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   2900篇
  免费   150篇
  国内免费   5篇
耳鼻咽喉   15篇
儿科学   175篇
妇产科学   56篇
基础医学   234篇
口腔科学   62篇
临床医学   162篇
内科学   552篇
皮肤病学   47篇
神经病学   224篇
特种医学   41篇
外科学   732篇
综合类   104篇
预防医学   121篇
眼科学   112篇
药学   144篇
中国医学   21篇
肿瘤学   253篇
  2023年   31篇
  2022年   37篇
  2021年   106篇
  2020年   53篇
  2019年   68篇
  2018年   96篇
  2017年   58篇
  2016年   88篇
  2015年   70篇
  2014年   103篇
  2013年   140篇
  2012年   211篇
  2011年   175篇
  2010年   128篇
  2009年   79篇
  2008年   135篇
  2007年   143篇
  2006年   119篇
  2005年   130篇
  2004年   128篇
  2003年   117篇
  2002年   84篇
  2001年   99篇
  2000年   78篇
  1999年   66篇
  1998年   36篇
  1997年   39篇
  1996年   25篇
  1995年   20篇
  1994年   16篇
  1993年   7篇
  1992年   33篇
  1991年   35篇
  1990年   23篇
  1989年   32篇
  1988年   28篇
  1987年   18篇
  1986年   16篇
  1985年   26篇
  1984年   19篇
  1983年   15篇
  1982年   8篇
  1981年   7篇
  1980年   13篇
  1979年   9篇
  1978年   9篇
  1976年   9篇
  1974年   15篇
  1973年   7篇
  1972年   9篇
排序方式: 共有3055条查询结果,搜索用时 15 毫秒
141.
142.
Age estimation is a prerequisite in forensic medicine, paediatric endocrinology and orthodontic treatment. Dental development has been proven to be suitable for age determination in children because of its lower variability. The aim of this study was to evaluate the applicability of using the open apex method proposed by Cameriere et al. for age estimation in Indian children. Digitalized panoramic radiographs were retrieved from the Department of Oral Medicine & Radiology of 558 Indian children (261 girls, 297 boys) with an age range from 5 to 15 years. The seven left permanent mandibular teeth were evaluated for length and open apices. Dental maturity was evaluated using measurements of the seven left permanent mandibular teeth (xi = Ai/Li, i = 1,...,7), the sum of the normalized open apices (s) and the number (N0) of teeth with root development complete. Using a stepwise multiple regression model, a relationship between open apices, N0 and age was evaluated. Statistical analysis revealed high accuracy with the morphological variables explaining 88.5% of the variations in estimated chronological age. This research suggests an open apex method could be successful for age estimation in Indian children and could be applied in legal issues pertaining to forensic medicine.  相似文献   
143.
Randomized controlled trials have become the most respected scientific tool to measure the effectiveness of a medical therapy. The design, conduct and analysis of randomized controlled trials were developed by Sir Ronald A. Fisher, a mathematician in Great Britain. Fisher propounded that the process of randomization would equally distribute all the known and even unknown covariates in the two or more comparison groups, so that any difference observed could be ascribed to treatment effect. Today, we observe that in many situations, this prediction of Fisher does not stand true; hence, adaptive randomization schedules have been designed to adjust for major imbalance in important covariates. Present essay unravels some weaknesses inherent in Fisherian concept of randomized controlled trial.  相似文献   
144.
145.
Spontaneous bacterial peritonitis (SBP), a common complication of cirrhosis of liver, might result from translocation of bacteria from the small bowel. However, there is scanty data on frequency of small intestinal bacterial overgrowth (SIBO) in patients with cirrhosis of the liver. There are no data on SIBO in patients with extra-hepatic portal venous obstruction (EHPVO) in the literature. A total of 174 patients with cirrhosis of the liver, 28 with EHPVO and 51 healthy controls were studied for SIBO using glucose hydrogen breath test (GHBT). Persistent rise in breath hydrogen 12 ppm above basal (at least two readings) was considered diagnostic of SIBO. Of 174 patients (age 47.2 ± 11.9 years, 80.5% male) with cirrhosis due to various causes, 67 (38.5%) were in Child’s class A, 70 (40.2%) class B and 37 (21.7%) class C. Of the 174 patients with cirrhosis, 42 (24.14%) had SIBO as compared to 1 of 51 (1.9%) healthy controls (P < 0.0001). Patients with EHPVO had similar frequency of SIBO compared to healthy controls [2/28 (7.14%) vs 1/51 (1.97%), P = ns]. Frequency of SIBO in Child’s A, B and C was comparable [13 (18.6%) vs 16 (23.9%) and 13 (35.1%), respectively; P = ns]. Presence of SIBO were not related to ascites, etiology of cirrhosis, and degree of liver dysfunction. SIBO is common in patients with cirrhosis of the liver. Patients with EHPVO do not have higher frequency of SIBO than healthy subjects. SIBO in cirrhosis is not related to the degree of derangement in liver function or of portal hypertension.  相似文献   
146.
A 53-year-old man presented with a sudden onset severe headache associated with ataxia. His family observed labile emotions and frequent episodes of crying. Investigations revealed a pontine cavernoma with evidence of bleeding. The lesion was treated conservatively. Over approximately 6 months, the patient’s ataxia improved and he recovered from the crying episodes. To our knowledge, pathological crying has not been previously associated with brainstem cavernoma.  相似文献   
147.
148.
149.
PURPOSE: Liver transplant recepients (LTRs) have an increased risk of colorectal neoplasia. The mechanism responsible for this is unknown. JCV encodes for TAg and has been implicated in colorectal carcinogenesis. We hypothesized that the use of immunosuppression in LTRs facilitates activation of JCV and is responsible for the increased risk of neoplasia. EXPERIMENTAL DESIGN: JCV TAg DNA and protein expression were determined in normal colonic epithelium (n = 15) and adenomatous polyps (n = 26) from LTRs and compared with tissue samples from control patients (normal colon, n = 21; adenomas, n = 40). Apoptosis and proliferation were determined by M30 and Ki-67 immunoreactivity, respectively. RESULTS: JCV TAg DNA was found in 10 of 15 (67%) of normal colonic mucosa from LTRs compared with 5 of 21 (24%) of control normal mucosa (P = 0.025). JCV TAg DNA was detected in 16 of 26 (62%) of the adenomas from LTRs and in 20 of 40 (50%) of control adenomas. JCV TAg protein was expressed in 13 of 26 (50%) adenomas from LTRs versus 2 of 40 (5%) of adenomas from controls (P < 0.001). In adenomas from LTRs, the mean proliferative activity was higher compared with controls (60.3 +/- 3.2% versus 42.7 +/- 2.8%, P < 0.001), whereas mean apoptotic indices were lower in LTRs (0.29 +/- 0.08% versus 0.39 +/- 0.06%, P = 0.05). CONCLUSIONS: The presence of JCV in the colorectal mucosa and adenomas from LTRs, in concert with the use of immunosuppressive agents, suggests that JCV may undergo reactivation, and the subsequent TAg protein expression might explain the increased risk of colorectal neoplasia in LTRs.  相似文献   
150.
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