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   714148篇
  免费   98947篇
  国内免费   43959篇
耳鼻咽喉   6884篇
儿科学   11906篇
妇产科学   8929篇
基础医学   87149篇
口腔科学   15779篇
临床医学   101155篇
内科学   109759篇
皮肤病学   13710篇
神经病学   44612篇
特种医学   26189篇
外国民族医学   374篇
外科学   73432篇
综合类   116586篇
现状与发展   139篇
一般理论   70篇
预防医学   48439篇
眼科学   19567篇
药学   73802篇
  680篇
中国医学   41570篇
肿瘤学   56323篇
  2024年   1578篇
  2023年   8075篇
  2022年   20466篇
  2021年   30988篇
  2020年   27288篇
  2019年   28872篇
  2018年   29670篇
  2017年   29733篇
  2016年   28714篇
  2015年   38338篇
  2014年   45345篇
  2013年   42960篇
  2012年   51215篇
  2011年   57458篇
  2010年   43881篇
  2009年   33867篇
  2008年   38800篇
  2007年   37741篇
  2006年   36853篇
  2005年   35163篇
  2004年   23669篇
  2003年   22468篇
  2002年   19238篇
  2001年   16810篇
  2000年   16834篇
  1999年   16750篇
  1998年   10085篇
  1997年   9922篇
  1996年   7814篇
  1995年   7276篇
  1994年   6003篇
  1993年   3959篇
  1992年   4995篇
  1991年   4348篇
  1990年   3733篇
  1989年   3268篇
  1988年   2705篇
  1987年   2279篇
  1986年   1931篇
  1985年   1537篇
  1984年   879篇
  1983年   628篇
  1982年   373篇
  1981年   383篇
  1980年   304篇
  1979年   368篇
  1978年   159篇
  1977年   148篇
  1974年   152篇
  1973年   119篇
排序方式: 共有10000条查询结果,搜索用时 343 毫秒
991.
腹腔镜肝右后叶囊肿开窗引流术35例报告   总被引:6,自引:1,他引:5  
目的:探讨肝右后叶肝囊肿的腹腔镜处理方法。方法:1998年1月~2005年12月对35例有症状的肝右后叶囊肿(21例主要位于Ⅵ段,14例主要位于第Ⅶ段)采用四孔法行囊肿开窗引流术。囊肿位于肝右后叶上段者采用肝上入路,胆囊牵引钳或三叶钳推压肝脏使其向前向下,暴露肝后囊肿,囊肿开窗,修剪带蒂大网膜放入囊肿。囊肿位于肝右后叶下段者采用肝下入路,超声刀切开肝结肠韧带,右三角韧带及肝肾间疏松组织,胆囊牵引钳抬起肝脏,囊肿开窗,大网膜放入囊腔引流。结果:35例肝右后叶肝囊肿均在腹腔镜下完成肝囊肿开窗引流术,无中转开腹手术。15例采用肝上入路,20例采用肝下入路。手术时间30~95min,平均46min。无手术并发症。35例病理检查结果均为先天性肝囊肿。术后症状均消失。术后住院2~5d,平均3.8d。35例随访6~36个月,平均34个月,33例无复发,2例(为肝上入路病例)囊肿未完全消失,但较术前明显缩小,无明显症状,观察半年未见增大。结论:肝下及肝上入路囊肿开窗引流是腹腔镜下处理肝右叶肝囊肿的有效方法。  相似文献   
992.
目的 比较微波子宫内膜去除术(MEA)和子宫切除术(AH)治疗异常子宫出血的疗效.方法 将异常子宫出血80例分为MEA组和AH组各40例,比较两组临床疗效、手术时间、术中出血及手术前后白细胞变化. 结果 MEA和AH治疗异常子宫出血的有效率无显著差异(39/40 vs 40/40,χ2=0.000,P=1.000).MEA手术时间短[(4.8±1.2)min vs(102.5±34.6)min,t=17.848,P=0.000];术中出血少[0 ml vs(138.3±40.6)ml,t=21.544,P=0.000]. 结论 MEA是一种治疗异常子宫出血有效且微创的手术.  相似文献   
993.
腔内激光治疗大隐静脉曲张192例报告   总被引:4,自引:1,他引:3  
目的 探讨腔内激光治疗大隐静脉曲张的疗效。方法 2004年7月~2006年3月我院对192例238条肢体大隐静脉曲张行高位结扎、激光烧灼静脉主干和小腿曲张静脉。小腿局部严重曲张的静脉团,另做切口做局部切除或点状抽拨。结果 本组一次治愈率96.2%(229/238)。9例9条肢体术后因仍有少量曲张静脉存在,局麻下行切除或再次激光治愈。114例大隐静脉主干及小腿局部条索状硬结、疼痛;9例皮肤灼伤。术后住院时间4~8 d,平均5.6 d。158例随访1~18个月,平均11.6月,未见复发。结论 腔内激光治疗大隐静脉曲张效果确切,创伤小。  相似文献   
994.
目的观察卡维地洛对不稳定型心绞痛(UAP)患者高敏C反应蛋白(hs-CRP)、白介素-6(IL-6)及细胞间可溶性黏附分子1(sICAM-1)水平的影响。方法UAP患者62例采用完全随机化方法分成对照组(n=30)和治疗组(n=32),在常规抗血小板、扩血管治疗基础上,对照组予美托洛尔(12.5mg,2次/d×3d)口服,治疗组服卡维地洛(6.25mg,2次/d×3d),在治疗前后分别测定hs-CRP、IL-6、sICAM-1值。结果对照组和治疗组在治疗前hs-CRP、IL-6、sICAM-1均无显著性差异;用药后两组3指标均较用药前显著降低(P<0.05);治疗组在用药后IL-6、sI-CAM-1显著低于对照组(P<0.05)。同时,用药后两组患者的心率、血压、心肌耗氧量均较用药前显著降低(P<0.05),治疗组的心肌耗氧量显著低于对照组(P<0.05)。结论卡维地洛可显著降低UAP患者的炎症因子IL-6、sICMA-1水平。  相似文献   
995.
OBJECTIVE: To examine health care seeking pathways for patients with tuberculosis (TB) and barriers related to these pathways in counties under the National TB Control Programme in rural China. METHODS: A cross-sectional study was conducted in two counties of east China in 2004-2005. A total of 557 TB patients were recruited and interviewed by physicians at the time of TB diagnosis. RESULTS: Of 557 participants, 13.3% had presented to a specialised county TB dispensary (CTD) directly after onset of symptoms, 31.4% had first sought care at a village health station and 51.2% had visited a township or county hospital first. The proportion of referral by a first health care provider to a CTD was highest in county level hospitals (73.5%) and lowest in village health stations (21.7%). The most prompt pathway from first health care seeking to TB diagnosis was to visit a CTD directly, with a median provider's delay of only one day. There was an increase in provider's delay when more health facilities were involved. CONCLUSION: To improve direct referral from general health care providers, especially village health care workers, to TB specialists would significantly shorten the delays in TB diagnosis in rural China.  相似文献   
996.
997.
表皮生长因子对大鼠脑梗死后神经功能恢复的影响   总被引:2,自引:0,他引:2  
目的 观察表皮生长因子(EGF)对大鼠脑梗死后神经功能恢复的影响。方法 采用肾血管性高血压大鼠制作一侧大脑中动脉皮层支闭塞(MCAO)模型。MCAO术后24 h,32只大鼠侧脑室注入10μl EGF(100μg/L),连续2d,共2μg(EGF组);32只大鼠只注入不含EGF的等量溶液(对照组)。MCAO术后1、2、3和4w,行Bederson神经功能评分后,免疫印迹检测双侧大脑半球生长相关蛋白(GAP43)、突触囊泡蛋白(SYN)和胶质原纤维酸性蛋白(GFAP)的表达。结果 与同期对照组相比,EGF组大鼠在MCAO术后1、2w神经运动功能恢复更好,脑梗死灶同侧半球GAP43、SYN和GFAP有更早期和更高表达(P<0.05)。结论 GAP43、SYN和GFAP等蛋白的早期高峰表达可能与EGF引起的早期神经可塑性改善有关。  相似文献   
998.
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   
999.
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   
1000.
Bradyarrhythmia requiring permanent pacing after heart transplantation remains a common problem. Sinus node dysfunction is the most common indication, and late onset of atrioventricular (AV) block has rarely been reported. We report the case of a patient who developed advanced AV block at 41 months after transplantation. Right bundle branch block with progressive increase of QRS complex duration was noted in serial electrocardiograms. At the time of late AV block development, the patient did not have acute rejection and coronary angiogram was normal. The mechanism of late onset of AV block is unclear, but it may be caused by progressive conduction.  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