全文获取类型
收费全文 | 8878篇 |
免费 | 697篇 |
国内免费 | 827篇 |
出版年
2024年 | 30篇 |
2023年 | 152篇 |
2022年 | 337篇 |
2021年 | 596篇 |
2020年 | 390篇 |
2019年 | 433篇 |
2018年 | 444篇 |
2017年 | 331篇 |
2016年 | 411篇 |
2015年 | 588篇 |
2014年 | 666篇 |
2013年 | 695篇 |
2012年 | 852篇 |
2011年 | 742篇 |
2010年 | 460篇 |
2009年 | 390篇 |
2008年 | 430篇 |
2007年 | 379篇 |
2006年 | 318篇 |
2005年 | 268篇 |
2004年 | 216篇 |
2003年 | 185篇 |
2002年 | 150篇 |
2001年 | 106篇 |
2000年 | 113篇 |
1999年 | 107篇 |
1998年 | 84篇 |
1997年 | 85篇 |
1996年 | 55篇 |
1995年 | 57篇 |
1994年 | 72篇 |
1993年 | 35篇 |
1992年 | 40篇 |
1991年 | 33篇 |
1990年 | 26篇 |
1989年 | 31篇 |
1988年 | 16篇 |
1987年 | 15篇 |
1986年 | 10篇 |
1985年 | 20篇 |
1984年 | 6篇 |
1983年 | 8篇 |
1982年 | 7篇 |
1981年 | 1篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1975年 | 1篇 |
1950年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
211.
Gap junctions formed by two hemichannels from two neighboring cells are cell-to-cell communication channels; hemichannels are communication channels between intracellular and extracellular environments. Hemichannels are hexameric proteins formed by connexins, pannexins, innexins and vinnexins. Innexin-hemichannels (innexons) exist in the lepidopteran cell surface, but their component innexins and functions have not been reported. Recent studies by others have demonstrated that hemichannels, connexons and pannexons from vertebrates serve as regulators of apoptosis via inactivating the PI3K/Akt signaling pathway. Here, the apoptogenic properties of innexons are demonstrated using two innexin cDNAs, Spli-inx2 and Spli-inx3, which were isolated from hemocytes of lepidopteran Spodoptera litura. Alignment analysis revealed that these two genes belong to a conserved innexin family, as they contain the insect signature YYQWV motif at the beginning of the second transmembrane domain. Immunofluorescence showed that two fusion proteins, Inx2-V5 and Inx3-V5, were localized predominantly in the cell membrane, cytoplasm and also nuclei. Ectopic expression in Sf9 cells and over-expression of Inx2 and Inx3 in Spli221 cells promoted apoptosis. In the Spli221 cells, apoptotic cells presented remarkable membrane blebbing. This study also showed that Sf9 and Spli221 cells undergo low level apoptosis under normal culture conditions, but not Hi5 cells. In Hi5 stable cell lines, biotinylation was used to isolate surface proteins and confirm Inx2 and Inx3 localization in the cell membrane and also further data showed that Hi5 cells may activate the PI3K signaling pathway via phosphorylating molecular Akt downstream. This result suggests that innexon-promoted apoptosis may be involving the PI3K/Akt signaling pathway. These findings will facilitate further examinations of the apoptotic regulation by the PI3K/Akt signaling pathway and comparative studies of innexons, connexons, pannexons, and vinnexons. 相似文献
212.
Vesicular trafficking plays a crucial role in protein localization and movement, signal transduction, and multiple developmental processes in eukaryotic cells. Vesicle fusion is the final and key step in vesicle-mediated trafficking and mainly relies on SNAREs (soluble N-ethylmaleimide-sensitive factor attachment protein receptors), the regulators including SM (Sec1/Munc18) family proteins, Rab GTPases and exocyst subunits. Verticillium dahliae is a widespread soil fungus that causes disruptive vascular diseases on a wide range of plants. To date, no genes involved in vesicular fusion process have been identified and characterized in V. dahliae. The recent publication of the draft genome sequence of V. dahliae allowed us to conduct a genome-wide identification, phylogeny and expression profile of genes encoding vesicular fusion components. Using compared genomics and phylogenetic methods, we identified 44 genes encoding vesicle fusion components in the V. dahliae genome. According to the structural features of their encoded proteins, the 44 V. dahliae genes were classified into 22 SNAREs (6 Qa-, 4 Qb-, 6 Qc-, 1 Qbc- and 5 R-types), 4 SM family proteins, 10 Rab GTPases and 8 exocyst proteins. Based on phylogeny and motif constitution analysis, orthologs of vesicle fusion component in filamentous fungi were generally clustered together into the same subclasses with well-supported bootstrap values. Analysis of the expression profiles of these genes indicated that many of them are significantly differentially expressed during vegetative growth and microsclerotia formation in V. dahliae. The analysis show that many components of vesicle fusion are well conserved in filamentous fungi and indicate that vesicle fusion plays a critical role in microsclerotia formation of smoke tree wilt fungus V. dahliae. The genome-wide identification and expression analysis of components involved in vesicle fusion should facilitate research in this gene family and give new insights toward elucidating their functions in growth, development and pathogenesis of V. dahliae. 相似文献
213.
H. Irene Hall Jessica Halverson David P. Wilson Barbara Suligoi Mercedes Diez Stéphane Le Vu Tian Tang Ann McDonald Laura Camoni Caroline Semaille Chris Archibald 《PloS one》2013,8(11)
Background
Testing for HIV infection and entry to care are the first steps in the continuum of care that benefit individual health and may reduce onward transmission of HIV. We determined the percentage of people with HIV who were diagnosed late and the percentage linked into care overall and by demographic and risk characteristics by country.Methods
Data were analyzed from national HIV surveillance systems. Six countries, where available, provided data on two late diagnosis indicators (AIDS diagnosis within 3 months of HIV diagnosis, and AIDS diagnosis within 12 months before HIV diagnosis) and linkage to care (≥1 CD4 or viral load test result within 3 months of HIV diagnosis) for people diagnosed with HIV in 2009 or 2010 (most recent year data were available).Principal Findings
The percentage of people presenting with late stage disease at HIV diagnosis varied by country, overall with a range from 28.7% (United States) to 8.8% (Canada), and by transmission categories. The percentage of people diagnosed with AIDS who had their initial HIV diagnosis within 12 months before AIDS diagnosis varied little among countries, except the percentages were somewhat lower in Spain and the United States. Overall, the majority of people diagnosed with HIV were linked to HIV care within 3 months of diagnosis (more than 70%), but varied by age and transmission category.Conclusions
Differences in patterns of late presentation at HIV diagnosis among countries may reflect differences in screening practices by providers, public health agencies, and people with HIV. The percentage of people who received assessments of immune status and viral load within 3 months of diagnosis was generally high. 相似文献214.
215.
Plant and Soil - Global change is shown to significantly affect the C storage function of peatlands; however, a majority of previous research is focused on a single environmental stressor such as... 相似文献
216.
Wang Y. Tian T. Li X. Tang L. Li Y. Wang H. Zhang J. Zhang L. Zhang X. 《Microbiology》2020,89(1):122-128
Microbiology - An aerobic, gram-negative-staining, motile and rod-shaped bacterium, designated strain 3-BNT, was isolated from sewage sediment collected from Baiyangdian, located in Xiongan New... 相似文献
217.
Li Bingxin Li Wanyan Tian Yunbo Guo Sixuan Qian Long Xu Danning Cao Nan 《Biological trace element research》2020,193(2):508-516
Biological Trace Element Research - Selenium (Se) has been well recognized as an immune-enhancing agent with antioxidant and anti-tumor properties. The commonly used chemotherapy drug,... 相似文献
218.
219.
Rongkun Li Li Weng Bingyan Liu Lili Zhu Xiaoxin Zhang Guangang Tian Lipeng Hu Qing Li Shuheng Jiang Mingyi Shang 《Journal of cellular biochemistry》2020,121(2):1986-1997
Aberrant expression of the tripartite motif containing 59 (TRIM59) has been reported to participate in the development and progression of various human cancers. However, its expression pattern and cellular roles in pancreatic cancer (PC) remains unclear. In our study, we found that TRIM59 expression was significantly increased in PC tissues and was positively correlated with several malignant behaviors and poor overall survival of PC patients based on bioinformatics analysis and immunohistochemistry staining. Functionally, small interfering RNA–mediated TRIM59 depletion inhibited cell proliferation and migration in vitro, while TRIM59 overexpression promoted cell proliferation and migration in vitro and drove tumor growth and liver metastasis in vivo. Mechanically, TRIM59 was found to enhance glycolysis through activating the PI3K/AKT/mTOR pathway, ultimately contributing to PC progression. Taken together, our results demonstrate that TRIM59 may be a potential predictor for PC and promotes PC progression via the PI3K/AKT/mTOR-glycolysis signaling pathway, which establishes the rationale for targeting the TRIM59-related pathways to treat PC. 相似文献
220.
Wu Yanyan Tian Qinglan Huang Weihua Liu Jieyun Xia Xiuzhong Yang Xinghai Mou Haifei 《Molecular biology reports》2020,47(4):2951-2962
Molecular Biology Reports - Passion fruit (Passiflora edulis), an important tropical and subtropical fruit, has a high edible and medicinal value. Stem rot disease is one of the most important... 相似文献