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   31830篇
  免费   2751篇
  国内免费   1344篇
耳鼻咽喉   390篇
儿科学   583篇
妇产科学   570篇
基础医学   3890篇
口腔科学   542篇
临床医学   3385篇
内科学   5326篇
皮肤病学   741篇
神经病学   2124篇
特种医学   1036篇
外国民族医学   13篇
外科学   4083篇
综合类   4033篇
现状与发展   4篇
一般理论   19篇
预防医学   1909篇
眼科学   1146篇
药学   2578篇
  19篇
中国医学   1085篇
肿瘤学   2449篇
  2024年   61篇
  2023年   432篇
  2022年   932篇
  2021年   1381篇
  2020年   1029篇
  2019年   965篇
  2018年   1085篇
  2017年   954篇
  2016年   956篇
  2015年   1245篇
  2014年   1549篇
  2013年   1487篇
  2012年   2298篇
  2011年   2341篇
  2010年   1336篇
  2009年   1121篇
  2008年   1656篇
  2007年   1679篇
  2006年   1647篇
  2005年   1653篇
  2004年   1203篇
  2003年   1029篇
  2002年   917篇
  2001年   781篇
  2000年   794篇
  1999年   769篇
  1998年   430篇
  1997年   364篇
  1996年   277篇
  1995年   290篇
  1994年   232篇
  1993年   169篇
  1992年   303篇
  1991年   288篇
  1990年   279篇
  1989年   252篇
  1988年   220篇
  1987年   203篇
  1986年   197篇
  1985年   150篇
  1984年   106篇
  1983年   71篇
  1982年   49篇
  1981年   53篇
  1979年   73篇
  1978年   51篇
  1977年   52篇
  1974年   65篇
  1973年   60篇
  1972年   63篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
191.
酞丁安对映体合成及其抗单纯疱疹病毒活性评价   总被引:1,自引:0,他引:1  
酞丁安(3-酞酰亚胺-2-氧-正丁醛双缩氨硫脲,TDA)是药物研究所创制的抗病毒新药。为了研究其对映异构体(R),(S)-TDA对病毒活性及毒性是否有差异,并与消旋酞丁安(RS)-TDA的抗病毒活性及毒性进行比较,本文分别用已知构型的(R)-与(S)-丙氨酸为原料,通过缩合等6步反应,得到光学活性的(R)-,(S)-TDA,并与外消旋酞丁安比较其抗病毒活性及毒性。三者的抗单纯疱疹病毒活性与对细胞的毒性差别不大,说明消旋酞丁安临床使用是安全有效的。  相似文献   
192.
采用动脉血氧饱和度仪对52例新生儿肺炎患儿,在雾化吸入治疗过程中的动脉血氧饱和度(SaO2)进行了监测,对比了吸氧与否对SaO2改变的影响。结查表明:与基础值比较,雾化吸入时患儿的SaO2显著下降(P<0.01),而雾化吸入同时吸氧者SaO2无明显变化(P>0.05),但两者比较具有显著性差异(P<0.01)。结果提示雾化吸入可使新生儿肺炎患儿SaO2下降;同时吸氧,对防止SaO2的下降有一定作用。  相似文献   
193.
STUDY OBJECTIVES--To investigate the effects of passive exposure to tobacco smoke and gas cooking at home on respiratory symptoms and lung function of non-smoking women. SETTING--Evidence on the effects of passive smoking and exposure to nitrogen dioxide from gas cooking on the respiratory health of adults is limited and variable. Over 97% of women in Singapore do not smoke, and a principal source of indoor air pollution for housewives is passive smoking and gas cooking. DESIGN--This was a cross sectional (prevalence) study of a population based sample of 2868 adults aged 20 to 74 years in Singapore. A structured questionnaire administered by trained interviewers was used to collect data on passive smoking, gas cooking, respiratory symptoms, and other relevant variables. Passive smoking was defined as exposure to cigarette smoke from one or more members of the household who had ever smoked. Gas cooking was defined in terms of the weekly frequency of gas cooking, as well as the frequency with which the respondent's kitchen was filled with heavy cooking fumes (rarely, occasionally, often). Forced expiratory volume in one second (FEV1) was measured by using a portable Micro-spirometer. Multivariate analyses were used to estimate relative odds of association for respiratory symptoms and FEV1 effect, with adjustment for potential confounding variables. PARTICIPANTS--Of a total of 1438 women in the sample, 1282 women who had never smoked provided questionnaire data and 1008 women provided acceptable readings of FEV1 for analysis. MAIN RESULTS--Passive smoking was significantly associated with greater relative odds of usual or chronic cough and phlegm, wheezing, and breathlessness on exertion, as well as lower FEV1. Greater relative odds of respiratory symptoms were also associated with the weekly frequency of gas cooking, although these results were statistically insignificant. Chronic cough and phlegm and breathlessness on exertion, however, were significantly associated with the frequency with which the kitchen was filled with heavy cooking fumes. A lower FEV1 was found in women who cooked frequently (more than thrice a week). CONCLUSION--Domestic exposure to cigarette smoke and gas cooking is associated with increased risks of respiratory symptoms and impairment of lung function in non-smoking women in Singapore.  相似文献   
194.
195.
对照观察了以舒肝解郁,清热解毒,软坚散结,活血化瘀,益气养阴原则配伍而成的乾坤宁胶囊与复方天仙胶囊对原发性肝癌93例的临床疗效,结果表明:乾坤宁治疗组总有效率为36.84%,复方天仙组为38.88%。两组总有效率、总显效率及主要症状疗效比较均无统计学意义(P>0.05)。治疗组AFP治疗前后比较有统计学意义(P<0.05)。提示乾坤宁胶囊对原发性肝癌有一定疗效  相似文献   
196.
AmpliSensor-聚合酶链反应技术检测结核分支杆菌及临床应用   总被引:14,自引:3,他引:11  
目的探讨Amplisensor-聚合酶链反应(AmpliSensor-PCR)在结核病诊断中的价值。方法采用AmpliSensor-PCR对784例结核病患者及160例肺癌患者的标本进行检测,并与PCR(凝胶电泳后,经溴化乙锭染色)、涂片、培养等法比较。结果AmpliSensor-PCR的敏感性显著高于涂片及培养(P<0.01)。特异性较PCR法高。结论AmpliSensor-PCR可以通过标准曲线划定检出下限,并可换算出标本中原始的靶DNA值,同时具有较高的特异性和敏感性,对肺结核尤其是肺外结核的诊断有一定的临床意义。  相似文献   
197.
本文对腹腔境辅助阴式子宫切除术、阴式子宫切除术、腹式子宫切除术三组术式进行信床评价。每组10制,对其手术指征、腹腔镜组、腹式组以子宫肌瘤、卵巢肿瘤为主各为90%、100%,而阴式组则以子宫脱垂为主占100%(P值<O.001)。腹腔镜组还能同时行胆囊切除术占30%。所切除子宫大小阴式组小于正常子宫占90%。而腹腔境组、腹式组均超过正常子宫大小(P<0.001)。术后肠功能恢复在24h之内.腹腔镜组占100%、阴式组占80%、腹式组占20%(P<0.001)。腹腔境组术后无需用镇痛剂。术后住院日腹腔镜组平均5天乏与腹式组平均7.3天比较。P<0.001。得出腹腔镜辅助阴式子宫切除术兼阴式、腹式子宫切除术的优点。虽然出现2例非损伤性并发症.但只要仔细操作,该项手术在妇科手术领域有很大空间。  相似文献   
198.
Carotid endarterectomy has been established by two large randomised controlled trials (European Carotid Surgery Trial (ECST) and North American Symptomatic Carotid Endarterectomy Trial (NASCET)) as an important surgical procedure for the prevention of ischaemic strokes in patients presenting with transient cerebral ischaemia or non-disabling strokes attributable to severe ipsilateral carotid artery stenosis. The operation carries significant risk of death and stroke and it has been advocated by some that carotid endarterectomy should only be performed in a small number of designated regional centres in order to achieve good surgical results. It is doubtful that the regional centres alone can cope with the increasing numbers of patients requiring carotid endarterectomy and there is therefore a requirement for the procedure to be carried out by vascular surgeons in district general hospitals. It is important that surgical results are audited to ensure that comparable outcomes are achieved. We present an audit of our experience of carotid endarterectomy since 1981. A total of 149 consecutive carotid endarterectomies were performed by a single surgeon with a special interest in carotid surgery. The results are comparable to ECST with a 30-day mortality of 0% and an overall 30-day stroke rate of 5.7% (major strokes) for patients with severe, ie 70-99%, ipsilateral carotid artery stenoses. We have shown that carotid endarterectomy is an operation that can be performed safely and with good results by suitably trained surgeons in district general hospitals.  相似文献   
199.
对1997年以来423例病态喉的频闪喉镜表现进行分析,结果显示声带有病理改变者其粘膜波、振幅、闭合相、运动周期性、对称性均有不同程度的变化,这种变化能直接反映声带病变的深度及范围,对喉部疾病的诊断、鉴别诊断、治疗指导及预后评价具有重要意义.  相似文献   
200.
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