全文获取类型
收费全文 | 28093篇 |
免费 | 628篇 |
国内免费 | 4546篇 |
专业分类
安全科学 | 1147篇 |
废物处理 | 1427篇 |
环保管理 | 2781篇 |
综合类 | 10454篇 |
基础理论 | 5616篇 |
环境理论 | 12篇 |
污染及防治 | 8314篇 |
评价与监测 | 1467篇 |
社会与环境 | 1440篇 |
灾害及防治 | 609篇 |
出版年
2023年 | 244篇 |
2022年 | 683篇 |
2021年 | 598篇 |
2020年 | 416篇 |
2019年 | 457篇 |
2018年 | 668篇 |
2017年 | 747篇 |
2016年 | 827篇 |
2015年 | 925篇 |
2014年 | 1318篇 |
2013年 | 2347篇 |
2012年 | 1411篇 |
2011年 | 1788篇 |
2010年 | 1317篇 |
2009年 | 1388篇 |
2008年 | 1511篇 |
2007年 | 1360篇 |
2006年 | 1250篇 |
2005年 | 976篇 |
2004年 | 867篇 |
2003年 | 942篇 |
2002年 | 865篇 |
2001年 | 928篇 |
2000年 | 730篇 |
1999年 | 691篇 |
1998年 | 511篇 |
1997年 | 513篇 |
1996年 | 516篇 |
1995年 | 490篇 |
1994年 | 407篇 |
1993年 | 372篇 |
1992年 | 308篇 |
1991年 | 299篇 |
1990年 | 260篇 |
1989年 | 223篇 |
1988年 | 212篇 |
1987年 | 173篇 |
1986年 | 175篇 |
1985年 | 159篇 |
1984年 | 178篇 |
1983年 | 177篇 |
1982年 | 182篇 |
1981年 | 146篇 |
1980年 | 132篇 |
1979年 | 123篇 |
1978年 | 134篇 |
1977年 | 115篇 |
1976年 | 103篇 |
1975年 | 107篇 |
1974年 | 118篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
851.
Ernest J. Kulik Joseph P. Lingle Thomas A. Nowlan Rickie G. Nesbit 《补救:环境净化治理成本、技术与工艺杂志》1996,6(4):51-66
For both private corporations and military branches, downsizing and consolidation are becoming more commonplace. A range of environmental concerns must be addressed to effectively implement a consolidation program. A facility deactivation program can often become a minefield for an organization. Responsible personnel are typically inexperienced with the process, and this can lead to costly mistakes. This article provides insight into this topic based on experience gained with a multifacility program and related environmental issues. It emphasizes the importance of detailed, up-front, proactive project planning; a solid program management system; and accurate identification of project objectives and deliverables. 相似文献
852.
亭子口库区水质汞的污染特征及建库后水体中汞的预测 总被引:1,自引:1,他引:1
亭子口水利枢纽位于喜陵江平流苍溪县城以上,15km处。本文根据嘉陵江广元段水质监测资料,分析库区地面水体中汞的现状污染特征,并运用沉积物的负指数方程预测库区建坝后水体中汞的浓度。 相似文献
853.
Summary Quantitative studies on the biomethanation processes using a different biomass (goat dung, cow dung, buffalo dung, piggery waste, poultry waste and sewage) alone or in combination have been made. The dung samples have been found to be an efficient producer of biogas at a 1:2 dilution. Better yields of biogas are obtained in combination with other biomasses rather than when used alone. Judicious mixing of biomasses, however, is important. Competitive biomethanation of a biomass by other biomasses as a source for a wild population of microbes has been studied in vials using a cross-inoculation technique, i.e. using inoculum of one biomass on different sterile biomasses. The results show that the microbes are very specific and usually non-adaptive. Each inoculum outclasses others in using its natural biomass for methanation but reacts poorly when inoculated to other alien biomasses. Buffalo dung is to some extent adaptive in nature.Professor S.C. Lahiri is the senior author of this paper and he is ex-Head of the Department of Chemistry at the University of Kalyani where Nilanjan Chakravorty is a research fellow. Dr G.M. Sarkar is a senior lecturer in the Department of Botany at Ranaghat College, Ranaghat, Nadia, West Bengal, India. 相似文献
854.
Hydropower,adaptive management,and Biodiversity 总被引:2,自引:0,他引:2
Adaptive management is a policy framework within which an iterative process of decision making is followed based on the observed responses to and effectiveness of previous decisions. The use of adaptive management allows science-based research and monitoring of natural resource and ecological community responses, in conjunction with societal values and goals, to guide decisions concerning man's activities. The adaptive management process has been proposed for application to hydropower operations at Glen Canyon Dam on the Colorado River, a situation that requires complex balancing of natural resources requirements and competing human uses. This example is representative of the general increase in public interest in the operation of hydropower facilities and possible effects on downstream natural resources and of the growing conflicts between uses and users of river-based resources. This paper describes the adaptive management process, using the Glen Canyon Dam example, and discusses ways to make the process work effectively in managing downstream natural resources and biodiversity. 相似文献
855.
Adaptive management: Promises and pitfalls 总被引:3,自引:1,他引:3
Proponents of the scientific adaptive management approach argue that it increases knowledge acquisition rates, enhances information flow among policy actors, and provides opportunities for creating shared understandings. However, evidence from efforts to implement the approach in New Brunswick, British Columbia, Canada, and the Columbia River Basin indicates that these promises have not been met. The data show that scientific adaptive management relies excessively on the use of linear systems models, discounts nonscientific forms of knowledge, and pays inadequate attention to policy processes that promote the development of shared understandings among diverse stakeholders. To be effective, new adaptive management efforts will need to incorporate knowledge from multiple sources, make use of multiple systems models, and support new forms of cooperation among stakeholders. 相似文献
856.
857.
858.
ABSTRACT: There are a large number of conceptual hydrological models available today. It is not easy to immediately identify the similarities and differences between the different models. The Swedish HBV model and the Chinese Xinanjiang model are two examples of conceptual, semi-distributed, rainfall-runoff models. The Xinanjiang model was designed for use in humid and semi-humid regions, with no routine for the snowmelt runoff, whereas the snow routine is an important part of the HBV model in many applications. The model structures of the two models may be described in four routines, compared in this paper. The integral structures of them are similar, but there are some differences, especially in the runoff production routine. The physical significance and physical definitions of some model parameters were analyzed. Both models were tested in two basins. Both models gave similar results, and both models performed well in the application. The similarity of the results obtained by different model structures leads to the following two conclusions. First, more effort should probably be spent on the improvement of input data quality and coverage than on the development of more detailed model structures only. Second, inference about basin behavior and characteristics from the values of calibrated model parameters must be made with great caution. 相似文献
859.
用灰色模型预测我国铁路水害发展趋势 总被引:2,自引:0,他引:2
根据近15a来我国铁路水害年断道时间和断道次数的数据特点,将不同程度水害年分为三个等级。在此基础上,建立了铁路水害的灰色预测模型。并用此模型预测了近期铁路水害大小和远期的发展趋势。这对于我国铁路水害防治的宏观决策具有指导意义。 相似文献
860.
土氡测量在地质灾害勘测中的干扰实验研究 总被引:2,自引:0,他引:2
对土氡勘测中来自测量过程、勘测场地条件、气象因素方面的常见干扰进行了实验研究,探讨了干扰机理,指出了定性及部分定量排除干扰的方法。 相似文献