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   478篇
  免费   16篇
耳鼻咽喉   6篇
儿科学   10篇
妇产科学   34篇
基础医学   38篇
口腔科学   7篇
临床医学   59篇
内科学   73篇
皮肤病学   28篇
神经病学   27篇
特种医学   4篇
外科学   74篇
综合类   11篇
预防医学   71篇
眼科学   1篇
药学   40篇
肿瘤学   11篇
  2020年   6篇
  2019年   4篇
  2015年   3篇
  2014年   8篇
  2013年   13篇
  2012年   7篇
  2011年   6篇
  2010年   16篇
  2009年   14篇
  2008年   5篇
  2007年   3篇
  2006年   3篇
  2002年   4篇
  2001年   3篇
  1999年   10篇
  1998年   6篇
  1997年   15篇
  1996年   28篇
  1995年   16篇
  1994年   11篇
  1993年   13篇
  1992年   11篇
  1991年   14篇
  1990年   19篇
  1989年   12篇
  1988年   12篇
  1987年   13篇
  1986年   16篇
  1985年   11篇
  1984年   7篇
  1983年   8篇
  1982年   6篇
  1981年   6篇
  1980年   6篇
  1979年   5篇
  1978年   5篇
  1977年   3篇
  1976年   7篇
  1975年   3篇
  1970年   3篇
  1963年   3篇
  1960年   4篇
  1959年   16篇
  1958年   17篇
  1957年   13篇
  1956年   9篇
  1955年   14篇
  1954年   17篇
  1949年   3篇
  1948年   6篇
排序方式: 共有494条查询结果,搜索用时 15 毫秒
1.
2.
Objective To evaluate parents’ fruit and vegetable intake and their use of pressure to eat in child feeding as predictors of their 5-year-old daughters’ fruit and vegetable, micronutrient, and fat intakes.Subjects Data were obtained from 191 non-Hispanic white families with 5-year-old girls.Design Parent data included reports of pressure in child feeding and their own fruit and vegetable intake. Girls’ intakes of fruits and vegetables, selected micronutrients, and fat were the main outcomes of interest.Statistical analysis Structural equation modeling was used to test a model describing relationships among parents’ fruit and vegetable intake, parents’ use of pressure in child feeding, and daughters’ fruit and vegetable, micronutrient, and fat intakes.Results The model provided a good fit to the data, revealing that girls’ fruit and vegetable intake was positively related to their parents’ reported fruit and vegetable intake. Parents who consumed fewer fruits and vegetables tended to report greater pressure in child feeding and had daughters who consumed fewer fruits and vegetables. Girls’ reported fruit and vegetable intakes were positively related to their micronutrient intakes and negatively associated with fat intake.Applications/conclusions This research demonstrates that parents’ own fruit and vegetable intake may encourage fruit and vegetable intake in their daughters, leading to higher micronutrient intakes and lower dietary fat intakes. Conversely, pressure to eat may discourage fruit and vegetable intake among young girls. J Am Diet Assoc. 2002;102:58–64.  相似文献   
3.
4.
5.
6.
Sendai virus (SV), mouse hepatitis virus (MHV), and pneumoniavirus of mice (PVM) are common viral infections of mice. Influenceof these viral infections on the prevalence of liver tumors,lung tumors, and lymphoma is of concern in chemical carcinogenicitystudies. Body weight, survival, and tumor prevalence of B6C3F1mice with and without viral infections in 33 male and 34 femaleuntreated control groups and 32 male and 32 female low- andhigh-dose groups of 2-year chemical carcinogenicity studieswere evaluated. In male mice, the SV infection was associatedwith significantly (p < 0.05) higher survival of control,low-dose, and high-dose groups, and higher prevalence of livertumors and lymphoma. The increases in tumor prevalence are possiblydue to an increase in the survival of male mice that had SVinfection. However, when interlaboratory variability and time-relatedeffects were taken into account, the number of significant effectswas consistent with the expected false-positive rate inherentto the statistical procedures. The MHV and PVM infections didnot cause consistent changes in body weight, survival, and tumorprevalences in the control and chemical treatment groups ofmale mice. Viral infections did not cause consistent increasesor decreases in body weight, survival, or tumor prevalence inthe control and chemical treatment groups of female B6C3F1 mice.  相似文献   
7.
We have examined the frequencies of T gamma delta cells in blood, synovial fluids, and synovial membranes of patients with rheumatoid arthritis (RA) and in blood from age-matched controls. Immunocytochemical and immunohistochemical techniques were used with monoclonal antibodies BB3 and A13 to define a major and minor blood subset of T gamma delta cells respectively. Together, these antibodies identify the majority (if not all) of the peripheral blood T gamma delta cells. Significantly lower levels of T gamma delta cells were found in the blood of RA patients compared with controls, whilst higher but not significant numbers were found in the synovial fluids of paired samples. Scattered T gamma delta cells were found only in some synovial membranes with a distribution similar to the T alpha beta cells. Analysis of the two different T gamma delta-cell subsets indicated a ratio of BB3 to A13 of about 5:1 in control and RA blood. However, this ratio was less than 1:1 in the RA synovial fluids and membranes. The migratory nature of the A13+ cells could account for their predominance in these sites. The possible pathological significance of these cells in the rheumatoid synovial fluid and synovial membranes is discussed.  相似文献   
8.
1. Phosphoglucomutase phenotypes have been studied in several generations of the family of an individual heterozygous at each of the three loci, PGM1, PGM2, and PGM3. 2. PGM1 and PGM2 phenotypes were determined using red cells. Fibroblasts grown in tissue culture were used for PGM3 phenotyping. 3. The family results support the genetical hypothesis based on the analysis of dizygotic twin pairs that the PGM3 isozyme patterns found in the placenta are determined by two alleles, PGM13 and PGM23. 4. Locus PGM3 is not closely linked to locus PGM2 5. The data also support the previous findings that locus PGM1 is not closely linked to PGM2 or PGM3.  相似文献   
9.
10.
  • ? A pilot study of catheterized women was designed to investigate their perceptions of pain and discomfort during the procedure.
  • ? The study aimed to test the feasibility of conducting a larger randomized controlled trial.
  • ? Problems were encountered during the execution of the study, due to the need to conform to established principles in clinical research.
  • ? Restrictions on access to patients impinged upon the opportunity to ‘cast the net wide’ in order to generate meaningful data.
  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