全文获取类型
收费全文 | 17938篇 |
免费 | 238篇 |
国内免费 | 158篇 |
专业分类
安全科学 | 546篇 |
废物处理 | 671篇 |
环保管理 | 2794篇 |
综合类 | 3210篇 |
基础理论 | 4412篇 |
环境理论 | 11篇 |
污染及防治 | 4432篇 |
评价与监测 | 1108篇 |
社会与环境 | 1008篇 |
灾害及防治 | 142篇 |
出版年
2022年 | 143篇 |
2021年 | 142篇 |
2020年 | 132篇 |
2019年 | 156篇 |
2018年 | 229篇 |
2017年 | 270篇 |
2016年 | 372篇 |
2015年 | 316篇 |
2014年 | 402篇 |
2013年 | 1586篇 |
2012年 | 541篇 |
2011年 | 716篇 |
2010年 | 585篇 |
2009年 | 625篇 |
2008年 | 727篇 |
2007年 | 752篇 |
2006年 | 721篇 |
2005年 | 581篇 |
2004年 | 543篇 |
2003年 | 577篇 |
2002年 | 506篇 |
2001年 | 566篇 |
2000年 | 456篇 |
1999年 | 268篇 |
1998年 | 234篇 |
1997年 | 218篇 |
1996年 | 237篇 |
1995年 | 241篇 |
1994年 | 229篇 |
1993年 | 225篇 |
1992年 | 239篇 |
1991年 | 227篇 |
1990年 | 221篇 |
1989年 | 192篇 |
1988年 | 176篇 |
1987年 | 149篇 |
1986年 | 178篇 |
1985年 | 182篇 |
1984年 | 198篇 |
1983年 | 192篇 |
1982年 | 190篇 |
1981年 | 194篇 |
1980年 | 172篇 |
1979年 | 183篇 |
1978年 | 132篇 |
1977年 | 142篇 |
1974年 | 117篇 |
1973年 | 99篇 |
1972年 | 110篇 |
1971年 | 99篇 |
排序方式: 共有10000条查询结果,搜索用时 370 毫秒
301.
302.
303.
304.
The “Linh Duong” (Pseudonovibos spiralis), a newly described Vietnamese bovid, has been shown to be related to the Caprinae on the basis of the mitochondrial cytochrome
b gene sequencing from horn fragments. To integrate the greatest available biodiversity we performed a new phylogenetic analysis
including all genera of Caprinae. Unexpectedly, Pseudonovibos is found to be robustly associated with Rupicapra, and closer to the Alpine than to the Pyrenean chamois. Several clues led us to interpret this result as a carry-over DNA
contamination of Pseudonovibos by Rupicapra.
Received: 19 July 1999 / Accepted in revised form: 20 October 1999 相似文献
305.
306.
Maternal serum CA 125 levels were determined at 9–11 menstrual weeks for 26 cases of trisomy 13 (n = 4), trisomy 18 (n = 7), trisomy 21 (n = 15), and appropriate controls. There were no statistically significant differences between groups. 相似文献
307.
H. Brandenburg MD W. De Koning M. G. J. Jahoda Th. Stijnen M. A. J. De Ridder E. S. Sachs J. W. Wladimiroff 《黑龙江环境通报》1992,12(12):1031-1035
One hundred and fifty-one women of advanced maternal age who underwent genetic termination of pregnancy (TOP) were studied for their reproductive behaviour and the type of procedure for prenatal diagnosis in a subsequent pregnancy. A total of 59 women (39 per cent) had a further pregnancy. In all continuing pregnancies prenatal diagnosis was performed, of which 75 per cent consisted of chorionic villus sampling (CVS). Reproductive behaviour following a genetic termination was negatively correlated with maternal age and parity. Both reproductive behaviour and the choice to undergo a diagnostic procedure in the next pregnancy were independent of the type of diagnostic procedure in the previous affected pregnancy. 相似文献
308.
309.
310.
Christine Willekes Frans J. M. E. Roumen MD PhD Anne-Marie W. van Elsacker-Niele Harro T. Weiland Christl Vermey-Keers Johan H. J. M. van Krieken Christine E. M. de Die-Smulders Guus J. H. Hamers Gerrie P. M. Vaes-Peters 《黑龙江环境通报》1994,14(3):181-185
In a case of hydrops fetalis, serological examination showed a recent maternal human parvovirus B19 infection. Amniocentesis revealed a unique unbalanced translocation between chromosomes 3 and 11 of the fetus. The mother proved to have a balanced reciprocal translocation between chromosomes 3 and 11. A grossly macerated hydropic male fetus was delivered with a flat nose and low implanted deformed ears. Histopathological examination revealed nuclear inclusion bodies in fetal erythroid cells, confirming human parvovirus B19 infection. Parvovirus B19 DNA was demonstrated by in situ hybridization in the nuclei of heart muscle cells. Our finding of two different disorders in one case illustrates the importance of a complete evaluation of every case of hydrops fetalis, especially concerning counselling on the outcome of future pregnancies. The human parvovirus B19 infection will not recur due to the acquired immunity of the mother, whereas the balanced reciprocal translocation will endanger future pregnancies. 相似文献