全文获取类型
收费全文 | 25657篇 |
免费 | 231篇 |
国内免费 | 243篇 |
专业分类
安全科学 | 666篇 |
废物处理 | 892篇 |
环保管理 | 3321篇 |
综合类 | 5989篇 |
基础理论 | 6100篇 |
环境理论 | 9篇 |
污染及防治 | 6397篇 |
评价与监测 | 1568篇 |
社会与环境 | 1058篇 |
灾害及防治 | 131篇 |
出版年
2022年 | 178篇 |
2018年 | 308篇 |
2017年 | 313篇 |
2016年 | 458篇 |
2015年 | 369篇 |
2014年 | 576篇 |
2013年 | 1882篇 |
2012年 | 709篇 |
2011年 | 954篇 |
2010年 | 741篇 |
2009年 | 851篇 |
2008年 | 949篇 |
2007年 | 1005篇 |
2006年 | 903篇 |
2005年 | 766篇 |
2004年 | 748篇 |
2003年 | 779篇 |
2002年 | 692篇 |
2001年 | 961篇 |
2000年 | 640篇 |
1999年 | 443篇 |
1998年 | 280篇 |
1997年 | 298篇 |
1996年 | 329篇 |
1995年 | 344篇 |
1994年 | 356篇 |
1993年 | 290篇 |
1992年 | 326篇 |
1991年 | 335篇 |
1990年 | 349篇 |
1989年 | 319篇 |
1988年 | 299篇 |
1987年 | 248篇 |
1986年 | 251篇 |
1985年 | 270篇 |
1984年 | 247篇 |
1983年 | 260篇 |
1982年 | 263篇 |
1981年 | 266篇 |
1980年 | 222篇 |
1979年 | 223篇 |
1978年 | 226篇 |
1977年 | 195篇 |
1976年 | 213篇 |
1975年 | 178篇 |
1974年 | 227篇 |
1973年 | 195篇 |
1972年 | 198篇 |
1971年 | 173篇 |
1967年 | 201篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
The past two decades have witnessed an increase in the exploration for, and development of, mineral resources at Arctic latitudes. Such effort has resulted in the commencement of production at a number of different localities in close proximity to the ocean. Since proximity to a source of transportation for the conveyance of concentrates to the market is a primary requirement governing the economic decisions for the mine to proceed, it is logical that ore deposits near a coastline are primary targets for development.
Closely tied to coastal mining developments is the need to dispose of tailings and waste rock in the most economical manner. Prior to the advent of heightened public awareness and environmental concern, and the enactment of pollution legislation, disposal practices were largely based upon convenience. Currently, however, proposed disposal and operating practices receive closer scrutiny, with a view to providing adequate protection for aquatic resources and habitat. This paper summarizes some of the features of three Arctic mines, wastes from which enter the marine environment, and compares the disposal practices used at each to measures of environmental change as indicated by metal concentrations in various media. 相似文献
Closely tied to coastal mining developments is the need to dispose of tailings and waste rock in the most economical manner. Prior to the advent of heightened public awareness and environmental concern, and the enactment of pollution legislation, disposal practices were largely based upon convenience. Currently, however, proposed disposal and operating practices receive closer scrutiny, with a view to providing adequate protection for aquatic resources and habitat. This paper summarizes some of the features of three Arctic mines, wastes from which enter the marine environment, and compares the disposal practices used at each to measures of environmental change as indicated by metal concentrations in various media. 相似文献
12.
13.
14.
15.
16.
17.
Geochemical characteristics of surficial sediments in the Panangad region of Cochin estuary, the largest brackish-water humid ecosystem in the south-west coast of India, were analysed. Temporal variations in nutrient stoichiometry, seasonal characteristics of redox elements Fe and S, and the phosphorus geochemistry were employed for the purpose. The stoichiometric analysis pointed towards autochthonous origin of organic matter, possibility of nitrogen limitation, and allochthonous modification of redox conditions. Seasonal variations were not statistically significant for all the geochemical parameters, whereas significant spatial variations were observed with lower values at sandy stations, suggesting that the texture of the sediments is the main factor influencing the sediment geochemistry. Significant inter-relations between the geochemical parameters also suggest a common control mechanism. Based on these geochemical characteristics, the study region can be effectively categorized into two distinct zones, viz. (1) erosion and transportation and (2) deposition zones. 相似文献
18.
This paper examines the relationship between survivor reactions to a downsizing and retention subsequent to a downsizing. We hypothesize that survivors who experience the downsizing as distributively, procedurally, and interactionally just and who see top management as trustworthy will feel more attached to the organization because each reduces the threat inherent in downsizing. In addition, we hypothesize that survivors who feel empowered will also feel more attached to the organization because they feel better able to cope with the downsizing. We further hypothesize that those survivors who feel more attached to the organization following the downsizing will be more likely to remain with the organization in the coming year. The theoretical model is tested on a sample of aerospace employees who survived an organizational downsizing. The trustworthiness of management, distributive justice, procedural justice, and three dimensions of empowerment are found to facilitate more organizational attachment. Higher levels of attachment are found, in turn, to facilitate less voluntary turnover in the year following the downsizing. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
19.
David W. Mehlman 《Conservation biology》1994,8(4):1141-1145
20.