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   1630篇
  免费   188篇
  国内免费   49篇
耳鼻咽喉   25篇
儿科学   114篇
妇产科学   19篇
基础医学   155篇
口腔科学   60篇
临床医学   154篇
内科学   389篇
皮肤病学   31篇
神经病学   117篇
特种医学   194篇
外科学   149篇
综合类   115篇
预防医学   158篇
眼科学   10篇
药学   87篇
中国医学   3篇
肿瘤学   87篇
  2023年   22篇
  2022年   14篇
  2021年   33篇
  2020年   28篇
  2019年   15篇
  2018年   26篇
  2017年   47篇
  2016年   49篇
  2015年   39篇
  2014年   69篇
  2013年   85篇
  2012年   51篇
  2011年   48篇
  2010年   70篇
  2009年   76篇
  2008年   46篇
  2007年   76篇
  2006年   48篇
  2005年   40篇
  2004年   44篇
  2003年   26篇
  2002年   35篇
  2001年   50篇
  2000年   33篇
  1999年   43篇
  1998年   83篇
  1997年   69篇
  1996年   65篇
  1995年   52篇
  1994年   53篇
  1993年   50篇
  1992年   30篇
  1991年   21篇
  1990年   33篇
  1989年   29篇
  1988年   29篇
  1987年   17篇
  1986年   25篇
  1985年   24篇
  1984年   12篇
  1983年   20篇
  1982年   11篇
  1980年   10篇
  1979年   10篇
  1978年   8篇
  1977年   5篇
  1976年   16篇
  1975年   15篇
  1933年   6篇
  1932年   6篇
排序方式: 共有1867条查询结果,搜索用时 0 毫秒
91.
An early onset of delinquency prior to age 13 years increases the risk of later serious, violent, and chronic offending by a factor of 2-3. Also child delinquents, compared to juveniles who start offending at a later age, tend to have longer delinquent careers. This article summarizes the report of the Office of Juvenile Justice and Delinquency Prevention's Study Group on Very Young Offenders, chaired by Rolf Loeber and David P. Farrington. The Study Group, consisting of 16 scholars and 23 coauthors, worked for 2 years on preparing a report, undertaking extensive secondary data analyses, and writing chapters in different speciality areas. The report consists of a state of the art review of the developmental background of child delinquents. The report also summarizes risk and protective factors in the individual, family, peer group, school, and neighborhood that affect that development. Lastly, the report renews relevant preventive and remedial interventions in the juvenile justice system, families, peer groups, schools. and neighborhoods, and makes a case for improvement in the integration of services for child delinquents. Policy recommendations are presented to improve methods of dealing with child delinquents by juvenile justice, child welfare, and mental health agencies.  相似文献   
92.
93.

Background  

Despite extensive research, the five-year survival rate of oral squamous cell carcinoma (OSCC) patients has not improved. Effective treatment of OSCC requires the identification of molecular targets and signaling pathways to design appropriate therapeutic strategies. Several genes from the mTOR signaling pathway are known to be dysregulated in a wide spectrum of cancers. However, not much is known about the involvement of this pathway in tumorigenesis of OSCC. We therefore investigated the role of the tumor suppressor genes, TSC1 and TSC2, and other members of this pathway in tumorigenesis of OSCC.  相似文献   
94.
95.
Nasopharyngeal carriage of Haemophilus influenzae and Streptococcus pneumoniae was studied in 621 healthy Chinese children and 300 healthy Vietnamese children aged from 2 months to 5 years in Hong Kong. The carriage rate of H, influenzae type b in Vietnamese children was 1.3% (CI 0.04-2.63%); it was zero in Chinese. The carriage rate of non-typable H. influenzae was 5.8% (CI 1.4-7.6%) in Chinese and 65.4% (CI 58.9-69.8%) in Vietnamese. The carriage rates of S. pneumoniae were 10.8% (CI 8.3-13.2%) and 55.7% (CI 50.1-61.3%) in Chinese and Vietnamese children, respectively. Univariate and multivariate logistic regression analyses were performed to search for factors associated with differences in carriage rates of both H. influenzae and S. pneumoniae between Chinese and Vietnamese children. Although older age, smaller living area and parental smoking were associated with higher carriage rates, these could not explain the remarkably low carriage rates of both bacteria in Chinese children.  相似文献   
96.
Fragile X syndrome is the most common inherited cause of mental retardation. Early diagnosis is important not only for appropriate management of individuals but also to identify carriers who are unaware of their high risk of having an affected child. The disorder is associated with a cytogenetically visible fragile site (FRAXA) at Xq27.3, caused by amplification of a (CGG)n repeat sequence within the gene at this locus designated FMR1. Clinical and molecular studies have been undertaken to screen for fragile X syndrome in 154 children with moderate and severe learning difficulties of previously unknown origin. Southern blot analysis of peripheral blood showed the characteristic abnormally large (CGG)n repeat sequence associated with fragile X syndrome in four of the 154 children. The findings were confirmed by cytogenetic observation of the fragile site and by further molecular studies. The families of the affected children were offered genetic counselling and DNA tests to determine their carrier status. These findings show that there are still unrecognised cases of fragile X syndrome. Given the difficulty of making a clinical diagnosis and the implications for families when the diagnosis is missed, screening in high risk populations may be justified. The issues involved in screening all children in special schools for fragile X syndrome are discussed.  相似文献   
97.
Growth, puberty and obesity after treatment for leukaemia   总被引:1,自引:0,他引:1  
Final height, body proportions, pubertal growth and body mass index were studied retrospectively in 142 survivors of acute lymphoblastic leukaemia (ALL). Treatment consisted of combination chemotherapy and cranial irradiation (18 or 24 Gy). Significant standing height loss and disproportion, with a relatively short back, was seen in both radiation dose groups. Girls were more severely affected than boys. Pubertal growth was adversely affected, with a reduction in peak height velocity in both sexes. Puberty occurred early in girls but at the normal time in boys. Nearly half the group were obese at final height, with no significant difference in incidence between the sexes. The relative roles of cranial irradiation and chemotherapy in the disturbance of growth, puberty and body composition observed in survivors of childhood ALL remain unclear. The aetiology is almost certainly multifactorial, with radiation-induced growth hormone insufficiency, early puberty, steroids and chemotherapy all having a role.  相似文献   
98.
A cross sectional study assessed the bone mineral density (BMD) of 20 young adult patients who received a renal transplantation in childhood. The BMD of the lumbar spine, mainly trabecular bone, and of the total body, mainly cortical bone, were measured and expressed as an SD score. Fourteen patients (70%) had a BMD SD score of the lumbar spine below -1, of whom six patients were below -2. Fifteen patients (75%) had a BMD SD score of the total body below -1, of whom seven patients were below -2, Both trabecular and cortical bone appeared to be involved in the osteopenic process. The cumulative dose of prednisone was inversely correlated to both lumbar spine and total body BMD SD score. In a multiple regression analysis the cumulative dose of prednisone appeared to be the only factor with a significant effect on BMD SD score. Most young adult patients who had received a renal transplantation in childhood had moderate to severe osteopenia. Corticosteroid treatment played a major part in the development of osteopenia in these patients.  相似文献   
99.
100.
Nursing staff workload may influence hospital-acquired staphylococcal transmission. Closure of wards to new admissions is used in some institutions as part of methicillin-resistant Staphylococcus aureus (MRSA) outbreak control, and we postulated that it worked by reducing staff workload, allowing more time for good infection control practices. We have used the GRASPCopyright workload system to compare nursing workload during six MRSA outbreaks. Two outbreaks occurred while an aggressive control policy ('old'; 1994-1995) was in place, with a low threshold for ward closure. Control measures had been relaxed before the later four outbreaks, with wards remaining fully or partially open unless MRSA transmission proved intractable ('new'; 1995-1996). To standardize the analysis we compared GRASP and epidemiological data for periods while MRSA transmission was occurring on each ward ('during'), and four week periods 'before' and 'after'. Closing wards to admissions reduces staff workload towards a quality environment, although the nursing requirements of remaining patient rises. Workload pressures may rise during outbreaks if wards are not closed quickly and fully, and patients are not transferred to specialist isolation facilities. Changes in nursing workload need to be assessed during comparative studies of outbreak control measures and the GRASP(c) system appears to be a sensitive way to measure these.  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