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   100229篇
  免费   29412篇
  国内免费   1068篇
耳鼻咽喉   2415篇
儿科学   2648篇
妇产科学   2401篇
基础医学   2772篇
口腔科学   5131篇
临床医学   26167篇
内科学   24889篇
皮肤病学   3272篇
神经病学   12445篇
特种医学   3635篇
外科学   18101篇
综合类   168篇
现状与发展   40篇
一般理论   8篇
预防医学   13928篇
眼科学   2327篇
药学   1431篇
中国医学   8篇
肿瘤学   8923篇
  2024年   742篇
  2023年   5060篇
  2022年   1137篇
  2021年   2779篇
  2020年   5350篇
  2019年   2080篇
  2018年   6966篇
  2017年   7356篇
  2016年   7948篇
  2015年   8024篇
  2014年   10466篇
  2013年   12215篇
  2012年   3953篇
  2011年   3810篇
  2010年   6898篇
  2009年   9215篇
  2008年   3660篇
  2007年   2604篇
  2006年   3748篇
  2005年   2309篇
  2004年   1659篇
  2003年   1265篇
  2002年   1171篇
  2001年   1851篇
  2000年   1152篇
  1999年   1708篇
  1998年   2092篇
  1997年   1924篇
  1996年   1960篇
  1995年   1698篇
  1994年   1089篇
  1993年   928篇
  1992年   758篇
  1991年   629篇
  1990年   504篇
  1989年   512篇
  1988年   497篇
  1987年   382篇
  1986年   353篇
  1985年   288篇
  1984年   249篇
  1983年   298篇
  1982年   233篇
  1981年   205篇
  1980年   123篇
  1978年   128篇
  1977年   120篇
  1976年   87篇
  1974年   73篇
  1972年   70篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
Society often expects mothers and fathers to share equally in the perinatal grief process because the child was a common bond between them. Unfortunately, in perinatal grief, this is not always the case. The mother and the father can experience incongruent grieving and use discordant coping mechanisms. It is important to evaluate these differences to facilitate communication between the distraught parents. Improved communication can in turn facilitate the grieving process.  相似文献   
32.
33.
34.
35.
This study evaluates the potential for endothelial seeding of a collagen-impregnated Dacron graft with or without surface modifiers (fibronectin, heparin) to attach and retain these cells during flow. Human umbilical endothelial cells were harvested, cultured, labeled with Indium111-oxine and seeded onto 30 mm X 4 mm diameter grafts. Six graft surfaces were studied: 1) a collagen-impregnated Dacron graft, HemashieldR (C); 2) C + fibronectin (C + F); 3) C + heparin (C + H); 4) C + F + H; 5) HytrelR + F (Hyt + F); and 6) Hyt + F + H. Radioactive loss determined the percentage attachment and then percentage retention of labeled inoculum after a one-hour in vitro perfusion. Scanning electron and light microscopy demonstrated the endothelium on the graft surface following perfusion. Fibronectin-coated grafts had a significantly higher percentage attachment than those without fibronectin (ANOVA, P less than 0.05). However, the percentage retention following perfusion was similar for all Dacron grafts and statistically inferior to the HytrelR grafts studied (ANOVA, P less than 0.05). SEM evaluation of the C + F + H graft surface was qualitatively the most impressive Dacron surface for seeding, yet was inferior to the HytrelR graft. We conclude that fibronectin benefits the initial attachment of endothelium to collagen-coated Dacron rivaling the HytrelR surface. Fibronectin does not improve percentage retention of the HemashieldR surface during perfusion, therefore, some of its initial benefit is lost.  相似文献   
36.
Directors of nursing at 23 nursing homes with Alzheimer's units in Southwestern Pennsylvania completed a self‐reported survey of 12 questions. Responses from the self‐administered questionnaires (100% response rate) revealed a wide variation in the staff categories assessing the oral health status of newly admitted residents with AD. The respondents described oral examinations that were incomplete when compared to the oral indicators listed in the Minimum Data Set. All nursing homes reported that oral hygiene was provided each day. The number of residents in a facility had a significant effect on the frequency of oral hygiene provided. Only 52% of the facilities reported yearly oral examinations for this population. According to the respondents, dental treatment was typically performed on‐site. The oral health care costs were paid by Medicare, Medicaid, the residents/family members, or by other undescribed resources. Insufficient time, staff, and training, as well as uncooperative behavior, were identified as barriers to optimum oral health care for residents with AD. Additional staff, specialized training, and increased government reimbursement were suggested to improve the oral health care for this group of older adults. For future studies, review of medical records and on‐site evaluation of the oral health care at these facilities should be required to verify the reported practices.  相似文献   
37.
38.
39.
40.
Milos Jesenak  MD  PhD    Peter Banovcin  MD  PhD    Zuzana Rennerova  MD  PhD    Lubica Jakusova  MD  PhD    Zuzana Havlicekova  MD  PhD    Vladimir Pohanka  MD  PhD  MPH  FCCP    Maria Pia Villa  MD  PhD    Roberto Ronchetti  MD  PhD 《International journal of dermatology》2009,48(9):941-946
Background  The atopy patch test (APT) is no longer an experimental method; it is increasingly being used as a standard diagnostic tool for the characterization of patients with aeroallergen- and food-triggered disorders. Some technical aspects of this test still remain to be answered. We aimed to study the reproducibility of this test over time in the general child population.
Methods  In a general population of 118 children, we investigated the reproducibility of duplicate APTs with four food allergens in their native form, which were repeated at set intervals from the first test: 7 days (group 1), 14 days (group 2), and 21 days (group 3).
Results  We observed very poor reproducibility on both sides of the back in all three studied subgroups. The reproducibility rates and Cohen's κ values did not improve when we did not consider the side of the back. There were no differences in the prevalence of atopy between the subjects with reproducible and nonreproducible APT results. All three groups studied showed no difference in the prevalence rates of atopy. There was no relationship between APT and skin prick test positivity for the same allergen. Questionnaire-derived data about previous food-related reactions did not help in the evaluation of the doubtful nonreproducible APT results with food allergens.
Conclusions  Our results show that the reproducibility of food APTs is poor and unsatisfactory over time, and there is an urgent need for the development of optimal, stable, and good-quality APT testing substances.  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