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   1360篇
  免费   24篇
  国内免费   3篇
安全科学   47篇
废物处理   53篇
环保管理   279篇
综合类   124篇
基础理论   392篇
环境理论   1篇
污染及防治   327篇
评价与监测   83篇
社会与环境   70篇
灾害及防治   11篇
  2022年   8篇
  2021年   10篇
  2020年   16篇
  2019年   12篇
  2018年   25篇
  2017年   12篇
  2016年   44篇
  2015年   30篇
  2014年   34篇
  2013年   125篇
  2012年   35篇
  2011年   67篇
  2010年   48篇
  2009年   60篇
  2008年   56篇
  2007年   71篇
  2006年   57篇
  2005年   52篇
  2004年   40篇
  2003年   44篇
  2002年   45篇
  2001年   39篇
  2000年   27篇
  1999年   26篇
  1998年   18篇
  1997年   20篇
  1996年   20篇
  1995年   34篇
  1994年   19篇
  1993年   20篇
  1992年   13篇
  1991年   25篇
  1990年   19篇
  1989年   15篇
  1988年   9篇
  1987年   16篇
  1986年   15篇
  1985年   11篇
  1984年   25篇
  1983年   10篇
  1982年   14篇
  1981年   9篇
  1980年   9篇
  1979年   9篇
  1978年   6篇
  1977年   12篇
  1975年   9篇
  1974年   8篇
  1973年   5篇
  1971年   7篇
排序方式: 共有1387条查询结果,搜索用时 15 毫秒
371.
372.
This paper demonstrates that Bishop's formulation deviates in a fundamental way from our model and, in so doing, Bishop has assumed the problem away. Bishop utilizes a utility function that is too general to discriminate the time pattern of consumption from that of production. Hence, the intertemporal nature of the goods that we analyzed cannot be captured by Bishop's representation. Furthermore, we show that current benefit cost methods that discount the benefit stream of a public asset are Pareto intertemporally inefficient.  相似文献   
373.
ABSTRACT: Bivalves are used as bioindicators to assess trends of the chemical quality of coastal and marine environments due to their ability to concentrate chemicals. These shellfish are subject to seasonal physiological changes influencing the chemical concentration. Using quarterly data, we model concentration via linear regression with a biologically based seasonal component. This was applied to cadmium concentration measured in the blue mussel (Mytilus edulis) at three sites in the Seine estuary (Normandy, France). In this case we have a high concentration season from January to June and a “low concentration” season from July to December. This season definition was checked a posteriori, using box-and-whisker plots and a statistical test of comparison of pair-wise adjusted least-squares mean differences, and it appears to be very reasonable. We averaged data by season and across sites. Our final model (R2= 0.846 with N= 27 observations) includes highly significant terms: a season effect, which accounts for 45% of the total variability, a linear and a quadratic time term. Outliers were identified by high Studentized residual values and attributed to bias in the temporal sampling schemes. The methodology developed will further be used with other shellfish and/or other trace elements and organic chemicals.  相似文献   
374.
ABSTRACT: A study of 222Rn concentrations in the water distribution system of Tucson, Arizona, revealed levels of 60 to 1260 pCi/L in domestic waters. These measurements are comparable to levels of between 80 and 1400 pCi/l for 222Rn found in ground water samples in the North-Central Tucson basin (Kahn et al., 1994). Estimated loss of 222Rn due to radioactive decay during travel from the well head to the home ranges from 8 to 50 percent.  相似文献   
375.
Regulatory agencies are involved in analysis of plans for, and results of, virtually every environmental site investigation and remediation project. Controlling the cost of such projects is largely dependent on arriving at a reasonable scope of work. Regulatory approval is heavily influenced by the approach, cooperation, level of expertise, communication skills, preparation, and diplomacy of those who interact directly with agency personnel. Agencies also can be sources of assistance in obtaining the cooperation of other responsible parties. This article discusses a practical approach to maximize assistance, cooperation, and collaboration from regulatory agencies.  相似文献   
376.
The responses of ecological computer simulations are significantly changed by the inclusion of human behavior patterns. Two computer simulations illustrate this principle for internal and external decision making. The Northwest Educational Trawler Simulation (NETS) models the interaction between fish populations, fishing effort, markets, and a fishing community. This simulation includes an internal decision making submodel for changing fishing effort based on observed behaviors of fishermen. NOGERO, a simulation of a mythical coastal fishing culture, uses external decision making where simulation users act as stewards. The patterns of model response vary depending on the attitudes and goals of decision makers. This shows how human behavior interacts with ecosystem dynamics to produce a variety of results.  相似文献   
377.
Fishery management concepts incorporate a number of value judgements about what social goals are right for a fishery. These value judgements result in optimizing some goals over others. Since the public, fishermen, and consumers weight goals differently than managers, frustration and conflict result. The correspondence between social goals specified by the public and those inherent in management concepts needs to be evaluated.  相似文献   
378.
ABSTRACT: In Ontario no major studies have been attempted in the area of water-oriented recreation to guide planned development. To fill this gap a comprehensive investigation was undertaken on a group of lakes in the District of Muskoka, one of the premier tourist regions of the province. This paper presents the results of this study which focusses on the lake environment, recreational activities, attitudes, and perceptions of the cottagers.  相似文献   
379.
It is commonly claimed that increased use of pulverised fuel ash (pfa) and ground granulated blast-furnace slag in concrete as partial replacement for Portland cement can have economic, amenity and technical advantages. Many factors need to be considered is such an analysis and this paper is offered as a contribution to the debate of this issue, and not as a definite solution. In the long-term the major benefit may be in the savings of the energy that would otherwise be required for increased production of Portland cement.  相似文献   
380.
ABSTRACT. Temperature recorder data from central Lake Superior obtained from May through July, 1967, are used to describe the spring warming of this deep lake. Data from the 30, 91 and 150 m levels suggest that water descending in the thermal bar spreads lakeward, filling the lake with an increasingly thick layer of maximum density water. Lakeward of the thermal bar, local warming is relatively slow preceeding and following the passage of the reverse thermocline at a given level.  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