全文获取类型
收费全文 | 36692篇 |
免费 | 410篇 |
国内免费 | 319篇 |
专业分类
安全科学 | 1217篇 |
废物处理 | 1769篇 |
环保管理 | 4827篇 |
综合类 | 5308篇 |
基础理论 | 9697篇 |
环境理论 | 10篇 |
污染及防治 | 9314篇 |
评价与监测 | 2586篇 |
社会与环境 | 2477篇 |
灾害及防治 | 216篇 |
出版年
2022年 | 344篇 |
2021年 | 367篇 |
2020年 | 238篇 |
2019年 | 292篇 |
2018年 | 539篇 |
2017年 | 554篇 |
2016年 | 871篇 |
2015年 | 640篇 |
2014年 | 1002篇 |
2013年 | 3006篇 |
2012年 | 1225篇 |
2011年 | 1651篇 |
2010年 | 1341篇 |
2009年 | 1411篇 |
2008年 | 1718篇 |
2007年 | 1640篇 |
2006年 | 1515篇 |
2005年 | 1315篇 |
2004年 | 1247篇 |
2003年 | 1251篇 |
2002年 | 1160篇 |
2001年 | 1436篇 |
2000年 | 994篇 |
1999年 | 629篇 |
1998年 | 469篇 |
1997年 | 478篇 |
1996年 | 493篇 |
1995年 | 578篇 |
1994年 | 482篇 |
1993年 | 425篇 |
1992年 | 458篇 |
1991年 | 447篇 |
1990年 | 429篇 |
1989年 | 422篇 |
1988年 | 369篇 |
1987年 | 299篇 |
1986年 | 293篇 |
1985年 | 318篇 |
1984年 | 337篇 |
1983年 | 314篇 |
1982年 | 332篇 |
1981年 | 280篇 |
1980年 | 215篇 |
1979年 | 234篇 |
1978年 | 196篇 |
1977年 | 175篇 |
1975年 | 178篇 |
1974年 | 165篇 |
1973年 | 212篇 |
1972年 | 175篇 |
排序方式: 共有10000条查询结果,搜索用时 20 毫秒
51.
Cultural heritage is being addressed by a number of charters and conventions and it is clear that its consideration within decision-making processes is progressively becoming a real challenge, both for developers and public authorities. Against this background, this paper reviews the environmental assessment framework developed by the European Community, as this should increasingly influence decision making about cultural heritage in an urban setting. The legislative framework for access to environmental information is also reviewed because of its relevance to the decision-making process.The Directives on Environmental Impact Assessment and Strategic Environmental Assessment both require a consideration of cultural heritage in decision making. This requirement can go some way to addressing the paradox in the European Community's position whereby the community wishes to conserve and enhance its own cultural identity whilst, at the same time, cultural heritage is usually defined at a local level. The present paper suggests that, given their flexibility, the two European Community directives on environmental assessment constitute a promising opportunity to address this seeming paradox, but that there is a significant gap between legal obligations and the methodological tools to meet them. 相似文献
52.
Mfon T.Udo 《环境科学学报(英文版)》2002,14(4)
Aspects of the trophic attributes of the mudskipper,Periophthalmus barbarus occurring in the mangrove swamps of ImoRiver estuary, Nigeria, were investigated during a 12-month period(April, 1992-March, 1993). Feeding intensity increased with size;it was higher in the dry season (November-April) than in the wetseason (May-October); monthly changes in the indices of feedingintensity were significantly correlated. Major food objectscomprised detritus and benthic algae; crustaceans, insects,macrophyte matter and sand grains were minor food objects whilefish, molluscs, Chilopoda, nematodes and fungi were unconsciouslydevoured objects. Diet varied seasonally; algae and sesarmid crabswere generally more in the dry season than during the rains whereasFPOM and fish increased in the wet over dry season. The mudskipperdisplay a high degree of euryphagy and can be considered as ageneralist and an omnivore. The lower trophic status of P. barbarusqualifies it as a good aquaculture candidate. Food richness washigher in big-sized class (BSC) than small-sized class (SSC).Size-based and seasonal variations were not apparent in foodrichness. Diet breadth was higher in the BSC than the SSC; therewas dry season increase in diet breadth. 相似文献
53.
54.
55.
56.
57.
58.
This work, carried out within the framework of the PRISMA II project, aims at evaluating the effects of the Po River flow on primary productivity, measured by C with in situ sample incubations. A total of four cruises was carried out in late winter and early summer (1996-1998) along transects from the coast offshore. In both seasons, the highest primary productivity was found in the most oligohaline stations. The effects of the Po River inputs were therefore clearly evident in the westernmost area, both in high productivity values and in the shape of productivity profiles. In late winter, extensive blooms of Skeletonema costatum and Pseudo-nitzschia delicatissima resulted in productivity values that were sometimes higher than in early summer. In early summer 1996, greatly reduced river flow clearly influenced productivity which was much lower than in 1997. 相似文献
59.
Four introduced and one aboriginal species of the genus Pinus L. have been studied in the middle taiga subzone of southern Karelia. Significant interspecific differences in the dates of onset, cessation, and peak of the growth of shoots and needles have been revealed. It has been shown that their annual increment depends on the rate of growth, rather than on its duration. The dynamics of shoot and needle growth in introduced and aboriginal species, though largely similar, differ in some respects. These differences reflect species-specific responses to hydrothermal conditions in a certain growing season. 相似文献
60.
Russian Journal of Ecology - 相似文献