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   19348篇
  免费   1576篇
  国内免费   550篇
耳鼻咽喉   70篇
儿科学   344篇
妇产科学   262篇
基础医学   1268篇
口腔科学   781篇
临床医学   2080篇
内科学   4663篇
皮肤病学   90篇
神经病学   1395篇
特种医学   1792篇
外国民族医学   3篇
外科学   2305篇
综合类   2524篇
现状与发展   1篇
预防医学   358篇
眼科学   1282篇
药学   1263篇
  7篇
中国医学   400篇
肿瘤学   586篇
  2024年   23篇
  2023年   349篇
  2022年   502篇
  2021年   901篇
  2020年   831篇
  2019年   847篇
  2018年   830篇
  2017年   735篇
  2016年   697篇
  2015年   766篇
  2014年   1228篇
  2013年   1431篇
  2012年   981篇
  2011年   1121篇
  2010年   920篇
  2009年   958篇
  2008年   882篇
  2007年   932篇
  2006年   801篇
  2005年   654篇
  2004年   541篇
  2003年   501篇
  2002年   408篇
  2001年   382篇
  2000年   293篇
  1999年   260篇
  1998年   274篇
  1997年   225篇
  1996年   219篇
  1995年   207篇
  1994年   223篇
  1993年   172篇
  1992年   141篇
  1991年   131篇
  1990年   108篇
  1989年   111篇
  1988年   82篇
  1987年   85篇
  1986年   83篇
  1985年   102篇
  1984年   97篇
  1983年   48篇
  1982年   72篇
  1981年   72篇
  1980年   60篇
  1979年   39篇
  1978年   47篇
  1977年   28篇
  1976年   24篇
  1974年   14篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
For its peripheral vascular dilating effect and platelet agglutination inhibitory activity, prostaglandin E1 is used in the treatment of diseases which are likely to cause peripheral circulatory failure or thrombus. In Japan, lipo-PGE1, which was developed to give it a target-directed nature by modifying the conventional PGE1, has been used and found to be useful in clinical practice. In this report, we attempt to describe the clinical benefits of lipo-PGE1 focusing on the diseases which have been approved for its indications.  相似文献   
83.
Reflex haemodynamic responses to orthostatic stress are attenuated with ageing, the extent of attenuation increasing with advancing age. In 15–20% of individuals aged >65 years, the attenuation may be so marked that there is an excessive fall of blood pressure (BP) on assumption of the upright posture, sufficient on occasions to cause symptomatic cerebral hypoperfusion - this is known as ‘ageing-related’ orthostatic hypotension (AOH), a major risk factor for morbidity and mortality. Comparison of the cardiovascular responses to a variety of physiological and pharmacological stresses in healthy young and elderly subjects and in those with AOH suggests that the predominant site of the ageing-related change in cardiovascular reflex function is in the central connections of the arterial baroreflex, affecting particularly the BP buffering response. There is no evidence for ageing-related impairment of the efferent limb of the baroreflex, i. e. there is no significant ageing change in sympathetic vasomotor function or cardiac drive. Ageing-related impairment of baroreflex function also does not appear to result from either attenuation of arterial compliance or the presence of systolic hypertension, despite the epidemiological association between systolic hypertension and AOH. Better understanding of this important problem has the potential to improve the health of all elderly people.  相似文献   
84.
A case of insulinoma is reported in a patient in whom selective arterial calcium injection (SACI) tests were performed both to confirm tumor localization before surgery and to confirm complete tumor removal during surgery. An 18-year-old woman with hypoglycemic episodes was diagnosed with an insulinoma in the pancreatic body demonstrated by celiac arteriography. In a preoperative SACI test, calcium was injected into the splenic artery (SpA), gastroduodenal artery (GDA), and superior mesenteric artery (SMA). Serum immunoreactive insulin (IRI) and proinsulin levels were measured in hepatic venous samples. IRI was markedly increased after the injection of calcium into the GDA and SMA, while there was no response in IRI levels when calcium was injected into the SpA. Therefore, no occult insulinoma was revealed in the distal area fed by the SpA, although the presence of insulinoma was uncertain in the proximal pancreas. In the intraoperative SACI test, calcium was injected into the celiac artery. Insulin (determined by enzyme immunoassay) and proinsulin levels were measured in portal venous samples before and after resection of the tumor. After resection, these levels decreased in response to the calcium stimuli, confirming complete removal of the insulinoma. The SACI test was helpful to localize the insulinoma and was useful to confirm the complete removal of the tumor.  相似文献   
85.
目的建立重庆市正常牙合青少年牙颌模型牙列指数的正常值,为正畸临床提供依据.方法选取重庆市正常牙合青少年牙颌模型92付(男45付,女47付),测量牙冠宽度、牙弓宽度,计算Bolton指数和Pont指数,对测量结果进行统计分析并与国内外相关资料进行对比研究,对Bolton指数和Pont指数的临床应用价值进行评价.结果Bolton指数和Pont指数存在种族和地区差异,结论Bolton指数和Pont指数在正畸临床中均有一定的应用价值,临床上应参照本民族和地区的标准.  相似文献   
86.
We present a patient with vertebrobasilar insufficiency, with vertigo and horizontal nystagmus, induced by turning the head to the right. Angiography demonstrated transient occlusion of the left vertebral artery at the atlantoaxial joint during rotation of the head. The pathogenesis and angiographic findings are discussed.  相似文献   
87.
Objective. The objective of this study was to compare blood pressure (BP) measured by the sphygmooscillographic method with that measured by the direct and auscultatory methods.Methods. In 15 adult patients undergoing cardiac surgery, blood pressure was measured by the sphygmooscillographic and direct methods simultaneously on the same upper extremity. In another group of 86 children and 11 adults, blood pressure was measured by the sphygmooscillographic and auscultatory methods simultaneously, with one cuff. For the sphygmooscillographic measurement, we used sphygmomanometer-S, which measures blood pressure on the basis of the amplitude height (oscillometric) and the morphology (sphygmographic) of pulse waves recorded by a transducer placed in the cuff.Results. The systolic and diastolic blood pressure measured by the sphygmooscillographic method were both 2 mm Hg higher than those from the direct method; the mean blood pressure was 0.6 mm Hg higher. These differences were not significant. Compared with the auscultatory method, sphygmooscillographic systolic values were higher by 7 mm Hg, while diastolic values were lower by 9 mm Hg. These differences were significant.Conclusions. Blood pressure measurements obtained by the sphygmooscillographic method correlate well with the direct method for measuring blood pressure in children and adults; but, they do not correlate well with the auscultatory method.  相似文献   
88.
L- Tetrahydropalmatine (L- THP) ,a kind of al-kaloid extracted from traditional Chinese medicineRhizoma corydalis,posseses sedative,analgesic andhypnotic effects.Recently,it has been demonstratedthat L- THPalso had calcium- antagonistic and antiar-rythmic effects.Studies showed that L- THP had aprotective effect on acute focal and global cerebral is-chemia- reperfusion injury[1,2 ] .Many studies provedthat the production of NO wasincreased significantlyduring ischemia- reperfusion.The o…  相似文献   
89.
矽肺患者肺功能与动脉血气分析的研究   总被引:6,自引:1,他引:5       下载免费PDF全文
本文对88例矽肺病人和37名接尘工人进行了肺功能和动脉血气分析,结果表明各期矽肺的VC、FVC、FEV_1、MMF、FEV_1/FVC均值低于接尘组,而异常检出率则高于接尘组,通气功能的下降呈进行性,但早期不很明显,与接尘组无显著差异。各期矽肺组V_(50)及V_(25)均有明显降低,显示早期即有小气道的广泛损害。矽肺的通气功能损害类型,Ⅰ期矽肺组以阻塞型多见,Ⅱ、Ⅲ期矽肺组以混合型为主。RV和RV/TLC在Ⅲ期矽肺组有明显增高,表明矽肺晚期多并发肺气肿。另外DL_(CD)和K_(CD)在各矽肺组均低于接尘组,差异有显著性,说明矽肺早期即可有弥散功能的损害。血气分析表明PaO_2及SatO_2降低主要见于Ⅱ、Ⅲ期矽肺。Ⅲ期矽肺组有1/3患者(33.33%)在有低氧血症的同时合并有高碳酸血症。对比肺功能和血气分析结果,认为通气功能指标FEV_1、FEV_1/FVC、VC、FVC、MMF以及弥散功能指标DL_(CO)和K_(CO)为早期反映矽肺呼吸功能的灵敏指标。血气分析对病情和预后的判断有重要参考价值。  相似文献   
90.
电刺激膈神经中枢端引起降压反应的外周机理   总被引:1,自引:0,他引:1  
电刺激麻醉家兔膈神经中枢端呆引起动脉血压下降,此降压反应不能被剪断双侧迷走神经所阻断;但可被静脉注射心得1.0mg/kg部分阻断;也可被静注射酚妥拉明2.0mg/kg部分阻断,去除缓冲神经后其降压效应更为明显。  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