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   30276篇
  免费   2333篇
  国内免费   730篇
耳鼻咽喉   32篇
儿科学   664篇
妇产科学   782篇
基础医学   1918篇
口腔科学   34篇
临床医学   5317篇
内科学   9851篇
皮肤病学   59篇
神经病学   486篇
特种医学   1615篇
外国民族医学   4篇
外科学   4349篇
综合类   3973篇
现状与发展   1篇
一般理论   1篇
预防医学   787篇
眼科学   181篇
药学   2152篇
  24篇
中国医学   665篇
肿瘤学   444篇
  2024年   44篇
  2023年   583篇
  2022年   838篇
  2021年   1355篇
  2020年   1440篇
  2019年   1354篇
  2018年   1298篇
  2017年   1035篇
  2016年   958篇
  2015年   1098篇
  2014年   1969篇
  2013年   2283篇
  2012年   1481篇
  2011年   1622篇
  2010年   1283篇
  2009年   1340篇
  2008年   1293篇
  2007年   1281篇
  2006年   1191篇
  2005年   1108篇
  2004年   891篇
  2003年   776篇
  2002年   640篇
  2001年   641篇
  2000年   444篇
  1999年   526篇
  1998年   446篇
  1997年   448篇
  1996年   358篇
  1995年   356篇
  1994年   346篇
  1993年   279篇
  1992年   282篇
  1991年   261篇
  1990年   211篇
  1989年   157篇
  1988年   159篇
  1987年   167篇
  1986年   138篇
  1985年   174篇
  1984年   159篇
  1983年   119篇
  1982年   83篇
  1981年   103篇
  1980年   77篇
  1979年   53篇
  1978年   47篇
  1977年   47篇
  1976年   38篇
  1975年   19篇
排序方式: 共有10000条查询结果,搜索用时 406 毫秒
71.
72.
Autotransfusion of mediastinal shed blood after open heart surgery has become a common and accepted procedure in reducing the need for homologous transfusion during the last 15 years. The objectives of the present study were to investigate the oxygen delivery capacity of autotransfused shed mediastinal blood, compared to patient-blood, during cardiopulmonary bypass and in the postoperative period.
Ten consecutive patients undergoing elective cardiac surgery were studied. Mediastinal shed blood was collected in the cardiotomy reservoir and retransfused during the first 18 postoperative hours. The oxygen delivery capacity of the blood to the tissues was calculated by use of the oxygen status algorithm (OSA 2.0) programme and measurement of the 2,3-diphosphoglycerate (2,3-DPG) concentration.
Autotransfusion volume ranged from 450–1530 ml per patient (median 824 ml). Shed blood had a mean haemoglobin level of 8.8 g/dl and 7.4 g/dl at 1 h and 6 h of autotransfusion, respectively. There were no significant changes of 2,3-DPG concentration in the patient-blood during cardiopulmonary bypass or after autotransfusion compared to preoperative values. P50 for oxygen (3.6 and 3.6 kPa) and 2,3-DPG concentrations (5.3 and 5.1 mikromol/ml erythrocyte) in shed mediastinal blood (1h and 6h postoperatively) were not significantly different compared to patient-blood.
The results demonstrate that the oxygen delivery capacity of shed mediastinal blood is maintained and that the oxygen affinity of patient-blood is not influenced by autotransfusion.  相似文献   
73.
Three dimensional (3D) phase contrast angiograms contain velocity data, which is discarded after the reconstruction of the projections. In extension to earlier work on velocity quantification with ungated 2D phase data, this paper shows that a useful estimate of the average velocity and flow rate can be extracted from ungated 3D phase contrast angiograms. Simulations and experiments in a phantom and in vivo were performed. For pulsatile flow and strong spin saturation, an over-estimation of the flow rate at the net in-flow end of the imaging volume and underestimation at the net out-flow end was observed. Imaging at lower RF tip angles yielded flow rates close to the correct value within the entire imaging volume. In contrast to ungated 2D experiments, the flow rates determined by repeated 3D experiments showed no variation.  相似文献   
74.
Study of the dynamics of cardiac output in rats with different tolerance to acute massive blood loss showed that the pumping ability of the heart remains intact during the entire posthemorrhagic period in all high-resistant and in 65% low-resistant rats. In 35% rats that were low-resistant to blood loss, the cardiac output deficiency syndrome developed after cessation of bleeding against the background fall in arterial pressure and a decrease in the hepatic blood flow, which are the signs of rapid variant of the dysfunction produced by acute blood loss. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 126, No. 10, pp. 384–388, October, 1998  相似文献   
75.
脉络膜挫伤   总被引:2,自引:2,他引:0  
回顾64例外伤性脉络膜挫伤。多发于20-30岁的青年男性;最常见有拳击伤;临床主要表现为视力下降,眼底可见脉络膜出血灶及裂伤口,荧光眼底血和造影可帮助诊断。脉络膜挫伤多发生于黄斑部,其次为视乳头周围,多为单个,1-PD大小,脉络膜破裂的形态多为长弧形,脉络膜出血多为圆形;脉络膜破裂与出血常同时出现。  相似文献   
76.
S.M Hay  J Barré  S.N Bell 《The Knee》1998,5(4):301-303
A fit 38-year-old female patient developed absent foot pulses following a routine arthroscopic partial medial meniscectomy. Irrigation fluid, which was delivered using an arthroscopic flushing set, had extravasated through a ruptured Baker's cyst into the popliteal fossa causing vascular compression and spasm. The pulses gradually returned to normal following the procedure. Knee arthroscopy is a common procedure and a Baker's cyst is a common sequel to degenerative disease. With the increasing popularity of pressurised fluid irrigation systems, this previously unreported complication is both relevant and important.  相似文献   
77.
埋藏式自动复律除颤器(AICD)能降低恶性快速室性心律失常患者的猝死发生率,已经得到基本肯定,但其猝死率的降低,在相当程度上取决于能否对置入AICD患者进行认真随访,不断完善其治疗。本文报告1例随访16个月经验,并就随访结果,结合文献,略予讨论。  相似文献   
78.
应用99mTc-甲氧基异丁基异腈(MIBI)对29例受检者进行首次通过法心室显像,测定左室射血分数(LVEF),并与同期平衡法心室显像测得的LVEF进行相关分析。结果:首次通过法和平衡法心室显像测得的LVEF分别为(46.5±16.7)%、(49.1±16.1)%(P>0.05)。相关分析结果显示,二者有明显的相关(r=0.787,P<0.01)。结果表明:99mTc-MIBI为心肌显像剂,采用首次通过法心室显像,在观察心肌血流改变的同时,可准确可靠地评价左室收缩功能状态。  相似文献   
79.
对61例心包疾病的CT表现进行了分析。少量心包积液主要聚集在前、左象限,中、大量积液则主要向左或左后象限扩展。根据积液厚度及分布象限可作积液量的评估。缩窄性心包炎CT均显壁层心包增厚,以心包腹侧面增厚为主,部分病人伴有心包钙化、房室扩大及腔静脉扩张。心包肿瘤侵犯或转移表现为心包不规则增厚或呈结节状改变。  相似文献   
80.
Summary Background Pregnancy is prossible in female patients who underwent cardiac transplantation but is associated with unpredictable risks. Methods A 23-year old female patient underwent cardiac transplantation because of dilatative cardiomyopathy. Results Against our advice, she became pregnant 4 months after transplantation. Following an uneventful pregnancy, spontaneous vaginal delivery occurred 13 months after transplantation. The patient gave birth to a healthy new-born in good physical condition. Thereafter, the patient refused to attend any further routine follow-up control. 9 months after delivery, the patient was admitted to hospital in severe cardiac shock. Biopsy showed a serious, acute rejection which was treated with a course of methylprednisolone. Clinically, the patient recovered within 1 week, but died from acute myocardial infarction 1 day after discharge from hospital. Conclusions Only women without a history of rejection episodes, with good kidney function, good graft function, and high compliance should be counselled to become pregnant.   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