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   38194篇
  免费   2682篇
  国内免费   33篇
耳鼻咽喉   320篇
儿科学   1002篇
妇产科学   830篇
基础医学   6074篇
口腔科学   731篇
临床医学   3959篇
内科学   8192篇
皮肤病学   781篇
神经病学   3357篇
特种医学   1386篇
外科学   5018篇
综合类   164篇
一般理论   21篇
预防医学   3132篇
眼科学   478篇
药学   2744篇
中国医学   66篇
肿瘤学   2654篇
  2023年   386篇
  2022年   138篇
  2021年   514篇
  2020年   564篇
  2019年   665篇
  2018年   1274篇
  2017年   1126篇
  2016年   1111篇
  2015年   977篇
  2014年   1052篇
  2013年   1912篇
  2012年   2861篇
  2011年   2965篇
  2010年   1308篇
  2009年   825篇
  2008年   2485篇
  2007年   2535篇
  2006年   2377篇
  2005年   2212篇
  2004年   2030篇
  2003年   1914篇
  2002年   1844篇
  2001年   969篇
  2000年   1085篇
  1999年   630篇
  1998年   177篇
  1997年   161篇
  1996年   119篇
  1995年   139篇
  1994年   130篇
  1993年   114篇
  1992年   155篇
  1991年   176篇
  1990年   162篇
  1989年   189篇
  1988年   180篇
  1987年   170篇
  1986年   151篇
  1985年   186篇
  1984年   191篇
  1983年   132篇
  1982年   122篇
  1981年   98篇
  1980年   83篇
  1979年   135篇
  1978年   94篇
  1977年   83篇
  1974年   69篇
  1933年   67篇
  1932年   70篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
The KID-syndrome in Finland. A report of four cases   总被引:2,自引:0,他引:2  
We describe a rare syndrome in a Finnish family, in which the father and his two sons are congenitally deaf and also exhibit corneal vascularization, and hyperkeratosis of the skin of the palms, soles, elbows and knees. In addition, all 3 suffer from fungal infections of the skin and nails. We also describe a fourth, sporadic case of a 9-year-old girl with the same disease. The KID (k = keratitis, i = ichthyosis, d = deafness) syndrome is an ectodermal dysplasia that probably arises through mutation, and is transmitted as an autosomal dominant in the family described by us.  相似文献   
33.
International comparisons show that populations having a high consumption of fish experience low incidence of breast cancer. We compared death rates from breast cancer among socioeconomic groups in a prospective study of 533,276 Norwegian women aged 35–54 years who were followed from 1970 through 1985. Compared with the reference group (wives of unskilled workers) the fishermen's wives had a decreased risk of breast cancer with a relative risk (RR) of 0.67 (95% confidence interval [CI]=0.47–0.94) adjusted for age and the number of children. Among fishermen's wives who were parous, adjustment for age at first birth gave an RR of 0.62 (CI=0.43–0.91). This study supports the hypothesis that certain aspects of diet, i. e., fish consumption, may be associated with lower breast-cancer mortality.Drs Lund and Bønaa are with the Institute of Community Medicine, University of Tromsø, Tromsø, Norway. Address correspondence to Dr Lund, Institute of Community Medicine, University of Tromsø, N-9037 Tromsø, Norway.  相似文献   
34.
The acute psychological reactions of 101 train drivers to on-the-track accidents were studied by means of clinical interviews and questionnaires (Impact of Event Scale, GHQ-20 and a questionnaire addressing stress symptoms, pre-accident expectancies and worries). More than half of the train drivers reported moderate to high intrusive distress (mean 11.3) within hours to days after the accident but only 1/3 reported symptoms of acute psychophysiological arousal. Intrusive symptoms related to visual impressions were most frequently reported. Avoidance was less prevalent (mean 8.8).

Clinical interviews, relationship between pre-accident worries and severity of the acute responses and positive correlation between GHQ-scores relating to the fortnight preceding the accident and IES-intrusion scores, suggest that premorbid variables may influence the stress response. Involvement in more than two previous accidents invoked a feeling of vulnerability and produced stronger acute responses. Post-accident experiences involving various personal contacts did not correlate with the stress responses in this study and only a few drivers experienced such events in a negative way. Denial of the possibility of being involved in accidents was not associated with increased risk of strong acute responses, indicating that denial does not predict poor outcome in healthy persons exposed to situations where possibility of avoiding the event is outside the control of the person.  相似文献   

35.
The purpose of this study was to determine whether patients who become carriers of methicillin-resistant Staphylococcus aureus (MRSA) during their stay in hospital, remain colonized after discharge. Thirty-six patients colonized with MRSA during one of three outbreaks at Utrecht University Hospital (1986-89) were screened 2 or 3 years after they had become carriers. Patients were also interviewed to determine factors contributing to persistent carriage, such as antibiotics, re-admissions to the hospital, presence of skin lesions and chronic diseases. At the same time transmission of MRSA to family members was determined. The epidemic MRSA strain was still found in three patients (8%). One was a cystic fibrosis patient who had had frequent re-admissions to the hospital and had received several course of antibiotic treatment. Both of the other patients had skin lesions: a fistula and a colostomy respectively. None of the 44 family members of the patients was colonized or infected with MRSA. We conclude that long-term MRSA carriage occurs with low frequency and is comparable to persistent carriage of methicillin-sensitive Staphylococcus aureus (MSSA). Transmission of MRSA to healthy individuals in an antibiotic-free environment is a rare event.  相似文献   
36.
37.
Reference data files support the evaluation of myocardial perfusion single-photon emission tomography (SPET). The aim of this study was to create a large reference data base for technetium-99m sestamibi SPET, age and gender matched to the general patient population. One hundred and twenty-eight healthy volunteers (76 males and 52 females) with a likelihood of coronary artery disease of less than 5% underwent rest and maximal exercise99mTc-sestamibi SPET with a 2-day protocol and 180° elliptical rotation. The normalized activity values of99mTc-sestamibi in the inferior wall differed significantly between men and women. Age variations were found for men in the anterior wall. Normalized activity values in all four walls were strikingly similar during rest and stress. Our results suggest that the use of reference files in99mTc-sestamibi SPET requires a gender- and, for males, possibly an age-matched reference population. Different reference files at rest and during stress might not be necessary.  相似文献   
38.
The effects of magnesium were compared with those of placebo in a randomized double-blind controlled study of 58 patients with pregnancy-induced hypertension, of whom 27 received magnesium and 31 placebo. Twenty patients in each group were nulliparas. The treatment comprised 48 h of either intravenous magnesium or placebo infusion followed by daily oral magnesium or placebo tablets until one day after delivery. Magnesium supplementation significantly reduced maternal mean arterial blood pressure (MAP). The gestational age at delivery was the same in both groups, whereas the relative fetal birth weight among nulliparas was reduced in the placebo group. Unbalanced analyses of variance suggested an influence of magnesium supplement on birth weight. The infants in the magnesium supplemented group spent fewer days in the neonatal intensive care unit. There were no perinatal deaths. Magnesium appeared to be beneficial in the management of pregnancy-induced hypertension. The better outcome associated with magnesium supplementation may not have been due to reduction of MAP and further studies are needed to clarify whether magnesium influences birth weight.  相似文献   
39.
The aim of this study was to evaluate the contribution of a low calcium diet to the cortical and trabecular osteoporosis seen in ovariectomized rats after 7 weeks on a low calcium diet and to investigate the effects of the bisphosphonate clodronate on this development of osteoporosis. Thirty-six mature, female Wistar rats were randomized into four groups: Ovx−B (bisphosphonate) and Ovx−C (control) were ovariectomized, and Sham−Ca (low calcium) and Sham+Ca (normal calcium) were sham operated. The first three groups were fed a low calcium diet (0.01%) and Sham+Ca normal rat chow (Ca 1.1%). The Ovx−B received 10 mg/kg s.c. clodronate daily for nine weeks, and Ovx−C, Sham−Ca, and Sham+Ca received the same volumes of saline. Bone mineral turnover measured as 85Sr-uptake was increased in all low calcium groups compared to Sham+Ca. The Sham+Ca femora had higher dry weight and ash weight than the other groups, and Ovx−C had higher dry weight compared with Ovx−B and Sham−Ca. Calcium content was lower in both Ovx groups compared to both Sham groups. Magnesium was lower in all groups compared to Sham+Ca and higher in Ovx−B compared with Ovx−C. In the femoral shaft, Sham+Ca had significantly higher ultimate bending moment, energy absorption, and deflection compared to the other three groups. Ultimate bending moment was higher in Sham−Ca than in Ovx−C. Stiffness was increased in both Sham+Ca and Ovx−B compared to Ovx−C. The maximum stress in the femoral midshaft was higher in Sham+Ca than in the other groups, and higher in Ovx−B than in Ovx−C. Histomorphometry showed increased medullary area in all low calcium groups compared to Sham+Ca and larger cortical area in Sham+Ca and Ovx−B compared to Ovx−C. Compared to Sham+Ca the trabecular bone volume was decreased to 30% in Sham−Ca and to 9% in Ovx−C, but was unchanged in Ovx−B. The low calcium diet generally increased bone mineral turnover and reduced the tibial bone volume. Femoral changes led to a reduction of cortical fracture strength and maximal stress. Ovariectomy in addition to a low calcium diet reduced femoral strength even more. Daily injections of clodronate to ovariectomized rats on a low calcium diet increased femoral shaft stiffness and maximum stress, and clodronate preserved both trabecular and cortical tibial bone volume completely. Received: 11 June 1996 / Accepted: 5 March 1997  相似文献   
40.
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