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   6791篇
  免费   446篇
  国内免费   191篇
耳鼻咽喉   48篇
儿科学   80篇
妇产科学   45篇
基础医学   1013篇
口腔科学   131篇
临床医学   354篇
内科学   775篇
皮肤病学   151篇
神经病学   199篇
特种医学   89篇
外科学   2141篇
综合类   770篇
现状与发展   1篇
预防医学   277篇
眼科学   162篇
药学   410篇
中国医学   148篇
肿瘤学   634篇
  2024年   11篇
  2023年   65篇
  2022年   137篇
  2021年   211篇
  2020年   170篇
  2019年   240篇
  2018年   242篇
  2017年   213篇
  2016年   163篇
  2015年   195篇
  2014年   397篇
  2013年   335篇
  2012年   264篇
  2011年   469篇
  2010年   376篇
  2009年   415篇
  2008年   382篇
  2007年   411篇
  2006年   416篇
  2005年   354篇
  2004年   418篇
  2003年   295篇
  2002年   235篇
  2001年   165篇
  2000年   133篇
  1999年   147篇
  1998年   100篇
  1997年   100篇
  1996年   64篇
  1995年   54篇
  1994年   34篇
  1993年   40篇
  1992年   16篇
  1991年   25篇
  1990年   8篇
  1989年   5篇
  1987年   5篇
  1986年   8篇
  1985年   18篇
  1984年   13篇
  1983年   11篇
  1982年   7篇
  1981年   7篇
  1980年   10篇
  1979年   18篇
  1978年   6篇
  1977年   6篇
  1976年   3篇
  1975年   4篇
  1973年   2篇
排序方式: 共有7428条查询结果,搜索用时 13 毫秒
91.
目的 探讨重型颅脑损伤后早期血清白细胞介素-17(IL-17)、白细胞介素-23(IL-23)、乳酸(Lac)水平变化及对继发性大面积脑梗死的预测价值.方法 选取2017年9月—2020年9月新华医院崇明分院收治的158例重型颅脑损伤患者为研究组,另选同期来院体检的146例健康体检者,为对照组.比较两组血清IL-17、...  相似文献   
92.
93.
An in vitro angiogenesis system was designed for screening angiogenic agonists and antagonists. In order to obtain large quantities of cells and reproducibility, human endothelial cells with extended life spans were developed by retroviral transfection. The resulting cells grown in a serum-free medium containing endothelial cell growth supplement (ECGS) have a telomerase activity, extended life spans of at least 21 passages, and an endothelial cell phenotype (diI-acetylated-LDL upake, factor VIII-related antigen, VEGFR-1 and R-2, and tissue-type plasminogen activator (tPA)) that resembled that of unaltered primary endothelial cells. Exceptions were (i) a higher expression of tPA, and (ii) a non-significant growth response to FGF-2 or VEGF stimulation. Within three-dimensional fibrin gels, specific cell clones rapidly formed tubular structures in a more reproducible manner than those observed with low-passage primary cells. Tube formation by primary endothelial cells and those with extended life spans was dependent upon FGF-2 and ECGS, respectively. Both cell types produced FGF-2 and VEGF cytokines. Increasing doses of suramin significantly decreased the size of microvessels formed by both cell lines. These functional results indicate that a vascular matrix system containing human cells with extended life spans can be successfully utilized as an in vitro assay for antiangiogenic compounds.  相似文献   
94.
95.
Fibroblast growth factors (FGFs) exert autocrine/paracrine functions in prostate cancer by stimulating angiogenesis and tumour growth. Here dihydrotestosterone (DHT) up‐regulates FGF2 and FGF8b production in murine TRAMP‐C2 prostate cancer cells, activating a FGF‐dependent autocrine loop of stimulation. The soluble pattern recognition receptor long pentraxin‐3 (PTX3) acts as a natural FGF antagonist that binds FGF2 and FGF8b via its N‐terminal domain. We demonstrate that recombinant PTX3 protein and the PTX3‐derived pentapeptide Ac‐ARPCA‐NH2 abolish the mitogenic response of murine TRAMP‐C2 cells and human LNCaP prostate cancer cells to DHT and FGFs. Also, PTX3 hampers the angiogenic activity of DHT‐activated TRAMP‐C2 cells on the chick embryo chorioallantoic membrane (CAM). Accordingly, human PTX3 overexpression inhibits the mitogenic activity exerted by DHT or FGFs on hPTX3_TRAMP‐C2 cell transfectants and their angiogenic activity. Also, hPTX3_TRAMP‐C2 cells show a dramatic decrease of their angiogenic and tumourigenic potential when grafted in syngeneic or immunodeficient athymic male mice. A similar inhibitory effect is observed when TRAMP‐C2 cells overexpress only the FGF‐binding N‐terminal PTX3 domain. In keeping with the anti‐tumour activity of PTX3 in experimental prostate cancer, immunohistochemical analysis of prostate needle biopsies from primary prostate adenocarcinoma patients shows that parenchymal PTX3 expression, abundant in basal cells of normal glands, is lost in high‐grade prostatic intraepithelial neoplasia and in invasive tumour areas. These results identify PTX3 as a potent FGF antagonist endowed with anti‐angiogenic and anti‐neoplastic activity in prostate cancer. Copyright © 2013 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.  相似文献   
96.
97.
Abstract

The expression and synthesis of acidic and basic fibroblast growth factors (aFGF and bFGF) in cultures of bovine and human vascular smooth muscle cells (BSMC and HSMC) was studied. BSMC express and synthesize only bFGF, whereas HSMC express and synthesize both bFGF and aFGF. The presence of bFGF in BSMC is shown by the following criteria: (1) the growth factor activity in BSMC lysates binds to a heparin-affinity column and elutes as a single peak at 1.5-1.7 m NaCl, characteristic for bFGF; (2) this extract is mitogenic for smooth muscle cells; (3) Northern blot analysis demonstrates three distinct bFGF mRNAs of 7.0, 4.0, and 1.9 kb; no aFGF mRNA species were detected. Analysis of human umbilical vein endothelial cells yielded similar results: Heparin-affinity chromatography and Northern blot analysis failed to demonstrate the presence of aFGF despite the detection of bFGF by these techniques. In contrast, HSMC synthesize two growth factor activities: First, they bind to an immobilized heparin column and elute as two separate peaks at 1.2 and 1.5-1.7 m NaCl, characteristic for aFGF and bFGF; and second, Northern blot analysis demonstrates the expression of aFGF mRNA of 4.6 kb and bFGF mRNAs of 7.0, 4.0 and 1.9 kb. Furthermore, it is shown that aFGF and bFGF are potent mitogens for smooth muscle cells in vitro.  相似文献   
98.
99.
Levels of serum phosphate are controlled by the peptide hormone FGF23, secreted from bone osteocytes. Elevated levels of circulating FGF23 are a key factor in several hypophosphatemic disorders and play a role in chronic kidney disease. Posttranslational processing of FGF23 includes multi‐site O‐glycosylation, which reduces intracellular cleavage by proprotein convertases. The FGF23 protein also contains four serine phosphorylation consensus sequences (S‐X‐D/E); in this work, we asked whether FGF23 is a substrate for secretory phosphorylation. Both HEK cells as well as IDG‐SW3 cells, an osteocyte model, incorporated radiolabeled orthophosphate into intact FGF23, as well as into the 14‐kDa carboxy‐terminal—but not the 17‐kDa N‐terminal—fragment. Sequential serine‐to‐alanine site‐directed mutagenesis of four kinase consensus sites showed that labeling occurred on three serines within the carboxy‐terminal fragment, Ser180 (adjacent to the cleavage site), Ser207, and Ser212. Liquid chromatography‐coupled mass spectroscopy indicated the presence of phosphate at Ser212 in recombinant R&D mouse FGF23R179Q, confirming labeling results. A phosphopeptide‐specific antibody was raised against phospho‐Ser212 and exhibited immunoreactivity in osteocytes present in mouse long bone, providing further evidence that FGF23 is naturally phosphorylated in bone. Bone SIBLING proteins are serine‐phosphorylated by the ubiquitous Golgi secretory kinase FAM20C. Cotransfection of HEK and MC3T3 cells with FGF23 and active, but not inactive, FAM20C kinase increased the storage and release of FGF23 in radiolabeling experiments, indicating potential effects of phosphorylation on FGF23 stability. Collectively, these data point to an important role for phosphorylation of FGF23 in bone. © 2014 American Society for Bone and Mineral Research.  相似文献   
100.
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