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   13396篇
  免费   724篇
  国内免费   95篇
耳鼻咽喉   90篇
儿科学   229篇
妇产科学   125篇
基础医学   2173篇
口腔科学   100篇
临床医学   1372篇
内科学   2960篇
皮肤病学   388篇
神经病学   1309篇
特种医学   526篇
外科学   2029篇
综合类   49篇
一般理论   2篇
预防医学   664篇
眼科学   217篇
药学   957篇
中国医学   40篇
肿瘤学   985篇
  2023年   63篇
  2022年   85篇
  2021年   259篇
  2020年   155篇
  2019年   231篇
  2018年   325篇
  2017年   205篇
  2016年   246篇
  2015年   271篇
  2014年   378篇
  2013年   518篇
  2012年   910篇
  2011年   1025篇
  2010年   607篇
  2009年   536篇
  2008年   873篇
  2007年   1018篇
  2006年   911篇
  2005年   947篇
  2004年   886篇
  2003年   865篇
  2002年   849篇
  2001年   135篇
  2000年   104篇
  1999年   147篇
  1998年   213篇
  1997年   165篇
  1996年   163篇
  1995年   111篇
  1994年   111篇
  1993年   110篇
  1992年   99篇
  1991年   59篇
  1990年   50篇
  1989年   63篇
  1988年   51篇
  1987年   46篇
  1986年   50篇
  1985年   31篇
  1984年   51篇
  1983年   42篇
  1982年   47篇
  1981年   32篇
  1980年   35篇
  1979年   25篇
  1978年   23篇
  1977年   16篇
  1976年   12篇
  1975年   9篇
  1974年   12篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
We report two patients with ipsilateral attacks of cluster headache and chronic paroxysmal hemicrania. The first patient, a 33-year-old man, started having attacks of chronic cluster headache at the age of 27. At 33, they were replaced by typical attacks of ipsilateral chronic paroxysmal hemicrania which showed a dramatic improvement with indomethacin 150 mg daily. After two days of complete remission, cluster headache attacks reappeared and persisted until verapamil, 360 mg a day, was added to indomethacin. The second patient, a 45-year-old man, first developed attacks of episodic cluster headache at the age of 35. At 44, he experienced ipsilateral typical attacks of chronic paroxysmal hemicrania, and two months later attacks of cluster headache. Under verapamil 240 mg daily, attacks of cluster headache disappeared, but those of chronic paroxysmal hemicrania increased in frequency until indomethacin 150 mg daily was added. These observations suggest a close relationship but not a similarity between cluster headache and chronic paraoxysmal hemicrania, and show the practical therapeutic interest of maintaining this distinction.  相似文献   
22.
23.
24.
This case report illustrates atypical magnetic resonance (MR) imaging findings in a liver hemangioma mimicking a malignant lesion—lower signal intensity than cerebrospinal fluid on T2-weighted spin-echo images and lack of early enhancement on dynamic contrast material—enhanced gradient-echo images. Pathologic analysis demonstrated nearly total replacement of the vascular cavities by dense fibrous tissue. In this rare, sclerosed form, this lesion could not be defined as a hemangioma with MR imaging.  相似文献   
25.
Evaluative composite measurement scales (CMS) are increasingly used in medicine to measure complex constructs in the absence of a reference criterion or ‘gold standard’. However, the level of measurement provided by these instruments has usually been given little attention. This paper explores the influence of the characteristics of the item set and weighting on the level of measurment of an evaluative CMS. The approach is illustrated with an application to the scoring system of the Nottingham Health Profile. Simulations are provided to indicate when the composite score of item responses, on an ordinal or pass—fail scale, could be considered to achieve the properties of an interval scale.  相似文献   
26.
A 28-year-old mentally retarded, institutionalised woman was referred to us for evaluation of multiple plantar warts and ingrown nails of both great toes. The patient was born to unrelated parents of North African origin and had one brother and three half-brothers, all of whom were healthy. Physical examination revealed short stature, slight obesity, facial abnormalities (Fig. 1), short and broad thumbs and big toes (Figs. 2 and 3). A keloid was found on the right forearm, that had developed after surgical correction of a fracture (Fig. 4). Ill-defined hyperpigmented macules were observed on the trunk. The patient also presented pruritic eczematous lesions of the limbs and the back that had been present for some years and were recurrent despite treatment with emollients and local steroids. Androgenetic-type alopecia of moderate severity was seen on the vertex of the scalp. Past medical history included polydactylism of the feet and clinodactyly of the thumbs (both corrected surgically), respiratory tract infections, Wolf-Parkinson-White syndrome and refractive errors necessitating glasses.  相似文献   
27.
The polymerization of lactides with various D /L enantiomeric compositions using achiral Schiff's base/aluminium methoxide as initiator (SALENAlOCH3) in dichloromethane solution at 70°C is reported. The conversion was kept below 70% in order to limit transesterification reactions. The polymers obtained after precipitation show a narrow molecular weight distribution (ratio of weight- to number-average molecular weights M w/M n = 1,1–1,2) and an optical rotation higher than that expected from the optical purity of the starting monomers. The examination of the thermal properties reveals that whatever their enantiomeric composition all the prepared polymers are crystalline. This unusual behavior is explained by an end-chain propagation mechanism producing stereocopolymers with long enantiomeric sequences, i.e., increased isotacticity as substantiated by an examination of the microstructure of the polymers by means of 13C nuclear magnetic resonance. A stereocomplex formation was observed for stereocopolymers with optical purities below 40%.  相似文献   
28.
The diagnosis of nontraumatic intracranial hemorrhage is currently made by computed tomography and is rarely problematic. The causes of bleeding are very numerous. It is important to determine the cause of the hemorrhage promptly, because there may be a recurrence of bleeding. Guidelines for radiologists are proposed and discussed here.  相似文献   
29.
OBJECTIVES: This article examines the differences found between clientele with severe mental health problems and their key health workers in terms of assessing service users' needs in 6 Quebec service areas. METHOD: We questioned 165 pairs of users and staff, using the Camberwell Assessment of Needs questionnaire. The profile of serious and overall problems encountered by clientele from each of the sites was compared. RESULTS: The sites with the greatest degree of user-staff agreement in identifying problems were also the ones where users considered that local services best met their needs. CONCLUSIONS: The study demonstrated that, in needs assessment, major differences exist between the perceptions of users and their key workers in the various sites. These differences can be explained in part by users' individual characteristics, by types of needs, by local particularities, and by service use.  相似文献   
30.
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