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   19333篇
  免费   1475篇
  国内免费   73篇
耳鼻咽喉   163篇
儿科学   626篇
妇产科学   534篇
基础医学   2909篇
口腔科学   286篇
临床医学   2208篇
内科学   3825篇
皮肤病学   591篇
神经病学   1939篇
特种医学   487篇
外科学   1852篇
综合类   159篇
一般理论   20篇
预防医学   2180篇
眼科学   338篇
药学   1163篇
中国医学   36篇
肿瘤学   1565篇
  2024年   41篇
  2023年   279篇
  2022年   504篇
  2021年   962篇
  2020年   586篇
  2019年   763篇
  2018年   824篇
  2017年   622篇
  2016年   705篇
  2015年   717篇
  2014年   879篇
  2013年   1132篇
  2012年   1643篇
  2011年   1676篇
  2010年   845篇
  2009年   742篇
  2008年   1149篇
  2007年   1162篇
  2006年   992篇
  2005年   962篇
  2004年   879篇
  2003年   782篇
  2002年   673篇
  2001年   106篇
  2000年   82篇
  1999年   102篇
  1998年   128篇
  1997年   110篇
  1996年   76篇
  1995年   80篇
  1994年   65篇
  1993年   48篇
  1992年   44篇
  1991年   52篇
  1990年   47篇
  1989年   26篇
  1988年   24篇
  1987年   28篇
  1986年   20篇
  1985年   31篇
  1984年   30篇
  1983年   26篇
  1982年   20篇
  1981年   30篇
  1980年   21篇
  1979年   11篇
  1978年   24篇
  1977年   11篇
  1976年   11篇
  1973年   11篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
The return of function following transection of the rat sciatic nerve has been assessed after repair by either standard microsurgical techniques (i.e., the use of microsutures to coapt the severed ends) or the new repair technique introduced by de Medinaceli and coworkers. The regeneration after transection was compared with that following sciatic nerve crush, i.e., a lesion in which the return of function is near optimal. Return of function was monitored serially using walking track analysis (i.e., the sciatic functional index, which indicates overall functional performance), the ability to spread the toes (which indicates intrinsic function in the foot), and the determination of muscle twitch tension of the middle digit. Function in the nerve crush group returned to within the normal range by 53 days, but function in the transection and repair groups did not return to normal before the rats were perfused at 85 postoperative days. However, the function regained when nerves were repaired with the de Medinaceli technique was significantly superior to that regained after repair with microsutures. Histological examination of the repair site (at 85 days) revealed that the regenerated nerve fibers in the de Medinaceli group crossed the site of anastomosis in a relatively orderly fashion, whereas they were more randomly arranged when microsutures were used. However, there was no statistical difference between the two groups in the number of regenerated fibers present in the distal stump. The increase in function in the de Medinaceli group may therefore arise primarily from an increase in the proportion of regenerating fibers which reach appropriate targets.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
42.
43.
Deep brain stimulation of the subthalamic nucleus (STN-DBS) is an established therapy for Parkinson's disease (PD). A manic episode with psychotic symptoms induced by STN-DBS occurred in a previously psychiatrically healthy patient, focusing on the role of STN-DBS in influencing not only motor but also emotional behaviour.  相似文献   
44.
From the data submitted to the Pan American Health Organization (PAHO) by nationwide programs against sexually transmitted diseases (STD), HIV infection, and AIDS (2002), one can estimate the overall prevalence of syphilis among pregnant women to be 3.1% and to range from 1.00% in Peru to 6.21% in Paraguay. According to these data, the incidence of congenital syphilis ranges from 1.4 per 1000 live births in El Salvador to 12.0 per 1000 live births in Honduras. Among men who engage in sex with other men, who often classify themselves as heterosexual, as well as in female sex workers, the prevalence of syphilis ranged from 5% to 15%. Factors that determine the persistence of congenital syphilis as public health problem include a lack of awareness of the seriousness of the problem among politicians, health officials, and health care providers, difficult access to prenatal care, and screening services, a low demand for the test among users, and the stigma and discrimination that surround sexually transmitted diseases (STD). This paper seeks to focus the attention of health professionals on maternal and congenital syphilis so they will undertake actions, using an interprogrammatic approach, to eliminate congenital syphilis from Latin America and the Caribbean. Eliminating congenital syphilis will only become possible if interventions targeting vulnerable groups are also implemented. PAHO's role in eliminating congenital syphilis includes determining the baseline situation in the Region as a whole and in each country, developing communication and procurement strategies, supporting nationwide programs, promoting operational research, and facilitating interprogrammatic coordination.  相似文献   
45.
OBJECTIVE: To investigate the opinions of stakeholders (service commissioners and providers) on how performance data should be presented, in order to develop effective feedback methods to facilitate the use of these data in decision making. DESIGN: A qualitative analysis of semi-structured face-to-face and telephone interviews. League tables and fictional box plots were presented as an illustrative guide. The themes covered in the interviews were the effectiveness of these two feedback formats, their positive and negative characteristics, and ideas for new and improved feedback mechanisms. PARTICIPANTS: Thirty-six stakeholders representing a range of clinical and non-clinical roles within palliative care and the wider health care system across a variety of statutory and non-statutory organizations from London and the West Midlands. RESULTS: Box plots were received more positively than league tables, and qualitative information was considered more appropriate than pictorial feedback. Conventional methods such as league tables and box plots were judged to lack essential information on which important decisions could be based, such as additional contextual information and the methodological assumptions of the instrument. Both feedback methods were considered useful as an impetus to further discussion. There was a consensus that feedback should be constructive and able to be adapted to the organizational realities in which UK health services function. CONCLUSION: Qualitative research was viewed as the right evidence for gaining an understanding of the quality of end of life care. Stakeholders highlighted the importance of the lay perspective, which requires approaches that illuminate the subjective meanings of patient experience.  相似文献   
46.
47.
The biliary excretion of radioactivity after intravenous [3H]25-hydroxyvitamin D3 was studied in nine patients with T-tube bile drainage. The mean +/- SD 24-hr radioactivity excretion in T-tube bile expressed as a percentage of the administered dose was 6.7 +/- 2.9%; after correction for incomplete bile collection, the value obtained was 16.0 +/- 11.1%. Chloroform solubility of biliary radioactivity increased from 27.4 +/- 8.9% to 72.9 +/- 10.1% following incubation with beta-glucuronidase. High-performance liquid chromatographic analysis of chloroform extracts of bile revealed that most of the eluted radioactivity was more polar than [3H]25-hydroxyvitamin D3. No free [3H]25-hydroxyvitamin D3 was demonstrated. Thus in man, most of the biliary radioactivity excreted following [3H]25-hydroxyvitamin D3 is in the form of water-soluble compounds, mainly glucuronides. However, our results suggest that glucuronides of metabolites other than 25-OHD3 are predominantly formed.  相似文献   
48.
49.

Background  

Persisting neck pain is common in society. It has been reported that the prevalence of neck pain in office workers is much higher than in the general population. The costs to the worker, employer and society associated with work-related neck pain are known to be considerable and are escalating. The factors that place office workers at greater risk of developing neck pain are not understood. The aim of this study is to investigate the incidence and risk factors of work-related neck pain in Australian office workers.  相似文献   
50.
Nitric oxide (NO) is a free radical produced by several lung cells via the enzyme nitric oxide synthetase (NOS) and can be easily measured in exhaled air by chemiluminescence analysis. As the iso-enzyme iNOS may be induced by cytokines and endotoxin, NO is elevated in several chronic inflammatory airway diseases. Prior to using exhaled nitric oxide (eNO) as a non-invasive marker of airway inflammation in daily routine, the role of possibly influencing factors such as age, time of the day, smoking exposure and intra-individual variability have to be clarified. NO concentrations were measured in 107 healthy children aged 4–18 years at an expiratory flow of 184 ml/s. Spirometry and a skin-prick test were performed and a questionnaire on family history of atopy, personal symptoms of atopic disease and smoke exposure was completed. For intra-individual variability nitric oxide was measured in six children three times daily on 6 consecutive days. Median eNO concentration was 5.7 p.p.b., and increased significantly with age but did not vary with gender. No correlation was found between eNO and smoke exposure, positive skin-prick test, FEV 1, MEF25 and time of the day. There was no circadian rhythm found in the six children measured on 6 consecutive days, but the eNO showed an intra-individual coefficient of variation of 25.9%. With the help of a two-compartment model of the lung the alveolar NO concentration was estimated to be 4.1 p.p.b and was shown to be constant with age, whereas the airway part of NO steadily increased with age. When comparing eNO values with standardized measurement techniques, the age of the children and the large intra-subject coefficient of variation have to be taken into account, whereas in healthy children subject-specific factors such as atopic history, gender and skin test reactivity did not affect eNO measurement.  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