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   539篇
  免费   21篇
  国内免费   3篇
安全科学   32篇
废物处理   48篇
环保管理   85篇
综合类   87篇
基础理论   112篇
环境理论   1篇
污染及防治   131篇
评价与监测   26篇
社会与环境   27篇
灾害及防治   14篇
  2023年   4篇
  2022年   10篇
  2021年   9篇
  2020年   9篇
  2019年   12篇
  2018年   18篇
  2017年   20篇
  2016年   21篇
  2015年   20篇
  2014年   22篇
  2013年   48篇
  2012年   29篇
  2011年   42篇
  2010年   22篇
  2009年   21篇
  2008年   23篇
  2007年   28篇
  2006年   32篇
  2005年   23篇
  2004年   14篇
  2003年   17篇
  2002年   18篇
  2001年   12篇
  2000年   3篇
  1999年   4篇
  1998年   1篇
  1997年   8篇
  1996年   8篇
  1995年   10篇
  1994年   15篇
  1993年   8篇
  1992年   6篇
  1991年   9篇
  1990年   1篇
  1989年   1篇
  1988年   3篇
  1987年   1篇
  1986年   2篇
  1985年   1篇
  1984年   1篇
  1983年   2篇
  1980年   1篇
  1977年   1篇
  1973年   1篇
  1968年   1篇
  1956年   1篇
排序方式: 共有563条查询结果,搜索用时 0 毫秒
91.
Analyses of the pattern of associations, social interactions, coalitions, and aggression among chacma baboons (Papio hamadryas ursinus) in the Okavango Delta of Botswana over a 16-year period indicate that adult females form close, equitable, supportive, and enduring social relationships. They show strong and stable preferences for close kin, particularly their own mothers and daughters. Females also form strong attachments to unrelated females who are close to their own age and who are likely to be paternal half-sisters. Although absolute rates of aggression among kin are as high as rates of aggression among nonkin, females are more tolerant of close relatives than they are of others with whom they have comparable amounts of contact. These findings complement previous work which indicates that the strength of social bonds enhances the fitness of females in this population and support findings about the structure and function of social bonds in other primate groups.  相似文献   
92.
The extractability of Cd, Pb, and Zn was investigated in contaminated agricultural topsoils located in an area highly affected by the past atmospheric emissions of two smelters in northern France in order to assess their mobility and human bioaccessibility. The determination of Cd, Pb, and Zn bioaccessibility (Unified Barge Method, in vitro test) was made to evaluate the absolute trace element (TE) bioavailability. The results highlighted differences in bioaccessibility between Cd, Pb, and Zn (Cd > Pb > Zn). The mean values of the bioaccessible fractions of Cd, Pb, and Zn during the gastric phase were 82, 55, and 33%, respectively, of the pseudototal concentrations, whereas during the gastrointestinal phase, the bioaccessible fractions of metals decreased to 45, 20, and 10%, respectively. Stepwise multiple regression analysis showed that human bioaccessibility was affected by various physicochemical parameters (i.e., sand, carbonates, organic matter, assimilated P, free Al oxides, and pseudototal Fe contents). Sequential extractions were performed as an indication of the TE availability in these soils. Cadmium occurred in the more available fractions, Pb was mostly present as bound by oxides, and a significant contribution to the pseudototal Zn concentration was defined as the unavailable residual form related to the crystalline structures of minerals. The concepts of bioavailability and bioaccessibility are important for quantifying the risks associated with exposure to environmental pollutants and providing more realistic information for human health.  相似文献   
93.

Oil contamination has become a primary environmental concern due to increased exploration, production, and use. When oil enters the soil, it may attach or adsorb to soil particles and stay in the soil for an extended period, contaminating the soil and surrounding areas. Nanoparticles have been widely used for the treatment of organic pollutants in the soil. Surfactant foam has effectively been employed to remediate various soil contaminants or recover oil compounds. In this research, a mixture of biosurfactant foam/nanoparticle was utilized for remediation of oil-contaminated soil. The results demonstrated that the biosurfactant/nanoparticle mixture and nitrogen gas formed high-quality and stable foams. The foam stability depended on the foam quality, biosurfactant concentration, and nanoparticle dosage. The pressure gradient change in the soil column relied on the flowrate (N2 gas + surfactant/nanoparticle mixture), foam quality, and biosurfactant concentration. The optimal conditions to obtain good quality and stable foams and high oil removal efficiency involved 1 vol% rhamnolipid, 1 wt% nanoparticle, and 1 mL/min flowrate. Biosurfactant foam/nanoparticle mixture was effectively used to remediate oil-contaminated soil, whereas the highest treatment efficiency was 67%, 59%, and 52% for rhamnolipid biosurfactant foam/nanoparticle, rhamnolipid biosurfactant/nanoparticle, and only rhamnolipid biosurfactant, respectively. The oil removal productivity decreased with the increase of flowrate due to the shorter contact time between the foam mixture and oil droplets. The breakthrough curves of oil pollutants in the soil column also suggested that the foam mixture’s maximum oil treatment efficiency was higher than biosurfactant/nanoparticle suspension and only biosurfactant.

  相似文献   
94.
This text describes two different experiences of co-operation between unionists and researchers that resulted in writing of a book. We emphasize their similarities and differences and discuss the importance of these experiences in the dynamics of research and training in Ergonomics.  相似文献   
95.
This paper examined the effects of work and family stressors and conflicts on Air Force women's mental health and functioning. We analyzed data from a 1993 survey of representative stratified samples of 525 Air Force women from the active duty reserve and guard forces. The analyses of the data are guided by the comprehensive model of work–family conflict that has been tested by Frone, Russell, and Cooper (1992) using a large representative community sample. Structural equation modeling analyses provided support for the work–family conflict model. The analyses also provided support for an extension of the model, which included the separate effects of marital and parental roles on mental health. The extended model demonstrated that job and parental stresses had direct effects on work–family conflicts and that job and marital distress and family–work conflict had an independent adverse effect on mental health. Whereas job and parental involvement had a beneficial effect on distress, they had an adverse effect on work–family conflicts. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   
96.
This paper is part of a two-year study to investigate the feasibility of initiating a Clean Development Mechanism (CDM) project in an indigenous community of Eastern Panamá, Ipetí-Emberá. We use participatory mapping and matrices as well as household surveys to develop a land-use/land-cover baseline scenario and examine the role of local participation in assessing land-use change. In Ipetí, land-use change has not occurred in a linear way over the last decades, and our data unveils socio-economic factors as potential key drivers of change. The concordance that we observed between geographic information and individual and collective perceptions of land-use change substantiates the possibility of using local knowledge in the establishment of baseline data for CDM projects. Our calculations suggest that the total carbon (C) stocks in the Tierra Colectiva (TC) of Ipetí-Emberá in 2004 represents a 47% reduction from the estimated C stock at the onset of settlement in the early 1970’s. Results from the participatory assessments predict that, in 2024 and in absence of a CDM project, the C stocks will decline from 301,859 t C in 2004 to 155,730 t C, which constitutes a reduction of 52%. The scenario with CDM estimates C stocks of 305,853 t C for 2024, a value slightly superior to the 2004 value. In the TC there is ground to believe that cattle ranching is likely to become an ever more important activity as the population is young and growing and cannot easily move elsewhere. Forests tend to be cleared for cultivation while pastures are established on short fallows. Our baseline scenario underlines the potential for a CDM project to make a significant difference in the future C stocks of this landscape.  相似文献   
97.
Congenital syphilis (CS) rates reached a 20-year high in the United States in 2018. Unlike previous years, most babies diagnosed with CS were born to mothers who received prenatal care, indicative of the need for better provider education and guideline adherence. Current rates suggest that screening for syphilis should be performed at the first prenatal care visit and twice during the third trimester. There are two diagnostic algorithms available for use in the United States (traditional and reverse) and providers must understand how to perform each algorithm. Treatment should be administered according to stage of syphilis per Centers for Disease Control recommendations with best neonatal outcomes seen when treatment is initiated >30 days before delivery. Benzathine Penicillin G remains the only recommended treatment of syphilis during pregnancy. In viable pregnancies, a pretreatment ultrasound is recommended to identify sonographic evidence of fetal infection and treatment should be initiated with continuous fetal monitoring to evaluate for the Jarisch-Herxheimer reaction which can cause preterm labor and fetal distress. After adequate syphilotherapy, a fourfold decline in maternal nontreponemal titers may not be observed by delivery and does not correlate with rates of CS.  相似文献   
98.
This review article outlines harmful algal bloom (HAB) monitoring practices in New Zealand and highlights the shift from light microscope (LM)-based identification and quantification of the early 1990s to the use of molecular tools to support the HAB monitoring programmes two decades later. Published research and available client information from the monitoring programmes have been reviewed; HAB events and programme changes are highlighted. The current HAB monitoring practices allow for rapid determination of potential biotoxin issues for the shellfish industry and of potential ichthyotoxic events for finfish farmers. The use of molecular tools, including quantitative PCR, has improved risk assessments for those HAB species that are difficult to differentiate to species level using LM. This has enabled rapid feedback to aquaculture managers during HAB events. Tests for biotoxins in flesh remain the regulatory tools for commercially harvested shellfish, but this is supported by the weekly phytoplankton monitoring data. Recreational (non-commercial) shellfish harvesting and commercial finfish aquaculture rely solely on phytoplankton monitoring to assess the biotoxin risk. HAB monitoring in New Zealand continues to maintain internationally recognised standards, and the government-funded research programmes feed the latest knowledge and technical methods into the programmes. The early dependence on light microscopy continues but is now supported by molecular tools, with a view to employing multi-species detection systems in the future. The traditional mouse bioassay test has been fully replaced by chemical tests.  相似文献   
99.
We have numerically modeled the breakdown of small quantities of several chlorinated hydrocarbons (CH3CI, CH2CI2, CHCI3, CCI4, C2H3CI, and C2H5CI) in a lean mixture of combustion products between 800 and 1480 K. This simulates the fate of poorly atomized waste in a liquid-Injection Incinerator. Kinetics calculations were performed using the CHEMKIN and SENKIN programs, with a reaction mechanism that was developed at Louisiana State University to model flat-flame burner experiments.

A 99.99-percent destruction efficiency was attained In one second at temperatures ranging from 1280 to 960 K, with CCI4 requiring the highest temperature for destruction and C2H5CI the lowest. For all compounds except C2H5CI, there was a range of temperatures at which byproducts accounted for several percent of the elemental chlorine at the outlet. The more heavily chlorinated compounds formed more byproducts even though the amount of elemental chlorine was the same in all cases. The sensitivity of results to residence time, equivalence ratio, temperature profile, and the presence of additional chlorine, was examined for the case of CHCI3.  相似文献   
100.
Environmental Science and Pollution Research - Multi-biological level assessments have become great tools to evaluate the health of aquatic ecosystems. Using this approach, a complementary study...  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