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   35464篇
  免费   2710篇
  国内免费   1523篇
耳鼻咽喉   327篇
儿科学   489篇
妇产科学   392篇
基础医学   5560篇
口腔科学   3020篇
临床医学   4473篇
内科学   4447篇
皮肤病学   702篇
神经病学   1499篇
特种医学   1684篇
外国民族医学   8篇
外科学   5297篇
综合类   4663篇
现状与发展   10篇
预防医学   1039篇
眼科学   528篇
药学   2254篇
  10篇
中国医学   1147篇
肿瘤学   2148篇
  2024年   101篇
  2023年   549篇
  2022年   875篇
  2021年   1164篇
  2020年   1237篇
  2019年   1168篇
  2018年   1206篇
  2017年   1143篇
  2016年   1183篇
  2015年   1253篇
  2014年   2248篇
  2013年   3147篇
  2012年   1913篇
  2011年   2234篇
  2010年   1732篇
  2009年   1754篇
  2008年   1825篇
  2007年   1859篇
  2006年   1652篇
  2005年   1532篇
  2004年   1327篇
  2003年   1146篇
  2002年   854篇
  2001年   778篇
  2000年   583篇
  1999年   549篇
  1998年   433篇
  1997年   424篇
  1996年   373篇
  1995年   333篇
  1994年   297篇
  1993年   228篇
  1992年   248篇
  1991年   233篇
  1990年   200篇
  1989年   180篇
  1988年   178篇
  1987年   158篇
  1986年   131篇
  1985年   184篇
  1984年   141篇
  1983年   106篇
  1982年   133篇
  1981年   141篇
  1980年   123篇
  1979年   87篇
  1978年   73篇
  1977年   57篇
  1976年   76篇
  1975年   30篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Fluid-fluid levels in cavernous hemangioma of soft tissue   总被引:3,自引:0,他引:3  
Five cases of cavernous hemangioma with fluid-fluid levels on magnetic resonance imaging and/or computed tomography are reported. The signal characteristics were those of blood and histological analysis of the fluid-fluid levels showed that they were blood-filled cavities in the tumor. Although this finding itself is not specific, it may help in confirming the diagnosis of cavernous hemangioma.  相似文献   
92.
基质金属蛋白酶及其抑制剂在子宫内膜癌的侵袭和转移中发挥着重要的作用。肿瘤的新生血管对肿瘤的发生、发展、转移及预后有着重要作用。微血管密度是衡量血管生成的定量指标。基质金属蛋白酶抑制剂可抑制血管的生成和MMPs对细胞外基质的降解。现将他们与子宫内膜癌的关系综述如下。  相似文献   
93.
目的介绍脱细胞异体皮肤细胞外基质医用组织补片在美容外科中的临床应用经验。方法自2002年3月至2005年10月,应用脱细胞异体皮肤细胞外基质医用组织补片,对患者不同部位进行填充的美容手术,其中头面部填充于皮下浅筋膜层,唇部、颏部、唇裂合并牙槽裂部填充于皮下深筋膜层或肌肉浅层,隆乳术中用于胸大肌减张。结果本组115例患者经1~27个月随访,1例唇裂合并牙槽裂者因补片填充量不足凹陷未完全矫正;1例鼻唇沟填充者其左侧出现血肿、局部出现硬结,于2个月后将左侧假体取出重新填充,但术后6个月仍有不平整,其余患者均获得良好的美容效果。结论脱细胞异体皮肤细胞外基质医用组织补片可以广泛地应用于美容外科的临床填充术。  相似文献   
94.
BACKGROUND: Histamine plays an important role in vascular disease. Tissue factor (TF) expression is induced in vascular inflammation and acute coronary syndromes. OBJECTIVES: This study examined the effect of histamine on tumor necrosis factor-alpha- (TNF-alpha-) vs. thrombin-induced endothelial TF expression. METHODS AND RESULTS: Histamine (10(-8)-10(-5) mol L-1), TNF-alpha (5 ng mL-1), and thrombin (1 U mL-1) induced TF expression in human endothelial cells. Although TF expression by TNF-alpha and thrombin was identical, histamine augmented TNF-alpha-induced expression 7.0-fold, but thrombin-induced expression only 2.6-fold. Similar responses occurred with TF activity. The H1-receptor antagonist mepyramine abrogated these effects. Differential augmentation by histamine was also observed at the mRNA level. Histamine-induced p38 activation preceded a weak second activation to both TNF-alpha and thrombin. Histamine-induced c-Jun NH2-terminal kinase (JNK) activation was followed by a strong second activation to TNF-alpha, and less to thrombin. Selective inhibition of this second JNK activation by SP600125 reduced TF induction to histamine plus TNF-alpha by 67%, but to histamine plus thrombin by only 32%. Histamine augmented TNF-alpha- and thrombin-induced vascular cell adhesion molecule 1 (VCAM-1) expression to a similar extent. Consistent with this observation, VCAM-1 induction to TNF-alpha and thrombin was mediated by p38, but not by JNK. CONCLUSIONS: Histamine differentially augments TNF-alpha- vs. thrombin-induced TF expression and activity, which is mediated by the H1-receptor, occurs at the mRNA level, and is related to differential JNK activation.  相似文献   
95.
OBJECTIVE: To clarify the role played by tissue factor pathway inhibitor (TFPI) in pregnancy hypertension. METHODS: Using enzyme-linked immunosorbent assays, hemostatic measurements were obtained for women with pre-eclampsia (n=51), nonproteinuric hypertension of pregnancy (n=62), postpartum pre-eclampsia 24 h after childbirth (n=31), and no hypertension (healthy pregnant controls, n=100). RESULTS: There was a significant increase in circulating free TFPI levels in women with pre-eclampsia (9.7+/-6.2 ng/mL) or nonproteinuric hypertension of pregnancy (8.3+/-5.3 ng/mL) compared with healthy controls (5.3+/-2.1 ng/mL). In women with pre-eclampsia the levels remained elevated after placental delivery (10.6+/-4.0 ng/mL). Free protein S levels were significantly higher in women with pre-eclampsia (40.0%+/-10.7%), nonproteinuric hypertension of pregnancy (37.1%+/-12.5%), or postpartum pre-eclampsia (39.3%+/-9.1%) than in healthy pregnant controls (32.2%+/-8.5%). CONCLUSION: Increased levels of the physiologically active free forms of TFPI and free protein S, 2 coagulation inhibitors, may protect women with pregnancy-induced hypertension from the risks of hemostatic activation.  相似文献   
96.
目的 分析带蒂组织瓣转移手术修复肢体软组织缺损创面的疗效。方法 选择肌瓣、岛状皮瓣、岛状肌皮瓣转移 ,直接修复缺损或转移肌瓣表面植皮覆盖。结果  2 9例慢性骨髓炎和 6例外伤后软组织缺损创面 ,肌瓣、岛状皮瓣、岛状肌皮瓣转移修复疗效满意。结论 带有营养血管的肌瓣、皮瓣肌皮瓣转移手术 ,一期修复肢体创伤、骨髓炎等所致的骨缺损腔及软组织缺损创面 ,效果好 ,因不需吻合血管 ,手术相对简单 ,临床使用安全。  相似文献   
97.
脱细胞尿道及其海绵体基质制备的实验研究   总被引:1,自引:0,他引:1  
目的 探索脱细胞尿道及其海绵体基质的制备方法。方法取健康壮年兔完整尿道及其海绵体组织,以Triton-X100与NH3H2O联合提取法进行脱细胞处理。标本做HE染色,组织学观察分析脱细胞效果。结果脱细胞处理11天后,成功获得脱细胞及其海绵体基质,所得基质外观良好。HE染色观察无细胞存在。弹力纤维排列规整,间隙较大,结构无破坏。结论利用Triton-X100与NH3H2O联合提取法可成功制备完整无细胞尿道及其海绵体基质,为尿道再造修复提供崭新思路。  相似文献   
98.
The morphologic effects of androgen deprivation in the different lobes of the rat prostate were examined by light microscopic morphometry. The prostates of Wistar male rats (260-340 g) were fixed in situ by glutaraldehyde perfusion in castrated animals 1 week after gonadectomy and in intact animals. The ventral (VP), dorsal (DP), and lateral (LP) lobes as well as the coagulating gland (CG) were dissected out, weighed, and processed for light microscopy. Using stereologic methods the following parameters were estimated for each lobe: volume fraction of connective tissue, epithelium and glandular lumina, average epithelial height, average epithelial cell volume, and total number of epithelial cells. Castration leads to a 58-76% reduction of the wet weight of all prostatic lobes. The decrease of glandular tissue is greater in VP than in LP, DP, and CG. In VP and LP, there is a 39-45% reduction of the epithelial height, and this effect is less pronounced in DP and CG. For all lobes, the shrinkage of average epithelial cell volume is in the same range (25-30%). Moreover, in VP and LP, there is a 70% reduction of the total number of cells, whereas the reduction is less in DP and CG. It thus seems that the reduction of prostatic epithelial tissue mass upon castration is due to a reduction of the number of cells as well as a reduction of the volume of individual cells. VP and LP appear to be more androgen-dependent than DP and CG.  相似文献   
99.
Apolipoprotein E is synthesized and secreted by degenerating peripheral nerve, but the role of resident endoneurial cells in this process is not clear. To exclude the involvement of nonresident cells, we examined the cellular source of endoneurial apolipoprotein E in explant cultures of rat sciatic nerve. The cellular outgrowth from these explant cultures released apolipoprotein E into the culture medium. The cellular outgrowth contained fibroblasts, Schwann cells, and a population of cells with many phenotypic characteristics of macrophages, including the production of apolipoprotein E. No other cell type in the cultures appeared to contribute to this production. These data suggest that apolipoprotein E is produced by resident endoneurial cells in explant cultures and that these cells are macrophages.  相似文献   
100.
目的研究人胎盘组织液的主要药效作用。方法建立二甲苯所致小鼠耳肿胀及大鼠棉球肉芽肿的药理模型,观察人胎盘组织液对炎症模型动物的抗炎作用。结果与模型对照组相比,连续7d肌肉注射0.1mL/kg剂量的人胎盘组织液对二甲苯所致小鼠耳肿胀起到明显抑制作用,且差异显著(P〈0.01);连续6d肌肉注射0.1mL/kg剂量的人胎盘组织液对大鼠棉球肉芽组织增生起到明显抑制作用,且差异显著(P〈0.01)。结论人胎盘组织液具有明显的抗炎作用。  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