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   19617篇
  免费   2048篇
  国内免费   54篇
耳鼻咽喉   164篇
儿科学   549篇
妇产科学   511篇
基础医学   2649篇
口腔科学   374篇
临床医学   2167篇
内科学   3921篇
皮肤病学   200篇
神经病学   2046篇
特种医学   864篇
外科学   2833篇
综合类   483篇
一般理论   14篇
预防医学   1869篇
眼科学   278篇
药学   1234篇
  1篇
中国医学   5篇
肿瘤学   1557篇
  2021年   265篇
  2020年   168篇
  2019年   269篇
  2018年   307篇
  2017年   243篇
  2016年   269篇
  2015年   284篇
  2014年   399篇
  2013年   687篇
  2012年   878篇
  2011年   946篇
  2010年   518篇
  2009年   580篇
  2008年   841篇
  2007年   901篇
  2006年   859篇
  2005年   923篇
  2004年   857篇
  2003年   796篇
  2002年   772篇
  2001年   634篇
  2000年   658篇
  1999年   609篇
  1998年   290篇
  1997年   250篇
  1996年   258篇
  1995年   208篇
  1994年   216篇
  1993年   202篇
  1992年   438篇
  1991年   426篇
  1990年   415篇
  1989年   449篇
  1988年   360篇
  1987年   362篇
  1986年   358篇
  1985年   326篇
  1984年   257篇
  1983年   211篇
  1982年   182篇
  1981年   153篇
  1980年   139篇
  1979年   213篇
  1978年   180篇
  1977年   149篇
  1976年   146篇
  1974年   177篇
  1973年   139篇
  1972年   152篇
  1971年   139篇
排序方式: 共有10000条查询结果,搜索用时 279 毫秒
51.
Ten thrombocytopenic patients (platelets < 10–24 × 10(9)/L) who were refractory to platelet transfusion were investigated for their responsiveness to staphylococcal protein A column therapy. Nine patients had previously been treated with steroids, intravenous immune globulin, and/or other forms of immunosuppressive therapy without improvement in their transfusion response. All patients were receiving multiple platelet transfusions without achieving 1-hour corrected count increments (CCIs) > or = 7500. Eight patients had antibodies that reacted with platelets and were directed against HLA class I antigens, ABO antigens, and/or platelet-specific alloantigens. Plasma (500-2000 mL) from each patient was passed over a protein A silica gel column and then returned to the patient. Patients received from 1 to 14 treatments. A positive response to protein A therapy was defined as at least a doubling of the pretreatment platelet count and/or two successive 10- to 120-minute posttransfusion CCIs > or = 7500. Following plasma treatments, 6 of 10 patients responded with daily platelet counts that averaged 48 +/− 11 × 10(9) per L as compared with counts of 16 +/− 7 × 10(9) per L (p < 0.0005) before treatment. Posttransfusion CCI values determined in four of these patients averaged 2480 +/− 810 and 10,010 +/− 3540 (p < 0.005) before and after treatment, respectively. In contrast, among the four unresponsive patients, platelet counts averaged 10 +/− 9 and 13 +/− 10 × 10(9) per L (p = NS), respectively, while posttransfusion CCIs were 700 +/− 1410 and 1520 +/− 2460 (p = NS), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
52.
University of Wisconsin solution is currently recognized as the best solution for long-term organ preservation. It is recommended that UW solution be used as the in situ flush prior to organ explantation. The purpose of our study was to determine if hepatic allograft function was impaired by flushing the graft in situ with Euro-Collins and later flushing the graft ex vivo with UW solution, prior to cold storage. Fifty-six donors were randomly assigned to either an EC (n = 24) or UW (n = 32) in situ flush. The livers flushed with EC in situ were later flushed with 1 L of UW on the back table and stored in UW solution. Livers flushed with UW in vivo were similarly flushed and stored in UW on the back table. Concerning the donor allograft, there was no statistical difference (P greater than 0.05) between groups in sex, race, blood type, arterial anatomy, age, prothrombin time (PT), partial thromboplastin time (PTT), total bilirubin (TBR), direct bilirubin (DBR), aspartate amino transferase (AST), or alanine amino transferase (ALT). In addition, the recipients were compared for differences in sex, race, blood type, preoperative status, number of rejections, recipient age, length of surgery, and ischemia time and patient survival. There was no significant difference between groups (P greater than 0.05). There was no significant difference in patient survival (P = 0.238). Values for TBR, AST, ALT, PT, PTT, and AP were collected immediately preoperatively and postoperatively and on postoperative days 1, 3, 7, 14, and 28. There was no difference between groups in these values (P greater than 0.05). In our study there was no difference between the groups with respect to graft performance. This would justify the use of EC as an in situ flush during solid organ procurement and flushing with UW solution on the back table with an estimated savings of $400 to $1200 per procurement.  相似文献   
53.
Background: Morbid obesity is a serious disease that afflicts over five million Americans, threatening their health with such co-morbidities as diabetes, arthritis, pulmonary failure and stroke. Surgery is the only effective therapy, providing long-term control of weight, diabetes, pulmonary failure, and hypertension for as long as 14 years. Because the operation presents a major expense, this study examined whether X-ray examination of the gut could be omitted safely as a cost-saving measure. Methods: The records of 814 consecutive morbidly obese patients who underwent gastric bypass were reviewed to determine: (1) whether these individuals had undergone an upper gastro-intestinal (GI) series, and (2) if these studies influenced therapy or caused cancellation or postponement of surgery. Results: Of the 814 patients, 657 (80.7%) underwent a preoperative GI radiography. Of these examinations, 393 (59.8%) were normal, with the following abnormalities in the remaining 264: hiatal hernia, 164; esophageal reflux, 39; Schatzki's ring, 18; small bowel diverticula, four; renal stones, four; malrotation, three; gall stones, two; pyloric ulcer, one; possible pelvic mass, one; calcified leiomyoma, one; and dysphagial lusoria, one. None of these findings resulted in cancellation or a delay in surgery. Conclusions: The upper GI series can be safely omitted from the routine preoperative evaluation of patients undergoing gastric bypass. At a cost of $741.00 per examination, this change represents significant potential savings. Similar evaluations of other routine preoperative tests may well provide a better basis for the evaluation of these complex patients.  相似文献   
54.
In 1987, die Department of Health in the UK set up a working party to identify reasons contributing to a shortfall in donor organs. One recommendation was reimbursement to the District Health Authorities for costs incurred in providing the donor organs. The figure chosen was not to be seen as an incentive to donate organs, merely as an appropriate compensation for the costs incurred. There would be no direct payment to doctors, trustees or relatives of the donor. With the development of the competitive health care environment in the United Kingdom, the reimbursement of donating hospital costs is being considered with these data.  相似文献   
55.
56.
STUDY OBJECTIVE--A chemical spill from an oil refinery exposed the local community to more than 40,000 lb of highly toxic and corrosive hydrofluoric acid. A community based symptom prevalence study found an association between exposure and physical symptoms: the psychological impact of the disaster and its potential effect on the reporting of physical symptoms is examined here. DESIGN--The study used a population based survey design consisting of two phases: phase I, the exposure phase, and, phase II, the symptom prevalence phase. SUBJECTS--In phase I, information indicative of exposure was collected on 10,811 individuals in a door to door survey of a geographically defined area. In phase II, symptom prevalence information was gathered through in-person interviews with 2509 subjects selected from the phase I census in a sampling scheme that balanced across the exposure categories with regard to age, gender, and predisposition. The refusal rate in both phases was < 5%. MEASUREMENT AND MAIN RESULTS--Stepwise logistic regression analyses were used to assess the relative predictive importance of psychological variables and hydrofluoric acid exposure in explaining the reported physical symptoms two years after the disaster. The findings show a linear relationship between the level of hydrofluoric acid exposure and the degree of psychological stress two years after the accident. High exposure had a long term (more than two years) impact on physical health for some self reported symptoms, even after controlling for the psychological impact. Some physical symptom reports, however, were better explained by psychological status than by exposure to hydrofluoric acid. The physical symptoms for which exposure was the major predictor were those for which the biological plausibility of a relationship with hydrofluoric acid exposure was direct. CONCLUSIONS--Measures of psychological status should be included in symptom studies of health sequelae to man-made disasters so that the physical effects of exposure can be more accurately assessed.  相似文献   
57.
58.
59.
60.
The role of open lung biopsy (OLB) in the diagnosis of the etiology of lung infiltrates in children was analyzed for a 10-year period 1979-1989 in a tertiary referral center. A total of 18 children had 19 lung biopsies to ascertain the cause of lung infiltrates. Thirteen of these children (72 %) were immunocompromised due to treatment of hematological/solid malignancies and bone marrow transplantation. The clinical diagnosis was bilateral lung infiltrates of unknown etiology in 17 of 18 children. Eight of these children were ventilated for respiratory failure. The biopsy was useful in achieving a histological diagnosis in 18 of 19 samples (diagnostic yield 95%) and an etiological diagnosis in 14 of 19 samples (etiological yield 74 %). Therapeutic strategy was altered in 14 of 18 patients based on the biopsy results. Five of 14 patients responded favorably to a change in specific treatment. The lime interval from onset of respiratory illness to biopsy was 2-60 days (mean 16 days). Despite the critical state of these children there were few complications associated with the biopsy and no mortality directly related to the procedure. We recommend that OLE be undertaken sooner rather than later in immunocompromised children with bilateral pulmonary infiltrates of unknown etiology.  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