全文获取类型
收费全文 | 11853篇 |
免费 | 191篇 |
国内免费 | 1580篇 |
专业分类
安全科学 | 368篇 |
废物处理 | 608篇 |
环保管理 | 1220篇 |
综合类 | 3212篇 |
基础理论 | 2654篇 |
环境理论 | 1篇 |
污染及防治 | 3527篇 |
评价与监测 | 752篇 |
社会与环境 | 1073篇 |
灾害及防治 | 209篇 |
出版年
2023年 | 121篇 |
2022年 | 312篇 |
2021年 | 228篇 |
2020年 | 161篇 |
2019年 | 186篇 |
2018年 | 290篇 |
2017年 | 314篇 |
2016年 | 375篇 |
2015年 | 364篇 |
2014年 | 557篇 |
2013年 | 1058篇 |
2012年 | 602篇 |
2011年 | 676篇 |
2010年 | 542篇 |
2009年 | 612篇 |
2008年 | 656篇 |
2007年 | 621篇 |
2006年 | 517篇 |
2005年 | 441篇 |
2004年 | 402篇 |
2003年 | 422篇 |
2002年 | 395篇 |
2001年 | 446篇 |
2000年 | 336篇 |
1999年 | 245篇 |
1998年 | 228篇 |
1997年 | 168篇 |
1996年 | 184篇 |
1995年 | 200篇 |
1994年 | 155篇 |
1993年 | 140篇 |
1992年 | 138篇 |
1991年 | 107篇 |
1990年 | 98篇 |
1989年 | 82篇 |
1988年 | 81篇 |
1987年 | 80篇 |
1986年 | 58篇 |
1985年 | 65篇 |
1984年 | 65篇 |
1983年 | 61篇 |
1982年 | 60篇 |
1981年 | 71篇 |
1980年 | 47篇 |
1979年 | 48篇 |
1977年 | 40篇 |
1976年 | 36篇 |
1974年 | 35篇 |
1973年 | 43篇 |
1972年 | 51篇 |
排序方式: 共有10000条查询结果,搜索用时 328 毫秒
11.
12.
We examined the impact of seven species of mobile mushroom corals (Fungiidae) on the community structure of sheltered reef slopes in terms of their patterns of migration, habitat use and competition with other benthic organisms. On fringing reefs at Eilat, Red Sea, polyps detached at 1 to 6 cm length, and grew to 11–55 cm length. Attached mushroom corals were oriented vertically in reef cavities. Detached corals migrated downward on the reef slope and onto rubble or soft substratum at the reef base, at 29 to 71 cmyr–1. Mobility decreased with corallum size and extent of undersurface ornamentation. In aquaria, small corals righted themselves and migrated up to 6 cm d–1 by nocturnally inflating and pushing their tissues against the substratum. Autonomous coral behavior and storm-generated water motion appeared to account for most fungiid mobility at Eilat. Mushroom corals did not damage each other upon contact, even in multi-species aggregations, but unilaterally damaged non-fungiid scleractinian corals. Their dominance during contact interactions retards overgrowth by larger attached scleractinians, and mobility allows them to colonize soft substrata not accessible to most other reef corals. 相似文献
13.
14.
15.
16.
Daytime sampling of mangrove and seagrass (Halophila/Halodule community) habitats every 7 wk at Alligator Creek, Queensland, Australia, over a period of 13 mo (February 1985–February
1986) using two types of seine net, revealed distinct mangrove and seagrass fish and crustacean faunas. Total abundance of
fish and relative abundance of small and large fish also varied between habitats and seasonally. Post-larval, juvenile and
small adult fish captured with a small seine-net (3 mm mesh) were significantly more abundant (4 to 10 times) in the mangrove
habitat throughout the 13 mo of sampling. Mangrove fish abundance showed significant seasonality, greatest catches being recorded
in the warm, wet-season months of the year. Relative abundances of larger fish (captured in a seine net with 18 mm mesh) in
the two habitats varied throughout the year, but did not show a seasonal pattern. At the same site, small crustaceans were
significantly more abundant in the mangroves in all but one dryseason sample. Similar comparisons for three riverine sites,
sampled less frequently, in the dry and wet seasons of 1985 and 1986, respectively, showed that in general mangrove habitats
had significantly more fish per sample, although the relative abundance of fish in mangroves and other habitats changed with
season. Crustacean catches showed a similar pattern, except that densities among sites changed with season. Fish and crustacean
abundance in mangroves varied among sites, indicating that estuaries differ in their nursery-ground value. The juveniles of
two commercially important penaeid prawn species (Penaeus merguiensis and Metapenaeus ensis) were amongst the top three species of crustaceans captured in the study, and both were significantly more abundant in the
mangrove habitat. By contrast, mangroves could not be considered an important nursery for juveniles of commercially important
fish species in northern Australia. However, based on comparisons of fish catches in other regions, the results of the present
study indicate the importance of mangroves as nursery sites for commercially exploited fish stocks elsewhere in South-East
Asia.
Contribution No. 378 from the Australian Institute of Marine Science 相似文献
17.
Data on the existence of a specific system regulating the growth, size, and structure of enterobacterial populations are first summarized in terms of the chemical ecology concept formulated by S.S. Shvarts. The role of this system in transgene functioning is described using the example of the lux operon integrated into Escherichia coli. A relatively simple test for estimating such interactions is proposed.Translated from Ekologiya, No. 2, 2005, pp. 91–96.Original Russian Text Copyright © 2005 by Pshenichnov, Maslennikova, Nikitina. 相似文献
18.
Fritz Nüßlein Ernst Anton Feicht Sigurd Schulte-Hostede Antonius Kettrup 《Environmental Sciences Europe》1997,9(3):136-142
A site contaminated by mercury serves as an example for evaluating the environmental medicine aspects of mercury emissions on individuals living in the surroundings. Based on defined, conventional scenarios, estimations of internal exposure were made for seven different age groups and with regard to such contact media as soil, air and food. Using human monitoring methods, an attempt was made to compare the epidemiological results. The site-specific and pathway-specific estimation of exposure is based on a multitude of various samples as well as on measurements of concentrations in the compartments relevant for intake. As based upon rigid guideline values, both these calculations and the epidemiological investigations reveal a slight increase in the mercury exposure. 相似文献
19.
20.