首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   50422篇
  免费   3256篇
  国内免费   943篇
耳鼻咽喉   430篇
儿科学   1277篇
妇产科学   1355篇
基础医学   5605篇
口腔科学   866篇
临床医学   4321篇
内科学   11999篇
皮肤病学   790篇
神经病学   4837篇
特种医学   1854篇
外国民族医学   2篇
外科学   6871篇
综合类   2091篇
现状与发展   1篇
一般理论   3篇
预防医学   2521篇
眼科学   718篇
药学   4092篇
  8篇
中国医学   984篇
肿瘤学   3996篇
  2023年   468篇
  2022年   1175篇
  2021年   1834篇
  2020年   1149篇
  2019年   1226篇
  2018年   1399篇
  2017年   1146篇
  2016年   1209篇
  2015年   1497篇
  2014年   1956篇
  2013年   2423篇
  2012年   3212篇
  2011年   3199篇
  2010年   1934篇
  2009年   1785篇
  2008年   2713篇
  2007年   2722篇
  2006年   2512篇
  2005年   2398篇
  2004年   2174篇
  2003年   1895篇
  2002年   1718篇
  2001年   1467篇
  2000年   1389篇
  1999年   1297篇
  1998年   493篇
  1997年   363篇
  1996年   385篇
  1995年   313篇
  1994年   281篇
  1993年   229篇
  1992年   701篇
  1991年   607篇
  1990年   558篇
  1989年   571篇
  1988年   481篇
  1987年   432篇
  1986年   414篇
  1985年   331篇
  1984年   281篇
  1983年   224篇
  1982年   123篇
  1979年   220篇
  1978年   136篇
  1977年   117篇
  1974年   129篇
  1973年   127篇
  1972年   126篇
  1971年   112篇
  1969年   102篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
Recent epidemiological studies suggested that proton pump inhibitor (PPI) use was associated with an increased risk of biliary tract cancer (BTC), however, confounders were not adequately controlled. Our study aimed to evaluate PPI use and subsequent risk of BTC and its subtypes in three well-established cohorts. We conducted a pooled analysis of the subjects free of cancers in UK Biobank (n = 463 643), Nurses' Health Study (NHS, n = 80 235) and NHS II (n = 95 869). Propensity score weighted Cox models were used to estimate marginal HRs of PPIs use on BTC risk, accounting for potential confounders. We documented 284 BTC cases in UK Biobank (median follow-up: 7.6 years), and 91 cases in NHS and NHS II cohorts (median follow-up: 15.8 years). In UK biobank, PPI users had a 96% higher risk of BTC compared to nonusers in crude model (HR 1.96, 95% CI 1.44-2.66), but the effect was attenuated to null after adjusting for potential confounders (HR 0.95, 95% CI 0.60-1.49). PPI use was not associated with risk of BTC in the pooled analysis of three cohorts (HR 0.93, 95% CI 0.60-1.43). We also observed no associations between PPI use with risk of intrahepatic (HR 1.00, 95% CI 0.49-2.04), extrahepatic bile duct (HR 1.09, 95% CI 0.52-2.27) and gallbladder cancers (HR 0.66, 95% CI 0.26-1.66) in UK Biobank. In summary, regular use of PPIs was not associated with the risk of BTC and its subtypes.  相似文献   
3.
癫痫发作后状态(PIS)是指癫痫发作停止到恢复至发病前水平的异常状态,包括认知、运动、感觉、自主神经和精神行为等异常,症状多样,严重程度不一,持续数秒至数天不等,对患者的健康和生活质量产生很大影响。然而,目前国内外相关的研究较少,临床医生对此缺乏正确认识,容易误诊误治。本文将从PIS的定义、病理生理机制、临床表现、诊断和鉴别诊断、临床意义以及干预策略等进行综述,以提高临床医生的认识,并为今后临床研究提供参考。  相似文献   
4.
Introduction: Collaborative interactions between several diverse biological processes govern the onset and progression of breast cancer. These processes include alterations in cellular metabolism, anti-tumor immune responses, DNA damage repair, proliferation, anti-apoptotic signals, autophagy, epithelial-mesenchymal transition, components of the non-coding genome or onco-mIRs, cancer stem cells and cellular invasiveness. The last two decades have revealed that each of these processes are also directly regulated by a component of the cell cycle apparatus, cyclin D1.

Area covered: The current review is provided to update recent developments in the clinical application of cyclin/CDK inhibitors to breast cancer with a focus on the anti-tumor immune response.

Expert opinion: The cyclin D1 gene encodes the regulatory subunit of a proline-directed serine-threonine kinase that phosphorylates several substrates. CDKs possess phosphorylation site selectivity, with the phosphate-acceptor residue preceding a proline. Several important proteins are substrates including all three retinoblastoma proteins, NRF1, GCN5, and FOXM1. Over 280 cyclin D3/CDK6 substrates have b\een identified. Given the diversity of substrates for cyclin/CDKs, and the altered thresholds for substrate phosphorylation that occurs during the cell cycle, it is exciting that small molecular inhibitors targeting cyclin D/CDK activity have encouraging results in specific tumors.  相似文献   

5.
6.
To evaluate the changes in alveolar contour after guided bone regeneration (GBR) with two different combinations of biomaterials in dehiscence defects arou  相似文献   
7.
8.
9.
10.

Background

Rosacea is a chronic inflammatory skin condition whose etiology has been linked to mast cells and the antimicrobial peptide cathelicidin LL-37. Individuals with refractory disease have demonstrated clinical benefit with periodic injections of onabotulinum toxin, but the mechanism of action is unknown.

Objectives

To investigate the molecular mechanism by which botulinum toxin improves rosacea lesions.

Methods

Primary human and murine mast cells were pretreated with onabotulinum toxin A or B or control. Mast cell degranulation was evaluated by β-hexosaminidase activity. Expression of botulinum toxin receptor Sv2 was measured by qPCR. The presence of SNAP-25 and VAMP2 was established by immunofluorescence. In vivo rosacea model was established by intradermally injecting LL-37 with or without onabotulinum toxin A pretreatment. Mast cell degranulation was assessed in vivo by histologic counts. Rosacea biomarkers were analyzed by qPCR of mouse skin sections.

Results

Onabotulinum toxin A and B inhibited compound 48/80-induced degranulation of both human and murine mast cells. Expression of Sv2 was established in mouse mast cells. Onabotulinum toxin A and B increased cleaved SNAP-25 and decreased VAMP2 staining in mast cells respectively. In mice, injection of onabotulinum toxin A significantly reduced LL-37-induced skin erythema, mast cell degranulation, and mRNA expression of rosacea biomarkers.

Conclusions

These findings suggest that onabotulinum toxin reduces rosacea-associated skin inflammation by directly inhibiting mast cell degranulation. Periodic applications of onabotulinum toxin may be an effective therapy for refractory rosacea and deserves further study.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号