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   1674篇
  免费   4篇
  国内免费   8篇
安全科学   37篇
废物处理   38篇
环保管理   161篇
综合类   904篇
基础理论   153篇
污染及防治   281篇
评价与监测   67篇
社会与环境   39篇
灾害及防治   6篇
  2023年   9篇
  2022年   24篇
  2021年   18篇
  2020年   13篇
  2019年   7篇
  2018年   19篇
  2017年   25篇
  2016年   33篇
  2015年   27篇
  2014年   46篇
  2013年   114篇
  2012年   52篇
  2011年   55篇
  2010年   35篇
  2009年   37篇
  2008年   58篇
  2007年   38篇
  2006年   35篇
  2005年   40篇
  2004年   23篇
  2003年   35篇
  2002年   21篇
  2001年   7篇
  1998年   15篇
  1997年   7篇
  1995年   57篇
  1994年   56篇
  1993年   40篇
  1992年   34篇
  1991年   27篇
  1990年   34篇
  1989年   26篇
  1988年   36篇
  1987年   29篇
  1986年   23篇
  1985年   14篇
  1984年   12篇
  1983年   14篇
  1982年   11篇
  1979年   5篇
  1976年   6篇
  1975年   9篇
  1973年   10篇
  1919年   47篇
  1918年   44篇
  1917年   36篇
  1916年   53篇
  1915年   37篇
  1914年   71篇
  1913年   106篇
排序方式: 共有1686条查询结果,搜索用时 31 毫秒
101.
Corporate social responsibility (CSR) is increasingly required not only of private sector companies, but also of state-owned enterprises (SOEs), whose main function is to provide services to society and not principally to obtain financial reward. The important role played by managers in implementing CSR has been demonstrated by prior research. The objective of this paper is to examine how managers of SOEs perceive the concept of CSR, the reasons for their involvement and how it is integrated into everyday business practices. In addition, we examine whether managers' attitudes towards CSR policies are influenced by their personal profiles and by the sector in which the SOEs work. We find that, although these managers are aware of the importance of the CSR principles underlying their activities and understand the meaning, scope and dimensions of CSR, there remains an evident need to enhance the application of CSR policies among the strategies of SOEs. The manager profile and the sector in which the SOEs work both have a strong influence on their behaviour regarding CSR issues.  相似文献   
102.
The aim of the research was to evaluate, at site scale, the influence of freezing and freeze/thaw cycles on the survival of faecal coliforms and faecal enterococci in soil, in a climate change perspective. Before the winter period and during grazing, viable cells of faecal coliforms and faecal enterococci were detected only in the first 10 cm below ground, while,after the winter period and before the new seasonal grazing, a lower number of viable cells of both faecal indicators was detected only in some of the investigated soil profiles, and within the first 5 cm. Taking into consideration the results of specific investigations, we hypothesise that the non-uniform spatial distribution of grass roots within the studied soil can play an important role in influencing this phenomenon, while several abiotic factors do not play any significant role. Taking into account the local trend in the increase of air temperature, a different distribution of microbial pollution over time is expected in spring waters, in future climate scenarios. The progressive increase in air temperature will cause a progressive decrease in freeze/thaw cycles at higher altitudes, minimising cold shocks on microbial cells, and causing spring water pollution also during winter.  相似文献   
103.
104.
105.
106.
107.
108.
Amniocentesis was performed in view of a paternal balanced chromosomal rearrangement t(4;20)(p16;p12), inv(18)(p11q11). The pregnancy was complicated by severe oligohydramnios. The fetal karyotype was unbalanced: 46XX, der(4), t(4;20)(p16;p12), inv(18) (p11q11)pat., thus resulting in partial trisomy 2Op and monosomy 4p. In addition, the amniotic fluid alpha-fetoprotein (AFP) became increasingly elevated with gestational age. The pregnancy was terminated at 25 weeks. The fetus presented with typical facial dysmorphic features, unilateral cleft lip and palate, severe renal hypoplasia, consistent with the 4p- (Wolf-Hirschhorn) syndrome.  相似文献   
109.
110.
Using the polymerase chain reaction (PCR), it was possible to amplify a single copy fragment of the β-globin gene from 2–32 human embryonic cells obtained from arrested preimplantation embryos. For the detection of β-thalassaemia mutations, allele specific priming of the PCR using nested primers was employed using approximately 10 pg of DN A from individuals known to carry these mutations. This approach was successful in detecting the presence or absence of five Asian Indian β-thalassaemia mutations that were selected for this study. In spite of meticulous precautions against contamination, false-positive amplification was observed, a problem that will have to be overcome before this approach can be used in clinical practice.  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