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   18580篇
  免费   226篇
  国内免费   152篇
安全科学   598篇
废物处理   718篇
环保管理   2723篇
综合类   3385篇
基础理论   4633篇
环境理论   14篇
污染及防治   4566篇
评价与监测   1150篇
社会与环境   1030篇
灾害及防治   141篇
  2022年   151篇
  2021年   149篇
  2020年   127篇
  2019年   160篇
  2018年   258篇
  2017年   298篇
  2016年   404篇
  2015年   331篇
  2014年   446篇
  2013年   1573篇
  2012年   595篇
  2011年   792篇
  2010年   613篇
  2009年   679篇
  2008年   772篇
  2007年   830篇
  2006年   753篇
  2005年   598篇
  2004年   578篇
  2003年   598篇
  2002年   519篇
  2001年   602篇
  2000年   461篇
  1999年   289篇
  1998年   236篇
  1997年   230篇
  1996年   244篇
  1995年   254篇
  1994年   246篇
  1993年   232篇
  1992年   246篇
  1991年   227篇
  1990年   229篇
  1989年   191篇
  1988年   163篇
  1987年   150篇
  1986年   179篇
  1985年   171篇
  1984年   178篇
  1983年   185篇
  1982年   183篇
  1981年   184篇
  1980年   168篇
  1979年   161篇
  1978年   111篇
  1977年   130篇
  1974年   117篇
  1973年   92篇
  1972年   109篇
  1971年   97篇
排序方式: 共有10000条查询结果,搜索用时 250 毫秒
171.
172.
173.
Using chemical process simulation to design industrial ecosystems   总被引:2,自引:0,他引:2  
Chemical process simulation (CPS) software has been widely used by chemical (process) engineers to design, test, optimise, and integrate process plants. It is expected that industrial ecologists to bring these same problem-solving benefits to the design and operation of industrial ecosystems can use CPS. This paper provides industrial ecology researchers and practitioners with an introduction to CPS and an overview of chemical engineering design principles. The paper highlights recent research showing that CPS can be used to model industrial ecosystems, and discusses the benefits of using CPS to address some of the technical challenges facing companies participating in an industrial ecosystem. CPS can be used to (i) quantitatively evaluate and compare the potential environmental and financial benefits of material and energy linkages; (ii) solve general design, retrofit, or operational problems; (iii) help to identify complex and often counter-intuitive solutions; and (iv) evaluate what-if scenarios. CPS should be a useful addition to the industrial ecology toolbox.  相似文献   
174.
175.
176.
The female silkmoth Bombyx mori L. emits a second pheromone component bombykal (E-10, Z-12-hexade-cadien-1-al) in addition to the well-known sexual attractant bombykol (E-10, Z-12-hexadecadien-1-ol). Bombykal stimulates its own specialized and highly sensitive olfactory cells of the male moth. Surprisingly, the aldehyde inhibits the release of the male's wing-fluttering response to bombykol.  相似文献   
177.
178.
Herlitz junctional epidermolysis bullosa (HJEB) is a severe blistering disorder which usually results in death during infancy. We have previously shown that the anchoring filament protein laminin-5 (kalinin/nicein), which mediates keratinocyte attachment and dermal–epidermal cohesion, is abnormally expressed in individuals with HJEB. Laminin-5 was detected by Western blot analysis in amniotic fluid from 44 consecutive normal secondtrimester control pregnancies, but was undetectable in second-trimester amniotic fluid from four pregnancies with fetuses affected by HJEB. In one case of severe non-Herlitz JEB, laminin-5 was detected in both amniotic fluid and skin. In human amniotic fluid, the laminin-5 a3 subunit was processed to a major 165 kD species and a minor 145 kD species and the β2 subunit was partially processed to 105 kD. Although laminin-5 was covalently associated with laminin-6 (K-laminin) in amniotic membrane, no covalent interaction was detected in amniotic fluid. Laminin-5 from amniotic fluid strongly supported keratinocyte attachment. These results suggest that Western blot analysis of second-trimester amniotic fluid is useful in determining the prenatal diagnosis of HJEB and that laminin-5 may serve a physiologically important function in amniotic fluid.  相似文献   
179.
Five cases of mosaicism for an isochromosome of 20q have been detected from a total of 50 000 cases analysed for prenatal diagnosis by amniocentesis. Karyotypes were designated mos 46,X_/46,X_,i(20q). In all cases, the abnormal cell line was detected in more than one primary culture, thus fulfilling the criterion for true (level III) mosaicism. Indications for prenatal diagnosis were parental anxiety (two cases), low maternal serum alpha-fetoprotein (AFP) (two cases), and high maternal serum AFP (one case). Level II ultrasounds on all five fetuses were normal, and the abnormal cell line was never detected in fetal blood and/or cord blood. All five pregnancies were continued and had normal outcomes, with birth weights ranging from 2.4 to 3.8 kg. The development of all five children has been normal, with the oldest child in the study now 4 years of age. We suggest that the abnormal cell line in each case was of extrafetal origin, and that this may be one of the more common examples of this phenomenon, occurring in approximately 1/10000 prenatal diagnoses. Mosaicism i(20q) may have been missed in the past because of the higher resolution necessary to detect this subtle change.  相似文献   
180.
The attitudes of 190 patients who had undergone chorionic villus sampling (CVS) were assessed by means of a questionnaire. One hundred and fifty-two patients replied of whom 68 (45 per cent) were referred because of increased maternal age and in the other 84 cases the indications included previous chromosomal abnormalities, fetal sexing, DNA analysis, and biochemical analysis. One hundred and twenty-two patients had a transcervical procedure, 24 had a transabdominal, and six patients required both procedures. One hundred and forty-one patients (93 per cent) reported CVS to be a satisfactory procedure, and the same percentage thought earlier diagnosis was beneficial. Thirty-nine patients (81 per cent) reported a better experience with CVS than with a previous amniocentesis. A majority of patients (93 per cent) wished a CVS in a future pregnancy and 137 patients (97 per cent) would accept a risk of miscarriage from the procedure of twice that quoted for amniocentesis (1 per cent).  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