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   2112565篇
  免费   171453篇
  国内免费   7617篇
耳鼻咽喉   27453篇
儿科学   70454篇
妇产科学   58646篇
基础医学   297928篇
口腔科学   58956篇
临床医学   192378篇
内科学   422727篇
皮肤病学   49422篇
神经病学   171823篇
特种医学   84680篇
外国民族医学   568篇
外科学   324262篇
综合类   50634篇
现状与发展   2篇
一般理论   761篇
预防医学   169096篇
眼科学   46843篇
药学   150430篇
  7篇
中国医学   3862篇
肿瘤学   110703篇
  2018年   21698篇
  2016年   19934篇
  2015年   22287篇
  2014年   31107篇
  2013年   47139篇
  2012年   59641篇
  2011年   63704篇
  2010年   39123篇
  2009年   37566篇
  2008年   59532篇
  2007年   63449篇
  2006年   64669篇
  2005年   62491篇
  2004年   60152篇
  2003年   58252篇
  2002年   55642篇
  2001年   99682篇
  2000年   102351篇
  1999年   85720篇
  1998年   25360篇
  1997年   22752篇
  1996年   23545篇
  1995年   23401篇
  1994年   21752篇
  1993年   20330篇
  1992年   70543篇
  1991年   68836篇
  1990年   66678篇
  1989年   64036篇
  1988年   58988篇
  1987年   58415篇
  1986年   54906篇
  1985年   53097篇
  1984年   40325篇
  1983年   33940篇
  1982年   21004篇
  1981年   18943篇
  1980年   17764篇
  1979年   36747篇
  1978年   26701篇
  1977年   22421篇
  1976年   20973篇
  1975年   21845篇
  1974年   25995篇
  1973年   25031篇
  1972年   23085篇
  1971年   21358篇
  1970年   19712篇
  1969年   18483篇
  1968年   17126篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
801.
L D Keith  J C Crabbe 《Alcohol》1992,9(6):529-533
The intent of this study was to determine whether chronic ethanol (EtOH) vapor inhalation, with or without adjunct pyrazole (PYR) administration, was stressful in mice, as defined by increases in plasma corticosterone (CORT) concentration. Mice were randomly assigned to groups differentiated both on the basis of EtOH vapor exposure and the presence or absence of PYR administration. Blood samples for blood EtOH concentration (BEC) and plasma CORT concentration were obtained from mice after 72-96 hours of treatment. Mice were sacrificed after 96 hours of treatment and body and adrenal weight determined. BEC was significantly higher in PYR-treated animals and animals treated with the higher EtOH vapor concentration. Plasma CORT was elevated in proportion to BEC; however, other nonspecific stresses, in particular that of PYR administration, also elevated plasma CORT. Nonspecific stresses associated with this protocol may reduce the generality of these observations. Nevertheless, the high correlation between BEC and plasma CORT concentration in the PYR groups indicates that, with suitable control groups, the PYR-EtOH vapor inhalation approach is viable for studies concerned with EtOH effects on hypothalamic-anterior pituitary-adrenocortical function.  相似文献   
802.
In 1985 an outbreak of ornithosis affected 13 of 80 (16%) workers in a duck-processing plant. New employees were three times more likely to become cases than established employees. The highest attack rate was in those on the production line. Following the outbreak, an occupational health scheme was set up to monitor the health of new recruits to the company. Serological evidence of recent infection was demonstrated in 18 of 37 (49%) new employees tested in the first 3 months of employment. Five (14%) also had clinical evidence of ornithosis. Veterinary investigation of the ducks demonstrated a high proportion with asymptomatic chlamydial infection. It is suggested that ornithosis may be more common in duck processors than is currently supposed. Strategies to reduce occupational risks are discussed.  相似文献   
803.
Exposure to cadmium via the diet is known to depend to a large extent on the intake of cereal grains, particularly the high-fibre fractions of wheat. Subjects with low iron status absorb more cadmium than those with better iron status. The purpose of the present study was to determine to what extent cadmium accumulation in human placenta is affected by the intake of grain fibre and maternal iron status during pregnancy. Thirty-nine pregnant women participated in the study. In each trimester the women were requested to complete a dietary history and to allow blood samples to be taken for haemoglobin, serum ferritin and serum thiocyanate determinations, the latter as a marker for smoking. At delivery the whole placenta was taken for the determination of the cadmium concentration. The 32 women who had serum thiocyanate levels less than 70 mumol/l, who had completed at least one dietary history and from whom a blood sample was obtained in the third trimester, were included in the final statistical analyses. In the group of women who consumed less than the median intake of grain fibre and had more than 15 micrograms ferritin/l serum in the third trimester, the placenta cadmium concentration was nearly half that in the placentae of women who had consumed more grain fibre or had lower iron status in late pregnancy.  相似文献   
804.
805.
806.
Fractures of the distal humerus.   总被引:4,自引:0,他引:4  
J B Jupiter  D K Mehne 《Orthopedics》1992,15(7):825-833
We present a rational approach to the classification and surgical management of intraarticular fractures of the distal humerus. The fractures are classified on the basis of the surgical anatomy of the distal humerus, which is divided into two skeletal columns held together by the trochlea. The basic surgical aim is to restore all three elements with sufficient stability to permit functional movement. The surgical tactics are presented in detail.  相似文献   
807.
LUMBOVERTEBRAL SYNDROME AFTER EXTRADURAL BLOOD PATCH   总被引:2,自引:1,他引:1  
We describe a patient who developed an immobilizing lumbovertebralsyndrome after an extradural blood patch and who was hospitalizedwith a. suspected extradural abscess. An infectious aetiologyof the persistent backache could be excluded and the patientrecovered with analgesics and physiotherapy. The probable aetiologyis discussed.  相似文献   
808.
809.
PATIENTS AND METHOD: The aim of the present study was to contribute to a more accurate indication and better integration of developing third molar transplantation into orthodontic space management, using the results gleaned from the authors' own pool of patients. For this purpose, a clinical and radiographic examination of 61 transplanted developing molars in 57 patients was carried out after an average of 3.3 years. RESULTS: The overall success rate was 85%. Failure was due in 10% of cases to impaired periodontal healing (inflammatory root resorption, ankylosis, or increased pocket probing depths) and in 5% of cases to insufficient or arrested postoperative root development accompanied by increased transplant mobility. The incidence of postoperative cessation of further root development was significantly higher (p = 0.011) in transplants at early developmental stages, which also had a negative impact on the final root length, the crown-root ratio and the mobility values of these transplants. CONCLUSIONS: The transplantation of developing third molars should be given stronger consideration in treatment plans for orthodontic space management although it represents a real alternative to orthodontic space closure only in exceptional cases. However, unlike implantological or prosthodontic treatment, it offers an opportunity to replace a missing or non-retainable tooth with a patient's own vital and fully functional tooth, provided the appropriate transplant is selected.  相似文献   
810.
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