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   2239篇
  免费   17篇
  国内免费   91篇
安全科学   106篇
废物处理   210篇
环保管理   280篇
综合类   293篇
基础理论   392篇
环境理论   1篇
污染及防治   783篇
评价与监测   193篇
社会与环境   74篇
灾害及防治   15篇
  2023年   11篇
  2022年   33篇
  2021年   36篇
  2020年   12篇
  2019年   41篇
  2018年   70篇
  2017年   58篇
  2016年   78篇
  2015年   54篇
  2014年   67篇
  2013年   178篇
  2012年   123篇
  2011年   143篇
  2010年   96篇
  2009年   129篇
  2008年   134篇
  2007年   144篇
  2006年   128篇
  2005年   114篇
  2004年   105篇
  2003年   97篇
  2002年   88篇
  2001年   62篇
  2000年   35篇
  1999年   24篇
  1998年   20篇
  1997年   23篇
  1996年   16篇
  1995年   18篇
  1994年   18篇
  1993年   19篇
  1992年   10篇
  1991年   19篇
  1990年   10篇
  1989年   9篇
  1988年   10篇
  1986年   7篇
  1985年   8篇
  1984年   7篇
  1983年   7篇
  1982年   10篇
  1981年   10篇
  1980年   9篇
  1978年   6篇
  1976年   5篇
  1974年   4篇
  1973年   5篇
  1972年   6篇
  1971年   6篇
  1969年   5篇
排序方式: 共有2347条查询结果,搜索用时 13 毫秒
801.
Hawaii possesses abundant geothermal resources and rare native wildlife. Geothermal energy development has not posed a threat to native wildlife in the past, but development potential has recently reached a level at which concern for native wildlife is warranted.Potential geothermal resource areas in Hawaii intersect important native forest and endangered species habitat. The ability of existing laws to constrain development in these areas is in question. State and federal endangered species and environmental reporting laws have little ability to constrain geothermal development on private land. Hawaii's Land Use Law had been viewed by conservationists as protecting natural areas important to native wildlife, but recent decisions of the state Land Board sharply challenge this view.While this dispute was being resolved in the courts, the state legislature passed the Geothermal Subzone Act of 1983. Wildlife value was assessed in the geothermal subzone designation process mandated by this act, but the subzones designated primarily reflected inappropriate developer influence. All areas in which there was developer interest received subzone designation, and no area in which there was no developer interest was subzoned. This overriding emphasis on developer interest violated the intent of the sub-zone act, and trivialized the importance of other assessment criteria, among them native wildlife values.  相似文献   
802.
803.
Considerable concern has arisen over the possibility that the discharge of taconite tailings into Lake Superior could affect algal primary productivity. In 1972, primary productivity studies utilizing the carbon-14 technique were run in the Silver Bay area. Samples were collected and analyzed on a weekly basis for a three month period that included a five week plant shutdown period. Resultant productivity data indicate that there is no apparent relationship between primary productivity and the discharge of taconite tailings. Productivity trends in the Silver Bay area tend to conform to the known seasonal behavior of phytoplankton in western Lake Superior.  相似文献   
804.
Investigation into local peoples’ perceptions can produce useful information that could be incorporated into the decision-making process to help resolve environmental problems. Within the arena of land degradation, a number of studies have also been conducted to explore local peoples’ views of the problem. However, the perceptions of land-degrading practices of the general public have so far not been actively solicited. This study aimed to contribute to this area of research by adopting the psychometric scaling technique to empirically explore the lay public’s ecological risk perceptions of land-degrading activities in Minqin County in Gansu Province, northern China. The primary data were collected via a questionnaire survey (n = 1,138) administered between 14 and 31 December 2002. The major findings of the survey were: (1) Respondents perceived the ecological risks posed by different land-degrading activities to be different. (2) There was a considerable incongruence in the way in which mining of groundwater was conceived by experts and laymen, respectively. (3) Respondents were pretty unsure of expert knowledge. (4) Respondents’ ecological risk perceptions were significantly affected by their personal attributes. As far as the policy implications of these findings are concerned, this study accentuates that we must be aware of, and involved in, the environmental perceptions of the lay public in order to succeed in guiding any human-environment tensions along more sustainable trajectories and navigating the transition to sustainability.  相似文献   
805.
Multivariate Analysis of the Ecoregion Delineation for Aquatic Systems   总被引:1,自引:0,他引:1  
The ecoregion concept is a popular method of understanding the spatial distribution of the environment', however, it has yet to be adequately demonstrated that the environment is distributed in accordance with these bounded units. In this paper, we generated a testable hypothesis based on the current usage of ecoregions: the ecoregion classification will allow for discrimination between lakes of different water quality. The ecoregion classification should also be more effective better than a comparably scaled classification based on political boundaries, land-use class, or random grouping. To test this hypothesis we used the Environmental Monitoring and Assessment Program (EMAP) lake water chemistry data from the northeast United States. The water chemistry data were reduced to four components using principal component analysis. For comparison to an optimal grouping of these data we used K-means cluster analysis to define the extent at which these lakes could be segregated into distinct classes. Jackknifed discriminant analysis was used to determine the classification rate of ecoregions, the three alternative spatial classification methods, and the clustering algorithm. The classification based on ecoregions was successful for 35% of the lakes included in this study, in comparison to the clustered groups accuracy of 98%. These results suggest that the large scale spatial distribution of ecosystem types is more complicated than that suggested by the present ecoregion boundaries. Further tests of ecoregion delineations are needed and alternative large-scale management strategies should be investigated.  相似文献   
806.
We simulated the long range transport of dust emitted from dust storms that occurred in China by using a global three-dimensional chemical transport model. A modified dust emission flux scheme and a nonlocal diffusion scheme for determining the atmospheric eddy diffusivity in the atmospheric boundary layer were implemented to improve the chemical transport model. We examined the dust transport by comparing the model results with TOMS satellite images. The model calculated monthly total deposition of dust masses were used for comparison with the measurements collected at sampling stations in Japan, and good agreement was found. The model generally reproduced the temporal and spatial variations of dust reasonably well.  相似文献   
807.
This study examined the fate of seismic lines utilized in oil and gas exploration in Canada's western Boreal Plains. It retrospectively followed the persistence, recovery and developmental transition of seismic lines established between the 1960s and the mid-1970s through to 2003. We examined lines that passed through three forest types; aspen, white spruce, and lowland black spruce. In general, the recovery rates of seismic lines to woody vegetation were low. After 35 years, 8.2% of seismic lines across all forest types had recovered to greater than 50% cover of woody vegetation. Only the upland forest types recovered; aspen and white spruce. Most seismic lines ( approximately 65% at 35 years) remained in a cleared state with a cover of low forbs. The most common transition for seismic lines was to tracked access ( approximately 20% at 35 years). Transition to other anthropogenic developments such as roads, pipelines, buildings, and timber harvest blocks was 5% after 35 years. The pulse of industrial activity initiated in the mid-1990s greatly increased the transition rate of seismic to tracked access for a short period of time. The discussion focused on natural and anthropogenic factors that hinder recovery and on the management directions that would facilitate greater recovery rates.  相似文献   
808.
Environmental Science and Pollution Research - Mosquitoes are the underlying cause of various public health and economic problems. In this study, patterns of mosquito occurrence were analyzed based...  相似文献   
809.
Lee CC  Guo YL  Kuei CH  Chang HY  Hsu JF  Wang ST  Liao PC 《Chemosphere》2006,65(3):436-448
A pentachlorophenol (PCP) manufacturing plant in southern Taiwan discontinued production in 1989. The site of the abandoned plant was heavily contaminated by PCDD/PCDFs, impurities formed in the PCP production process. Serum samples collected from 27 residents living near the deserted plant were evaluated to determine whether this contamination had associated serum levels of PCDD/PCDFs in local residents. The average level of 17 tested congeners ranged from 556 to 5240 pg/g lipid (mean, 1670 pg/g lipid). The corresponding 2,3,7,8-TCDD toxicity equivalent quotient values calculated by international toxicity equivalent factors (I-TEFs) and those recommended by WHO (WHO-TEFs) were 47.2 pg I-TEQ/g lipid and 53.4 pg WHO-TEQ/g lipid, respectively. Levels in other parts of Taiwan typically range from 15 to 20 pg WHO-TEQ/g lipid; therefore, it is likely that the heavily contaminated plant site caused these unusually high serum levels. The average PCDD/PCDF levels of 29 fish-tissue and nine soil samples collected from the sea reservoir surrounding the abandoned PCP plant were also abnormally high: 8630 pg/g lipid (985 pg WHO-TEQ/g lipid) and 606000 pg/g-sample (922 pg WHO-TEQ/g-sample), respectively. Factor analysis indicated that the congener pattern of human serum samples collected from residents living near the abandoned PCP plant different from samples collected from other areas in Taiwan without known PCDD/PCDF pollution. Similar results were observed for the fish tissue and soil samples. The current study may have discovered a "hot spot" for elevated dioxin human exposure in Taiwan. The preliminary finding has raised a public health concern in the inspected area and requires further investigations to clarify the nature of the contamination and potential impact on the local environment and human health.  相似文献   
810.
This article is intended to provide background information on leachate management in closed landfill sites based on a comparison of two landfill sites and the identification of leachate characteristics depending on the final cover and the season. Site S is older and has no final cover, while site J is younger and has final capping. The results of leachate analysis from the two landfills show that the biological oxygen demand to chemical oxygen demand ratio decreases below 0.1 to the range 0.05–0.07 for site S, whereas the ratio at site J was in the range 0.08–0.55. The inorganic nitrogen concentration was in the range 169.9–386.1 mg/l with an average of 265.2 mg/l at site S. Ammonia nitrogen accounted for 98.9% of the total nitrogen. The absence of a final cover on closed landfill sites may contribute to the stabilization of such landfills due to flushing. The nitrogen content at landfill S dropped in the summer, whereas it decreased in the fall at site J. A higher fluctuation in the pollutant levels of organic matters and nitrogen at the younger landfill site was observed, compared to the older site, even though the younger site had final capping. Therefore, intensive leachate management should be arranged at the early stages after closing for proper treatment. Specifically, nitrogen management of leachate is a critical factor in treatment operations.  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