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   19432篇
  免费   1991篇
  国内免费   41篇
耳鼻咽喉   265篇
儿科学   721篇
妇产科学   536篇
基础医学   2783篇
口腔科学   597篇
临床医学   2372篇
内科学   3607篇
皮肤病学   336篇
神经病学   1683篇
特种医学   885篇
外科学   2306篇
综合类   507篇
一般理论   9篇
预防医学   2005篇
眼科学   281篇
药学   1526篇
  2篇
中国医学   23篇
肿瘤学   1020篇
  2021年   287篇
  2020年   174篇
  2019年   287篇
  2018年   346篇
  2017年   265篇
  2016年   286篇
  2015年   312篇
  2014年   436篇
  2013年   629篇
  2012年   793篇
  2011年   819篇
  2010年   534篇
  2009年   453篇
  2008年   836篇
  2007年   836篇
  2006年   859篇
  2005年   728篇
  2004年   713篇
  2003年   653篇
  2002年   670篇
  2001年   624篇
  2000年   661篇
  1999年   540篇
  1998年   282篇
  1997年   221篇
  1996年   244篇
  1995年   228篇
  1994年   203篇
  1993年   238篇
  1992年   456篇
  1991年   432篇
  1990年   430篇
  1989年   471篇
  1988年   446篇
  1987年   360篇
  1986年   373篇
  1985年   419篇
  1984年   280篇
  1983年   227篇
  1982年   167篇
  1981年   172篇
  1979年   215篇
  1978年   191篇
  1977年   214篇
  1976年   179篇
  1975年   165篇
  1974年   172篇
  1973年   181篇
  1972年   169篇
  1971年   163篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
981.
Functional outcome and provision of care to 82 children (males:females 2.7:1; age range 0 to 16 years) with severe head injury were investigated. The children were admitted to the intensive care units of the Regional Neuroscience Units of the Greater Manchester and Lancashire districts of the North West Region of the UK between 1994 and 1996. A questionnaire was devised based on 12 areas of recovery and data were collected at discharge and 6 weeks, 6 months and 12 months from discharge. Data were collected during home visits and at joint assessment at 12 months with the district consultant community paediatrician (CCP). Early involvement of the CCP enhanced the provision of needs at discharge and 6 weeks after discharge, as did a period of stay in district-level care before discharge home. CCPs received formal notification of the injured child in only 32% of cases by discharge, and 54% of cases by 6 months. Sixty-five per cent of children required early educational support but structured help reached only 55% of these children by the end of the study. Integrated planning between health and education was achieved in about half of the study population. Good physical recovery was achieved by the majority of children but parents said they did not feel prepared for the degree of help which their child still required 12 months after discharge. Children who required anticonvulsants at 12 months' follow-up scored significantly lower on cognitive potential. Psychosocial family functioning deteriorated in a substantial number of families according to parental perception. Prevalence of this perception did not diminish over the study period. Aspects of caregivers' understanding and the child's language deficits, self-care skills, fine and gross motor performance, as well as family, social, and financial consequences were assessed. A dedicated and integrated approach to assessment and provision of care across the domains of hospital, education, and community is discussed.  相似文献   
982.
The cognitive effects of active and sham repetitive transcranial magnetic stimulation (rTMS) were examined in 19 middle-aged and elderly patients with refractory depression. Patients received either active (n = 9) or sham (n = 10) rTMS targeted at the anterior portion of the left middle frontal gyrus. Patients in the active rTMS group improved significantly on a test of cognitive flexibility and conceptual tracking (Trail Making Test-B).  相似文献   
983.
The purpose of this project was to qualitatively explore how identity formation may be affected by the presence of HIV disease. Eight HIV-infected adolescents (three males, five females), aged 17-21, participated in a semi-structured interview that combined measures of identity development with open-ended, qualitative questions aimed at eliciting the adolescents' personal stories and experiences of living with HIV. All participants fell into either Diffusion or Achievement identity statuses, which in turn impacted their response to having HIV. The impact that HIV had on the participants' values and future goals varied across the sample. Findings are discussed in terms of clinical intervention implications, contextual variables, and the need for larger, more comprehensive research efforts.  相似文献   
984.
985.
Background: Population-based studies have identified several clinical variables associated with an increased risk of developing cutaneous melanoma that include phenotype, amount of and response to sun exposure, and family history. However, these observations are of limited relevance to clinical practice as the risk associated with each factor is individually modest and the characteristics of these variables lack precision when applied to a particular individual. Objective: To review the literature regarding recent advances made in the understanding of the genes and genetics of clinical variables associated with an increased risk of melanoma. Conclusion: Variants of the MC1R (melanocortin-1 receptor) have been identified as major determinants of high-risk phenotypes, such as red hair and pale skin, and the ability to tan in response to UV exposure. Several studies also suggest that such variants may increase melanoma risk independent of their contribution to phenotype. A strong genetic basis for both nevus density and size has been demonstrated and the link between nevi and the development of MM has become better defined. Finally, germline defects in several genes involved in cell cycle regulation, namely, p16 and CDK4, have been demonstrated in many familial melanoma kindreds. This progress has introduced the prospect of genetic testing as a means of identifying a limited number of high-risk individuals who can be targeted with regular screening and education regarding UV exposure and skin self-examination. Ultimately, through rational genetic therapy targeted to correcting the underlying molecular defect, altering the natural history of melanoma development may be possible.  相似文献   
986.
987.
Necrolytic migratory erythema (NME), the characteristic rash associated with the glucagonoma syndrome, is a cause of substantial morbidity among patients with this rare malignancy. Treatment options are suboptimal, and often useful for only short or moderate durations. We report the effective, long-term (> 1 year) use of intermittent infusions of amino acids (AA) and fatty acids (FA) administered via peripheral intravenous access for the treatment of NME in the glucagonoma syndrome. Despite resolution of the NME, serum amino acid (initially subnormal) and fatty acid (initially normal) levels remained unchanged. Tumour growth and other symptoms related to the glucagonoma syndrome appear unaffected by such infusions.  相似文献   
988.
989.
OBJECTIVE: Development of an effective HIV vaccine has been limited because of the inherent structural properties of the HIV envelope on native virions and the failure of the immune system to respond in an effective manner. Identification of the interactions of human antibodies with virions resulting in neutralization will facilitate vaccine design. DESIGN: Combinations of human monoclonal antibodies (hMAb) were studied for binding to and neutralization of primary isolate virions. METHODS: Virion binding and neutralization were measured using primary isolate virions. RESULTS: Antibodies and combinations of antibodies to epitopes exposed upon CD4 binding (CD4i) and V3 loop antibodies resulted in additive binding and neutralization of R5X4 virus. Antibodies did not bind to or neutralize R5 virus as well. The combination of V3 loop antibody with 2G12 resulted in enhanced neutralization and binding to the R5X4 isolate but not the R5 isolate. Preincubation of the R5X4 isolate with F240, a non-neutralizing anti-gp41 antibody, significantly enhanced binding and neutralization by CD4i hMAb and 2F5. F240 also enhanced the binding of 2F5 to the R5 isolate and the neutralization of the R5 isolate mediated by 2G12. CONCLUSIONS: Neutralizing epitopes are obscured on intact primary isolate virions and are dynamically exposed upon ligand (CD4) interactions. Interestingly, a non-neutralizing antibody to gp41 also increased binding and neutralizing activity of some hMAb that poorly neutralized R5 virus. These data suggest that non-neutralizing epitopes may be appropriate targets for vaccine design and epitope exposure should be considered in the development of immunotherapeutic strategies for HIV.  相似文献   
990.
OBJECTIVE: To review the effect of calcitonin on bone density and fractures in postmenopausal women. DATA SOURCE: We searched MEDLINE and EMBASE from 1966 to 2000 and examined citations of relevant articles and the proceedings of international osteoporosis meetings. We contacted osteoporosis investigators to identify additional studies and primary authors for unpublished data. STUDY SELECTION: We included 30 studies that randomized women to calcitonin or an alternative (placebo or calcium and/or vitamin D) and measured bone density or fracture incidence for at least 1 yr. DATA EXTRACTION: For each trial, three independent reviewers assessed the methodological quality and abstracted data. DATA SYNTHESIS: Calcitonin reduced the incidence of vertebral fractures, with a pooled relative risk (RR) of 0.46 [95% confidence interval (CI) 0.25-0.87, P = 0.02, n = 1404, 4 trials]. However, the RR from the one relatively large randomized controlled trial (RCT) was 0.79 (95% CI 0.62-1.00, P = 0.05, n = 1108). For nonvertebral fractures, the pooled RR was 0.52 (95% CI 0.22-1.23, P = 0.14, n = 1481, 3 trials). Once again, the single large trial showed a less impressive effect than the smaller trials (RR 0.80, 95% CI 0.59-1.09, P = 0.16, n = 1245). For bone density of the lumbar spine, the pooled weekly dose of 250 to 2800 IU per week resulted in significant increase in the weighted mean difference (WMD) of 3.74 (2.04-5.43, P < 0.01, n = 2260, 24 trials). The combined forearm showed a similar effect, with a WMD of 3.02 (95% CI 0.98-5.07, P < 0.01, n = 468, 9 trials). At the femoral neck, the pooled weighted mean difference showed a nonsignificant trend toward benefit, WMD 3.80 (95% CI -0.32-7.91, P = 0.07, 9 trials, n = 513). Methodologically weaker studies tended to show greater effects on bone density, and the lumbar spine results suggested the possibility of publication bias. CONCLUSIONS: Calcitonin likely increases bone density in postmenopausal women predominantly at the lumbar spine and forearm for weekly doses of greater than 250 IU, although the true effect may be smaller than the pooled estimate would suggest. Calcitonin likely reduces the risk of vertebral fracture; its effect on nonvertebral fracture remains uncertain.  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