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   310篇
  免费   0篇
安全科学   2篇
废物处理   5篇
环保管理   6篇
综合类   149篇
基础理论   49篇
污染及防治   82篇
评价与监测   10篇
社会与环境   7篇
  2021年   3篇
  2018年   3篇
  2014年   4篇
  2013年   4篇
  2012年   4篇
  2011年   9篇
  2010年   16篇
  2009年   8篇
  2008年   14篇
  2007年   14篇
  2006年   14篇
  2005年   8篇
  2004年   6篇
  2003年   12篇
  2002年   8篇
  2001年   3篇
  2000年   6篇
  1998年   6篇
  1997年   5篇
  1991年   4篇
  1990年   3篇
  1987年   3篇
  1985年   3篇
  1984年   3篇
  1977年   3篇
  1969年   3篇
  1966年   4篇
  1965年   5篇
  1964年   7篇
  1963年   4篇
  1962年   7篇
  1961年   3篇
  1960年   5篇
  1958年   7篇
  1957年   6篇
  1956年   11篇
  1955年   9篇
  1954年   3篇
  1953年   4篇
  1952年   3篇
  1951年   4篇
  1950年   2篇
  1947年   4篇
  1934年   2篇
  1933年   2篇
  1930年   2篇
  1929年   2篇
  1925年   2篇
  1921年   2篇
  1918年   2篇
排序方式: 共有310条查询结果,搜索用时 31 毫秒
231.
Summary The attraction of permanently cohabiting males and females to their pair mate was assessed in a preference situation in which a subject was given a choice between its pair mate and a stranger of the mate's sex. Animals were tested in a choice apparatus, consisting of 1 cage housing the subject, 1 cage housing its pair mate, and 1 cage housing the strange stimulus animal. Wire mesh tunnels connected the subject's cage with that of each stimulus animal. Each tunnel was divided into 5 sections of equal length. During a series of 30-min choice tests, the subjects' location was scored every 10 sec as being in the home cage or in one of the sections of the tunnels leading to the cages of the other animals. In addition to these location scores, being at Zero Distance from a stimulus animal, as well as a number of behaviors directed at both stimulus animals, were recorded. Males were in closer proximity to their females than to strange females (Fig. 2), approached their females more frequently and directed more Tongue Displays and Sniffs at their mates (Figs. 3–5). Females did not prefer their males in terms of these behaviors (Figs. 2–5). Moreover, they directed a higher number of Gazes at strange males (Fig. 6). Both males and females were more frequently at Zero Distance from their pair mates than from strange stimulus animals and had more Nonaggressive Contacts with their pair mates (Figs. 7–8). These results suggest that males show a strong attachment to their female pair mates while females are attracted to their mates as well as to strange males.  相似文献   
232.
233.
Biochemische Genetik von Enzymen in der tierischen Entwicklung   总被引:1,自引:0,他引:1  
  相似文献   
234.
235.
236.
237.
238.
Triclosan (TCS) is a broad-spectrum bactericide, highly toxic to algae, which is released into the environment via wastewater effluents. Predicted no-effect concentrations (PNECs) for aquatic biota have been proposed in the literature, varying from 1.4 to 1,550 ng/L, reflecting contradicting protection goals. In this work, six rivers in the state of São Paulo were monitored for TCS and caffeine, a tracer for untreated sewage disposal, over a period of more than 1 year. From 71 samples analyzed, 32 contained TCS at concentrations above the limit of quantification, ranging from 2.2 to 66 ng/L, corresponding to a frequency of exceedance of the lowest PNEC of 86 % (six out of seven sites). No correlation between TCS and caffeine was observed, and one of the reasons for that could be the different use patterns in the local populations. Given the high values found in the investigated rivers, TCS seems to be a strong candidate in the priority list of compounds that should be regulated in Brazil to preserve the aquatic environment.  相似文献   
239.
Compassionate conservation is based on the ethical position that actions taken to protect biodiversity should be guided by compassion for all sentient beings. Critics argue that there are 3 core reasons harming animals is acceptable in conservation programs: the primary purpose of conservation is biodiversity protection; conservation is already compassionate to animals; and conservation should prioritize compassion to humans. We used argument analysis to clarify the values and logics underlying the debate around compassionate conservation. We found that objections to compassionate conservation are expressions of human exceptionalism, the view that humans are of a categorically separate and higher moral status than all other species. In contrast, compassionate conservationists believe that conservation should expand its moral community by recognizing all sentient beings as persons. Personhood, in an ethical sense, implies the individual is owed respect and should not be treated merely as a means to other ends. On scientific and ethical grounds, there are good reasons to extend personhood to sentient animals, particularly in conservation. The moral exclusion or subordination of members of other species legitimates the ongoing manipulation and exploitation of the living worlds, the very reason conservation was needed in the first place. Embracing compassion can help dismantle human exceptionalism, recognize nonhuman personhood, and navigate a more expansive moral space.  相似文献   
240.
Abstract

The follow-up of a cohort of adults from 29 European centers of the former European Community Respiratory Health Survey (ECRHS) I (1989–1992) will examine the long-term effects of exposure to ambient air pollution on the incidence, course, and prognosis of respiratory diseases, in particular asthma and decline in lung function. The purpose of this article is to describe the methodology and the European-wide quality control program for the collection of particles with 50% cut-off size of 2.5 µm aerodynamic diameter (PM2.5 ) in the ECRHS II and to present the PM2.5 results from the winter period 2000–2001.

Because PM2.5 is not routinely monitored in Europe, we measured PM2.5 mass concentrations in 21 participating centers to estimate background exposure in these cities. A standardized protocol was developed using identical equipment in each center (U.S. Environmental Protection Agency Well Impactor Ninety-Six [WINS] and PQ167 from BGI, Inc.). Filters were weighed in a single central laboratory. Sampling was conducted for 7 days per month for a year.

Winter mean PM2.5 mass concentrations (November 2000–February 2001) varied substantially, with Iceland reporting the lowest value (5 µg/m3) and northern Italy the highest (69 µg/m3). A standardized procedure appropriate for PM2.5 exposure assessmnt in a multicenter study was developed. We expect ECRHS II to have sufficient variation in exposure to assess long-term effects of air pollution in this cohort. Any bias caused by variation in the characteristics of the chosen monitoring location (e.g., proximity to traffic sources) will be addressed in later analyses. Given the homogenous spatial distribution of PM2.5 , however, concentrations measured near traffic are not expected to differ substantially from those measured at urban background sites.  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