首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   17880篇
  免费   201篇
  国内免费   154篇
安全科学   478篇
废物处理   761篇
环保管理   2526篇
综合类   2683篇
基础理论   4822篇
环境理论   6篇
污染及防治   4586篇
评价与监测   1217篇
社会与环境   1043篇
灾害及防治   113篇
  2022年   149篇
  2021年   128篇
  2020年   123篇
  2019年   134篇
  2018年   229篇
  2017年   266篇
  2016年   377篇
  2015年   303篇
  2014年   488篇
  2013年   1503篇
  2012年   570篇
  2011年   792篇
  2010年   706篇
  2009年   646篇
  2008年   771篇
  2007年   810篇
  2006年   702篇
  2005年   607篇
  2004年   588篇
  2003年   601篇
  2002年   576篇
  2001年   684篇
  2000年   510篇
  1999年   280篇
  1998年   216篇
  1997年   238篇
  1996年   239篇
  1995年   267篇
  1994年   260篇
  1993年   201篇
  1992年   223篇
  1991年   204篇
  1990年   230篇
  1989年   211篇
  1988年   177篇
  1987年   184篇
  1986年   175篇
  1985年   178篇
  1984年   190篇
  1983年   174篇
  1982年   161篇
  1981年   156篇
  1980年   141篇
  1979年   164篇
  1978年   127篇
  1977年   135篇
  1976年   98篇
  1974年   98篇
  1973年   106篇
  1972年   91篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
541.
Twenty-two pesticides and metabolites selected on the basis of a regional priority list, were surveyed in surface river waters by high performance liquid chromatography coupled in tandem with UV diode array detection and mass spectrometry, after an off-line pre-concentration step. Pesticide concentrations ranged between 0.07 and 4.8 microg/l according to the compound and sampling period. Analytical results were linked to the environmental risk of pesticides, evaluated by their system investigation of risk by integration of score (SIRIS) rank.  相似文献   
542.
Accelerated remediation of pesticide-contaminated soil with zerovalent iron   总被引:3,自引:0,他引:3  
High pesticide concentrations in soil from spills or discharges can result in point-source contamination of ground and surface waters. Cost-effective technologies are needed for on-site treatment that meet clean-up goals and restore soil function. Remediation is particularly challenging when a mixture of pesticides is present. Zerovalent iron (Fe0) has been shown to promote reductive dechlorination and nitro group reduction of a wide range of contaminants in soil and water. We employed Fe0 for on-site treatment of soil containing > 1000 mg metolachlor, > 55 mg alachlor, > 64 mg atrazine, > 35 mg pendimethalin, and > 10 mg chlorpyrifos kg(-1). While concentrations were highly variable within the windrowed soil, treatment with 5% (w/w) Fe0 resulted in > 60% destruction of the five pesticides within 90 d and increased to > 90% when 2% (w/w) Al2(SO4)3 was added to the Fe0. GC/MS analysis confirmed dechlorination of metolachlor and alachlor during treatment. Our observations support the use of Fe0 for ex situ treatment of pesticide-contaminated soil.  相似文献   
543.
544.
Hydroxyprogesterone caproate is one of the most effective and widely used drugs for the treatment of uterine bleeding and threatened miscarriage in women. Hydroxyprogesterone caproate was administered to pregnant rats in order to assess the effect of intraperitoneal exposure to supranormal levels of hydroxyprogesterone caproate on the male reproductive potential in the first generation. The cauda epididymal sperm count and motility decreased significantly in rats exposed to hydroxyprogesterone caproate during embryonic development, when compared with control rats. The levels of serum testosterone decreased with an increase in follicle stimulating hormone and luteinizing hormone in adult rats exposed to hydroxyprogesterone caproate during the embryonic stage. It was suggested that the impairment of male reproductive performance could be mediated through the inhibition of testosterone production.  相似文献   
545.
546.
True structural chromosomal mosaicism are rare events in prenatal cytogenetics practice and may lead to diagnostic and prognostic problems. Here is described the case of a fetus carrying an abnormal chromosome 15 made of a whole chromosome 2p translocated on its short arm in 10% of the cells, in association with a normal cell line. The fetal karyotype was 46,XX,add(15)(p10).ish t(2;15)(p10;q10)(WCP2+)[3]/46,XX[27]. Pregnancy was terminated and fetus examination revealed a growth retardation associated with a dysmorphism including dolichocephaly, hypertelorism, high forehead, low-set ears with prominent anthelix and a small nose, which were characteristic of partial trisomy 2p. Possible aetiologies for prenatal mosaicism involving a chromosomal structural abnormality are discussed. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   
547.
548.
549.
Anticardiolipin antibodies were measured in 60 pregnant women with acute parvovirus B19 infection. Test results for eight (13.3 per cent) women were positive for anticardiolipin antibody. Six of these eight women became negative later, yielding a prevalence of anticardiolipin antibodies of 3.3 per cent (2/60) 6 months after acute parvovirus B19 infection. Anticardiolipin antibody positivity was not associated with an increased risk of abortion, fetal death, or maternal complications. This study suggests that there is an elevated frequency of anticardiolipin antibodies in pregnant women with acute parvovirus B19, probably representing an epiphenomenon. However, this is not associated with an adverse maternal or perinatal outcome.  相似文献   
550.
A prenatally detected case of a rare mosaic tetrasomy 12p/trisomy 12p is reported, presenting as the well-known accessory isochromosome 12p and a supernumerary single 12p marker in 17/24 and 6/24 clones of cultured amniotic fluid cells, respectively. The chromosomal nature of both marker chromosomes was investigated in cultured amniotic fluid cells by fluorescent in situ hybridization with various probes: the 12-centromeric probes pa12H8 and D12Z3, a whole chromosome 12 paint, and the chromosome 12p-specific paint M28. DNA analysis revealed a maternal origin of the extra 12p material. After counselling, the parents requested termination of pregnancy. Inspection and autopsy of the fetus revealed many of the dysmorphisms and internal structural abnormalities of the Pallister–Killian syndrome.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号