全文获取类型
收费全文 | 255篇 |
免费 | 51篇 |
专业分类
306篇 |
出版年
2022年 | 3篇 |
2016年 | 2篇 |
2015年 | 11篇 |
2014年 | 6篇 |
2013年 | 8篇 |
2012年 | 15篇 |
2011年 | 13篇 |
2010年 | 6篇 |
2009年 | 4篇 |
2008年 | 9篇 |
2007年 | 11篇 |
2006年 | 11篇 |
2005年 | 9篇 |
2004年 | 7篇 |
2003年 | 7篇 |
2002年 | 8篇 |
2001年 | 5篇 |
2000年 | 2篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1990年 | 6篇 |
1988年 | 4篇 |
1987年 | 11篇 |
1986年 | 7篇 |
1985年 | 4篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 6篇 |
1974年 | 4篇 |
1973年 | 3篇 |
1972年 | 6篇 |
1971年 | 7篇 |
1970年 | 5篇 |
1969年 | 6篇 |
1968年 | 6篇 |
1967年 | 6篇 |
1964年 | 2篇 |
1940年 | 2篇 |
排序方式: 共有306条查询结果,搜索用时 15 毫秒
21.
22.
Dodd KA Bird BH Khristova ML Albariño CG Carroll SA Comer JA Erickson BR Rollin PE Nichol ST 《PLoS neglected tropical diseases》2011,5(10):e1352
Background
Alkhurma hemorrhagic fever virus (AHFV) and Kyasanur forest disease virus (KFDV) cause significant human disease and mortality in Saudi Arabia and India, respectively. Despite their distinct geographic ranges, AHFV and KFDV share a remarkably high sequence identity. Given its emergence decades after KFDV, AHFV has since been considered a variant of KFDV and thought to have arisen from an introduction of KFDV to Saudi Arabia from India. To gain a better understanding of the evolutionary history of AHFV and KFDV, we analyzed the full length genomes of 16 AHFV and 3 KFDV isolates.Methodology/Principal Findings
Viral genomes were sequenced and compared to two AHFV sequences available in GenBank. Sequence analyses revealed higher genetic diversity within AHFVs isolated from ticks than human AHFV isolates. A Bayesian coalescent phylogenetic analysis demonstrated an ancient divergence of AHFV and KFDV of approximately 700 years ago.Conclusions/Significance
The high sequence diversity within tick populations and the presence of competent tick vectors in the surrounding regions, coupled with the recent identification of AHFV in Egypt, indicate possible viral range expansion or a larger geographic range than previously thought. The divergence of AHFV from KFDV nearly 700 years ago suggests other AHFV/KFDV-like viruses might exist in the regions between Saudi Arabia and India. Given the human morbidity and mortality associated with these viruses, these results emphasize the importance of more focused study of these significant public health threats. 相似文献23.
24.
25.
26.
27.
28.
29.
CD21/CD19 coreceptor signaling promotes B cell survival during primary immune responses 总被引:2,自引:0,他引:2
Barrington RA Zhang M Zhong X Jonsson H Holodick N Cherukuri A Pierce SK Rothstein TL Carroll MC 《Journal of immunology (Baltimore, Md. : 1950)》2005,175(5):2859-2867
The adaptive immune response is tightly regulated to limit responding cells in an Ag-specific manner. On B cells, coreceptors CD21/CD19 modulate the strength of BCR signals, potentially influencing cell fate. The importance of the CD95 pathway was examined in response of B cells to moderate affinity Ag using an adoptive transfer model of lysozyme-specific Ig transgenic (HEL immunoglobulin transgene (MD4) strain) B cells. Although adoptively transferred Cr2+/+ MD4 B cells are activated and persist within splenic follicles of duck egg lysozyme-immunized mice, Cr2-/- MD4 B cells do not. In contrast, Cr2-/- MD4 lpr B cells persist after transfer, suggesting that lack of CD21/CD35 signaling results in CD95-mediated elimination. Cr2 deficiency did not affect CD95 levels, but cellular FLIP (c-FLIP) protein and mRNA levels were reduced 2-fold compared with levels in Cr2+/+ MD4 B cells. In vitro culture with Cr2+/+ MD4 B cells demonstrated that equimolar amounts of rHEL-C3d3 were more effective than hen egg lysozyme alone in up-regulating c-FLIP levels and for protection against CD95-mediated apoptosis. Collectively, this study implies a mechanism for regulating B cell survival in vivo whereby the strength of BCR signaling (including coreceptor) determines c-FLIP levels and protection from CD95-induced death. 相似文献
30.
Brian R. Amman Serena A. Carroll Zachary D. Reed Tara K. Sealy Stephen Balinandi Robert Swanepoel Alan Kemp Bobbie Rae Erickson James A. Comer Shelley Campbell Deborah L. Cannon Marina L. Khristova Patrick Atimnedi Christopher D. Paddock Rebekah J. Kent Crockett Timothy D. Flietstra Kelly L. Warfield Robert Unfer Edward Katongole-Mbidde Robert Downing Jordan W. Tappero Sherif R. Zaki Pierre E. Rollin Thomas G. Ksiazek Stuart T. Nichol Jonathan S. Towner 《PLoS pathogens》2012,8(10)
Marburg virus (family Filoviridae) causes sporadic outbreaks of severe hemorrhagic disease in sub-Saharan Africa. Bats have been implicated as likely natural reservoir hosts based most recently on an investigation of cases among miners infected in 2007 at the Kitaka mine, Uganda, which contained a large population of Marburg virus-infected Rousettus aegyptiacus fruit bats. Described here is an ecologic investigation of Python Cave, Uganda, where an American and a Dutch tourist acquired Marburg virus infection in December 2007 and July 2008. More than 40,000 R. aegyptiacus were found in the cave and were the sole bat species present. Between August 2008 and November 2009, 1,622 bats were captured and tested for Marburg virus. Q-RT-PCR analysis of bat liver/spleen tissues indicated ∼2.5% of the bats were actively infected, seven of which yielded Marburg virus isolates. Moreover, Q-RT-PCR-positive lung, kidney, colon and reproductive tissues were found, consistent with potential for oral, urine, fecal or sexual transmission. The combined data for R. aegyptiacus tested from Python Cave and Kitaka mine indicate low level horizontal transmission throughout the year. However, Q-RT-PCR data show distinct pulses of virus infection in older juvenile bats (∼six months of age) that temporarily coincide with the peak twice-yearly birthing seasons. Retrospective analysis of historical human infections suspected to have been the result of discrete spillover events directly from nature found 83% (54/65) events occurred during these seasonal pulses in virus circulation, perhaps demonstrating periods of increased risk of human infection. The discovery of two tags at Python Cave from bats marked at Kitaka mine, together with the close genetic linkages evident between viruses detected in geographically distant locations, are consistent with R. aegyptiacus bats existing as a large meta-population with associated virus circulation over broad geographic ranges. These findings provide a basis for developing Marburg hemorrhagic fever risk reduction strategies. 相似文献