全文获取类型
收费全文 | 20750篇 |
免费 | 1956篇 |
国内免费 | 1222篇 |
出版年
2023年 | 229篇 |
2022年 | 291篇 |
2021年 | 918篇 |
2020年 | 657篇 |
2019年 | 888篇 |
2018年 | 814篇 |
2017年 | 632篇 |
2016年 | 823篇 |
2015年 | 1200篇 |
2014年 | 1372篇 |
2013年 | 1555篇 |
2012年 | 1832篇 |
2011年 | 1686篇 |
2010年 | 1041篇 |
2009年 | 904篇 |
2008年 | 1054篇 |
2007年 | 953篇 |
2006年 | 845篇 |
2005年 | 721篇 |
2004年 | 628篇 |
2003年 | 546篇 |
2002年 | 476篇 |
2001年 | 432篇 |
2000年 | 381篇 |
1999年 | 335篇 |
1998年 | 206篇 |
1997年 | 180篇 |
1996年 | 190篇 |
1995年 | 149篇 |
1994年 | 153篇 |
1993年 | 111篇 |
1992年 | 177篇 |
1991年 | 159篇 |
1990年 | 119篇 |
1989年 | 124篇 |
1988年 | 93篇 |
1987年 | 107篇 |
1986年 | 98篇 |
1985年 | 83篇 |
1984年 | 88篇 |
1983年 | 78篇 |
1982年 | 49篇 |
1980年 | 31篇 |
1979年 | 45篇 |
1977年 | 32篇 |
1976年 | 34篇 |
1975年 | 28篇 |
1974年 | 33篇 |
1973年 | 39篇 |
1972年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
1.
Single Cell Transcriptome Amplification with MALBAC 总被引:1,自引:0,他引:1
2.
ObjectiveWe investigated whether glutamate, NMDA receptors, and eukaryote elongation factor-2 kinase (eEF-2K)/eEF-2 regulate P-glycoprotein expression, and the effects of the eEF-2K inhibitor NH125 on the expression of P-glycoprotein in rat brain microvessel endothelial cells (RBMECs).MethodsCortex was obtained from newborn Wistar rat brains. After surface vessels and meninges were removed, the pellet containing microvessels was resuspended and incubated at 37°C in culture medium. Cell viability was assessed by the MTT assay. RBMECs were identified by immunohistochemistry with anti-vWF. P-glycoprotein, phospho-eEF-2, and eEF-2 expression were determined by western blot analysis. Mdr1a gene expression was analyzed by RT-PCR.ResultsMdr1a mRNA, P-glycoprotein and phospho-eEF-2 expression increased in L-glutamate stimulated RBMECs. P-glycoprotein and phospho-eEF-2 expression were down-regulated after NH125 treatment in L-glutamate stimulated RBMECs.ConclusionseEF-2K/eEF-2 should have played an important role in the regulation of P-glycoprotein expression in RBMECs. eEF-2K inhibitor NH125 could serve as an efficacious anti-multidrug resistant agent. 相似文献
3.
4.
Identification of a hypervariable region in the long terminal repeat of equine infectious anemia virus. 总被引:13,自引:10,他引:3 下载免费PDF全文
An avirulent, field-derived isolate of equine infectious anemia virus (EIAV), designated MA-1, was molecularly cloned, and the complete nucleotide sequence was determined for the 3' half of the viral genome. Comparisons between MA-1 and the prototype Wyoming strain of EIAV identified a 66-nucleotide stretch between CAAT (-91) and TATAA (-25) in the U3 region of the long terminal repeat, where sequence divergence was as high as 39.3%. The polymerase chain reaction was used to amplify and clone long terminal repeat sequences from Th-1, the in vivo parental stock of MA-1. Results indicated that the nucleotide sequences of MA-1 and Th-1 clones were less variable than was observed between MA-1 and Wyoming. However, MA-1 and Th-1 markedly differed in the types of enhancer sequences located in the hypervariable region. These results suggest that variation in lentivirus regulatory sequences may be important in EIAV host cell tropism and pathogenesis. 相似文献
5.
Duoru Lin Jingjing Chen Zhuoling Lin Xiaoyan Li Xiaohang Wu Erping Long Lixia Luo Bo Zhang Hui Chen Wan Chen Li Zhang Haotian Lin Weirong Chen Yizhi Liu 《PloS one》2015,10(11)
A review of 6 years of hospitalization charts from Zhongshan Ophthalmic Center (ZOC) revealed that congenital cataracts (CC) accounted for 2.39% of all cataract in-patient cases and that the age at surgery was decreasing before the establishment of the Childhood Cataract Program of the Chinese Ministry of Health (CCPMOH) in December 2010. We aimed to investigate data from the 4 years (January 2011 to December 2014) following the establishment of the CCPMOH, compared, and combined with data from the previous study period (January 2005 to December 2010) to generate a 10-year overview of the hospital-based prevalence and treatment of CC. In the 4-year period after CCPMOH establishment, the prevalence of CC was 2.01% in all hospitalizations, and was 2.78% in all cataract in-patients. Most of the eligible CC in-patients (71%) lived in south China. The ratio of boys to girls was 1.42:1. Nearly 2/3 of the patients underwent cataract extraction with primary intraocular lens (IOL) implantation at a mean age of 78.40±51.45 months, and cataract extraction surgeries without IOL implantation were performed in the remaining 1/3 of patients at a mean age of 10.03±15.92 months. After CCPMOH establishment, an increased incidence of CC was revealed, and the CC in-patients were younger than the patients in the previous period. The 10-year overview (2421 CC in-patients from 206630 hospitalizations) revealed upward trends in both the number and the prevalence of CC and a further reduction in age at surgery. In conclusion, the data from 4-year period after CCPMOH establishment and the 10-year overview showed upward trends in the hospital-based prevalence of CC cases and a further reduction in age at surgery, likely reflecting the effects of the CCPMOH establishment and providing useful information for further CC studies and a valuable foundation for the prevention and treatment of this cause of childhood blindness. 相似文献
6.
Yan Xue Liu Jia Wu Ke-Xin Yang Nan Pan Li-Ben Song Ying Liu Yang Tang Zhong-Hua 《Journal of Plant Growth Regulation》2022,41(6):2421-2434
Journal of Plant Growth Regulation - Early-spring plants are a special type of plant that complete their life cycle promptly in cold, early spring. Very little effort has been made into researching... 相似文献
7.
8.
9.
10.
Glycoprotein O (gO) is conserved among betaherpesviruses, but little is known about the maturation process of gO in human herpesvirus 6 (HHV-6). We found that HHV-6 gO maturation was accompanied by cleavage of its carboxyl terminus and required coexpression of gH and gL, which promoted the export of gO out of the endoplasmic reticulum (ER). Finally, we also found that gO was not required for HHV-6A growth in T cells. 相似文献