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   240816篇
  免费   18095篇
  国内免费   6613篇
耳鼻咽喉   3083篇
儿科学   3906篇
妇产科学   4915篇
基础医学   34136篇
口腔科学   4738篇
临床医学   25998篇
内科学   42616篇
皮肤病学   5466篇
神经病学   16474篇
特种医学   11138篇
外国民族医学   53篇
外科学   30264篇
综合类   12923篇
现状与发展   26篇
一般理论   100篇
预防医学   14805篇
眼科学   7290篇
药学   21837篇
  67篇
中国医学   5699篇
肿瘤学   19990篇
  2024年   357篇
  2023年   2210篇
  2022年   5930篇
  2021年   8873篇
  2020年   5492篇
  2019年   6416篇
  2018年   7444篇
  2017年   5754篇
  2016年   6782篇
  2015年   9369篇
  2014年   11511篇
  2013年   12389篇
  2012年   18637篇
  2011年   18702篇
  2010年   11205篇
  2009年   9097篇
  2008年   13384篇
  2007年   13084篇
  2006年   12483篇
  2005年   11936篇
  2004年   9795篇
  2003年   8622篇
  2002年   7376篇
  2001年   6140篇
  2000年   5775篇
  1999年   5296篇
  1998年   2592篇
  1997年   2250篇
  1996年   1904篇
  1995年   1755篇
  1994年   1511篇
  1993年   1118篇
  1992年   2162篇
  1991年   2062篇
  1990年   1823篇
  1989年   1645篇
  1988年   1522篇
  1987年   1331篇
  1986年   1257篇
  1985年   1095篇
  1984年   774篇
  1983年   646篇
  1982年   440篇
  1981年   427篇
  1980年   363篇
  1979年   582篇
  1978年   428篇
  1977年   399篇
  1976年   356篇
  1974年   384篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
分析白内障摘除并后房型人工晶体植入术中发生晶体后囊破裂的原因和讨论处理方法。分析55例(55眼)白内障摘除并后房型人工晶体植入术中发生晶体后囊破裂的原因,裂口形态,大小及部位。根据具体情况采用不同处理方法。该术中合并症好发于抽吸晶体皮质及植入人工晶体时,各21例(38.2%),后囊破裂大小约3mm的39例(70.9%),5mm的13例(23.6%)。大于6mm的3例(5.5%)。后囊破裂的部位及形  相似文献   
992.
Objectives: The purpose of this study was to determine if a device placed externally around the aortic root decreases regurgitant flow in acute aortic regurgitation. Background: Aortic regurgitant flow is dependent on central aortic pressure and the aortic root and leaflet geometry. It may be possible to decrease aortic regurgitant severity by reducing aortic root size or dimension changes. Methods: Aortic regurgitation was created in eight calf heart specimens suspended in a continuous flow system. Retrograde and antegrade aortic flow and distending aortic pressure were measured at baseline and after placement of an external aortic device at the level of the aortic annulus. In two additional specimens, the incompetent aortic valve was visualized fiberoptically before and after placement of the external device. Acute aortic regurgitation was created surgically in four live calves by excising a portion of the aortic leaflets. Antegrade and retrograde flow, left ventricular pressure, and central aortic pressure were measured at baseline, after creation of aortic regurgitation, and after placement of the external device. Results: In the in vitro calf specimens, regurgitant flow decreased from 46.9 cc/sec to 15.1 cc/sec (66.0%± 21.8% decrease) after placement of the external device (p < 0.001). The regurgitant orifice area decreased from 0.13 ± 0.04 cm2 to 0.04 ± 0.02 cm2 after device placement (p < 0.001). Antegrade flow was reduced to a smaller extent (20.0%± 19.2% decrease) by the device (p < 0.05). Placement of the device around the aorta resulted in improved coaptation of the leaflets with a marked reduction in defect size by endoscopic visualization. Use of the external aortic device was associated with improvement in aortic regurgitant severity in three of four calves with surgically created aortic regurgitation. Concluslons: In these preliminary studies, acute experimental aortic regurgitant severity is decreased by the use of an external aortic device, probably due to reduction in aortic annular dimension changes and improved aortic leaflet apposition. Further studies are needed to determine the effectiveness of this device in chronic aortic regurgitation. (J Card Surg 1994;9:304–313)  相似文献   
993.
复方丹参注射液与维生素B6、C注射液配伍稳定性试验   总被引:12,自引:1,他引:11  
本文观察了复方丹参注射液与维生素B6、维生素C注射液的配伍稳定性,结果表明复方丹参注射液与维生素B6注射液可以在4h内配伍使用,而不能与维生素C配伍。  相似文献   
994.
We evaluated the AMPLICOR cytomegalovirus (CMV) PCR kit for the diagnosis of neurologic CMV infections on 43 positive and 112 negative archived cerebrospinal fluid specimens originally tested by an in-house PCR method. The AMPLICOR kit showed sensitivity and specificity of 95 and 100%, respectively, versus the home-grown assay, indicating its utility in this clinical setting.  相似文献   
995.
口内进路高颧骨整形术   总被引:4,自引:0,他引:4  
高颧骨整形术中为达到理想的美容效果,必须将颧部整形与面部其他器官的美容作一个整体来考虑,文中介绍了矫正高颧骨畸形的一种新的手术方法,手术进路有两种,一种是口内,另一种是冠状切口,自1994上12月至1996年2月,通过口内进路设计一种V形切口,用骨切削技术矫正高颧骨畸形,共施术于25例病人,手术简单,安全,可对门诊病例采用局部麻醉施行手术,本组病人大多数经6月至1年以上随方,术后显示疗效满意,暂时  相似文献   
996.
Intestinal schistosomiasis japonica: CT-pathologic correlation   总被引:1,自引:0,他引:1  
  相似文献   
997.
A tissue equivalent phantom was used in the study and absored x-ray doses.It measuring for some important organs of head and neck by four routive sialography methods (panoramic conventional x-ray radioagraphy,tomography,fluoroscope,CT) and also the X-ray absorbed doses of thyroid and len when lead containing loop and spectacles of head containing glass were used for prevention.All the data were processed statistically and a compartive study of absorbed x-ray doses of four sialography methods:Doses of submandibular gland were higher in CT,tomography and fluoroscope among them,CT was the highest indicating that it was superior to other methods for accurately locating that it was superior to other methods for accurately locating the within-gland tumor.Fluoroscope will be use more frequently in clinic,because it can observe the living gland panoramic and normal radiography can be used routinely because they had the minimum doses in measured organs.2.The absorbed x-ray doses of len and thyroid decreased by 93%-% when prevention was taken in CT or fluoroscope,65%-85% doses was decreased in normal radiography or panoramic with prevention.  相似文献   
998.
通过粘度的测量,考察了壳聚糖在不同条件下经不同剂量γ射线辐照所引起的分子量的变化,并分别计算了真空和空气中壳聚糖辐射裂解的G(S)值。  相似文献   
999.
为了探索单疱病毒性角膜炎的发病机制和快速诊断HSK。方法应用多聚酶链反应对感染的HSK的20只纯新西兰白兔和60例HSK患者的角膜进行了单疱病毒-1-DNA检测。结果急性感染期的5只兔角膜和12只人角膜均阳性;用稳定期45d的兔角供体行部分穿透性角膜移植术,术后50d10只兔角膜中7只阳性,稳定期6个月-6年的18只人角膜片,12只阳性;30例临床可疑HSK角膜刮取物,26例阳性;5只未感染HSK  相似文献   
1000.
BACKGROUND--Leukotrienes are lipid mediators generated from arachidonic acid by the 5-lipoxygenase pathway which may play an important part in the pathophysiology of asthma. Previous studies have demonstrated attenuation of the allergen-induced early and late asthmatic responses by leukotriene receptor antagonists. The effect of the 5-lipoxygenase inhibitor ZD2138, a non-redox lipoxygenase inhibitor which inhibits leukotriene synthesis for 24 hours after single doses of 350 mg, on allergen-induced early and late asthmatic responses has been assessed. METHODS--Eight asthmatic subjects with baseline FEV1 > 70% were studied. On screening, all subjects developed an allergen-induced biphasic asthmatic response to grass pollen, cat dander, or house dust mite. ZD2138 (350 mg) or placebo was given on two occasions separated by two weeks in a randomised double blind fashion. Allergen inhalation challenge was performed four hours after dosing and FEV1 was measured for eight hours. The inhibitory activity of ZD2138 on the 5-lipoxygenase pathway was assessed by measurements of calcium ionophore-stimulated generation of LTB4 in whole blood ex vivo and by analysis of urinary LTE4 levels before administration of drug or placebo and at regular intervals after oral drug dosing and allergen challenge. RESULTS--ZD2138 produced no significant bronchodilatation or attenuation of the early or late asthmatic response, although there was 82% inhibition of whole blood generation of LTB4 in response to calcium ionophore stimulation and 52% reduction in urinary excretion of LTE4. CONCLUSIONS--In asthmatic subjects the 5-lipoxygenase inhibitor ZD2138 did not protect against allergen-induced asthmatic responses, despite substantial inhibition of 5-lipoxygenase.  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