全文获取类型
收费全文 | 4457篇 |
免费 | 381篇 |
国内免费 | 282篇 |
专业分类
5120篇 |
出版年
2024年 | 11篇 |
2023年 | 48篇 |
2022年 | 137篇 |
2021年 | 237篇 |
2020年 | 167篇 |
2019年 | 188篇 |
2018年 | 205篇 |
2017年 | 137篇 |
2016年 | 185篇 |
2015年 | 291篇 |
2014年 | 359篇 |
2013年 | 335篇 |
2012年 | 416篇 |
2011年 | 350篇 |
2010年 | 212篇 |
2009年 | 223篇 |
2008年 | 251篇 |
2007年 | 198篇 |
2006年 | 161篇 |
2005年 | 134篇 |
2004年 | 109篇 |
2003年 | 119篇 |
2002年 | 111篇 |
2001年 | 80篇 |
2000年 | 72篇 |
1999年 | 52篇 |
1998年 | 27篇 |
1997年 | 36篇 |
1996年 | 37篇 |
1995年 | 43篇 |
1994年 | 33篇 |
1993年 | 24篇 |
1992年 | 28篇 |
1991年 | 22篇 |
1990年 | 18篇 |
1989年 | 15篇 |
1988年 | 8篇 |
1987年 | 8篇 |
1986年 | 10篇 |
1985年 | 3篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有5120条查询结果,搜索用时 0 毫秒
21.
Zhou XM Shao SJ Xu GD Zhong RT Liu DY Tang JW Gao YN Cheng SJ Lin BC 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2005,816(1-2):145-151
The p16 tumor suppressor gene is inactivated by promoter region hypermethylation in many types of tumor. Recent studies showed that aberrant methylation of the p16 gene is an early event in many tumors, especially in lung cancer, and may constitute a new biomarker for early detection and monitoring of prevention trials. We detected tumor-associated aberrant hypermethylation of the p16 gene in plasma and tissue DNA from 153 specimens using a modified semi-nested methylation-specific PCR (MSP) combining plastic microchip electrophoresis or slab gel electrophoresis, respectively. Specimens were from 79 lung cancer patients, 15 abdominal tumor patients, 30 positive controls and 30 negative controls. The results showed that the positive rate obtained by microchip electrophoresis was more than 26.6% higher and the same specificity was kept when compared with slab gel electrophoresis. The microchip electrophoresis can rapidly and accurately analyze the PCR products of methylated DNA and obviously improve the positive rate of diagnosis of cancer patients when compared with gel electrophoresis. This method with the high assay sensitivity might be used for detection of methylation of p16 gene and even to facilitate early diagnosis of cancer patients. 相似文献
22.
23.
AbstractThe aim of this paper is to develop a simulation-aided PROMETHEE-TOPSIS approach for the selection of the most desirable groundwater remediation strategies. The combination methods enables a careful evaluation of the identified remediation alternatives in which their strong and weak points can be detected and a ranking is provided which facilitates the final selection for the decision-maker. The capabilities and effectiveness of the developed method are illustrated through a case study on the remedial alternative selection for a naphthalene contaminated site in Anhui, China. Four attributes (i.e., total pumping rate, total cost, mean residual contaminant concentration and maximum excess life time cancer risk) for fifty remedial alternatives in each duration are considered and analytic hierarchy process is used to determine the weight of attributes importance. The results demonstrates that the developed method could help decision makers obtain the useful ranking information strategies that covering a variety of decision-relevant remediation options, which is beneficial for public health and environmental protection. 相似文献
24.
25.
26.
Background: Triple-negative breast cancer (TNBC) is a refractory subtype of breast cancer, 25–30% of which have dysregulation in the PI3K/AKT pathway. The present study investigated the anticancer effect of erianin on TNBC cell line and its underlying mechanism.Methods: After treatment with erianin, MTT assay was employed to determine the MDA-MB-231 and EFM-192A cell proliferation, the nucleus morphological changes were observed by DAPI staining. The cell cycle and apoptotic proportion were detected by flow cytometry. Western blot was performed to determine the cell cycle and apoptosis-related protein expression and PI3K pathways. Finally, the antiproliferative activity of erianin was further confirmed by adding or not adding PI3K agonists SC79.Results: Erianin inhibited the proliferation of MDA-MB-231 and EFM-192A cells in a dose-dependent manner, the IC50 were 70.96 and 78.58 nM, respectively. Erianin could cause cell cycle arrest at the G2/M phase, and the expressions of p21 and p27 were up-regulated, while the expressions of CDK1 and Cyclin B1 were down-regulated. Erianin also induced apoptosis via the mitochondrial pathway, with the up-regulation of the expression of Cyto C, PARP, Bax, active form of Caspase-3, and Caspase-9. Furthermore, p-PI3K and p-Akt expression were down-regulated by erianin. After co-incubation with SC79, the cell inhibition rate of erianin was decreased, which further confirmed that the attenuated PI3K/Akt pathway was relevant to the pro-apoptotic effect of erianin.Conclusions: Erianin can inhibit the proliferation of TNBC cells and induce cell cycle arrest and apoptosis, which may ascribe to the abolish the activation of the PI3K/Akt pathway. 相似文献
27.
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
28.
29.
30.