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   1062篇
  免费   77篇
  国内免费   18篇
耳鼻咽喉   3篇
儿科学   81篇
妇产科学   8篇
基础医学   88篇
口腔科学   28篇
临床医学   75篇
内科学   191篇
皮肤病学   28篇
神经病学   23篇
特种医学   132篇
外科学   114篇
综合类   147篇
预防医学   74篇
眼科学   4篇
药学   58篇
中国医学   39篇
肿瘤学   64篇
  2023年   8篇
  2022年   17篇
  2021年   25篇
  2020年   20篇
  2019年   15篇
  2018年   21篇
  2017年   14篇
  2016年   19篇
  2015年   27篇
  2014年   42篇
  2013年   41篇
  2012年   48篇
  2011年   51篇
  2010年   73篇
  2009年   64篇
  2008年   28篇
  2007年   32篇
  2006年   40篇
  2005年   30篇
  2004年   18篇
  2003年   26篇
  2002年   13篇
  2001年   15篇
  2000年   10篇
  1999年   21篇
  1998年   45篇
  1997年   59篇
  1996年   51篇
  1995年   38篇
  1994年   32篇
  1993年   31篇
  1992年   9篇
  1991年   7篇
  1990年   10篇
  1989年   23篇
  1988年   19篇
  1987年   17篇
  1986年   16篇
  1985年   10篇
  1984年   10篇
  1983年   2篇
  1982年   9篇
  1981年   8篇
  1980年   11篇
  1979年   3篇
  1977年   6篇
  1976年   6篇
  1975年   2篇
  1958年   4篇
  1957年   2篇
排序方式: 共有1157条查询结果,搜索用时 0 毫秒
71.
Fourteen children receiving one year of recombinant human growth hormone (rhGH) treatment underwent measurement of serial changes in body composition (measured by skinfold thickness, bioelectrical impedance, and H2(18)O dilution), resting energy expenditure (REE, estimated by ventilated hood indirect calorimetry), and total free living daily energy expenditure (TEE, measured by the doubly labelled water technique). Mean height velocity increased from 4.9 to 8.6 cm/year after six months of treatment. Fat free mass (FFM) increased more during the first six weeks (24.4 g/day) than from six to 26 weeks of treatment (6.8 g/day); fat mass decreased by 7.2 g/day and 1.1 g/day respectively. The six week increase in REE (kJ/day) was maintained after six months of treatment, though expressed per kilogram FFM (kJ/kgFFM/day), returned to pretreatment values by three months. Height velocity increases at six months correlated with six week changes in fat mass measured by skinfold thickness and REE, though use of this relationship to predict growth response in individuals is limited by the wide 95% prediction intervals. No significant changes in growth, body composition, or energy expenditure were observed between six and 12 months of treatment, in either patients who had initially responded well to treatment or those who were poor initial responders to treatment and who had their dose of rhGH doubled after six months.  相似文献   
72.
73.
Recent reports have demonstrated that the HIV-1 transactivator protein,tat, induces apoptosis in T-lymphocyte cell lines, as well as in peripheral blood mononuclear cells, and stimulates a cascade of events resulting in up-regulation of the potent immunosuppressive cytokine, transforming growth factor-β (TGF-β). In this study we evaluated the ability of TGF-β to mediatetat induced apoptosis in T-lymphocyte cell lines. T-cells treated exogenously with either TGF-β1 or a combination of tat and pan-specific TGF-β neutralizing antibodies showed little change in the amount of apoptosis. When treated with pan-specific TGF-β neutralizing antibodies, Jurkat cells that stably expresstat protein (Jurkat-tat) showed only a modest decrease in apoptosis, while CEM-TART cells (CEM T-cells expressing both HIV-1tat andrev) demonstrated little change in the amount of apoptosis. In conclusion, we have demonstrated that TGF-β does not play a significant role in mediatingtat induced T-cell apoptosis.  相似文献   
74.
Commentary on acute renal failure in Asian region   总被引:1,自引:0,他引:1  
  相似文献   
75.
76.
BACKGROUND: Approximately 35% of patients acutely poisoned with organophosphates (OP) in developing countries like Sri Lanka require intensive care and mechanical ventilation. However, death rates remain high. OBJECTIVE: To study the outcomes and predictors of mortality in patients with acute OP poisoning requiring intensive therapy at a regional center in Sri Lanka over a period of 40 months. METHODS: Retrospective analysis of all intensive care records of patients with acute OP poisoning admitted to the Intensive Care Unit (ICU) between March 1998 and July 2001. RESULTS: During the study period, 126 subjects were admitted to the ICU with acute OP poisoning. Records of 10 patients were lost and those of 37 were incomplete and hence were excluded. All the remaining 71 patients (59 male) had required endotracheal intubation and mechanical ventilation for a period of four (median) days (range 1-27) in addition to gastric lavage and standard therapy with atropine and oximes and adequate hydration. Of these 71 patients, 36 (28 male) had died. Life table analysis demonstrated a steep decline in the cumulative survival to 67% during the first three days. Systolic blood pressure of < 100 mmHg and FiO2 of >40% to maintain a SpO2 of >92% within the first 24 h were recognized as poor prognostic indicators among mechanically ventilated patients. CONCLUSION: Mortality following OP poisoning remains high despite adequate respiratory support, intensive care, and specific therapy with atropine and oximes. One-third of the subjects needing mechanical ventilation and reaching intensive care units die within the first 72 h of poisoning. Systolic blood pressure of less than 100 mmHg and the necessity of a FiO2>40% to maintain adequate oxygenation are predictors of poor outcome in patients mechanically ventilated in the ICU.  相似文献   
77.
输血和大多数临床治疗技术一样,存在着一定的风险,输血风险主要由免疫性输血风险和输血感染性风险两大类相关的安全问题。20世纪80年代开始,由于艾滋病的发现迫使输血相关的安全问题更进一步成为公众关注的焦点。随着输血用血医学的不断发展,在已经获得很好治疗效果的同时,如何更加科学的安全用血是挑战当今公共卫生事业发展的一项大课题。  相似文献   
78.
Background--Currently, the reporting and archiving of echocardiographic data suffer from the difficulty of representing heart motion on printable 2-dimensional (2D) media. Methods and Results--We studied the capability of holography to integrate motion into 2D echocardiographic prints. Images of normal human hearts and of a variety of mitral valve function abnormalities (mitral valve prolapse, systolic anterior motion of the mitral leaflets, and obstruction of the mitral valve by a myxoma) were acquired digitally on standard echocardiographic machines. Images were processed into a data format suitable for holographic printing. Angularly multiplexed holograms were then printed on a prototype holographic "laser" printer, with integration of time in vertical parallax, so that heart motion became visible when the hologram was tilted up and down. The resulting holograms displayed the anatomy with the same resolution as the original acquisition and allowed detailed study of valve motion with side-by-side comparison of normal and abnormal findings. Comparison of standard echocardiographic measurements in original echo frames and corresponding hologram views showed an excellent correlation of both methods (P<0.0001, r2=0.979, mean bias=2.76 mm). In this feasibility study, both 2D and 3D holographic images were produced. The equipment needed to view these holograms consists of only a simple point-light source. Conclusions--Holographic representation of myocardial and valve motion from echocardiographic data is feasible and allows the printing on a 2D medium of the complete heart cycle. Combined with the recent development of online holographic printing, this novel technique has the potential to improve reporting, visualization, and archiving of echocardiographic imaging.  相似文献   
79.
The clinicopathological associations of 33 singleton infants who died with intraventricular haemorrhage (IVH) without hyaline membrane disease (HMD) ('IVH only') were compared with those of 39 infants who died with IVH+HMD over the same gestation range in order to determine what factors other than those related to HMD may contribute to the pathogenesis of IVH. The incidence of 'IVH only' was inversely related to gestational age in the Hammersmith birth population, whereas the incidence of IVH+HMD rose to a peak at 28-29 weeks' gestation. Infants with 'IVH only' lived longer on average than those with IVH+HMD despite a lower birthweight and shorter gestation. Infants who died in the first 12 hours from 'IVH only' had suffered severe birth asphyxia but in those who died later the main symptom was recurrent apnoea. Fewer infants with asphyxia but in those who died later the main symptom was.recurrent apnoea. Fewer infants with 'IVH only' were given alkali therapy or were connected to the ventilator as compared to those with IVH+HMD, but there were no differences in alkali therapy in those who lived for 12 hours or more. In the 'IVH only' group there was a high incidence of haemorrhage from other sites and of bacterial infections. It is suggested that, in the absence of HMD, extreme immaturity is the main factor determining the occurrence of IVH. Birth asphyxia, apnoeic attacks, haemorrhage, and infections may play subsidiary roles, possibly through development of metabolic acidosis.  相似文献   
80.
BACKGROUND: By 2016, the proportion of Canadians older than 65 years of age will increase to 16%, and there will be an increase in the absolute number of cases of cardiovascular disease in older Canadians. The Canadian Heart Health Surveys database provides information about this population upon which health policy related to cardiovascular disease can be based. This paper presents for the first time population-based data on the risk factors for cardiovascular disease in older Canadians. METHODS: Canadians from all 10 provinces participated in surveys of cardiovascular risk factors; health insurance registries were used as sampling frames. In each province, probability samples of 2200 adults 18 to 74 years old not living in institutions, on reserves or in military camps were asked to participate in interviews and to undergo testing at clinics for major risk factors for cardiovascular disease. RESULTS: A total of 2739 men (response rate 70%) and 2617 women (response rate 66%) aged 55 to 74 years participated in the survey and also provided follow-up clinical measurements at the clinic. Overall, 52% of participants were hypertensive, 26% had isolated systolic hypertension, and 30% had a total blood cholesterol level of 6.2 mmol/L or greater. Rates of current smoking were lower in women than men (17% v. 22%). Overall, 87% of men and 78% of women who were current smokers smoked at least 10 cigarettes per day. Only slightly more than half of participants exercised at least once a week for at least 15 minutes, and almost half had a body mass index of 27 or greater. In only 4% was no major risk factor for cardiovascular disease detected. INTERPRETATION: Significant numbers of older Canadians have one or more major risk factors for cardiovascular disease. Many of these risk factors are amenable to modification.  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