全文获取类型
收费全文 | 135937篇 |
免费 | 7803篇 |
国内免费 | 72篇 |
专业分类
林业 | 5592篇 |
农学 | 4662篇 |
基础科学 | 867篇 |
17577篇 | |
综合类 | 18991篇 |
农作物 | 5123篇 |
水产渔业 | 7107篇 |
畜牧兽医 | 73026篇 |
园艺 | 1807篇 |
植物保护 | 9060篇 |
出版年
2020年 | 1188篇 |
2019年 | 1432篇 |
2018年 | 2262篇 |
2017年 | 2515篇 |
2016年 | 2312篇 |
2015年 | 2009篇 |
2014年 | 2462篇 |
2013年 | 5773篇 |
2012年 | 4372篇 |
2011年 | 5179篇 |
2010年 | 3509篇 |
2009年 | 3553篇 |
2008年 | 5158篇 |
2007年 | 4974篇 |
2006年 | 4643篇 |
2005年 | 4268篇 |
2004年 | 4114篇 |
2003年 | 4176篇 |
2002年 | 3809篇 |
2001年 | 4774篇 |
2000年 | 4642篇 |
1999年 | 3747篇 |
1998年 | 1473篇 |
1997年 | 1453篇 |
1996年 | 1342篇 |
1995年 | 1600篇 |
1994年 | 1328篇 |
1993年 | 1361篇 |
1992年 | 2763篇 |
1991年 | 2904篇 |
1990年 | 2868篇 |
1989年 | 2899篇 |
1988年 | 2610篇 |
1987年 | 2594篇 |
1986年 | 2544篇 |
1985年 | 2402篇 |
1984年 | 1959篇 |
1983年 | 1715篇 |
1982年 | 1155篇 |
1979年 | 1649篇 |
1978年 | 1285篇 |
1977年 | 1135篇 |
1976年 | 1100篇 |
1975年 | 1166篇 |
1974年 | 1358篇 |
1973年 | 1448篇 |
1972年 | 1378篇 |
1971年 | 1195篇 |
1970年 | 1247篇 |
1969年 | 1146篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
141.
M Stettner 《DTW. Deutsche tier?rztliche Wochenschrift》1990,97(4):171-174
1. The meaning of the terms bestiality and sadism is determined and each term is defined. 2. Officially known cases are analyzed as well as commented on with respect to the abused animal species, the different practices used, and the social background of the sodomites. 3. Since the 1st penal reform law of June 25, 1969 has come into force the section 175 b StGB (Penal Code) was canceled without substitution, and bestiality is no longer liable to prosecution. The Law of the Protection of Animals of August 18, 1986 does not explicitly mention bestiality. The application of the fixed penality code of the above mentioned Law of the Protection of Animals is discussed in the case of "merely" bestial or sadistic practices. 4. Finally the legal situation in most of the EEC member states as well as in some third-party countries is described and partially commented on. 相似文献
142.
143.
Recently compiled data on the state of stress have been used to define stress provinces in the conterminous United States in which the orientation and relative magnitude of the horizontal principal stresses are fairly uniform. The observed pattems of stress constrain mechanisms for generating intraplate lithospheric stresses. Coupled with new information on geologic structure and tectonism in seismically active areas of the Midcontinent and East, these data help to define some characteristics common to these areas and to identify key questions regarding why certain faults seem to be seismically active. 相似文献
144.
145.
146.
147.
148.
The effects of canopy cover, seeding depth, and soil moisture on emergence of Centaurea maculosa Lam. and C. diffusa Lam. were studied. Canopy cover had no effect on ermergence rate (seedlings/day/100 seeds) of either species. Seeds of both species emerged faster when placed on the soil surface. Emergence rate decreased as seeding depth increased. Both species required more than 55% initial soil moisture to initiate emergence, with 65–70% being optimum. Percentage emergence followed exactly the same trend as emergence rate. C. maculosa had better emergence characteristics over a wider range of conditions than C. diffusa, possibly being some of the reasons for the former having a wider geographical distribution in the United States and Canada. 相似文献
149.
Stuiver M 《Science (New York, N.Y.)》1978,202(4372):1109
150.