全文获取类型
收费全文 | 17150篇 |
免费 | 66篇 |
国内免费 | 61篇 |
专业分类
安全科学 | 200篇 |
废物处理 | 1123篇 |
环保管理 | 1858篇 |
综合类 | 2160篇 |
基础理论 | 4836篇 |
环境理论 | 11篇 |
污染及防治 | 4131篇 |
评价与监测 | 1595篇 |
社会与环境 | 1320篇 |
灾害及防治 | 43篇 |
出版年
2023年 | 83篇 |
2022年 | 218篇 |
2021年 | 238篇 |
2020年 | 122篇 |
2019年 | 132篇 |
2018年 | 1593篇 |
2017年 | 1535篇 |
2016年 | 1466篇 |
2015年 | 379篇 |
2014年 | 427篇 |
2013年 | 642篇 |
2012年 | 895篇 |
2011年 | 1778篇 |
2010年 | 1009篇 |
2009年 | 893篇 |
2008年 | 1276篇 |
2007年 | 1561篇 |
2006年 | 347篇 |
2005年 | 345篇 |
2004年 | 371篇 |
2003年 | 368篇 |
2002年 | 324篇 |
2001年 | 171篇 |
2000年 | 89篇 |
1999年 | 87篇 |
1998年 | 51篇 |
1997年 | 52篇 |
1996年 | 42篇 |
1995年 | 62篇 |
1994年 | 52篇 |
1993年 | 19篇 |
1992年 | 32篇 |
1991年 | 38篇 |
1990年 | 31篇 |
1989年 | 28篇 |
1988年 | 20篇 |
1987年 | 21篇 |
1986年 | 34篇 |
1985年 | 24篇 |
1984年 | 34篇 |
1983年 | 28篇 |
1982年 | 24篇 |
1981年 | 18篇 |
1980年 | 16篇 |
1979年 | 16篇 |
1966年 | 20篇 |
1965年 | 13篇 |
1958年 | 11篇 |
1957年 | 11篇 |
1956年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
111.
Gamergates (i.e. mated reproductive workers) are mostly known from ant species within the Ponerinae. We report here the discovery of gamergates in two species of the subfamily Myrmicinae. Until now, mated reproductive females in colonies of myrmicine species have been considered morphologically distinct from the worker caste. However, in two species of the myrmicine Metapone (Metapone madagascarica and a newly discovered, not yet described Metapone species) all workers have six ovarioles and a spermatheca; and some of them are mated. There are no morphological differences between mated and non-mated workers. Field observations and laboratory studies indicate that colonies of the Metapone species can reproduce with gamergates only. 相似文献
112.
Although amphibians are highly vocal, they generally emit only a limited number of acoustic communication signals. We report here the extraordinarily rich vocal repertoire of Amolops tormotus, a ranid species in China. These frogs produce countless vocalizations, some of which share features of birdsong or primate calls, e.g., ultrasonic frequency components, multiple upward and downward FM sweeps, and sudden onset and offset of selective harmonic components within a call note. Frame-by-frame video analysis of the frog's calling behavior suggests the presence of two pairs of vocal sacs that may contribute to the remarkable call-note complexity in this species. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at http://dx.doi.org/10.1007/s00114-002-0335-x. 相似文献
113.
Aysen Müezzinoğlu Tolga Elbir Abdurrahman Bayram 《Environmental Engineering and Policy》1998,1(2):109-116
In this study, an inventory of air pollutant emission estimates from major air polluting sources in Turkey for period between 1985 and 2005 with 5-year intervals were estimated. Inventory covers anthropogenic sources of five major air pollutants of particulate matter, sulfur dioxide, carbon monoxide, nitrogen oxides and non-methane volatile organic compounds. Their break-down with respect to main activity sectors were shown and their distribution by the largest industrial source categories were worked out as annual estimates. This inventory and its analysis point to serious environmental implications of air pollutants and a need to develop a policy plan for reducing these emissions. 相似文献
114.
115.
116.
117.
We report relatively high citrulline concentration in amniotic fluid of a citrullinemic fetus suggesting that prenatal detection of this condition could be done on this basis in conjunction with a direct or an indirect determination of argininosuccinate synthetase activity in amniotic fluid cells. 相似文献
118.
The larvae and pupae of the ladybird Thalassa saginata develop inside colonies of the dolichoderine ant Dolichoderus bidens. This association is the first specific and obligatory relationship recorded between ants and ladybirds. The ants provide shelter and protection to the larvae but the diet of the latter remains unclear. The integration of T. saginata larvae into the ant colonies is achieved by mimicking the cuticular patterns of the ants brood. Moreover, the larvae secrete substances from their hairs and anal gland that are likely to enhance their attractiveness. 相似文献
119.
Caching or storing surplus prey may reduce the risk of starvation during periods of food deprivation. While this behaviour occurs in a variety of birds and mammals, it is infrequent among invertebrates. However, golden orb-web spiders, Nephila edulis, incorporate a prey cache in their relatively permanent web, which they feed on during periods of food shortage. Heavier spiders significantly reduced weight loss if they were able to access a cache, but lost weight if the cache was removed. The presence or absence of stored prey had no effect on the weight loss of lighter spiders. Furthermore, N. edulis always attacked new prey, irrespective of the number of unprocessed prey in the web. In contrast, females of Argiope keyserlingi, who build a new web every day and do not cache prey, attacked fewer new prey items if some had already been caught. Thus, a necessary preadaptation to the evolution of prey caching in orb-web spiders may be a durable or permanent web, such as that constructed by Nephila. 相似文献
120.
Independent teams undertook environmental monitoring of particular concentrations of major construction projects forming part of Hong Kong’s U.S. $20 billion airport infrastructure programme located in dense urban areas. The team combination of environmental specialists with experienced civil engineers enabled pragmatic mitigation measures to be developed and accepted by the construction personnel with the result that potentially significant adverse impacts were averted. The authors discuss the mechanism and success of this innovative approach. 相似文献