全文获取类型
收费全文 | 5898篇 |
免费 | 31篇 |
国内免费 | 25篇 |
专业分类
安全科学 | 141篇 |
废物处理 | 318篇 |
环保管理 | 522篇 |
综合类 | 884篇 |
基础理论 | 1443篇 |
环境理论 | 1篇 |
污染及防治 | 1477篇 |
评价与监测 | 417篇 |
社会与环境 | 722篇 |
灾害及防治 | 29篇 |
出版年
2023年 | 45篇 |
2022年 | 78篇 |
2021年 | 60篇 |
2020年 | 30篇 |
2019年 | 45篇 |
2018年 | 79篇 |
2017年 | 97篇 |
2016年 | 116篇 |
2015年 | 78篇 |
2014年 | 157篇 |
2013年 | 470篇 |
2012年 | 182篇 |
2011年 | 259篇 |
2010年 | 229篇 |
2009年 | 236篇 |
2008年 | 276篇 |
2007年 | 283篇 |
2006年 | 265篇 |
2005年 | 225篇 |
2004年 | 201篇 |
2003年 | 225篇 |
2002年 | 193篇 |
2001年 | 265篇 |
2000年 | 167篇 |
1999年 | 107篇 |
1998年 | 48篇 |
1997年 | 65篇 |
1996年 | 59篇 |
1995年 | 66篇 |
1994年 | 73篇 |
1993年 | 62篇 |
1992年 | 64篇 |
1991年 | 64篇 |
1990年 | 72篇 |
1989年 | 53篇 |
1988年 | 58篇 |
1987年 | 56篇 |
1986年 | 58篇 |
1985年 | 45篇 |
1984年 | 50篇 |
1983年 | 48篇 |
1982年 | 54篇 |
1980年 | 34篇 |
1979年 | 36篇 |
1978年 | 30篇 |
1977年 | 30篇 |
1976年 | 29篇 |
1974年 | 33篇 |
1973年 | 31篇 |
1972年 | 28篇 |
排序方式: 共有5954条查询结果,搜索用时 31 毫秒
11.
Four introduced and one aboriginal species of the genus Pinus L. have been studied in the middle taiga subzone of southern Karelia. Significant interspecific differences in the dates of onset, cessation, and peak of the growth of shoots and needles have been revealed. It has been shown that their annual increment depends on the rate of growth, rather than on its duration. The dynamics of shoot and needle growth in introduced and aboriginal species, though largely similar, differ in some respects. These differences reflect species-specific responses to hydrothermal conditions in a certain growing season. 相似文献
12.
13.
In the diurnal lepidopteran fauna of the northern taiga subzone in the western Russian Plain, the species inhabiting primary biotopic complexes typical of this subzone currently account for slightly more than 60% of the total species richness and abundance. A large part of the fauna is represented by the species of more southern origin, whose expansion to the northern taiga was caused by anthropogenic transformation of landscapes between the 12th and 20th centuries and recent climate warming. 相似文献
14.
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
15.
V. I. Kolmakov N. A. Gaevskii E. A. Ivanova O. P. Dubovskaya I. V. Gribovskaya E. S. Kravchuk 《Russian Journal of Ecology》2002,33(2):97-103
In the periods of summer and autumn bloom of the Stephanodiscus hantzschii Crun. in recreational water bodies, studies on the vertical distribution of chlorophyll a, its contents per unit biomass, efficiency in using photosynthetically active radiation (EPhAR), and assimilative activity of microalgae were performed. The results confirmed the existence of two ecophysiological forms of St. hantzschii and provided evidence that both forms are typically autotrophic and can efficiently use low-intensity PhAR for photosynthesis. 相似文献
16.
When combined in the lining and covering of waste-containment facilities, soil and geosynthetic components protect the environment by acting as a hydraulic barrier. Equipment loading may significantly increase the tensile stress induced in geosynthetic components, leading to a potential stability problem. Large equipment loadings may also result in a localized circular slip surface during construction operations. New analytical method based on discrete element modelling is proposed for estimating the distribution of tensile force developed in the individual geosynthetic components of the lining system and for evaluating the safety factor of slope failure due to equipment loading. The analytical results of an example are presented to demonstrate the applicability of the analytical method for the lining system of a waste landfill. The analyses of the example show that equipment loading provide a substantial increase in the tensile forces of the geosynthetic components of a lining system and that the possibility of shallow failure due to equipment loading increases as the slope becomes steeper. This method is a useful tool for analysing the lining system of waste landfills with complex lining components. 相似文献
17.
Indices of abundance and reproduction rate are considered in some groups of aquatic and terrestrial vertebrates from the zones of technogenic disasters. Upon a critical population decline caused by external destructive factors, such as emissions of acute ecotoxicants, the ecophysiological and behavioral compensatory mechanisms are activated, which provide for restoration of the total population size to the optimum within a short period of time. Environmental pollution with substances disturbing the reproductive function has the gravest consequences for animals. In this case, population size may remain fairly high, and, therefore, the effect of enhanced reproduction as a response to population decline does not take place, which eventually leads to a gradual but irreversible destruction of the population. Pathologies of reproduction should be used as a criterion for assessing the state of animals in the zones of technogenic disasters.Translated from Ekologiya, No. 1, 2005, pp. 32–38.Original Russian Text Copyright © 2005 by Shilova, Shatunovskii. 相似文献
18.
19.
In the past 20 years a variety of indices have been suggested for measuring the severity of trauma, however none of them meets the requirement of being a simple and objective instrument that can be utilized efficiently by lay persons and providers of health services without previous experience in triaging. A new system has been proposed which meets this requirement and which has been validated with 197 injured persons at the emergency ward of the Valle University Hospital in Call, Colombia. The instrument showed a high level of concordance with the conventional triaging method and classifies victims into four categories: critical with recovery unlikely, critical but recoverable, moderately serious, and ambulatory. There is discussion on the reliability of this instrument and it is recommended that it be validated with victims from larger disasters. Regardless, it has the advantage of being specific and free of the subjectivity that characterizes other indices. 相似文献
20.
A study was undertaken to establish the role of free amino acids (FAA) in aerobic energy dissipation in embryos of turbot (Scophthalmus maximus) which contain an oil globule in the egg. Laboratory-reared developing eggs and larvae (15°C, 34 salinity) were measured for oxygen uptake, ammonia excretion, contents of FAA, protein, and ammonium, and volumes of yolksac and oil globule. Newly spawned eggs from different batches contained 55 to 90 nmol egg–1 of FAA. Resorption of FAA occurred in parallel with the consumption of yolk. Resorption of the oil globule, however, occurred predominantly after hatching and mainly after yolk resorption. The combined data suggest that approximately 70% of the FAA are utilized as an energy substrate, while the rest are polymerized into body proteins. FAA become a significant energy substrate in the early egg stage and account for 100% of the aerobic energy dissipation 2 d after Fertilization then decrease to ca. 60% at the time of hatching. Lipids derived from the oil globule seem to be the main fuel after hatching and account for ca. 90% of the energy dissipation at the onset of first-feeding. Thus, the energetics of fish embryos which contain an oil globule seems to be different from those that depend exclusively on the nutritional reserves of the yolk. 相似文献