全文获取类型
收费全文 | 4494篇 |
免费 | 77篇 |
国内免费 | 43篇 |
专业分类
安全科学 | 170篇 |
废物处理 | 145篇 |
环保管理 | 722篇 |
综合类 | 762篇 |
基础理论 | 1187篇 |
环境理论 | 11篇 |
污染及防治 | 1074篇 |
评价与监测 | 284篇 |
社会与环境 | 206篇 |
灾害及防治 | 53篇 |
出版年
2023年 | 24篇 |
2022年 | 36篇 |
2021年 | 61篇 |
2020年 | 37篇 |
2019年 | 43篇 |
2018年 | 102篇 |
2017年 | 120篇 |
2016年 | 127篇 |
2015年 | 117篇 |
2014年 | 123篇 |
2013年 | 305篇 |
2012年 | 207篇 |
2011年 | 278篇 |
2010年 | 195篇 |
2009年 | 208篇 |
2008年 | 240篇 |
2007年 | 271篇 |
2006年 | 255篇 |
2005年 | 175篇 |
2004年 | 145篇 |
2003年 | 148篇 |
2002年 | 152篇 |
2001年 | 91篇 |
2000年 | 92篇 |
1999年 | 65篇 |
1998年 | 56篇 |
1997年 | 71篇 |
1996年 | 57篇 |
1995年 | 73篇 |
1994年 | 58篇 |
1993年 | 44篇 |
1992年 | 43篇 |
1991年 | 32篇 |
1990年 | 29篇 |
1989年 | 20篇 |
1988年 | 25篇 |
1987年 | 22篇 |
1986年 | 27篇 |
1985年 | 24篇 |
1984年 | 35篇 |
1983年 | 26篇 |
1982年 | 26篇 |
1981年 | 26篇 |
1980年 | 27篇 |
1979年 | 37篇 |
1978年 | 22篇 |
1977年 | 24篇 |
1976年 | 15篇 |
1975年 | 13篇 |
1957年 | 11篇 |
排序方式: 共有4614条查询结果,搜索用时 421 毫秒
61.
62.
63.
64.
65.
66.
A protocol for easy storage and later expansion of lymphocyte populations is given. Compared with methods using transformed cell lines, the method has a number of advantages for repeated production of cells for the isolation of DNA in amounts sufficient for use in diagnostic DNA technology. 相似文献
67.
Alan B. Bolten Peter Feinsinger Herbert G. Baker Irene Baker 《Die Naturwissenschaften》1990,77(9):452-452
68.
Frans J. Los MD PhD Diane Van Opstal Martin P. Schol Johannes L. J. Gaillard Helen Brandenburg Ans M. W. Van Den Ouweland Peter A. In 'T Veld 《黑龙江环境通报》1995,15(12):1155-1159
A prenatally detected case of a rare mosaic tetrasomy 12p/trisomy 12p is reported, presenting as the well-known accessory isochromosome 12p and a supernumerary single 12p marker in 17/24 and 6/24 clones of cultured amniotic fluid cells, respectively. The chromosomal nature of both marker chromosomes was investigated in cultured amniotic fluid cells by fluorescent in situ hybridization with various probes: the 12-centromeric probes pa12H8 and D12Z3, a whole chromosome 12 paint, and the chromosome 12p-specific paint M28. DNA analysis revealed a maternal origin of the extra 12p material. After counselling, the parents requested termination of pregnancy. Inspection and autopsy of the fetus revealed many of the dysmorphisms and internal structural abnormalities of the Pallister–Killian syndrome. 相似文献
69.
Baisen Zhang Ian Valentine Peter D. Kemp 《Agriculture, ecosystems & environment》2005,110(3-4):279-288
Decision tree, one of the data mining approaches, was used to model the relative abundance of five functional groups of plant species, namely high fertility response grasses (HFRG), low fertility tolerance grasses (LFTG), legume, moss and flatweeds in a New Zealand hill-pasture ecosystem using aboveground biomass. The model outputs were integrated with a geographic information system (GIS) to map and validate the predictions on a pasture. The decision tree models clearly revealed the interactions between the functional groups and environmental and management factors, and also indicated the relative importance of these factors in influencing the functional group abundance. Soil Olsen P was the most significant factor influencing the abundance of LFTG and moss, while soil bulk density, slope and annual P fertiliser input were the most significant factors influencing the abundance of legume, HFRG and flatweeds, respectively. Generally, slope and soil Olsen P were the two key factors underlying the patterns of abundance for these five functional groups. For the five functional groups studied, there was an overall predictive accuracy of 75%. Modelling functional group abundance simplified the investigation of the complex interrelationship between species and environment in a pasture ecosystem. The integration of the decision tree with GIS in this study provides a platform to investigate community structure and functional composition for a pasture over space, and thus can be applied as a tool in pasture management. 相似文献
70.
讨论了精密模锻件的分类密集形状的锻件、盘形锻件和长杆形锻件 ,以及精密模锻件的设计要点精密模锻件的机械加工余量、尺寸精度和表面粗糙度、分模面的选择、模锻斜度、圆角半径、肋的设计和腹板厚度的设计 相似文献