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   427篇
  免费   10篇
  国内免费   1篇
安全科学   35篇
废物处理   12篇
环保管理   117篇
综合类   38篇
基础理论   105篇
污染及防治   100篇
评价与监测   19篇
社会与环境   11篇
灾害及防治   1篇
  2022年   3篇
  2021年   6篇
  2020年   4篇
  2019年   7篇
  2018年   10篇
  2017年   6篇
  2016年   10篇
  2015年   7篇
  2014年   10篇
  2013年   50篇
  2012年   20篇
  2011年   15篇
  2010年   13篇
  2009年   13篇
  2008年   19篇
  2007年   14篇
  2006年   21篇
  2005年   16篇
  2004年   14篇
  2003年   23篇
  2002年   16篇
  2001年   9篇
  2000年   4篇
  1999年   3篇
  1998年   8篇
  1997年   11篇
  1996年   9篇
  1995年   4篇
  1994年   6篇
  1993年   6篇
  1992年   10篇
  1991年   3篇
  1990年   4篇
  1989年   3篇
  1988年   10篇
  1987年   9篇
  1986年   4篇
  1984年   8篇
  1983年   5篇
  1982年   5篇
  1981年   1篇
  1980年   1篇
  1979年   1篇
  1978年   2篇
  1977年   2篇
  1975年   2篇
  1974年   1篇
  1973年   2篇
  1972年   2篇
  1970年   4篇
排序方式: 共有438条查询结果,搜索用时 578 毫秒
271.
Acidifying oceans are predicted to fundamentally alter marine ecosystems. Over the next century, acute studies suggest that the impacts of climate change on marine organisms and ecosystems may be catastrophic. To date, however, little is known about whether the response of marine organisms varies within a species and whether this provides a potential ??adaptive capacity??. Here, we show that selectively bred lines of the ecologically and economically important estuarine mollusc, the Sydney rock oyster Saccostrea glomerata, are more resilient to ocean acidification than the wild populations. When reared at elevated pCO2, we found a 25% reduction in shell growth of the selectively bred population of the Sydney rock oyster, Saccostrea glomerata, compared to a 64% reduction in shell growth of wild populations. This study shows that there are significantly different sensitivities to ocean acidification even within the same species, providing preliminary evidence that selective breeding may be a solution for important aquaculture industries to overcome the future effects of ocean acidification.  相似文献   
272.
273.
274.
275.
276.
277.
Private, voluntary eco-labelling and certification programmes are being developed for a number of industries to promote and verify higher environmental, economic and social standards. In some cases, these initiatives have developed regardless of whether there is initial, broad support within industry. This article seeks to identify some of the challenges inherent in the implementation of a sustainable development certification programme for the minerals and metals industry. The article looks for guidance from initiatives that are drawn for the most part from other resource industries, most notably forestry. While the article takes a Canadian perspective, many of the challenges raised in the article are also applicable internationally. The article concludes that stakeholders can learn from other resource industries if a decision is made to develop a certification programme for the minerals and metals industry. Crucial to the long-term success of such a programme will be the establishment of a true partnership among stakeholders throughout the initiative's development. Crown Copyright.  相似文献   
278.
Reproductive carrier screening started in some countries in the 1970s for hemoglobinopathies and Tay-Sachs disease. Cystic fibrosis carrier screening became possible in the late 1980s and with technical advances, screening of an ever increasing number of genes has become possible. The goal of carrier screening is to inform people about their risk of having children with autosomal recessive and X-linked recessive disorders, to allow for informed decision making about reproductive options. The consequence may be a decrease in the birth prevalence of these conditions, which has occurred in several countries for some conditions. Different programs target different groups (high school, premarital, couples before conception, couples attending fertility clinics, and pregnant women) as does the governance structure (public health initiative and user pays). Ancestry-based offers of screening are being replaced by expanded carrier screening panels with multiple genes that is independent of ancestry. This review describes screening in Australia, Cyprus, Israel, Italy, Malaysia, the Netherlands, Saudi Arabia, the United Kingdom, and the United States. It provides an insight into the enormous variability in how reproductive carrier screening is offered across the globe. This largely relates to geographical variation in carrier frequencies of genetic conditions and local health care, financial, cultural, and religious factors.  相似文献   
279.
Published studies have shown that some serum markers used in screening for Down syndrome tend to be lower among women with insulin-dependent diabetes mellitus (IDDM). On this basis, many screening programmes adjust the marker levels to take account of this difference. Recent studies suggested that the marker levels were not different, and so adjustment may no longer be needed, possibly because of better diabetic control. Data from a prenatal screening programme for Down syndrome were examined to see whether the median values of second-trimester screening markers were still reduced in pregnant women with IDDM. A total of 366 women with IDDM singleton pregnancies without Down syndrome were identified from the screening programme at Barts from 1989 to 2002. After allowing for maternal weight, the median multiples of the median (MoM) for IDDM-unaffected singleton pregnancies were as follows: 0.88 (95% confidence interval 0.84–0.93) for alphafetoprotein (AFP), 0.95 (0.91–0.99) for unconjugated oestriol (uE3), 0.90 (0.80–1.01) for total human chorionic gonadotrophin (total hCG), 0.98 (0.88–1.08) for free β-hCG, and 0.99 (0.89–1.10) for inhibin-A. The median levels for AFP and uE3 were statistically significantly lower in pregnant women with IDDM. The other markers were not significantly different in women with and without IDDM. There remains a case for adjusting AFP and uE3 levels in women with IDDM in prenatal screening programmes for Down syndrome. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   
280.
At many sites, long‐term monitoring (LTM) programs include metals as chemicals of concern, although they may not be site‐related contaminants and their detected concentrations may be natural. At other sites, active remediation of organic contaminants in groundwater results in changes to local geochemical conditions that affect metal concentrations. Metals should be carefully considered at both types of sites, even if they are not primary contaminants of concern. Geochemical evaluation can be performed at LTM sites to determine if the monitored metals reflect naturally high background and, hence, can be removed from the analytical program. Geochemical evaluation can also be performed pre‐ and post‐treatment at active remediation sites to document the effects of organics remediation on metals and identify the processes controlling metal concentrations. Examples from both types of sites are presented in this article. © 2008 Wiley Periodicals, Inc.  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