全文获取类型
收费全文 | 69946篇 |
免费 | 1971篇 |
国内免费 | 4734篇 |
学科分类
医药卫生 | 76651篇 |
出版年
2023年 | 237篇 |
2022年 | 414篇 |
2021年 | 304篇 |
2020年 | 243篇 |
2019年 | 722篇 |
2018年 | 862篇 |
2017年 | 378篇 |
2016年 | 472篇 |
2015年 | 572篇 |
2014年 | 1674篇 |
2013年 | 877篇 |
2012年 | 4250篇 |
2011年 | 4439篇 |
2010年 | 1296篇 |
2009年 | 1097篇 |
2008年 | 3659篇 |
2007年 | 4328篇 |
2006年 | 9379篇 |
2005年 | 10139篇 |
2004年 | 3841篇 |
2003年 | 4310篇 |
2002年 | 3394篇 |
2001年 | 3146篇 |
2000年 | 2702篇 |
1999年 | 1465篇 |
1998年 | 669篇 |
1997年 | 498篇 |
1996年 | 468篇 |
1995年 | 702篇 |
1994年 | 444篇 |
1993年 | 498篇 |
1992年 | 406篇 |
1991年 | 453篇 |
1990年 | 390篇 |
1989年 | 776篇 |
1988年 | 681篇 |
1987年 | 710篇 |
1986年 | 523篇 |
1985年 | 655篇 |
1984年 | 634篇 |
1983年 | 555篇 |
1982年 | 442篇 |
1981年 | 373篇 |
1980年 | 273篇 |
1979年 | 170篇 |
1959年 | 164篇 |
1958年 | 238篇 |
1957年 | 227篇 |
1956年 | 130篇 |
1955年 | 164篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
正目的非增强CT常常观察到心肌脂肪,但对其认识不足,本文旨在探究心肌内脂肪与全因死亡率的关系,无论是否有心肌梗死病史。方法本回顾性队列研究收集了不 相似文献
2.
目的观察下调FAM111B对宫颈癌细胞系C-33A和HeLa增殖、细胞周期和凋亡的影响及其可能机制。方法应用慢病毒载体siRNA-FAM111B及Null,分别感染C-33A和HeLa细胞。实时定量PCR方法(qRTPCR)和Western blot方法分别检查各组细胞FAM111B基因与蛋白的表达。应用CCK-8方法检测FAM111B对细胞增殖能力的影响。流式细胞术PI染色细胞周期检测各组细胞周期变化。流式细胞术Annexin V/PI双染方法检测各组细胞的凋亡情况。Western blot法检测p53及下游Bax和Bcl-2的表达。结果成功转染C-33A和HeLa细胞,FAM111B基因与蛋白表达水平均下调。转染siR-FAM111B能抑制宫颈癌细胞的增殖,C-33A和HeLa细胞发生G1期阻滞。下调FAM111B诱导宫颈癌细胞凋亡,促进p53蛋白表达,进而上调Bax蛋白和下调Bcl-2蛋白的表达。结论下调FAM111B抑制宫颈癌细胞的增殖,促使细胞周期G1期阻滞,诱导细胞凋亡,与调节p53蛋白进而激活下游相关信号通路相关。 相似文献
3.
正摘要虽然乳腺癌的发病率和死亡率随着年龄的增长而增加,但有关老年妇女筛查乳腺X线检查的益处和风险,以及老年妇女二维数字乳腺X线摄影(DM)和数字乳腺断层成 相似文献
4.
Arsen Osipov Alex B.Blair Juliane Liberto Jianxin Wang Keyu Li Brian Herbst Yao Xu Shiqi Li Nan Niu Rufiaat Rashid Ding Ding Yanan Liu Zaiqi Wang Christopher L.Wolfgang Richard A.Burkhart Daniel Laheru Lei Zheng 《癌症生物学与医学(英文版)》2021,(1):206-214
Objective:Pancreatic ductal adenocarcinoma(PDAC)is a deadly malignancy,due in large part to its resistance to conventional therapies,including radiotherapy(RT).Despite RT exerting a modest antitumor response,it has also been shown to promote an immunosuppressive tumor microenvironment.Previous studies demonstrated that focal adhesion kinase inhibitors(FAKi)in clinical development inhibit the infiltration of suppressive myeloid cells and T regulatory(T regs)cells,and subsequently enhance effector T cell infiltration.FAK inhibitors in clinical development have not been investigated in combination with RT in preclinical murine models or clinical studies.Thus,we investigated the impact of FAK inhibition on RT,its potential as an RT sensitizer and immunomodulator in a murine model of PDAC.Methods:We used a syngeneic orthotopic murine model to study the effect of FAKi on hypofractionated RT.Results:In this study we showed that IN10018,a small molecular FAKi,enhanced antitumor response to RT.Antitumor activity of the combination of FAKi and RT is T cell dependent.FAKi in combination with RT enhanced CD8+T cell infiltration significantly in comparison to the radiation or FAKi treatment alone(P<0.05).FAKi in combination with radiation inhibited the infiltration of granulocytes but enhanced the infiltration of macrophages and T regs in comparison with the radiation or FAKi treatment alone(P<0.01).Conclusions:These results support the clinical development of FAKi as a radiosensitizer for PDAC and combining FAKi with RT to prime the tumor microenvironment of PDAC for immunotherapy. 相似文献
5.
The ocular surface is covered by an epithelium encompassing an area including the cornea,the limbus and the conjunctiva bordered by the upper and lower lids.The healthy state of the ocular surface epithelium depends on a stable and protective preocular tear film when the eye is open.A stable preocular tear film is governed by sound ocular surface defense that involves effective neuroanatomic integration of compositional and hydrodynamic factors by two neural reflexes (1). 相似文献
6.
Andreas Marx Lena Koopmann Doris Hoflmayer Franziska Büscheck Claudia Hube-Magg Stefan Steurer Till Eichenauer Till S.Clauditz Waldemar Wilczak Ronald Simon Guido Sauter Jakob R.Izbicki Hartwig Huland Hans Heinzer Markus Graefen Alexander Haese Thorsten Schlomm Christian Bernreuther Patrick Lebok Sarah Bonk 《癌症生物学与医学(英文版)》2021,(1):245-255
Objective:Anoctamin 7(ANO7)is a calcium2+-dependent chloride ion channel protein.Its expression is restricted to prostate epithelial cells.The exact function is unknown.This study aimed to analyze ANO7 expression and its clinical significance in prostate cancer(PCa).Methods:ANO7 expression was assessed by immunohistochemistry in 17,747 clinical PCa specimens.Results:ANO7 was strongly expressed in normal prostate glandular cells but often less abundant in cancer cells.ANO7 staining was interpretable in 13,594 cancer tissues and considered strong in 34.4%,moderate in 48.7%,weak in 9.3%,and negative in 7.6%.Reduced staining was tightly linked to adverse tumor features[high classical and quantitative Gleason grade,lymph node metastasis,advanced tumor stage,high Ki67 labeling index,positive surgical margin,and early biochemical recurrence(P<0.0001 each)].The univariate Cox hazard ratio for prostate-specific antigen(PSA)recurrence after prostatectomy in patients with negative vs.strong ANO7 expression was 2.98(95%confidence interval 2.61–3.38).The prognostic impact was independent of established pre-or postoperatively available parameters(P<0.0001).Analysis of annotated molecular data showed that low ANO7 expression was linked to TMPRSS2:ERG fusions(P<0.0001),elevated androgen receptor expression(P<0.0001),as well as presence of 9 of 11 chromosomal deletions(P<0.05 each).A particularly strong association of low ANO7 expression with phosphatase and tensin homolog(PTEN)deletion may indicate a functional relationship with the PTEN/AKT pathway.Conclusions:These data identify reduced ANO7 protein expression as a strong and independent predictor of poor prognosis in PCa.ANO7 measurement,either alone or in combination,might provide clinically useful prognostic information in PCa. 相似文献
7.
<正>Glial cells play a key role during nervous system development and actively participate in all the cellular processes involved in maintaining its structural robustness and functional plasticity.In response to neuronal damage,glial cells proliferate,migrate to the injured region and change their morphology,function,and behavior 相似文献
8.
TWIK-related potassium channels(TREK) belong to a subfamily of the two-pore domain potassium channels family with three members, TREK1, TREK2 and TWIK-related arachidonic acid-activated potassium channels. The two-pore domain potassium channels is the last big family of channels being discovered, therefore it is not surprising that most of the information we know about TREK channels predominantly comes from the study of heterologously expressed channels. Notwithstanding, in this review we pay special attention to the limited amount of information available on native TREK-like channels and real neurons in relation to neuroprotection. Mainly we focus on the role of free fatty acids, lysophospholipids and other neuroprotective agents like riluzole in the modulation of TREK channels, emphasizing on how important this modulation may be for the development of new therapies against neuropathic pain, depression, schizophrenia, epilepsy, ischemia and cardiac complications. 相似文献
9.
10.