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   324篇
  免费   9篇
  国内免费   3篇
安全科学   9篇
废物处理   12篇
环保管理   56篇
综合类   68篇
基础理论   71篇
环境理论   1篇
污染及防治   90篇
评价与监测   13篇
社会与环境   11篇
灾害及防治   5篇
  2023年   4篇
  2022年   5篇
  2021年   7篇
  2020年   7篇
  2019年   7篇
  2018年   3篇
  2017年   8篇
  2016年   14篇
  2015年   10篇
  2014年   11篇
  2013年   32篇
  2012年   12篇
  2011年   26篇
  2010年   30篇
  2009年   12篇
  2008年   17篇
  2007年   14篇
  2006年   8篇
  2005年   7篇
  2004年   12篇
  2003年   9篇
  2002年   5篇
  2001年   7篇
  2000年   3篇
  1999年   2篇
  1998年   3篇
  1997年   3篇
  1996年   3篇
  1995年   6篇
  1994年   6篇
  1993年   3篇
  1992年   5篇
  1990年   3篇
  1989年   2篇
  1986年   4篇
  1985年   4篇
  1984年   2篇
  1982年   1篇
  1981年   1篇
  1980年   3篇
  1978年   3篇
  1977年   1篇
  1973年   1篇
  1970年   1篇
  1969年   1篇
  1968年   1篇
  1964年   1篇
  1963年   1篇
  1957年   1篇
  1928年   1篇
排序方式: 共有336条查询结果,搜索用时 15 毫秒
1.
A case of gastric outlet obstruction diagnosed prenatally at 22 weeks' gestation is described. The differential diagnosis and the clinical management of this rare condition are discussed, and an updated literature review is presented.  相似文献   
2.
3.
日本企业的环境责任   总被引:3,自引:0,他引:3  
上世纪90年代初期,日本的许多企业都未将环境管理、指标、社会责任等纳入企业成本、运营和规划中,他们认为这会给企业带来负担。也无必要,这种情形与现阶段的中国企业有着非常类似的“价值取向”,我们希望这篇文章能给中国的同行们带来一些思考和借鉴,从而使得我们的企业更绿,环境更清洁,社会更可持续。[编者按]  相似文献   
4.
In order to promote the next generation of atmospheric scientists, the task Training and Education (T&E) in ACCENT, the European Network of Excellence in Atmospheric Composition Change (www.accent-network.org) has developed and implemented an Integrated Learning Environment (ILE). For school teachers and their students, the Internet-based “Global Change Magazine” provides up-to-date and freely accessible scientific material in English and five other languages. Additionally, T&E has produced online teaching material for early-career scientists. These e-learning modules are now being used in University Master's courses across Europe. T&E also organised training events for early-career scientists, combining scientific content with development in transferable skills, to focus on interdisciplinary collaboration, interaction with senior scientists, communication with stakeholders, and dissemination to the general public. Evaluation based on participant feedback evidences the effectiveness of these events, e.g., in terms of motivation to remain in the field. Methodologies and materials from T&E are being published in a Handbook on Best Practice, intended for both educators and scientists around the globe who are involved in education in the field of air quality and climate change science.  相似文献   
5.
OBJECTIVE: To evaluate the effectiveness of the WalkSafe program, an elementary school-based pedestrian safety program in a single high-risk district in Miami-Dade County. METHODS: Sixteen elementary schools were identified in a single high-risk district and enrolled in a one-year study. All schools implemented the WalkSafe program on the last week of January 2003. A pre, post, and three-month post testing of pedestrian safety knowledge was conducted. An observational component was also implemented at four schools that were randomly chosen. Engineering recommendations and law enforcement initiatives were also performed. RESULTS: A total of 6467 children from K-5th grade from 16 elementary schools participated in the program. Of these 5762 tests were collected over three different testing times. A significant difference (p-value < 0.001) was found between the pre and post testing conditions across all grade levels. There was no significant difference found between the post and three-month post testing conditions across all grade levels (p-value > 0.05). The observational data collected at four schools across the different testing times demonstrated a significant difference found between pre and post testing conditions for Group A (stop at the curb and look left, right, left) and also for Group B (midstreet crossing and darting out) (p-value < 0.05). There was no difference found between comparing the pre-test or post-test condition with the three-month post-test time. There were many environmental modifications that were recommended and actually performed. CONCLUSION: The WalkSafe program implemented in a single high-risk district was shown to improve the pedestrian safety knowledge of elementary school children. The observational data demonstrated improved crossing behaviors from pre-test to post-testing conditions. Future research will focus on sustaining the program in this district and expanding the program throughout our county.  相似文献   
6.
A myriad of factors, both economic and political, influenced the voting by members of the United States Congress on the 1978 National Energy Act. Determinant factors considered in our analysis included the percentage of residents in the Congressman's district residing in the central city or on farms; the percentage of residents who belong to labor unions; the average level of education of the residents; oil, coal, and natural gas production in the state relative to total domestic production. The results, determined by means of logit analysis, indicate that the impact on low-income energy consumers, the effect on overall employment, the impact on farmers, and the benefits to energy interests, as well as ideology and the subjective perception that the need exists to do something about the energy situation in the United States, were all important explanatory factors.The author is an economist with the United States Department of Energy. The views expressed are those of the author and do not necessarily represent the policies of the Department of Energy or the views of other Department of Energy staff members.  相似文献   
7.
A spatial and temporal equilibrium model of production, consumption, prices, and transmission is constructed to determine the efficient pricing and allocation of electrical energy in the United States. Regional coordination is technically feasible and economically attractive. It also maximizes environmental efficiencies. The duplication of electrical generation and transmission facilities yields a misallocation of resources.The utilities put forth specific arguments against coordinated operations. Yet in a fully integrated power system, each region would be expected to maximize the benefits of time diversity by purchasing from outside the region in lieu of the expansion of regional capacity. The Federal Energy Regulatory Commission has not yet made a serious move to encourage regional coordination and planning, but the Commission has the authority to promote such operations if it chooses to do so.The author is an economist with the Department of Energy. The views expressed are those of the author and do not necessarily represent the policies of the Department of Energy or the views of other staff members.  相似文献   
8.
There is an urgent need to develop sound theory and practice for biodiversity offsets to provide a better basis for offset multipliers, to improve accounting for time delays in offset repayments, and to develop a common framework for evaluating in-kind and out-of-kind offsets. Here, we apply concepts and measures from systematic conservation planning and financial accounting to provide a basis for determining equity across type (of biodiversity), space, and time. We introduce net present biodiversity value (NPBV) as a theoretical and practical measure for defining the offset required to achieve no-net-loss. For evaluating equity in type and space we use measures of biodiversity value from systematic conservation planning. Time discount rates are used to address risk of non-repayment, and loss of utility. We illustrate these concepts and measures with two examples of biodiversity impact–offset transactions. Considerable further work is required to understand the characteristics of these approaches.  相似文献   
9.
10.
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