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   147174篇
  免费   11073篇
  国内免费   3537篇
耳鼻咽喉   864篇
儿科学   3790篇
妇产科学   1535篇
基础医学   9611篇
口腔科学   1450篇
临床医学   21271篇
内科学   36232篇
皮肤病学   769篇
神经病学   4372篇
特种医学   3247篇
外国民族医学   8篇
外科学   14409篇
综合类   26156篇
现状与发展   11篇
一般理论   4篇
预防医学   11407篇
眼科学   572篇
药学   13784篇
  203篇
中国医学   8951篇
肿瘤学   3138篇
  2024年   396篇
  2023年   2456篇
  2022年   4377篇
  2021年   6182篇
  2020年   6223篇
  2019年   5243篇
  2018年   5352篇
  2017年   5026篇
  2016年   5250篇
  2015年   5165篇
  2014年   11027篇
  2013年   11152篇
  2012年   9225篇
  2011年   9779篇
  2010年   7629篇
  2009年   7008篇
  2008年   6738篇
  2007年   6848篇
  2006年   5991篇
  2005年   5429篇
  2004年   4363篇
  2003年   3860篇
  2002年   3156篇
  2001年   2887篇
  2000年   2333篇
  1999年   2182篇
  1998年   1809篇
  1997年   1696篇
  1996年   1456篇
  1995年   1389篇
  1994年   1355篇
  1993年   978篇
  1992年   899篇
  1991年   836篇
  1990年   706篇
  1989年   657篇
  1988年   579篇
  1987年   502篇
  1986年   442篇
  1985年   560篇
  1984年   486篇
  1983年   299篇
  1982年   352篇
  1981年   289篇
  1980年   262篇
  1979年   194篇
  1978年   187篇
  1977年   145篇
  1976年   132篇
  1975年   82篇
排序方式: 共有10000条查询结果,搜索用时 18 毫秒
991.
Today some authors consider univentricular repair a contraindication for postoperative cardiac extracorporeal membrane oxygenation (ECMO). The question is whether or not ECMO is indicated as pulmonary support in case of an overwhelming pulmonary infection during the postoperative course after a Norwood procedure. During the prolonged weaning period after a Norwood procedure using a 4 mm aortopulmonary shunt, proven respiratory syncytial virus (RSV) bronchiolitis occurred at the time of expected weaning from artificial ventilation. Venovenous ECMO was able to improve oxygenation, but when pulmonary opacification failed to resolve, ECMO was terminated after 12 days.  相似文献   
992.
Rheumatic heart disease is a significant clinical entity in young children, especially in the developing world. One of the major long-term effects of ill managed rheumatic fever is irreversible damage to the cardiac valve leaflets, primarily on the left side. With the limited success of currently available mechanical and bioprosthetic valves, there is an urgent need for new directions in bioprosthetic valves, both in material, including source, degree of fixation, surface, bulk modifications, etc., and design. In the present paper, new proposals in the material selection and fabrication of bioprosthetic valves are proposed based on electron microscopic studies of natural valve leaflets and the pericardial surface. Current approaches for bioprosthetic valve fabrications include the wide use of the pericardium as a leaflet material. The present study indicates a need for nondestructive surface examination of pericardial sheets for the elimination of areas of surface voids resulting from gross fiber disorientation. Also, there seems to be a need for incorporation of an in situ fiber renewal mechanism in bioprosthetic leaflets to emulate the natural valve more closely. Apparently natural leaflets have built-in fiber renewal mechanism(s).  相似文献   
993.
In severely burned patients the approach to the central vein is often difficult due to concomitant edema, but also due to the fact that the skin area, where commonly used approaches are performed, is burned as well, whereas the axillary region is often not involved. In order to perform an axillary approach to the central vein as an alternative to the commonly used approaches in patients, an anatomical dissection in fresh human cadavers was carried out. Considering the anatomical landmarks which were found during dissection of the axillary region, the axillary approach to the central vein was used in 35 patients in our intensive burn care unit with unaffected axillary skin. In three cases the only complication observed was an occasional puncture of the axillary artery without major hematoma. The infection rate of the catheters was similar to the commonly used puncture sites. This approach to the central venous line in severely burned patients can be recommended.  相似文献   
994.
江苏省肾综合征出血热监测与疫情预测指标研究   总被引:7,自引:1,他引:6       下载免费PDF全文
目的 探讨直接利用肾综合征出血热(HFRS) 定点监测资料对全省疫情进行定性预测的意义,寻找敏感且易获得的预测指标。方法 兼顾不同地理状况,选点开展鼠密度、鼠带毒率、带毒鼠指数、健康人群抗体水平监测;对江苏省1986 年以来12 年的有关监测资料与人间疫情进行相关性分析。结果 春季室内褐家鼠(Rn) 密度,混合鼠种及Rn 带毒率、带毒鼠指数与春峰疫情有显著性相关关系;秋季野外混合鼠种及黑线姬鼠(Aa) 密度、带毒鼠指数与秋冬峰疫情显著性相关;全年平均鼠密度、鼠带毒率、带毒鼠指数与全年疫情显著性相关;人群隐性感染率与人间疫情无明显相关关系。其中,春季室内混合鼠种及褐家鼠带毒鼠指数与春峰疫情间相关系数分别为0 .8637、0 .8295 ( P< 0.001) ;秋季野外混合鼠种、黑线姬鼠带毒鼠指数与秋冬峰疫情间相关系数分别为0 .7089 、0 .7258 (P< 0 .01),与次年春峰疫情间相关系数分别为0.7118、0 .7113 ( P< 0.01) ;全年平均带毒鼠指数与全年疫情间相关系数为0.9207 ( P< 0 .001)。结论 带毒鼠指数为定性预测出血热疫情的首选指标;在布夹数均衡性较好条件下,鼠密度可作为预测的辅助指  相似文献   
995.
Differing pathological haemodynamics in cardiac malformations lead to varying modes and timings of presentation. This study identifies historical trends in presentation of congenital heart disease in a population-based study. All patients diagnosed as having congenital heart disease in Malta between 1960–1994 were included (n = 868). Analysis was carried out on trends in referral sources, modes of presentation and birth prevalence. The number of patients diagnosed with congenital heart disease increased over the period under study. For both patients not requiring intervention (n = 283) and those requiring intervention (n=585), the proportion diagnosed prior to hospital discharge increased (p 0.005). There was a decreasing trend for general practitioners to refer cases (p < 0.0001), and an increasing trend for paediatricians to refer such patients (p 0.0003). The commonest presentation to the general practitioner was an incidental finding (92%), while paediatricians referred more patients for cyanosis or heart failure (p 0.005). For lesions not requiring intervention, the commonest lesion referred was ventricular septal defect from all sources. For lesions requiring intervention, the commonest lesion detected prior to hospital discharge was tetralogy of Fallot. Atrial septal defects were the commonest lesions detected after discharge by both paediatricians and general practitioners. An increase in the proportion of hospital diagnoses is attributed to increasing rate of hospital delivery, and greater training and experience in doctors performing neonatal examinations prior to discharge. Patients diagnosed after discharge are increasingly diagnosed by paediatricians due to an increasing pool of paediatricians and better parent awareness and education.  相似文献   
996.
Cancer mortality was analysed in 3282 elderly subjects aged 65 years from 2 cohorts of general population having different life-style patterns. They took part in the CASTEL (CArdiovascular STudy in the ELderly), a 12-year lasting prospective Italian study. The aim of the present analysis was to identify the items able to influence cancer mortality. A biochemical profile and a questionnaire on lifestyle were collected. Continuous items were averaged and compared with analysis of variance, frequencies with the Pearson's 2 test. Mortality was recorded yearly for 12 years from the Registrar's Office and causes of death double-checked by consulting medical case sheets and family doctors' files. The influence of items on mortality was evaluated with the Cox multivariate analysis. Relative risk (RR) of each item was adjusted for confounders. Age, gender, tobacco smoking, the presence of respiratory symptoms, low body mass index in males, serum alanine transaminase (ALT) and alkaline phosphatase (ALP), as well as the town of residence, were powerful predictors of cancer mortality. In the entire population, 12-year overall mortality was 49.4%, cardiovascular 22.8%, and neoplastic 11%; the latter was higher in males than in females (15.7% vs. 7.9%, p < 0.00001). In subjects with respiratory symptoms neoplastic mortality was 11.6% (RR: 1.47) vs. 9.7% in those without symptoms (p < 0.01). Subjects with very low cholesterol ( 178 mg/dl), those with high uric acid ( 8.7 mg/dl) and males with low body mass index ( 22.7 kg/m2) has an increased risk of cancer mortality. RR of cancer mortality increased with increasing ALT or ALP. It was 1 in those having ALT and ALP between 9 and 41.2U/I, 1.41 in those exceeding this latter level and < 1 in those below 9U/I. RR of ALP had a similar trend, the best protective cut-off value being <106 and the worst one > 177U/I. When both serum enzymes were simultaneously raised, RR of cancer mortality increased to 2.84.  相似文献   
997.
We performed this case–control study to evaluate the risk of hypoglycemia associated with the use of antihypertensive drugs in older hospitalized diabetic patients treated with sulfonylureas and/or insulin. All diabetic patients admitted during 4 months in 1988, 1 month in 1991, 4 months in 1993 and 4 months in 1995 (n = 3477, mean age 71.4 ± 0.2 years, 1542 males and 1935 females) were enrolled in the study. During the four annual surveys 86 patients (mean age 71.1 ± 1.4 years, 33 males and 53 females) presented hypoglycemia during hospital stay. The patients who presented hypoglycemia were less frequently users of sulfonylureas and more frequently users of a combination of insulin and sulfonylureas. Use of antihypertensive drugs was similar in the two groups studied, and among potentially interacting drugs considered in the analysis, sulfonamides were more frequently used in patients who experienced hypoglycemia. Moreover, patients with hypoglycemia used a higher number of drugs, had a longer length of stay and had a greater prevalence of hypoglycemia as admission problem. Finally, although not significant, liver and renal diseases were more frequent among patients with hypoglycemia. In the multivariate analysis, contemporary use of insulin and sulfonylureas, liver disease and length of stay were significantly associated with hypoglycemia, while none of the antihypertensive drugs showed a significant association with the occurrence of hypoglycemia during hospital stay. Our results indicate that antihypertensive drugs do not increase the risk of hypoglycemia in elderly diabetic patients.  相似文献   
998.
999.
Objective: The specific objectives of this study were to: 1) study the effect of moderate-to-severe asthma on patient's Health-Related Quality of Life (HRQoL) as measured by the Medical Outcomes Study 36-item Short-Form Health Survey (SF-36) and 2) evaluate the construct validity of a modified and shortened version of the Living With Asthma Questionnaire (ms-LWAQ) using the SF-36 as a concomitant measure of HRQoL. Methods: Cross-sectional, telephone or mail surveys of asthmatic patients enrolled in two central Florida managed care organizations. Results: All subscales of the SF-36 and four subscales of the ms-LWAQ demonstrated adequate reliability in this population (Cronbach >0.72). The subscales of the SF-36 most affected by patient's asthma were: general health perceptions, vitality and physical role functioning. These three subscales were correlated with four subscales of the ms-LWAQ: consequences, seriousness, affect and leisure. Six of the eight SF-36 subscales and all of the ms-LWAQ subscales were associated with patient's emergency department and hospital utilization. Conclusion: The ms-LWAQ and SF-36 are valid as useful measures of asthma patient's HRQoL in this cross-sectional study. Severity of disease, as measured by health care utilization, was significantly associated with HRQoL.  相似文献   
1000.
There are increasing numbers of children with a disability living in the community who require enteral tube feeds to optimize their nutritional status. Whilst there appears to be evidence of health gains, for some children there may also be serious and unintended social deprivations resulting from the need to be tube fed. This paper reviews the literature on support for children who are tube fed and makes a case for more coordinated and effective support services for families who are tube feeding a child at home. It is argued that national guidance should be developed which clarifies the position of all non-parent carers and staff who are willing to administer enteral tube feeds. Such guidance should also ensure that enterally-fed children have the same rights to educational and social services as other children and that families are given the opportunity to make informed decisions about the implications of enteral feeding prior to it being established.  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