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   15837篇
  免费   1100篇
  国内免费   345篇
耳鼻咽喉   225篇
儿科学   325篇
妇产科学   50篇
基础医学   805篇
口腔科学   699篇
临床医学   1895篇
内科学   6935篇
皮肤病学   13篇
神经病学   182篇
特种医学   386篇
外科学   3126篇
综合类   1701篇
现状与发展   1篇
预防医学   256篇
眼科学   208篇
药学   417篇
  4篇
中国医学   37篇
肿瘤学   17篇
  2024年   25篇
  2023年   401篇
  2022年   651篇
  2021年   1017篇
  2020年   954篇
  2019年   968篇
  2018年   867篇
  2017年   479篇
  2016年   442篇
  2015年   564篇
  2014年   1032篇
  2013年   937篇
  2012年   615篇
  2011年   766篇
  2010年   596篇
  2009年   621篇
  2008年   568篇
  2007年   547篇
  2006年   589篇
  2005年   500篇
  2004年   407篇
  2003年   414篇
  2002年   350篇
  2001年   331篇
  2000年   292篇
  1999年   292篇
  1998年   233篇
  1997年   216篇
  1996年   195篇
  1995年   180篇
  1994年   165篇
  1993年   139篇
  1992年   127篇
  1991年   101篇
  1990年   85篇
  1989年   73篇
  1988年   60篇
  1987年   72篇
  1986年   55篇
  1985年   70篇
  1984年   72篇
  1983年   38篇
  1982年   43篇
  1981年   27篇
  1980年   28篇
  1979年   19篇
  1978年   17篇
  1977年   5篇
  1976年   14篇
  1973年   8篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
Is There an Advantage to Repairing Infected Mitral Valves?   总被引:5,自引:0,他引:5  
Background. The therapy for native mitral valve endocarditis is in evolution. Antibiotics have significantly improved survival rates, but patients with complications of endocarditis may require surgical treatment.

Methods. Between January 1985 and December 1995, 146 patients underwent surgical therapy (repair or replacement) for native mitral valve endocarditis. All patients had documented bacterial endocarditis. Univariate and multivariate analyses were performed to determine predictors of hospital death, long-term event-free survival, and probability of repair. Patients were evaluated in three groups: all patients, patients with acute endocarditis, and patients with chronic endocarditis.

Results. There were ten hospital deaths (6.8%). Patients undergoing repair had a lower hospital mortality rate (p = 0.008) then those having replacement. Event-free survival was improved after mitral valve repair in the overall group (p = 0.02) and in the group with healed (chronic) endocarditis (p = 0.05). Although the acute endocarditis group demonstrated an improved event-free survival rate after mitral valve repair versus replacement (74% versus 20% at 6 years), this did not reach statistical significance.

Conclusions. We conclude that mitral valve repair is preferable to mitral valve replacement when possible, in patients with complications of endocarditis, as repair results in a lower hospital mortality and an improved long-term survival.  相似文献   

72.
A case of active prosthetic valve infective endocarditis (PVE) due toCandida glabrata was successfully treated by the systemic administration of fluconazole. A 66-year-old Japanese man with infective endocarditis of unknown etiology underwent aortic and mitral valve replacement to treat severe aortic and mitral regurgitation associated with multiple organ failure. Postsurgical cultures of arterial blood were repeatedly positive forC. glabrata, and therefore fluconazole was administered either intravenously or orally at a dose of 400 mg/day for 46 days. During that time the signs of inflammation including fever such as an elevated white blood cell count and the presence of C-reactive protein (CRP) all improved while the blood cultures became negative. Fluconazole is thus considered to be effective in treating PVE caused byC. glabrata. When administering this treatment, it is also important to monitor the patient's renal and liver function.  相似文献   
73.
人工心脏瓣膜感染性心内膜炎临床分析   总被引:1,自引:0,他引:1  
目的 探讨人工心脏瓣膜感染性心内膜炎 (PVE)的临床特征 ,提高PVE的诊治水平。方法 通过分析 2 6例PVE的临床表现 ,分析其治疗和预后情况。结果 PVE临床不少见 ,发热是最常见的临床表现 ( 92 .3 % ) ,其次是贫血 ( 88.5% ) ,栓塞 ( 2 6.9% )。血培养和超声心动图是诊断PVE的重要手段 ,阳性率分别为 46.2 %和 73 .1%。早期PVE较晚期PVE预后差、死亡率高 ,分别为 66.7%、3 3 .3 %。主张早期、大剂量、长疗程的抗生素治疗 ,早期手术治疗可改善预后。本组病人总死亡率 3 4 .7% ,死亡原因 :心力衰竭 ( 77.8% )、栓塞 ( 2 2 .2 % )。结论 PVE预后差、死亡率高 ,应早期预防、早期诊断、早期治疗  相似文献   
74.
We describe a new respiratory valve system with minimal dead space, which allows measurement of ventilation and oxygen uptake during swimming. The device offers considerable advantages in efficiency and accuracy over current equipment, and can be used in conjunction either with a miniaturized telemetry system for oxygen uptake measurement or with a conventional system. The valve has a low airflow resistance, a small dead space (15 ml), and an electrically operating, closed-circuit pump to remove excess water from the expiratory tube. The external form and the buoyancy of the valve have been hydrostatically and hydrodynamically designed to reduce drag and to ensure a correct mass in the water. To obtain this result a very sophisticated material, carbon fibre, has been utilized. Our studies showed that this respiratory system is ideal for obtaining valid and reliable values of oxygen uptake during swimming, even at high speed and in endurance swimming tests.  相似文献   
75.
风湿性二尖瓣狭窄心肌病理改变与心肌运动的关系   总被引:3,自引:0,他引:3  
胡晓旻  李彤  蔡振杰  周更须  张海滨 《医学争鸣》2004,25(12):1130-1133
目的 :探讨风湿性二尖瓣狭窄 (Mitralstenosis ,MS)患者心肌病理改变与心肌运动的关系 .方法 :MS患者 2 2例术前行常规心脏超声及组织多普勒成像 (Dopplertissueimag ing,DTI)检查 ,于心尖四腔切面记录室间隔侧二尖瓣环长轴方向射血期频谱S波和舒张期频谱D波峰值及心电图R波至频谱S波起始点的时间T ,选取 3个波幅最大的心动周期 ,算出此 3个心动周期的平均值S3 、D3 和T3 ;二尖瓣置换术中切取左室乳头肌行病理检查 .结果 :微动脉Di/Do与D3 呈正相关 ,(r =0 .5 0 ,P <0 .0 5 ) ;心肌纤维化程度与T3 呈正相关 ,(r=0 .6 8,P <0 .0 5 ) ;而S3 与D3 呈正相关 ,(r =0 .4 3,P <0 .0 5 ) .结论 :术前DTI检查测量D3 及T3 ,可以反映心肌病理变化 ,有助于对MS患者手术适应证的掌握及对预后的判断  相似文献   
76.
双频谱指数在心脏瓣膜置换术中的观察   总被引:2,自引:0,他引:2  
目的应用脑电双频谱指数(BIS)监测常规经验麻醉下瓣膜置换术病人的麻醉深度(意识水平),观察BIS在伤害性刺激时的变化.方法选择30例瓣膜置换术病人,采用芬太尼、咪唑安定、哌库溴铵及心血管活性药物对病人实施麻醉;术中监测并有专人分别记录入室(基础值)、诱导后、插管后、切皮后、锯胸骨时、缝胸骨时及术毕BIS和MAP,HR各参数值,观察不同阶段各参数的变化.结果诱导后各参数均明显降低,虽然切皮后、锯胸骨及缝胸骨等强刺激后MAP和HR未见统计学意义的显著改变,但BIS却显著增高(P<0.01);全部病人锯胸骨时BIS均在60(67.28±8.97)以上,缝胸骨时63(68.46±8.70)以上,而无1例低于50者.结论该组瓣膜置换术病人麻醉偏浅,尤以锯胸骨、缝胸骨及术毕等时段为甚,表现为BIS值偏高,有知晓发生;知晓可发生在临床认为满意的麻醉中;应用BIS监测,可更加合理地评价麻醉深度.  相似文献   
77.
陈伟  许晓华  李泉水  李沿江  王卫东  廖涛  孙雁 《医学争鸣》2003,24(13):1240-1242
目的:应用彩色多普勒超声心动图指导经皮二尖瓣球囊成形术(PBMV)治疗风湿性二尖瓣狭窄的价值、方法:运用彩超对行PBMV的患进行术前术后检查,观察二尖瓣钙化程度及部位、开口形状、瓣口面积、二尖瓣返流(MR)程度、瓣下病变、左房左室大小、左房有无血栓.结果:91例PBMV术后患中,术后MR72例,其中MR新出现19例,MR加重8例、与术前对比,术后二尖瓣开放幅度、二尖瓣口面积、二尖瓣跨瓣压、二尖瓣压差半降时间较术前有明显改善趋势,左房内径、肺动脉内径较术前有缩小趋势.同时,术后左房压、右室压及肺动脉压也有下降趋势。结论:彩超能明确PBMV治疗二尖瓣狭窄的效果。影响:PBMV效果的因素较多,但二尖瓣钙化的程度、部位和瓣膜形态较为重要。  相似文献   
78.
Transesophageal echocardiography was conducted to determine the systolic pattern of the anterior mitral leaflet in patients with flat chest, and to differentiate it from that associated with mitral valve prolapse. The fronto-sagittal index (an index of chest flattening) was determined in 50 subjects using chest radiographs, and was used to classify them into a flat chest group (index < 0.38, n = 28) and a normal chest group (index ≥ 0.38, n = 22). We then used transesophageal echocardiography to examine the anterior leaflet in these subjects. A significant positive correlation was observed between the fronto-sagittal index and the short-to long-axis diameter ratio of the left ventricle in all patients. These parameters, and the left atrial dimension were lower in the flat than the normal chest group. The clear zone area of the anterior leaflet during mid-to late-systole was significantly larger in the flat chest group. However, no intergroup differences existed in the rough zone area of the anterior leaflet or in the middle scallop area of the posterior leaflet. Mitral regurgitation was observed in 20 and 12 subjects in the flat and normal chest groups, respectively. The maximum mitral regurgitant area did not differ between the two groups. The clear zone area of the anterior leaflet increased significantly following inhalation of amyl nitrite in 22 subjects of both groups, but the other areas did not increase. The mitral regurgitant area decreased or disappeared after amyl nitrite at a similar rate in each group. Thus, the decrease in the antero-posterior dimension of the thorax in subjects with flat chest affects the systolic pattern of the clear zone of the anterior leaflet more than that of the rough zone of the anterior leaflet or the posterior leaflet. This systolic pattern in such patients differs from that associated with mitral valve prolapse.  相似文献   
79.
Optimal initial palliation and a subsequent staged approach is mandatory for high-risk Fontan candidates. We describe the case of mitral atresia with severe tricuspid regurgitation and pulmonary hypertension successfully managed by repeated palliation from the neonatal period and 2-stage Fontan surgery. A 1-month-old boy diagnosed with mitral atresia and double-outlet right ventricle underwent pulmonary artery banding at 1 month of age, followed by repeated pulmonary artery banding accompanied by tricuspid annuloplasty and atrial septal defect enlargement at 6 months. Because of the presence of pulmonary artery distortion, right ventricular dysfunction, and borderline pulmonary vascular resistance, a hemi-Fontan procedure was conducted with extended pulmonary artery plasty when the boy was 3 years and 8 months old. Cardiac catheterization done 3 months after showed improvement in risk factors, and the final Fontan operation (total cavopulmonary connection) was successfully done in conjunction with repeated tricuspid annuloplasty when the boy was 4 years and 5 months old. The patient remains in excellent clinical condition at the last follow-up 5 years after the final Fontan procedure with sinus rhythm and good ventricular function.  相似文献   
80.
Disorders of conduction occurring simultaneously in both normal and accessory pathways of patients with Wolff-Parkinson-White (WPW) syndrome have only rarely been observed. To our knowledge this is the first report of impaired conduction in both pathways in WPW syndrome due to mitral annulus calcification (MAC). This case of WPW syndrome type A presented the following conduction abnormalities: (1) right bundle-branch block; (2) transient second-degree AV block with prolonged PR interval of the conducted beats; (3) during electrophysiological study, induction of tachycardia, dependent (phase 3) second-degree AV block, and occasionally conduction of two consecutive beats, the second showing an increased H-V interval (from 25 to 60 ms) and left bundle-branch block (LBBB) pattern, due to (4) infrahisian conduction abnormality.  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