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   29927篇
  免费   1307篇
  国内免费   882篇
耳鼻咽喉   246篇
儿科学   509篇
妇产科学   124篇
基础医学   1390篇
口腔科学   195篇
临床医学   4345篇
内科学   10232篇
皮肤病学   44篇
神经病学   244篇
特种医学   2132篇
外科学   2235篇
综合类   5564篇
预防医学   1325篇
眼科学   133篇
药学   2309篇
  34篇
中国医学   947篇
肿瘤学   108篇
  2024年   21篇
  2023年   237篇
  2022年   647篇
  2021年   945篇
  2020年   803篇
  2019年   590篇
  2018年   688篇
  2017年   665篇
  2016年   734篇
  2015年   926篇
  2014年   2293篇
  2013年   2037篇
  2012年   2021篇
  2011年   2114篇
  2010年   1740篇
  2009年   1835篇
  2008年   1892篇
  2007年   1844篇
  2006年   1723篇
  2005年   1396篇
  2004年   1161篇
  2003年   944篇
  2002年   751篇
  2001年   652篇
  2000年   533篇
  1999年   401篇
  1998年   335篇
  1997年   308篇
  1996年   222篇
  1995年   216篇
  1994年   195篇
  1993年   136篇
  1992年   117篇
  1991年   138篇
  1990年   93篇
  1989年   90篇
  1988年   74篇
  1987年   85篇
  1986年   57篇
  1985年   67篇
  1984年   65篇
  1983年   40篇
  1982年   55篇
  1981年   37篇
  1980年   32篇
  1979年   29篇
  1978年   25篇
  1977年   30篇
  1975年   15篇
  1973年   12篇
排序方式: 共有10000条查询结果,搜索用时 875 毫秒
91.
目的总结冠心病患者行冠状动脉旁路移植术(CABG)和激光心肌血运重建术(TMLR)中的治疗难点、围术期处理要点,以提高冠心病患者的外科治疗效果。方法1997年5月~2006年1月,1405例冠心病患者中在体外循环下行CABG825例,其中单纯CABG666例,CABG+心瓣膜手术98例,CABG+室壁瘤手术55例,CABG+左心房粘液瘤摘除术2例,CABG+室间隔穿孔修补术2例,CABG+升主动脉成形术1例,CABG+纵隔内肿瘤切除术1例;非体外循环下CABG(OPCAB)500例;单纯TMLR30例,CABG+TMLR50例。结果每例移植旁路血管2.9±1.0支。住院死亡42例(3.0%),死亡原因包括出血、心肌梗死、低心排血量综合征、肾功能衰竭、多器官功能衰竭等。术后发生并发症70例,包括出血、低心排血量综合征、心肌梗死、肾功能不全等,均经积极的对症处理后治愈或好转。术前心绞痛(CCS)为~级的1177例患者中,术后1154例(98.0%)改善为0~级。术后随访857例(62.9%),随访时间8.3±2.9个月。随访6个月时788例(91.9%)无心绞痛发作,复查超声心动图提示:左心室射血分数0.66±0.10,较术前提高7.9%,生活质量较术前大为提高。结论CABG已成为治疗冠心病最有效的常规手术,只要能正确掌握适应证,有效地加强围术期管理,便可以扩大手术适应证范围,降低手术死亡率和并发症发生率,提高手术疗效。  相似文献   
92.
64层螺旋CT三联检查在急性胸痛诊断中的应用   总被引:13,自引:0,他引:13  
目的探讨64层螺旋CT(MSCT)三联检查显示急性胸痛患者肺动脉、胸主动脉和冠状动脉病变的能力及其临床应用价值。方法70例患者进行64层MSCT回顾性心电门控肺动脉、胸主动脉和冠状动脉联合检查。采用多平面重组(MPR)、最大密度投影(MIP)、曲面重组(CPR)及容积再现(VR)多种重组技术显示肺动脉、胸主动脉和冠状动脉,评价成像质量能否满足临床诊断需要。结果平均扫描时间(8.5±1.0)s,总对比剂用量100ml。肺动脉和主动脉增强后CT值均≥200HU者占95.7%(67/70);冠状动脉显影图像质量优的节段占85.8%(720/839),图像质量良的节段占8.6%(72/839),图像质量差的节段占5.6%(47/839)。共检出冠状动脉狭窄≥50%者20例,肺动脉栓塞2例,主动脉夹层2例。结论64层MSCT三联检查能够在8s左右1次扫描完成肺动脉、胸主动脉和冠状动脉检查,图像质量可以满足临床诊断需要,在急性胸痛病因诊断中具有很高的临床应用价值。  相似文献   
93.
目的:研究血管紧张素转换酶(ACE)基因与中国人群冠心病(CHD)、高血压病(EH)及2型糖尿病(T2DM)的关系。方法:250例呈不同组合的EH、T2DM以及CHD患者及90例正常对照用改良的聚合酶链反应(PCR)方法检测ACE基因型,比较基因型及等位基因频率分布。结果:①无合并CHD的T2DM及EH组ACE基因型及等位基因频率与正常对照无显著差异;②CHD组无论是否合并EH及/或T2DM,Ⅲ基因型及Ⅰ等位基因频率均显著低于正常对照,而DD基因型及D等位基因频率均显著高于正常对照;③T2DM合并CHD组及EH合并CHD组中Ⅱ基因型及Ⅰ等位基因频率均显著低于正常对照,而DD基因型及D等位基因频率均显著高于正常对照。结论:ACE基因多态性与中国人群CHD相关。这种关联亦见于EH或T2DM合并CHD中,但ACE基因仅是CHD发病的遗传学基础,而与是否合并EH及/或T2DM无关。  相似文献   
94.
目的:探讨高龄患者胃十二指肠穿孔围手术期处理的具体措施。方法:对22例75岁以上高龄患者胃十二指肠穿孔手术资料进行回顾性分析。结果:全组治愈20例,死亡2例。结论:只要准确估计病情,充分细致做好术前准备,选择合适的术式及最佳麻醉,术中、术后严密监测,提高操作技术,尽量缩短手术时间,加强术后护理及各种有效的治疗,高龄患者是可以安全度过围手术期的。  相似文献   
95.
目的:评价常规心电图检查中ST-T改变在冠心病诊断中的价值。方法:以选择性冠状动脉造影为对照,研究连续194例病人临床症状及心电图ST-T改变与造影结果的关系。结果:造影发现136例病人有明显的冠状动脉狭窄性病变,58例未发现明显病变。非典型心脏症状的病人无论是否有ST-T的异常,冠状动脉造影的阳性率仅4%~14%,而典型症状伴有ST-T异常的病人阳性率较高(89.4%)。结论:ST-T异常伴有典型心脏症状的诊断冠状动脉病变的可靠指标。  相似文献   
96.
We report on the development of features of the postpericardiotomy syndrome following coronary perforation during balloon angioplasty, in a patient that was managed conservatively. The case illustrates that while cardiac tamponade does not invariably follow coronary perforation, late consequences derived from this complication may occur. It also widens the spectrum of conditions where the postpericardiotomy syndrome has been observed.  相似文献   
97.
The aim of this study was to determine the diagnostic accuracy of technetium-99m tetrofosmin myocardial imaging for the localization of coronary artery stenoses of different degrees of severity. Stress-rest single-photon emission tomography (SPET) was performed on separate days in 80 patients (64 males, 16 females; mean age 61 years; 43 patients with previous myocardial infarction; 18 patients with pharmacological stress), within 6 months of coronary angiography. Scintigraphic images were blindly and independently evaluated by three observers. Coronary stenosis was defined as a >50% narrowing in luminal diameter; severe stenosis was defined as a proximal stenosis of >75% or a peripheral stenosis of >90%. Coronary angiography revealed normal coronary arteries or insignificant coronary stenosis in 13 patients and significant coronary stenoses in 67 patients. The sensitivity and specificity of 99mTc-tetrofosmin SPET in respect of severely stenosed vessels were, respectively, 80% and 65% for the left anterior descending artery (LAD), 100% and 46% for the right coronary artery (RCA) and 58 and 78% for the left circumflex artery (LCx) territories. Considering all the significantly stenosed vessels, a significant decrease in sensitivity was observed for LAD territories (to 59%, P=0.05), and a nonsignificant decrease for RCA (88%) and LCx (47%) territories while specificity values remained essentially unchanged. No significant changes in sensitivity or specificity were observed when regions with previous myocardial infarction were excluded. In conclusion, the sensitivity of 99mTc-tetrofosmin SPET for the localization of individual stenosed vessels is only moderate when all significant stenoses are considered, but the ability of this technique to predict the location of severe coronary artery stenoses seems satisfactory, with the exception of the low specificity in respect of RCA territories. Received 26 April and in revised form 7 June 1997  相似文献   
98.
Stress echocardiography has been considered an accurate method for the diagnosis of coronary artery disease in hypertensive patients and in patients with left ventricular hypertrophy. In contrast, the specificity of myocardial perfusion scintigraphy in these patients has been questioned. The aim of this study was to compare the accuracy of these two imaging modalities in conjunction with dobutamine stress test for the diagnosis of coronary artery disease in hypertensive patients with and without left ventricular hypertrophy. Dobutamine (up to 40 μg kg–1min–1) stress echocardiography in conjunction with sestamibi (MIBI) single-photon emission tomography (SPET) was performed in 84 patients with the diagnosis of systemic hypertension who had been referred for evaluation of myocardial ischaemia. Ischaemia was defined as new or worsened wall motion abnormalities at echocardiography and reversible perfusion defects at SPET. Significant coronary artery disease (≥50% luminal diameter stenosis) was detected in 66 patients (79%). The sensitivity, specificity and accuracy of the ischaemic pattern at echocardiography for the diagnosis of coronary artery disease were 73% (CI 63%–82%), 83% (CI 75%–91%) and 75% (CI 66%–84%), those for MIBI were 67% (CI 57%–77%), 83% (CI 75%–91%) and 70% (CI 60%–80%) respectively (P = NS vs echocardiography). Significant stenosis was detected in 123 (49%) of the 252 analysed coronary arteries. The sensitivity, specificity and accuracy of echocardiography for the regional diagnosis of coronary artery disease were 63% (CI 56%–69%), 90% (CI 86%–94%) and 77% (CI 72%–82%). Those for MIBI were 58% (CI 51%–64%), 91% (CI 87%–94%) and 75% (CI 69%–80) respectively (P = NS vs echocardiography). Left ventricular hypertrophy was detected in 59 patients (70%) by echocardiography and did not influence the overall or regional specificity of echocardiography or MIBI SPET. It is concluded that in hypertensive patients, dobutamine stress echocardiography and MIBI SPET have a comparable accuracy for the overall and regional diagnosis of coronary artery disease. Hypertensive patients with or without left ventricular hypertrophy should not be considered unsuitable candidates for stress myocardial perfusion scintigraphy. Received 10 July and in revised form 19 September 1997  相似文献   
99.
We retrospectively reviewed the records of 250 consecutive patients undergoing coronary artery bypass graft surgery (CABG) from January 1994 through January 1996 to determine the incidence of persistent postoperative neurological dysfunction after CABG and to compare normothermic and moderate hypothermic cardiopulmonary bypass (CPB). Normothermic CPB was used in 128 patients (36°–37°C) and hypothermic CPB (27°–28°C) in 122 patients. Postoperative neurological dysfunction included focal motor deficits, delayed recovery of consciousness (>24h) after surgery, and seizures within 1 week postoperatively. Persistent neurological dysfunction was diagnosed if complete resolution had not occurred within 10 days of surgery. The incidence of persistent postoperative neurological dysfunction was 4.1% in the hypothermic CPB group and 2.3% in the normothermic CPB group. There were no statistically significant differences between the two groups (P=NS). These results suggest that normothermic CPB did not increase the incidence of persistent postoperative neurological dysfunction compared to hypothermic CPB.  相似文献   
100.
Stress thallium-201 tomography was performed to compare the flow capacities of arterial and saphenous vein grafts in patients with coronary artery bypass grafting (CABG). One hundred and seven consecutive patients (95 male and 12 female; mean age 58±9.1 years) underwent exercise-redistribution 201Tl myocardial single-photon emission tomography 4–5 weeks after CABG. When a reversible perfusion defect was present in the area covered by a patent bypass graft, the flow capacity of the graft was defined as insufficient. Of all 285 grafts, 211 were considered as complete bypass. Reversible perfusion defects were present in 29 (27%) of 108 myocardial areas supplied by patent arterial grafts but in only 5 (5%) of 103 myocardial areas supplied by patent saphenous vein grafts (P<0.0001). In the LAD area reversible defects were observed in 22 of 82 areas covered by arterial grafts, in contrast to only 1 of 29 areas covered by venous grafts (P<0.01); in the RCA area reversible defects were observed in 7 of 17 and 4 of 41 areas respectively (P<0.01). There was no difference between the native coronary artery stenosis bypassed by patent arterial and venous grafts (88%±12% vs 86%±14% respectively, P=0.27). In conclusion, flow capacities during peak myocardial demand were more frequently insufficient in arterial bypass grafts than in saphenous vein grafts. Received 23 May and in revised form 7 August 1997  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