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   4654篇
  免费   229篇
  国内免费   21篇
耳鼻咽喉   51篇
儿科学   567篇
妇产科学   120篇
基础医学   439篇
口腔科学   84篇
临床医学   280篇
内科学   943篇
皮肤病学   71篇
神经病学   222篇
特种医学   154篇
外科学   775篇
综合类   79篇
预防医学   175篇
眼科学   243篇
药学   330篇
中国医学   19篇
肿瘤学   352篇
  2023年   45篇
  2022年   72篇
  2021年   108篇
  2020年   75篇
  2019年   96篇
  2018年   131篇
  2017年   79篇
  2016年   126篇
  2015年   139篇
  2014年   204篇
  2013年   229篇
  2012年   383篇
  2011年   340篇
  2010年   213篇
  2009年   165篇
  2008年   243篇
  2007年   252篇
  2006年   204篇
  2005年   198篇
  2004年   187篇
  2003年   189篇
  2002年   170篇
  2001年   94篇
  2000年   92篇
  1999年   77篇
  1998年   38篇
  1997年   25篇
  1996年   30篇
  1995年   22篇
  1994年   29篇
  1993年   15篇
  1992年   56篇
  1991年   65篇
  1990年   37篇
  1989年   38篇
  1988年   30篇
  1987年   34篇
  1986年   35篇
  1985年   37篇
  1984年   21篇
  1983年   14篇
  1981年   22篇
  1979年   20篇
  1978年   20篇
  1977年   30篇
  1976年   34篇
  1975年   14篇
  1974年   18篇
  1969年   12篇
  1968年   13篇
排序方式: 共有4904条查询结果,搜索用时 15 毫秒
1.
2.
3.
Semen analysis was performed on 48 men who had undergone orchiopexy, 40 for unilateral impalpable testes and 8 for bilateral impalpable testes. Patients with unilateral impalpable testes had varying sperm analysis; 18 (86%) of the 23 patients with unilateral impalpable canalicular testes had normal sperm analysis. All patients with bilateral impalpable testes were azoospermic. The subsequent quality of the semen is dependent upon the original anatomical positions of the undescended testes.  相似文献   
4.
Malignant schwannoma (malignant peripheral nerve sheath tumour, MPNST) is a rare high-grade tumour arising from peripheral nerves. We report the case of a 3-year-old male who presented with a non-tender lesion on the dorsum of his penis. The lesion was excised and a formal circumcision performed. Histology of the lesion revealed a spindle cell tumour. Immunohistochemistry showed the tumour cells to be strongly positive for S100 and Vimentin. A diagnosis of intermediate grade malignant peripheral nerve sheath tumour was made. Malignant schwannoma is rare in children and is previously unreported in the penis in the paediatric age group without evidence of neurofibromatosis.  相似文献   
5.
Patients with acute brain pathology requiring ferromagnetic bio-medical implants for on-going invasive monitoring are largely excluded from the benefits of MRI scanning. We evaluated the behaviour of a thermal diffusion cortical blood flow (TD-CBF) sensor both in vitro (phantom gelatin model) and in vivo environments in a high field strength MRI system.Two baboons underwent cranial subdural implantation of 2 TD-CBF sensors/hemisphere and a single left parietal sensor was implanted subcortically to determine any deleterious effects. Using standard MRI sequences, artefact size, thermal effects, current generation, movement and reliability of recordings were assessed during scanning.The deflection forces were negligible, no observable thermal effects were demonstrated, while wide fluctuations in cerebral blood flow recordings were recorded. Mean image artefact size for implanted sensors was 6 times larger than in vitro. Patients with an implanted TD-CBF sensor may be safely imaged provided the device is disconnected. The MRI images obtained are of an acceptable quality.  相似文献   
6.
7.
8.
Purpose. The effect of retrograde cerebral perfusion on the incidence of stroke and death among patients undergoing repair of aneurysms of the ascending aorta and transverse arch was determined.

Material and Methods. Between January 1991 and March 1995, 161 patients were operated on for aneurysms of the ascending aorta and transverse arch. Thirty-three of the patients (20%) had an aneurysm of the ascending aorta only and 128 (80%) had aneurysms of both the ascending aorta and the transverse arch. All the patients underwent cardiopulmonary bypass, profound hypothermia, and circulatory arrest, and 120 (74%) also underwent retrograde cerebral perfusion. Median pump time was 143 minutes (range, 21 to 461 minutes). Median circulatory arrest time was 42 minutes (range, 8 to 111 minutes), and median myocardial ischemic time was 71 minutes (range, 14 to 306 minutes).

Results. The overall 30-day mortality rate was 6% (9 patients) and the incidence of stroke was 4% (7 patients). The use of retrograde cerebral perfusion demonstrated a protective effect against stroke (3 of 120 patients, or 3%) compared with no retrograde cerebral perfusion (4 of 41 patients, or 9%; odds ratio, 0.24; confidence interval, 0.06 to 0.99; p < 0.049). This was most significant in patients more than 70 years of age; none of the 36 elderly patients who received retrograde cerebral perfusion had a stroke, compared with 3 of the 13 (23%) who did not (p < 0.003). Only pump time was associated with an increased risk of stroke (odds ratio, 1.01; 95% confidence interval, 1.00 to 1.02; p < 0.005). Pump time also was associated with increased mortality (odds ratio, 1.01; 95% confidence interval, 1.00 to 1.02; p < 0.008).

Conclusion. Retrograde cerebral perfusion decreased the incidence of stroke in patients undergoing repair of aneurysms of the ascending aorta and transverse arch.  相似文献   

9.
In most Special Care Neonatal Units (SCNUs) in India, mothers are excluded from the care of their sick babies for fear of over-crowding and dislocation. We have attempted to study the feasibility of involving mothers in the care of their babies admitted for neonatal septicemia and to analyse whether this changed the sepsis related case fatality rate. The study material consisted of 158 neonates with blood culture positive neonatal septicemia whose mothers were actively involved in their care during their stay in the SCNU of LNJPN Hospital throughout 1987-88. The mothers lived in with their sick neonates and were extremely useful in feeding, cleaning, and monitoring for some important signs and symptoms. There were no epidemics of infection in the nursery during this period. All the babies discharged were receiving breast feeds, and the mothers were confident in taking care of them before discharge. The mortality in this group was 43%. The onset of septicemia was most often in the first week (36%) being 25.9% in second week, 26.6% in the third, and 11.4% in the fourth. Mortality was maximum (64.5%) when the onset of illness was in the first 3 days. Klebsiella and S. aureus were commonly isolated organisms (38.6 and 21.5%, respectively). Gram negative organisms were isolated in 66.5% cases with higher mortality in this group. Nearly 46% of the babies weighed 2 kg or less, with a mortality of 60.2% compared to 28.2% in those more than 2 kg. Only 3 to 5% and 40 to 66.7% of Gram negative and 23 and 70% of Gram positive organisms were sensitive to ampicillin and gentamicin, respectively.  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