全文获取类型
收费全文 | 40560篇 |
免费 | 431篇 |
国内免费 | 354篇 |
专业分类
安全科学 | 1280篇 |
废物处理 | 1886篇 |
环保管理 | 5266篇 |
综合类 | 6268篇 |
基础理论 | 10784篇 |
环境理论 | 12篇 |
污染及防治 | 10106篇 |
评价与监测 | 2850篇 |
社会与环境 | 2637篇 |
灾害及防治 | 256篇 |
出版年
2022年 | 363篇 |
2021年 | 385篇 |
2020年 | 265篇 |
2019年 | 312篇 |
2018年 | 568篇 |
2017年 | 620篇 |
2016年 | 942篇 |
2015年 | 712篇 |
2014年 | 1139篇 |
2013年 | 3326篇 |
2012年 | 1359篇 |
2011年 | 1817篇 |
2010年 | 1512篇 |
2009年 | 1537篇 |
2008年 | 1847篇 |
2007年 | 1802篇 |
2006年 | 1622篇 |
2005年 | 1403篇 |
2004年 | 1374篇 |
2003年 | 1325篇 |
2002年 | 1249篇 |
2001年 | 1532篇 |
2000年 | 1096篇 |
1999年 | 663篇 |
1998年 | 479篇 |
1997年 | 526篇 |
1996年 | 532篇 |
1995年 | 627篇 |
1994年 | 548篇 |
1993年 | 460篇 |
1992年 | 504篇 |
1991年 | 484篇 |
1990年 | 476篇 |
1989年 | 458篇 |
1988年 | 400篇 |
1987年 | 355篇 |
1986年 | 366篇 |
1985年 | 362篇 |
1984年 | 376篇 |
1983年 | 361篇 |
1982年 | 359篇 |
1981年 | 316篇 |
1980年 | 260篇 |
1979年 | 281篇 |
1978年 | 244篇 |
1977年 | 227篇 |
1975年 | 207篇 |
1974年 | 198篇 |
1973年 | 240篇 |
1972年 | 207篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
Russian Journal of Ecology - 相似文献
62.
63.
Dr. J. F. Bruch P. Metezeau N. Garcia-Fonknechten Y. Richard V. Tricottet B.-L. Hsi A. Kitzis C. Julien E. Papiernik 《黑龙江环境通报》1991,11(10):787-798
Three monoclonal antibodies (MAbs) against trophoblast (GB17, GB21, and GB25) and flow cytometry were used to sort trophoblast-like cells (TLCs) from peripheral blood of pregnant women. Sorted TLCs were processed for electron microscopy and fetal DNA amplification of the Y-specific sequences from mothers carrying male fetuses. At the ultra-structural level, most of the nucleated cells had the morphology of leucocytes, suggesting maternal contaminants, and we did not find the characteristic features of the free inter-villous trophoblast cells. Nevertheless, polymerase chain reaction (PCR) analysis showed an amplification of Y-specific sequences in two out of three samples of sorted TLCs. These results suggest that besides the maternal leucocytes, sufficient trophoblast nucleated fetal cells can be obtained using cell enrichment by sorting. This sensitive method holds promise for non-invasive prenatal diagnosis of fetal sex and if sufficient Y(positive) nuclei are found, for the diagnosis of selected numerical chromosome abnormalities. 相似文献
64.
Sustainable development of the earth's limited water and land resources is of paramount importance because of rising world population and existing conflicting demands for these resources. Enormous capital investment has been made in developing these resources, but now there is irrefutable evidence that such developments have led to major resource degradation. This includes problems of salinisation and damages to ecosystems. The countries predominantly affected by human induced salinisation are located in arid and semi-arid regions of the world and include Australia, China, Egypt, India, Pakistan, USSR, and USA. This paper describes the processes of salinisation, its impacts and the use of quantitative methods in salinity investigation and management. Australia is used as a case study of typical salinity problems and as a demonstration of the fruitful application of quantitative methods. The paper concludes that quantitative methods such as surface water and groundwater models are powerful design, management and predictive tools in salinity investigation. However, application of some models, such as those for unsaturated flow and transport and groundwater solute transport, are not widespread due to uncertainties in describing the complexity of the processes and the lack of hydrodispersive data. 相似文献
65.
The past two decades have witnessed an increase in the exploration for, and development of, mineral resources at Arctic latitudes. Such effort has resulted in the commencement of production at a number of different localities in close proximity to the ocean. Since proximity to a source of transportation for the conveyance of concentrates to the market is a primary requirement governing the economic decisions for the mine to proceed, it is logical that ore deposits near a coastline are primary targets for development.
Closely tied to coastal mining developments is the need to dispose of tailings and waste rock in the most economical manner. Prior to the advent of heightened public awareness and environmental concern, and the enactment of pollution legislation, disposal practices were largely based upon convenience. Currently, however, proposed disposal and operating practices receive closer scrutiny, with a view to providing adequate protection for aquatic resources and habitat. This paper summarizes some of the features of three Arctic mines, wastes from which enter the marine environment, and compares the disposal practices used at each to measures of environmental change as indicated by metal concentrations in various media. 相似文献
Closely tied to coastal mining developments is the need to dispose of tailings and waste rock in the most economical manner. Prior to the advent of heightened public awareness and environmental concern, and the enactment of pollution legislation, disposal practices were largely based upon convenience. Currently, however, proposed disposal and operating practices receive closer scrutiny, with a view to providing adequate protection for aquatic resources and habitat. This paper summarizes some of the features of three Arctic mines, wastes from which enter the marine environment, and compares the disposal practices used at each to measures of environmental change as indicated by metal concentrations in various media. 相似文献
66.
Mangrove Mapping Using Landsat Imagery and Aerial Photographs: Kemaman District, Terengganu, Malaysia 总被引:2,自引:0,他引:2
I. Sulong H. Mohd-Lokman K. Mohd-Tarmizi A. Ismail 《Environment, Development and Sustainability》2002,4(2):135-152
Classification and distribution of mangrove vegetation are vital information for the proper development of a mangrove management plan. In this study, classification for the mangroves of the district of Kemaman were done using both 1 : 5000 aerial photographs and Landsat TM imageries. The coverage by aerial photographs is limited to the coastal and estuarine areas only. Thus, for areas further upstream of the aerial photo coverage, Landsat TM imageries were used. Analysis of aerial photographs and remote sensing images revealed that the mangroves of Kemaman could be classified into 14 different classes of vegetation. All the 14 classes were identified from areas covered by the aerial photographs. For areas covered by the Landsat images only 7 classes of vegetation were identified. The accuracy for aerial photograph and Landsat images are 91.2% and 87.8%, respectively. It can be concluded that although both techniques are useful in determining the mangrove vegetation classes, the large 1 : 5000 aerial photographs are more accurate and provided more detailed information comparatively. 相似文献
67.
The effect of mountain relief and industrial air pollution on biometric parameters of pine stands was studied. The empirical–statistical models of the dependence of biometric characteristics on the parameters of forest sites were developed using raster modeling and multivariate analysis. The possibility of predicting changes in the biometric parameters at any site on the basis of these models is shown. 相似文献
68.
Freedman Boyd 《Journal of Agricultural and Environmental Ethics》1994,7(2):221-236
Is the use of electrical stunners adequately discharging our moral obligations with respect to the humane slaughter of poultry? Below, three separate lines of investigation show that we cannot give an unequivocal answer to this question. First, five potentially humane methods of poultry slaughter are examined. Electrical stunning is found to be an acceptable method of rendering birds unconscious before slaughter. However, we lack sufficient evidence to claim that it is the most humane method currently available. Second, surveys of poultry processing plants show that, with alarming frequency, a proper stun is not achieved. An investigation of the complexity of the electrical stun process shows the difficulties involved and suggests that under many on-the-floor slaughterhouse conditions, consistently proper stunning is likely to remain unachievable. Finally, the call to overcome inconsistent stun results by increasing current flow to levels that electrocute birds is investigated. Controversy surrounding the impact of electrocution on carcass quality and operator safety will continue to cause resistance to the adoption of this method of poultry slaughter. The conclusion offers four recommendations that follow from the cumulative results of these investigations. 相似文献
69.
Thi Binh Minh Nguyen A.T.M. Nurul Amin 《Environment, Development and Sustainability》2002,4(3):279-297
In recent years flows of foreign direct investment (FDI) to developing countries have rapidly been increasing. It is now an important contributor to the national economy and urban growth in scores of developing countries. Rapid urbanization in these countries is leading to many problems in the cities. Existing urban infrastructure and municipal services have been unable to cope with the increased demand arising from growing population and rapid economic growth. Consequently, the environment in these cities has deteriorated alarmingly. This paper assesses the role of FDI in urban environmental management (UEM) by analyzing the linkages between them for Hanoi City in Vietnam. The paper's analysis and findings are presented under three main themes: one, FDI, employment and income; two, FDI and environmental degradation; and three, potential of utilizing FDI for the provision of urban environmental infrastructure and services (UEI&S) in order to improve the urban environment. Both primary and secondary source data have been used. Policy implications of the research findings are drawn from the perspective of sustainable development. 相似文献
70.