全文获取类型
收费全文 | 810篇 |
免费 | 20篇 |
国内免费 | 8篇 |
专业分类
安全科学 | 24篇 |
废物处理 | 19篇 |
环保管理 | 209篇 |
综合类 | 114篇 |
基础理论 | 159篇 |
环境理论 | 1篇 |
污染及防治 | 225篇 |
评价与监测 | 43篇 |
社会与环境 | 36篇 |
灾害及防治 | 8篇 |
出版年
2023年 | 10篇 |
2022年 | 13篇 |
2021年 | 16篇 |
2020年 | 12篇 |
2019年 | 7篇 |
2018年 | 15篇 |
2017年 | 17篇 |
2016年 | 22篇 |
2015年 | 24篇 |
2014年 | 19篇 |
2013年 | 92篇 |
2012年 | 22篇 |
2011年 | 38篇 |
2010年 | 29篇 |
2009年 | 38篇 |
2008年 | 47篇 |
2007年 | 43篇 |
2006年 | 40篇 |
2005年 | 38篇 |
2004年 | 35篇 |
2003年 | 28篇 |
2002年 | 28篇 |
2001年 | 13篇 |
2000年 | 10篇 |
1999年 | 19篇 |
1998年 | 11篇 |
1997年 | 12篇 |
1996年 | 10篇 |
1995年 | 10篇 |
1994年 | 12篇 |
1993年 | 14篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 9篇 |
1989年 | 4篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1986年 | 2篇 |
1985年 | 15篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有838条查询结果,搜索用时 31 毫秒
161.
This article discusses an integrated management system that aligns and integrates the various environmental, health, and safety functions and disciplines. This model is easily adopted to provide performance measures required to satisfy Responsible Care®, ISO 14001, and the European Union EMAS requirements. 相似文献
162.
Greenhouse Gas Fluxes in Tropical and Temperate Agriculture: The need for a Full-Cost accounting of Global Warming Potentials 总被引:1,自引:0,他引:1
Agriculture's contribution to radiative forcing is principally through its historical release of carbon in soil and vegetation to the atmosphere and through its contemporary release of nitrous oxide (N2O) and methane (CHM4). The sequestration of soil carbon in soils now depleted in soil organic matter is a well-known strategy for mitigating the buildup of CO2 in the atmosphere. Less well-recognized are other mitigation potentials. A full-cost accounting of the effects of agriculture on greenhouse gas emissions is necessary to quantify the relative importance of all mitigation options. Such an analysis shows nitrogen fertilizer, agricultural liming, fuel use, N2O emissions, and CH4 fluxes to have additional significant potential for mitigation. By evaluating all sources in terms of their global warming potential it becomes possible to directly evaluate greenhouse policy options for agriculture. A comparison of temperate and tropical systems illustrates some of these options. 相似文献
163.
164.
Overview of case studies on recovery of aquatic systems from disturbance 总被引:13,自引:2,他引:13
Gerald J. Niemi Philip DeVore Naomi Detenbeck Debra Taylor Ann Lima John Pastor J. David Yount Robert J. Naiman 《Environmental management》1990,14(5):571-587
An extensive review of the published literature identified more than 150 case studies in which some aspect of resilience in
freshwater systems was reported. Approximately 79% of systems studied were lotic and the remainder lentic. Most of the stressor
types were chemical with DDT (N=29) and rotenone (N=15) the most common. The most common nonchemical stressors were logging
activity (N=16), flooding (N=8), dredging (N=3), and drought (N=7).
The variety of endpoints to which recovery could be measured ranged from sparse data for phytoplankton (N=13), periphyton
(N=6), and macrophytes (N=8) to relatively more data for fish (N=412) and macroinvertebrates (N=698). Unfortunately the same
characteristics were rarely measured consistently among sites. For example, with respect to fish, more than 30 different species
were studied and recovery was measured in many ways, most commonly on the basis of: (1) first reappearance of the species,
(2) return time of predisturbance densities, and (3) return time of predisturbance average individual size. Based on these
criteria, all systems in these studies seem to be resilient to most disturbances with most recovery times being less than
three years. Exceptions included when (1) the disturbance resulted in physical alteration of the existing habitat, (2) residual
pollutants remained in the system, or (3) the system was isolated and recolonization was suppressed. 相似文献
165.
166.
A. C. C. van Oppen E. J. Breslau-Siderius Ph. Stoutenbeek A. J. Pull Ter Gunne J. M. W. M. Merkus 《黑龙江环境通报》1991,11(12):915-920
Tuberous sclerosis is a single gene autosomal-dominant disorder, characterized by multiple hamartoma formation. It shows a wide variability of expression. Prenatal diagnosis by means of a DNA or biochemical marker is not yet possible. Ultrasound offers the only way to detect possible antenatal hamartoma formation, which is most commonly found in the central nervous system, the renal system, and the heart. We report a case of fetal involvement that appears unique because of the unusual location of a tumour in the neck of the fetus. 相似文献
167.
Maternal cell contamination was assessed in 18 macroscopically blood-stained amniotic fluid samples from male fetuses. The samples were analysed by double-target fluorescent in situ hybridization (ISH) with Y and X chromosome-specific probes. The only sample with an aberrant karyotype (47, XY, +18) was also analysed by hybridization with a chromosome 18-specific probe. An interpretation of extensive maternal cell contamination was made in two samples, one of which was the sample with trisomy 18. ISH with the chromosome 18-specific probe on this latter sample showed that the sensitivity of the ISH method for chromosome enumeration of uncultured amniotic fluid samples may be reduced in bloodstained samples. It was calculated that by using ISH for chromosome enumeration of the two extensively contaminated samples, a case of trisomy 21 might have been overlooked in both samples, while a case of trisomy 18 might only have been overlooked in one of the samples. It is concluded that ISH should not be used for chromosome enumeration of uncultured amniotic fluid samples that are macroscopically blood-stained without further technical developments. 相似文献
168.
To determine the genetic population structure of blue crabs (Callinectes sapidus Rathbun), electrophoretic allozyme analysis was performed on 750 individuals collected from 16 nearshore locations ranging from New York to Texas, USA. Twenty enzymes and non-enzymatic proteins coded by 31 presumptive loci were examined. Twenty-two loci were either monomorphic or polymorphic at less than theP
95 level; alleles for these polymorphic loci were geographically dispersed. Allele frequencies for three of the remaining polymorphic loci were homogeneous over all populations, as were levels of polymorphism and heterozygosity. Phenograms generated by the UPGMA (unweighted pair-group method using arithmetic averages) and distance Wagner methods exhibited no geographic pattern in the clustering of populations. Estimates ofN
em (effective number of migrants per generation between populations) indicated substantial gene flow, with aalues sufficiently high to infer panmixia between all blue crab populations from New York to Texas. However, despite this high level of gene flow, two striking patterns of geographic differentiation occurred: genetic patchiness and clinal variation. Allele frequencies atEST-2, GP-1, IDHP-2, DPEP-1, DPEP-2, andTPEP exhibited genetic patchiness on local and range-wide geographic scales, and allele frequencies atEST-2 varied temporally. Genetic patchiness in blue crabs is likely to be the result of the pre-settlement formation and subsequent settlement of genetically heterogeneous patches of larvae; allele frequencies of those larval patches may then be further modified through ontogeny by localized selection. In the Atlantic Ocean, a regional latitudinal cline ofEST-2 allele frequencies was superimposed on the range-wide genetic patchiness exhibited by that locus. This pattern against a background of high gene flow is highly likely to be maintained by selection. In estuaries along the Atlantic Ocean coast, a combination of low adult long-distance migration and a high retention rate of locally spawned larvae could serve to segregate populations and allow for the development of the geographic cline inEST-2. The Gulf of Mexico showed no apparent cline, perhaps due to long-distance migration of females in some regions of the Gulf, or to masking by genetic patchiness. These results emphasize the importance of both ecological and evolutionary time scales and structuring mechanisms in determining genetic population structure. 相似文献
169.
Directions in Conservation Biology: Comments on Caughley 总被引:4,自引:0,他引:4
Philip W. Hedrick Robert C. Lacy Fred W. Allendorf Michael E. Soulé 《Conservation biology》1996,10(5):1312-1320
The recent review by Caughley (1994) on approaches used in conservation biology suggested that there are two: the small population paradigm and the declining population paradigm. We believe that this division is overly simplistic and that it should not be perpetuated. Both the deterministic factors that reduce population size and the stochastic factors that lead to the final extinction of a small population are critical to consider in preventing extinction. Only through an overall and comprehensive effort, which we call inclusive population viability analysis, can extinction processes be understood and mitigated. In this context we discuss Caughley's comments about genetics, demography, and general population viability, with particular attention to cheetahs (Acinonyx jubatus) and Pacific salmon (Oncorhynchus sp. ) . 相似文献
170.
Persistent organic pollutants in mangrove food webs in Singapore 总被引:1,自引:0,他引:1
In this study, persistent organic pollutants were quantified in sediments, subsurface seawater, sea-surface microlayer and twenty-four biota species collected at two separate mangrove habitats in Singapore. Data confirmed the ubiquity of POPs, including polybrominated diphenyl ethers (PBDEs), in the marine environment of Singapore. A biomagnification phenomenon was observed amongst the species collected and analysed from both mangrove sites studied. Thunder crabs and fish displayed the highest POP levels. Congener profiles of PBDEs varied amongst mangrove biota species and suggested different metabolic pathways exist for flame retardants. Similarly, crab species showed an ability to metabolize chlordane insecticide. 相似文献