全文获取类型
收费全文 | 284598篇 |
免费 | 30885篇 |
国内免费 | 1080篇 |
专业分类
316563篇 |
出版年
2018年 | 2684篇 |
2016年 | 3475篇 |
2015年 | 4859篇 |
2014年 | 5498篇 |
2013年 | 8054篇 |
2012年 | 8758篇 |
2011年 | 8898篇 |
2010年 | 5872篇 |
2009年 | 5384篇 |
2008年 | 7816篇 |
2007年 | 7879篇 |
2006年 | 7463篇 |
2005年 | 7164篇 |
2004年 | 7020篇 |
2003年 | 6768篇 |
2002年 | 6534篇 |
2001年 | 11846篇 |
2000年 | 11887篇 |
1999年 | 9426篇 |
1998年 | 3471篇 |
1997年 | 3704篇 |
1996年 | 3573篇 |
1995年 | 3181篇 |
1994年 | 3179篇 |
1993年 | 3137篇 |
1992年 | 7902篇 |
1991年 | 7880篇 |
1990年 | 7538篇 |
1989年 | 7504篇 |
1988年 | 6866篇 |
1987年 | 6615篇 |
1986年 | 6030篇 |
1985年 | 6226篇 |
1984年 | 5152篇 |
1983年 | 4346篇 |
1982年 | 3379篇 |
1981年 | 3145篇 |
1980年 | 2948篇 |
1979年 | 4954篇 |
1978年 | 3813篇 |
1977年 | 3724篇 |
1976年 | 3432篇 |
1975年 | 3786篇 |
1974年 | 4175篇 |
1973年 | 4092篇 |
1972年 | 3666篇 |
1971年 | 3435篇 |
1970年 | 3086篇 |
1969年 | 2995篇 |
1968年 | 2745篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
921.
922.
The evolution of the liver's glycogenic content, cytochemical characterization of the glycogen and glucose-6-phosphatase activity enable us to define three successive phases up to stage 36, just before the first feed. The grade which was low up to stage 24 is then due to beta-particles of ovule origin. Then, up to stage 27, there is a storage phase: alpha-particles appear and accumulate while the enzymatic activity remains non-existent. From the stage 28 to 36 the grade is progressively increasing, the enzymatic activity appears and increases. When the phase ends the liver is able to ensure glycemic regulation and to deal with exogenous nutritional contributions. 相似文献
923.
924.
phi6 bacteriophage from Pseudomonas phaseolicola has a pleomorphic shape due to an outer layer of lipid. This layer was removed with organic solvents or sodium dodecyl sulfate revealing a 50-nm cubic particle. The virus was found only in the central portion of the cell and not near the cell wall. 相似文献
925.
926.
J Daigneault G Aubin F Simard M De Braekeleer 《Human biology; an international record of research》1992,64(1):115-119
The incidence of cystic fibrosis (CF) in Saguenay-Lac-St.-Jean, a geographically isolated region of Quebec, was estimated to be 1 in 902 during the period 1975-1988. The carrier rate was calculated to be 1 in 15 inhabitants. The high incidence of CF in Saguenay-Lac-St.-Jean is probably the result of a founder effect and genetic drift for one or more mutations. Historical, demographic, and social factors also may have contributed to the high incidence. 相似文献
927.
928.
Donal F. Early 《BMJ (Clinical research ed.)》1973,3(5878):491-494
A housing association for the rehabilitation of adults suffering from psychiatric illness now has six council houses, a former private hotel, and two large houses—providing a total of 100 places. The cost of full board and lodging is about £6·00 a week; the association shows a small profit; and virtually all the residents are in open or sheltered work. 相似文献
929.
930.