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   6213篇
  免费   293篇
  国内免费   88篇
耳鼻咽喉   73篇
儿科学   71篇
妇产科学   132篇
基础医学   818篇
口腔科学   90篇
临床医学   497篇
内科学   1373篇
皮肤病学   96篇
神经病学   456篇
特种医学   472篇
外科学   859篇
综合类   25篇
预防医学   176篇
眼科学   66篇
药学   663篇
中国医学   93篇
肿瘤学   634篇
  2023年   43篇
  2022年   140篇
  2021年   214篇
  2020年   102篇
  2019年   149篇
  2018年   159篇
  2017年   142篇
  2016年   193篇
  2015年   257篇
  2014年   288篇
  2013年   344篇
  2012年   522篇
  2011年   511篇
  2010年   355篇
  2009年   240篇
  2008年   392篇
  2007年   368篇
  2006年   308篇
  2005年   291篇
  2004年   245篇
  2003年   206篇
  2002年   156篇
  2001年   141篇
  2000年   141篇
  1999年   108篇
  1998年   65篇
  1997年   49篇
  1996年   39篇
  1995年   31篇
  1994年   23篇
  1993年   19篇
  1992年   30篇
  1991年   34篇
  1990年   31篇
  1989年   29篇
  1988年   28篇
  1987年   28篇
  1986年   20篇
  1985年   25篇
  1984年   13篇
  1983年   12篇
  1981年   8篇
  1980年   13篇
  1979年   8篇
  1978年   6篇
  1974年   6篇
  1973年   7篇
  1971年   7篇
  1969年   7篇
  1968年   6篇
排序方式: 共有6594条查询结果,搜索用时 15 毫秒
81.
Cronobacter sakazakii is an opportunistic pathogen that causes neonatal meningitis and necrotizing enterocolitis. Its interaction with intestinal epithelium is important in the pathogenesis of enteric infections. In this study, we investigated the involvement of the inv gene in the virulence of C. sakazakii ATCC 29544 in vitro and in vivo. Sequence analysis of C. sakazakii ATCC 29544 inv revealed that it is different from other C. sakazakii isolates. In various cell culture models, an Δinv deletion mutant showed significantly lowered invasion efficiency, which was restored upon genetic complementation. Studying invasion potentials using tight-junction-disrupted Caco-2 cells suggested that the inv gene product mediates basolateral invasion of C. sakazakii ATCC 29544. In addition, comparison of invasion potentials of double mutant (ΔompA Δinv) and single mutants (ΔompA and Δinv) provided evidence for an additive effect of the two putative outer membrane proteins. Finally, the importance of inv and the additive effect of putative Inv and OmpA were also proven in an in vivo rat pup model. This report is the first to demonstrate two proteins working synergistically in vitro, as well as in vivo in C. sakazakii pathogenesis.  相似文献   
82.
Brillouin light scattering offers a unique label-free approach to measure biomechanical properties non-invasively. While this technique is used in biomechanical analysis of cells and tissues, its potential for visualizing structural features of tissues based on the biomechanical contrast has not been much exploited. Here, we present high-resolution Brillouin microscopy images of four basic tissue types: muscular, connective, epithelial, and nervous tissues. The Brillouin contrast distinguishes between muscle fiber cells and endomysium in skeletal muscle and reveals chondrocytes along with spatially varying stiffness of the extracellular matrix in articular cartilage. The hydration-sensitive contrast can visualize the stratum corneum, epidermis, and dermis in the skin epithelium. In brain tissues, the Brillouin images show the mechanical heterogeneity across the cortex and deeper regions. This work demonstrates the versatility of using the Brillouin shift as histological contrast for examining intact tissue substructures via longitudinal modulus without the need for laborious tissue processing steps.  相似文献   
83.
84.
Objective: To investigate the anti-colon cancer effects of ethylacetate fraction from Orostachys japonicus(0. japonicus) on HT-29 cancer cells. Methods: The viability of HT-29 cells was assayed by the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2 H-tetrazolium(MTS) method. Apoptosis induction and cell cycle inhibition were confirmed by fluorescein isothiocyanate and propidium iodide staining using flow cytometry.Morphological changes in the nucleus were observed, using a fluorescence microscope with4',6-diamidino-2-phenylindole(DAPI) nuclear staining. The expression levels of the upstream and downstream proteins involved in the anti-cancer mechanism were confirmed by Western blotting. Results: After treating HT-29 cells with different concentrations of ethylacetate fraction from O. japonicus, the viability of cells decreased in a concentration-dependent manner,while apoptosis induction and apoptotic body formation increased. Cell cycle analysis showed that the arrest occurred at the sub-G_1 and S phase. Among the upstream and downstream proteins involved in anti-cancer activity, the level of B cell lymphoma-2 decreased, and the bcl-2-associated x protein increased. The level of pro-caspase-3, pro-caspase-8, and pro-caspase-9 decreased, while the level of cleaved-caspase-3, cleaved-caspase-8, and cleaved-caspase-9 increased. Moreover, the phosphorylation, that is, activation of extracellular signal regulated kinase 1/2, Jun-N-terminal kinase, and p38 increased. Conclusions: Combining the above results, it is thought that the survival of HT-29 cells is suppressed by ethylacetate fraction from0. japonicus through mitochondrial regulation-induced caspase cascade activation, induction of apoptosis and cell cycle arrest.  相似文献   
85.
86.
There have been limited studies of subjective tongue function over long‐term follow‐up in spite of swallowing and articulation disorders are common complications of glossectomy. To assess long‐term subjective swallowing and articulation function after partial glossectomy. A total of 63 patients with the mobile tongue cancer who underwent partial glossectomy without reconstruction were interviewed to score their swallowing and articulation function on a 100‐point scale. The relation of this subjective scoring to the perioperative data was subjected to multivariate analysis. The mean patient age was 53·4 (19–81) years, and the mean follow‐up duration was 78·9 (14–277) months. Mean swallowing and articulation function score was 87·7 ± 6·1 and 88·6 ± 5·4. Age, follow‐up duration, T stage and resection volume were significantly correlated with swallowing function (= 0·026, 0·029, 0·016, 0·002, respectively); follow‐up duration was correlated with articulation function (= 0·039). Patients who undergo partial glossectomy without reconstruction generally demonstrate good function on long‐term follow‐up. Subjective dysfunction was correlated with larger resection volume, older age and shorter follow‐up duration.  相似文献   
87.
88.
The intra-arterial administration of nimodipine (IAN) is commonly used for cerebral vasospasm refractory to medical treatments. We report two cases of vasogenic edema after IAN. Our patients with aneurismal subarachnoid hemorrhage presented with vasospasm, which was treated by IAN. Consequently, vasogenic edema developed in the basal ganglia. Reperfusion following IAN for vasospasm may have the potential for inciting vasogenic edema in the ischemic brain.  相似文献   
89.
90.
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