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   420929篇
  免费   18796篇
  国内免费   1130篇
耳鼻咽喉   3884篇
儿科学   12985篇
妇产科学   7512篇
基础医学   48774篇
口腔科学   6192篇
临床医学   37103篇
内科学   82997篇
皮肤病学   4043篇
神经病学   40002篇
特种医学   17091篇
外国民族医学   11篇
外科学   66249篇
综合类   5767篇
一般理论   318篇
预防医学   38719篇
眼科学   9246篇
药学   26119篇
  6篇
中国医学   985篇
肿瘤学   32852篇
  2023年   1345篇
  2022年   2423篇
  2021年   5468篇
  2020年   3278篇
  2019年   5329篇
  2018年   27045篇
  2017年   21188篇
  2016年   23659篇
  2015年   6702篇
  2014年   9347篇
  2013年   12526篇
  2012年   24661篇
  2011年   39093篇
  2010年   28488篇
  2009年   20524篇
  2008年   35230篇
  2007年   38282篇
  2006年   17803篇
  2005年   19323篇
  2004年   19425篇
  2003年   19243篇
  2002年   16458篇
  2001年   2389篇
  2000年   2032篇
  1999年   2503篇
  1998年   3262篇
  1997年   2759篇
  1996年   2276篇
  1995年   2195篇
  1994年   1847篇
  1993年   1636篇
  1992年   1317篇
  1991年   1244篇
  1990年   1140篇
  1989年   1068篇
  1988年   1026篇
  1987年   1001篇
  1986年   995篇
  1985年   1007篇
  1984年   1258篇
  1983年   1156篇
  1982年   1399篇
  1981年   1334篇
  1980年   1200篇
  1979年   725篇
  1978年   776篇
  1977年   644篇
  1976年   602篇
  1975年   484篇
  1974年   504篇
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
991.
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   
992.
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   
993.
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   
994.
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.
Questions addressed in this in-vitro study are (1) what are the actual three-dimensional kinematics of talus and calcaneus during an anterior drawer test as performed with the quasi-static anterior ankle tester (QAAT) (2) does laxity measurement with the QAAT represent the true anterior translation of talus relative to the tibia?. Simultaneous measurements were made with the QAAT and a three-dimensional kinematics analysis system in five specimens. The three-dimensional translations and rotations on three axes were analysed at 25, 50 and 100 N of applied anterior load, with increased ligament damage. For four out of five remaining specimens, anterior translation values of talus and calcaneus and values as measured with the QAAT show a significant increase with growing ligament damage and with higher loads. Skeletal motions of talus and calcaneus show great similarity in three different motion axes, with increased ligament damage and at any given load. Skeletal translations and rotations of talus and calcaneus show great similarity during an anterior drawer movement of the ankle joint. Anterior skeletal translation of the talus and calcaneus show fair correlation with the anterior displacements measurements of the QAAT. These QAAT measurements show an overestimation of the laxity value by more than 200% irrespective of the load applied.  相似文献   
999.
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   
1000.
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