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   57313篇
  免费   5327篇
  国内免费   4681篇
耳鼻咽喉   556篇
儿科学   546篇
妇产科学   555篇
基础医学   6573篇
口腔科学   860篇
临床医学   8311篇
内科学   8203篇
皮肤病学   462篇
神经病学   3036篇
特种医学   2260篇
外国民族医学   44篇
外科学   5454篇
综合类   10199篇
现状与发展   7篇
一般理论   5篇
预防医学   3870篇
眼科学   1426篇
药学   6296篇
  64篇
中国医学   3601篇
肿瘤学   4993篇
  2024年   184篇
  2023年   924篇
  2022年   2359篇
  2021年   2822篇
  2020年   2201篇
  2019年   1930篇
  2018年   2034篇
  2017年   1781篇
  2016年   1743篇
  2015年   2724篇
  2014年   3146篇
  2013年   2686篇
  2012年   4058篇
  2011年   4371篇
  2010年   2818篇
  2009年   2144篇
  2008年   2806篇
  2007年   2903篇
  2006年   2930篇
  2005年   2726篇
  2004年   2087篇
  2003年   2304篇
  2002年   2032篇
  2001年   1783篇
  2000年   1523篇
  1999年   1438篇
  1998年   1110篇
  1997年   1013篇
  1996年   753篇
  1995年   755篇
  1994年   647篇
  1993年   356篇
  1992年   418篇
  1991年   362篇
  1990年   292篇
  1989年   287篇
  1988年   226篇
  1987年   164篇
  1986年   142篇
  1985年   108篇
  1984年   57篇
  1983年   43篇
  1982年   34篇
  1981年   31篇
  1980年   26篇
  1979年   18篇
  1978年   6篇
  1977年   4篇
  1976年   4篇
  1958年   2篇
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
71.
PURPOSE: The APC I1307K and E1317Q variants predispose to colorectal adenomas and carcinomas in Caucasians, but data are lacking in Asians. METHODS AND RESULTS: We sequenced the APC gene from codons 1261 to 1409 and found none of 147 Chinese, 20 Malay, and 11 Indian colorectal cancer patients in Singapore to carry the APC I1307K or E1317Q variants. CONCLUSION: These variants are rare in these Asian populations, and play little role in colorectal cancer causation in Chinese.  相似文献   
72.
BACKGROUND: Blood vessel growth is necessary for normal tissue homeostatis and contributes to solid tumor growth. Methods to quantitate neovascularization should be useful in testing biological factors and drugs that regulate angiogenesis or to induce a vascular supply to promote wound healing. EXPERIMENTAL DESIGN: An extract of basement membrane proteins (Matrigel) was found to reconstitute into a gel when injected subcutaneously into C57/BL mice and to support an intense vascular response when supplemented with angiogenic factors. RESULTS: New vessels and von Willebrand factor antigen staining were apparent in the gel 2-3 days after injection, reaching a maximum after 3-5 days. Hemoglobin content of the gels was found to parallel the increase in vessels in the gel allowing ready quantitation. Angiogenesis was obtained with both acidic and basic fibroblast growth factors and was enhanced by heparin. Several substances were tested for angiostatic activity in this assay by coinjection in Matrigel with fibroblast growth factor and heparin. Platelet-derived growth factor BB, interleukin 1-beta, interleukin-6, and transforming growth factor-beta were potent inhibitors of neovascularization induced by fibroblast growth factor. Tumor necrosis factor-alpha did not alter the response but was alone a potent inducer of neovascularization when coinjected with Matrigel and heparin. Consistent with the previously demonstrated importance of collagenase in mediating endothelial cell invasion, a tissue inhibitor of metalloproteinases that also inhibits collagenases was found to be a potent inhibitor of fibroblast growth factor-induced angiogenesis. CONCLUSIONS: Our assay allows the ready quantitative assessment of angiogenic and anti-angiogenic factors and should be useful in the isolation of endothelial cells from the capillaries that penetrate into the gel.  相似文献   
73.
A novel substance, #675, found from an Streptomyces sp. SM675 culture medium, dose-dependently stimulates the proliferation of human functional liver cell 4 (FLC4). When FLC4 cells were incubated under conditions without fetal bovine serum (FBS), typical features of apoptotic cell death such as shrinkage and nuclear condensation appeared; high molecular weight (HMW) DNA fragments were found; and caspase-3 and poly (ADP-ribose) polymerase (PARP) proteins were cleaved. When FLC4 cells were incubated with #675 and without FBS, the cells grew healthy, no HMW DNA fragments were found, and caspase-3 and PARP cleavage weakened, suggesting that #675 protects FLC4 cells from apoptosis induced by FBS-deprivation. The quantitative reverse-transcribed polymerase chain reaction did not show differences in PARP or Bcl-2 mRNA expression in FLC4 cells incubated with or without #675, indicating other genes may be involved in this anti-apoptosis effect. These results show that #675 enhances FLC4 proliferation via an apoptosis-inhibition pathway, implying potential pharmacological and clinical applications.  相似文献   
74.
The expression of FcγRI, FcγRII, and FcγRIII (the IgG receptors CD64, CD32, CD16) as well as CR3 (the C3bi receptor, CD11b) on monocytes in the blood of patients with systemic lupus erythematosus (SLE) was investigated. The relationship between the receptor expression and the serum immune complex (IC) concentration was analysed. The decrease in mean fluorescence intensity (FI) of the FcγRII of patients' monocytes stained by specific monoclonal antibodies (MoAb IV3) was very close to statistical significance ( P = 0.052). The expression (FI) of CR3 (using MoAb OKM1) on monocytes of patients was also decreased, but not significantly. The detected decrease of FcγRII and CR3 was inversely correlated with the high circulating immune complex level in patients' sera. At the same time, FcγRI expression on SLE monocytes (using MoAb 32) was significantly elevated and this change was in parallel with the serum IC concentration.  相似文献   
75.
颞骨岩部的应用解剖   总被引:11,自引:0,他引:11  
在20个成人福尔马林固定的尸体头标本上,对40侧颞骨岩部的表面及内部结构进行显微解剖研究。发现表面结构与内部结构间有恒定的空间位置关系,可以通过表面标志定位内剖结构,并提出了颞骨岩部水平段颈内动脉和耳蜗定位第三角,对指导临床手术有重要价值。  相似文献   
76.
The purpose of this study was to compare estimates of body composition in two ethnic groups, 31 black and 38 white girls 10 through 16 years of age, to establish accurate and precise laboratory standards for field measures of body composition in the NHLBI Growth and Health Study HC 55025. The dual energy X-ray absorptiometry (DXA) measures of fat free mass (FFM) and % body fat (%BF) were made using Hologic QDR-1000/W. Corresponding values of FFM and %BF from underwater weighing (UWW) were determined using the two-component model of Siri, and these were corrected using the model of Lohman for white girls only. In the comparison of the different models and methods, the two-component model overestimated FFM compared to estimates from DXA for black girls, as did the corrected Lohman model for white girls. The two-component model significantly overestimated %BF in both white and black girls compared to corresponding estimates from DXA. The ratio of bone mineral content (BMC)/FFM affected the degree of %BF differences in black girls but not in white girls. Also, as the density of FFM increased or approached adult status in black girls (BMC/FFM increased), differences between the two-component model and estimates from DXA decreased. In both groups of girls, the relationship of %BF from UWW and DXA are a function of the level of body fatness. DXA values of %BF are greater than those from UWW under about 24% body fat, but the converse occurs above 25% body fat. The inability of UWW using the two-component model to account for the body composition in these girls can be corrected in part by measuring the variables for a multicomponent model or more easily by using DXA estimates of body composition. © 1994 Wiley-Liss, Inc.  相似文献   
77.
78.
目的:认识多发伤中骨折的主要特点,探讨内固定在救治中的意义。方法:回顾1994-08~1999-08间手术救治多发伤66例,对其161处骨折中的98处进行了“仿AO技术”有关方法内固定。结果:骨折均满意愈合;涉及骨折关节51个,功能恢复满意率为96.08%。结论:在多发伤中,骨折、合并伤与并发症远较“一般骨折”复杂、严重;有效固定骨折是一种重要的救命措施;内固定手术应争取在伤后24h进行,但如受条件制约,伤后1-3wk内手术也可获得满意效果;仿AO技术中的某些方法,如拉力螺钉、张力带钢丝及自动加压钢板等,用于内固定可使骨折获得卓有成效的稳定性。  相似文献   
79.
目的:探讨高血压以昼夜血压模式指导药物治疗的疗效。方法:124例高血压患者被随机分为两组:观察组80例,采用以昼夜血压模式为依据,指导选用药物进行治疗,着重加强异常升高血压部份的降压治疗,同时加强血压监测;对照组仍按照常规方法治疗,6周为1疗程,治疗前和治疗后都检测血压和24小时动态血压。结果:观察组降压的总有效率和昼夜血压模式转为正常杓形态明显高于对照组,结论:高血压病患者以昼夜血压模式为依据指导用药降压治疗有较好的医疗效果。  相似文献   
80.
Obesityisassociatedwithinsulinresis tance (IR) ,whichplaysacriticalroleinthedevelopmentoftype 2diabetesmellitus.ThemechanismofIRisrelatedtotheabnormalitiesofinsulinreceptor,pre receptor,post recep tor ,resultingindefectivemetabolicpathwayofglucose,lipidand pr…  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