全文获取类型
收费全文 | 1701篇 |
免费 | 5篇 |
专业分类
电工技术 | 3篇 |
综合类 | 52篇 |
化学工业 | 51篇 |
金属工艺 | 2篇 |
机械仪表 | 1篇 |
建筑科学 | 57篇 |
轻工业 | 20篇 |
水利工程 | 2篇 |
无线电 | 6篇 |
一般工业技术 | 27篇 |
冶金工业 | 1455篇 |
自动化技术 | 30篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2019年 | 3篇 |
2018年 | 9篇 |
2017年 | 3篇 |
2015年 | 11篇 |
2014年 | 20篇 |
2013年 | 18篇 |
2012年 | 18篇 |
2011年 | 19篇 |
2010年 | 17篇 |
2009年 | 14篇 |
2008年 | 16篇 |
2007年 | 12篇 |
2006年 | 6篇 |
2005年 | 3篇 |
2004年 | 15篇 |
2003年 | 11篇 |
2002年 | 3篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 39篇 |
1998年 | 404篇 |
1997年 | 248篇 |
1996年 | 155篇 |
1995年 | 105篇 |
1994年 | 88篇 |
1993年 | 94篇 |
1992年 | 14篇 |
1991年 | 28篇 |
1990年 | 32篇 |
1989年 | 31篇 |
1988年 | 25篇 |
1987年 | 31篇 |
1986年 | 19篇 |
1985年 | 16篇 |
1984年 | 4篇 |
1983年 | 8篇 |
1982年 | 10篇 |
1981年 | 8篇 |
1980年 | 8篇 |
1978年 | 5篇 |
1977年 | 32篇 |
1976年 | 83篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1965年 | 1篇 |
1963年 | 1篇 |
1960年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有1706条查询结果,搜索用时 0 毫秒
991.
992.
Artificial selection was used to establish different levels of agonistic behavior in laboratory-reared wild female Mus musculus. A within-family selection design with replicated high and low lines and two nonselected control lines was employed. Females only were tested at 8 weeks of age on 2 consecutive days. Testing consisted of placing a C57BL/6 female mouse in the home cage of the isolation-reared wild mouse for 7 min or until an attack occurred. The wild females were rated on a 5-point scale for agonistic behavior, and the sum of the scores over the 2 test days was the criterion for selection. The six lines, each containing ten breeding pairs, were selected for four generations. By the fourth selected generation, the responses of the high and low lines had diverged in the expected directions. One-way analyses of variance indicated reliable differences among high, low, and control lines in the second, third, and fourth generations. It was concluded that female agonistic behavior is influenced by genotype and that the level of this behavior can be manipulated by means of artificial selection. 相似文献
993.
994.
995.
996.
A very simple, physical calculation of the magnitude of the response of a single buried conducting drum to electromagnetic induction searching is given 相似文献
997.
998.
999.
Gastric varices may appear in association with esophageal varices secondary to portal-hypertension or as an independent manifestation of splenic vein obstruction. Since gastric varices often manifest as radiologic filling defects in the gastric fundus or cardia, differentiation from tumors and many other diseases becomes imperative. Unfortunately, routine diagnostic pprocedures may be of limited value. The difficulties in the diagnosis of gastric varices are illustrated with three specific cases. Correct diagnosis is best established with the aid of endoscopy and such special procedures as celiac angiography or splenoportography. With the help of three cases, the characteristics of gastric varices are reviewed and their evaluation and management are outlined. 相似文献
1000.