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   2232406篇
  免费   180140篇
  国内免费   4133篇
耳鼻咽喉   31689篇
儿科学   71017篇
妇产科学   64527篇
基础医学   318852篇
口腔科学   66317篇
临床医学   197030篇
内科学   430838篇
皮肤病学   47060篇
神经病学   181489篇
特种医学   89620篇
外国民族医学   632篇
外科学   341558篇
综合类   58594篇
现状与发展   5篇
一般理论   765篇
预防医学   174217篇
眼科学   52297篇
药学   168191篇
  3篇
中国医学   4258篇
肿瘤学   117720篇
  2018年   20488篇
  2015年   20979篇
  2014年   29256篇
  2013年   44685篇
  2012年   60307篇
  2011年   63523篇
  2010年   37416篇
  2009年   35550篇
  2008年   60542篇
  2007年   64647篇
  2006年   65097篇
  2005年   63553篇
  2004年   62543篇
  2003年   59951篇
  2002年   58400篇
  2001年   99562篇
  2000年   102570篇
  1999年   87128篇
  1998年   24695篇
  1997年   22590篇
  1996年   22456篇
  1995年   21679篇
  1994年   20482篇
  1993年   19263篇
  1992年   72662篇
  1991年   70581篇
  1990年   69099篇
  1989年   66752篇
  1988年   62455篇
  1987年   61459篇
  1986年   58460篇
  1985年   56574篇
  1984年   42904篇
  1983年   36899篇
  1982年   22500篇
  1981年   20313篇
  1980年   18976篇
  1979年   41982篇
  1978年   29632篇
  1977年   24958篇
  1976年   23289篇
  1975年   24848篇
  1974年   30639篇
  1973年   29384篇
  1972年   27283篇
  1971年   25708篇
  1970年   23874篇
  1969年   22736篇
  1968年   20641篇
  1967年   18846篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
83.
84.
85.
86.
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   
87.
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   
88.
89.
Carbon monoxide (CO), a byproduct of heme catalysis, was shown to have potent cytoprotective and anti-inflammatory effects. In vivo recipient CO inhalation at low concentrations prevented ischemia/reperfusion (I/R) injury associated with small intestinal transplantation (SITx). This study examined whether ex vivo delivery of CO in University of Wisconsin (UW) solution could ameliorate intestinal I/R injury. Orthotopic syngenic SITx was performed in Lewis rats after 6 h cold preservation in control UW or UW that was bubbled with CO gas (0.1-5%) (CO-UW). Recipient survival with intestinal grafts preserved in 5%, but not 0.1%, CO-UW improved to 86.7% (13/15) from 53% (9/17) with control UW. At 3 h after SITx, grafts stored in 5% CO-UW showed improved intestinal barrier function, less mucosal denudation and reduced inflammatory mediator upregulation compared to those in control UW. Preservation in CO-UW associated with reduced vascular resistance (end preservation), increased graft cyclic guanosine monophosphate levels (1 h), and improved graft blood flow (1 h). Protective effects of CO-UW were reversed by ODQ, an inhibitor of soluble guanylyl cyclase. In vitro culture experiment also showed better preservation of vascular endothelial cells with CO-UW. The study suggests that ex vivo CO delivery into UW solution would be a simple and innovative therapeutic strategy to prevent transplant-induced I/R injury.  相似文献   
90.
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