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   25245篇
  免费   1283篇
  国内免费   78篇
耳鼻咽喉   333篇
儿科学   1426篇
妇产科学   622篇
基础医学   2821篇
口腔科学   571篇
临床医学   1465篇
内科学   5339篇
皮肤病学   776篇
神经病学   1574篇
特种医学   790篇
外科学   3254篇
综合类   767篇
一般理论   15篇
预防医学   1256篇
眼科学   1408篇
药学   2273篇
  1篇
中国医学   182篇
肿瘤学   1733篇
  2023年   180篇
  2022年   447篇
  2021年   916篇
  2020年   446篇
  2019年   573篇
  2018年   743篇
  2017年   519篇
  2016年   638篇
  2015年   589篇
  2014年   949篇
  2013年   1150篇
  2012年   1627篇
  2011年   1772篇
  2010年   937篇
  2009年   779篇
  2008年   1216篇
  2007年   1247篇
  2006年   1243篇
  2005年   1069篇
  2004年   972篇
  2003年   831篇
  2002年   752篇
  2001年   702篇
  2000年   703篇
  1999年   561篇
  1998年   229篇
  1997年   164篇
  1996年   142篇
  1995年   150篇
  1994年   115篇
  1993年   99篇
  1992年   367篇
  1991年   370篇
  1990年   338篇
  1989年   328篇
  1988年   284篇
  1987年   251篇
  1986年   234篇
  1985年   232篇
  1984年   171篇
  1983年   135篇
  1981年   91篇
  1979年   157篇
  1978年   97篇
  1977年   81篇
  1975年   83篇
  1974年   100篇
  1973年   92篇
  1972年   118篇
  1970年   78篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
INTRODUCTION: Radiofrequency (RF) tissue ablation has been tried safely and effectively in the West as percutaneous local tissue ablation therapy. We present our experience with this technique in malignant lesions. METHODS: RF tumor ablation was done using an RF generator (Berchtold; Germany) generating 35-50 RF watts of power output. The RF needle was placed in the tumor under image guidance (n = 22) or at open surgery (n = 1). Around 1500 watts/cm3 RF energy was delivered to the tumor. Over 21 months, 23 patients underwent the procedure for 73 lesions, including metastatic liver lesions (n = 21) and locally advanced inoperable carcinoma of pancreas (n = 2). RESULTS: All lesions less than 3 cm in size (n = 15) and 39% of lesions 3-4 cm in size (17/44) had complete necrosis. Residual tumor was seen in 27/44 lesions (61%) 3-4 cm in size and in all 14 lesions more than 4 cm in size. There was no mortality or major morbidity. There were two minor complications (ascites 1, pleural effusion 1). Of 21 patients treated for liver metastases, 10 are still alive (6-month survival 19/21 [90%] and 12-month survival 11/17 [64.7%]). Only 2 of 32 (6.2%) lesions with complete necrosis had local recurrence. CONCLUSION: RF tumor ablation is a safe and effective local tissue ablative method in Indian patients.  相似文献   
53.
OBJECTIVES: The purpose of this study was to determine quality of life (QOL) and exercise performance (EP) in patients with persistent atrial fibrillation (AF) converted to sinus rhythm (SR) compared with those remaining in or reverting to AF. BACKGROUND: Restoration of SR in patients with AF improving QOL and EP remains controversial. METHODS: Patients with persistent AF were randomized double-blind to amiodarone, sotalol, or placebo. Those not achieving SR at day 28 were cardioverted and classified into SR or AF groups at 8 weeks (n = 624) and 1 year (n = 556). The QOL (SF-36), symptom checklist (SCL), specific activity scale (SAS), AF severity scale (AFSS), and EP were assessed. RESULTS: Favorable changes were seen in SR patients at 8 weeks in physical functioning (p < 0.001), physical role limitations (p = 0.03), general health (p = 0.002), and vitality (p < 0.001), and at 1 year in general health (p = 0.007) and social functioning (p = 0.02). Changes in the scores for SCL severity (p = 0.01), functional capacity (p = 0.003), and AFSS symptom burden (p < 0.001) at 8 weeks and in SCL severity (p < 0.01) and AF symptom burden (p < 0.001) at 1 year showed significant improvements in SR versus AF. Symptomatic patients were more likely to have improvement. The EP in SR versus AF was greater from baseline to 8 weeks (p = 0.01) and to 1 year (p = 0.02). The EP correlated with physical functioning and functional capacity except in the AF group at 1 year. CONCLUSIONS: In patients with persistent AF, restoration and maintenance of SR was associated with improvements in QOL measures and EP. There was a strong correlation between QOL measures and EP.  相似文献   
54.
55.
Introduction Myxopapillary ependymomas are low grade tumours that are known to recur locally even after complete excision, but metastasis to distant sites is extremely uncommon. Case report We report an unusual case of lumbo-sacral myxopapillary ependymoma in a 13-year-old boy with metastasis to both cerebellopontine angles. To the best of our knowledge, this is the youngest patient of metastatic myxopapillary ependymoma.  相似文献   
56.

Background  

Many factors impacting cecal intubation rates have been examined in detail; however, little information exists regarding the effect of the timing of the procedure. We sought to examine any difference in cecal intubation rates between morning and afternoon colonoscopies and identify factors contributing to a discrepancy.  相似文献   
57.
58.
The infant is the youngest but perhaps the most valuable member of society. It has been unequivocally established through research that the period up to two years is the most potent for forming and establishing the basis of later development. This paper summarizes the findings of two research studies on infant care in India that began in July 1988 and culminated in March 1989 under my guidance. The two studies are linked in their final implications for infant stimulation and in their role in providing insights into changing trends in infant-care in India.

In study I patterns of infant caregiving practiced by fathers were investigated. Study II looked into infant-care practices in Punjabi families where the grandmother lived with the young parents.  相似文献   
59.
This communication highlights scleral dellen as an unusual complication of strabismus surgery in a 55-year-old hypertensive male. The clinical significance, differential diagnosis and management of this condition has been discussed.  相似文献   
60.
1,2,3,4-Tetrahydro-7,12-dimethylbenz[a]anthracene (THDMBA) is an animal carcinogen which lacks an aromatic bay-region and shows promise as a model to investigate non-classical mechanisms of carcinogenesis. The fluorine-substituted derivatives at positions 5 and 6 on the B-ring exhibit a striking range of oncogenic potential wherein the 6F-THDMBA is twice as potent as the parent carcinogen, but the 5F-THDMBA is virtually inactive. To study structure-reactivity relationships for these fluorine regioisomers, we have determined the three-dimensional structures of the compounds by single-crystal X-ray diffraction. These crystal structures are the first such to be reported for any monofluoro anthracene (or pyrene) derivative. The partially-reduced A-ring exists in both enantiomeric half-chair conformers in the crystalline state, and the compounds have quasi-planar anthracene ring systems which exhibit a right-handed twist in the 'beta'-conformer, with the expected opposite twist in the other. A complete analysis of bond lengths, bond angles and torsion angles is presented. Preliminary electrostatic potentials have been derived from the X-ray data sets, and the results indicate significant differences in potential between 5F- and 6F-THDMBA at positions near the partially reduced bay region. Such results are likely to be of importance in the understanding of metabolic activation to reactive intermediates capable of bonding covalently to DNA.  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