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   18475篇
  免费   1443篇
  国内免费   71篇
耳鼻咽喉   185篇
儿科学   544篇
妇产科学   457篇
基础医学   2556篇
口腔科学   398篇
临床医学   1971篇
内科学   3827篇
皮肤病学   409篇
神经病学   1942篇
特种医学   556篇
外国民族医学   1篇
外科学   1983篇
综合类   132篇
一般理论   1篇
预防医学   1519篇
眼科学   503篇
药学   1093篇
中国医学   54篇
肿瘤学   1858篇
  2023年   165篇
  2022年   295篇
  2021年   632篇
  2020年   398篇
  2019年   630篇
  2018年   636篇
  2017年   483篇
  2016年   534篇
  2015年   580篇
  2014年   750篇
  2013年   996篇
  2012年   1369篇
  2011年   1410篇
  2010年   773篇
  2009年   637篇
  2008年   1094篇
  2007年   1121篇
  2006年   978篇
  2005年   885篇
  2004年   859篇
  2003年   774篇
  2002年   755篇
  2001年   241篇
  2000年   262篇
  1999年   244篇
  1998年   159篇
  1997年   123篇
  1996年   95篇
  1995年   93篇
  1994年   95篇
  1993年   93篇
  1992年   145篇
  1991年   162篇
  1990年   124篇
  1989年   144篇
  1988年   95篇
  1987年   109篇
  1986年   76篇
  1985年   79篇
  1984年   86篇
  1983年   49篇
  1982年   65篇
  1981年   69篇
  1980年   58篇
  1979年   65篇
  1978年   42篇
  1977年   47篇
  1976年   47篇
  1974年   39篇
  1971年   35篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Gangliocytic paragangliomas are rare tumors that almost exclusively occur within the second portion of the duodenum. Although these tumors generally have a benign clinical course, they have the potential to recur or metastasize to regional lymph nodes. The case report presented here describes a 57-year-old female patient with melena, progressive asthenia, anemia, and a mass in the second-third portion of the duodenum that was treated by local excision. The patient was diagnosed with a friable bleeding tumor. The histologic analysis showed that the tumor was a 4 cm gangliocytic paraganglioma without a malignant cell pattern. In the absence of local invasion or distant metastasis, endoscopic resection represents a feasible, curative therapy. Although endoscopic polypectomy is currently considered the treatment of choice, it is not recommended if the size of the tumor is > 3 cm and/or there is active or recent bleeding. Patients diagnosed with a gangliocytic paraganglioma should be closely followed-up for possible local recurrence.  相似文献   
2.
3.
4.
5.
6.
Background: Egyptian street youth use substances including tobacco, illicit drugs, and pharmaceutical drugs. To understand the circumstances, including adverse childhood experiences, that place adolescents at risk for engaging in substance use, we conducted in-depth interviews among a sample of Egyptian street children. Methods: From youth residing at or attending Caritas, a non-profit organization, which provides shelter and education to street youth, seven girls and twelve boys, aged 12–18 years, participated in open-ended, in-depth interviews. Results: Eight out of the 19 participants reported family history (early exposure) to substance use; and seven of them were initiated by either a family member (sibling), friend or coworker. Most of the participants reported a history of conflict with or abuse (verbal or physical) by their parents or siblings, or stressful situations at home; they used substance(s) to alleviate their stress. Few attended school, and some were forced to work and help their family. Conclusions: Among Egyptian youth, adverse childhood experiences, such as poverty, child abuse, and family substance use, challenge somewhat susceptible youths and lead them to the path of substance use and addiction. Prevention intervention should be multifaceted, culturally adaptable, and primarily targeting the social environment during childhood.  相似文献   
7.
8.
9.

Objectives

Short successive periods of skeletal muscle disuse have been suggested to substantially contribute to the observed loss of skeletal muscle mass over the life span. Hospitalization of older individuals due to acute illness, injury, or major surgery generally results in a mean hospital stay of 5 to 7 days, during which the level of physical activity is strongly reduced. We hypothesized that hospitalization following elective total hip arthroplasty is accompanied by substantial leg muscle atrophy in older men and women.

Design and participants

Twenty-six older patients (75 ± 1 years) undergoing elective total hip arthroplasty participated in this observational study.

Measurements

On hospital admission and on the day of discharge, computed tomographic (CT) scans were performed to assess muscle cross-sectional area (CSA) of both legs. During surgery and on the day of hospital discharge, a skeletal muscle biopsy was taken from the m. vastus lateralis of the operated leg to assess muscle fiber type–specific CSA.

Results

An average of 5.6 ± 0.3 days of hospitalization resulted in a significant decline in quadriceps (?3.4% ± 1.0%) and thigh muscle CSA (?4.2% ± 1.1%) in the nonoperated leg (P < .05). Edema resulted in a 10.3% ± 1.7% increase in leg CSA in the operated leg (P < .05). At hospital admission, muscle fiber CSA was smaller in the type II vs type I fibers (3326 ± 253 μm2 vs 4075 ± 279 μm2, respectively; P < .05). During hospitalization, type I and II muscle fiber CSA tended to increase, likely due to edema in the operated leg (P = .10).

Conclusions

Six days of hospitalization following elective total hip arthroplasty leads to substantial leg muscle atrophy in older patients. Effective intervention strategies are warranted to prevent the loss of muscle mass induced by short periods of muscle disuse during hospitalization.  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