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   5041篇
  免费   360篇
  国内免费   17篇
耳鼻咽喉   80篇
儿科学   190篇
妇产科学   113篇
基础医学   825篇
口腔科学   129篇
临床医学   390篇
内科学   1281篇
皮肤病学   130篇
神经病学   419篇
特种医学   122篇
外科学   691篇
综合类   15篇
一般理论   3篇
预防医学   271篇
眼科学   158篇
药学   284篇
中国医学   14篇
肿瘤学   303篇
  2023年   39篇
  2022年   65篇
  2021年   168篇
  2020年   91篇
  2019年   154篇
  2018年   163篇
  2017年   99篇
  2016年   111篇
  2015年   118篇
  2014年   165篇
  2013年   207篇
  2012年   343篇
  2011年   351篇
  2010年   190篇
  2009年   183篇
  2008年   284篇
  2007年   275篇
  2006年   272篇
  2005年   277篇
  2004年   262篇
  2003年   241篇
  2002年   212篇
  2001年   183篇
  2000年   196篇
  1999年   140篇
  1998年   57篇
  1997年   43篇
  1996年   41篇
  1995年   27篇
  1994年   24篇
  1993年   21篇
  1992年   66篇
  1991年   45篇
  1990年   41篇
  1989年   28篇
  1988年   25篇
  1987年   35篇
  1986年   14篇
  1985年   15篇
  1984年   17篇
  1983年   17篇
  1982年   11篇
  1979年   11篇
  1977年   9篇
  1976年   6篇
  1975年   9篇
  1973年   7篇
  1971年   7篇
  1970年   7篇
  1968年   6篇
排序方式: 共有5418条查询结果,搜索用时 328 毫秒
11.
In 20 post-operative patients who had undergone caesarean section, morphine 2 mg or fentanyl 75 micrograms in 0.9% saline were given epidurally in a randomized study, to compare their effectiveness in providing post-operative pain relief and the incidence of untoward reaction. There was a faster onset of action (P less than 0.01) and the quality of pain relief was substantially better after epidural fentanyl (P less than 0.01). However, the duration of action was markedly longer after epidural morphine (P less than 0.01). There was a significantly greater incidence of urinary retention after morphine administration (P less than 0.05). It is suggested that fentanyl gives better relief of pain than morphine when given epidurally.  相似文献   
12.
Little is known about oral health care behaviors of community-dwelling, cognitively impaired elderly (CIE) persons. Few studies have been conducted regarding the actual provision of oral care for CIE persons or the attitudes and concerns about oral health among their caregivers. The CIE person's ability to perform self-care decreases over time, and the role of the caregiver in daily oral care becomes increasingly important. The purpose of this pilot study was to explore the attitudes toward oral health and identify related concerns among caregivers who care for community-dwelling CIE persons. Caregivers were surveyed by means of a self-administered, mailed questionnaire. To maintain confidentiality, an intermediary was used for recruitment and data collection. Overall, 148 caregivers were invited by an intermediary to participate in the survey; only 21 (14%) consented to participate and returned the questionnaire. This paper discusses some of the numerous methodological challenges identified when an attempt was made to survey caregivers' attitudes toward and barriers to providing oral care for a dependent CIE.  相似文献   
13.
14.
The new diagnostic criteria of coeliac disease (CD) give more importance to serological markers. Immunoglobulin A antiendomysial antibodies (IgA-EmA) were determined in 138 sera from 79 coeliac children and the antibody levels compared to IgG and IgA antigliadin antibodies (IgG-AGA, IgA-AGA) in the sera. The assessment was also carried out in 29 children with other gastrointestinal diseases, 29 with non-gastrointestinal diseases and 35 healthy children. The IgA-EmA had a 91.4% specificity and a 88.4% sensitivity for active CD. The corresponding figures were 89.8% and 64.4% for IgA-AGA and 73.7% and 86.2% for IgG-AGA, respectively. The results of IgA-EmA determinations were concordant with the intestinal biopsy findings in 90% of cases, versus 80% for IgA-AGA and 83% for IgG-AGA. In most of the discordant cases the biopsy showed only minor changes, making the classification difficult. All patients with positive IgA2-EmA also had positive IgA1 EmA antibodies. IgA-EmA are an excellent serological marker of CD activity in children and they are useful to decrease the number of intestinal biopsies which are needed to confirm the diagnosis in coeliac patients.  相似文献   
15.
We report a case of a primary gastric Burkitt's lymphoma in a 8-year-old child, which first symptoms were abdominal pain, dysphagia, melena and a constitutional syndrome. The differential characteristics of this case are its peculiar gastric infiltration and the existence of oesophageal extension, which is very infrequent among this kind of tumors.  相似文献   
16.
Four children were diagnosed with idiopathic pulmonary hemosiderosis (IPH), over a period of 4 years. Retrospectively, antineutrophil cytoplasmic antibodies (ANCA) were studied by indirect immunofluorescence (IIF) and ELISA in 18 sera from these patients, stored at -20°C. ANCA-positive sera, from 1/20 to 1/1, 200 dilution, were found in 3/4 of the patients, by IIF. The patient with the highest titre of ANCA died 3 months later during an acute crisis, the other two patients need a minimal dose of steroids. In one case only, a patient who is still without treatment, had no ANCA. The antibodies anti-myeloperoxidase and anti-pro-teinase-3 were negative or at border line levels. Rheumatoid factor, anti-nuclear (Hep-2), anti-endomysial, anti-reticulin and antibasement membrane antibodies were negative in all sera. The surviving patients were followed-up for more than 10 years with no systemic or renal disease appearences. The presence of serum ANCA may help to classify children with pulmonary haemorrhage and may have a prognostic value.  相似文献   
17.
Gastric mucormycosis involvement is a rare condition that usually occurs in inmunocompromised patients and frequently has a fatal outcome. We report the case of a 73‐year‐old woman admitted to the intensive care unit with severe bleeding after an acute pulmonary disease. Upper endoscopy disclosed wide and deep necrotic ulcers in the body and fundus of the stomach and greenish exudates with the antrum and the duodenum undamaged. Autopsy revealed an invasive mucormycosis and a severe atheromatosis. Several predisposing factors for mucormycosis infection have been reported until now. We postulate that ischemic gastritis could be a predisposing factor for colonization of zygomycete.  相似文献   
18.
Summary We have studied the characteristics of arthritis present in 32 patients with Behçet's disease (BD), and how this arthritis is related to the HLA markers class I. 84% of the patients presented arthritis, the most common being monoarthritis as the initial presentation, and oligoarthritis in subsequent episodes. In 63% of the cases, the development was in episodes of acute/subacute arthritis. We found statistically significant association between antigens B-5 and B-51, and the group with BD, with a relative risk of 3.89 and 4.71 respectively. The attempt to relate markers B-5, B-51 and B-27 to the presence of arthritis as well as to its manifestation and further development was not conclusive.  相似文献   
19.
A 32-year old woman, with endocarditis caused by Streptococcus mitis, and systolic murmur is presented. The Doppler examination was found a systolic gradient of 150 mmHg. Aortography showed a multiple membranous supravalvular aortic stenosis, with aneurysmal dilatation of the left main coronary artery and circumflex artery, associated with bicuspid aortic valve and mild aortic insufficiency. The patient died suddenly by cardiac arrest in stand by to cardiac surgery. Anatomic comprobation was not possible. The coronary artery anomalies associated with the supravalvular aortic stenosis syndrome are reviewed.  相似文献   
20.
Tumour DNA ploidy as an independent prognostic factor in breast cancer   总被引:2,自引:0,他引:2  
We determined nuclear DNA content from 308 archival paraffin-embedded malignant breast tumours and evaluated the survival of the patients by univariate and multivariate statistical analyses. The overall 8-year survival rate of stage I-III breast cancer patients was 74.3% in DNA-diploid and 51.2% in DNA-aneuploid tumours (P less than 0.0001). DNA ploidy had prognostic significance in both node-negative and node-positive breast cancer, primarily in cases with steroid receptor-positive tumours. In a Cox multivariate analysis DNA ploidy (P = 0.001), primary tumour size (P = 0.0007), nodal status (P = 0.04) and the content of progesterone receptors (P = 0.0008) emerged as significant independent prognostic factors, whereas oestrogen receptor status, age and menopausal status of the patients had no significant independent prognostic value. If the histological grade of ductal carcinomas was also included in the Cox model, both grade and DNA ploidy had independent prognostic effect. In conclusion, our results indicate that the analysis of DNA ploidy is a useful adjunct in the assessment of prognosis for breast cancer patients.  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