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   2325560篇
  免费   175437篇
  国内免费   5590篇
耳鼻咽喉   30422篇
儿科学   75804篇
妇产科学   64674篇
基础医学   344347篇
口腔科学   64936篇
临床医学   223230篇
内科学   448162篇
皮肤病学   48352篇
神经病学   191413篇
特种医学   84920篇
外国民族医学   603篇
外科学   325378篇
综合类   50440篇
现状与发展   4篇
一般理论   978篇
预防医学   197971篇
眼科学   52110篇
药学   171456篇
  12篇
中国医学   4782篇
肿瘤学   126593篇
  2019年   19163篇
  2018年   26287篇
  2017年   20031篇
  2016年   21752篇
  2015年   24953篇
  2014年   34634篇
  2013年   53505篇
  2012年   73079篇
  2011年   77793篇
  2010年   45204篇
  2009年   42509篇
  2008年   72051篇
  2007年   76729篇
  2006年   76456篇
  2005年   74359篇
  2004年   71202篇
  2003年   67960篇
  2002年   65776篇
  2001年   101828篇
  2000年   104432篇
  1999年   87989篇
  1998年   25224篇
  1997年   22932篇
  1996年   22983篇
  1995年   21808篇
  1994年   20366篇
  1993年   19088篇
  1992年   70287篇
  1991年   69220篇
  1990年   67134篇
  1989年   64244篇
  1988年   59549篇
  1987年   58394篇
  1986年   55696篇
  1985年   53106篇
  1984年   40135篇
  1983年   34784篇
  1982年   20863篇
  1979年   37553篇
  1978年   27224篇
  1977年   22466篇
  1976年   21547篇
  1975年   22591篇
  1974年   27611篇
  1973年   27200篇
  1972年   25370篇
  1971年   23729篇
  1970年   22208篇
  1969年   20614篇
  1968年   19441篇
排序方式: 共有10000条查询结果,搜索用时 603 毫秒
941.
SUMMARY Current standard specifications for the laboratory evaluation of denture base materials require subjective assessment of colour stability. This study evaluates a new objective measurement technique for translucent denture base materials, by comparing quantitative data with the results obtained from a standard subjective method. Preliminary work on three representative commercial acrylic materials resulted in the selection of a white background for the quantification of colour change of these translucent materials. One half of each sample was exposed to artificial sunlight for 24 h.
The colour of both exposed and unexposed resin was measured on the CIE L*a*b* scale using a photoelectric colorimeter. Significant changes in the b* and E* values (P < 0.001) were observed following light exposure. Objective data for a wide range of commercial materials were compared with the results of a subjective evaluation and it was shown that a change in b* of 1.5 units was discernable subjectively by eye for 100% of the cases. It is suggested that this method and limit value could form the basis of a new objective colour change specification for polymeric dental materials.  相似文献   
942.
In order to satisfy the need to restore the aesthetics, phonetics and comfort and to facilitate optimal hygiene procedures, 20 edentulous patients were treated with a new concept of overdenture therapy on implants ad modum Brånemark. After 24±3.5 months the patients were re‐examined. They were asked to answer a questionnaire and use a Visual Analogue Scale (VAS) to give their opinion on the prosthetic treatment. The results indicate that an implant‐retained overdenture in the maxilla with this design can satisfy the patients needs in aesthetics, phonetics and comfort and can 1 facilitate oral hygiene measures.  相似文献   
943.
Summary Two cases of documented HIV-1 transmission by needle stick and one case of probable transmission by eczematous lesion in three nurses in Germany are reported in the period 1988 to 1991. In two of the cases the nurse knew of the AIDS status of the index patient. A review of the three cases reiterates the importance of repeated training on the prevention of accident and on measures to be taken after an accident, as well as the need to keep the workplace free of additional burden when AIDS or HIV-infected patients are treated.
HIV-Übertragung durch Nadelstichverletzung und über offenes Ekzem. Drei Fälle aus Deutschland
Zusammenfassung Zwei dokumentierte HIV-Übertragungen über Nadelstichverletzung und eine Übertragung über ein offenes Hautekzem der Hand bei zwei Krankenschwestern und einem Pfleger aus den Jahren 1988 bis 1991 werden geschildert. Diese Übersicht der drei Fälle weist auf die Bedeutung von wiederholten Übungen hin, um einen Unfall zu verhüten und auf Maßnahmen die nach einem Unfall zu ergreifen sind. Unter anderem auf die Notwendigkeit den Arbeitsplatz von zusätzlichen Gegenständen freizuhalten, wenn AIDS- oder HIV-infizierte Patienten behandelt werden.
  相似文献   
944.
The objectives of this study were to investigate (1) changes in consumption of alcohol among pregnant women over a period of 5 years (1984/85–1990), (2) changes of attitudes towards drinking during pregnancy in the general population over the same period of time, and (3) possible connections between (1) and (2). The investigation was designed as a cross-sectional study. Our subjects were two representative samples of pregnant women in Oslo, n = 577 and 425, and two representative samples of the Norwegian population, n = 1004 and 1204. The main outcome measures were a self-completed questionnaire for the pregnant women and a personal interview for the general population sample. There was a significant reduction (50% decrease) in alcohol consumption among the second cohort of pregnant women compared with the first. Furthermore, we found an increase during the 5-year period in the number of persons with a restrictive attitude towards alcohol use during pregnancy. There seems to be a connection between these two phenomena, but with our present state of knowledge it is hard to say anything about the causal relationship between them.  相似文献   
945.
The carpal regions of ten cadaver extremities were imaged by CT. The images were combined into a 3-dimensional model of the carpus using a technique based on a dynamic programming algorithm to find an optimal estimate of the location of the bone boundaries in the CT images. The resulting set of surface points on each bone was used to compute volumes and principal and antipodal axes for the bones. A spatial coordinate system was established based on the positions of the centroids of three bones in the distal carpal row. The angular orientations of all carpal bones were determined with respect to this system. The principal axes for the same bone among ten wrist specimens proved to be more widely dispersed than the antipodal axes for the same bones. The antipodal axes also correspond more closely to an intuitive notion of the “longest axis” of the bones. We conclude that the antipodal axis is a more reliable and useful measure of bone orientation than the principal axis.  相似文献   
946.
Results of arthroscopic acromioplasty related to rotator cuff lesions   总被引:1,自引:1,他引:0  
Summary Seventy-nine patients with a history of the subacromial impingement syndrome were treated by arthroscopic acromioplasty. The results were evaluated with a new scoring system designed to assess subjective symptoms before and after operation. The outcome was related to the pathological lesions of the rotator cuff seen at arthroscopy and graded by our modification of the Neer classification. The overall results were satisfactory in 67%, with men having better results than women. Those with a history of injury did better than those without, and the results in those with partial or total cuff tears were better than those with intact cuffs. Since the state of the cuff affects the result, arthroscopy should precede acromioplasty.
Résumé Soixante dix-neuf patients, présentant depuis 3.5 ans (±1.8) un syndrome de conflit sousacromial, ont été traités par acromioplastie arthroscopique. Les résultats ont été évalués au moyen d'une nouvelle cotation, mesurant la symptomatologie subjective avant et 17 mois en moyenne après l'intervention chirurgicale. On a étudié le rapport entre ces résultats et la morphologie pathologique de la coiffe des rotateurs, constatée lors de l'arthroscopie et classée conformément à notre version modifiée, décrite précédemment, de la classification de Neer. Les résultats globaux étaient satisfaisants dans 67% des cas. Les résultats étaient nettement meilleurs chez les hommes que chez les femmes. Ils étaient significativement meilleurs chez les patients pour qui la symptomatologie était apparue après un traumatisme violent, de même lorsqu'il existait une rupture totale ou partielle de la coiffe des rotateurs. L'état de la coiffe influence les résultats de l'acromioplastie, pour pouvoir le déterminer il faut pratiquer une arthroscopie préalable.
  相似文献   
947.
The synopsis of neurogenic lower urinary tract dysfunctions aims to be practical and tries to give some simple algorithms to the physician to help his understanding of the pathophysiology and to guide him towards an easy, functional, preventive and chronological exploration and treatment.  相似文献   
948.
A study was carried out in order to document any abnormalities in the electro-encephalogram (EEG) that might appear in young adolescents who have deliberately inhaled the range of volatile substances loosely referred to as 'glue'. The EEGs of a group of 'street children' being assisted in a Johannesburg shelter were examined. The records were analysed for any clinical abnormalities and also subjected to spectral analysis in order to examine the overall characteristics of frequency, power and spatial distribution. The EEGs clearly revealed that, although at the time of the examination the subjects were ostensibly abstinent, both clinical and normative evidence of continuing brain disturbance was present. It was concluded that glue sniffing is likely to have long term electrocerebral sequelae.  相似文献   
949.
The results of the in vitro fertilisation programme at Tygerberg Hospital for the period April 1983 to January 1988 are presented. Of the 1117 laparoscopies performed, 825 patients reached the transfer stage. A live-birth rate of 9.3% was achieved. The pregnancy rate after transfer of 4 embryos was 25.9% compared with 15.4% after 2 embryos and 10.8% after 3 embryos (P = less than 0.0001). The multiple pregnancy rate was 2.8% in the group receiving 2 embryos and 11.7% and 10.4% in those receiving 3 and 4 embryos, respectively. Of the 77 successful pregnancies (90 babies), 1 baby died at 34 weeks' gestation as the result of abruptio placentae due to preeclampsia and 1 cot death occurred. The only congenital abnormality encountered was a cleft palate.  相似文献   
950.
Nine hundred and three patients undergoing diagnostic peritoneal lavage (DPL) over a 6-year period were retrospectively reviewed to evaluate the utility of the white blood cell (WBC) count in the lavage fluid. Eleven patients (1.2%) had dialysate WBC counts greater than 500/mm3, with erythrocyte counts less than 10(5)/mm3. Nine of these patients who were lavaged within 4 hours of injury had no intra-abdominal pathology. Two patients, lavaged after 4 hours, demonstrated intra-abdominal injury. Two hundred twenty-three patients (24.7%) had grossly clear dialysate which was not sent for laboratory analysis. None of these patients required laparotomy. We conclude that the WBC count in DPL fluid is of no diagnostic value in victims of blunt abdominal trauma who are lavaged within 4 hours of injury. In addition, laboratory analysis of clear dialysate is not required in these patients.  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