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   204篇
  免费   0篇
  国内免费   1篇
安全科学   9篇
废物处理   7篇
环保管理   11篇
综合类   13篇
基础理论   27篇
污染及防治   106篇
评价与监测   5篇
社会与环境   26篇
灾害及防治   1篇
  2022年   4篇
  2021年   1篇
  2019年   4篇
  2018年   1篇
  2017年   3篇
  2016年   5篇
  2015年   14篇
  2014年   7篇
  2013年   13篇
  2012年   11篇
  2011年   8篇
  2010年   5篇
  2009年   8篇
  2008年   11篇
  2007年   9篇
  2006年   15篇
  2005年   13篇
  2004年   7篇
  2003年   4篇
  2002年   2篇
  2001年   7篇
  2000年   2篇
  1999年   2篇
  1998年   4篇
  1997年   4篇
  1996年   3篇
  1995年   2篇
  1994年   2篇
  1993年   1篇
  1992年   2篇
  1990年   1篇
  1989年   3篇
  1988年   1篇
  1985年   1篇
  1984年   1篇
  1983年   3篇
  1982年   3篇
  1981年   6篇
  1980年   1篇
  1979年   2篇
  1977年   5篇
  1976年   3篇
  1956年   1篇
排序方式: 共有205条查询结果,搜索用时 46 毫秒
141.
Life-history theory predicts that individuals should increase their reproductive effort when the fitness return from reproduction is high. Females mated with high-quality males are therefore expected to have higher investment than females mated with low-quality males, which could bias estimates of paternal effects. Investigating the traits females use in their allocation decisions and the aspects of reproduction that are altered is essential for understanding how sexual selection is affected. We studied the potential for differential female allocation in a captive population of a precocial bird, the Chinese quail, Coturnix chinensis. Females paired with males with large sexual ornaments laid larger, but not more, eggs than females paired with males with small sexual ornaments. Furthermore, female egg mass was also significantly positively affected by male testis size, probably via some unknown effect of testis size on male phenotype. Testis size and ornament size were not correlated. Thus, both primary and secondary male sexual traits could be important components of female allocation decisions. Experimental manipulation of hormone levels during embryonic development showed that both male and female traits influencing female egg size were sensitive to early hormone exposure. Differences in prenatal hormone exposure as a result of maternal steroid allocation to eggs may explain some of the variation in reproductive success among individuals, with important implications for non-genetic transgenerational effects in sexual selection.Communicated by C. Brown  相似文献   
142.
143.
Inter-annual variability of surface ozone (O3) and nitrogen dioxide (NO2) over Europe has been studied over the period 1958–2003 using a three-dimensional Chemistry-Transport Model coupled to meteorological data from the ERA40 data set produced at the European Centre of Medium-range Weather Forecasts (ECMWF). Emissions and boundary conditions were kept at present levels throughout the simulation period. It was found that the annual mean NO2 concentration varies between ±50% and the summer mean O3 concentration varies between −10 and +20 percent (%) compared to the 46-year average over the model domain. There is also variation in ozone and NO2 over longer time scales. The last 22 years display high concentrations of ozone in central and south-western Europe and low concentrations in north-eastern Europe. The first 22 years display very high concentrations of NO2 over the North Sea. There is indication of trends in ozone and nitrogen dioxide but this has to be investigated further. Such information is one factor that should be taken into account when considering future control strategies.  相似文献   
144.
A scenario-based experiment was employed to test seven hypotheses concerning several causes and consequences of cynicism in the workplace. The results of a 2×2×2 MANOVA revealed that high levels of executive compensation, poor organizational performance, and harsh, immediate layoffs generate cynicism in white-collar workers. Furthermore, regression analyses showed that cynicism relates negatively to intentions to perform organizational citizenship behaviors and intentions to comply with requests to engage in unethical behaviors. The study provides a first experimental investigation of an important employee attitude and indicates directions for further research. © 1997 John Wiley & Sons, Ltd.  相似文献   
145.
This study is concerned with the longitudinal representation of injury risk obtained using alternative injury-rate denominators—hours worked and production volume. It investigates injury risks at the underground extraction phase in a Swedish iron-ore mine. Six stages of mining development are defined, and three risk measures are employed: average injury rates (AIRs) by stage, injury rate ratios (IRRs) by stage, and annual injury rates (AnIRs). The two denominators give a quite different representation of injury risk at the early stages of the development of the mine, but tend increasingly to provide a similar picture (similar ratios) at later stages. It is concluded that automated production processes, as opposed to mechanized ones, tend to make hours worked and production volume interchangeable denominators. Choice of appropriate denominator may depend upon whether the individual or the production process is in focus.  相似文献   
146.
This paper systematically reviews the literature on how to reduce nutrient emissions to the Baltic Sea cost-effectively and considerations for allocating these costs fairly among countries. The literature shows conclusively that the reduction targets of the Baltic Sea Action Plan (BSAP) could be achieved at considerably lower cost, if countries would cooperate to implement the least costly abatement plan. Focusing on phosphorus abatement could be prudent as the often recommended measures—wastewater treatment and wetlands—abate nitrogen too. An implication of our review is that the potential for restoring the Baltic Sea to good health is undermined by an abatement strategy that is more costly than necessary and likely to be perceived as unfair by several countries. Neither the BSAP nor the cost-effective solution meet the surveyed criteria for fairness, implying a need for side-payments.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01580-4.  相似文献   
147.
Atmospheric mercury at mediterranean coastal stations   总被引:2,自引:0,他引:2  
Mercury in air has been measured at five coastal Mediterranean sites, involving measurements in Spain, France, Italy, Slovenia and Israel. Four two-weeks long measurements campaigns were performed at the five sites. The measurements were carried out during autumn 2003 and winter, spring and summer 2004. Total gaseous mercury/elemental gaseous mercury, particulate mercury and divalent gaseous mercury were measured in parallel at the five sites. The activities constituted a subtask of the EU funded MERCYMS research project, which also included Mediterranean Sea cruises where both mercury in air and water were measured. The result from an evaluation of all the coastal air data is presented. Mercury concentrations from the different sites are compared with similar data obtained in northern Europe and elsewhere. The result shows that the background concentration of mercury in Mediterranean coastal air is lower than earlier anticipated. Background concentrations of TGM, RGM and TPM corresponded to 1.75–1.80 ng m−3, 1–13 and 3–23 pg m−3, respectively. The measurements also showed that the mercury concentration occasionally can be very high in some areas due to local anthropogenic emissions. It is proposed that diurnal variation in RGM concentrations observed during situation with nocturnal inversion merely is an effect of meteorology rather than due to local photochemistry.  相似文献   
148.
Due to the high-temperature boiler corrosion induced by chloride-rich fly ash deposits, steam generation in today’s Waste-to-Energy (WtE) plants is typically designed only for 40 bar/400 °C as an economic compromise between acceptable corrosion rate and maximum power generation. The high-corrosive metal chlorides in the fly ash can react with SO2 forming low-corrosive sulfates. The sulfation efficiency is enhanced by high SO2 levels and sufficient residence time of the flue gas at high-temperatures (700–900 °C). The fly ash sulfation was tested in full scale in a Swedish WtE plant by applying the economic sulfur recirculation method. Probes of several alloys (16Mo3, Inconel 625, Sanicro 28) were exposed for 1000 h at controlled material temperatures in the superheater position, at normal and during sulfating operation respectively. Analyses of the fly ash showed that the molar Cl/S was decreased to values well below 1 and the corresponding corrosion rates of the individual material samples were less than half when sulfur recirculation was in operation. These positive findings demonstrate that the sulfur recirculation process has high potential for low-corrosive high-temperature steam generation (T ≈ 500 °C) and improved electricity production. Further steam superheating can be realized by staged superheating using small amounts of secondary fuel.  相似文献   
149.
Within-city green infrastructure can offer opportunities and new contexts for people to become stewards of ecosystem services. We analyze cities as social–ecological systems, synthesize the literature, and provide examples from more than 15 years of research in the Stockholm urban region, Sweden. The social–ecological approach spans from investigating ecosystem properties to the social frameworks and personal values that drive and shape human interactions with nature. Key findings demonstrate that urban ecosystem services are generated by social–ecological systems and that local stewards are critically important. However, land-use planning and management seldom account for their role in the generation of urban ecosystem services. While the small scale patchwork of land uses in cities stimulates intense interactions across borders much focus is still on individual patches. The results highlight the importance and complexity of stewardship of urban biodiversity and ecosystem services and of the planning and governance of urban green infrastructure.  相似文献   
150.
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