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   4183篇
  免费   140篇
  国内免费   92篇
耳鼻咽喉   4篇
儿科学   20篇
妇产科学   8篇
基础医学   792篇
口腔科学   23篇
临床医学   111篇
内科学   264篇
皮肤病学   48篇
神经病学   85篇
特种医学   124篇
外科学   66篇
综合类   202篇
预防医学   2427篇
眼科学   4篇
药学   127篇
中国医学   15篇
肿瘤学   95篇
  2023年   21篇
  2022年   16篇
  2021年   27篇
  2020年   66篇
  2019年   55篇
  2018年   41篇
  2017年   42篇
  2016年   53篇
  2015年   66篇
  2014年   44篇
  2013年   77篇
  2012年   75篇
  2011年   93篇
  2010年   100篇
  2009年   195篇
  2008年   198篇
  2007年   223篇
  2006年   186篇
  2005年   111篇
  2004年   107篇
  2003年   125篇
  2002年   155篇
  2001年   220篇
  2000年   188篇
  1999年   158篇
  1998年   67篇
  1997年   109篇
  1996年   104篇
  1995年   91篇
  1994年   93篇
  1993年   50篇
  1992年   77篇
  1991年   58篇
  1990年   73篇
  1989年   65篇
  1988年   90篇
  1987年   68篇
  1986年   79篇
  1985年   55篇
  1984年   64篇
  1983年   55篇
  1982年   55篇
  1981年   56篇
  1980年   54篇
  1979年   49篇
  1978年   55篇
  1977年   72篇
  1976年   112篇
  1975年   68篇
  1974年   53篇
排序方式: 共有4415条查询结果,搜索用时 250 毫秒
61.
An investigation was undertaken to determine the factors influencing performance of medical students at the Faculty of Medicine, University of Kuwait. Data were collected for the first batch of 42 candidates who successfully passed the 7-year medical programme. Results showed high correlations between high-school admission grades and subsequent performance during the medical programme. Similar results were also obtained with English proficiency. A partial correlation controlling for English proficiency, however, showed a systematic decline in the magnitude of the correlations between high-school grades and performance during the medical programme. In fact the relationship between high-school GPA and clinical GPA was non-significant. A prominent influence of English proficiency on performance is indicated.  相似文献   
62.
The emphasis on academic achievement in medical student selection has given rise to the fear that students entering medicine may comprise a homogeneous group with tendencies towards academic and scientific pursuits rather than humanistic and person-oriented health care. The Attitudes to Social Issues in Medicine (ATSIM) scale was administered to first-year Australian medical students and first-year students in other faculties including students with significantly lower academic performance measured by high school examination scores. The medical student group was found to be less conservative towards general social issues than students enrolled in commerce and science faculties and scored equally with arts students. Greater conservatism was, however, apparent in those areas which most closely affect the doctor's role. Medical students were less positive than other student groups in their attitudes towards increased government control of the medical profession, the contribution of allied health professionals and the importance of social aspects of illness. On attitudes to issues such as prevention and doctor-patient relationships which do not challenge the knowledge base or traditional role and status of the medical profession, however, medical students demonstrate equal or greater concern compared with other student groups.  相似文献   
63.
Vocational training is a key element of professional development in general practice. Learner-centred approaches to teaching bring a need for greater understanding of the individual learning styles and preferences of trainees. This paper reports the findings of a pilot study undertaken to determine factors that may influence learning among general practice trainees. A questionnaire survey of 261 trainees in six regions in the UK was carried out to explore attitudes to a series of themes identified in semi-structured interviews with trainees at the end of their training. Six distinct subscales were identified using principal components analysis. These are named 'Learning from Patients', 'Openness to Criticism', 'Negative Attitudes', 'Desire for Clear Guidelines', 'Peer Support', and 'Academic Approach'. Males scored significantly higher on 'Academic Approach' (   P < 0.05  ). Each of the subscales reflects themes that permeate the atmosphere of general pratice training. Further work is required to establish relationships between the subscales and the outcomes of learning and to explore the implications for continuing professional development. The questionnaire is an instrument that may prove useful in the future investigation of learning in general practice.  相似文献   
64.
The development of molecular techniques for HLA typing has allowed the identification of genes previously assigned as serologic blank alleles. Lack or poor cell surface expression has been found for molecules coded by HLA-A, -B, -DRB4, -DRB5, and -DPB1 genes. In this report we describe the first HLA-C gene encoding for a null cell surface molecule. HLA-Cw*0409 N shows a point deletion at position 1095 within exon 7. This mutation provokes a codon reading shift, generating a new translation stop codon 97 bp downstream to that described in alleles normally expressed. This new stop codon location implies the presence of 32 extra amino acid residues in the cytoplasmic domain. Transfection experiments suggest that elongation of the cytoplasmic domain in Cw*0409 N would be the cause of cell surface expression failure, although Cw*0409 N heavy chain is able to create stable complexes with beta2-microglobulin. HLA-C fragment length analysis in a small selected group of samples with B44-Cblk haplotypic associations allowed us to identify two additional subjects showing both a serologic silent Cw*04 allele and a point base deletion at the 3' end of the HLA-C gene. This finding indicates that the allele frequency of Cw*0409 N within serologic C blank alleles would be appreciable, although basically restricted to the (A23)-Cw*0409 N-B*4403-DR7-DQ2 haplotype.  相似文献   
65.
目的通过对CT抗原(cancer-testis antigen)KM-HN-1进行HLA-A*0201限制性表位预测,并对候选表位肽与HLA-A*0201分子结合亲和力及复合物稳定性进行分析,为探索基于KM-HN-1的免疫治疗奠定基础。方法利用基于蛋白酶体剪切位点特异性的算法PAProc及基于肽MHC-I结合的算法BIMAS和SYFPEITHI对KM-HN-1进行HLA-A*0201限制性表位预测.合成KM-HN-1相关候选表位肽KM-HN-I321-329(KLLPFRETV),KM-HN-I303-211,(FLPTAPPNV),KM-HN-I629-637。(TLLQIIETV),KM-HN-I87-95(ILNKSIIEV),KM-HN-I538-596。(QMMEALDQL)及阳性对照肽HBVcAg18-27(FLPSDFFPSV);对这些合成肽与HIA-A*0201分子结合亲和力及其复合物稳定性根据文献报道的方法进行分析。结果KM-HN-I321-329(KLLPERETV)结合亲和力最低,KM-HN—I203-211(FLPTAPPNV)结合亲和力最高,其余3条肽结合亲和力介于2者之间;稳定性实验(DC50)结果显示:KM-HN-I538—546(QMMEALDQL)DC50小于2h,KM—HN-I321-329(KLLPERETV)的DC50介于2~4h之间,KM-HN-I87-95。(ILNKSIIEV)的DC50介于6~8h之间,KM-HN-I233-211(HLPTAPPNV)及KM-HN-I629—633(TLLQIIETV)的DC50均大于8h。结论基于蛋白酶体剪切位点特异性的算法及基于肽MHC-I结合的算法对KM-HN-1进行HLA-A*0201限制性表位预测,结合候选表位肽与HLA-A*0201分子结合的亲和力与复合物稳定性实验分析,为该抗原HLA-A*0201限制性表位的鉴定奠定了基础。  相似文献   
66.
目的 鉴定一个人类白细胞抗原(human leukocyte antigen,HLA)新等位基因HLA-B*4609.方法 使用序列特异性寡核苷酸PCR技术进行HLA基因分型,发现反应格局异常的可疑新等位基因,应用分子克隆和DNA双向测序技术测定新等位基因的核苷酸序列,并与已知等位基因进行序列比对分析.结果 检出1个样本HLA-B位点反应格局异常,DNA测序分型结果一个为B*151101,另一个的核苷酸序列与已知的HLA等位基因均不同,该基因序列与同源性最高的HLA-B*460101基因序列相比,在第3外显子区域中527位碱基发生A→T突变,导致176位编码氨基酸由谷氨酸(GAG)变成缬氨酸(GTG).结论 样本中含有HLA-B新等位基因序列.该序列申报后,被世界卫生组织HLA因子命名委员会正式命名为HLA-B*4609.  相似文献   
67.
Abstract: Genotyping of the HLA-C locus by PCR-SSP in Behçet's disease patients from southern Spain reveals a statistically significant association with Cw*1602 (OR 20.15, corrected ρ<0.05). This is an uncommon allele absent from the healthy control group, which seems to confer higher relative risk than B51 in this study (OR 1.85). Stratified frequencies do not show statistically significant differences but suggest that the Cw*1602-B51 haplo-type could be the main HLA marker of Behçet's disease in the analyzed population.  相似文献   
68.
Lv F  Gao J  Lin J  Liu Z  Xu Y  Ren X  Zhang H  Xu A 《Tissue antigens》2004,64(5):619-620
A novel human leukocyte antigen (HLA)-DQB1 allele, DQB1*020102, was detected in a 28-year-old woman of Han ethnic in Guangzhou, China. Compared with HLA-DQB1*020101 and HLA-DQB1*0202, they differed in only one nucleotide at the position 167 (C to T) of exon 2, which was a highly conserved position. This is a synonymous mutation, which does not cause any change in the amino acid sequence of mature protein.  相似文献   
69.
We report a novel DQA1 allele (DQA1*0403N) identified during sequence-based HLA-DQA1 typing of a Kenyan population. The new allele is identical to DQA1*0401 at exon 2 except for a single-nucleotide substitution at codon 53, changing it from lysine to a stop codon (CAA-->TAA). The substitution at codon 53 was confirmed by sequencing two separate polymerase chain reaction products and by sequencing multiple clones obtained following TOPO-TA cloning. The resulting stop codon at position of codon 53 in exon 2 is predicted to produce a non-functional DQA1 alpha-chain. The new allele has been named by the WHO nomenclature committee as DQA1*0403N. This is the first report of a null allele detected in the DQA1 gene.  相似文献   
70.
Identification of a new HLA-B*56 variant, B*5614   总被引:6,自引:0,他引:6  
Yan LX  Zhu FM  Lv QF  Zhang HQ  Zhang W  He J 《Tissue antigens》2005,65(3):278-279
In this report, the novel allele B*5614 is presented. The allele was identified in a Chinese individual by sequence-based typing. HLA-B*5614 differs from B*5608 by a single nucleotide at position 277G-->C in exon 2. This results in an amino acid change from Gly to Arg at codon 93.  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