全文获取类型
收费全文 | 70355篇 |
免费 | 5991篇 |
国内免费 | 1355篇 |
出版年
2023年 | 363篇 |
2022年 | 352篇 |
2021年 | 1721篇 |
2020年 | 1170篇 |
2019年 | 1412篇 |
2018年 | 1812篇 |
2017年 | 1374篇 |
2016年 | 2207篇 |
2015年 | 3532篇 |
2014年 | 4034篇 |
2013年 | 4543篇 |
2012年 | 5698篇 |
2011年 | 5385篇 |
2010年 | 3455篇 |
2009年 | 2993篇 |
2008年 | 4067篇 |
2007年 | 3739篇 |
2006年 | 3472篇 |
2005年 | 3091篇 |
2004年 | 2963篇 |
2003年 | 2703篇 |
2002年 | 2264篇 |
2001年 | 1893篇 |
2000年 | 1742篇 |
1999年 | 1425篇 |
1998年 | 667篇 |
1997年 | 585篇 |
1996年 | 524篇 |
1995年 | 504篇 |
1994年 | 409篇 |
1993年 | 356篇 |
1992年 | 719篇 |
1991年 | 580篇 |
1990年 | 536篇 |
1989年 | 525篇 |
1988年 | 433篇 |
1987年 | 415篇 |
1986年 | 353篇 |
1985年 | 354篇 |
1984年 | 283篇 |
1983年 | 232篇 |
1982年 | 197篇 |
1981年 | 167篇 |
1980年 | 164篇 |
1979年 | 224篇 |
1978年 | 199篇 |
1977年 | 183篇 |
1976年 | 175篇 |
1974年 | 196篇 |
1972年 | 156篇 |
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
81.
82.
83.
84.
As a key factor for cell pluripotent and self-renewing phenotypes, SOX2 has attracted scientists’ attention gradually in recent years. However, its exact effects in dental pulp stem cells (DPSCs) are still unclear. In this study, we mainly investigated whether SOX2 could affect some biological functions of DPSCs. DPSCs were isolated from the dental pulp of human impacted third molar. SOX2 overexpressing DPSCs (DPSCs-SOX2) were established through retroviral infection. The effect of SOX2 on cell proliferation, migration and adhesion ability was evaluated with CCK-8, trans-well system and fibronectin-induced cell attachment experiment respectively. Whole genome expression of DPSCs-SOX2 was analyzed with RNA microarray. Furthermore, a rescue experiment was performed with SOX2-siRNA in DPSC-SOX2 to confirm the effect of SOX2 overexpression in DPSCs. We found that SOX2 overexpression could result in the enhancement of cell proliferation, migration, and adhesion in DPSCs obviously. RNA microarray analysis indicated that some key genes in the signal pathways associated with cell cycle, migration and adhesion were upregulated in different degree, and the results were further confirmed with qPCR and western-blot. Finally, DPSC-SOX2 transfected with SOX2-siRNA showed a decrease of cell proliferation, migration and adhesion ability, which further confirmed the biological effect of SOX2 in human DPSCs. This study indicated that SOX2 could improve the cell proliferation, migration and adhesion ability of DPSCs through regulating gene expression about cell cycle, migration and adhesion, and provided a novel strategy to develop seed cells with strong proliferation, migration and adhesion ability for tissue engineering. 相似文献
85.
86.
88 rice and 75 soybean samples were collected from 8 provinces of Korea from March through September in 1988. The Fusarium mycotoxins, zearalenone was analyzed by direct competitive enzyme linked immunosorbent assay. 10.2% of rice and 9.3 % of soybean samples contained detectable zearalenone. The average levels of zearalenone of rice and soybean samples were 11.78μg/kg and 7.70μ/kg, respectively. 相似文献
87.
Bruce Y. Lee Sarah M. Bartsch Marie C. Ferguson Patrick T. Wedlock Kelly J. OShea Sheryl S. Siegmund Sarah N. Cox James A. McKinnell 《PLoS computational biology》2021,17(1)
Finding medications or vaccines that may decrease the infectious period of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) could potentially reduce transmission in the broader population. We developed a computational model of the U.S. simulating the spread of SARS-CoV-2 and the potential clinical and economic impact of reducing the infectious period duration. Simulation experiments found that reducing the average infectious period duration could avert a median of 442,852 [treating 25% of symptomatic cases, reducing by 0.5 days, reproductive number (R0) 3.5, and starting treatment when 15% of the population has been exposed] to 44.4 million SARS-CoV-2 cases (treating 75% of all infected cases, reducing by 3.5 days, R0 2.0). With R0 2.5, reducing the average infectious period duration by 0.5 days for 25% of symptomatic cases averted 1.4 million cases and 99,398 hospitalizations; increasing to 75% of symptomatic cases averted 2.8 million cases. At $500/person, treating 25% of symptomatic cases saved $209.5 billion (societal perspective). Further reducing the average infectious period duration by 3.5 days averted 7.4 million cases (treating 25% of symptomatic cases). Expanding treatment to 75% of all infected cases, including asymptomatic infections (R0 2.5), averted 35.9 million cases and 4 million hospitalizations, saving $48.8 billion (societal perspective and starting treatment after 5% of the population has been exposed). Our study quantifies the potential effects of reducing the SARS-CoV-2 infectious period duration. 相似文献
88.
Xian-Hui Dong Dong-Xue Ma Tian-Ci Zhang Xiao-Ping He Li-Jun Xu Ya-Lei Liu Hao Li Wei-Juan Gao 《Neurochemical research》2021,46(5):1068-1080
Neurochemical Research - Alzheimer’s disease (AD) process is characterized classically by two hallmark pathologies: β-amyloid (Aβ) plaque deposition and neurofibrillary tangles of... 相似文献
89.
90.