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   2894428篇
  免费   233782篇
  国内免费   5502篇
耳鼻咽喉   42742篇
儿科学   88420篇
妇产科学   78408篇
基础医学   409402篇
口腔科学   84134篇
临床医学   262130篇
内科学   561221篇
皮肤病学   58862篇
神经病学   242987篇
特种医学   115989篇
外国民族医学   1042篇
外科学   440251篇
综合类   72583篇
现状与发展   3篇
一般理论   1171篇
预防医学   233820篇
眼科学   69508篇
药学   216186篇
  4篇
中国医学   5375篇
肿瘤学   149474篇
  2018年   28609篇
  2016年   24533篇
  2015年   27866篇
  2014年   40232篇
  2013年   61435篇
  2012年   82695篇
  2011年   87192篇
  2010年   51317篇
  2009年   49072篇
  2008年   82726篇
  2007年   88642篇
  2006年   89234篇
  2005年   87112篇
  2004年   84318篇
  2003年   81421篇
  2002年   80171篇
  2001年   130024篇
  2000年   134503篇
  1999年   113906篇
  1998年   33491篇
  1997年   30562篇
  1996年   30130篇
  1995年   29135篇
  1994年   27445篇
  1993年   25571篇
  1992年   93026篇
  1991年   89784篇
  1990年   86896篇
  1989年   83719篇
  1988年   78024篇
  1987年   77036篇
  1986年   72879篇
  1985年   69949篇
  1984年   53451篇
  1983年   45724篇
  1982年   28243篇
  1981年   25250篇
  1980年   23767篇
  1979年   51279篇
  1978年   36324篇
  1977年   30601篇
  1976年   28600篇
  1975年   30332篇
  1974年   37528篇
  1973年   35874篇
  1972年   33642篇
  1971年   31079篇
  1970年   29399篇
  1969年   27656篇
  1968年   25154篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
53.
54.
Endoscopic clips have been used mainly for control of gastrointestinal (GI) bleeding and occasionally for closure of GI perforations. However, closure of spontaneous esophageal perforation (Boerhaave's syndrome) by clipping has not been reported. We described successful non-surgical closure of spontaneous esophageal perforation by endoscopic clipping in a patient with bilateral pyopneumothorax and septicemia.  相似文献   
55.
56.
57.
58.
CONTEXT: Although the nonmedical use of stimulant drugs such as cocaine and methamphetamine is increasingly common in many rural areas of the United States, little is known about the health beliefs of people who use these drugs. PURPOSE: This research describes illicit stimulant drug users' views on health and health-related concepts that may affect their utilization of health care services. METHODS: A respondent-driven sampling plan was used to recruit 249 not-in-treatment, nonmedical stimulant drug users who were residing in 3 rural counties in west central Ohio. A structured questionnaire administered by trained interviewers was used to collect information on a range of topics, including current drug use, self-reported health status, perceived need for substance abuse treatment, and beliefs about health and health services. FINDINGS: Participants reported using a wide variety of drugs nonmedically, some by injection. Alcohol and marijuana were the most commonly used drugs in the 30 days prior to the interview. Powder cocaine was used by 72.3% of the sample, crack by 68.3%, and methamphetamine by 29.7%. Fair or poor health status was reported by 41.3% of the participants. Only 20.9% of the sample felt they needed drug abuse treatment. Less than one third of the sample reported that they would feel comfortable talking to a physician about their drug use, and 65.1% said they preferred taking care of their problems without getting professional help. CONCLUSIONS: Stimulant drug users in rural Ohio are involved with a range of substances and hold health beliefs that may impede health services utilization.  相似文献   
59.
PURPOSE: In children with locally advanced or recurrent malignant tumours, prognosis can be improved by regional deep hyperthermia (RHT) in combination with platin-based chemotherapy. However, because of the increasing number of patients that achieve long-time remission with this therapy, it is necessary to evaluate long-term sequelae of thermochemotherapy. During the years 1993-2004 one has observed avascular osteonecrosis (AON) of the femoral head after RHT in seven children with pelvic germ cell tumours or rhabdomyosarcomas. METHODS: Although AON may develop in patients with malignancies treated with chemo- or radiotherapy alone, RHT might nevertheless contribute to the occurrence of AON. In order to determine potential risk factors for AON after RHT, this study analysed the relationship of AON to the patient's age, medical history and treatment parameters such as thermal dose equivalent and power output. RESULTS AND CONCLUSIONS: In the present study AON was associated with young age as well as intensity of hyperthermia indicated by high power levels that exceed 20 W per kg body weight and/or application of eight or more heat sessions as well as additional radiotherapy. Based on this observation, it was assumed that an optimized three dimensional thermal field modelling may be helpful to avoid hazardous temperatures in the femoral heads during RHT treatment and to reduce AON of the femoral heads.  相似文献   
60.
The purpose of this study was to determine fixed cut-off points for forced expiratory volume in one second (FEV(1))/FEV(6) and FEV(6) as an alternative for FEV(1)/forced vital capacity (FVC) and FVC in the detection of obstructive and restrictive spirometric patterns, respectively. For the study, a total of 11,676 spirometric examinations, which took place on Caucasian subjects aged between 20-80 yrs, were analysed. Receiver-operator characteristic curves were used to determine the FEV(1)/FEV(6) ratio and FEV(6) value that corresponded to the optimal combination of sensitivity and specificity, compared with the commonly used fixed cut-off term for FEV(1)/FVC and FVC. The data from the current study indicate that FEV(1)/ FEV(6) <73% and FEV(6) <82% predicted can be used as a valid alternative for the FEV(1)/FVC <70% and FVC <80% pred cut-off points for the detection of obstruction and restriction, respectively. The statistical analysis demonstrated very good, overall, agreement between the two categorisation schemes. For the spirometric diagnosis of airway obstruction (prevalence of 45.9%), FEV(1)/FEV(6) sensitivity and specificity were 94.4 and 93.3%, respectively; the positive and negative predictive values were 92.2 and 95.2%, respectively. For the spirometric detection of a restrictive pattern (prevalence of 14.9%), FEV(6) sensitivity and specificity were 95.9 and 98.6%, respectively; the positive and negative predictive values were 92.2 and 99.3%, respectively. This study demonstrates that forced expiratory volume in one second/forced expiratory volume in six seconds <73% and forced expiratory volume in six seconds <82% predicted, can be used as valid alternatives to forced expiratory volume in one second/forced vital capacity <70% and forced vital capacity <80% predicted, as fixed cut-off terms for the detection of an obstructive or restrictive spirometric pattern in adults.  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