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   1030篇
  免费   42篇
  国内免费   3篇
耳鼻咽喉   14篇
儿科学   38篇
妇产科学   57篇
基础医学   94篇
口腔科学   20篇
临床医学   91篇
内科学   195篇
皮肤病学   11篇
神经病学   33篇
特种医学   248篇
外科学   67篇
综合类   20篇
预防医学   55篇
眼科学   17篇
药学   56篇
  1篇
中国医学   14篇
肿瘤学   44篇
  2022年   4篇
  2021年   10篇
  2019年   7篇
  2018年   12篇
  2017年   14篇
  2016年   12篇
  2015年   20篇
  2014年   21篇
  2013年   26篇
  2012年   28篇
  2011年   44篇
  2010年   29篇
  2009年   34篇
  2008年   31篇
  2007年   35篇
  2006年   39篇
  2005年   22篇
  2004年   7篇
  2003年   18篇
  2002年   13篇
  2001年   6篇
  2000年   19篇
  1999年   9篇
  1998年   37篇
  1997年   34篇
  1996年   39篇
  1995年   48篇
  1994年   39篇
  1993年   39篇
  1992年   9篇
  1991年   10篇
  1990年   22篇
  1989年   40篇
  1988年   26篇
  1987年   34篇
  1986年   40篇
  1985年   23篇
  1984年   19篇
  1983年   16篇
  1982年   15篇
  1981年   19篇
  1980年   18篇
  1979年   9篇
  1978年   15篇
  1977年   17篇
  1976年   13篇
  1975年   12篇
  1958年   4篇
  1957年   6篇
  1954年   2篇
排序方式: 共有1075条查询结果,搜索用时 15 毫秒
41.
42.
OBJECT: The results of two longitudinal studies of growth rates of vestibular schwannomas (VSs) in patients with neurofibromatosis Type 2 (NF2) differ as to whether VS growth rates decrease or increase with increasing patient age. The authors undertook this study to assess the relationship between VS growth rates and patient age and type of constitutional NF2 mutation; they also examined variability in VS growth rates among multiple patients in families with NF2. METHODS: Gadolinium-enhanced magnetic resonance images obtained in 18 patients with inherited NF2 from 11 unrelated families were retrospectively analyzed. The patients had been observed for a median of 4 years. Volumes of the VSs were measured using a two-component box model (intrameatal and extrameatal parts measured separately). Single-strand conformation polymorphism analysis and Southern blot analysis were used to identify constitutional NF2 mutations. Growth rates of the VSs were highly variable, but tended to decrease with increasing patient age both at onset of signs or symptoms of NF2 (r2 = 0.35, p = 0.026) and at diagnosis (r2 = 0.33, p = 0.012). The VS growth rates did not vary significantly with the type of constitutional NF2 mutation or the number of non-VS cerebral or spinal tumors. The VS growth rates were highly variable within families and did not correspond to clinical indices of NF2 disease severity, such as patient age at symptom onset and the number of non-VS cerebral and spinal tumors. CONCLUSIONS: The growth rates of VSs in patients with NF2 are highly variable, but tend to decrease with increasing patient age. Clinical treatment of multiple patients in families with NF2 cannot be based on the expectations of similar VS growth rates, even when other clinical aspects of disease severity are similar.  相似文献   
43.
OBJECT: The factors that determine the growth rates of vestibular schwannomas (VSs) in patients with neurofibromatosis Type 2 (NF2) are unknown. The authors undertook this study to determine if clinical factors or type of constitutional NF2 mutation were associated with VS growth rates in cases of NF2. METHODS: The authors reviewed serial gadolinium-enhanced magnetic resonance (MR) images of the head and full spine of 37 patients with sporadic NF2 who had been observed over periods ranging from 0.2 to 8 years (median 3.9 years) at a specialized referral clinic for NF2. A box model was used to calculate VS volumes so that tumor growth rates could be estimated. Temperature-gradient gel electrophoresis was used to screen for constitutional NF2 mutations. The VS growth rates tended to decrease with increasing patient age at onset of signs or symptoms (r2 = 0.23, p = 0.003) and at the time the baseline gadolinium-enhanced MR image was obtained (r2 = 0.38, p < 0.001). The authors did not find significant associations between VS growth rates and the number of non-VS cerebral or spinal tumors or different types of constitutional NF2 mutations. CONCLUSIONS: There is considerable variability in growth rates of VSs in patients with NF2, but they tend to be higher in patients who are younger at onset of signs or symptoms.  相似文献   
44.

Background  

There is evidence that certain mutations in the double-strand break repair pathway ataxia-telangiectasia mutated gene act in a dominant-negative manner to increase the risk of breast cancer. There are also some reports to suggest that the amino acid substitution variants T2119C Ser707Pro and C3161G Pro1054Arg may be associated with breast cancer risk. We investigate the breast cancer risk associated with these two nonconservative amino acid substitution variants using a large Australian population-based case–control study.  相似文献   
45.
Monascus purpureus is a fungus that has been tradi-tionally used in China for thousands of years to produce ricewine . Traditionally the fungus is used to ferment non-gluti-nous cooking of rice ,to produce a kind of famous red ricewine .Its main traditional indications consist of disordersdue to the accumulation of fats (nosologically linked withthe problems of stasis of circulation in traditional Chinesemedicine) ,liver disorders and some forms of tumor as ithelps i mprove the circulation of …  相似文献   
46.
47.
Data on body composition in conjunction with reference centiles are helpful in identifying the severity of growth and nutritional disorders in infancy and for evaluating the adequacy of treatment given during this important period of rapid growth. Total body fat (TBF) and fat-free mass (FFM) were estimated from total body electrical conductivity (TBEC) measurements in 423 healthy term Caucasian infants, aged 14-379 days. Cross sectional age, weight, and length related centile standards are presented for TBF and FFM. Centiles were calculated using Altman's method, based on polynomial regression and modelling of the residual variation. The TBF percentage steeply increased during the first half year of life, and slowly declined beyond this age. Various simple TBEC derived anthropometric prediction equations for TBF and FFM are available to be used in conjunction with these standards. Regression equations for the P50 and the residual SD, depending on age, weight, or length, are provided for constructing centile charts and calculating standard deviation scores.  相似文献   
48.
This study of etoposide in thyroid cancer was designed to determine the activity and toxicity of etoposide in a variety of inoperable, thyroid hormone insensitive, and radio-iodine resistant primary cancers of the thyroid. The patients were required to have an ECOG performance status of at least 3 and no previous exposure to chemotherapy. The etoposide was given at a dose of 140 mg/m2 daily for 3 days and every 3 weeks until progression. The study was closed after 18 months because of poor accrual. There were no responses seen among the 10 patients accrued. The toxicity was primarily hematologic. There was no evidence of activity of etoposide in thyroid carcinoma, although this study lacked significant power because of the poor accrual.  相似文献   
49.
50.
Neural networks in ventilation-perfusion imaging   总被引:2,自引:0,他引:2  
Fisher  RE; Scott  JA; Palmer  EL 《Radiology》1996,198(3):699
  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