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   1361篇
  免费   188篇
  国内免费   4篇
耳鼻咽喉   16篇
儿科学   53篇
妇产科学   61篇
基础医学   306篇
口腔科学   30篇
临床医学   116篇
内科学   193篇
皮肤病学   22篇
神经病学   81篇
特种医学   195篇
外科学   141篇
综合类   63篇
一般理论   1篇
预防医学   91篇
眼科学   8篇
药学   87篇
中国医学   1篇
肿瘤学   88篇
  2019年   14篇
  2018年   12篇
  2016年   12篇
  2015年   27篇
  2014年   20篇
  2013年   33篇
  2012年   44篇
  2011年   49篇
  2010年   35篇
  2009年   34篇
  2008年   46篇
  2007年   46篇
  2006年   48篇
  2005年   36篇
  2004年   39篇
  2003年   34篇
  2002年   55篇
  2001年   48篇
  2000年   36篇
  1999年   29篇
  1998年   31篇
  1997年   44篇
  1996年   36篇
  1995年   36篇
  1994年   24篇
  1993年   23篇
  1992年   31篇
  1991年   22篇
  1990年   42篇
  1989年   42篇
  1988年   56篇
  1987年   60篇
  1986年   52篇
  1985年   37篇
  1984年   37篇
  1983年   20篇
  1982年   23篇
  1981年   21篇
  1980年   17篇
  1979年   13篇
  1978年   16篇
  1977年   14篇
  1976年   13篇
  1975年   17篇
  1974年   15篇
  1973年   10篇
  1972年   20篇
  1971年   10篇
  1970年   9篇
  1968年   11篇
排序方式: 共有1553条查询结果,搜索用时 15 毫秒
71.
72.
Aim: To investigate mothers’ perceptions of breastfeeding and influences from their social network. Methods: A cross‐sectional survey was carried out in Mangochi district, Malawi where questionnaire data from 157 rural and 192 semi‐urban mother–infant pairs were obtained. Results: The proportion of mothers who thought that exclusive breastfeeding should last for 6 months and those who reported to have actually exclusively breastfed were 40.1% and 7.5% respectively. Of those who reported practising exclusive breastfeeding for 6 months, 77.5% stated that exclusive breastfeeding should last for 6 months. This opinion was independently associated with giving birth in a Baby‐Friendly facility, OR = 5.22; 95% CI (1.92–14.16). Among the mothers who thought that exclusive breastfeeding should last for less than 6 months, 43.9% reported having been influenced in their opinion by health workers. Infant crying was the most common (62.4%) reason for stopping exclusive breastfeeding. Conclusion: The findings illustrate the positive impact health workers can have, as well as the need to raise awareness of the benefits of exclusive breastfeeding among both health workers and mothers. Furthermore, continued counselling of mothers on how to deal with stressful infant behaviour such as crying may assist to prolong exclusive breastfeeding.  相似文献   
73.
Few systemic lymphomas have been reported in children with AIDS. We report a case of disseminated Burkitt's lymphoma with lung involvement occurring in a 33-month-old child with acquired immunodeficiency syndrome. Lymphoid interstitial pneumonia was diagnosed by lung biopsy at 23 months of age, but lymphoma was not diagnosed before autopsy.  相似文献   
74.
75.
A silver colloid technique was applied to 18 colposcopic biopsies of the cervix. These comprised 7 cases of cervical intraepithelial neoplasia I (CIN I), 5 cases of CIN II, and 6 cases of CIN III. The nucleolar organizer regions subsequently visualized (AgNORs) were enumerated using an oil immersion lens. The maximum diameters of the AgNORs and aggregates thereof were measured, by hand, from carefully calibrated monochrome photographs. The mean numbers of AgNORs subsequently identified steadily increased, whereas the mean sizes of AgNORs decreased from CIN I to CIN III. In CIN I the mean AgNOR number was 2.3 (range 1.8-3.4) and the AgNOR mean maximum diameter (Dmax) was 1.28 microns (range 0.75-1.75). In CIN II the mean number was 3.5 (range 3.1-4.6) and the AgNOR Dmax was 0.98 micron (range 0.9-1.18). In CIN III the mean number was 4.7 (range 4.0-6.1) and the Dmax was 0.62 micron (range 0.51-0.9). CIN III could be distinguished from CIN I and CIN II on the basis of AgNOR sizes, and an inverse relationship between AgNOR numbers and sizes was established.  相似文献   
76.
To validate the level of olfactory performance of children, we tested 825 volunteers, aged 4–17 years, with an abbreviated form of our pediatric odorant identification task. The test consisted of sniffing and identifying five odorants (baby powder, bubble gum, candy cane, licorice and peach). Mean olfactory scores increased as a function of age, reaching a plateau of about 94–95% correct at 8 years of age. In general, girls out–performed boys. Physicians require a test instrument such as the one we have devised to allow them to diagnose olfactory dysfunction in children. The present task is particularly applicable in screening large numbers of children in clinics or schools because it can be administered easily and rapidly. Adult subjects with olfactory dysfunction also performed poorly on this odorant identification task designed for children. Therefore, we expect that our odorant identification task will also detect children with severe olfactory dysfunction.  相似文献   
77.
The clinician is almost entirely dependent on the histopathologist to accurately diagnose minor salivary gland tumours, but in some cases the histological interpretation of the specimen is very difficult. Recently it has been demonstrated using immunohistochemical techniques that S-100 protein is present in some salivary gland tissues and its localization has been used as an aid in the differentiation of major salivary gland tumours. To assess its value in the diagnosis of minor salivary gland tumours it was localized in sections from 15 such tumours using both a standard peroxidase-antiperoxidase (PAP) and a newly developed immunogold-silver staining sequence (IGSS) technique. Strong staining for S-100 protein was seen in the nuclei and cytoplasm of the cellular areas and also in the cells in the chondroid and myxoid areas of pleomorphic adenomas. Generally the staining was more intense and widespread with the IGSS method. No staining was observed in any of the other tumour types. We conclude that S-100 protein localization is a valuable aid in the differentiation of minor salivary gland tumours. Furthermore, the IGSS method enables more sensitive 'reading' of the staining reaction.  相似文献   
78.
We discuss the case of a 22-year-old black woman who presented with a mass in the left hypotympanicum. Both the pre- and postoperative diagnosis of the lesion was a glomus tympanicum. Histopathologic examination revealed the "tumor" to be a nodule of extramedullary hematopoiesis. Many sickled erythrocytes were also noted within the lesion. A multilingual literature search (English, French, German, Spanish, Portuguese, Italian, and Russian) failed to reveal a documented case of extramedullary hematopoiesis in the hypotympanicum. We assume that the patient's hemoglobinopathy was the cause of her unusual focus of extramedullary hematopoiesis.  相似文献   
79.
80.
In a prospective survey of infants born in a single maternity unit, asymptomatic faecal colonisation by Clostridium difficile occurred in 31 (47%) of 66 babies who provided a faecal sample during week one of life and at age 14 and 28 days, and in 46 (30.7%) of the total of 150 babies for whom at least one faecal sample was obtained during the month of study. There was no evidence for acquisition of the organism from the mother during delivery and colonisation was unrelated to the means of delivery, infant sex, means of feeding, duration of hospital stay, or antibiotic treatment. New colonisation occurred throughout the month of the study and further evidence for environmental acquisition was obtained by the finding of a similar strain of C difficile in 7 babies from one ward together with positive environmental cultures. Colonisation was frequently transient and occasionally intermittent; most infants kept the same strain during their period of carriage. Twenty two (47.8%) babies colonised by C difficile had low titres of cytopathic faecal toxin but none had symptomatic diarrhoea or features of necrotizing enterocolitis. The in vitro toxigenic potential of 57 toxigenic isolates from 36 babies was low and 12 babies carried non-toxigenic strains. Transient colonisation by C difficile in early life is almost certainly more common than is generally recognized and the neonate provides an important reservoir of potential infection.  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