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   2787篇
  免费   165篇
  国内免费   14篇
耳鼻咽喉   52篇
儿科学   75篇
妇产科学   80篇
基础医学   381篇
口腔科学   52篇
临床医学   195篇
内科学   674篇
皮肤病学   161篇
神经病学   208篇
特种医学   119篇
外科学   223篇
综合类   7篇
一般理论   3篇
预防医学   154篇
眼科学   44篇
药学   263篇
中国医学   8篇
肿瘤学   267篇
  2024年   3篇
  2023年   35篇
  2022年   44篇
  2021年   100篇
  2020年   53篇
  2019年   74篇
  2018年   72篇
  2017年   75篇
  2016年   88篇
  2015年   85篇
  2014年   120篇
  2013年   140篇
  2012年   212篇
  2011年   233篇
  2010年   118篇
  2009年   126篇
  2008年   186篇
  2007年   199篇
  2006年   190篇
  2005年   162篇
  2004年   162篇
  2003年   154篇
  2002年   124篇
  2001年   25篇
  2000年   20篇
  1999年   25篇
  1998年   13篇
  1997年   13篇
  1996年   13篇
  1995年   15篇
  1994年   11篇
  1993年   6篇
  1992年   9篇
  1991年   13篇
  1990年   4篇
  1989年   7篇
  1988年   7篇
  1987年   5篇
  1986年   4篇
  1985年   3篇
  1976年   2篇
  1975年   2篇
  1974年   1篇
  1973年   1篇
  1968年   2篇
  1966年   2篇
  1943年   1篇
  1942年   1篇
  1931年   1篇
  1921年   1篇
排序方式: 共有2966条查询结果,搜索用时 15 毫秒
51.
BACKGROUND: Angiotensin II (AT) is implicated in the development of cardiac remodeling, which leads to heart failure, and pharmacological inhibition of the AT type 1 (AT1) receptor has improved mortality and morbidity in patients of heart failure. The aim of this study was to elucidate the role of the AT1 receptor in disease progression in muscle LIM protein (MLP)-deficient mice, which are susceptible to heart failure because of defective function of mechanosensors in cardiomyocytes. METHOD AND RESULTS: Hearts from MLP knockout (MLPKO) mice and MLP-AT1a receptor double knockout (DKO) mice were analyzed. MLPKO hearts showed marked chamber dilatation with cardiac fibrosis and reactivation of the fetal gene program. All of these changes were significantly milder in the DKO hearts. Impaired left ventricular (LV) contractility and filling were alleviated in DKO hearts. However, the impaired relaxation and downregulated expression of sarcoplasmic reticulum calcium-ATPase 2 were unchanged in DKO hearts. CONCLUSIONS: The AT1a receptor is involved in progression of LV remodeling and deterioration of cardiac function in the hearts of MLPKO mice. These results suggest that blockade of the receptor is effective in preventing progression of heart failure in dilated cardiomyopathy.  相似文献   
52.
53.
54.
This report illustrates successful nonsurgical orthodontic treatment of a hypodivergent adult patient with bilateral posterior scissors bite (Brodie bite) and excessive overjet. A 26-year-old woman primarily reported maxillary incisor protrusion. She was diagnosed with Class ll division 1 malocclusion with skeletal Class I, short face, low mandibular plane angle and bilateral posterior scissors bite. A lingual arch with anterior bite block and posterior miniscrews with preadjusted edgewise appliances were used to improve the bilateral scissors bite. After achieving molar occlusion, the maxillary first premolars were extracted, and six miniscrews were used to improve the anterior-posterior and vertical discrepancies. After active treatment for 56 months, the convex facial profile with excessively protruded lips was improved and good interdigitation with ideal incisor relationship was achieved. Additionally, the irregular movements of the incisal path and the bilateral condyles during lateral excursion were improved. At 13 months of retention, a satisfactory facial profile, occlusion, and jaw movements were maintained. The treatment results suggest that miniscrews and fixed bite blocks were effective and efficient to facilitate correction of the bilateral scissors bite, excessive overjet, and vertical relationship correction in this nonsurgical orthodontic treatment.  相似文献   
55.
56.
57.
58.
59.
Dorsoventral fibers in the presumptive dermis of the chick limb bud reported first by Hurle's group in 1989 are now revealed as bundles of fibrillin microfibrils (Isokawa et al., 2004). The bundles, which could be called oxytalan fibers at the light microscopic level, are aligned perpendicularly to the overlying ectoderm and form a unique fiber array, originating directly from the basal lamina. This well‐oriented organization is beneficial in examining the process of in vivo bundling of microfibrils into oxytalan fibers. In this study, sections through the presumptive limb dermis were preferentially prepared from chick embryos at Days 4–6 (ED4‐6). Immunohistochemically, fibrillin‐positive dots representing cross‐sectioned surfaces of individual fibers, increased in size from ED4 to 6, but their number per unit area remained constant. Ultrastructurally, a single oxytalan fiber at ED4 consisted of ~15 microfibrils; the latter number increased fourfold from ED4 to 5 and threefold from ED5 to 6. Oxytalan fibers were all closely associated with mesenchymal cell; notably, the fibers at ED5 and 6 were held in a shallow ditch on the cell body or by lamellipodial cytoplasmic protrusion. In the sites of cell–fiber adhesion, microfibrils in the periphery of an oxytalan fiber appeared to adhere directly or by means of short flocculent strands to a nearby cell membrane; the latter showed a thickening of plasmalemma and its undercoat, indicating the presence of adhesive membrane specification. These findings suggest that the bundling of microfibrils is a progressive and closely cell‐associated process. Anat Rec, 2013. © 2012 Wiley Periodicals, Inc.  相似文献   
60.
Here, we show that overexpression of fer tyrosine kinase (FER), a non-receptor tyrosine kinase, predicts poor postoperative outcome and might be involved in cancer-cell survival in non-small cell lung cancer (NSCLC). Systematic screening using in silico analyses and quantitative RT-PCR revealed that FER was overexpressed in about 10% of NSCLC patients. Evaluation of FER expression using immunohistochemistry (IHC) on tissue microarrays was consistent with the mRNA level detected using quantitative RT-PCR. In analyses of 135 NSCLC patients who had undergone potential curative resection, we found that FER overexpression detected using IHC had no association with clinicopathological features such as age, sex, smoking history, histological type, disease stage, T factor, N factor, adjuvant chemotherapy history, or EGFR mutation, but was correlated with poor postoperative survival periods. A multivariate Cox regression analysis showed that this prognostic impact was independent of other clinicopathological features. In functional analyses of FER in vitro, FER exhibited a transforming activity, suggesting that it possesses oncogenic functions. We also found that human lung cancer NCI-H661 cells, which exhibited FER-outlier expression, were led to apoptosis by the knockdown of FER using RNA interference. FER overexpression might serve as a prognostic biomarker and be involved in cancer-cell survival in NSCLC.  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