全文获取类型
收费全文 | 983篇 |
免费 | 74篇 |
专业分类
1057篇 |
出版年
2019年 | 8篇 |
2018年 | 12篇 |
2017年 | 8篇 |
2016年 | 14篇 |
2015年 | 11篇 |
2014年 | 18篇 |
2013年 | 22篇 |
2012年 | 61篇 |
2011年 | 64篇 |
2010年 | 29篇 |
2009年 | 27篇 |
2008年 | 53篇 |
2007年 | 41篇 |
2006年 | 45篇 |
2005年 | 36篇 |
2004年 | 50篇 |
2003年 | 39篇 |
2002年 | 30篇 |
2001年 | 38篇 |
2000年 | 49篇 |
1999年 | 22篇 |
1998年 | 13篇 |
1997年 | 11篇 |
1996年 | 9篇 |
1995年 | 15篇 |
1994年 | 9篇 |
1993年 | 9篇 |
1992年 | 18篇 |
1991年 | 21篇 |
1990年 | 10篇 |
1989年 | 11篇 |
1988年 | 11篇 |
1987年 | 21篇 |
1986年 | 8篇 |
1985年 | 13篇 |
1984年 | 18篇 |
1983年 | 7篇 |
1982年 | 14篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1978年 | 6篇 |
1977年 | 9篇 |
1971年 | 7篇 |
1969年 | 5篇 |
1936年 | 18篇 |
1933年 | 13篇 |
1932年 | 8篇 |
1931年 | 11篇 |
1929年 | 4篇 |
排序方式: 共有1057条查询结果,搜索用时 15 毫秒
1.
2.
Background
Phylogenies capture the evolutionary ancestry linking extant species. Correlations and similarities among a set of species are mediated by and need to be understood in terms of the phylogenic tree. In a similar way it has been argued that biological networks also induce correlations among sets of interacting genes or their protein products. 相似文献3.
4.
5.
6.
M. L. Dini J. O'Donnell S. R. Carpenter M. M. Elser J. J. Elser A. M. Bergquist 《Hydrobiologia》1987,150(2):185-191
The timing and magnitude of diel migration in two daphnid assemblages were determined from a series of vertical profiles of daphnid size distribution. Animals were collected concurrently for gut fullness determination. Only large daphnids (> 1.4 mm) migrated, but these animals could account for substantial vertical and diel differences in phosphorus excretion rate. Gut fullness measurements and time courses of diel vertical migration suggested that large Daphnia can cause a net downward flux of phosphorus during summer in thermally stratified lakes. 相似文献
7.
A Vellodi J R Hobbs N M O'Donnell B S Coulter K Hugh-Jones 《BMJ (Clinical research ed.)》1987,295(6610):1375-1376
Allogenic bone marrow transplantation was carried out on a 3 year old girl with Niemann-Pick disease type B. Successful engraftment was achieved, and nine months after the procedure there was definite clearing of the sphingomyelin from the liver and pronounced clearing from the bone marrow. Any patient with Niemann-Pick disease type B complicated by early or severe hepatic impairment should be considered for bone marrow transplantation. 相似文献
8.
I J O'Donnell J K Dineen B M Wagland S Letho T A Dopheide W N Grant C W Ward 《International journal for parasitology》1989,19(7):793-802
The excretory-secretory products of exsheathed third-stage larvae of Trichostrongylus colubriformis conferred some protection to guinea pigs against homologous challenge. A glycoprotein with an apparent molecular mass of approximately 94 kDa was the dominant immunogen in post-exsheathment products. Immunoblots revealed IgG antibodies to this glycoprotein in sera from multiply-infected guinea pigs and some sheep, and in sera of guinea pigs after three truncated infections which had been restricted by anthelmintic treatments to development of the third parasitic stage. IgA antibodies to this protein were also found in intestinal lymph of a naturally infected sheep. Fluorescent antibody studies indicated that this 94 kDa component was associated with cells in the central body cavity of third-stage larvae, but was absent from fourth-stage larvae or adult worms. Fractionation and protection assays in guinea pigs revealed that while the native and aggregated 94 kDa protein conferred some host protection, it was not the only protective component of the excretory-secretory products of exsheathed third-stage larvae of T. colubriformis. 相似文献
9.
10.
V P Torchilin A L Klibanov L Huang S O'Donnell N D Nossiff B A Khaw 《FASEB journal》1992,6(9):2716-2719
The less than optimal accumulation of immunoliposome-associated reagents at target sites has often been attributed to the rapid in vivo clearance of immunoliposomes from the blood. In an attempt to overcome the drawback of rapid clearance and use the targeting potential of immunoliposomes, we have prepared long-circulating, 111In-labeled immunoliposomes. Targeting properties and enhanced circulation times were demonstrated in a rabbit model of acute experimental myocardial infarct. The specificity of liposomes for newly exposed intracellular cardiac myosin at the necrotic sites was achieved by incorporating monoclonal antimyosin antibody. Extended circulation times were achieved by cocoating the antimyosin-liposomes with polyethylene glycol (PEG). The half-life of the immunoliposomes was 40 min, which increased to 200 min with 4% mol PEG and to approximately 1000 min with 10% mol PEG. The degree of binding of modified immunoliposomes at the target sites was also dependent on the concentration of PEG incorporated at the liposome surface. This study demonstrates the accumulation of long-circulating targeted liposomes at the area of acute rabbit experimental myocardial infarction. 相似文献