全文获取类型
收费全文 | 3898篇 |
免费 | 493篇 |
国内免费 | 4篇 |
专业分类
4395篇 |
出版年
2021年 | 35篇 |
2019年 | 36篇 |
2017年 | 37篇 |
2016年 | 63篇 |
2015年 | 89篇 |
2014年 | 106篇 |
2013年 | 167篇 |
2012年 | 191篇 |
2011年 | 189篇 |
2010年 | 107篇 |
2009年 | 99篇 |
2008年 | 179篇 |
2007年 | 152篇 |
2006年 | 141篇 |
2005年 | 145篇 |
2004年 | 145篇 |
2003年 | 105篇 |
2002年 | 131篇 |
2001年 | 114篇 |
2000年 | 120篇 |
1999年 | 93篇 |
1998年 | 46篇 |
1997年 | 51篇 |
1996年 | 47篇 |
1995年 | 47篇 |
1994年 | 45篇 |
1993年 | 41篇 |
1992年 | 91篇 |
1991年 | 76篇 |
1990年 | 61篇 |
1989年 | 73篇 |
1988年 | 101篇 |
1987年 | 80篇 |
1986年 | 65篇 |
1985年 | 105篇 |
1984年 | 81篇 |
1983年 | 72篇 |
1982年 | 47篇 |
1981年 | 40篇 |
1980年 | 33篇 |
1979年 | 54篇 |
1978年 | 62篇 |
1977年 | 36篇 |
1976年 | 39篇 |
1975年 | 43篇 |
1974年 | 42篇 |
1973年 | 51篇 |
1972年 | 35篇 |
1971年 | 44篇 |
1969年 | 39篇 |
排序方式: 共有4395条查询结果,搜索用时 15 毫秒
1.
C Chong-Cerrillo M E Selsted E M Peterson L M de la Maza 《The journal of peptide research》2003,61(5):237-242
Four antimicrobial peptides, protegrin-1, RTD-1, cryptdin-4, and indolicidin, were tested for their ability to inhibit the in vitro growth of Chlamydia trachomatis serovars E, L2, and mouse pneumonitis (MoPn). In general, protegrin-1 was found to have the strongest anti-chlamydial activity. Overall, of the three serovars tested, L2 was the most susceptible while MoPn was the most resistant to these peptides. 相似文献
2.
M C Peterson 《The Western journal of medicine》1994,161(2):148
Campylobacter jejuni is an almost ubiquitous, microaerophilic, gram-negative rod. Outbreaks have been associated with drinking raw milk or contaminated water and eating poultry. Campylobacter jejuni accounts for 3.2% to 6.1% of cases of diarrheal illness in the general population of the United States, and infected patients frequently present with abdominal pain and fever. Less frequently, C jejuni is responsible for bacteremia, septic arthritis, septic abortion, and other extraintestinal infections. Reactive arthritis, Reiter''s syndrome, the Guillain-Barré syndrome, and pancreatitis may accompany or follow C jejuni enterocolitis. Campylobacter jejuni is an important cause of diarrheal illness and is a more commonly identified stool organism than Salmonella or Shigella species. Recurrent and chronic infection is generally reported in immunocompromised hosts. 相似文献
3.
4.
5.
6.
Class II genes of the human major histocompatibility complex. The DO beta gene is a divergent member of the class II beta gene family 总被引:14,自引:0,他引:14
A novel class II beta chain gene is described. This gene, tentatively called DO beta, displays considerably less polymorphism than beta genes of the DP, DQ, and DR loci. The nucleotide sequence of the DO beta gene is strikingly similar to that of the previously identified murine A beta 2 gene. The DO beta gene displays the same exon/intron organization as other beta genes although the fifth exon and the translated portion of the sixth exon are longer than in other genes. A striking feature of the amino acid sequence deduced from the DO beta gene sequence is the pronounced hydrophobicity of the NH2-terminal region. This feature distinguishes the putative DO beta chain from other class II beta chains and raises the possibility that DO beta chains may interact with an alpha chain that is structurally different from those of the DP, DQ, and DR loci. It further suggests that the putative DO molecule may have a function different from those of other class II antigens. 相似文献
7.
Cholera toxin (CT) stimulated phospholipase activity and caused [3H]arachidonic acid (3H-AA) release in a murine macrophage/monocyte cell line. Pretreatment of cells with dexamethasone, a phospholipase A2 (PLA2) inhibitor, did not affect CT-induced 3H-AA release. In contrast, aspirin, which is an inhibitor of phospholipase C (PLC), blocked CT-induced 3H-AA release and subsequent prostaglandin (PC) synthesis. The inhibitory effect of aspirin was dose dependent, with 4 mM reducing the CT response by approximately 50%. Similarly, inhibition was time dependent, occurring when the drug was added to the culture medium as late as 30 min after CT. Brief exposure (30 min) of the cells to aspirin did not alter their subsequent response to CT, but 3H-AA release from cells exposed to aspirin for 2.5 h was irreversibly inhibited. The data suggested that CT stimulation of AA metabolism may involve increased PLC activity. 相似文献
8.
9.
R C Garcia C G Peterson A W Segal P Venge 《Biochemical and biophysical research communications》1985,132(3):1130-1136
Elastase in the human neutrophil is associated with various subpopulations of primary granules of different density. The proportion of this enzyme that is extracted with acetate pH 4.2 and cetyltrimethylammonium bromide varies in the different subpopulations. Nevertheless, the electrophoretic mobility and relative proportions of elastase isoenzymes is the same in both extracts from the different subpopulations. On stimulation of neutrophils with N-formylmethionylleucylphenylalanine, elastase is not released from the least dense subpopulation, whereas other two subpopulations do undergo degranulation to approximately the same extent. However, the release of elastase from these two denser granules differs after they are isolated and treated with calcium. 相似文献
10.