全文获取类型
收费全文 | 706篇 |
免费 | 12篇 |
国内免费 | 18篇 |
专业分类
安全科学 | 67篇 |
废物处理 | 23篇 |
环保管理 | 158篇 |
综合类 | 127篇 |
基础理论 | 184篇 |
环境理论 | 3篇 |
污染及防治 | 96篇 |
评价与监测 | 48篇 |
社会与环境 | 21篇 |
灾害及防治 | 9篇 |
出版年
2023年 | 6篇 |
2022年 | 7篇 |
2021年 | 9篇 |
2020年 | 9篇 |
2019年 | 15篇 |
2018年 | 12篇 |
2017年 | 30篇 |
2016年 | 29篇 |
2015年 | 22篇 |
2014年 | 21篇 |
2013年 | 44篇 |
2012年 | 25篇 |
2011年 | 41篇 |
2010年 | 23篇 |
2009年 | 34篇 |
2008年 | 48篇 |
2007年 | 39篇 |
2006年 | 41篇 |
2005年 | 31篇 |
2004年 | 21篇 |
2003年 | 27篇 |
2002年 | 24篇 |
2001年 | 12篇 |
2000年 | 13篇 |
1999年 | 10篇 |
1998年 | 12篇 |
1997年 | 14篇 |
1996年 | 7篇 |
1995年 | 10篇 |
1994年 | 8篇 |
1993年 | 14篇 |
1992年 | 6篇 |
1991年 | 7篇 |
1990年 | 3篇 |
1989年 | 7篇 |
1988年 | 8篇 |
1987年 | 7篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1977年 | 1篇 |
排序方式: 共有736条查询结果,搜索用时 15 毫秒
701.
We sampled residues from high-order and low-order blow-in-place detonations of mortars and projectiles filled with Composition B (Comp B), a TNT and RDX mixture. Our goals were to (1) characterize the types of explosive particles, (2) estimate the explosive 'footprint' for different munitions, and (3) estimate the mass of Comp B remaining after each detonation. The aerial deposition of Comp B particles helps estimate how large of an area is contaminated by a low-order detonation and how best to sample residue resulting from different rounds. We found that the high-order detonations deposited microgram to milligram quantities whereas the low-order detonations deposited gram quantities of Comp B. For the high-order detonations the concentration of Comp B in the residue decreased as a function of distance from the blast. The low-order tests scattered centimeter-sized chunks and millimeter-sized or smaller particles of Comp B. The chunks were randomly scattered whereas the number of millimeter-sized particles decreased with distance from the detonation. For both high- and low-order detonations we found that the smaller munitions deposited less Comp B than the larger munitions and deposited it closer to the detonation point. 相似文献
702.
Organohalogen chemicals in human blood from the United Kingdom 总被引:1,自引:0,他引:1
Thomas GO Wilkinson M Hodson S Jones KC 《Environmental pollution (Barking, Essex : 1987)》2006,141(1):30-41
Blood serum from 154 volunteers at 13 UK locations in 2003 were analysed for a range of PCBs, organochlorine pesticides and PBDEs. HCB, p,p'-DDE and p,p'-DDT and beta-HCH were the dominant organochlorine pesticides in most samples. BDEs 47, 99, 100, 153, 154 and 183 were the most regularly detected PBDEs. This study is the first report of BDE209 in UK human blood (found in 11 samples, range < 15-240 ng/g lipid). Concentration and age correlated for the less easily metabolised PCBs, p,p'-DDT and p,p'-DDE, HCB and HCHs. With increasing age females tended to have lower concentrations of the more chlorinated PCBs than males. Similar PBDE concentrations, and distributions, to those reported in the general population in Sweden in 2002 were found, despite differences in historical PBDE production and usage. There is increasing regulation to control persistent and bioaccumulative chemicals, and establishing human exposure will help to identify substances which should be urgently phased out. 相似文献
703.
Luigi Spezia Susan L. Cooksley Mark J. Brewer David Donnelly Angus Tree 《Environmental and Ecological Statistics》2014,21(3):487-505
The investigation of species distributions in rivers involves data which are inherently sequential and unlikely to be fully independent. To take these characteristics into account, we develop a Bayesian hierarchical model for mapping the distribution of freshwater pearl mussels in the River Dee (Scotland). At the top of the hierarchy the likelihood is used to describe the sequence of sites in which mussels were observed or not. Given that false observations can occur, and that “not observed” means both that the species was not present and that it was not observed, a Markov prior is introduced at the second level of the hierarchy to represent the sequence of sites in which mussels are estimated to occur. The Markov prior allows modelling the spatial dependency between neighbouring sites. A third level in the hierarchy is given by the representation of the transition probabilities of the Markov chain in terms of site-specific explanatory variables, through a logistic regression. The selection of the explanatory variables which influence the Markov process is performed by means of a simulation-based procedure, in the complex case of association between covariates. Four features were found to be associated with reduced chance of finding a local mussel population: tributaries, bridges, dredging, and waste water treatment works. These results complement the results of a previous study, providing new evidence for the causes of the deterioration of a highly threatened species. 相似文献
704.
Rindy C. Anderson Susan Peters Stephen Nowicki 《Behavioral ecology and sociobiology》2014,68(3):437-447
A growing number of studies show that learning about male mating signals can shape the way females discriminate among males and may influence the evolution of both female preferences and the male traits under selection. Female songbirds commonly prefer local songs over foreign songs from a different population. In some species, however, the extent of variation among songs sung by different males within a population is as great as the variation observed between populations, raising the question of how females are able to discriminate local from foreign songs. Here, we report that laboratory-reared female swamp sparrows (Melospiza georgiana) not only show a preference for the particular song types with which they were tutored as compared with both foreign songs and unfamiliar local songs but also show preference for unfamiliar local songs over unfamiliar foreign songs. An acoustic analysis comparing tutor songs and those presented as unfamiliar local and foreign songs suggests that female swamp sparrows might be attuned to the specifics of local note phonology when assessing the attractiveness of unfamiliar songs. Our results demonstrate that early auditory experience influences response to geographic song variation in female swamp sparrows, and suggest the possibility that female songbirds may generalize what they learn from songs early in life to novel songs heard in adulthood. Additional work is needed to evaluate the contribution of unlearned predispositions for local song. 相似文献
705.
The impact of universalistic versus particularistic criteria on academic hiring has been receiving growing attention in recent years. Yet, most studies conducted on hiring norms in academy and management academy have ignored the impact of social capital, particularly structural social capital, a particularistic attribute, on occupational outcomes. This could lead to a partial if not misleading view of the sociology of hiring in management academy. We utilize a novel approach, focusing on academic departments' structural social capital in the form of network centrality (based on cumulative PhD exchange networks), and explore how this type of centrality impacts job seekers' occupational prestige for new academic jobs in management departments and early career quality publications. We find that although merit‐based criteria such as publications matter somewhat, academic network centrality explains significant variance in obtaining prestigious jobs. Paradoxically, we find that academic network centrality does not explain early career publications. We discuss the implications of our findings for management science. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
706.
707.
Melatonin and serotonin are indoleamine neurohormones that function as photoperiod signals in many species and have recently been found in St. John's wort, a medicinal plant used in the treatment of depression. There is no known role for melatonin in higher plants but melatonin functions as a signal of changes in photoperiod in other species. In the current study, serotonin and melatonin were quantified during flower development. Higher concentrations of serotonin were found in flower buds at the tetrad stage of microspore development and higher melatonin concentrations were detected during uninucleate mircosporogenesis. Additionally, the regeneration potential of isolated anthers was highest in the same stage that had elevated melatonin concentrations. These data provide the first evidence of the presence of melatonin during flower development and raise many questions about the potential roles of serotonin and melatonin as regulatory molecules in the reproductive flexibility of higher plants. 相似文献
708.
Susan Clement Wilson Marleen Susman Sharon Bain Monica Wohlferd Daniel L. Van Dyke Art Daniel Beverly White R. J. McKinlay Gardner 《黑龙江环境通报》2002,22(8):681-685
We present six cases of 47,+i(5p)/46 mosaicism diagnosed at chorionic villus sampling (CVS), this being the first prospective series to be reported. The clinical indication in each was advanced maternal age. Further prenatal studies in four (amniocentesis, plus fetal blood sampling in one) did not show the isochromosome. In one case, subsequent amniocentesis showed 1/48 in situ colonies with the isochromosome, but fetal blood was karyotypically normal. These five pregnancies resulted in phenotypically normal livebirths; further normal follow-up reports (from age 4 months through 4 years) are noted in four of these. Analysis of placental tissue in one case confirmed the presence of the i(5p) mosaicism. In the remaining case, in which 100% of CVS cultured cells had the i(5p), the pregnancy was terminated. Fetal skin fibroblasts did not show the i(5p). Thus, in none of these six cases was true fetal mosaicism detected, nor an abnormal phenotype noted. We suggest that a 47,+i(5p)/46 karyotype, detected at CVS, may frequently reflect confined placental mosaicism. In addition, we report a case of the primary diagnosis of 47,+i(5p)/46 mosaicism at amniocentesis. The infant appeared normal at birth, but a brain malformation was subsequently identified. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
709.
710.