全文获取类型
收费全文 | 419944篇 |
免费 | 43658篇 |
国内免费 | 196篇 |
专业分类
463798篇 |
出版年
2016年 | 4515篇 |
2015年 | 5949篇 |
2014年 | 7052篇 |
2013年 | 10619篇 |
2012年 | 11481篇 |
2011年 | 11960篇 |
2010年 | 8143篇 |
2009年 | 7473篇 |
2008年 | 10683篇 |
2007年 | 11334篇 |
2006年 | 10672篇 |
2005年 | 10151篇 |
2004年 | 10248篇 |
2003年 | 10013篇 |
2002年 | 9815篇 |
2001年 | 17346篇 |
2000年 | 17390篇 |
1999年 | 14051篇 |
1998年 | 4977篇 |
1997年 | 5286篇 |
1996年 | 5011篇 |
1995年 | 4727篇 |
1994年 | 4632篇 |
1993年 | 4629篇 |
1992年 | 12266篇 |
1991年 | 12071篇 |
1990年 | 12083篇 |
1989年 | 11856篇 |
1988年 | 11165篇 |
1987年 | 10500篇 |
1986年 | 9819篇 |
1985年 | 10238篇 |
1984年 | 8439篇 |
1983年 | 7275篇 |
1982年 | 5613篇 |
1981年 | 5020篇 |
1980年 | 4694篇 |
1979年 | 8082篇 |
1978年 | 6300篇 |
1977年 | 5940篇 |
1976年 | 5672篇 |
1975年 | 6130篇 |
1974年 | 6697篇 |
1973年 | 6568篇 |
1972年 | 6122篇 |
1971年 | 5535篇 |
1970年 | 4767篇 |
1969年 | 4782篇 |
1968年 | 4453篇 |
1967年 | 3808篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
111.
112.
113.
114.
115.
116.
117.
E Giannazzo F Licata G Li Volsi G Mio F Santangelo M Scivoli 《Bollettino della Società italiana di biologia sperimentale》1992,68(11):677-683
A computer-assisted analysis of the spatial distribution of neurons having homogeneous characteristics is described in this paper. The camera lucida drawings of sections of a brain nucleus and the points representing the neurons labeled on the basis of a specific behavior of discharge rates were digitized on a personal computer Amiga 2000 or IBM compatible. Our software provided: a) the computerized, stereotaxically oriented reconstruction of the stored sections and of the plotted neurons; b) the identification within each section of the mass center (MC) of the units sharing a given behavior and of the area where the density of such neurons was maximal (MDA). The routine was tested on the spatial distribution of neuronal responses to serotonin in the lateral vestibular nucleus. 相似文献
118.
G. Rai M. Stamenkovi-Radak T. Savi M. Andjelkovi 《Journal of Zoological Systematics and Evolutionary Research》2008,46(1):31-37
The adaptive significance of inversion polymorphism of Drosophila subobscura is well established. However, little is known about gene combinations within inversions which are coadapted because of population-specific effects. We studied this aspect of Dobzhansky's coadaptation hypothesis, using the systematic inbreeding method. Differences in magnitude and quality of inversion polymorphism in two ecologically and topologically distinct habitats were compared after several generations of continuous full-sib inbreeding. Populations from the two habitats differ in frequency of homokaryotypes after third and fifth generation of inbreeding and in the levels of homozygosity of different gene arrangements. The effect of homozygosity appears population and chromosome specific. 相似文献
119.
N. I. Koshoridze N. G. Aleksidze N. B. Surguladze 《Journal of Evolutionary Biochemistry and Physiology》2003,39(4):446-450
Galactose- and inositol-binding proteins with lectin activity (GL-GAL and GL-I, respectively) were isolated from membranes enriched with cells of chicken brain fractions. Both lectins are glycoproteins of molecular mass 13.5 and 11.5 kDa, respectively; they show a high affinity to EDTA (GL-I) and EGTA (GL-GAL, GL-I), which indicates an important role of Ca+2 in molecular organization of these lectins. In brain glial cells of chick embryos, unlike adult chickens, a soluble form of lectins has been revealed; it is easily extracted with 2 mM EDTA and shows sensitivity to L-lactose, D-galactose, and N-acetyl-D-galactosamine. It is suggested that in the course of embryonal and postembryonal development of the chicken brain, a transformation and qualitative changes of the lectin spectrum occur due to a change of function of glial cells. 相似文献
120.
Numerous animal model studies of diabetes mellitus have been reported. Diabetes-induced vascular damage is a common cause of systemic organ damage in humans and animals. Many investigations have been made of human and animal offspring of diabetic mothers. The present report documents the sequential glomerular basement membrane (GBM) thickness in fetuses and infants of diabetic rats. The postnatal increase in GBM thickness was similar in the offspring of control and diabetic rats, and was not related to the sucrose concentration in the diet. 相似文献