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   4174篇
  免费   158篇
  国内免费   14篇
耳鼻咽喉   46篇
儿科学   64篇
妇产科学   65篇
基础医学   596篇
口腔科学   49篇
临床医学   488篇
内科学   803篇
皮肤病学   33篇
神经病学   390篇
特种医学   168篇
外科学   669篇
综合类   12篇
一般理论   1篇
预防医学   248篇
眼科学   37篇
药学   406篇
中国医学   13篇
肿瘤学   258篇
  2023年   13篇
  2022年   37篇
  2021年   111篇
  2020年   39篇
  2019年   73篇
  2018年   92篇
  2017年   60篇
  2016年   58篇
  2015年   81篇
  2014年   99篇
  2013年   161篇
  2012年   300篇
  2011年   284篇
  2010年   147篇
  2009年   143篇
  2008年   270篇
  2007年   275篇
  2006年   296篇
  2005年   285篇
  2004年   260篇
  2003年   232篇
  2002年   231篇
  2001年   42篇
  2000年   53篇
  1999年   30篇
  1998年   55篇
  1997年   43篇
  1996年   29篇
  1995年   37篇
  1994年   23篇
  1993年   25篇
  1992年   37篇
  1991年   26篇
  1990年   47篇
  1989年   34篇
  1988年   41篇
  1987年   35篇
  1986年   27篇
  1985年   42篇
  1984年   22篇
  1983年   18篇
  1982年   10篇
  1981年   8篇
  1979年   15篇
  1978年   10篇
  1977年   9篇
  1976年   7篇
  1974年   12篇
  1972年   10篇
  1970年   7篇
排序方式: 共有4346条查询结果,搜索用时 31 毫秒
11.
Coronary heart disease (CHD) is still relatively uncommon in the black population of South Africa. We embarked on a study to determine the prevalence of risk factors leading to CHD in the black population of Durban. The study sample was selected from patients attending a dental clinic at a hospital. A total of 458 patients (age range 16-69 years) was studied. The prevalence of CHD was 2.4%. The percentage prevalences of selected risk factors were: hypertension (blood pressure > or = 140 mmHg systolic and/or > or = 90 mmHg diastolic) 28% (31.9% for males, 25.4% for females); protective levels of high-density lipoprotein/total cholesterol > or = 20%, 81.3%; diabetes mellitus 4.9% for males, 2.9% for females; smoking > or = 10 cigarettes per day 28.1% for males, 3.4% for females; obesity 3.7% for males 22.6% for females. We found the Minnesota Coding System for electrocardiographic changes of CHD and the Rose questionnaire to be unreliable for eliciting CHD in blacks. Hypercholesterolaemia is less common, and this may explain the low incidence of CHD in blacks. Epidemics of CHD as seen in Indian, coloured and white South Africans can still be prevented in the black population, but preventive measures must be instituted rapidly.  相似文献   
12.
Twenty-four hour urinary free cortisol and mean and integrated 13h00-16h00 plasma cortisol levels were measured in 9 patients with proven Cushing's syndrome (5 with Cushing's disease, 2 with ectopic adrenocorticotrophic hormone production due to bronchial carcinoma and 2 with adrenal adenomas) and in 21 patients without Cushing's syndrome. The 24-hour urinary free cortisol levels and mean and integrated 13h00-16h00 plasma cortisol estimations clearly distinguished patients with Cushing's syndrome from those without. However, adequate suppression on dexamethasone suppression tests (false negatives) were obtained in 3 of the 9 patients with Cushing's syndrome. Since the integrated 13h00-16h00 plasma cortisol estimation is cheaper and simpler than the mean 13h00-16h00 plasma cortisol estimation, we recommend it as an adjunct in the diagnosis of Cushing's syndrome.  相似文献   
13.
Bartonella henselae, previously called Rochalimaea henselae, is the causative agent of cat scratch disease (CSD) in immunocompetent subjects and bacillary angiomatosis in immunocompromised ones. Bone lesions are common in bacillary angiomatosis, but not in CSD. We present the case of a patient with a renal transplant treated by immunosuppressive therapy who developed a sternal abscess with a histological pattern of CSD. The CT pattern was that of a lytic bone lesion with adjacent fluid collection. The diagnosis was made on the basis of a polymerase chain reaction amplification performed on bone material. Bartonella henselae is a newly described bacteria that causes CSD in a normal host and bacillary angiomatosis in immunocompromised patients. We report a case of an osteolytic lesion of the sternum with adjacent fluid collection related to CSD, which occurred in a patient with a renal transplant.  相似文献   
14.
Non-invasive ambulatory recordings of blood pressure and heart rate were performed using a Spacelabs device during day and night periods in patients with Parkinson's disease with (n = 19) or without orthostatic hypotension (n = 19). In patients with orthostatic hypotension, the average systolic and diastolic blood pressure during the night (137 ± 5/80 ± 3 mmHg) was higher (p < 0.05) than during the day period (121 ± 3/76 ± 2 mmHg). In patients without orthostatic hypotension, a decrease in blood pressure was recorded during the nocturnal period. In patients with orthostatic hypotension, the blood pressure variability was higher (p < 0.05) during the day (systolic: 14.6 ± 1.3%; diastolic: 16.5 ± 1.0%) than during the night (systolic: 9.1 ± 0.8%; diastolic: 10.8 ± 1.1%). The blood pressure load (percentage of values above 140/90 mmHg) during the night was significantly higher than during the day for both systolic (41.2 ± 8.1 vs. 19.6 ± 4.7%) and diastolic blood pressure (24.9 ± 6.9 vs. 16.3 ± 4.9%). There was a decrease in heart rate in both groups during the night. A fall of 25 mmHg or more in systolic blood pressure after meals occurred in ten patients with orthostatic hypotension and in one patient without orthostatic hypotension. These results indicate that orthostatic hypotension in Parkinson's disease is associated with specific modifications of ambulatory blood pressure including loss of circadian rhythm of blood pressure, increased diurnal blood pressure variability and post-prandial hypotension.  相似文献   
15.
Huntington chorea is rare in ethnically pure blacks; 8 South African black patients, 6 adults and 2 children, from 4 families are described. The symptoms do not appear to differ materially from Huntington chorea in other races. Increased awareness of the disease in this population group is warranted.  相似文献   
16.
BACKGROUND: Genetic factors other than HLA have been reported to be associated with the outcome of organ transplantations. Because binding of FasL to its receptor Fas could play an important role in tubulitis and in the death of graft tubular epithelial cells during kidney allograft rejection, a gene polymorphism recently identified in position -671 in the promoter of the TNFRSF6 gene coding for Fas was investigated in donors. METHODS: A case-control study was performed within a cohort of non-hyperimmunized adult patients who had received cadaveric kidney transplants based on the occurrence or absence of acute cellular rejection in the first 6 months after renal transplantation. Each recipient from the acute rejection group (n = 35) was matched for age (+/- 5 years) and number of HLA-DR mismatches with two recipients within the non-acute rejection group (n = 70). RESULTS: The TNFRSF6-GG genotype was more frequent in donors in the group without rejection episodes. In contrast, patients who received a kidney from a TNFRSF6-A carrier were more likely to experience acute rejection episodes (relative risk nearly 2.1). CONCLUSION: This study suggests that donor TNFRSF6 polymorphism directly or indirectly influences acute kidney rejection episodes.  相似文献   
17.
The acute muscarinic and nicotinic side-effects of organophosphate poisoning are well known. Less commonly encountered are neurological symptoms such as chorea and psychiatric disturbances such as psychoses and depression. Two patients with organophosphate poisoning are described, both exhibiting marked choreiform dyskinesias and one experiencing severe depression and emotional lability. Both responded well to the appropriate treatment. Because of the widespread use of organophosphate insecticides in agriculture, the neurological and psychiatric effects of chronic low-dose exposure to organophosphates in farmers and their employees deserves attention.  相似文献   
18.
A cross-sectional study of 976 coloured subjects aged 15-64 years identified a population consuming a typical Western diet. Nutrient intake, determined by the 24-hour dietary recall method, reflected a diet high in fat (37% of total energy intake) and animal protein and a polyunsaturated/saturated fatty acid ratio of 0.85. Only 32.2% of men and 27.5% of women consumed a prudent diet (Keys score less than or equal to 28). The influence of this Western diet on serum total cholesterol (TC) levels was seen to be marked when participants with a high risk of developing coronary heart disease (CHD) were compared with those with a TC level putting them at low risk; the former consumed significantly more saturated fat and had a higher mean Keys score. Multiple linear regression analysis on TC levels of men identified six variables that explained 26.9% of the variation of TC. These were body mass index, age, the inverse of the polyunsaturated fat intake, saturated fat intake, polyunsaturated/saturated fat ratio and cholesterol intake. For women only three variables (age, the inverse of the polyunsaturated/saturated fat ratio, and body mass index) explained 30.2% of the variation of TC. Promotion of the prudent diet to lower TC levels of the coloured population of the Cape Peninsula is an increasingly urgent priority.  相似文献   
19.
Students (N = 377) from four Cape Town township high schools were surveyed to obtain information on their knowledge of and attitudes towards the acquired immunodeficiency syndrome (AIDS), and on their sexual behaviour. The study was undertaken to provide information for planning an AIDS education intervention. Three-quarters of students reported that they had had sexual intercourse. Most students had heard of AIDS, and the majority of these knew that it was infectious. More than half of the students were confused or lacked knowledge about the modes of transmission. Two-thirds of the students believed AIDS could be prevented, but knowledge of prevention strategies was superficial. Of the sexually active students only 11.4% had ever used a condom, and of all students 39.6% stated that they would use a condom in the future. Two-thirds of the students were not aware that there is no cure for AIDS. Students did not acknowledge that AIDS could affect them directly, and attributed the problem to prostitutes and 'promiscuous' people in 36.4% of responses, and to 'white' people in 23.8% of responses. Students expressed intolerance, fear and rejection of people with AIDS, and only 6.4% would accept an affected person into their class. Almost all the students wanted AIDS education at school, and most of these requested that the school nurse facilitate this education. It is concluded that appropriate AIDS prevention education is urgently required for both high school and junior school students.  相似文献   
20.
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