全文获取类型
收费全文 | 22187篇 |
免费 | 1961篇 |
国内免费 | 2584篇 |
专业分类
26732篇 |
出版年
2024年 | 61篇 |
2023年 | 219篇 |
2022年 | 557篇 |
2021年 | 888篇 |
2020年 | 758篇 |
2019年 | 897篇 |
2018年 | 857篇 |
2017年 | 701篇 |
2016年 | 828篇 |
2015年 | 1293篇 |
2014年 | 1634篇 |
2013年 | 1765篇 |
2012年 | 2115篇 |
2011年 | 1965篇 |
2010年 | 1312篇 |
2009年 | 1162篇 |
2008年 | 1529篇 |
2007年 | 1289篇 |
2006年 | 1191篇 |
2005年 | 991篇 |
2004年 | 979篇 |
2003年 | 904篇 |
2002年 | 811篇 |
2001年 | 366篇 |
2000年 | 263篇 |
1999年 | 215篇 |
1998年 | 218篇 |
1997年 | 132篇 |
1996年 | 129篇 |
1995年 | 130篇 |
1994年 | 94篇 |
1993年 | 77篇 |
1992年 | 64篇 |
1991年 | 46篇 |
1990年 | 31篇 |
1989年 | 44篇 |
1988年 | 28篇 |
1987年 | 27篇 |
1986年 | 28篇 |
1985年 | 25篇 |
1984年 | 7篇 |
1983年 | 10篇 |
1982年 | 18篇 |
1981年 | 5篇 |
1977年 | 5篇 |
1969年 | 4篇 |
1967年 | 4篇 |
1965年 | 4篇 |
1963年 | 3篇 |
1962年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Nishida O Kuwazaki S Suzuki C Shima J 《Bioscience, biotechnology, and biochemistry》2004,68(7):1442-1448
Yeast strains were isolated from dried sweet potatoes (hoshi-imo), a traditional preserved food in Japan. Dough fermentation ability, freeze tolerance, and growth rates in molasses, which are important characteristics of commercial baker's yeast, were compared between these yeast strains and a commercial yeast derivative that had typical characteristics of commercial strains. Classification tests including pulse-field gel electrophoresis and fermentation/assimilation ability of sugars showed that almost the stains isolated belonged to Saccharomyces cerevisiae. One strain, ONY1, accumulated intracellular trehalose at a higher level than commercial strain T128. Correlated with intracellular trehalose contents, the fermentation ability of high-sugar dough containing ONY1 was higher. ONY1 also showed higher freeze tolerance in both low-sugar and high-sugar doughs. The growth rate of ONY1 was significantly higher under batch and fed-batch cultivation conditions using either molasses or synthetic medium than that of strain T128. These results suggest that ONY1 has potential commercial use as baker's yeast for frozen dough and high-sugar dough. 相似文献
62.
Wang J Zhao W Cheng L Guo M Li D Li X Tan Y Ma S Li S Yang Y Chen L Wang S 《Journal of immunology (Baltimore, Md. : 1950)》2010,185(12):7654-7662
Chronic hepatitis B virus (HBV) infection is characterized by sustained liver inflammation with an influx of lymphocytes, which contributes to the development of cirrhosis and hepatocellular carcinoma. The mechanisms underlying this immune-mediated hepatic pathogenesis remain ill defined. We report in this article that repetitive infusion of anti-CD137 agonist mAb in HBV-transgenic mice closely mimics this process by sequentially inducing hepatitis, fibrosis, cirrhosis, and, ultimately, liver cancer. CD137 mAb initially triggers hepatic inflammatory infiltration due to activation of nonspecific CD8(+) T cells with memory phenotype. CD8(+) T cell-derived IFN-γ plays a central role in the progression of chronic liver diseases by actively recruiting hepatic macrophages to produce fibrosis-promoting cytokines and chemokines, including TNF-α, IL-6, and MCP-1. Importantly, the natural ligand of CD137 was upregulated significantly in circulating CD14(+) monocytes in patients with chronic hepatitis B infection and closely correlated with development of liver cirrhosis. Thus, sustained CD137 stimulation may be a contributing factor for liver immunopathology in chronic HBV infection. Our studies reveal a common molecular pathway that is used to defend against viral infection but also causes chronic hepatic diseases. 相似文献
63.
MAPping Kinase Regulation of ICE1 in Freezing Tolerance 总被引:1,自引:0,他引:1
64.
65.
66.
67.
随着分子生物信息数据量高速增长,生物信息学面临着大规模、高通量、密集型计算的巨大挑战。为有效利用计算机资源,缩短高通量生物信息计算程序执行时间,我们基于Globus Toolkit网格中间件,实现了一个支持高通量生物数据计算的网格系统(Biological Data Computing Grid,简称BDCGrid)。BDCGrid计算网格系统模型可以有效整合中小型生物信息学实验室计算机资源,大大缩短高通量生物信息计算程序执行时间,为相关研究人员利用现有计算机资源处理大规模、高通量生物信息计算任务提供一种新的途径。 相似文献
68.
Sunkyung Lee Kyu Yang Yi Sung Jun Youn Byung Ho Lee Sung-eun Yoo 《Bioorganic & medicinal chemistry letters》2009,19(5):1329-1331
A series of (2-aryl-5-methylimidazol-4-ylcarbonyl)guanidines and (2-aryl-5-methyloxazol-4-ylcarbonyl)guanidines were synthesized and evaluated as NHE-1 inhibitors. The structure–activity relationships well matched those of furan derivatives, which were previously investigated. The (2,5-disubstituted)phenyl compounds showed better activities than the other analogues in both imidazole and oxazole compounds. Especially, 2-(2,5-dichlorophenyl)imidazole 52, and 2-(2-methoxy-5-chlorophenyl)imidazole 54 compounds exhibited potent cardioprotective efficacy both in vitro and in vivo as well as high NHE-1 inhibitory activities. 相似文献
69.
Background and Objective
Emerging evidence indicates that common functional polymorphisms in the estrogen receptor 1 (ESR1) gene may have an impact on an individual’s susceptibility to endometrial cancer, but individually published results are inconclusive. The aim of this meta-analysis is to derive a more precise estimation of the associations between eight polymorphisms in the ESR1 gene and endometrial cancer risk.Methods
A literature search of PubMed, Embase, Web of Science and China Biology Medicine (CBM) databases was conducted on publications published before November 1st, 2012. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. Statistical analyses were performed using the STATA 12.0 software.Results
Thirteen case-control studies were included with a total of 7,649 endometrial cancer cases and 16,855 healthy controls. When all the eligible studies were pooled into the meta-analysis, the results indicated that PvuII (C>T) polymorphism was associated with an increased risk of endometrial cancer, especially among Caucasian populations. There were also significant associations between rs3020314 (C>T) polymorphism and an increased risk of endometrial cancer. Furthermore, rs2234670 (S/L) polymorphism may decrease the risk of endometrial cancer. However, no statistically significant associations were found in XbaI (A>G), Codon 325 (C>G), Codon 243 (C>T), VNTR (S/L) and rs2046210 (G>A) polymorphisms.Conclusion
The current meta-analysis suggests that PvuII (C>T) and rs3020314 (C>T) polymorphisms may be risk factors for endometrial cancer, especially among Caucasian populations. 相似文献70.
The dysregulation of miR-137 plays vital roles in the oncogenesis and progression of various types of cancer, but its role in prognosis of gastric cancer patients remains unknown. This study was designed to investigate the expression and prognostic significance of miR-137 in gastric cancer patients after radical gastrectomy. Quantitative real-time PCR (qRT-PCR) was performed to evaluate the expression of miR-137 in human gastric cancer cell lines and tissues in patients with gastric adenocarcinoma. Results were assessed for association with clinical factors and overall survival by using Kaplan-Meier analysis. Prognostic values of miR-137 expression and clinical outcomes were evaluated by Cox regression analysis. The results exhibited that the expression level of miR-137 was decreased in human gastric cancer cell lines and tissues, and down-regulated expression of miR-137 was associated with tumor cell differentiation, N stage, and TNM stage. Decreased miR-137 expression in gastric cancer tissues was positively correlated with poor overall survival of gastric cancer patients. Further multivariate Cox regression analysis suggested that miR-137 expression was an independent prognostic indicator for gastric cancer except for TNM stage. Applying the prognostic value of miR-137 expression to TNM stage III group showed a better risk stratification for overall survival. In conclusion, the results reinforced the critical role for the down-regulated miR-137 expression in gastric cancer and suggested that miR-137 expression could be a prognostic indicator for this disease. In addition, these patients with TNM stage III gastric cancer and low miR-137 expression might need more aggressive postoperative treatment and closer follow-up. 相似文献