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   1331篇
  免费   5篇
  国内免费   51篇
安全科学   72篇
废物处理   91篇
环保管理   115篇
综合类   97篇
基础理论   176篇
环境理论   1篇
污染及防治   543篇
评价与监测   208篇
社会与环境   75篇
灾害及防治   9篇
  2023年   34篇
  2022年   143篇
  2021年   135篇
  2020年   34篇
  2019年   49篇
  2018年   46篇
  2017年   64篇
  2016年   60篇
  2015年   41篇
  2014年   48篇
  2013年   148篇
  2012年   55篇
  2011年   82篇
  2010年   59篇
  2009年   43篇
  2008年   41篇
  2007年   41篇
  2006年   28篇
  2005年   25篇
  2004年   20篇
  2003年   20篇
  2002年   20篇
  2001年   25篇
  2000年   9篇
  1999年   12篇
  1998年   4篇
  1997年   9篇
  1996年   4篇
  1995年   2篇
  1994年   2篇
  1993年   2篇
  1992年   2篇
  1991年   7篇
  1990年   5篇
  1989年   4篇
  1988年   4篇
  1987年   5篇
  1986年   2篇
  1985年   7篇
  1984年   4篇
  1983年   4篇
  1982年   6篇
  1981年   4篇
  1980年   6篇
  1979年   7篇
  1978年   2篇
  1976年   2篇
  1962年   1篇
  1961年   1篇
  1959年   1篇
排序方式: 共有1387条查询结果,搜索用时 31 毫秒
931.
Earthquake 2001 in Bhuj region of Kachchh district of Gujarat(India) was one of the most devastating earthquakes in the Indian history. This earthquake has caused severe damage to human life and properties. The impact of earthquake on groundwater resources at many locations was significant. Steep rise in static water level due to earthquake was observed at Bhachau and Chandarani. At other location groundwater followed the declining trend.  相似文献   
932.
Electrophoretic analysis of loci controlling a variety of enzymes has been applied to samples of the Padstow mussel and typical Mytilus edulis L. living strictly sympatrically at Rock, Cornwall, England, in order to resolve the disputed status of the Padstow mussel. Small samples indicated similar monomorphic states at the GPDH, TO, MDH-2 loci and weak polymorphism at the 6 PGD locus in both types of mussel. The MDH-1 locus may be weakly polymorphic in the Padstow mussel and monomorphic in M. edulis. Large samples assayed for AP, LAP, PGM, and PHI produced data showing very large and highly significant differences in allele frequencies at three of these loci between the two groups of mussels separated on anatomical characters. At the LAP locus, significant deficiencies of heterozygotes were observed in both groups of mussels. A small percentage of mussels from Rock are difficult to assign with certainty to one or other group on anatomical and morphological criteria, but the genetic evidence indicates that most, if not all, such specimens are M. edulis. These genetic differences make it highly improbable that any significant degree of genetic exchange occurs between the two groups in nature and, taken together with the evidence of genetic resemblance of the Padstow mussel to M. galloprovincialis from Venice and that of Rock M. edulis to M. edulis, from the Gower peninsula of Wales we conclude that the Padstow mussel is indeed M. galloprovincialis.  相似文献   
933.
Entomological studies conducted during monsoon and post-monsoon season in Manipur State revealed the presence of fifty-five species of mosquitoes under ten genera. Out of the seventeen Anopheles species recorded, Anopheles aconitus, An. dirus and An. nivipes were recorded for the first time from the state. The present study has confirmed the existence of An. dirus, the major malaria vector in the Northeast from a selected area of the state. Among Culicines, four species viz., Aedes nigrostriatus, Malaya genurostris, Aediomyia catasticta and Toxorhynchites splendens which were not reported earlier from this state have been recorded in the present study. With the addition of these seven species of mosquitoes to the earlier record of mosquitoes so far reported from Manipur, the mosquito fauna swells up to one hundred and eleven including the major vectors of malaria of the Northeast and the potential vectors of Japanese encephalitis and dengue virus transmission in India.  相似文献   
934.
Intermittent exposure of tomato plants (cv. Pusa Ruby) to SO(2) at 286 microg m(-3) (3 h every heavy third day for 75 days) induced slight chlorosis of leaves. At 571 microg m(-3), considerable chlorosis with browning developed on the foliage. These symptoms were more pronounced and appeared earlier on SO(2)-exposed plants infected with Meloidogyne incognita race 1 (Mi), especially in post- and concomitant-inoculation exposures. Mi and/or SO(2) significantly reduced different parameters of plant growth. Synergistic (positive) interactions between SO(2) and Mi occurred in concomitant- and post-inoculation exposures at 286 and 571 microg m(-3), respectively. In other treatments, an antagonistic (negative) interaction was observed. However, in a few cases, additive effects of SO(2) and Mi were also recorded. Intensity of root-knot (galling) was enhanced at both concentrations of SO(2), while reproduction (egg mass production) of Mi was enhanced in concomitant-inoculation exposures at 286 microg m(-3) and inhibited at 571 micro m(-3). Exposure to SO(2) and/or Mi decreased the number and size of stomata but increased the number and length of trichomes on both the leaf surfaces. Stomatal aperture was significantly wider in the plants exposed to 571 microg SO(2) m(-3) alone and in pre-, post-, and concomitant-inoculation exposures at 286 or 571 microg m(-3). Stomatal aperture was directly related to foliar injury and reductions in growth, yield, and leaf pigments.  相似文献   
935.
936.
Having reponded to various crises since the Paris Sugar Convention 1864, the process of international commodity organization is now recognized as a positive means of securing expansion of world trade and of bringing about development in producing countries. But these objectives necessitate multi-dimensional measures. The supply-management techniques, hitherto the pivot of international commodity agreements, have proved to be inadequate. It is argued in this article that the trade and development objectives can be better achieved by the provision of varied measures; that a ‘GATT for primary commodities’ is among such measures; and that such an organization does not negate, but supplements, the existing system.  相似文献   
937.
Groundwater contamination by agricultural chemicals is a major environmental pollution issue nation-wide. The regulatory agencies of towns and counties face the problem of finding a methodology for assessing the ground-water contamination potential of a large number of agricultural pesticides. Because of the spatial nature of the problem and the limited data availability for comprehensive pesticide movement models, a contamination potential index was employed for preliminary assessment. A specially designed geographic information system was used to create ground-water contamination likelihood maps for a 1500 km2 area. The results suggest that this methodology can be used successfully for evaluating the relative contamination potential of a large number of pesticides over large areas with limited input data. A tentative approach for using this method for monitoring and registration of pesticides is also discussed.  相似文献   
938.
Use of biomass sorbents for oil removal from gas station runoff   总被引:1,自引:0,他引:1  
The use of biomass sorbents, which are less expensive and more biodegradable than synthetic sorbents, for oil removal from gas station runoff was investigated. A bench-scale flume experiment was conducted to evaluate the oil removal and retention capabilities of the biomass sorbents which included kapok fiber, cattail fiber, Salvinia sp., wood chip, rice husk, coconut husk, and bagasse. Polyester fiber, a commercial synthetic sorbent, was also experimented for comparison purpose. Oil sorption and desorption tests were performed at a water flow rate of 20 lmin-1. In the oil sorption tests, a 50 mgl(-1) of used engine oil-water mixture was synthesized to simulate the gas station runoff. The mass of oil sorbed for all sorbents, except coconut husk and bagasse, was greater than 70%. Cattail fiber and polyester fiber were the sorbents that provided the least average effluent oil concentrations. Oil selectivity (hydrophobic properties) and physical characteristics of the sorbents are the two main factors that influence the oil sorption capability. The used sorbents from the sorption tests were employed in the desorption tests. Results indicated that oil leached out of all the sorbents tested. Polyester fiber released the highest amount of oil, approximately 4% (mass basis) of the oil sorbed.  相似文献   
939.
This work is an investigation on the use of manganese oxides-modified diatomite (MOMD) for the removal of color from textile wastewaters. The modification of the diatomite was carried out by treatment with manganese oxides; delta-bimessite type resulted. The surface area, pH(ZPC), Fourier transform infrared (FTIR), and scanning electron microscopy of MOMD were studied. The influence of concentration, pH, particle size, and temperature on the adsorption capacities of methylene blue (MB) and hydrolyzed reactive black (RB) and reactive yellow (RY) was investigated. Key thermodynamic parameters such as deltaH degrees, deltaS degrees, and deltaG degrees were also determined. The deltaH degrees of MB and hydrolyzed RB and RY was +94.64, -143.1, and -38.78 kJ/mol, respectively, whereas the deltaG degrees values of -17.68, -27.93, and -23.26 kJ/mol were obtained, indicating a spontaneous process with low activation-energy requirements. The findings further indicated that coulomb interaction, molecular size, and orientation of the dye and its surface charge played an important role in the adsorption and attachment of the dyes to the bimessite layers of MOMD.  相似文献   
940.
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