全文获取类型
收费全文 | 2370篇 |
免费 | 262篇 |
国内免费 | 702篇 |
专业分类
安全科学 | 400篇 |
废物处理 | 35篇 |
环保管理 | 256篇 |
综合类 | 1490篇 |
基础理论 | 418篇 |
环境理论 | 1篇 |
污染及防治 | 129篇 |
评价与监测 | 57篇 |
社会与环境 | 363篇 |
灾害及防治 | 185篇 |
出版年
2024年 | 19篇 |
2023年 | 65篇 |
2022年 | 132篇 |
2021年 | 123篇 |
2020年 | 126篇 |
2019年 | 128篇 |
2018年 | 105篇 |
2017年 | 128篇 |
2016年 | 132篇 |
2015年 | 124篇 |
2014年 | 113篇 |
2013年 | 156篇 |
2012年 | 208篇 |
2011年 | 216篇 |
2010年 | 156篇 |
2009年 | 160篇 |
2008年 | 122篇 |
2007年 | 173篇 |
2006年 | 138篇 |
2005年 | 143篇 |
2004年 | 102篇 |
2003年 | 99篇 |
2002年 | 71篇 |
2001年 | 52篇 |
2000年 | 69篇 |
1999年 | 43篇 |
1998年 | 40篇 |
1997年 | 39篇 |
1996年 | 26篇 |
1995年 | 24篇 |
1994年 | 29篇 |
1993年 | 14篇 |
1992年 | 11篇 |
1991年 | 6篇 |
1990年 | 12篇 |
1989年 | 5篇 |
1988年 | 6篇 |
1987年 | 1篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1972年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有3334条查询结果,搜索用时 421 毫秒
991.
992.
993.
推进环保产业结构调整的思考 总被引:2,自引:0,他引:2
文章对环保产业结构调整要解决的问题进行了分析,指出产业结构调整必须符合市场经济要求的布局和流通结构,只有建立现代化的企业制度,企业才能有活力。 相似文献
994.
995.
王彬辉 《中国环境管理干部学院学报》2000,(2)
长期以来,我国对排污或超标排污实行征收排污费制度。九届人大常委会第13次会议修订通过的《海洋环境保护法》对此进行了改革。本文对此进行了深入分析。 相似文献
996.
997.
The structure of the crown and branching; the growth, development, and ontogeny of branches; and organogenesis and growth of female shoots in the model Siberian stone pine trees were studied in four types of habitats at the timberline in the central Altai Mountains (1700–2170 m a.s.l.). The results provided evidence that the ecological forms of trees appear due to changes in the pattern of branching as well as to the decreased rate of vegetative (primarily apical) growth. The diameter of the shoot pith is one of the most variable characters reflecting the deterioration of environmental conditions at higher elevations. 相似文献
998.
Flower variability was studied in natural populations of European starflower (Trientalis europaeaL.). The results showed that the flower structure in this species is determined by two parameters: the multiplicity of primordia of flower components and the uniformity of flower meristem development. The frequencies of nonuniformly developing flowers differs depending on the habitat. It appears that both parameters are largely determined by random fluctuations. 相似文献
999.
Results of stationary studies on the spatial location of sables (Martes zibellinaL.) belonging to different age and sex groups are summarized. Mapping the sites where 388 animals were taken, it was found that young animals tended to live near floodplains; adult animals, on watersheds. Analysis of sables taken by commercial hunters (n= 1833) made it possible to estimate the age composition and the degree and spatial distribution of the hunting pressure on sable populations in three areas of the Ob region. The spatial separation of young and reproductive animals is interpreted as a group adaptive response to the specific distribution pattern of different habitats typical of this species and to the pattern of animal elimination. It is proposed to use the specific pattern of animal distribution for maintaining the size of the population that is subject to hunting. Specifically, reserve (reproductive) territories should be organized in watershed areas. 相似文献
1000.
The idea that natural selection can be meaningfully applied at the group level may be more important than previously thought. This perspective, a modern version of group selection, is called multilevel selection. Multilevel selection theory could incorporate previous explanations for the evolution of cooperation including kin selection. There is general agreement that natural selection favors noncooperators over cooperators in the case of an unstructured population. Therefore, the evolution of cooperation by multilevel selection often requires positive assortment between cooperators and noncooperators. The question is how this positive assortment can arise in the ecological meaning. We constructed an individual-based model of multilevel selection and introduced migration and evolution. The results showed that positive assortment was generated especially when a migration strategy was adopted in which individuals respond specifically to bad environmental conditions. It was also shown that the founder effect in the evolutionary process could further facilitate positive assortment by working with migration. We analyzed assortment by using relatedness defined in group-structured populations. The fact that cooperation was achieved by such migration and by the founder effect highlights the importance of sensitiveness to the ecological environment and of fluctuations in group size, respectively. 相似文献