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   2374712篇
  免费   195041篇
  国内免费   4210篇
耳鼻咽喉   34264篇
儿科学   72746篇
妇产科学   62928篇
基础医学   334880篇
口腔科学   67523篇
临床医学   215527篇
内科学   468596篇
皮肤病学   47930篇
神经病学   200783篇
特种医学   95965篇
外国民族医学   886篇
外科学   360397篇
综合类   56218篇
现状与发展   1篇
一般理论   977篇
预防医学   190612篇
眼科学   55463篇
药学   177524篇
  4篇
中国医学   4366篇
肿瘤学   126373篇
  2018年   24207篇
  2016年   20576篇
  2015年   23282篇
  2014年   33536篇
  2013年   50837篇
  2012年   68742篇
  2011年   72276篇
  2010年   42474篇
  2009年   40864篇
  2008年   68759篇
  2007年   73099篇
  2006年   73997篇
  2005年   72038篇
  2004年   69332篇
  2003年   67012篇
  2002年   66258篇
  2001年   112449篇
  2000年   116527篇
  1999年   98334篇
  1998年   27859篇
  1997年   25523篇
  1996年   25450篇
  1995年   24613篇
  1994年   23163篇
  1993年   21555篇
  1992年   79387篇
  1991年   76393篇
  1990年   73575篇
  1989年   70842篇
  1988年   65846篇
  1987年   64801篇
  1986年   61334篇
  1985年   58400篇
  1984年   44222篇
  1983年   37658篇
  1982年   22887篇
  1981年   20332篇
  1980年   19034篇
  1979年   41301篇
  1978年   28986篇
  1977年   24349篇
  1976年   22832篇
  1975年   23965篇
  1974年   29639篇
  1973年   28046篇
  1972年   26228篇
  1971年   24151篇
  1970年   22755篇
  1969年   21088篇
  1968年   19137篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
63.
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   
64.
65.
66.
67.
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   
68.
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   
69.
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   
70.
The absence of the temporary incisors could be to a genetic illness or to some multiple premature extractions. These extractions are the aftermaths of the carious lesions or some traumatisms underwent by the temporary incisors. Beyond measure the loss of the space, the premature loss some temporary incisors very often assign the relational development of the child and disturb its psychological development and the aesthetic function. Across some cases clinics, the authors show that the replacement of the temporary incisors is the therapeutic ideal solution. Indeed, the child prosthesis, replacing the temporary absent incisors, solves the psychological, aesthetic and relational problems of the child.  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