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   754篇
  免费   49篇
  国内免费   1篇
耳鼻咽喉   3篇
儿科学   21篇
妇产科学   5篇
基础医学   59篇
口腔科学   9篇
临床医学   209篇
内科学   143篇
皮肤病学   4篇
神经病学   136篇
特种医学   27篇
外科学   39篇
综合类   12篇
一般理论   1篇
预防医学   67篇
眼科学   7篇
药学   34篇
肿瘤学   28篇
  2022年   5篇
  2021年   13篇
  2020年   6篇
  2019年   15篇
  2018年   17篇
  2017年   7篇
  2015年   10篇
  2014年   15篇
  2013年   24篇
  2012年   31篇
  2011年   42篇
  2010年   31篇
  2009年   14篇
  2008年   24篇
  2007年   31篇
  2006年   32篇
  2005年   31篇
  2004年   18篇
  2003年   33篇
  2002年   25篇
  2001年   9篇
  2000年   5篇
  1999年   7篇
  1998年   3篇
  1997年   6篇
  1996年   4篇
  1995年   6篇
  1992年   4篇
  1991年   7篇
  1990年   4篇
  1989年   6篇
  1988年   4篇
  1987年   6篇
  1986年   5篇
  1983年   18篇
  1982年   21篇
  1981年   18篇
  1980年   23篇
  1979年   21篇
  1978年   22篇
  1977年   29篇
  1976年   30篇
  1975年   25篇
  1974年   20篇
  1973年   18篇
  1972年   8篇
  1971年   7篇
  1970年   3篇
  1956年   3篇
  1954年   4篇
排序方式: 共有804条查询结果,搜索用时 46 毫秒
1.
The health status of many people in developing countries is often dismal compared with the norms in industrialized countries. Increasingly, medical practitioners in the United States and other industrialized countries have become interested in global health issues, an interest that often takes the form of short-term international medical trips. We discuss several ethical issues associated with participation in such trips and use our experiences in developing the Children's Health International Medical Project of Seattle (CHIMPS) to outline and illustrate a set of 7 guiding principles for making these trips. CHIMPS is a resident-run, faculty-supported international medical program founded in 2002 by pediatric residents at the University of Washington in Seattle. Members of CHIMPS work with a rural community in El Salvador to support ongoing public health interventions there and provide sustainable medical care in collaboration with the community and a local nongovernmental organization. The 7 principles developed as a result of this work-mission, collaboration, education, service, teamwork, sustainability, and evaluation-can be used as a model for health practitioners as they develop or select international medical trips. The importance of partnering with the community and working within the existing medical and public health infrastructure is emphasized. Many of the challenges of doing international medical work can be overcome when efforts are guided by a few specific principles, such as those we have outlined.  相似文献   
2.
OBJECTIVE: To evaluate the outcome of patients treated for appendiceal abscess, and managed either conservatively or surgically, and to describe the short and long-term outcome as well as incidence of interval appendicectomy in those treated conservatively. DESIGN: Retrospective study. SETTING: University hospital, Sweden. PATIENTS: Ninety-three patients with the diagnosis of appendiceal abscess, 50 treated conservatively and 43 who were operated on, with a mean age of 46 (14-93) years. Mean (range) follow-up for patients operated on was 65 (11-135) and for those treated conservatively 66 (6-136) months. MAIN OUTCOME MEASURES: Course of acute disease, recorded complications, recurrence of appendicitis and incidence of interval appendicectomy during follow-up. RESULTS: The duration of pain before admission was 4 (0.5-82) days for those operated on and 7 (2-60) days for those treated conservatively. A palpable mass was more common in the conservatively managed group. Complications were common among patients who were operated on. No interval appendicectomies were done during the second half of the study period. 4 of the patients treated conservatively (8%) had an underlying tumour diagnosed at follow-up. CONCLUSIONS: Operative management of patients with appendiceal masses seems to be associated with a high risk of postoperative complications and the risk of a more extensive surgical procedure. If possible, a conservative approach should be advocated. Because of inaccurate radiological imaging during the acute phase and the risk of an underlying malignancy, routine follow-up is necessary. Routine interval appendicectomy cannot be recommended.  相似文献   
3.
The aim of this study was to assess the expression of IGF-I and IGF-II in phyllodes tumours and fibroadenomas and to see if there is any correlation between nuclear beta-catenin expression and IGF-I and IGF-II expression in these tumours. In a previous study, it has been shown that Wnt signalling is important in the pathogenesis of phyllodes tumours of the breast. Epithelial Wnt5a overexpression and stromal Wnt2 overexpression were associated with abnormal, nuclear localization of beta-catenin in the stromal cells of these tumours. However, not all tumours with beta-catenin accumulation showed Wnt overexpression. One other possible cause of beta-catenin accumulation is overexpression of insulin-like growth factors (IGFs), as both IGF-I and IGF-II have been shown to stabilize beta-catenin. In this study, 30 fibroadenomas of the breast were assessed for beta-catenin expression using immunohistochemistry and the results were compared with previous data from 119 phyllodes tumours. In situ hybridization was used to assess IGF-I and IGF-II expression in 23 phyllodes tumours and 16 fibroadenomas. Nineteen phyllodes tumours (83%) showed widespread overexpression of IGF-II and 5/23 (22%) showed widespread overexpression of IGF-I. IGF-I expression correlated with nuclear beta-catenin staining in phyllodes tumours. Malignant phyllodes tumours showed no or little IGF-I expression. There was a degree of nuclear beta-catenin expression in the stroma (weak in 33%, moderate in 27%, and strong in 40%) in all fibroadenomas and nuclear beta-catenin staining correlated with IGF-I overexpression. Extensive IGF-II overexpression was also found in the majority of fibroadenomas (12/16). These results support the hypothesis that IGF-I and IGF-II overexpression may be important in the pathogenesis of fibroepithelial neoplasms of the breast and that IGF-I overexpression is likely to be contributing to the nuclear beta-catenin localization observed in the tumours.  相似文献   
4.
In a previous study of phyllodes tumours, it has been shown that both the stroma and the epithelium can exhibit distinct molecular changes, suggesting that both are part of the neoplastic process. In view of this finding, it was decided to study stromal-epithelial interactions in these tumours by examining the Wnt-APC-beta-catenin pathway. Beta-catenin and cyclin D1 immunohistochemistry was performed on 119 phyllodes tumours. Eighty-six (72%) showed stromal nuclear beta-catenin localization and in 57% the staining was moderate or strong; however, of the eight malignant tumours in the series, seven showed absent or weak nuclear staining (p<0.025). In no tumour was nuclear beta-catenin staining seen in the epithelial component. Moderate or strong stromal cyclin D1 staining correlated with nuclear stromal beta-catenin staining (p<0.05). Forty-five of the tumours, including two malignant lesions, were screened for beta-catenin exon 3 mutations using SSCP and sequencing, but none was found. Loss of heterozygosity (LOH) of the marker D5S346 was used to infer APC mutation, but only one (benign) tumour showed LOH. Wnt2 and Wnt5a mRNA was localized by in situ hybridization in 13 cases (three malignant) chosen to reflect the different beta-catenin staining patterns. There was an association between strong nuclear beta-catenin staining of stromal cells and epithelial Wnt5a expression (p<0.0015). These data suggest that stromal proliferation in benign phyllodes tumours relies on abnormalities in the Wnt pathway which result not from mutation, but from Wnt5a expression in the epithelium. In the progression to malignancy, the stromal proliferation appears to become independent of the Wnt pathway and, presumably, of the epithelial component of these tumours.  相似文献   
5.
We assessed the long-term efficacy of vagus nerve stimulation (VNS) in 64 refractory epilepsy patients. After implantation, intermittent stimulation was delivered and seizure frequency and severity were counted. Average treatment time was 20 months. Nineteen of 47 patients with partial seizures, five of nine patients with idiopathic generalized seizures, and five of eight patients with Lennox-Gastaut syndrome had >50% seizure reduction. Side effects were mild. VNS is a safe and effective treatment for refractory epilepsy.  相似文献   
6.
7.
8.

Background

The NHS Choices website (www.nhs.uk) provides data on the opening hours of general practices in England. If the data are accurate, they could be used to examine the benefits of extended hours.

Aim

To determine whether online data on the opening times of general practices in England are accurate regarding the number of hours in which GPs provide face-to-face consultations.

Design and setting

Cross-sectional comparison of data from NHS Choices and telephone survey data reported by general practice staff, for a nationally representative sample of 320 general practices (December 2013 to September 2014).

Method

GP face-to-face consultation times were collected by telephone for each sampled practice for each day of the week. NHS Choices data on surgery times were available online. Analysis was based on differences in the number of surgery hours (accounting for breaks) and the times of the first and last consultations of the day only between the two data sources.

Results

The NHS Choices data recorded 8.8 more hours per week than the survey data on average (40.1 versus 31.2; 95% confidence interval [CI] = 7.4 to 10.3). This was largely accounted for by differences in the recording of breaks between sessions. The data were more similar when only the first and last consultation times were considered (mean difference = 1.6 hours; 95% CI = 0.9 to 2.3).

Conclusion

NHS Choices data do not accurately measure the number of hours in which GPs provide face-to-face consultations. They better record the hours between the first and last consultations of the day.  相似文献   
9.
Malignant cells from four patients with acute promyelocytic leukaemia (APL) were analysed for coagulant and fibrinolytic activity. For comparison polymorphonuclear leucocytes from normal donors and myeloblasts from patients with acute myelogenous leukaemia (AML) were also tested. The APL cells compared to the other cells consistently shortened the recalcification time and partial thromboplastin time of normal, factor VIII deficient and factor IX deficient plasma, but had no effect on factor X deficient or factor VII-X deficient plasma. APL cells demonstrated increased (250–1500%) tissue factor activity when tested in a two-stage assay in which tissue factor is the rate limiting component. The increased tissue factor activity was primarily found in the granular fraction of APL cells. Fibrinolytic and proteolytic activity of the APL cells was variable. Cells from three of the APL patients demonstrated a slight increase (150–400%), while the cells from one APL patient had markedly diminished proteolytic activity. The increased fibrinolytic activity was associated primarily with the granular fraction. Although the fibrinolytic activity is increased, it does not parallel the increase in tissue factor activity. This imbalance of coagulation and fibrinolysis in the cellular composition of promyelocytes could explain the high incidence of clinical thrombo-haemorrhagic disorders related to intravascular coagulation in APL.  相似文献   
10.
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