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   3170篇
  免费   280篇
  国内免费   14篇
耳鼻咽喉   14篇
儿科学   215篇
妇产科学   61篇
基础医学   320篇
口腔科学   89篇
临床医学   280篇
内科学   799篇
皮肤病学   40篇
神经病学   247篇
特种医学   222篇
外科学   471篇
综合类   152篇
预防医学   210篇
眼科学   48篇
药学   177篇
  1篇
中国医学   3篇
肿瘤学   115篇
  2021年   36篇
  2019年   36篇
  2018年   40篇
  2017年   33篇
  2016年   40篇
  2015年   47篇
  2014年   63篇
  2013年   84篇
  2012年   87篇
  2011年   94篇
  2010年   62篇
  2009年   91篇
  2008年   118篇
  2007年   125篇
  2006年   121篇
  2005年   100篇
  2004年   109篇
  2003年   99篇
  2002年   94篇
  2001年   88篇
  2000年   91篇
  1999年   90篇
  1998年   70篇
  1997年   68篇
  1996年   68篇
  1995年   59篇
  1994年   46篇
  1993年   53篇
  1992年   86篇
  1991年   103篇
  1990年   85篇
  1989年   82篇
  1988年   69篇
  1987年   65篇
  1986年   73篇
  1985年   73篇
  1984年   52篇
  1983年   52篇
  1982年   42篇
  1981年   39篇
  1980年   37篇
  1979年   46篇
  1978年   34篇
  1977年   28篇
  1976年   40篇
  1975年   36篇
  1974年   29篇
  1973年   42篇
  1972年   33篇
  1970年   29篇
排序方式: 共有3464条查询结果,搜索用时 15 毫秒
991.
BACKGROUND: Liver transplant recipients are at high risk for multi-drug resistant infections because of broad-spectrum antibiotic and immunosuppression. This study evaluates the clinical and financial impact of vancomycin resistant Enterococcus (VRE) in liver transplant recipients. METHODS: Liver transplant recipients with VRE from 1995 to 2002 were identified and matched (age, gender, UNOS status, liver disease and transplant date) to controls. Demographics, clinical factors, co-infections, antibiotic use, length of stay, abdominal surgeries, biliary complications, survival and resource utilization were compared with matched controls. RESULTS: Nineteen patients were found to have 28 VRE infections via evaluation of microbiologic culture results of all liver transplant patients in the transplant registry. Thirty-eight non-VRE patients served as matched controls. The four most common sites VRE was cultured from included blood (35%), peritoneal fluid (35%), bile (20%), and urine (12%). Median time from transplant to infection was 48 d (range of 4-348). No significant differences in demographics were observed. The VRE group had a higher incidence of prior antibiotic use than the non-VRE group (95% vs. 34%; p < 0.05). The VRE group also experienced more abdominal surgery (20/19 vs. 3/38; p = 0.029), biliary complications (9/19 vs. 9/38; p = 0.018) and a longer length of stay (42.5 vs. 21.7 d; p = .005). Survival in the VRE group was lower (52% vs. 82%; p = 0.048). Six of the 19 VRE patients were treated with linezolid for eight infection episodes, and four of six patients survived. Eight patients were treated with quinupristin/dalfopristin for nine infections, and two of eight survived. Increased cost of care was observed in the VRE group. Laboratory costs were higher in the VRE group (6500 dollars vs. 1750; p = 0.02) as well. CONCLUSION: VRE was associated with prior antibiotic use, multiple abdominal surgeries, biliary complications and resulted in decreased survival compared to non-VRE control patients. VRE patients also utilized more hospital resources. Linezolid showed a trend toward improved survival.  相似文献   
992.
BACKGROUND: Advising on ill-health retirement is an important role of most practising occupational physicians. In recent years, the eligibility criteria and process for gaining early retirement benefits have changed in many pension schemes in the UK. AIM: To investigate the variation in rates of retirement due to ill-health in National Health Service (NHS) Trusts and Local Authorities and to update previously published guidance on ill-health retirement with specific reference to pension schemes with eligibility criteria that include permanence of incapacity due to ill-health. METHODS: Rates of retirement were calculated for 222 NHS Trusts and 132 Local Authorities with more than 1500 employees. Literature searches and consensus statements by the authors. RESULTS: Rates of retirement were widely distributed in the NHS Trusts and Local Authorities. The median rates of retirement were 2.11 (IQR 1.37-2.91)/1000 active members and 4.10 (IQR 3.01-6.10)/1000 employees, respectively (P<0.001). Difficulties in the doctor-patient relationship and in ascertaining the true functional ability of some patients were identified. CONCLUSION: There continues to be marked variation in rates of early retirement due to ill-health within and between organizations that warrants further investigation. The general and specific guidance that appears as an appendix in Supplementary data to this paper should help occupational physicians to make equitable recommendations when assessing applications for early retirement benefits and fitness to work.  相似文献   
993.
994.
Pruss GJ  Lawrence CB  Bass T  Li QQ  Bowman LH  Vance V 《Virology》2004,320(1):107-120
Helper component-protease (HC-Pro) is a plant viral suppressor of RNA silencing, and transgenic tobacco expressing HC-Pro has increased susceptibility to a broad range of viral pathogens. Here we report that these plants also exhibit enhanced resistance to unrelated heterologous pathogens. Tobacco mosaic virus (TMV) infection of HC-Pro-expressing plants carrying the N resistance gene results in fewer and smaller lesions compared to controls without HC-Pro. The resistance to TMV is compromised but not eliminated by expression of nahG, which prevents accumulation of salicylic acid (SA), an important defense signaling molecule. HC-Pro-expressing plants are also more resistant to tomato black ring nepovirus (TBRV) and to the oomycete Peronospora tabacina. Enhanced TBRV resistance is SA-independent, whereas the response to P. tabacina is associated with early induction of markers characteristic of SA-dependent defense. Thus, a plant viral suppressor of RNA silencing enhances resistance to multiple pathogens via both SA-dependent and SA-independent mechanisms.  相似文献   
995.
996.
997.
Background: A clinical pathway for gastric bypass surgery (GBS) implemented at our institution in 1999 resulted in reduced costs and decreased variability in patient care. However, a reanalysis of GBS hospital costs identified a 16% incidence of"cost outliers".We hypothesized that analysis of clinical variables would identify factors associated with increased hospital costs following GBS. Methods: Medical records and financial data for 91 GBS patients from November 2000 to July 2001 were reviewed. Patients with costs >1 SD above the total hospital cost mean comprised the cost outlier (CO) group, while the remaining patients were considered the normal cost (NC) group. Potential etiologies for COs included patient demographics, the number and severity of medical co-morbidities, surgical factors, and major postoperative complications. Results: There were 15 patients in the CO group, and 76 patients in the NC group. Patient demographics were similar in both groups. Diabetes mellitus and severe medical co-morbidities, especially sleep apnea and degenerative joint disease were more common in the CO group (60% vs 9.2%, P<0.05 vs NC).The incidence of major complications (33% vs 8%) was significantly increased in the CO group (P<0.05 vs NC). Conclusions: Despite utilization of a clinical pathway for GBS, 16% of patients were "cost outliers". Factors associated with increased hospital costs after GBS included severe medical co-morbidities (especially diabetes mellitus and sleep apnea) and the occurrence of major postoperative complications. Prospective identification of "high risk" GBS patients may allow hospitals with bariatric surgery programs to modify perioperative care and eliminate potential cost outliers.  相似文献   
998.
999.
Premature very-low-birth-weight infants with posthemorrhagic hydrocephalus are often managed with intermittent cerebrospinal fluid drainage from a ventricular reservoir. There are little data regarding intracranial pressure changes during intermittent drainage to determine the amount and frequency of cerebrospinal fluid removal or to determine the correct resistance of future programmable shunts. The objective of this study was to determine the feasibility of using a commercially available intracranial pressure transducer to measure changes in pressure associated with this procedure. Continuous intracranial pressure was measured in three infants with a transducer placed at the time of ventricular reservoir insertion. Daily reservoir taps began 48 hours after placement and intracranial pressure was monitored for 7 days. Intracranial pressure before the initial tap was comparable to levels previously reported as normal. The daily removal of 10 cc/kg of cerebrospinal fluid was sufficient to lower intracranial pressure below baseline, however it was associated with wide swings in pressure and, in one patient, sustained negative pressure. The use of direct intracranial pressure monitoring may be useful in determining the optimal amount and frequency of cerebrospinal drainage from infants with posthemorrhagic hydrocephalus managed with a ventricular reservoir, as well as determining resistance settings of subsequent programmable shunts.  相似文献   
1000.
Our objective was to describe the sonographic appearance of the gluteus medius and minimus tendons in normal subjects, and to illustrate the spectrum of sonographic findings in gluteus tendinopathies. Sonography was performed in 20 asymptomatic volunteers. Seventy-five consecutive patients (59 women, 16 men; mean age 57.1 years) presented with pain and point tenderness over the greater trochanter. There were 43 right hips and 32 left hips. Ten patients provided a history of a traumatic incident with subsequent symptoms (mean duration 3.2 months). All patients underwent sonography to assess the site and severity of injury, and to discriminate tendinosis from partial and complete tear. Calcific foci, bony change, and fluid in the trochanteric bursae were noted. Twenty-two patients subsequently underwent surgery. Fifty-three (53 of 75) patients showed sonographic evidence of gluteus medius tendinopathy. Twenty-eight patients were thought to have tendinopathy without discrete tear. Sixteen patients had partial tears and 9 full-thickness tears. Gluteus minimus tendinopathy was detected in 10 of 75 patients. Foci of tendinopathy and partial tears were more common in the deep and anterior portions of the gluteus medius tendon attachment. Eight patients had fluid pooling in the trochanteric bursae. Findings were confirmed in 22 patients at surgery. Sonography can identify gluteus medius and minimus tendinopathy and provides information about the severity of the disease. Electronic Publication  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