全文获取类型
收费全文 | 43162篇 |
免费 | 3964篇 |
国内免费 | 19篇 |
出版年
2023年 | 232篇 |
2022年 | 279篇 |
2021年 | 1189篇 |
2020年 | 677篇 |
2019年 | 857篇 |
2018年 | 1034篇 |
2017年 | 877篇 |
2016年 | 1340篇 |
2015年 | 2195篇 |
2014年 | 2445篇 |
2013年 | 2611篇 |
2012年 | 3643篇 |
2011年 | 3299篇 |
2010年 | 2137篇 |
2009年 | 1825篇 |
2008年 | 2625篇 |
2007年 | 2562篇 |
2006年 | 2310篇 |
2005年 | 2173篇 |
2004年 | 2001篇 |
2003年 | 1901篇 |
2002年 | 1720篇 |
2001年 | 466篇 |
2000年 | 348篇 |
1999年 | 425篇 |
1998年 | 463篇 |
1997年 | 318篇 |
1996年 | 289篇 |
1995年 | 251篇 |
1994年 | 261篇 |
1993年 | 260篇 |
1992年 | 287篇 |
1991年 | 267篇 |
1990年 | 274篇 |
1989年 | 238篇 |
1988年 | 249篇 |
1987年 | 224篇 |
1986年 | 192篇 |
1985年 | 183篇 |
1984年 | 199篇 |
1983年 | 159篇 |
1982年 | 180篇 |
1981年 | 166篇 |
1980年 | 154篇 |
1979年 | 126篇 |
1978年 | 128篇 |
1977年 | 121篇 |
1976年 | 104篇 |
1974年 | 89篇 |
1973年 | 99篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
Dual roles of plcA in Listeria monocytogenes pathogenesis 总被引:26,自引:5,他引:21
75.
Daniel A. Bradburd 《Human ecology: an interdisciplinary journal》1996,24(1):1-38
It has become a theoretical commonplace among students of southwest Asian pastoralism that the balance of exchange between pastoralists and their settled neighbors has had a profound effect on pastoralists, strongly influencing household viability and, indeed, the viability of pastoralism as an adaptation. However, little attempt has been made to examine historical variation in the balance of exchange. Attempts to use transformations in the balance of exchange as a means of accounting for change among pastoralists thus remain largely impressionistic and underspecified. This paper examines variations in the balance of exchange between Iranian pastoralists and non-pastoralists from 1815 to 1977. It demonstrates that to the degree that there were long term shifts in the balance of exchange, they favored pastoralists, and it argues that this trend became stronger, rather than weaker in the 20th century. This suggests that pressures on pastoralists over this period were not directly economic and that variation in the balance of exchange itself cannot account for outcomes such as the increased settlement of Iranian pastoralists. 相似文献
76.
Xu Zhang Wei Zhang Santosh L. Saraf Mehdi Nouraie Jin Han Michel Gowhari Johara Hassan Galina Miasnikova Adelina Sergueeva Sergei Nekhai Rick Kittles Roberto F. Machado Joe G. N. Garcia Mark T. Gladwin Martin H. Steinberg Paola Sebastiani Donald A. McClain Victor R. Gordeuk 《Human genetics》2015,134(8):895-904
77.
78.
Cynthia Nafula Wakhungu Isaiah Masinde Tabu O. Daniel Otaye Wafula Victor Wasike 《Archives Of Phytopathology And Plant Protection》2017,50(7-8):398-414
A study was carried out to determine Fusarium wilt distribution in Bambara nut farmers’ fields and its management using farm yard manure (FYM). Four villages in Busia County were purposively sampled for the study. The data generated were subjected to analysis of variance and treatment means separated by least significant difference test. Fusarium wilt incidence in the fields ranged from 14.63 to 43.56%. In the greenhouse, FYM reduced the disease incidence by 10.2% and severity by 9.5% on the black landrace and 1.9 and 12.8%, respectively, on the red landrace. In the field, FYM reduced disease incidence by 9.1% and severity by 6.9% on the black landrace and 10.4 and 10.4%, respectively, on the red landrace. Farm yard manure had the lowest area under disease progress curve irrespective of the landrace. The study confirmed the presence of the pathogen in the fields and the ability to manage the disease using FYM. 相似文献
79.
Mathieu Lefèvre Daniel J. Felmlee Marie Parnot Thomas F. Baumert Catherine Schuster 《PloS one》2014,9(4)
Hepatitis C virus (HCV) is a major cause of liver disease worldwide and HCV infection represents a major health problem. HCV associates with host lipoproteins forming host/viral hybrid complexes termed lipoviral particles. Apolipoprotein E (apoE) is a lipoprotein component that interacts with heparan sulfate proteoglycans (HSPG) to mediate hepatic lipoprotein uptake, and may likewise mediate HCV entry. We sought to define the functional regions of apoE with an aim to identify critical apoE binding partners involved in HCV infection. Using adenoviral vectors and siRNA to modulate apoE expression we show a direct correlation of apoE expression and HCV infectivity, whereas no correlation exists with viral protein expression. Mutating the HSPG binding domain (HSPG-BD) of apoE revealed key residues that are critical for mediating HCV infection. Furthermore, a novel synthetic peptide that mimics apoE’s HSPG-BD directly and competitively inhibits HCV infection. Genetic knockdown of the HSPG proteins syndecan (SDC) 1 and 4 revealed that SDC4 principally mediates HCV entry. Our data demonstrate that HCV uses apoE-SDC4 interactions to enter hepatoma cells and establish infection. Targeting apoE-SDC interactions could be an alternative strategy for blocking HCV entry, a critical step in maintaining chronic HCV infection. 相似文献
80.