全文获取类型
收费全文 | 24311篇 |
免费 | 357篇 |
国内免费 | 616篇 |
专业分类
安全科学 | 755篇 |
废物处理 | 1065篇 |
环保管理 | 3372篇 |
综合类 | 4152篇 |
基础理论 | 6179篇 |
环境理论 | 7篇 |
污染及防治 | 6293篇 |
评价与监测 | 1524篇 |
社会与环境 | 1771篇 |
灾害及防治 | 166篇 |
出版年
2023年 | 145篇 |
2022年 | 289篇 |
2021年 | 262篇 |
2020年 | 244篇 |
2019年 | 239篇 |
2018年 | 402篇 |
2017年 | 405篇 |
2016年 | 588篇 |
2015年 | 468篇 |
2014年 | 661篇 |
2013年 | 2019篇 |
2012年 | 846篇 |
2011年 | 1208篇 |
2010年 | 942篇 |
2009年 | 1030篇 |
2008年 | 1148篇 |
2007年 | 1207篇 |
2006年 | 980篇 |
2005年 | 840篇 |
2004年 | 860篇 |
2003年 | 805篇 |
2002年 | 759篇 |
2001年 | 926篇 |
2000年 | 697篇 |
1999年 | 408篇 |
1998年 | 279篇 |
1997年 | 301篇 |
1996年 | 309篇 |
1995年 | 374篇 |
1994年 | 290篇 |
1993年 | 273篇 |
1992年 | 252篇 |
1991年 | 263篇 |
1990年 | 249篇 |
1989年 | 242篇 |
1988年 | 210篇 |
1987年 | 199篇 |
1986年 | 199篇 |
1985年 | 201篇 |
1984年 | 241篇 |
1983年 | 197篇 |
1982年 | 221篇 |
1981年 | 216篇 |
1980年 | 171篇 |
1979年 | 192篇 |
1978年 | 122篇 |
1977年 | 127篇 |
1974年 | 125篇 |
1973年 | 124篇 |
1972年 | 138篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
221.
The prenatal diagnosis of The Turner Syndrome is described at a menstrual age of 12 weeks. Detection of cystic hygroma was followed by vaginal chorionic villous sampling (CVS) which revealed a 45,X karyotype. Early documentation of fetal karyotype in the presence of a cystic hygroma is essential for accurate diagnosis and genetic counselling. 相似文献
222.
M. R. Verschraegen-Spae N. Van Roy A. De Perdigo A. De Paepe F. Speleman 《黑龙江环境通报》1993,13(5):385-394
The nature and origin of two de novo small marker chromosomes found at prenatal diagnosis were determined by fluorescence in situ hybridization using chromosome centromere-specific probes and chromosome-specific plasmid libraries. One marker was found in a mosaic state and was shown to be an i(18p). The second marker was characterized as an inv dup(22). We conclude that molecular cytogenetic analysis contributes to the identification of marker chromosomes and therefore facilitates genetic counselling and decision-making for the parents. 相似文献
223.
224.
225.
M. Blunck W. -D. Busse G. Meister E. Möller A. Mullen L. A. A. van Rooijen 《Die Naturwissenschaften》1989,76(3):96-98
Online searching in publically available patent files opens up interesting possibilities to provide a rapid response to critical questions. A computerized analysis of all patents of leading German pharmaceutical companies over the last decade in important indication areas is described. Supported by subsequent manual processing of individual patents it is shown that duplicate experiments on animals practically never occur. 相似文献
226.
This study investigated the influence of cat urine odour in suppressing development and fertility in Campbell's hamster males.
Exposure to this odour from postnatal day 11 until day 45 (sexual maturation) resulted in reduced sex organ weights, reduced
testosterone levels and in an increase in abnormalities of the synaptonemal complex in both sex chromosomes and autosomes.
Subsequent breeding experiments revealed a significant decrease in litter size. All these data indicate a severe effect of
predator odour on the breeding success of potential prey species. It is assumed that these effects are caused by the sulphurous
compounds in the urine; however, the underlying mechanisms are not yet known.
Received: 31 January 2000 / Accepted in revised form: 6 June 2000 相似文献
227.
The abundance patterns of ant communities were monitored with pitfall traps during 14 weeks in four northern California, dry farmed, apple orchards: an abandoned orchard undisturbed for 25 years, two ‘organically’ managed orchards, one with a cover crop of bell beans (Vicia faba) and grasses and the other kept clean of cover by discing, and a ‘commercial’ clean cultivated orchard sprayed with organophosphate insecticides. Six species of ants coexisted in the abandoned orchard, whereas only two species were found in the managed orchards. In both the organic and sprayed, clean cultivated systems, ants were more abundant in the orchard edges than in the vegetation-free centers. This trend was not apparent in the abandoned or organic cover orchards, where plant diversity in the center was similar to that of the edges. Ant predation on potato tuberworm larvae, Phthorimaea operculella, artificially placed on the orchard floor, declined with the intensity of management and vegetational simplication. A higher incidence of larval removal occurred in the edges than in the centers of the clean cultivated orchards. No noticeable populations of ants were detected on the trees in any of the orchards. Increased vegetational diversity and lack of disturbance appeared to affect ant locomotory activity and foraging efficiency by creating preferred sheltering and feeding sites. 相似文献
228.
229.
230.