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   909篇
  免费   59篇
  国内免费   45篇
耳鼻咽喉   2篇
儿科学   42篇
妇产科学   15篇
基础医学   101篇
口腔科学   40篇
临床医学   127篇
内科学   225篇
皮肤病学   27篇
神经病学   37篇
特种医学   136篇
外科学   65篇
综合类   17篇
预防医学   36篇
眼科学   6篇
药学   71篇
中国医学   10篇
肿瘤学   56篇
  2023年   3篇
  2022年   3篇
  2021年   12篇
  2020年   4篇
  2019年   14篇
  2018年   29篇
  2017年   9篇
  2016年   12篇
  2015年   13篇
  2014年   26篇
  2013年   31篇
  2012年   27篇
  2011年   35篇
  2010年   40篇
  2009年   33篇
  2008年   38篇
  2007年   60篇
  2006年   32篇
  2005年   31篇
  2004年   16篇
  2003年   22篇
  2002年   12篇
  2001年   17篇
  2000年   21篇
  1999年   20篇
  1998年   48篇
  1997年   35篇
  1996年   37篇
  1995年   24篇
  1994年   20篇
  1993年   22篇
  1992年   20篇
  1991年   14篇
  1990年   22篇
  1989年   32篇
  1988年   34篇
  1987年   24篇
  1986年   23篇
  1985年   15篇
  1984年   8篇
  1983年   10篇
  1982年   10篇
  1981年   6篇
  1980年   7篇
  1979年   3篇
  1978年   7篇
  1977年   11篇
  1976年   6篇
  1975年   6篇
  1974年   3篇
排序方式: 共有1013条查询结果,搜索用时 187 毫秒
51.
ABSTRACT We report an unusual case of bilateral chronic conjunctivitis and corneal scarring in a boy with X-linked hypogammaglobulinaemia (XLH) who did not respond to the usual antibacterial and antiviral therapy. An immunofluorescence test for Chlamydia trachomatis from an eye swab was strongly positive. Within days of commencement of local and systemic tetracycline therapy, he showed marked improvement. Since conjunctival follicle formation, which depends on the presence of a B-cell population, may not occur in XLH, clinical examination in chlamydia conjunctivitis may be misleading and lead to a delay in diagnosis and treatment with resulting corneal complications, unless laboratory evidence of chlamydia infection is specifically sought.  相似文献   
52.
Objective : To describe survival patterns, use of health services and related costs for Australian children with perinatally acquired human immunodeficiency virus (HIV) infection.
Methodology : A retrospective cross-sectional survey was made of 20 children with HIV infection (91% of those diagnosed) and 13 children with maternal antibodies who subsequently seroreverted, treated at 10 medical centres. Details of disease progression and use of health services were obtained from hospital medical records. Monthly costs for three phases of infection were estimated by linking service usage rates with estimates of the unit cost of each service. The average lifetime cost was estimated by combining monthly costs and phase duration estimates from the literature.
Results : Patterns of disease progression were similar to those reported internationally, with a median survival of 8 years. Use, of health services increased with severity of illness. Mean monthly costs were $120 per month (1992 Australian dollars) for children with maternal antibodies who subsequently seroreverted, $320 per month for children with HIV infection but no acquired immunodeficiency syndrome (AIDS)-defining illness, and $1830 per month for children with AIDS. The present value of total lifetime cost for a child with HIV infection was $48174,46% of which was for treatment of AIDS.
Discussion : The mean lifetime cost for a perinatally infected child was just over half that for a man with HIV in Australia. Health service usage and costs were lower for Australian than American children with HIV.  相似文献   
53.
54.
BACKGROUND: Proton pump inhibitors are known to decrease the activity of Helicobacter pylori organisms within the stomach and to shift their distribution proximally. This effect may reduce the sensitivity of histological examination and rapid urease testing for H. pylori on biopsies taken from recommended sites. It is of particular relevance if a proton pump inhibitor has been prescribed before the patient has undergone diagnostic endoscopy. METHODS: We studied patients referred to our open-access upper gastrointestinal endoscopy service who had either been on no medication (controls) or were already taking proton pump inhibitors. Biopsies taken from the gastric antrum and corpus were used for rapid urease testing and for histological examination. Sera, taken from patients who had no evidence of H. pylori in biopsies, were tested for IgG H. pylori antibodies as an alternative indicator of infection. RESULTS: H. pylori organisms were detected by histological examination in 27 of 40 controls (68%) and in 13 of 25 patients taking proton pump inhibitors (52%). Among patients with positive histology (organisms detected in either antral or corpus biopsies, or both), only the sensitivity of the antral urease test read at 1 h was significantly lower in patients taking proton pump inhibitors than in controls, with no significant difference in sensitivities of the antral urease test at 24 h, of the corpus urease test at 1 or 24 h, or of histology from the antrum or corpus. Of patients with negative histology, none of 13 controls compared with six of 12 patients taking proton pump inhibitors (50%) had positive serology (P = 0.005). Five (83%) of the six histology-negative, seropositive patients taking proton pump inhibitors had histological changes consistent with H. pylori gastritis even though no organisms were detected. CONCLUSIONS: Treatment with a proton pump inhibitor before endoscopy reduces the sensitivity of antral and corpus biopsies for H. pylori detection, both by urease testing and histological examination. If proton pump inhibitors already prescribed cannot be discontinued for an adequate period before endoscopy, patients should have biopsies taken from the corpus as well as from the antrum, and serum should be tested for H. pylori.  相似文献   
55.
Both ultrasonography (US) and cholescintigraphy are used to study gallbladder dynamics. The present study was undertaken to determine whether the two methods provide the same or different information relating to gallbladder emptying. Emptying was simultaneously studied with both methods during infusion of graded physiologic doses of cholecystokinin (CCK) in six healthy subjects. Infusion of stepwise increasing doses of CCK, ranging from 0.03 to 0.5 Ivy dog units per kilogram of body weight per hour (IDU/kg.h), induced significant dose-related increases in plasma CCK, decreases in gallbladder volume assessed with US, and gallbladder emptying assessed with cholescintigraphy. The threshold dose for inducing significant gallbladder emptying was 0.13 IDU/kg.h, as determined with both techniques, indicating similar detection limits. There was a highly significant correlation between decreases in gallbladder volume and decreases in radioactive counts over the gallbladder region, with a tendency toward greater gallbladder responses at sonography during the early phase of gallbladder contraction and toward greater responses at cholescintigraphy during the later phase of gallbladder contraction. It is concluded that these methods can be used interchangeably for the quantitation of gallbladder emptying.  相似文献   
56.
57.
The following article briefly sets out the possible new protocols that can be applied in biliary pathology, arising from the changes brought about by the appearance of new techniques of laparoscopic biliary surgery. It offers a synthesis of the latest and most novel articles on surgical technique and management in different biliary pathologies such as choledocholithiasis and cholecystitis. It can be concluded that management will differ greatly, depending on the technical capacities of the centre that is called upon to deal with one of these pathologies. A standard protocol for everybody cannot thus be established at present. The differences between endoscopic retrograde cholangiopancreatography and intraoperative laparoscopic cholangiography have still to be demonstrated, it is not possible to make generalisations about whether one technique is more useful than the other. The same could be said about whether access to the main biliary path should be achieved through the cystic conduct or whether, on the contrary, a choledochotomy should be performed.  相似文献   
58.
Nosocomial infection is regarded as a serious problem whose incidence and complexity has been increasing, thus generating various types of social and economic implications. This investigation aimed at assessing the incidence of surgical site infection and risk factors in patients submitted to elective surgeries in the specialty of gastroenterology performed in a public hospital in the interior of S?o Paulo State. Data were collected by means of a retrospective study of medical records from January to December 1999. Of the 134 cases under study, the occurrence of surgery site infection was detected in 18 situations (13.4%). Nine cases (50%) were considered to be superficial incisional infections, 8 (44.4%) were deep incisional infections and 1 (5.5%) was an organ/space infection. With respect to the risk factors, the ones with percentage higher or equal to 50% were: age above 50 years, the presence of neoplasia, surgeries that last more than two hours and inadequate trichotomy.  相似文献   
59.
Fractionation of an ethanolic extract of the leaves of Phenax angustifolius has resulted in the isolation of two new lignans, 2-hydroxy-2-(3',4'-dihydroxyphenyl)methyl-3-(3' ',4' '-dimethoxyphenyl)methyl-gamma-butyrolactone (1) and 2-hydroxy-2-(4'-O-beta-D-glucopyranosyl-3'-hydroxyphenyl)methyl-3-(3' ',4' '-dimethoxyphenyl)methyl-gamma-butyrolactone (2), and three known compounds, vitexin, isovitexin, and quercetin 3-O-alpha-L-rhamnopyranoside. The structures of 1 and 2 were determined using spectroscopic methods.  相似文献   
60.
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