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   251064篇
  免费   18392篇
  国内免费   1128篇
耳鼻咽喉   2786篇
儿科学   6492篇
妇产科学   4591篇
基础医学   32945篇
口腔科学   4574篇
临床医学   25257篇
内科学   53362篇
皮肤病学   3391篇
神经病学   24300篇
特种医学   8396篇
外国民族医学   11篇
外科学   38478篇
综合类   3467篇
一般理论   318篇
预防医学   21302篇
眼科学   6544篇
药学   16964篇
  4篇
中国医学   361篇
肿瘤学   17041篇
  2023年   1209篇
  2022年   1813篇
  2021年   5435篇
  2020年   3263篇
  2019年   5301篇
  2018年   5957篇
  2017年   4472篇
  2016年   4963篇
  2015年   5832篇
  2014年   8610篇
  2013年   11802篇
  2012年   18022篇
  2011年   18918篇
  2010年   10584篇
  2009年   9433篇
  2008年   16604篇
  2007年   17461篇
  2006年   17306篇
  2005年   17281篇
  2004年   16193篇
  2003年   15050篇
  2002年   14066篇
  2001年   2116篇
  2000年   1615篇
  1999年   2331篇
  1998年   3074篇
  1997年   2569篇
  1996年   2189篇
  1995年   2102篇
  1994年   1749篇
  1993年   1579篇
  1992年   1270篇
  1991年   1158篇
  1990年   1008篇
  1989年   982篇
  1988年   971篇
  1987年   952篇
  1986年   962篇
  1985年   977篇
  1984年   1225篇
  1983年   1129篇
  1982年   1368篇
  1981年   1315篇
  1980年   1152篇
  1979年   708篇
  1978年   751篇
  1977年   636篇
  1976年   587篇
  1975年   471篇
  1974年   476篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
992.
Background. Keratinizing odontogenic cysts of the mandible commonly have an aggressive clinical course, marked by multiple recurrences. Primary intraosseus carcinoma (PIOC) of the mandible is rare, and when it occurs it is often found to be arising in or closely associated with some type of cystic structure. Methods. A patient with squamous cell carcinoma arising from an odontogenic keratocyst is studied clinically, radiographically, and pathologically. Results. The patient who was documented to have an odontogenic keratocyst, 1 year later had a squamous carcinoma removed from the recurrent cyst. Conclusion. We report the occurrence of squamous cell carcinoma arising from a recurrent odontogenic keratocyst, which has not previously been documented in the literature. The literature on this subject is reviewed. © 1994 John Wiley & Sons, Inc.  相似文献   
993.
We investigated the natural history of atopic dermatitis (AD) in a population-based birth cohort and assessed whether children at risk of visible eczema at 5 years of age can be identified from total immunoglobulin E (IgE) levels measured at 8, 12 and 18 months. AD data collected included a whole body examination for visible eczema at 49 months (4 years) and 61 months (5 years) of age and parent completed questionnaire data throughout their early lives. Children were divided into four groups based on their natural history of early AD: persistent (AD at 1, 6, 18, 30 and 42 months, n  = 34), intermittent early onset (before 18  months of age, n  = 495), intermittent late onset (18–42 months of age, n  = 273) and unaffected ( n  = 429). Visible eczema at 5 years of age was present in 12.2% (117/957) (95% confidence interval [CI] 10.1–14.3%) of the children. Levels of total IgE at 8, 12 and 18 months of age were associated with early onset of AD, but not with AD of later onset. For all four natural history groups, the geometric mean total IgE at 12 months was higher in those who subsequently had visible eczema than those who did not. However, the degree of overlap was such that total IgE at 12 months of age was a poor predictor of eczema at age five. A cutoff point of 78 kU/l had the highest positive predictive value for visible eczema at 5 years of age of 28.6%, with a sensitivity of 12% and specificity of 95%.  相似文献   
994.
BACKGROUND: Providing patients with an audiotape of their medical consultation has been a relatively common practice in oncology clinics for some years. However, broader generalisability of the technique has yet to be examined. AIMS: To investigate the efficacy of providing patients with an audiotape of their consultation in a general practice setting. DESIGN OF STUDY: Randomised controlled trial: 95 experimental participants, 85 controls. SETTING: Routine surgeries run by two general practitioners (GPs) in two different health centres. METHOD: All patients attending GP appointments were eligible for inclusion. Patients were followed up by telephone 7-10 days later. RESULTS: More than half (61%) of the patients who received a tape listened to it. Among listeners, 64% rated the tape useful or very useful; 24% noticed information not heard in the consultation. Half of listeners (46%) said that their understanding of the consultation improved after listening to the tape. Half of the listeners (48%) shared the tape with others, of whom 71% found sharing helpful or very helpful. However, 21% of those who shared the information with others found this unhelpful or very unhelpful, suggesting that patients may need to be briefed on the potential risks of sharing. At follow-up a week later, it emerged that being given a tape had no effect on adherence with GPs' advice, nor on anxiety about conditions. CONCLUSION: Providing patients with an audiotape of their GP consultation was positively rated by many patients. Although there were no detectable clinical effects at follow-up, the technique merits further evaluation in general practice.  相似文献   
995.
996.
997.
This study evaluated a multiple‐family group‐intervention program (MFGI) for first‐time juvenile offenders. The recidivism rate for subjects who completed the MFGI (the Family Solutions Program) was compared to recidivism rates of two other groups of first‐time juvenile offenders. Using logistic regression analysis predicting who will recidivate, juvenile first offenders who were placed on probation (N = 95) were 9.3 times more likely to re‐offend compared to the Family Solutions Program (FSP) graduates (N = 267). Families referred to FSP but who dropped out (most never attended the 10 session program) (N = 93) also were 4.4 times more likely to re‐offend compared to FSP graduates. An intent‐to‐treat model comparing the combined group of FSP graduates and dropouts with the probation group indicated that a youth in the probation group was 8.1 times more likely to re‐offend than a youth referred to the FSP. Results indicating better outcomes on recidivism for FSP graduates were significant for both male and female youths. Implications for policy and practitioners are discussed. © 2004 Wiley Periodicals, Inc. J Comm Psychol 32: 177–200, 2004.  相似文献   
998.
Introduction In combination with the catalytic domain, the ancillary domains of the ADAMTS' are proposed to regulate activity via interactions with sulfated GAGs, the extracellular matrix (ECM) and cell surface. Interactions with both GAGs and the ECM have been attributed to the thrombospondin (TSP) type 1 motifs and spacer region ( Kuno and Matsushima 1998 ; Flannery et al. 2002 ). ADAMTS‐1, ‐4 and ‐5, all undergo cleavage within their respective spacer regions ( Flannery et al. 2002 ; Rodriguez‐Manzaneque et al. 2000 ; Georgiadis et al. 2002 ), an event which has been reported to increase activity towards the interglobular domain of aggrecan and decrease the heparin affinity of ADAMTS‐4 ( Flannery et al. 2002 ; Gao et al. 2002 ). Materials and methods V5‐ and His‐tagged recombinant human ADAMTS‐4 constructs terminating after the catalytic (?DTS), disintegrin‐like (?TS), TSP (?S) or spacer region (Full) were expressed in High‐Five cells. Proteoglycanase activities of the resultant proteins were assayed with solution digests of aggrecan and a polyacrylamide‐entrapped aggrecan particle assay. Proteolytic activity was measured using a novel, nonglycosylated, reporter substrate assay. Results All forms of ADAMTS‐4 were active to varying degrees in the reporter substrate assay. Digestion of aggrecan in solution digests was apparent in all proteins with the exception of the catalytic domain in isolation (?DTS). Activity towards aggrecan decreased with increasing truncation of the protein. Discussion Removal of the cysteine‐rich‐spacer domain and further C‐terminal truncations decrease the activity of ADAMTS‐4 towards aggrecan, whilst the proteolytic activity remains intact. Cleavages releasing the ancillary domains of ADAMTS' may therefore alter the catalytic activity of these enzymes against proteoglycans and also nonglycosylated polypeptides. More information is required about potential substrates for the processed forms of ADAMTS‐4.  相似文献   
999.
1000.
Objective   To profile the expression of all known members of the matrix metalloproteinase ( MMP ), a disintegrin and metalloproteinase with thrombospondin motifs ( ADAMTS ), and tissue inhibitor of metalloproteinases ( TIMP s) gene families in normal cartilage and that from patients with osteoarthritis (OA).
Methods   Human cartilage was obtained from femoral heads at joint replacement for either osteoarthritis or following fracture to the neck of femur. Total RNA was purified and expression of genes assayed using quantitative real-time PCR.
Results   Several members of the above gene families were regulated in OA. Genes increasing in expression in OA were: at P  < 0.001, MMP-13 , MMP-28 , ADAMTS-16 ; at P  < 0.01, MMP-9 , MMP-16 , ADAMTS-2 , ADAMTS-14 and at P  < 0.05, MMP-2 , TIMP-3 , ADAMTS-12 . Genes decreasing in expression in OA were: at P  < 0.001, MMP-1 , MMP-3 , ADAMTS-1 ; at P  < 0.01, MMP-10 , TIMP-1 , ADAMTS-9 and at P  < 0.05, TIMP-4 , ADAMTS-5 , ADAMTS-15 . Correlation analysis revealed that groups of genes across the gene families are co-expressed in cartilage.
Conclusion   This is the first comprehensive expression profile of all known MMP , ADAMTS and TIMP genes in cartilage. Patterns of expression provide a foundation on which to understand mechanisms of gene regulation in OA and potentially for refining the specificity of anti-proteolytic therapies.  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