全文获取类型
收费全文 | 3606篇 |
免费 | 74篇 |
国内免费 | 33篇 |
专业分类
安全科学 | 134篇 |
废物处理 | 102篇 |
环保管理 | 643篇 |
综合类 | 644篇 |
基础理论 | 928篇 |
环境理论 | 10篇 |
污染及防治 | 842篇 |
评价与监测 | 202篇 |
社会与环境 | 155篇 |
灾害及防治 | 53篇 |
出版年
2023年 | 15篇 |
2022年 | 18篇 |
2021年 | 40篇 |
2020年 | 23篇 |
2019年 | 33篇 |
2018年 | 84篇 |
2017年 | 78篇 |
2016年 | 92篇 |
2015年 | 90篇 |
2014年 | 97篇 |
2013年 | 253篇 |
2012年 | 166篇 |
2011年 | 215篇 |
2010年 | 157篇 |
2009年 | 174篇 |
2008年 | 184篇 |
2007年 | 217篇 |
2006年 | 218篇 |
2005年 | 154篇 |
2004年 | 109篇 |
2003年 | 102篇 |
2002年 | 123篇 |
2001年 | 69篇 |
2000年 | 63篇 |
1999年 | 59篇 |
1998年 | 53篇 |
1997年 | 65篇 |
1996年 | 46篇 |
1995年 | 55篇 |
1994年 | 51篇 |
1993年 | 31篇 |
1992年 | 35篇 |
1991年 | 26篇 |
1990年 | 23篇 |
1989年 | 15篇 |
1988年 | 16篇 |
1987年 | 17篇 |
1986年 | 20篇 |
1985年 | 20篇 |
1984年 | 24篇 |
1983年 | 24篇 |
1982年 | 22篇 |
1981年 | 18篇 |
1980年 | 19篇 |
1979年 | 20篇 |
1978年 | 15篇 |
1967年 | 14篇 |
1965年 | 14篇 |
1961年 | 12篇 |
1957年 | 14篇 |
排序方式: 共有3713条查询结果,搜索用时 15 毫秒
41.
A survey is given on fluid-dynamic effects caused by the structure and properties of biological surfaces. It is demonstrated
that the results of investigations aiming at technological applications can also provide insights into biophysical phenomena.
Techniques are described both for reducing wall shear stresses and for controlling boundary-layer separation. (a) Wall shear
stress reduction was investigated experimentally for various riblet surfaces including a shark skin replica. The latter consists
of 800 plastic model scales with compliant anchoring. Hairy surfaces are also considered, and surfaces in which the no-slip
condition is modified. Self-cleaning surfaces such as that of lotus leaves represent an interesting option to avoid fluid-dynamic
deterioration by the agglomeration of dirt. An example of technological implementation is discussed for riblets in long-range
commercial aircraft. (b) Separation control is also an important issue in biology. After a few brief comments on vortex generators,
the mechanism of separation control by bird feathers is described in detail. Self-activated movable flaps (=artificial bird
feathers) represent a high-lift system enhancing the maximum lift of airfoils by about 20%. This is achieved without perceivable
deleterious effects under cruise conditions. Finally, flight experiments on an aircraft with laminar wing and movable flaps
are presented. 相似文献
42.
Letter to the Editors 总被引:1,自引:0,他引:1
Peter H. Duesberg 《Die Naturwissenschaften》1990,77(3):97-102
43.
44.
45.
46.
47.
48.
49.
Alan B. Bolten Peter Feinsinger Herbert G. Baker Irene Baker 《Die Naturwissenschaften》1990,77(9):452-452
50.
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