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   7362篇
  免费   926篇
  国内免费   13篇
耳鼻咽喉   49篇
儿科学   215篇
妇产科学   97篇
基础医学   1395篇
口腔科学   174篇
临床医学   546篇
内科学   1203篇
皮肤病学   25篇
神经病学   403篇
特种医学   255篇
外科学   780篇
综合类   69篇
一般理论   6篇
预防医学   2249篇
眼科学   115篇
药学   384篇
中国医学   1篇
肿瘤学   335篇
  2023年   47篇
  2022年   66篇
  2021年   76篇
  2020年   122篇
  2019年   82篇
  2018年   187篇
  2017年   170篇
  2016年   164篇
  2015年   151篇
  2014年   182篇
  2013年   299篇
  2012年   232篇
  2011年   244篇
  2010年   224篇
  2009年   239篇
  2008年   252篇
  2007年   278篇
  2006年   283篇
  2005年   280篇
  2004年   267篇
  2003年   232篇
  2002年   280篇
  2001年   261篇
  2000年   246篇
  1999年   313篇
  1998年   227篇
  1997年   263篇
  1996年   266篇
  1995年   191篇
  1994年   100篇
  1993年   160篇
  1992年   143篇
  1991年   143篇
  1990年   130篇
  1989年   145篇
  1988年   115篇
  1987年   126篇
  1986年   131篇
  1985年   107篇
  1984年   66篇
  1983年   73篇
  1982年   52篇
  1981年   52篇
  1979年   69篇
  1977年   46篇
  1976年   47篇
  1975年   47篇
  1974年   51篇
  1972年   47篇
  1971年   42篇
排序方式: 共有8301条查询结果,搜索用时 15 毫秒
71.
72.
73.
Radiographs and clinical records of 61 patients with calcaneal fractures were studied. Twenty-one patients had diabetes mellitus, and 40 were nondiabetic. All diabetic patients were insulin dependent for more than 5 years and had clinically evident peripheral neuropathy. Eighteen of the diabetic patients had no history of significant trauma. Fourteen had calcaneal insufficiency avulsion (CIA) fractures limited to the posterior third of the calcaneus. The fracture pattern in this group occurred in the same plane as a fatigue-type calcaneal fracture. Fragments of the posterior tuberosity were usually displaced 10-30 mm and were frequently rotated. The mean time from diagnosis of diabetes mellitus to CIA fracture was 20 years. Fractures in the nondiabetic group and in the three diabetic patients with a history of trauma did not resemble the CIA pattern. In the nondiabetic group, there were no insufficiency fractures; 39 fractures occurred with significant force (eg, motor vehicle accident or fall from height), and 33 had extension to subtalar or calcaneocuboid joints.  相似文献   
74.
Synthesis-modulating dopamine (DA) autoreceptor function was studied in vivo using gamma-butyrolactone (GBL) to block propagation along DA axons. DA synthesis was measured by the accumulation of L-3,4-dihydroxyphenylalanine (L-DOPA) after inhibition of aromatic L-amino acid decarboxylase. GBL treatment markedly increased DOPA accumulation in both the striatum and prefrontal cortex of developing rats. The selective DA partial D1 agonist SKF-38393 inhibited this GBL-induced rise in DA synthesis in both the striatum and prefrontal cortex of 15- and 22-day-old rats, but not in adults. The effects of SKF-38393 in developing rats were mimicked by the non-catechol D1 partial agonist CY-208-243, and were blocked by the D1 antagonist SCH-23390, suggesting receptor mediation. The mixed D2/D3 agonist quinpirole attenuated DA synthesis in striatum of both two-week-old and adult rats, but failed to inhibit the GBL-induced increase in DA synthesis in the developing prefrontal cortex. These findings suggest that synthesis-modulating D1-like receptor function may emerge transiently in the developing mammalian forebrain. In the adult striatum these functions appear to be subsumed by D2-like receptors, whereas all synthesis-modulating DA receptor function in prefrontal cortex appears to be essentially lost with maturation.  相似文献   
75.
All the health visitors in the north of England, and more than half the general practitioners, were sent questionnaires about the primary health care of children. More than 90% of the health visitors responded. Most of them took part in developmental screening and considered it primarily their responsibility; some conducted developmental or well baby clinics with no other professionals present. Clinics run by health authorities often occupied several hours per week, and were more frequently attended by health visitors than clinics run by general practitioners. Almost all the health visitors' remaining time was spent in attached practices, despite the fact that more than half said they had neither office nor clinic space of their own on practice premises. A high proportion of time was spent on clerical work; more help with this could free the health visitor to provide better developmental care for all children.  相似文献   
76.
77.
Transmissible mink encephalopathy.   总被引:2,自引:0,他引:2  
Transmissible mink encephalopathy (TME) is a rare disease of ranch-raised mink caused by exposure to an as yet unidentified contaminated food ingredient in the ration. The clinical and pathological similarities between TME and scrapie, together with the indistinguishable physicochemical characteristics of their transmissible agents, suggest that sheep may be the source of infection. However, experimental testing of oral susceptibility of mink to several different sources of sheep scrapie have been unsuccessful. These results indicate that either the feeding of scrapie-infected sheep tissues to mink is not the cause of TME, or that there exists a strain of sheep scrapie having high mink pathogenicity that remains unknown. Additional sources of sheep scrapie need to be tested in mink, and epidemiological investigations of new incidents of TME need to emphasise obtaining a thorough history of past feeding practices.  相似文献   
78.
79.
Acquired Loss of Red-Cell Wj Antigen in a Patient with Hodgkin''s Disease   总被引:2,自引:0,他引:2  
A patient with Hodgkin's disease became temporarily Wj-negative with alloanti-Wj in his serum. Four human autoantibodies, and 1 of 2 murine monoclonal antibodies, with serological characteristics of anti-Wj were nonreactive with his red cells, confirming that they have anti-Wj specificity. Six siblings of the patient are all Wj-positive. The patient was also temporarily Anton-negative, and cross-testing between Wj and Anton red cells and antisera showed mutual compatibility, indicating that the antigens are the same. The patient and 3 of his 6 siblings are also of the rare Lu: - 13 phenotype, providing the first evidence that this is an inherited characteristic.  相似文献   
80.
Objective To develop and validate a consensus set of retrieval categories for how children remember what they have eaten, and to relate retrieval categories to accuracy of reporting items eaten during school lunch.Design A Delphi technique study was conducted using 10 psychologists. The subject matter consisted of responses transcribed from interviews conducted with 89 randomly selected fourth graders within 90 minutes of eating. Retrieval categories were evaluated for accuracy by comparing students’ self-reported lunch intake with observation.Statistical analyses For round 1, a centroid hierarchical cluster analysis was used to identify common sets of rating pairs to propose categories for reaching consensus. For rounds 2 and 3, percent of agreement was calculated. Accuracy was tabulated across meal items and student use by retrieval category.Results After round 3, we found that 23 “near-consensus”categories were used by at least eight raters. Six categories were used 60% of the time, 4 were used 20% of the time, and 5 were used 15% of the time. Less frequently used categories were combined with similar, more frequently used categories for a total of 16 categories. Students used a large variety of retrieval categories when accurately reporting consumption. Of the 16 categories, 12 were used similarly by both accurate and inaccurate students. Where there were differences in accuracy by retrieval category, the more accurate students used “taste/smell/texture”and “visual”in deference to “order items consumed”and “oral cue still present.”Applications These categories provide insight into the broad range of retrieval categories that children use and provide direction for researchers to design and study specific cues to enhance the accuracy of children's self-reports of diet. J Am Diet Assoc. 1997;97:31–36.  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