全文获取类型
收费全文 | 8000篇 |
免费 | 711篇 |
国内免费 | 571篇 |
专业分类
9282篇 |
出版年
2024年 | 20篇 |
2023年 | 114篇 |
2022年 | 278篇 |
2021年 | 448篇 |
2020年 | 299篇 |
2019年 | 349篇 |
2018年 | 325篇 |
2017年 | 236篇 |
2016年 | 386篇 |
2015年 | 512篇 |
2014年 | 660篇 |
2013年 | 596篇 |
2012年 | 715篇 |
2011年 | 609篇 |
2010年 | 430篇 |
2009年 | 340篇 |
2008年 | 417篇 |
2007年 | 399篇 |
2006年 | 293篇 |
2005年 | 253篇 |
2004年 | 201篇 |
2003年 | 189篇 |
2002年 | 136篇 |
2001年 | 141篇 |
2000年 | 133篇 |
1999年 | 149篇 |
1998年 | 94篇 |
1997年 | 81篇 |
1996年 | 68篇 |
1995年 | 48篇 |
1994年 | 59篇 |
1993年 | 32篇 |
1992年 | 49篇 |
1991年 | 39篇 |
1990年 | 23篇 |
1989年 | 31篇 |
1988年 | 22篇 |
1987年 | 30篇 |
1986年 | 13篇 |
1985年 | 20篇 |
1984年 | 12篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1948年 | 1篇 |
1947年 | 1篇 |
排序方式: 共有9282条查询结果,搜索用时 15 毫秒
81.
82.
Zhang Keji Gao Yuan Deng Yuxiao Zhou Xiao Zhu Changqing He Zhengyu Lv Dan 《Molecular and cellular biochemistry》2021,476(1):93-107
Molecular and Cellular Biochemistry - Mesenchymal stem cells (MSCs) can alleviate acute respiratory distress syndrome (ARDS), but the mechanisms involved are unclear, especially about their... 相似文献
83.
Shao Xiao Liu Zhaozheng Liu Shanshan Lin Na Deng Yue 《Molecular and cellular biochemistry》2021,476(4):1783-1795
Molecular and Cellular Biochemistry - Non-coding RNAs (ncRNAs) have shown to act as crucial mediators in atherosclerosis (AS) development. The purpose of our study was to explore the role of... 相似文献
84.
Wei Tong Ruopei Li Jin Huang Huijuan Zhao Ruoheng Ge Qiong Wu Ali I. Mallano Yanli Wang Fangdong Li Weiwei Deng Yeyun Li Enhua Xia 《The Plant journal : for cell and molecular biology》2021,106(5):1312-1327
The tea plant (Camellia sinensis) is a thermophilic cash crop and contains a highly duplicated and repeat-rich genome. It is still unclear how DNA methylation regulates the evolution of duplicated genes and chilling stress in tea plants. We therefore generated a single-base-resolution DNA methylation map of tea plants under chilling stress. We found that, compared with other plants, the tea plant genome is highly methylated in all three sequence contexts, including CG, CHG and CHH (where H = A, T, or C), which is further proven to be correlated with its repeat content and genome size. We show that DNA methylation in the gene body negatively regulates the gene expression of tea plants, whereas non-CG methylation in the flanking region enables a positive regulation of gene expression. We demonstrate that transposable element-mediated methylation dynamics significantly drives the expression divergence of duplicated genes in tea plants. The DNA methylation and expression divergence of duplicated genes in the tea plant increases with evolutionary age and selective pressure. Moreover, we detect thousands of differentially methylated genes, some of which are functionally associated with chilling stress. We also experimentally reveal that DNA methyltransferase genes of tea plants are significantly downregulated, whereas demethylase genes are upregulated at the initial stage of chilling stress, which is in line with the significant loss of DNA methylation of three well-known cold-responsive genes at their promoter and gene body regions. Overall, our findings underscore the importance of DNA methylation regulation and offer new insights into duplicated gene evolution and chilling tolerance in tea plants. 相似文献
85.
Tao Zhang Shuai Guo Han Zhou Zhimin Wu Junfeng Liu Changwei Qiu Ganzhen Deng 《Cell proliferation》2021,54(2)
BackgroundIn mammals, early pregnancy is a critical vulnerable period during which complications may arise, including pregnancy failure. Establishment of a maternal endometrial acceptance phenotype is a prerequisite for semiheterogeneous embryo implantation, comprising the rate‐limiting step of early pregnancy.MethodsConfocal fluorescence, immunohistochemistry and western blot for nuclear and cytoplasmic protein were used to examine the activation of yes‐associated protein (YAP) in uterine tissue and primary endometrial cells. The target binding between miR16a and YAP was verified by dual‐luciferase reporter gene assay. The mouse pregnancy model and pseudopregnancy model were used to investigate the role of YAP in the maternal uterus during early pregnancy in vivo.ResultsWe showed that YAP translocates into the nucleus in the endometrium of cattle and mice during early pregnancy. Mechanistically, YAP acts as a mediator of ECM rigidity and cell density, which requires the actomyosin cytoskeleton and is partially dependent on the Hippo pathway. Furthermore, we found that the soluble factor IFNτ, which is a ruminant pregnancy recognition factor, also induced activation of YAP by reducing the expression of miR‐16a.ConclusionsThis study revealed that activation of YAP is necessary for early pregnancy in bovines because it induced cell proliferation and established an immunosuppressive local environment that allowed conceptus implantation into the uterine epithelium. 相似文献
86.
87.
88.
89.
90.
Duan Yali Li Changchong Deng Li An Shuhua Zhu Yun Wang Wei Zhang Meng Xu Lili Xu Baoping Chen Xiangpeng Xie Zhengde 《中国病毒学》2021,36(3):382-392
To investigate the molecular epidemiology and genetic variation of human adenovirus type 7(HAdV-7) in children with acute respiratory infections(ARI) in China. HAdV-7-positive respiratory samples collected from children with ARI in Beijing, Shijiazhuang, Wenzhou and Guangzhou from 2014–2018 were selected for gene amplification and sequence analysis. Fifty-seven HAdV-7 clinical strains with hexon, penton base and fiber gene sequences were obtained. Meanwhile17 strains were selected randomly from different cities for whole genome sequencing. Phylogenetic and variation analyses were performed based on the obtained sequences, HAdV-7 prototype strain Gomen(AY594255), vaccine strains(AY495969 and AY594256) and representative sequences of strains. The phylogenetic trees constructed based on whole genome sequences, major capsid protein genes(hexon, penton base and fiber) and the early genes(E1, E2, E3 and E4) were not completely consistent. The HAdV-7 strains obtained in this study always clustered with most of the circulating strains worldwide from the 1980 s to the present. Compared with the HAdV-7 prototype strain Gomen(AY594255), some amino acid mutations in loop1 and loop2 of hexon and the RGD loop region of the penton base gene were observed. Recombination analysis showed that partial regions of 55 k Da protein and 100 kDa hexon-assembly associated protein genes among all HAdV-7 strains in this study were from HAdV-16 and HAdV-3, respectively. Our study demonstrated the molecular evolution characteristics of HAdV-7 strains circulating in China and provided basic reference data for the prevention, control and vaccine development of HAdV-7. 相似文献