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   2346022篇
  免费   175319篇
  国内免费   3315篇
耳鼻咽喉   32086篇
儿科学   75978篇
妇产科学   62752篇
基础医学   348413篇
口腔科学   63666篇
临床医学   211388篇
内科学   456409篇
皮肤病学   51748篇
神经病学   185450篇
特种医学   88067篇
外国民族医学   489篇
外科学   353805篇
综合类   47484篇
现状与发展   12篇
一般理论   851篇
预防医学   182604篇
眼科学   54410篇
药学   175199篇
  9篇
中国医学   4576篇
肿瘤学   129260篇
  2021年   19006篇
  2019年   19587篇
  2018年   27115篇
  2017年   20392篇
  2016年   22810篇
  2015年   25715篇
  2014年   36200篇
  2013年   54082篇
  2012年   74835篇
  2011年   79609篇
  2010年   47167篇
  2009年   44659篇
  2008年   74769篇
  2007年   79668篇
  2006年   80501篇
  2005年   77955篇
  2004年   74536篇
  2003年   71817篇
  2002年   69540篇
  2001年   108857篇
  2000年   111582篇
  1999年   93585篇
  1998年   27033篇
  1997年   23699篇
  1996年   24087篇
  1995年   22754篇
  1994年   20929篇
  1993年   19750篇
  1992年   72077篇
  1991年   70173篇
  1990年   68476篇
  1989年   65771篇
  1988年   60385篇
  1987年   59211篇
  1986年   55320篇
  1985年   53077篇
  1984年   39384篇
  1983年   33451篇
  1982年   19887篇
  1979年   35846篇
  1978年   25618篇
  1977年   21174篇
  1976年   20281篇
  1975年   21790篇
  1974年   26128篇
  1973年   24802篇
  1972年   23217篇
  1971年   22051篇
  1970年   20244篇
  1969年   19313篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
A cross-sectional, longitudinal study was undertaken on a group of acute non-A, non-B hepatitis patients, as well as on a control group of hepatitis B patients, in order to assess both the prevalence of the most important factors favoring infection, and the relevance of these factors in promoting evolution towards chronic liver disease. Exposures to unknown risk factors were present in 47.4% of acute non-A, non-B infections, followed by blood transfusions (17.9%), sporadic exposures (17.9%) and drug addiction (16.6%). Unknown as well as sporadic exposures showed a greater prevalence in control population if compared to non-A, non-B cases, while drug addiction was equally represented in the two groups, and blood transfusion nearly absent from control group. The risk of evolution to chronic liver disease was about 13 times greater in non-A, non-B group than in controls, with the greatest risk for drug addicts and the lowest for patients with unknown exposures. Among patients with known exposures, the lowest risk of chronic hepatitis was observed in post-transfusion and in sporadic cases, while the greatest was observed in drug addicts.Corresponding author.  相似文献   
992.
Summary Dock workers (n = 218) occupationally exposed to green coffee beans (GCB) were studied, using a specific questionnaire for allergic symptoms and skin tests for common and occupational allergens. Thirty-one workers (14.3%) complained of allergic symptoms of the eye, nose and bronchial system at the workplace. The prick tests, using both commercial allergens and specific extracts prepared from the most common types of coffee and their corresponding sacks, confirmed a sensitization in 21 workers (9.6%). A positive skin reaction to castor beans (CB) was found in nearly all these cases; in ten workers there was also a positive reaction to GCB allergens and in 14 cases prick tests were positive to extracts of sacks. There was a good concordance between prick tests and specific IgE for CB (95.0%) and also, but to a lesser extent, for GCB. The authors concluded that there is a significant risk of sensitization to CB and GCB allergens in dock workers occupied in handling green coffee bean, despite the fact that the exposure is not continuous. CB emerged as a common contaminant of GCB from various countries. For effective prevention, a modification of the methods of transport is required to avoid CB contamination to other products. Eliminating environmental dust during shipping operations is the most important preventive measure and it can be achieved by the use of containers, as some exporting countries are already doing.  相似文献   
993.
994.
The pilot study for a sentinel health events surveillance system for deaths among persons under age 45 with diabetes was conducted in six states in 1984 and 1985. Two hundred and thirty-three events were identified. Information from death certificates, physicians, and families revealed that 22% died from acute complications of diabetes and 53% from chronic complications. Blood pressure measurement and urinalysis testing had been performed in the last year for almost all of the decedents, but other preventive practices were reported less frequently. Hypertension was present in 57% and of those, was not controlled in 73%. Forty-four percent were cigarette smokers at the time of death. Agreement between physicians and families was generally higher for clinical conditions than for care practices. This surveillance system appears to yield information about the health care of persons with diabetes not readily available from other sources, although modifications may be necessary before implementation.  相似文献   
995.
996.
The sodium, potassium and creatinine contents of three non-consecutive 24-h urine samples collected by 34 selected adult individuals (10 m; 24 f) living in Cork City were determined. The pooled mean 24-h excretion of sodium and potassium in collections adjudged to be complete were 152 mmol and 78 mmol, respectively. There was no significant difference between group average weekday and weekend-day excretion of Na or K, for either males or females. This suggests that weekend 24-h urinary collections, which most subjects find more convenient, are suitable for studies of sodium and potassium intakes of groups. The ratios of intra- to inter-individual variation for 24-h urinary sodium were 1.4 and 2.1 for males and females, respectively. The corresponding ratios for 24-h urinary potassium were 6.6 for males and 4.9 for females. These ratios indicated that there were large individual day-to-day variations in urinary sodium and potassium excretion in this group. It was estimated that a sample size of 35-60 individuals would be required to estimate group mean sodium and potassium intakes by means of single 24-h urine collections.  相似文献   
997.
Internal eye wall resection in the management of uveal melanoma   总被引:3,自引:0,他引:3  
Twenty patients with presumed uveal melanoma underwent internal eye wall resection. It was the primary procedure in 13 patients who had tumours within 2 disc diameters of the optic nerve head and was combined with external resection in the remainder. Malignant melanoma was confirmed histologically in 15 patients; the diagnosis was a benign tumour in the other 5. The length of follow-up ranged from 2 to 37 (mean 19) months. In all cases the retina was completely attached at the time of last examination. The visual acuity ranged from 20/40 to hand movements; nine patients had an acuity of 20/400 or better. At the time of writing no metastatic disease or local recurrence had developed in any of the 15 patients in whom malignant melanoma was diagnosed.  相似文献   
998.
We examined six patients with Gardner's syndrome, eight first-degree relatives, and 31 age- and sex-matched controls to document the presence, distribution, and morphologic features of congenital hypertrophy of the retinal pigment epithelium. Patients with Gardner's syndrome had multiple, bilateral lesions, with 288 of 346 foci (83%) located posterior to the equator. Linear-shaped congenital hypertrophy of the retinal pigment epithelium, a distinctive finding in these patients, accounted for 44 of 140 large lesions (31%). Despite multifocal fundus involvement, results of electro-oculography were normal in all eyes tested.  相似文献   
999.
We evaluated the therapeutic efficacy of miconazole (MCZ, Florid-F inj.), a new antifungal agent for parenteral use, in deep-seated fungal infections of respiratory tract system. A daily dose of 400-1,800 mg of MCZ was given intravenously for 12-38 days (mean: 23.4 days) to 7 patients: 2 patients with pulmonary aspergillosis, 1 patient with bronchial aspergillosis, 1 patient with pulmonary candidiasis and 3 patients with candidemia. One additional patient with pulmonary aspergillosis received three instillations of 20 mg of MCZ into the thoracic cavity. The clinical effects were excellent in 1, good in 4 and poor in 3 patients. The efficacy rate was 100% in 5 cases with respiratory fungal infections but 3 cases with candidemia did not respond well to the treatment. Four strains each of Aspergillus sp. and Candida sp. were identified as causative organisms. Seven of the 8 strains were eradicated by administration of MCZ. Side effects observed were irritation and heat in a leg in 1 patient, hyperlipoidemia in 2 patients and eosinophilia in 1 patient. The adverse reactions disappeared after the completion of the therapy. From the above results, we conclude that MCZ is one of the most useful antifungal agents for parenteral use as a first choice on deep-seated fungal infections in the respiratory tract.  相似文献   
1000.
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