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   131204篇
  免费   11898篇
  国内免费   6489篇
耳鼻咽喉   1237篇
儿科学   2014篇
妇产科学   2939篇
基础医学   13739篇
口腔科学   2725篇
临床医学   16251篇
内科学   20473篇
皮肤病学   1615篇
神经病学   6542篇
特种医学   4301篇
外国民族医学   40篇
外科学   13592篇
综合类   19704篇
现状与发展   20篇
一般理论   18篇
预防医学   9581篇
眼科学   3499篇
药学   13570篇
  143篇
中国医学   6821篇
肿瘤学   10767篇
  2024年   1407篇
  2023年   2200篇
  2022年   4202篇
  2021年   5591篇
  2020年   4304篇
  2019年   3752篇
  2018年   3978篇
  2017年   3749篇
  2016年   3355篇
  2015年   5282篇
  2014年   6773篇
  2013年   6986篇
  2012年   10143篇
  2011年   10890篇
  2010年   7505篇
  2009年   6185篇
  2008年   7805篇
  2007年   7746篇
  2006年   7329篇
  2005年   6697篇
  2004年   4850篇
  2003年   4410篇
  2002年   3654篇
  2001年   3095篇
  2000年   2857篇
  1999年   2661篇
  1998年   1347篇
  1997年   1239篇
  1996年   1010篇
  1995年   959篇
  1994年   905篇
  1993年   518篇
  1992年   892篇
  1991年   806篇
  1990年   671篇
  1989年   574篇
  1988年   532篇
  1987年   451篇
  1986年   360篇
  1985年   291篇
  1984年   191篇
  1983年   168篇
  1982年   98篇
  1981年   95篇
  1980年   75篇
  1979年   141篇
  1978年   115篇
  1977年   88篇
  1974年   94篇
  1972年   87篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Angiolipoma of the tongue: report of a case   总被引:1,自引:0,他引:1  
Angiolipoma is a rare variety of lipoma in the maxillofacial region. Only eight cases have been documented so far. A case in which an angiolipoma occurred within the tongue of a 49-year-old man is described here. The difference from earlier cases occurring in the tongue is noted. Close follow-up has, as yet, revealed no recurrence.  相似文献   
42.
舌大小与开He相关性的研究   总被引:6,自引:0,他引:6  
目的 研究舌大小与开He之间的关系。方法 采用B型超声成像方法分别测量正常He与开He患者的舌大小,通过牙He与正常He舌大小的比较,研究舌大小与开He的相关性。结果 开He患者的舌大小测量结果均值大于正常He者,而且这种差别有显著的统计学意义。结论 与正常He者比较,开He患者存在舌过大的特性。  相似文献   
43.
44.
New emphasis in the treatment of dental trauma: avulsion and luxation   总被引:2,自引:0,他引:2  
There are several protocols for the successful management of dental trauma emergencies. However, these existing protocols are inconsistent regarding several issues. As the Israeli dental community and patients have specific characteristics, a modified and adaptable protocol was required. This new protocol contains simple and straightforward clinical guidelines, arranged in table format, according to the nature of the trauma. The present study shows the protocol for luxation and avulsion injuries, with new recommendations for the treatment of luxated closed-apex teeth, the preferred at-site treatment and storage medium for avulsed teeth, and the conditioning of the root surface in these cases. To emphasize and explain the modification of this new protocol, research-based information has been incorporated.  相似文献   
45.
46.
Amelogenesis imperfecta (AI) is a heterogeneous group of inherited defects in dental enamel formation. The malformed enamel can be unusually thin, soft, rough and stained. The strict definition of AI includes only those cases where enamel defects occur in the absence of other symptoms. Currently, there are seven candidate genes for AI: amelogenin, enamelin, ameloblastin, tuftelin, distal-less homeobox 3, enamelysin, and kallikrein 4. To identify sequence variations in AI candidate genes in patients with isolated enamel defects, and to deduce the likely effect of each sequence variation on protein expression and structure, families with isolated enamel defects were recruited. The coding exons and nearby intron sequences were amplified for each of the AI candidate genes by using genomic DNA from the proband as template. The amplification products for the proband were sequenced. Then, other family members were tested to determine their genotype with respect to each sequence variation. All subjects received an oral examination, and intraoral photographs and dental radiographs were obtained. Out of 24 families with isolated enamel defects, only six disease-causing mutations were identified in the AI candidate genes. This finding suggests that many additional genes potentially contribute to the etiology of AI.  相似文献   
47.
Matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of metalloproteinase-1 (TIMP-1) are involved in the degradation of extracellular matrix in many inflammatory diseases. Little is known regarding the expression of these mediators in dental pulp fibroblasts. The effects of proinflammatory cytokines (interleukin (IL)-1alpha and tumor necrosis factor-alpha (TNF-alpha)) and prostaglandin E2 (PGE2) on pulp fibroblast MMP-1 and TIMP-1 gene expression were investigated. Northern hybridization showed that IL-1alpha and TNF-alpha induced significant MMP-1 gene expression, with only little effect on TIMP-1 gene. Exogenous PGE2, however, upregulated TIMP-1 mRNA synthesis but not MMP-1. Concomitant addition of IL-1alpha and PGE2 or TNF-alpha and PGE2 suppressed MMP-1 mRNA production, compared with the groups treated with IL-1alpha or TNF-alpha alone. In contrast, PGE2 enhanced the upregulatory effects of TIMP-1 mRNA by IL-1alpha or TNF-alpha. Furthermore, cytokine stimulation of MMP-1 and TIMP-1 gene expressions can be enhanced or blocked by indomethacin, respectively, and reversed by exogenous PGE2. These results suggested that cytokine-stimulated MMP-1 and TIMP-1 gene expression in dental pulp fibroblasts was mediated, at least in part, by a prostaglandin-dependent pathway. The differential regulation of IL-1alpha or TNF-alpha-induced MMP-1 and TIMP-1 mRNA synthesis, as well as the direct upregulation of TIMP-1 gene expression by PGE2, also implied that prostaglandin may serve as a protective mechanism from excessive tissue breakdown during pulpitis.  相似文献   
48.
Background and Objective: Platelet‐derived growth factor‐BB is a potent mediator of tooth‐supporting periodontal tissue repair and regeneration. A limitation of the effects of topical platelet‐derived growth factor‐BB application is its short half‐life in vivo. Gene therapy has shown strong promise for the long‐term delivery of platelet‐derived growth factor in both skin ulcer healing and periodontal tissue engineering. However, little is known regarding the extended effects of platelet‐derived growth factor‐B on cell signaling via gene delivery, especially at the level of phosphorylation of intracellular kinases. This study sought to evaluate the effect of gene transfer by Ad‐PDGF‐B on human gingival fibroblasts (HGFs) and the subsequent regulation of genes and cell‐surface proteins associated with cellular signaling. Material and Methods: HGFs from human subjects were treated by adenoviral PDGF‐B, PDGF‐1308 (a dominant negative mutant of PDGF) and recombinant human platelet‐derived growth factor‐BB, and then incubated in serum‐free conditions for various time points and harvested at 1, 6, 12, 24, 48, 72 and 96 h. Exogenous PDGF‐B was measured by RT‐PCR and Western blot. Cell proliferation was evaluated by [methyl‐3H]thymidine incorporation assay. We used proteomic arrays to explore phosphorylation patterns of 23 different intracellular kinases after PDGF‐B gene transfer. The expression of α and β PDGFR and Akt were measured by Western blot analysis. Results: Sustained in vitro expression of PDGF‐B in HGFs by Ad‐PDGF‐B transduction was seen at both the mRNA and protein levels. Compared to rhPDGF‐BB and Ad‐PDGF‐1308, Ad‐PDGF‐B maintained cell growth in serum‐free conditions, with robust increases in DNA synthesis. Gene delivery of PDGF‐B also prolonged downregulation of the growth arrest specific gene (gas) PDGFαR. Of the 23 intracellular kinases that we tested in proteomic arrays, Akt revealed the most notable long‐term cell signaling effect as a result of the over‐expression of Ad‐PDGF‐B, compared with pulse recombinant human platelet‐derived growth factor BB. Prolonged Akt phosphorylation was induced by treatment with Ad‐PDGF‐B, for at least up to 96 h. Conclusion: These findings further demonstrate that gene delivery of PDGF‐B displays sustained signal transduction effects in human gingival fibroblasts that are higher than those conveyed by treatment with recombinant human platelet‐derived growth factor‐BB protein. These data on platelet‐derived growth factor gene delivery contribute to an improved understanding of these pathways that are likely to play a role in the control of clinical outcomes of periodontal regenerative therapy.  相似文献   
49.
作者曾对238例口腔鳞癌术后应用中药“参阳”方的疗效进行前瞻性的研究,本文继续对已生存4~8年的56例病员门诊随访结果进行分析.结果是生存情况:7年生存期原治疗组高于原对照组12.5%,原治疗组30例均健在,而原对照组中的26例,2例带瘤生存,1例死亡;T细胞亚群测定中,复发死亡者的CD8值均升高,CD4/CD8比值均下降;中医辨证中,正常者及肾气虚者的例数以治疗组为多,而阴虚与气阴两虚者,治疗组低于对照组;由上提示:经“参阳”方治疗者有较好的远期疗效.  相似文献   
50.
X Feng  F Chen  Z Lin  L Wang 《华西口腔医学杂志》1998,16(2):127-8, 131
It was studied the central role of nitric oxide(NO) during experimental teeth movement and the relation between nitric oxide synthetase (NOS) positive neurons and FOS like immunoreactivity (FLN) with the NADPH-diaphorase histochemistry and immunocytochemical reaction method. Results indicated that NOS positive neurons and FLN showed typical distribution in Vcx and there was some overlap between them. It suggests that NO is involved in the central modulation of the stimulating message of teeth movement, and which further explains the central modulation mechanism of experimental teeth movement in rats.  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