全文获取类型
收费全文 | 23737篇 |
免费 | 250篇 |
国内免费 | 205篇 |
专业分类
安全科学 | 631篇 |
废物处理 | 1050篇 |
环保管理 | 2841篇 |
综合类 | 3509篇 |
基础理论 | 6548篇 |
环境理论 | 6篇 |
污染及防治 | 6319篇 |
评价与监测 | 1642篇 |
社会与环境 | 1513篇 |
灾害及防治 | 133篇 |
出版年
2022年 | 204篇 |
2021年 | 168篇 |
2020年 | 151篇 |
2019年 | 162篇 |
2018年 | 322篇 |
2017年 | 348篇 |
2016年 | 516篇 |
2015年 | 399篇 |
2014年 | 638篇 |
2013年 | 1838篇 |
2012年 | 751篇 |
2011年 | 1048篇 |
2010年 | 910篇 |
2009年 | 910篇 |
2008年 | 1052篇 |
2007年 | 1119篇 |
2006年 | 938篇 |
2005年 | 813篇 |
2004年 | 778篇 |
2003年 | 826篇 |
2002年 | 759篇 |
2001年 | 1052篇 |
2000年 | 753篇 |
1999年 | 421篇 |
1998年 | 289篇 |
1997年 | 319篇 |
1996年 | 325篇 |
1995年 | 369篇 |
1994年 | 335篇 |
1993年 | 265篇 |
1992年 | 293篇 |
1991年 | 276篇 |
1990年 | 305篇 |
1989年 | 294篇 |
1988年 | 230篇 |
1987年 | 234篇 |
1986年 | 210篇 |
1985年 | 232篇 |
1984年 | 225篇 |
1983年 | 218篇 |
1982年 | 196篇 |
1981年 | 181篇 |
1980年 | 163篇 |
1979年 | 184篇 |
1978年 | 137篇 |
1977年 | 158篇 |
1975年 | 133篇 |
1974年 | 133篇 |
1973年 | 136篇 |
1972年 | 122篇 |
排序方式: 共有10000条查询结果,搜索用时 828 毫秒
851.
852.
F. Monna F. van Oort P. Hubert J. Dominik J. Bolte J.-L. Loizeau J. Labanowski J. Lamri C. Petit G. Le Roux C. Chateau 《Journal of environmental radioactivity》2009
An 80-year soil archive, the 42-plot experimental design at the INRA in Versailles (France), is used here to study long-term contamination by 137Cs atmospheric deposition and the fate of this radioisotope when associated with various agricultural practices: fallow land, KCl, NH4(NO3), superphosphate fertilizers, horse manure and lime amendments. The pertinence of a simple box model, where radiocaesium is supposed to move downward by convectional mechanisms, is checked using samples from control plots which had been neither amended, nor cultivated since 1928. This simple model presents the advantage of depending on only two parameters: α, a proportional factor allowing the historical atmospheric 137Cs fluxes to be reconstructed locally, and k, an annual loss coefficient from the plow horizon. Another pseudo-unknown is however necessary to run the model: the shape of historical 137Cs deposition, but this function can be easily computed by merging several curves previously established by other surveys. A loss of ∼1.5% per year from the plow horizon, combined with appropriate fluxes, provides good concordance between simulated and measured values. In the 0–25 cm horizon, the residence half time is found to be ∼18 yr (including both migration and radioactive decay). Migration rate constants are also calculated for some plots receiving continuous long-term agricultural treatments. Comparison with the control plots reveals significant influence of amendments on 137Cs mobility in these soils developed from a unique genoform. 相似文献
853.
Specific ecogenetic features of solods in the forest-steppe zone has been studied, and the role of biotic and abiotic factors of soil formation has been estimated. Differentiation of soil horizons with respect to the physical clay fraction accounts for specific features of their moistening, which is reflected in the ratio of strongly and weakly crystallized forms of iron. Periodic changes in redox conditions results in iron segregation, and a high content of fulvic acids accounts for its eluvial migration. These processes are controlled by soil geochemical barriers. 相似文献
854.
855.
Use and knowledge of fuelwood in three rural caatinga (dryland) communities in NE Brazil 总被引:1,自引:0,他引:1
I. M. M. Sá e Silva L. C. Marangon N. Hanazaki U. P. Albuquerque 《Environment, Development and Sustainability》2009,11(4):833-851
The woody species known, used, and preferred as fuelwood were examined in three rural communities within the county of Soledade,
Paraíba State, NE Brazil. Ethnobotanical information was collected using semi-structured interviews with more than 90% of
the local households (55 adult residents; 31 women, and 24 males). The interviewees cited 36 plant species as fuelwoods, distributed
among 30 genera and 15 families, in addition to two unidentified plants. The plant families represented by the largest numbers
of species were Euphorbiaceae, Anacardiaceae, Mimosaceae, Caesalpiniaceae, Sapotaceae, and Fabaceae. The species Caesalpinia pyramidalis Tul. (“catingueira”) was cited with the greatest frequency in all three communities. Within the communities we found significant
differences on the number of plants cited and actually used (p < 0.05), indicating that the residents knew more fuelwood species than they effectively harvest. The different distances
from the communities to the urban centers were not related to differences on the use or the size of the stocks of fuelwood.
Additionally, the study revealed that the communities examined still maintain a significant knowledge of the use of energy-providing
plants in spite of the widespread use of liquefied petroleum gas (LPG).
Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue. 相似文献
856.
The placement of 1918 redwing nests has been analyzed, including 214 nests of 90 marked females (2–8 known nests per female). A high level of intraspecific and individual variation in utilization of different types of nest supports is described. It is shown that redwings choose nest sites without regard to previous experience (either positive or negative) or to the placement of their parent nest. Under conditions of the northern taiga, such behavior provides for significant reduction of chick mortality by the end of the season. This is con- firmed by comparison with the song thrush (T. philomelos), which nests mainly on spruce trees. 相似文献
857.
A. P. Gusev 《Russian Journal of Ecology》2009,40(3):160-165
Specific features of progressive succession in the vegetation of anthropogenically transformed landscapes in southeastern Belarus have been studied in permanent test plots. Using phytoindication scales proposed by Ellenberg (1974) and Tsyganov (1983), trends of changes in ecological conditions in the first years of succession have been revealed. 相似文献
858.
The paper is devoted to the phenomenon of methanogenic activity of woody debris, i.e., methane production in the course of wood decomposition by fungi, which are not directly involved in methane synthesis but form an initial link in the trophic chain leading to methanogenic archaea. Expert evaluation of probable amounts of methane emission is made. The results show that woody debris is an important global source of this greenhouse gas. 相似文献
859.
Landscape-geochemical features providing for manifestation of gigantism in herbaceous plants have been revealed in natural habitats in the south of Sakhalin and Kunashir islands. Tall herb assemblages have proved to be associated with geochemical landscapes characterized by reducing (gley or hydrogen sulfide) conditions and increased contents of petroleum hydrocarbons and some trace elements (total and movable forms). A hypothesis is put forward that gigantism in herbaceous plants is manifested in zones of active faults, which serve as a kind of conduits supplying endogenous heat, matter, and water to the root systems. 相似文献
860.
The results of studies on postfire succession in larch forests of the permafrost zone are discussed. The main directions of successional processes in burned-out areas of different ages are described. It has been shown that secondary pyrogenic successions in larch forests follow the scheme of rapid regeneration without tree species replacement and the model of succession tolerance. Groups of plant species with different life strategies and indicator species characterizing different stages of the overgrowing of burned-out areas have been identified. 相似文献