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   1792篇
  免费   17篇
  国内免费   23篇
安全科学   46篇
废物处理   62篇
环保管理   245篇
综合类   401篇
基础理论   347篇
环境理论   1篇
污染及防治   512篇
评价与监测   95篇
社会与环境   109篇
灾害及防治   14篇
  2023年   20篇
  2022年   18篇
  2021年   29篇
  2020年   21篇
  2019年   25篇
  2018年   47篇
  2017年   50篇
  2016年   60篇
  2015年   72篇
  2014年   77篇
  2013年   84篇
  2012年   80篇
  2011年   115篇
  2010年   97篇
  2009年   99篇
  2008年   90篇
  2007年   98篇
  2006年   80篇
  2005年   54篇
  2004年   80篇
  2003年   44篇
  2002年   62篇
  2001年   68篇
  2000年   30篇
  1999年   17篇
  1998年   17篇
  1997年   25篇
  1996年   19篇
  1995年   31篇
  1994年   19篇
  1993年   6篇
  1992年   14篇
  1991年   24篇
  1990年   11篇
  1989年   18篇
  1988年   7篇
  1987年   4篇
  1985年   5篇
  1984年   5篇
  1982年   10篇
  1981年   10篇
  1979年   9篇
  1970年   6篇
  1969年   4篇
  1966年   3篇
  1965年   4篇
  1962年   3篇
  1960年   4篇
  1959年   3篇
  1954年   3篇
排序方式: 共有1832条查询结果,搜索用时 18 毫秒
731.
The present paper summarises the results of the review and assessment of models developed for predicting the migration of radionuclides from catchments to water bodies. The models were classified and evaluated according to their main methodological approaches. A retrospective analysis of the principles underpinning the model development in relation to experimental finding and results was carried out. It was demonstrated that most of the various conceptual approaches of different modellers can be integrated in a general, harmonised perspective supported by a variety of experimental evidences. Shortcomings and advantages of the models were discussed.  相似文献   
732.
A simplistic aggregate model of global economic activity supports a 50-year visioning exercise with targets defined in terms of aggregate measures of global equity (convergence) and sustainability (contraction). Some ambitious combinations of these targets turn out to be infeasible even under the most favorable modeling assumptions. No contraction target (no reduction in fossil fuel consumption relative to the present) was possible, for example, if international capital transfers pushed per capita incomes in low-income countries above 33% of levels achieved in high-income countries. Lower prices for renewable alternatives to exhaustible resources generally made sustainability targets easier to achieve, but lower prices for renewable resources also made equity targets more difficult to achieve. Improved substitution between capital and labor made equity targets easier to achieve in relative terms, but improved substitution between capital and labor could make any given sustainability target more or less difficult to achieve. All the results suggest that it is possible to overstate the purported conflict between achieving sustainability and equity targets. The very transfers of international capital that would promote relative equity between high-income and low-income countries could also work to spread the incidence of achieving any sustainability target more evenly across their boundaries.Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.  相似文献   
733.
Environmental Science and Pollution Research - PM10 was collected during an EMEP winter campaign of 2017–2018 in two urban background sites in Barcelona (BCN) and Granada (GRA), two...  相似文献   
734.
Environmental Science and Pollution Research - This paper provides a novel survey of current collections of frozen raptor carcasses and tissue samples in natural history museums (NHMs),...  相似文献   
735.
736.
This study analyzed the isotopic profiles of four aragonitic shells of Scrobicularia plana in conjunction with measured seawater temperatures and salinities. Comparison of δ18OSHELL with expected values revealed fractionation of δ18O in near equilibrium with the ambient environment. Growth cessation occurred between November and March. Carbonate deposition stopped when temperatures were <12°C. Analysis of δ13CSHELL values suggested that carbon in the shell does not reflect the DIC in ambient water, likely due to the incorporation of metabolic carbon. An ontogenetic trend of increasing δ13C values over time was observed, likely related to changes in metabolic activity. Annual growth patterns were inferred from δ18OSHELL profiles and compared with internal and external growth lines. Estimations of age based on external lines were unreliable, resulting in overestimation of age and underestimation of growth rates, likely due to the disturbance lines being wrongly identified as annual. Analysis of internal lines may lead to over- or underestimation of age and was more reliable in recent portions of the shell.  相似文献   
737.
Recent evidence shows that the frequently proclaimed collapse of the traditional career model is actually not supported by job tenure data. This paper argues that the observed stability of job tenure might be explained by an increasing number of shamrock organizations. This organizational form has three types of workers: core employees, professional freelancers, and routine workers. In such an organization, two very different career models coexist. The organization largely determines the career of the core employee, whereas the individual essentially shapes that of the professional freelancer. This paper studies extensively the career of this second group: the professional freelancer, a growing phenomenon in many developed countries but not yet the focus of many career studies. We develop a freelance career success model on basis of the intelligent career framework augmented by insights from literature on entrepreneurship. Data are from a web survey with responses from about 1600 independent professionals in the Netherlands, in combination with 51 in‐depth interviews. We provide two main contributions. First, we report findings from the first large‐scale quantitative study into freelance career success. Second, this study enhances our understanding of the success of the modern career by building bridges between career and entrepreneurship literatures. We conclude that the external environment in which an individual freelancer operates is the most important factor determining career success. The study therefore suggests that more work needs to be performed on the relationship between the environment and individual career success. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
738.
Blast phenomena in urban tunnel systems   总被引:1,自引:0,他引:1  
Traffic infrastructure in urbanised areas is increasingly projected in tunnels underground or covered over, these days. A consequence is that in case of an incident with hazardous materials the safety level for fellow road users in tunnels is considerably less than it is in surface infrastructure. To reduce the consequences of incidents for fellow tunnel users, urban tunnels are sometimes interrupted by open spaces of limited length. Open spaces allow, for instance, the release of smoke in case of a fire. In this way, possible lethal effects are limited to the tunnel section in which the incident occurred. To what extent an open space may also be effective in the mitigation of blast effects from an explosion in a tunnel system is subject of this paper.

To this end, the blast effects originating from the rupture of a 50 m3 LPG pressure vessel in an urban tunnel system have been computed by numerical simulation. The results show that an open space in a tunnel system has a significant mitigating effect on the blast effects indeed. However, as a consequence of the ingress of a high-velocity jet flow that follows on a primary blast wave, a second blast wave develops in the tunnel section following on an open space. The strength of this second blast wave is not very dependent on the length of the open space. It shows that an open space in a tunnel system may not always limit the lethal effects of explosion incidents in tunnels to the tube in which the incident occurred. The second blast wave in the tunnel section following on an open space may have lethal consequences for fellow tunnel users by car window failure.  相似文献   

739.
The current paper investigated the longitudinal effects of mass career customization (MCC) on job attitudes and objective career outcomes of employees in a professional service firm in the Netherlands. On the basis of theory on individualization of career trajectories, it was expected that the possibility for employees to customize their careers would be positively related to their job attitudes and subsequent objective career success, as indicated by their levels of affective commitment, work engagement, and received salary and bonuses. However, these effects were expected to occur primarily under the combination of high manager support for implementation of career customization and, on the basis of lifespan theory, older workers, as customization fulfills their increased heterogeneous career preferences. A three‐wave longitudinal study largely showed support for the study hypotheses; the relation between MCC use and work engagement and subsequent career success was stronger for older workers who received support for MCC, whereas the relation between MCC use and commitment was negative for older workers who received low support. The study shows the benefits of career customization in organizations by showing the conditions under which these benefits will manifest. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
740.
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