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   9945篇
  免费   1039篇
  国内免费   25篇
耳鼻咽喉   69篇
儿科学   252篇
妇产科学   297篇
基础医学   1462篇
口腔科学   295篇
临床医学   939篇
内科学   1679篇
皮肤病学   237篇
神经病学   677篇
特种医学   764篇
外科学   1571篇
综合类   277篇
一般理论   7篇
预防医学   1006篇
眼科学   220篇
药学   577篇
  1篇
中国医学   2篇
肿瘤学   677篇
  2021年   129篇
  2020年   84篇
  2019年   170篇
  2018年   172篇
  2017年   123篇
  2016年   131篇
  2015年   162篇
  2014年   202篇
  2013年   310篇
  2012年   402篇
  2011年   420篇
  2010年   276篇
  2009年   310篇
  2008年   435篇
  2007年   423篇
  2006年   447篇
  2005年   423篇
  2004年   364篇
  2003年   349篇
  2002年   331篇
  2001年   307篇
  2000年   300篇
  1999年   271篇
  1998年   193篇
  1997年   184篇
  1996年   177篇
  1995年   176篇
  1994年   135篇
  1993年   136篇
  1992年   228篇
  1991年   220篇
  1990年   198篇
  1989年   250篇
  1988年   185篇
  1987年   211篇
  1986年   183篇
  1985年   194篇
  1984年   148篇
  1983年   127篇
  1982年   109篇
  1981年   71篇
  1980年   82篇
  1979年   117篇
  1978年   81篇
  1977年   82篇
  1976年   70篇
  1975年   64篇
  1974年   74篇
  1973年   70篇
  1968年   63篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
A lump on the midface of a child can pose as a diagnostic dilemma. There is a wide variety of possible differential diagnoses, ranging from simple benign conditions such as a sebaceous cyst, dermoid cyst, lipoma, neuroma and neurofibroma, to potentially devastating conditions such as odontogenic myxoma.A case of a child in which the formulation of a definite diagnosis was clinically and histologically challenging is presented.  相似文献   
32.
PURPOSE: We undertook a feasibility study to explore the prevalence of preoperative and postoperative lower urinary tract symptoms (LUTS) in older adults undergoing elective hip arthroplasty and to determine whether a larger prospective study was warranted. METHOD: Subjects awaiting elective hip arthroplasty were recruited preoperatively from an orthopedic office and preadmission clinic at 1 university-affiliated hospital. LUTS and related quality of life were measured prehospitalization and 6 weeks postoperatively using the American Urological Association Symptom Index and quality-of-life score. Postvoid residual urine and the 24-hour pad test were used to assess bladder emptying and continence status. RESULTS: Sixteen participants (9 males, 7 females, mean age 74 years) completed the study. Preoperatively, 15 participants reported at least 1 symptom and none had discussed these with a healthcare professional. The most common LUTS were nocturia, frequency, and urgency. Postoperatively, all reported symptoms, with 8 (53%) experiencing increased symptoms with a negative impact on quality of life for 3. Recruitment was a major barrier in conducting the study and would need to be taken into account in further studies of the topic. CONCLUSION: Despite recruitment issues, we suggest larger studies of LUTS in older adults undergoing surgery are warranted to further understand potential problems and risks in transition from hospital to home. Future studies should include identification of potential reasons for increased LUTS, including urinary tract infection.  相似文献   
33.
Greater Cape Town has developed a geographical network of perinatal health care services for low-income mothers using community-based clinics with hospital referrals. This study analyzes 25,409 births recorded in 162 different urban residential areas during 1987. The data apply to two populations--black and mixed. Information on the mother, such as height, weight, education, parity, and prenatal visits is indicated by suburb, as well as birth outcomes such as gestational age, birthweight, and method of obstetrical delivery. Comparisons are drawn between black and mixed populations and among suburbs. High utilization rates and successful maternity and infant outcomes suggest that the outreach clinics of Cape Town could provide a model for urban agglomerations in other African countries.  相似文献   
34.
The public sector in Britain has been subjected to over a decade of major reform aimed at breaking up public service monopolies, at containing costs while at the same time opening services up to greater consumer choice. Health and social services have not been exempt from this revolution in the organization and management of public sector services. The long-standing policy of care in the community is being subjected to market principles and the introduction of a ‘contract culture’ very similar to the NHS reforms introduced in 1991. This paper reviews the origins of these developments in the doctrines of ‘new public management’, a movement which has proved attractive to policy-makers in many countries. Local authority social services departments have been identified as the lead agency for the development of a mixed economy of care following a review of community care policy by the government's health adviser, Sir Roy Griffiths, and a subsequent white paper. This paper examines the limited empirical evidence available on how managers and providers are meeting the challenge bestowed upon them, and concludes that most authorities are moving ahead cautiously if at all. Only a handful of authorities studied have embraced the reforms with any degree of enthusiasm. The paper concludes with an assessment of the reforms from two perspectives: a pessimistic one and an optimistic one. There are many worrying features of the reforms, not least among these being a lack of clarity over their intended purpose. Tensions and contradictions are plentiful, which places in jeopardy the certainty of the reforms in becoming user led rather than provider driven. A more optimistic scenario is that the changes are leading to a loosening up of services and practices which have often suffered from sclerotic tendencies, paternalism and sometimes complacency. If the reform process is skilfully handled and not rushed and if the ends are clearly established and communicated then users and carers could prove to be the principal beneficiaries.  相似文献   
35.
36.
The aim of this study was to assess the accuracy of technetium 99m-labeled red cell scintigraphy in localizing the site of lower gastrointestinal bleeding. The outcome of 203 patients undergoing technetium 99m-labeled red cell scintigraphy was reviewed, and the scan result was compared with the true site of bleeding. The true site of bleeding was determined by other methods including angiography and surgical pathology. Fifty-two scans (26%) were positive and indicated a specific site of bleeding. A definitive bleeding site was identified in 22 patients by other means and correlated with the technetium scan in only 9 cases. The nuclear scan was incorrect in the remaining 13 cases, implying a localization error of 25% (13 of 52). A subgroup of 19 patients with a positive scan underwent a surgical procedure directed by the nuclear scan. Eight of these 12 patients had incorrect surgical procedures based upon findings of more definitive tests, indicating a surgical error of 42% (8 of 19). We conclude that the technetium 99m-labeled red cell scan's ability to accurately localize the site of lower gastrointestinal bleeding is limited. Furthermore, performing a surgical procedure that relies exclusively on localization by red cell scintigraphy will produce an undesirable result in at least 42% of patients.  相似文献   
37.
38.
The ureteral access set was used 43 times during an 18-month period between 1984 and 1985. Stones lodged throughout the ureter and in the renal pelvis were extracted with a success rate of 51 per cent. Of the upper tract strictures 92 per cent were dilated successfully. Filling defects were diagnosed in 88 per cent of the cases. Foreign bodies were retrieved, Double-J stents were placed and biopsies were successful in each case. Ureteral perforation in 28 per cent of the cases was caused by the dilator in 8 of 12 (19 per cent over-all). The technique and short-term results are discussed. Long-term followup data are not yet available.  相似文献   
39.
P-glycoprotein expression was demonstrated in two human intestinal adenocarcinoma cell-lines (HCT-8, ileocaecal and T84, colonic) by immunoprecipitation of a 170-180 kDa protein with monoclonal antibody JSB-1. Both HCT-8 and T84 formed functional epithelial cell layers of high transepithelial electrical resistance (greater than 700 omega.cm2) when grown on permeable matrices. These epithelial layers demonstrated vectorial secretion (net vinblastine fluxes in the basal-to-apical direction of 0.135 and 0.452 pmol h-1 cm-2 in HCT-8 and T84 cell layers, respectively, from bathing solutions containing 10 nM vinblastine). These vectorial vinblastine secretions were sensitive to inhibition by verapamil. Passive transepithelial vinblastine permeation was limited by the presence of intercellular (tight) junctions, as demonstrated by the high transepithelial electrical resistance, and verapamil increased this passive vinblastine permeation concomitant with a reduction in the electrical resistance. Cellular vinblastine loading was significantly greater from the basal side, and this was also susceptible to inhibition by basal verapamil. The demonstration of vectorial transport of vinblastine in human intestinal colonic adenocarcinoma cell layers is direct evidence in favour of the hypothesis that the function of mdr1 in epithelial from the gastrointestinal tract is to promote detoxification by a process of epithelial secretion. This study also highlights that cellular vinblastine accumulation depends not only upon P-glycoprotein function, but also upon differential apparent membrane permeabilities and the presence of intercellular (tight) junctions that may restrict drug permeation and cellular accumulation to apical or basal membrane domains.  相似文献   
40.
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