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   328篇
  免费   14篇
  国内免费   7篇
安全科学   29篇
废物处理   16篇
环保管理   57篇
综合类   47篇
基础理论   90篇
污染及防治   68篇
评价与监测   16篇
社会与环境   20篇
灾害及防治   6篇
  2023年   6篇
  2022年   3篇
  2021年   7篇
  2020年   7篇
  2019年   6篇
  2018年   8篇
  2017年   17篇
  2016年   14篇
  2015年   10篇
  2014年   11篇
  2013年   19篇
  2012年   18篇
  2011年   41篇
  2010年   19篇
  2009年   21篇
  2008年   18篇
  2007年   20篇
  2006年   14篇
  2005年   12篇
  2004年   11篇
  2003年   4篇
  2002年   3篇
  2001年   6篇
  2000年   5篇
  1999年   2篇
  1998年   1篇
  1997年   1篇
  1996年   4篇
  1995年   7篇
  1994年   3篇
  1993年   3篇
  1992年   6篇
  1991年   3篇
  1990年   1篇
  1989年   2篇
  1988年   3篇
  1987年   1篇
  1986年   2篇
  1984年   1篇
  1983年   3篇
  1982年   1篇
  1981年   1篇
  1979年   1篇
  1977年   1篇
  1975年   1篇
  1971年   1篇
排序方式: 共有349条查询结果,搜索用时 15 毫秒
321.
Cleaner production audit demonstration projects were carried out in two Chinese case factories as part of a project co-sponsored by the Illinois Environmental Protection Agency and China's State Environmental Protection Administration. Audit results at both factories were characterized by implementation of predominantly low- or no-cost options, notable reductions in water pollution, and incomplete financial benefit analyses. Two reasons explain the financial benefit analyses' apparent weakness. First, factory audit teams were inexperienced in the techniques and procedures used to determine the economic benefits of cleaner production options. Second, motivations project personnel had for participating in the demonstration projects were not centered on attaining the monetary benefits of implementing cleaner production. Instead, other factors related to the international nature of the project, such as a high degree of state level oversight and prestige, were more influential in affecting the behavior of project personnel.  相似文献   
322.
323.
Second trimester biomarkers were initially introduced with the intent of screening for neural tube defects and then subsequently for Down syndrome. It was soon realized that these markers can be indirect evidence of abnormal placentation and, therefore, can be used for screening for adverse pregnancy outcomes. Several new biomarkers have subsequently been described with conflicting findings regarding their efficiency for screening for adverse pregnancy outcomes. Although a biologically feasible mechanism has been proposed for the role of these biomarkers, they still fall short of an ideal screening test to be clinically useful. © 2014 John Wiley & Sons, Ltd.  相似文献   
324.

Background

Disease severity is important when considering genes for inclusion on reproductive expanded carrier screening (ECS) panels. We applied a validated and previously published algorithm that classifies diseases into four severity categories (mild, moderate, severe, and profound) to 176 genes screened by ECS. Disease traits defining severity categories in the algorithm were then mapped to four severity-related ECS panel design criteria cited by the American College of Obstetricians and Gynecologists (ACOG).

Methods

Eight genetic counselors (GCs) and four medical geneticists (MDs) applied the severity algorithm to subsets of 176 genes. MDs and GCs then determined by group consensus how each of these disease traits mapped to ACOG severity criteria, enabling determination of the number of ACOG severity criteria met by each gene.

Results

Upon consensus GC and MD application of the severity algorithm, 68 (39%) genes were classified as profound, 71 (40%) as severe, 36 (20%) as moderate, and one (1%) as mild. After mapping of disease traits to ACOG severity criteria, 170 out of 176 genes (96.6%) were found to meet at least one of the four criteria, 129 genes (73.3%) met at least two, 73 genes (41.5%) met at least three, and 17 genes (9.7%) met all four.

Conclusion

This study classified the severity of a large set of Mendelian genes by collaborative clinical expert application of a trait-based algorithm. Further, it operationalized difficult to interpret ACOG severity criteria via mapping of disease traits, thereby promoting consistency of ACOG criteria interpretation.
  相似文献   
325.
We examined the potential impacts of future climate change on the distribution and production of Atlantic cod (Gadus morhua) on the northeastern USA’s continental shelf. We began by examining the response of cod to bottom water temperature changes observed over the past four decades using fishery-independent resource survey data. After accounting for the overall decline in cod during this period, we show that the probability of catching cod at specified locations decreased markedly with increasing bottom temperature. Our analysis of future changes in water temperature was based on output from three coupled atmosphere–ocean general circulation models under high and low CO2 emissions. An increase of <1.5°C is predicted for all sectors under the low emission scenario in spring and autumn by the end of this century. Under the high emission scenario, temperature increases range from ~2°C in the north to >3.5°C in the Mid-Atlantic Bight. Under these conditions, cod appear vulnerable to a loss of thermal habitat on Georges Bank, with a substantial loss of thermal habitat farther south. We also examined temperature effects on cod recruitment and growth in one stock area, the Gulf of Maine, to explore potential implications for yield and resilience to fishing. Cod survival during the early life stages declined with increasing water temperatures, offsetting potential increases in growth with warmer temperatures and resulting in a predicted loss in yield and increased vulnerability to high fishing mortality rates. Substantial differential impacts under the low versus high emission scenarios are evident for cod off the northeastern USA.  相似文献   
326.
A fundamental challenge to estimating population size with mark-recapture methods is heterogeneous capture probabilities and subsequent bias of population estimates. Confronting this problem usually requires substantial sampling effort that can be difficult to achieve for some species, such as carnivores. We developed a methodology that uses two data sources to deal with heterogeneity and applied this to DNA mark-recapture data from grizzly bears (Ursus arctos). We improved population estimates by incorporating additional DNA "captures" of grizzly bears obtained by collecting hair from unbaited bear rub trees concurrently with baited, grid-based, hair snag sampling. We consider a Lincoln-Petersen estimator with hair snag captures as the initial session and rub tree captures as the recapture session and develop an estimator in program MARK that treats hair snag and rub tree samples as successive sessions. Using empirical data from a large-scale project in the greater Glacier National Park, Montana, USA, area and simulation modeling we evaluate these methods and compare the results to hair-snag-only estimates. Empirical results indicate that, compared with hair-snag-only data, the joint hair-snag-rub-tree methods produce similar but more precise estimates if capture and recapture rates are reasonably high for both methods. Simulation results suggest that estimators are potentially affected by correlation of capture probabilities between sample types in the presence of heterogeneity. Overall, closed population Huggins-Pledger estimators showed the highest precision and were most robust to sparse data, heterogeneity, and capture probability correlation among sampling types. Results also indicate that these estimators can be used when a segment of the population has zero capture probability for one of the methods. We propose that this general methodology may be useful for other species in which mark-recapture data are available from multiple sources.  相似文献   
327.
The number of research studies in the humanitarian field is rising. It is imperative, therefore, that institutional review boards (IRBs) consider carefully the additional risks present in crisis contexts to ensure that the highest ethical standards are upheld. Ethical guidelines should represent better the specific issues inherent to research among populations grappling with armed conflict, disasters triggered by natural hazards, or health‐related emergencies. This paper seeks to describe five issues particular to humanitarian settings that IRBs should deliberate and on which they should provide recommendations to overcome associated challenges: staged reviews of protocols in acute emergencies; flexible reviews of modification requests; addressing violence and the traumatic experiences of participants; difficulties in attaining meaningful informed consent among populations dependent on aid; and ensuring reviews are knowledgeable of populations' needs. Considering these matters when reviewing protocols will yield more ethically sound research in humanitarian settings and hold researchers accountable to appropriate ethical standards.  相似文献   
328.
Natural and human‐caused disasters pose a significant risk to the health and well‐being of people. Journalists and news organisations can fulfil multiple roles related to disasters, ranging from providing warnings, assessing disaster mitigation and preparedness, and reporting on what occurs, to aiding long‐term recovery and fostering disaster resilience. This paper considers these possible functions of disaster journalism and draws on semi‐structured interviews with 24 journalists in the United States to understand better their approach to the discipline. A thematic analysis was employed, which resulted in the identification of five main themes and accompanying subthemes: (i) examining disaster mitigation and preparedness; (ii) facilitating recovery; (iii) self‐care and care of journalists; (iv) continued spread of social media; and (v) disaster journalism ethics. The paper concludes that disaster journalism done poorly can result in harm, but done well, it can be an essential instrument with respect to public disaster planning, management, response, and recovery.  相似文献   
329.
The spread of non-native invasive species is affected by human activity, vegetation cover, weather, and interaction with native species. We analyzed data from a 17-year study of the distribution of the non-native Argentine ant (Linepithema humile) and the native winter ant (Prenolepis imparis) in a preserve in northern California (U.S.A.). We conducted logistic regressions and used model selection to determine whether the following variables were associated with changes in the distribution of each species: presence of conspecifics at neighboring sites, distance to development (e.g., roads, buildings, and landscaped areas), proportion of vegetation cover taller than 0.75 m, elevation, distance to water, presence of both species at a site, temperature, and rainfall. Argentine ants colonized unoccupied sites from neighboring sites, but the probability of appearance and persistence decreased as distance to development, vegetation cover, and elevation increased. Winter ants appeared and persisted in sites with relatively high vegetation cover (i.e., highly shaded sites). Presence of the 2 species was negatively associated in sites with high vegetation cover (more winter ants) and sites near development (more Argentine ants). Probability of colonization of Argentine ants decreased where winter ants were most persistent. At sites near development within the preserve, abundant Argentine ant populations may be excluding winter ants. The high abundance of Argentine ants at these sites may be due to immigration from suburban areas outside the preserve, which are high-quality habitat for Argentine ants. In the interior of the preserve, distance from development, low-quality habitat, and interaction with winter ants may in combination exclude Argentine ants. Interactions among the variables we examined were associated with low probabilities of Argentine ant colonization in the preserve.  相似文献   
330.
Globalization of human infectious disease   总被引:1,自引:0,他引:1  
Smith KF  Sax DF  Gaines SD  Guernier V  Guégan JF 《Ecology》2007,88(8):1903-1910
Globalization has facilitated the spread of numerous infectious agents to all corners of the planet. Analysis of the Global Infectious Disease and Epidemiology Network (GIDEON) database quantitatively illustrates that the globalization of human infectious agents depends significantly on the range of hosts used. Infectious agents specific to humans are broadly and uniformly distributed, whereas zoonotic infectious agents are far more localized in their geographical distribution. Moreover, these patterns vary depending on transmission mode and infectious agent taxonomy. This dichotomy is unlikely to persist if certain aspects of globalization (for example, exotic species introductions) continue unabated. This raises a serious concern for public health and leaves nations with the task of determining the infectious agents that have the greatest potential to establish within their borders. At the advent of a century characterized by an apparent increase in emerging infectious diseases, these results have critical implications for public-health policy and future research pathways of infectious disease ecology.  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