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   4658篇
  免费   346篇
  国内免费   63篇
耳鼻咽喉   46篇
儿科学   185篇
妇产科学   62篇
基础医学   683篇
口腔科学   62篇
临床医学   581篇
内科学   929篇
皮肤病学   117篇
神经病学   326篇
特种医学   371篇
外科学   526篇
综合类   49篇
一般理论   2篇
预防医学   475篇
眼科学   108篇
药学   263篇
中国医学   9篇
肿瘤学   273篇
  2023年   47篇
  2022年   66篇
  2021年   161篇
  2020年   109篇
  2019年   156篇
  2018年   163篇
  2017年   110篇
  2016年   108篇
  2015年   128篇
  2014年   190篇
  2013年   259篇
  2012年   338篇
  2011年   312篇
  2010年   182篇
  2009年   172篇
  2008年   197篇
  2007年   244篇
  2006年   184篇
  2005年   159篇
  2004年   139篇
  2003年   125篇
  2002年   127篇
  2001年   63篇
  2000年   78篇
  1999年   55篇
  1998年   99篇
  1997年   102篇
  1996年   115篇
  1995年   78篇
  1994年   70篇
  1993年   62篇
  1992年   48篇
  1991年   31篇
  1990年   31篇
  1989年   57篇
  1988年   62篇
  1987年   52篇
  1986年   58篇
  1985年   66篇
  1984年   21篇
  1983年   28篇
  1982年   23篇
  1981年   20篇
  1980年   13篇
  1979年   23篇
  1978年   17篇
  1977年   15篇
  1976年   21篇
  1975年   18篇
  1974年   13篇
排序方式: 共有5067条查询结果,搜索用时 15 毫秒
1.
2.
3.
We provide further evidence for the two-factor structure of the 9-item Academic Expectations Stress Inventory (AESI) using confirmatory factor analysis on a sample of 289 Canadian adolescents and 310 Singaporean adolescents. Examination of measurement invariance tests the assumption that the model underlying a set of scores is directly comparable across groups. This study also examined the cross-cultural validity of the AESI using multigroup confirmatory factor analysis across both the Canadian and Singaporean adolescent samples. The results suggested cross-cultural invariance of form, factor loadings, and factor variances and covariances of the AESI across both samples. Evidence of AESI's convergent and discriminant validity was also reported. Findings from t-tests revealed that Singaporean adolescents reported a significantly higher level of academic stress arising from self expectations, other expectations, and overall academic stress, compared to Canadian adolescents. Also, a larger cross-cultural effect was associated with academic stress arising from other expectations compared with academic stress arising from self expectations.  相似文献   
4.
BACKGROUND: Since 1997, a number of trials have shown promising results in treating generalized vitiligo with narrowband ultraviolet B (UVB) both in adults and children. However, there is little knowledge concerning the duration and permanency of the treatment-induced repigmentation. OBJECTIVE: Our main objective was to perform a follow-up trial of successfully treated patients receiving narrowband UVB for generalized vitiligo. METHODS: We have investigated to what degree the treatment-induced repigmentation remains stable for up to 2 years post-treatment. We performed an initial open trial including 31 patients with generalized vitiligo. They received narrowband UVB thrice weekly for up to 12 months. Patients experiencing > 75% repigmentation were defined responders and were included in the follow-up trial. Responders were followed every 6 months for up to 2 years after cessation of treatment. We observed the pigmentation status and registered any changes indicating loss of pigmentation and relapse. RESULTS: Eleven of the 31 treated patients were included in the follow-up trial. Six patients had relapse and five patients had stable response 24 months after cessation of treatment. Four out of six relapses were within 6 months post-treatment. CONCLUSION: In our study population of 31 patients with generalized vitiligo, five patients (16%) experienced > 75% stable repigmentation 2 years after cessation of a treatment programme of up to 1 years narrowband UVB therapy.  相似文献   
5.
Thirty-five patients hospitalized for recent angiographically documented arterial occlusion in the legs (27 femoropopliteal arteries and eight grafts) benefited from local fibrinolytic therapy delivered at the site of the occlusion with a 4- or 5-F catheter. This therapy combined a continuous urokinase (UK) infusion of 1,000 U/kg/hour and a lysyl plasminogen (LYS-PLG) infusion of 15 microkatals every 30 minutes. Angiographically confirmed lysis was obtained in 85% of the cases. Only 3% of the patients had major and 6% had minor groin hematomas. Only two patients had concentrations of fibrinogen as low as 100 mg/dl. Intravascular infusion of UK-LYS-PLG is as effective as streptokinase. Its excellent tolerance makes it a good alternative in the treatment of acute ischemia in the lower limbs.  相似文献   
6.
Median nerve somatosensory evoked potentials (SEPs) were monitored in patients with chronic pain before and after stellate ganglion blockade. A change caused by the syndrome or by the block would suggest that SEPs might be useful in the diagnosis and treatment of chronic pain. We observed 20 subjects. Group I (n = 10) had chronic pain not involving the upper extremity. Group II (n = 8) had reflex sympathetic dystrophy of the arm. All patients underwent unilateral stellate ganglion block using an anterior paratracheal approach. The SEPs were recorded by median nerve stimulation on the blocked (affected) side and unblocked (unaffected) side before and 30 min after the block. Recording sites were ipsilateral brachial plexus, the cervical spinal cord, and the contralateral sensory cortex. There were no between-group differences before or after the block. Paired analysis within each group showed that the SEPs were not different from baseline (unaffected side before block) at any time throughout the study. We conclude that since SEPs are not changed by the reflex sympathetic dystrophy or stellate ganglion block, they would not be useful in the evaluation of pain or in determining the effectiveness of sympathetic block. Both the pain and the block appear to involve alteration of conducting pathways separate from those monitored by median nerve SEPs.  相似文献   
7.
Birnholz  JC 《Radiology》1986,158(3):805-807
Ultrasound (US) can be used to visualize vertebral segments, suggesting a quantitative means of studying vertebral column growth in utero and thus a means of detecting developmental abnormalities. US images of the lumbar spine were obtained in 128 clinically normal fetuses between the gestational age of 11 through 41 weeks. A large-aperture, dynamically focused US system capable of regional magnification was used. Average lumbar spacing was calculated from distance between centrums of at least four lumbar bodies. The average distance between lumbar centrums increased nearly linearly throughout the second and third trimesters (r2 = 0.98). Enhanced anatomic display implies new capabilities for recognizing developmental abnormalities antenatally.  相似文献   
8.
9.
10.
A 54-year old man presented with multiple pulmonary emboli and an incidental finding of a huge left ventricular thrombus. Transthoracic echo images demonstrated a globally dilated heart with very poor left ventricular function. It was elected to manage the patient medically, and he was commenced on warfarin therapy, resulting in completed resolution of the thrombus over 10 weeks. No underlying cause was found and he did not experience any further embolic events. This illustrates a rare case of a large ventricular thrombus in a patient with no underlying risk factors.  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