全文获取类型
收费全文 | 418篇 |
免费 | 44篇 |
出版年
2021年 | 7篇 |
2019年 | 5篇 |
2018年 | 3篇 |
2017年 | 10篇 |
2016年 | 10篇 |
2015年 | 5篇 |
2014年 | 15篇 |
2013年 | 21篇 |
2012年 | 35篇 |
2011年 | 22篇 |
2010年 | 20篇 |
2009年 | 16篇 |
2008年 | 24篇 |
2007年 | 12篇 |
2006年 | 16篇 |
2005年 | 19篇 |
2004年 | 12篇 |
2003年 | 14篇 |
2002年 | 12篇 |
2001年 | 7篇 |
2000年 | 7篇 |
1999年 | 10篇 |
1998年 | 9篇 |
1997年 | 3篇 |
1995年 | 4篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 13篇 |
1990年 | 9篇 |
1989年 | 3篇 |
1988年 | 5篇 |
1987年 | 11篇 |
1986年 | 5篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1978年 | 2篇 |
1977年 | 5篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1972年 | 3篇 |
1971年 | 6篇 |
1970年 | 5篇 |
1969年 | 3篇 |
1967年 | 2篇 |
1937年 | 2篇 |
1925年 | 4篇 |
排序方式: 共有462条查询结果,搜索用时 31 毫秒
61.
62.
The crowns of several teeth of a captive killer whale, particularly on the mandible, were worn to the level of the pulp cavities by biting a cement structure in the pool. Food plugging partially vacant pulp cavities created intense vascularization, inflammation, and eventually a systemic focus for infection. This trauma correlated with an elevated white blood cell count. Haematology was restored to normal following regular care for the worn teeth. Patent drainage of the pulp cavity was maintained through routine brushing with a large-scale toothbrush. Administration of antibiotics was not necessary in controlling the white blood cell count. 相似文献
63.
64.
65.
66.
67.
68.
Circadian Nature of a Rhythm Expressed by an Invertaseless Strain of Neurospora crassa 总被引:37,自引:13,他引:24
A new strain of Neurospora crassa which exhibits a rhythm of conidiation when growing along an agar surface in a growth tube is described. The rhythm has been shown to be circadian for it meets the following criteria: A) the period under constant environmental conditions in the dark is about 24 hours (22.7 hours at 25 degrees ); B) the period is relatively temperature-independent (Q(10) is between 0.95 and 1.21 for temperature range of 18 to 35 degrees ); C) the rhythm persists in continuous darkness at constant temperature for a minimum of 14 days without damping out; and D) the phase of the rhythm can be shifted by a single brief exposure to light. The sensitivity of this strain to light has been demonstrated further by the entrainment of the rhythm to a period of 24.0 hours using a suitable light-dark regime, and by the inhibition by light of the appearance of a rhythm; i.e., continuous conidiation occurs when the strain is subjected to continuous light. The new strain is compared to 2 other strains of Neurospora which also express a rhythm, patch and clock. 相似文献
69.
Virus-infected monocytes rarely are detected in the bloodstreams of animals or people infected with immunodeficiency-inducing lentiviruses, yet tissue macrophages are thought to be a major reservoir of virus-infected cells in vivo. We have identified feline immunodeficiency virus (FIV) clinical isolates that are pathogenic in cats and readily transmitted vertically. We report here that five of these FIV isolates are highly monocytotropic in vivo. However, while FIV-infected monocytes were numerous in the blood of experimentally infected cats, viral antigen was not detectable in freshly isolated cells. Only after a short-term (at least 12-h) in vitro monocyte culture were FIV antigens detectable (by immunocytochemical analysis or enzyme-linked immunosorbent assay). In vitro experiments suggested that monocyte adherence provided an important trigger for virus antigen expression. In the blood of cats infected with a prototype monocytotropic isolate (FIV subtype B strain 2542), infected monocytes appeared within 2 weeks, correlating with high blood mononuclear-cell-associated viral titers and CD4 cell depletion. By contrast, infected monocytes could not be detected in the blood of cats infected with a less pathogenic FIV strain (FIV subtype A strain Petaluma). We concluded that some strains of FIV are monocytotropic in vivo. Moreover, this property may relate to virus virulence, vertical transmission, and infection of tissue macrophages. 相似文献
70.
Manahil M. Abdalhameed Pingwei Zhao Dow P. Hurst Patricia H. Reggio Mary E. Abood Mitchell P. Croatt 《Bioorganic & medicinal chemistry letters》2017,27(3):612-615
The first structure-activity relationships for a benzothiazole scaffold acting as an antagonist at GPR35 is presented. Analogues were designed based on a lead compound that was previously determined to have selective activity as a GPR35 antagonist. The synthetic route was modular in nature to independently explore the role of the middle and both ends of the scaffold. The activities of the analogues illustrate the importance of all three segments of the compound. 相似文献