40 percent of the observed 99 percent nitrate reduction over the 10 m cane buffer could be attributed to dilution by upwelling ground water. Neither ground water dilution nor concentration was observed in the forest buffer. The ground water nitrate attenuation capabilities of the cane and forest riparian zones were not statistically different. During the spring, both plant assimilation and denitrification were probably important nitrate loss mechanisms, while in the summer nitrate was more likely lost via denitrification since the water table dropped below the rooting zone.  相似文献   
80.
This paper deals with the mechanical properties and degree of swelling (DS) of starch/PVA blend film with the functional groups i.e., hydroxyl and carboxyl group, of additives. Starch/PVA blend films were prepared by using the mixing process. Glycerol (GL) with 3 hydroxyl group, sorbitol (SO) with 6 hydroxyl group, succinic acid (SA) with 2 carboxyl group, malic acid (MA) with 1 hydroxyl and 2 carboxyl group, tartaric acid (TA) with 2 hydroxyl and 2 carboxyl group and citric acid (CA) with 1 hydroxyl and 3 carboxyl group were used as additives. The results of measured tensile strength (TS) and elongation (%E) verified that both hydroxyl and carboxyl group as a functional groups increased the flexibility and strength of the film. Values of DS for GL-added and SA-added films were low. However, DS values of the films added MA, TA or CA with both hydroxyl and carboxyl group were comparatively high. When the film was dried at low temperature, the properties of the films were evidently improved. The reason is probably because the hydrogen bonding was activated at low temperature.  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