全文获取类型
收费全文 | 35196篇 |
免费 | 398篇 |
国内免费 | 477篇 |
专业分类
安全科学 | 1096篇 |
废物处理 | 1710篇 |
环保管理 | 4602篇 |
综合类 | 5479篇 |
基础理论 | 9175篇 |
环境理论 | 8篇 |
污染及防治 | 8679篇 |
评价与监测 | 2531篇 |
社会与环境 | 2570篇 |
灾害及防治 | 221篇 |
出版年
2023年 | 170篇 |
2022年 | 359篇 |
2021年 | 392篇 |
2020年 | 242篇 |
2019年 | 321篇 |
2018年 | 529篇 |
2017年 | 568篇 |
2016年 | 857篇 |
2015年 | 648篇 |
2014年 | 1011篇 |
2013年 | 2939篇 |
2012年 | 1198篇 |
2011年 | 1609篇 |
2010年 | 1300篇 |
2009年 | 1359篇 |
2008年 | 1652篇 |
2007年 | 1579篇 |
2006年 | 1417篇 |
2005年 | 1256篇 |
2004年 | 1222篇 |
2003年 | 1170篇 |
2002年 | 1110篇 |
2001年 | 1325篇 |
2000年 | 924篇 |
1999年 | 562篇 |
1998年 | 421篇 |
1997年 | 445篇 |
1996年 | 479篇 |
1995年 | 552篇 |
1994年 | 460篇 |
1993年 | 406篇 |
1992年 | 439篇 |
1991年 | 419篇 |
1990年 | 385篇 |
1989年 | 374篇 |
1988年 | 341篇 |
1987年 | 293篇 |
1986年 | 284篇 |
1985年 | 297篇 |
1984年 | 314篇 |
1983年 | 302篇 |
1982年 | 312篇 |
1981年 | 266篇 |
1980年 | 204篇 |
1979年 | 220篇 |
1978年 | 188篇 |
1977年 | 161篇 |
1975年 | 165篇 |
1973年 | 198篇 |
1972年 | 183篇 |
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
71.
72.
Long-term stationary studies on the ecology of the northern mole vole (Ellobius talpinus Pall.), performed by the mark–recapture method from 1985 to 1997, have provided original data on population dynamics and structure. The analysis shows that, to reveal cyclic fluctuations of population size in this species, the period of three years should be taken as a unit of time for estimating the duration of one phase. The 12-year population cycle in E. talpinus has four distinct phases: an increase, a peak, a decline, and a minimum. At each phase, the population is characterized by certain features of family structure, age composition, birth and death rates, and the composition of migrants. 相似文献
73.
We present a case of ultrasonographic prenatal diagnosis at 24 weeks of femur—fibula—ulna (FFU) complex. To our knowledge, this is the first report of an early prenatal diagnosis of FFU. 相似文献
74.
75.
Observations of air temperature changes in a steppe marmot burrow were performed from late July to mid-October. Until early September, temperature in the burrow remained relatively constant, but then it began to decrease rapidly. This occurred after air temperature above the ground became equal to the temperature in the burrow. Supposedly, it is in this particular period that marmots begin to plug the entrance to the burrow with earth, thus reducing heat exchange between the increasingly cold aboveground air and the air in the burrow. 相似文献
76.
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
77.
78.
Methodological Basis of Ecological Safety Standards for the Technogenic Impact of Mineral Resource Exploitation 总被引:1,自引:0,他引:1
A new methodological approach to the development of biological and technological safety standards for the impact of underground mining on the natural biota is proposed. 相似文献
79.
N. P. Kosykh N. P. Mironycheva-Tokareva A. M. Peregon E. K. Parshina 《Russian Journal of Ecology》2008,39(7):466-474
New experimental data on biological productivity of plant communities in oligotrophic and mesotrophic bogs of the middle taiga
subzone over the past five years are presented. The relationship between net primary production and the stock of live phytomass
is estimated. The stock of necromass in oligotrophic bog ecosystems increases from west to east, while the stock of live phytomass
and net primary production decrease. 相似文献
80.
N. O. Kin 《Russian Journal of Ecology》2008,39(4):254-260
Heavy metal accumulation by plant communities has been studied in different zones of impact of gas field development. The contents of heavy metals in different blocks of plant communities has proved to depend not only on the location of phytocenosis but also on its species composition. Communities dominated by species of the family Poaceae contain smaller amounts of heavy metals than those dominated by species of the family Asteraceae, especially of the genus Artemisia. The order of precedence in the accumulation of heavy metals in different blocks of plant communities has been revealed. 相似文献