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   7402篇
  免费   762篇
  国内免费   16篇
耳鼻咽喉   49篇
儿科学   270篇
妇产科学   168篇
基础医学   1135篇
口腔科学   100篇
临床医学   768篇
内科学   1841篇
皮肤病学   58篇
神经病学   457篇
特种医学   457篇
外科学   1052篇
综合类   156篇
一般理论   3篇
预防医学   625篇
眼科学   81篇
药学   571篇
中国医学   9篇
肿瘤学   380篇
  2022年   47篇
  2021年   102篇
  2020年   61篇
  2019年   114篇
  2018年   108篇
  2017年   83篇
  2016年   81篇
  2015年   111篇
  2014年   154篇
  2013年   211篇
  2012年   339篇
  2011年   332篇
  2010年   191篇
  2009年   171篇
  2008年   331篇
  2007年   315篇
  2006年   343篇
  2005年   305篇
  2004年   292篇
  2003年   290篇
  2002年   330篇
  2001年   325篇
  2000年   282篇
  1999年   222篇
  1998年   105篇
  1997年   101篇
  1996年   90篇
  1995年   77篇
  1994年   65篇
  1993年   64篇
  1992年   158篇
  1991年   165篇
  1990年   141篇
  1989年   157篇
  1988年   152篇
  1987年   172篇
  1986年   146篇
  1985年   133篇
  1984年   106篇
  1983年   73篇
  1982年   70篇
  1981年   57篇
  1979年   75篇
  1978年   78篇
  1977年   68篇
  1976年   64篇
  1975年   61篇
  1974年   84篇
  1973年   69篇
  1972年   52篇
排序方式: 共有8180条查询结果,搜索用时 11 毫秒
61.
Distal humeral fractures in adults often pose a challenge to the orthopaedic surgeon. Preoperative planning, minimal devitalization of bone and soft tissue, and adherence to the prerequisites of biomechanical fixation are all important elements in effecting the desired end result. The chevron modification of the olecranon osteotomy affords excellent surgical exposure of the joint surface for fractures with an intra-articular component. When two plates are used to fix the lateral and medial distal humeral columns, it is best to orient them so that, when looked at in cross section, they are at right angles to each other. The achievement and maintenance of an anatomic reduction secure enough to permit early functional, pain-free motion of the elbow can be best ensured by open reduction and internal fixation with careful attention to detail.  相似文献   
62.
The fiberoptic panendoscope has been shown to be superior to the UGI series in diagnosing the site(s) of upper gastrointestinal bleeding (UGIB). Recent data has shown that gastritis has replaced peptic ulcer disease (PUD) as the leading cause of UGIB since the diagnosis can now be made with the endoscope. Our clinical experience differs from this. One hundred twenty five cases of UGIB from December 1975 to December 1978 were reviewed. The patients ranged in age from 11 to 91 years. There were 83 males and 42 females included in the study. Twenty-four per cent of the patients were actively bleeding at the time of endoscopic examination, and 62% received two or more units of blood. Endoscopic examination was technically successful in all patients, and there were no deaths or complications. One hundred twenty three lesions were found in 117 patients for a diagnostic accuracy of 93.9%. In eight patients, no bleeding site was found, resulting in a failure rate of 6.1%. PUD accounted for 74.9% of the bleeding sites, while gastritis accounted for only 0.8%. Mallory-Weiss tears of the esophagus accounted for 9.8% and esophageal varices for 4.9%. Thirty-five per cent of the patients had associated lesions, with gastritis and esophagitis being the most common. Eighteen patients (14.4%) required surgical intervention. Seventeen patients had PUD. There was one death, for a mortality rate of 5.5%. The medical mortality rate was 0.9%. The benefits of endoscopy in UGIB are still controversial. An important subgroup of patients with the "visible vessel" in the ulcer bed has been identified recently by others. If not bleeding at the time of endoscopy, 70% will rebleed. It is our opinion that it is important to identify this patient, as well as to know if one is treating gastritis, PUD, or varices. Finally, electrocoagulation of bleeding points, as well as the development of the laser and application of adhesives or clotting agents through the endoscope, will change the management of UGIB.  相似文献   
63.
Computed tomography (CT) was a revolution in radiology. Commercially available CT scanners appeared in 1972, a joint effort between the EMI Company, Atkinson Morley's Hospital, London and the Department of Health and Social Security (DHSS). The name of Sir Godfrey Hounsfield will always be associated with these developments. Like most developments in science the breakthrough came by standing on the shoulders of giants and many experiments can, with the curious wisdom of hindsight, be considered precursors to CT. Gabriel Frank's patent in 1940 showed apparatus for back-projection CT and Takahashi developed equipment in the 1940s for reconstructing from a sinogram; in both cases using an optical "computer". A medical CT scanner was reportedly constructed in 1957 in Kiev. Transmission CT was performed by Kuhl in 1965. Cormack built an experimental scanner in 1963. Oldendorf identified what was needed for successful CT as early as 1960. Throughout the 1960s a host of independent workers were busy on the mathematical problems of reconstructing from projections with both medical scanning and non-medical applications in mind. Experiments in early emission tomography influenced the development of CT. With imagination one can even see how close "classical" tomography, as started even before 1920, came to the realization of CT. The pioneering British radiographer Watson stands out from a galaxy of inventors. The lecture at Radiology and Oncology '91 in Brighton was a thumbnail sketch of the origins of radiological CT. A fuller story is told elsewhere (Webb, 1990).  相似文献   
64.
To determine the prevalence of "nonobstructive" (impairment of gas transfer) emphysema in a select population of smokers with dyspnea, a retrospective study of patients with emphysema evident at high-resolution computed tomography (HRCT) was undertaken. Four hundred seventy HRCT studies were reviewed. In 47 cases, centrilobular emphysema was the dominant or sole parenchymal abnormality. Concomitant chest radiographs were available in 41 of these cases; 16 of the 41 lacked radiographic findings of emphysema. Among these 16 patients, pulmonary function testing revealed 10 to have normal flow rates (ratio of forced expiratory volume in 1 second to forced vital capacity and forced expiratory volume in 1 second greater than 80% predicted) and impaired gas transfer (single-breath carbon monoxide diffusing capacity [DLCOSB] less than 80% predicted). With the exclusion of one patient with congestive heart failure from the group of 10, the severity of emphysema at HRCT correlated inversely with DLCOSB (r = -.643). These results indicate that HRCT allows detection of emphysema in symptomatic patients when chest radiographs and pulmonary function tests are nondiagnostic.  相似文献   
65.
66.
J G Im  W R Webb  M C Han  J H Park 《Radiology》1991,178(3):727-731
To elucidate the nature of the apical opacity that is commonly seen in patients with tuberculosis--usually referred to as an "apical cap" or "apical pleural thickening"--18 patients with upper lobe tuberculosis were studied with high-resolution computed tomography (HRCT). All had a homogeneous apical opacity at least 1 cm thick on chest radiographs. Fifteen of the 18 had a history of pulmonary tuberculosis of more than 5 years duration, and nine showed evidence of ipsilateral pleurisy. HRCT scans at the apex of the thorax in all nine patients scanned at this level showed that extrapleural fat with interspersed vessels accounted for most of the plain radiographic opacity. Scans obtained at a level slightly above visible aerated lung showed extrapleural fat 3-25 mm thick peripherally and atelectatic lung centrally. At more caudal levels, at which both aerated lung and "thickened pleura" were visible on plain radiographs, HRCT showed extrapleural fat (3-20 mm thick), thickened pleura (1-3 mm thick), and atelectatic lung peripherally and areas of emphysematous bullae, bronchiectasis, and atelectatic lung centrally.  相似文献   
67.
Delegation     
Webb DM 《Hospital topics》1991,69(4):40-41
  相似文献   
68.
P Webb 《The Journal of nutrition》1991,121(11):1897-1901
This is a brief account of the development of energy expenditure measurements, from speculations by early philosophers on the nature of the "innate fire," through the beginnings of quantitative animal calorimetry and to the combined material and energy balances of Rubner and of Atwater and Benedict, which established the science of nutritional energy. The equivalence of oxidation rate and heat loss led to the simplification of indirect calorimetry, followed by the era of studies of basal metabolic rate. Current practices are reviewed for measuring energy expenditure by indirect calorimetry (respiration chambers, ventilated hoods, doubly labeled water) and direct calorimetry (rooms, suits). Because problems remain in the exact account of energy balance during weight change, growth, pregnancy and exercise, perhaps it may be time to combine once again carbon balance with energy balance, using modern methods.  相似文献   
69.
Protection of the solitary testis   总被引:1,自引:0,他引:1  
In 15 negative explorations for unilateral cryptorchidism, inspection of the contralateral scrotum revealed a "bell-clapper" deformity in 13 patients. Since the descent of the testis is influenced by the gubernaculum and gubernacular abnormalities are usually bilateral, the data suggest that an inadequate gubernaculum is associated with most instances of antenatal and postnatal torsion. Unilateral absence of the testis is a form of this syndrome; congenital monorchidism is probably due to antenatal torsion rather than hypoplasia or agenesis. When monorchidism is confirmed at operation, exploration and suture fixation of the contralateral testis at the same procedure is recommended to protect the solitary testis from future torsion.  相似文献   
70.
Summary This paper discusses the relationship between pharmacy and medicine in the light of recent claims that occupations such as pharmacy, whose central tasks arc organised around those of medicine, have gained increasing control over their sphere of work, thus contributing to a decline in medical hegemony. We discuss the process by which on the one hand, para-medical groups may extend their boundaries into areas officially the responsibility of the medical profession, and on the other, the medical profession may willingly delegate or indeed relinquish control over certain tasks. However, we argue from data collected from those groups in medicine and pharmacy concerned with the problems of drug use, that this does not necessarily indicate a decline in medical hegemony.  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