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   3242篇
  免费   155篇
  国内免费   7篇
耳鼻咽喉   25篇
儿科学   76篇
妇产科学   63篇
基础医学   488篇
口腔科学   139篇
临床医学   263篇
内科学   675篇
皮肤病学   38篇
神经病学   333篇
特种医学   78篇
外科学   308篇
综合类   9篇
一般理论   1篇
预防医学   251篇
眼科学   121篇
药学   247篇
中国医学   23篇
肿瘤学   266篇
  2024年   3篇
  2023年   18篇
  2022年   45篇
  2021年   68篇
  2020年   56篇
  2019年   74篇
  2018年   86篇
  2017年   74篇
  2016年   82篇
  2015年   80篇
  2014年   122篇
  2013年   166篇
  2012年   259篇
  2011年   295篇
  2010年   153篇
  2009年   118篇
  2008年   201篇
  2007年   214篇
  2006年   225篇
  2005年   224篇
  2004年   211篇
  2003年   185篇
  2002年   160篇
  2001年   14篇
  2000年   21篇
  1999年   29篇
  1998年   23篇
  1997年   20篇
  1996年   15篇
  1995年   16篇
  1994年   17篇
  1993年   13篇
  1992年   13篇
  1991年   10篇
  1990年   15篇
  1989年   7篇
  1988年   7篇
  1987年   8篇
  1986年   9篇
  1985年   7篇
  1984年   8篇
  1983年   8篇
  1982年   3篇
  1981年   6篇
  1980年   2篇
  1979年   4篇
  1978年   3篇
  1977年   2篇
  1973年   1篇
  1966年   2篇
排序方式: 共有3404条查询结果,搜索用时 20 毫秒
61.

Objectives

Sarcopenia is a common geriatric syndrome, whose diagnosis implies the assessment of muscle mass. Dual-energy x-ray absorptiometry (DXA) is the reference method for clinical practice, but it is not universally available. We compared DXA with 2 anthropometry-based methods to assess muscle mass in older adults.

Design

Cross-sectional.

Setting

Ambulatory patients.

Participants

148 (87 female and 61 male) white older adults.

Measurements

Mid-arm muscle circumference (MAMC), whole skeletal muscle mass estimated by the Lee's formula (eTSMM), and relative skeletal muscle index (RSMI).

Results

Men and women did not differ for MAMC and RSMI, whereas eTSMM was higher (P < .001) in men. MAMC and eTSMM correlated with RSMI, in the whole sample as in men and women separately (P < .001). According to the McNemar test, the frequencies of older men and women with low muscle mass identified by eTSMM did not differ from those detected by RSMI (P = .066) at variance with MAMC. Using EWGSOP (European Working Group on Sarcopenia in Older People) criteria for RSMI as standard reference, the receiver operating characteristic (ROC) curves provided redefined cut-offs of reduced muscle mass: 18.6 cm in women and 22.3 cm in men for MAMC, and 17.7 kg in women and 28.3 kg in men for eTSMM. The areas under the ROC curves (AUCs) for MAMC were 0.882 in women (sensitivity 89%, specificity 84%) and 0.826 in men (sensitivity 94%, specificity 67%). The AUCs for eTSMM were 0.8913 in women (sensitivity 95%, specificity 81%) and 0.878 in men (sensitivity 97%, specificity 67%). No significant difference was found between the ROC curves of MAMC and eTSMM in both sexes.

Conclusion

Two simple anthropometric methods, possibly used in every clinical setting, could be valuable screening tools for low muscle mass in older subjects.  相似文献   
62.
The beneficial effects of beetroot juice supplementation (BJS) have been tested during cycling, walking, and running. The purpose of the present study was to investigate whether BJS can also improve performance in swimmers. Fourteen moderately trained male master swimmers were recruited and underwent two incremental swimming tests randomly assigned in a pool during which workload, oxygen uptake (VO2), carbon dioxide production (VCO2), pulmonary ventilation (VE), and aerobic energy cost (AEC) of swimming were measured. One was a control swimming test (CSW) and the other a swimming test after six days of BJS (0.5l/day organic beetroot juice containing about 5.5 mmol of NO3). Results show that workload at anaerobic threshold was significantly increased by BJS as compared to the CSW test (6.3 ± 1 and 6.7 ± 1.1 kg during the CSW and the BJS test respectively). Moreover, AEC was significantly reduced during the BJS test (1.9 ± 0.5 during the SW test vs. 1.7 ± 0.3 kcal·kg−1·h−1 during the BJS test). The other variables lacked a statistically significant effect with BJS. The present investigation provides evidence that BJS positively affects performance of swimmers as it reduces the AEC and increases the workload at anaerobic threshold.  相似文献   
63.
64.
65.
66.
67.
68.
69.
Abnormal adrenal function can interfere with linear growth, potentially causing either acceleration or impairment of growth in paediatric patients. These abnormalities can be caused by direct effects of adrenal hormones, particularly glucocorticoids and sex steroids, or be mediated by indirect mechanisms such as the disturbance of the growth hormone-insulin-like growth factor-1 axis and aromatization of androgens to oestrogens. The early diagnosis and optimal treatment of adrenal disorders can prevent or minimize growth disturbance and facilitate improved height gain. Mechanisms of growth disturbance in the following abnormal states will be discussed; hypercortisolaemia, hyperandrogenaemia and obesity. Prevalence and features of growth disturbance will be discussed in ACTH-dependent and ACTH-independent Cushing's syndrome, adrenocortical tumours, premature adrenarche, congenital adrenal hyperplasia and adrenal insufficiency disorders. Recommendations for management have been included.  相似文献   
70.

INTRODUCTION

Adenocarcinoma of the small intestine is a rare malignancy (the annual incidence in the USA is approximately 3.9 cases per million persons with median age between 60 and 70 years) with limited data available to guide therapeutic decisions. Nonspecific signs and symptoms associated with difficulty in performing small bowel examination is the cause of delayed diagnosis made between 6 and 9 months after appearance of symptoms with the majority of patients presenting with late stage disease and either lymph node involvement or distant metastatic disease.

PRESENTATION OF CASE

An 87-year-old man treated 3 years previously for colonic adenocarcinoma with left colectomy, was brought to our attention with a 4.5 cm × 3.5 cm mass in the proximal jejunum associated with another abdominal wall enhancing mass of 5 cm in diameter in the rectus muscle. Diagnosis on gross examination after surgical resection was adenocarcinoma stage III (T4N1M0) with involvement of lymph nodes.

DISCUSSION

According to an analysis of the Surveillance, Epidemiology and End Results (SEER) database, patients who develop either a small or large intestine adenocarcinoma are at increased risk for a second cancer at both intestinal sites. The role of adjuvant therapy in patients who undergo curative resection is unclear. Recent retrospective and prospective studies have helped to clarify the optimal chemotherapy approach for advanced small bowel adenocarcinoma.

CONCLUSION

With our work, we present our personal case of metachronous primary carcinoma of small bowel following resected colorectal carcinoma and review the literature.  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