全文获取类型
收费全文 | 18449篇 |
免费 | 173篇 |
国内免费 | 289篇 |
专业分类
安全科学 | 386篇 |
废物处理 | 858篇 |
环保管理 | 1763篇 |
综合类 | 2973篇 |
基础理论 | 4379篇 |
环境理论 | 8篇 |
污染及防治 | 5013篇 |
评价与监测 | 1452篇 |
社会与环境 | 1991篇 |
灾害及防治 | 88篇 |
出版年
2023年 | 131篇 |
2022年 | 296篇 |
2021年 | 311篇 |
2020年 | 172篇 |
2019年 | 221篇 |
2018年 | 411篇 |
2017年 | 451篇 |
2016年 | 603篇 |
2015年 | 422篇 |
2014年 | 686篇 |
2013年 | 1524篇 |
2012年 | 754篇 |
2011年 | 938篇 |
2010年 | 709篇 |
2009年 | 738篇 |
2008年 | 965篇 |
2007年 | 968篇 |
2006年 | 764篇 |
2005年 | 667篇 |
2004年 | 661篇 |
2003年 | 602篇 |
2002年 | 549篇 |
2001年 | 607篇 |
2000年 | 412篇 |
1999年 | 235篇 |
1998年 | 165篇 |
1997年 | 174篇 |
1996年 | 176篇 |
1995年 | 226篇 |
1994年 | 178篇 |
1993年 | 144篇 |
1992年 | 151篇 |
1991年 | 160篇 |
1990年 | 161篇 |
1989年 | 135篇 |
1988年 | 121篇 |
1987年 | 114篇 |
1986年 | 120篇 |
1985年 | 119篇 |
1984年 | 124篇 |
1983年 | 106篇 |
1982年 | 120篇 |
1981年 | 103篇 |
1980年 | 99篇 |
1979年 | 95篇 |
1978年 | 68篇 |
1976年 | 68篇 |
1975年 | 67篇 |
1973年 | 71篇 |
1972年 | 88篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
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
42.
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
43.
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
44.
Riviane R. Hora Claudie Doums Chantal Poteaux Renée Fénéron Jorge Valenzuela Jürgen Heinze Dominique Fresneau 《Behavioral ecology and sociobiology》2005,59(2):285-292
Social parasites exploit the worker force of colonies of other social insects to rear their own young. Social parasitism occurs in several Hymenoptera and is particularly common in several tribes of the ant subfamilies Myrmicinae and Formicinae. Here, we document the occurrence of miniaturized queens (microgynes) in colonies of Ectatomma tuberculatum, an ant belonging to the subfamily Ectatomminae. Behavioral observations and genetic analyses show that microgynes concentrate their reproductive efforts almost exclusively on the production of sexual offspring (microgynes and males), whereas the regular, large queens (macrogynes) produce workers in addition to sexuals. According to mitochondrial and nuclear markers, gene flow between microgynes and macrogynes is extremely limited. Whereas the co-occurrence of microgynes and macrogynes in the related species Ectatomma ruidum constitutes an intraspecific polymorphism associated with alternative dispersal tactics, microgynes found in colonies of E. tuberculatum appear to be a distinct species and to represent the first case of social parasitism in the poneromorph subfamilies of ants. 相似文献
45.
46.
V. Thomas Parker 《Conservation biology》2002,16(5):1444-1446
47.
48.
Schuller P Iroumé A Walling DE Mancilla HB Castillo A Trumper RE 《Journal of environmental quality》2006,35(5):1756-1763
Rapid and reliable methods for documenting soil erosion associated with forest harvest operations are needed to support the development of best management practices for soil and water conservation. To address this need, the potential for using 7Be measurements to estimate patterns and amounts of soil redistribution associated with individual post-harvest events was explored. The 7Be technique, which was originally developed for use on agricultural land, was employed to estimate soil redistribution associated with a period of heavy rainfall within a harvested forest area located in the Lake Region of Chile (39 degrees 44'7' S, 73 degrees 10'39' W; 22% slope; and mean annual rainfall 2300 mm yr(-1)). The results provided by the 7Be technique were validated against direct measurements of soil gain or loss during the same period obtained using erosion pins. The information produced by the two approaches was similar. The results of this study demonstrate the potential for using 7Be measurements to document event-based erosion in recently harvested forest areas. 相似文献
49.
Russian Journal of Ecology - 相似文献
50.