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   44734篇
  免费   2408篇
  国内免费   1275篇
耳鼻咽喉   15篇
儿科学   160篇
妇产科学   44篇
基础医学   1711篇
口腔科学   45篇
临床医学   7223篇
内科学   13745篇
皮肤病学   67篇
神经病学   3938篇
特种医学   1586篇
外科学   1059篇
综合类   10023篇
预防医学   1579篇
眼科学   46篇
药学   4916篇
  66篇
中国医学   2146篇
肿瘤学   48篇
  2024年   80篇
  2023年   456篇
  2022年   1008篇
  2021年   1459篇
  2020年   1402篇
  2019年   1070篇
  2018年   1077篇
  2017年   1171篇
  2016年   1357篇
  2015年   1337篇
  2014年   3181篇
  2013年   2847篇
  2012年   2908篇
  2011年   3089篇
  2010年   2553篇
  2009年   2385篇
  2008年   2418篇
  2007年   2432篇
  2006年   2409篇
  2005年   2022篇
  2004年   1569篇
  2003年   1363篇
  2002年   1217篇
  2001年   1135篇
  2000年   993篇
  1999年   835篇
  1998年   655篇
  1997年   621篇
  1996年   456篇
  1995年   373篇
  1994年   355篇
  1993年   308篇
  1992年   249篇
  1991年   226篇
  1990年   192篇
  1989年   159篇
  1988年   159篇
  1987年   156篇
  1986年   125篇
  1985年   144篇
  1984年   115篇
  1983年   76篇
  1982年   69篇
  1981年   54篇
  1980年   41篇
  1979年   32篇
  1978年   35篇
  1977年   14篇
  1976年   11篇
  1973年   5篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
The purpose of this study was to investigate whether, to whatextent, and through which mechanisms intravenous heparin, administeredbefore and after streptokinase, affects the plasma levels ofD-dimer and fibrinogen in myocardial infarction. Data concerningmortality and incidence of coronary recanalization in patientsreceiving heparin and thrombolytic therapy after acute myocardialinfarction are controversial; furthermore, the mechanisms throughwhich heparin acts in combination with thrombolytic therapyare unclear. Thirty-eight patients with acute myocardial infarctiontreated with streptokinase were considered. Nineteen of themreceived, immediately before the beginning of thrombolytic treatment,a bolus of heparin (100 U. kg1 intravenously) and, 2 h later,intravenous heparin in doses raising the partial thromboplastintime to 2-2.5 times the normal value (Group 1); the remaining19 did not receive anticoagulant treatment (Group 2). Multipledeterminations of plasma D-dimer and fibrinogen levels wereobtained in all patients before, and in the seven days followingthrombolytic treatment. Six hours after streptokinase, fibrinogendecreased from 304 ± 34 to 61 ± 34 mg. dt1 inGroup 1 and from 312 ± 29 to 38 ±21 mg. dt1 inGroup 2 (P<002 versus Group 1). The same difference betweengroups persisted at the 12th and at the 18th hour. D-dimer values,from 0-5 ± 01 \ig. dl1 in Group 1 and 04 ±01 fig.dt1 in Group 2, increased at the 1st hour to 37.2 ± 36.5fig. dt1 and 52.2 ± 39.8 µg. dl1, respectively.A peak value was reached in both groups at the 6th hour, whichwas followed by a slow decrease. A significant difference betweenthe two groups (P<0.05) was observed at the 1st, 2nd, 4thand 6th hour. An inverse correlation between maximal changesof fibrinogen and of D-dimer was found in both groups (r= 0.89,P<0.001 in Group 1; r=-0.81, P<0.001 in Group 2). The relationship between D-dimer and fibrinogen variations afterstreptokinase and changes induced by heparin, support the hypothesisthat the decrease of fibrinogen, following thrombolysis, isnot only the consequence of its direct degradation, but alsothe result of its transformation by streptokinase into fibrin,fibrin cross-linked (with facilitation of thrombogenic condition)and then into the stable catabolite, D-dimer. These data confirma thrombogenic effect of streptokinase therapy; this tendencycan be limited by prompt use of high doses of heparin.  相似文献   
72.
Beta-adrenergic blockade has been a mainstay in the treatment of patients with acute myocardial infarction for nearly two decades. Clearly, it has withstood the test of time. The emergence of thrombolytic therapy, however, has shifted the medical community's focus, raising questions as to the benefit of beta-adrenergic blockade. Although further investigation is warranted, the available evidence suggests that beta blockers can be given safely to selected patients following coronary thrombolysis, particularly in the absence of moderate to severe left ventricular dysfunction.  相似文献   
73.
Quality of life was assessed 4–6 months after an acutemyocardial infarction in a randomized double-blind study ofenalapril versus placebo. Quality of life was evaluated usingthe Nottingham Health Profile (NHP), the Physical Symptoms DistressIndex (PSDI), the Work Performance Scale (WPS) and the LifeSatisfaction Index (LSI). The study comprised 36 women (aged46–85 years, mean 68) and 96 males (aged 39–81 years,mean 62). Quality of life did not differ significantly between patientstreated with enalapril versus placebo. The scores were (enalaprilvs placebo, mean± SE): average NHP 15.4 ± 2.3vs 17.1 ± 2.3; PSDI 9.5± 1.0 vs 10.8 ±0.9; WPS 19.8 ± 2.0 vs 19.4 ± 1.4; LSI 24.1 ±1.0 vs 22.5 ±1.4. Men reported a better quality of lifethan women on most assessments, and non-smokers and ex-smokersbetter than smokers. Patients with moderate or severe anginapectoris had a worse quality of life measured by PSDI and NHPthan patients with minimal or no angina pectoris. Patients withcongestive heart failure had a higher PSDI than those without(13.6 ± 1.7 vs 9.4 ± 0.7, P<0.05), while nosignificant differences were observed in the NHP scores. In conclusion, quality of life was similar in enalapril andplacebo- treated patients after an acute myocardial infarction.However, it was reduced in patients with angina pectoris orheart failure and in those who continued smoking.  相似文献   
74.
目的 床旁临时起搏器作为急性心肌梗死(AMI)的常备急救设备的价值及其在基层医院推广应用的可行性研究。方法 回顾性研究分析2001-2003年间不能床旁植入临时起搏器与2004-2005年能床旁植入临床起搏器抢救AMI的住院病死率、心衰、心源性休克、2mo后再次住院发生率。临时起搏器植入术安全性的指标比较。结果 不能床旁植入临时起搏器组的住院病死率为14.58%,心衰发生率为27.08%,心源性休克发生率为12.5%,2mo后再次住院发生率为16.67%。床旁植入临时起搏器组的住院病死率为3.57%,心衰发生率为7.14%,心源性休克发生率为3.57%,2mo后再次住院发生率为3.57%,两组相比p〈0.01有显著性差异。而起搏器植入的安全性指标:起搏器植入成功率为100%,脱位率为10.7%,并发症发生率为14.3%,住院病死率3.57%。结论 床旁临时起搏器抢救AMI住院病死率低,心衰发生率、心源性休克发生率及2mo后再次住院发生率低,应作为AMI抢救的常备急救设备,另外床旁临时起搏器植入是安全的、有效的,成功率高,操作不难,在基层医院(二甲医院)可推广应用。  相似文献   
75.
细胞移植治疗心肌梗死的研究与展望   总被引:2,自引:0,他引:2  
杜文  卢绍禹 《医学综述》2006,12(14):856-857
细胞移植是治疗心肌梗死的一种新策略,本文对目前应用于临床研究的骨骼肌卫星细胞移植及骨髓干细胞移植治疗心肌梗死的进展进行综述。上述两种细胞移植均具有来源丰富、无排斥反应的特点,而且通过研究观察表明,上述两种细胞移植后,心脏功能均能得到改善,故具有美好发展前景。但二者亦均具有不足之处和需要解决的问题,还需进一步研究与探索。  相似文献   
76.
Probably the most under-utilised application of echocardiography is in patients with coronary artery disease (CAD). This under-utilisation is striking since echocardiography can be very valuable in evaluating the natural history and therapy of CAD. One reason why echocardiography is not being utilised to its fullest is because of the reliance on videotape to record and display echocardiograms. This medium is time consuming and inconvenient for clinicians to review studies, it is not ideal for detecting subtle wall motion abnormalities, and videotape is impractical for comparing serial studies. Recording and storing echocardiograms on a digital medium overcomes these difficulties. Digital cine loops of single cardiac cycles provide great versatility. Multiple views or studies can be displayed simultaneously, subtle changes in wall motion are more easily detected and different views, or serial studies, can be readily compared. Such images can be displayed on computers on the ward or in the coronary care unit (CCU) and be available 24 hours a day, seven days a week at the convenience of the clinician. One does not need to find a recording on a two hour videotape, which may be in the ultrasound instrument, and one can view the exam in 30 sec instead of 5 to 10 min. Regional and global left ventricular function is one of the most important manifestations of CAD. With new therapeutic efforts at restoring myocardial function and limiting infant expansion, assessing LV function is more important than ever. Digital echocardiography is an extremely practical and convenient way for clinicians to obtain this information.  相似文献   
77.
For investigating the effect of acupuncture on ischemic arrhythmia and its mech-anism, adult albino rats with ligated anterior descending branch of coronary artery as experimentalmodel were treated with or without acupuncture, and others with imitative operation but without bothcoronary artery ligation and acupuncture treatment were used as control. It was found in acupuncturegroup that the fibrillation-liability of ischemic myocardium was efficiently decreased, the affinity ofAch-M receptors on membranes of ischemic myocardium was markedly increased, and the tolerance ofischemic myocardium to atropine was elevated in the experiment of atropine inducing fibrillation.These results indicate that acupuncture may play a therapeutic role on ischemic arrhythmia throughactivating the activity of muscarine-like receptors of cholinergic nervous system.  相似文献   
78.
TIA对后继脑梗死神经保护作用的临床研究   总被引:7,自引:0,他引:7  
目的探讨预先短暂性脑缺血发作(TIA)是否对后继脑梗死具有神经保护作用。方法根据脑梗死患者是否预先发生同侧的TIA分为TIA组和无TIA组,分别从TIA持续时间、发作次数、与脑梗死间隔时间及梗死部位几方面同无TIA组比较,采用ADL评分标准,评定患者预后恢复情况。结果Ⅰ级预后预先有TIA的占72%,无TIA的占63%,二者相比差异无显著性(X~2=3.31,P>0.05)。但脑梗死前有TIA且持续时间在5~20min、发作次数2~3次,与脑梗死间隔不超过1周者,其Ⅰ级预后较多,同无TIA组相比较差异有显著性(P<0.05)。结论脑梗死前发生的TIA有可能对人脑产生缺血耐受作用。TIA的神经保护性与其发作持续时间、发作次数及与脑梗死间隔时间有一定关系。  相似文献   
79.
影像学分型与急性脑梗死患者认知功能关系的研究   总被引:1,自引:1,他引:0  
目的探讨影像学分型与急性脑梗死患者认知功能关系。方法对136例急性大脑梗死患者于发病后24~72h内行颅脑MRI检查确定梗死部位、测量病灶大小并作出影像学分型,于发病1周内,在患者床前采用简易精神状态检查法(mini—mentalstate examination,MMSE),检测患者的认知功能,并同步进行事件相关电位P300的检测,判断患者认知功能的情况,对比分析应用MRI进行的影像学分型与认知功能关系。结果额叶、颞叶脑梗死患者的MMSE和WAIS—RC评分明显低于顶枕叶和基底节区梗死患者,P300潜伏时明显长于顶枕叶和基底节区梗死的患者,但其P300波幅低于顶枕叶和基底节区梗死的惠者;中梗死和多发性梗死患者的MMSE和WAIS—RC评分明显低于顶枕叶和基底节区梗死患者,B300潜伏时明显长于顶枕叶和基底节区梗死的患者,但其P300波幅低于顶枕叶和基底节区梗死的患者。结论影像学分型与急性脑梗死患者认知功能有相关性。  相似文献   
80.
不同剂量普伐他汀治疗急性脑梗死的疗效和安全性研究   总被引:1,自引:0,他引:1  
目的:探讨不同剂量普伐他汀在脑梗死急性期治疗的可行性、降脂疗效及安全性。方法:脑梗死急性期病人146例,随机分为3组,A组(50例)为对照组,B组(49例)每晚服普伐他汀10mg,C组(47例)每晚服普伐他汀20mg,观察30d。比较治疗前后血脂、神经功能缺损评分、生化指标等变化,并记录服药后不良反应。结果:各组总胆固醇(TC)、低密度脂蛋白(LDL-C)、超敏C-反应蛋白(hs-CRP)在治疗后都有所下降,C组下降最显著,B组次之,A组下降程度较小。A组TG治疗前后无明显变化,B组和C组TG治疗后有所下降,两组间无明显差别。脂蛋白(Lpa)在A组治疗后有下降,B组无明显变化,C组较前轻度升高。各组治疗前后神经功能缺损评分均有降低,但各组之间比较无明显差异(P〉0.05)。观察期间所有病人均能耐受普伐他汀,治疗前后肝、肾功能、肌酸激酶(CK)等无明显变化。结论:在脑梗死急性期应用普伐他汀(每日10~20mg)是安全可行的,且每日20mgTC、TG降低更显著,脑梗死急性期的病人应用普伐他汀后取得较好的降脂疗效,神经功能缺损评分的改善有待较长期观察。  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