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   930524篇
  免费   67497篇
  国内免费   1340篇
耳鼻咽喉   12957篇
儿科学   24358篇
妇产科学   23232篇
基础医学   132874篇
口腔科学   28241篇
临床医学   80525篇
内科学   183217篇
皮肤病学   19226篇
神经病学   72168篇
特种医学   36797篇
外国民族医学   79篇
外科学   152061篇
综合类   18042篇
现状与发展   1篇
一般理论   234篇
预防医学   61735篇
眼科学   21307篇
药学   72520篇
  3篇
中国医学   2162篇
肿瘤学   57622篇
  2018年   8959篇
  2017年   7025篇
  2016年   7758篇
  2015年   8856篇
  2014年   11980篇
  2013年   17491篇
  2012年   24074篇
  2011年   25025篇
  2010年   14797篇
  2009年   14261篇
  2008年   24591篇
  2007年   25680篇
  2006年   26471篇
  2005年   25417篇
  2004年   24550篇
  2003年   23595篇
  2002年   23141篇
  2001年   54724篇
  2000年   56541篇
  1999年   46947篇
  1998年   10730篇
  1997年   9464篇
  1996年   9592篇
  1995年   8926篇
  1994年   8278篇
  1993年   7593篇
  1992年   35487篇
  1991年   33911篇
  1990年   32734篇
  1989年   31869篇
  1988年   28991篇
  1987年   28249篇
  1986年   26288篇
  1985年   25144篇
  1984年   17832篇
  1983年   15141篇
  1982年   7795篇
  1981年   6771篇
  1979年   15781篇
  1978年   10598篇
  1977年   9052篇
  1976年   7871篇
  1975年   8628篇
  1974年   10466篇
  1973年   9858篇
  1972年   9357篇
  1971年   8852篇
  1970年   8426篇
  1969年   7923篇
  1968年   7200篇
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
991.
992.
BackgroundSeveral studies have shown that socioeconomic deprivation is associated with increased hospitalization lengths of stay (LOS) and costs. Yet, the French DRG-based information system (PMSI) does not take deprived situations into account. Hence, we aimed at extracting routinely available variables measuring deprivation from the Hospital Information System and at assessing their association with severity of illness and hospital LOS.MethodsWe performed record linkage between the PMSI database concerning stays of patients aged more than 16 years in the short-stay sector of Assistance publique–Hôpitaux de Paris in 2007 and an administrative database which provided the following deprivation measures: recipients of Couverture Médicale Universelle (basic or complementary health insurances adapted for underprivileged French citizens) or Aide Médicale d’État (health and medical emergency insurances adapted for underprivileged non French citizens living in France) and homeless patients. We compared length of stays showing a deprivation measure to others after adjustment on morbidity, age and sex.ResultsAmong 352,721 stays, the prevalence of the deprivation measures ranged from 0.71% for “homelessness” to 6.24% for complementary Couverture Médicale Universelle. Stays showing a deprivation measure had specific illnesses and had more frequently associated comorbidities or complications than others. After adjustment, deprivation measures were associated with significantly increased LOS (by 5% for Couverture Médicale Universelle to 48% for emergency Aide Médicale d’État.ConclusionRoutine extraction of deprivation measures from Hospital Information Systems is feasible. Age, sex and illness being equal, these deprivation measures were associated with more complicated cases and increased LOS. We recommend that case mix-based hospital prospective payment systems take socioeconomic deprivation into account.  相似文献   
993.
The intervertebral disc is characterized by a tension-resisting annulus fibrosus, and a compression-resisting nucleus pulposus composed largely of proteoglycan. Both the annulus and the nucleus function in concert to provide the disc with mechanical stability. Early disc degeneration begins in the nucleus with proteoglycan depletion. Quantitative MRI techniques have been developed to non-invasively quantify the earliest degenerative changes that occur within the disc. Our ability to identify and quantify these early biochemical changes will provide a better understanding of the pathophysiology of disc degeneration and facilitate the study of interventions that aim to halt or reverse the degenerative process.  相似文献   
994.
995.
996.
OBJECTIVE: To quantify the dietary calcium and vitamin D intake in adult renal-transplant recipients attending at a large teaching hospital in Ireland for follow-up. SETTING: Outpatient renal-transplant follow-up clinic. SUBJECTS: Fifty-nine adult renal transplant recipients (58% male) with a mean age of 46 years, a median transplant duration of 6 years, and a mean estimated glomerular filtration rate (eGFR) of 50 mL/min per 1.73 m2. Fifty-three percent were at National Kidney Foundation stage 3 chronic kidney disease, and 14% had stage 4 chronic kidney disease. INTERVENTION: This cross-sectional, observational study used a tailored food frequency questionnaire specific for calcium and vitamin D intake in Irish adults, which was completed during a face-to-face interview with each subject. MAIN OUTCOME MEASURE: The main outcome measure was the average daily dietary and supplemented calcium and vitamin D intake. RESULTS: The median interquartile range (IQR) dietary calcium intake was 820 mg/day (range, 576-1,177 mg/day), and was similar in men and women (recommended intake > or = 1,000 mg/day in adult men and nonmenopausal adult women, > or = 1,500 mg/day in menopausal women). Five participants received calcium supplementation. Overall, 59% of men and 64% of women had total calcium intakes below the recommended amounts. The median IQR estimated dietary vitamin D intake was 5.2 microg/day (range, 2.4-6.4 microg/day) in women, and 4.6 microg/day (range, 2.2-6.6 microg/day) in men (recommended intake, > or = 10 microg/day). Six subjects received vitamin D supplementation. Total vitamin D intakes were suboptimal in 91% of men and 87% of women. Dietary calcium and vitamin D intakes significantly correlated with each other, but neither was significantly related to eGFR category, and was similarly low in both presumed menopausal women and in the initial year posttransplantation. CONCLUSION: These findings suggest that dietary and total calcium and vitamin D intakes in adult renal-transplant patients are in many cases inadequate.  相似文献   
997.
For chronic thromboembolic pulmonary hypertension not amenable to pulmonary endarterectomy, effective medical therapy is desired. In an open-label uncontrolled clinical trial, 104 patients (mean +/- sem age 62 +/- 11 yrs) with inoperable chronic thromboembolic pulmonary hypertension were treated with 50 mg sildenafil t.i.d. At baseline, patients had severe pulmonary hypertension (pulmonary vascular resistance 863 +/- 38 dyn.s.cm(-5)) and a 6-min walking distance of 310 +/- 11 m. Eight patients were in World Health Organization functional class II, 76 in class III and 20 in class IV. After 3 months' treatment, there was significant haemodynamic improvement, with reduction of pulmonary vascular resistance to 759 +/- 62 dyn.s.cm(-5). The 6-min walking distance increased significantly to 361 +/- 15 m after 3 months' treatment, and to 366 +/- 18 m after 12 months' treatment. A subset of 67 patients received a single dose of 50 mg sildenafil during initial right heart catheterisation. The acute haemodynamic effect of this was not predictive of long-term outcome. In this large series of patients with inoperable chronic thromboembolic pulmonary hypertension, open-label treatment with sildenafil led to significant long-term functional improvement. The acute effect of sildenafil may not predict the long-term outcome of therapy.  相似文献   
998.
Objective  Stiffness and severe deformity pose a major challenge in total knee arthroplasty. Numerous techniques have been described to gain exposure and improve knee flexion. Tibial tubercle osteotomy provides excellent and safe exposure of the joint, although mechanical and wound complications have been reported. Materials and methods  We present a series of 32 consecutive complex primary total replacements where an osteotomy of the tibial tubercle was utilised. Results  The patients had a mean follow-up of 2 years and 11 months. Following the procedure, with the exception of one case complicated with deep infection, all of the patients had improved clinically. The mean postoperative range of motion had increased to 102° (give P value < 0.005) and there were no cases of delayed union or non-union. A mechanical complication related to technique occurred in one patient; there were no other cases with a postoperative extension lag. Conclusion  In this challenging population group, we have found a tibial tubercle tuberosity osteotomy to greatly facilitate exposure without compromising the clinical and radiographic outcome.  相似文献   
999.
1000.
A METHOD FOR CONTINUOUS SPINAL ANESTHESIA: A PRELIMINARY REPORT   总被引:1,自引:1,他引:0  
Lemmon WT 《Annals of surgery》1940,111(1):141-144
  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