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   263315篇
  免费   24465篇
  国内免费   20581篇
耳鼻咽喉   2011篇
儿科学   2301篇
妇产科学   3005篇
基础医学   32556篇
口腔科学   4270篇
临床医学   37860篇
内科学   38476篇
皮肤病学   2393篇
神经病学   14873篇
特种医学   9532篇
外国民族医学   198篇
外科学   25079篇
综合类   44059篇
现状与发展   74篇
一般理论   27篇
预防医学   15850篇
眼科学   8168篇
药学   28186篇
  299篇
中国医学   15566篇
肿瘤学   23578篇
  2024年   932篇
  2023年   4373篇
  2022年   11346篇
  2021年   14030篇
  2020年   10639篇
  2019年   9229篇
  2018年   9666篇
  2017年   8510篇
  2016年   8094篇
  2015年   12173篇
  2014年   14954篇
  2013年   12522篇
  2012年   18720篇
  2011年   21529篇
  2010年   13028篇
  2009年   10058篇
  2008年   13331篇
  2007年   13361篇
  2006年   13593篇
  2005年   13848篇
  2004年   8201篇
  2003年   7606篇
  2002年   6375篇
  2001年   5695篇
  2000年   6424篇
  1999年   7178篇
  1998年   4735篇
  1997年   4753篇
  1996年   3675篇
  1995年   3511篇
  1994年   2898篇
  1993年   1965篇
  1992年   2213篇
  1991年   1842篇
  1990年   1565篇
  1989年   1333篇
  1988年   1133篇
  1987年   990篇
  1986年   748篇
  1985年   608篇
  1984年   348篇
  1983年   214篇
  1982年   115篇
  1981年   126篇
  1980年   82篇
  1979年   90篇
  1965年   1篇
  1962年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
142.
BACKGROUND: As a non-invasive technique which can provide comprehensive biological information, 1H-magnetic resonance spectroscopy (1H-MRS) may provide valuable reference data for irreversible recovery or reversible changes in ischemic tissue after stroke. OBJECTIVE: To monitor and evaluate the effect of the urokinase thrombolytic therapy after experimental acute cerebral ischemia by 1H-MRS technology and investigate its adaptability. DESIGN: Randomly controlled animal study. SETTINGS: Shenzhen Hospital of Peking University and National Key Laboratory of Pattern and Atom & Molecular Physics, Wuhan Physics and Mathematics Institute, Chinese Academy of Science. MATERIALS: Eleven healthy adult Sprague-Dawley (SD) rats, weighing 260–300 g and of both genders, were supplied by Experimental Animal Center of Tongji Medical Collage, Huazhong University of Science and Technology [SCXK (e) 2004-007]. 4.7T superconducting nuclear magnetic resonance meter was provided by Brucker Company. METHODS: The experiment was carried out in Shenzhen Hospital of Peking University and National Key Laboratory of Pattern and Atom & Molecular Physics, Wuhan Physics and Mathematics Institute, Chinese Academy of Science from August 2003 to December 2005. ① The rats were randomly divided into 30-minute self-thrombo-embolism group (n =6) and 60-minute self-thrombo-embolism group (n =5). Six rats in 30-minute self-thrombo-embolism group were occluded with clot embolus for 30 minutes and 5 rats in 60-minute self-thrombo-embolism group were occluded for 60 minutes. 10 000 U/kg urokinase was dissolved in 2 mL saline and the operation lasted for 5 minutes. ② 1H-MRS was performed before thrombolysis and at 3 hours and 24 hours after successful embolization. The metabolic changes of N-acetyl-L-aspartic acid (NAA)/phosphocreatine (PCr) + creatine (Cr), choline phosphate (Cho)/PCr+Cr and lactic acid (Lac)/PCr+Cr in the region of interests were analyzed. ③ The T2W image was conducted 24 hours after the thrombolytic therapy with TR=500 ms and TE=25 ms. ④ The subjects were sacrificed immediately after 1H-MRS and the brain tissues were cut into pieces and stained with HE method; in addition, pathological changes were observed under optic microscope. MAIN OUTCOME MEASURES: ① Metabolic changes of NAA/PCr+Cr, Cho/PCr+Cr and Lac/PCr+Cr in the region of interests; ② T2W image at 24 hours after the thrombolysis; ③ pathological observation of brain tissue. RESULTS: Eleven rats were all involved in the final analysis. ① Metabolic changes in the region of interests : In 30-minute self-thrombo-embolism group, the Lac peak emerged immediately after the embolism, but the ischemic zone decreased 3 hours after the thrombolytic therapy (0.252±0.01, 0.603±0.01, P < 0.01). Lac/(PCr+Cr) ratio was 0.290±0.01 at 24 hours after thrombolysis, which was higher than that at 3 hours after thrombolysis (P < 0.01). The NAA/ (PCr+Cr) ratio decreased significantly at 3 hours after the thrombolysis as compared with that before thrombolysis (0.922±0.16, 1.196±0.01, P < 0.05). In 60-minute self-thrombo-embolism group, the Lac/(PCr+Cr) ratio was higher at 3 hours after thrombolysis than that before thrombolysis (0.846±0.12, 0.601±0.11, P < 0.05) and the NAA/(PCr+Cr) decreased at 3 hours after the embolism. Fluctuation of NAA/ (PCr+Cr) ranged from 0.68 to 0.75 before thrombolysis and from 0.71 to 0.75 at 3 hours after thrombolysis. ② T2W image: T2W image showed that 2 subjects in 30-minute self-thrombo-embolism group whose Lac/NAA was higher than 0.7 suffered from intracranial hemorrhage. This meant that the subjects with Lac/NAA > 0.7 were more likely to suffer from intracranial hemorrhage. ③ Histological and morphological examinations: Optic microscope demonstrated that interspace surrounding nerve cells was widened at ischemic center; neurons were swelling; nucleus was stained lightly; pyknosis and mesenchymal edema were mainly observed in lateral cortex of brow and vertex and in lateral part of corpus striatum. CONCLUSION: ①Compound parameters in ischemic area before thrombolysis should be regarded as an important predicting marker for thrombolytic therapy, effect evaluation and termination. ② 1H-MRS combining with other imaging technique is a detecting way for screening cases who are suitable for thrombolytic therapy.  相似文献   
143.
X Dong  M He  X Song  B Lu  Y Yang  S Zhang  N Zhao  L Zhou  Y Li  X Zhu  R Hu 《Diabetic medicine》2007,24(12):1482-1486
AIMS: Our aim was to assess performances of the Cockcroft-Gault and simplified Modification of Diet in Renal Disease (MDRD) formulae in estimating glomerular filtration rate (GFR) in Chinese diabetic populations and their association with vascular risks. METHODS: A total of 1009 patients with Type 2 diabetes were categorized into low estimated GFR groups (GFR < 60 ml/min/1.73 m(2)) and control groups by the two equations. The performances of these formulae were assessed at different stages of kidney function. Carotid artery intima-media thickness (IMT) and the prevalence of diabetic retinopathy or albuminuria were compared among the groups. The ability of these formulae to identify established vascular risk markers using sensitivity, specificity, positive and negative predictive values were also compared. RESULTS: The prevalence of low estimated GFR was 32.7% with the Cockcroft-Gault formula and 5.2% with the MDRD formula, respectively. In low estimated GFR subjects by the MDRD formula, IMT was significantly thicker than those by the Cockcroft-Gault formula (1.2 mm vs. 1.0 mm; P < 0.05), with a higher prevalence of albuminuria (78.4 vs. 52.8%, P < 0.05) and diabetic retinopathy (46.5 vs. 30.5%; P < 0.05). The Cockcroft-Gault formula gave a specificity of 71.7% and a sensitivity of 37.0%, and the MDRD formula gave a specificity of 96.6% and a sensitivity of 7.9% in estimating low GFR relevant for established vascular risks. CONCLUSIONS: These formulae performed differently in Chinese diabetic populations. The simplified MDRD formula is minimally superior to the Cockcroft-Gault formula for its high specificity and positive predictive values in estimating low GFR relevant for vascular risks.  相似文献   
144.
创伤性浮膝伴血管损伤的早期诊治   总被引:3,自引:0,他引:3  
目的 探讨创伤性浮膝同时伴同侧血管损伤患者的早期诊断及救治.方法 总结1996年6月~2002年12月收治28例30个浮膝的手术固定方法、血管修复情况及术后治疗和恢复情况.结果 术后伤口一期愈合5例,17例伤口二期行植皮修复,4例胫前骨折部外露二期行皮瓣转移术,截肢2例,保肢成功率92.9%.术后26例经18个月~8年随访,骨折均愈合,下肢功能恢复优良率64.3%.结论 对浮膝损伤患者应高度重视伴有血管损伤可能,早期作出诊断,积极合理治疗,对患者预后至关重要.  相似文献   
145.
“黄风湿”系列疗法——火针封闭治疗痛风石的疗效观察   总被引:1,自引:0,他引:1  
痛风是一种由嘌呤代谢紊乱所致的疾病,日久不愈、反复发作则逐渐形成痛风石沉积。常规治疗对痛风石效果不明显。黄再军医院采用火针封闭疗法治疗痛风石36例,经临床观察治愈率为69.4%,显效率为25.0%,有效率为5.6%,总有效率达100%。  相似文献   
146.
目的:建立乳腺非典型增生病动物模型,探讨非典型增生与血管生成的关系。方法:采用灌服二甲基苯蒽+颈部枷具方法复制大鼠肝郁血瘀型乳腺非典型增生动物模型,并给予中药乳复汤治疗。常规染色观察大鼠乳腺组织病理组织形态.免疫组化方法检测MVD、VEGF和bFGF的表达。结果:病证模型组乳腺非典型增生率90%.较单纯造模组高.P=0.0415;中药乳复汤治疗组非典型增生率较病证模型组低.P=0.0459;随着一般增生到非典型增生程度加重,MVD计数增多,VEGF、bFGF的表达升高,P〈0.05。结论:病证结合造模更适合中医动物实验要求,中药乳复汤具有抑制血管生成作用。  相似文献   
147.
张占香  杨树青 《护理研究》2005,19(18):1650-1651
医院感染是指病人在入院时不存在,也不处于潜伏期,而是在医院内发生的感染,也包括在医院里获得治疗,出院后发病的病人感染[1].癌症病人是一个特殊的群体,是医院感染的易感和高危人群,由于疾病本身引起消瘦无力、营养不良、甚至恶病质,免疫力低下、再加上接受放射线治疗后引起骨髓功能抑制、消化道功能障碍、皮肤反应及其他副反应等危险因素,医院感染发生率高,因此放疗科的医院感染控制是非常重要的工作.本文通过对我院放疗科病房2003年8月-2004年4月住院病人137例中发生医院感染病例12例进行分析,总结出一些控制医院感染的方法,现将其介绍如下.……  相似文献   
148.
目的探讨继发性外部性脑积水的CT特征及随访观察的价值.方法回顾性分析了36例有明确病因的继发性外部性脑积水的CT特征及随访结果.结果双侧额或额顶部蛛网膜下腔对称性增宽者36例(100%),双侧裂池增宽者36例(100%),额顶部脑沟增宽加深者31例(86.11%),前纵裂池增宽者36例(100%),脑基底池扩大者21例(58.33%),脑室轻度扩大者7例(19.44%).复查10例患儿其中8例外部性脑积水及临床症状消失,智力良好.其余2例均伴外伤史,其中一例复查出现脑萎缩征象,另一例出现脑积水征象.结论C检查及随访观察对于继发性外部性脑积水的诊断、鉴别诊断及指导临床治疗具有重要的价值.  相似文献   
149.
Molecular determinants of cetuximab efficacy.   总被引:17,自引:0,他引:17  
PURPOSE: To investigate whether mRNA expression levels of cyclin D1 (CCND1), cyclooxygenase 2 (Cox-2), epidermal growth factor receptor (EGFR), interleukin 8 (IL-8), and vascular endothelial growth factor (VEGF), all members of the EGFR signaling pathway, are associated with clinical outcome in patients with EGFR-expressing metastatic colorectal cancer (CRC) treated with cetuximab. PATIENTS AND METHODS: Thirty-nine patients with metastatic CRC, refractory to both irinotecan and oxaliplatin, were enrolled on IMCL-0144 and treated with single-agent cetuximab. The intratumoral mRNA levels of CCND1, Cox-2, EGFR, IL-8, and VEGF were assessed from paraffin-embedded tissue samples using laser-capture microdissection and quantitative real-time polymerase chain reaction. RESULTS: There were 21 women and 18 men with a median age of 64 years (range, 35 to 83 years). Higher gene expression levels of VEGF were associated with resistance to cetuximab (P = .038; Kruskal-Wallis test). The combination of low gene expression levels of Cox-2, EGFR, and IL-8 was significantly associated with overall survival (13.5 v 2.3 months; P = .028; log-rank test). Both findings were independent of skin toxicity that was itself significantly correlated to survival. Patients with a lower mRNA amount of EGFR had a longer overall survival compared with patients that had a higher mRNA amount (7.3 v 2.2 months; P = .09; log-rank test). Patients with lower expression of Cox-2 had a significantly higher rate of grade 2 to 3 skin reactions under cetuximab treatment. CONCLUSION: This pilot study suggests that gene expression levels of Cox-2, EGFR, IL-8, and VEGF in patients with metastatic CRC may be useful markers of clinical outcome in single-agent cetuximab treatment.  相似文献   
150.
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