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   49113篇
  免费   3299篇
  国内免费   188篇
耳鼻咽喉   532篇
儿科学   1236篇
妇产科学   922篇
基础医学   6455篇
口腔科学   1254篇
临床医学   4771篇
内科学   9970篇
皮肤病学   735篇
神经病学   4806篇
特种医学   2570篇
外国民族医学   6篇
外科学   7239篇
综合类   593篇
一般理论   40篇
预防医学   4025篇
眼科学   1198篇
药学   2951篇
中国医学   75篇
肿瘤学   3222篇
  2023年   185篇
  2022年   294篇
  2021年   811篇
  2020年   617篇
  2019年   822篇
  2018年   965篇
  2017年   781篇
  2016年   923篇
  2015年   1052篇
  2014年   1475篇
  2013年   2056篇
  2012年   3123篇
  2011年   3295篇
  2010年   1873篇
  2009年   1715篇
  2008年   3070篇
  2007年   3161篇
  2006年   3119篇
  2005年   3047篇
  2004年   2858篇
  2003年   2769篇
  2002年   2663篇
  2001年   634篇
  2000年   599篇
  1999年   644篇
  1998年   604篇
  1997年   470篇
  1996年   429篇
  1995年   403篇
  1994年   323篇
  1993年   292篇
  1992年   380篇
  1991年   344篇
  1990年   310篇
  1989年   329篇
  1988年   292篇
  1987年   312篇
  1986年   287篇
  1985年   304篇
  1984年   306篇
  1983年   297篇
  1982年   319篇
  1981年   299篇
  1980年   266篇
  1979年   227篇
  1978年   234篇
  1977年   196篇
  1976年   169篇
  1975年   179篇
  1974年   184篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
81.
An interview study investigating attitudinal and other factors influencing the selection of primary medical care (PMC) agency is described. It focuses on adult patients excluding those with trauma of medical/surgical emergencies and was conducted in part of the Western Region of Melbourne in late 1983, the period immediately prior to the introduction of Medicare. It is based on a cross-sectional survey of in-hours attenders of eight general practices (GP), the Western Region (Community) Health Centre (WRCHC) and the general clinic of the casualty department at the Western General Hospital (WGH). Attenders of these different services differed significantly in their socio-demographic characteristics. WGH attenders were significantly younger and had migrated from non-English speaking countries significantly more often. Male attenders at the WGH had significantly lower socioeconomic status. 71 per cent being not in the workforce. The most commonly stated reasons for attendance at particular services generally were “closeness to home, work”, “recommendation” and “good service”. Reasons given by attenders at the different clinics generally were similar. However GP attenders offered “good service” significantly more often as a reason for choice; WGH attenders offered “cheap/economic reasons” significantly more often and “recommendation” significantly less so. WRCHC attenders offered “workers' compensation” significantly more often. Thirty per cent of attenders overall had attended other than their current clinic during their past three to four illness episodes. While a large majority of patients still attend GP for PMC it is concluded that a pluralist model recognising the legitimacy of different PMC arrangements and multiple use of them by individuals best meets community need. This is likely to be even more true under Medicare. It is concluded that instrumental factors and social networks are important in the selection of PMC, particularly given the limited knowledge of respondents about health services. It is also concluded that cost and economic factors have been given undue weight in selection of primary medical care agency. The use of the WGH casualty department by groups not in the work force, given no real financial advantage in doing so, requires further study.  相似文献   
82.
Variegate porphyria (VP) is an autosomal dominant disorder characterised by a partial defect in the activity of protoporphyrinogen oxidase (PPO), and has recently been genetically linked to the PPO gene on chromosome 1q22-23 (Z=6.62). In this study, we identified a mutation in the PPO gene in a patient with VP and two unaffected family members. The mutation consisted of a previously unreported T to C transition in exon 13 of the PPO gene, resulting in the substitution of a polar serine by a non-polar proline (S450P). This serine residue is evolutionarily highly conserved in man, mouse, and Bacillus subtilis, attesting to the importance of this residue. Interestingly, the gene for Gardner's syndrome (FAP) also segregates in this family, independently of the VP mutation. Gardner's syndrome or familial adenomatous polyposis (FAP) is also an autosomal dominantly inherited genodermatosis, and typically presents with colorectal cancer in early adult life secondary to extensive adenomatous polyps of the colon. The specific gene on chromosome 5 that is the site of the mutation in this disorder is known as APC (adenomatous polyposis coli), and the gene has been genetically linked to the region of 5q22.  相似文献   
83.
We studied the pharmacokinetics of intravenously and orally administered lamivudine at six dose levels ranging from 0.5 to 10 mg/kg of body weight in 52 children with human immunodeficiency virus infection. A two-compartment model with first-order elimination from the central compartment was simultaneously fitted to the serum drug concentration-time data obtained after intravenous and oral administration. The maximal concentration at the end of the 1-h intravenous infusion and the area under the concentration-time curve after oral and intravenous administration increased proportionally with the dose. The mean clearance of lamivudine (± standard deviation) in the children was 0.53 ± 0.19 liter/kg/h (229 ± 77 ml/min/m2 of body surface area), and the mean half-lives at the distribution and elimination phases were 0.23 ± 0.18 and 2.2 ± 2.1 h, respectively. Clearance was age dependent when normalized to body weight but age independent when normalized to body surface area. Lamivudine was rapidly absorbed after oral administration, and 66% ± 25% of the oral dose was absorbed. Serum lamivudine concentrations were maintained above 1 μM for ≥8 h of 24 h on the twice daily oral dosing schedule with doses of ≥2 mg/kg. The cerebrospinal fluid drug concentration measured 2 to 4 h after the dose was 12% (range, 0 to 46%) of the simultaneously measured serum drug concentration. A limited-sampling strategy was developed to estimate the area under the concentration-time curve for concentrations in serum at 2 and 6 h.  相似文献   
84.
Aplastic anaemia is both frequent and difficult to manage in patients with dyskeratosis congenita (DC). We recently treated a 23-year-old male for a year with granulocyte colony-stimulating factor (G-CSF) and erythropoietin (Ep), with an excellent neutrophil response, and a transient effect on haemoglobin levels. G-CSF alone or combined with other cytokines may provide at least a partial effect in pancytopenic patients with DC.  相似文献   
85.
86.
87.
A cDNA encoding a transmembrane 140 kDa isoform of the neural cell adhesion molecule, NCAM, was transfected into the rat glioma cell line BT4Cn. Transfectants with a homogeneously high expression of NCAM-B showed a decreased capacity for penetration of an artificial basement membrane when compared to cells transfected with expression-vector alone or untransfected cells. However, when injected subcutaneously into nude mice, both NCAM expressing cells and control cells produced invasive tumors. Nude mice injected with NCAM positive cells developed tumors with slower growth rates as compared to those induced by NCAM negative cells. This implies that NCAM may not only be involved in adhesive and motile behaviour of glioma cells, but also in their growth regulation.  相似文献   
88.
89.
Cognitive deficits associated with closed head injury (CHI) have been well studied. Less attention has been directed to the emotional consequences of CHI and subsequent attempts to cope with major life events. CHI typically constitutes a catastrophic injury, yet few studies have examined coping strategies used by individuals after CHI or the effects of CHI on family functioning that may mediate coping. Previous workers have speculated that time since injury is a crucial determinant of coping; however, this has not been investigated with regard to CHI. In this preliminary investigation, 40 patients with CHI were compared with 17 neurologically intact controls. The CHI group was divided into two groups according to time since injury. It was found that patients with CHI used information seeking as their most dominant coping strategy regardless of their time since injury. Patients with CHI had higher family cohesion scores than control subjects. Implications of these findings for psychological response to CHI are discussed.  相似文献   
90.
Body pain and treatment response in late-life depression.   总被引:2,自引:0,他引:2  
OBJECTIVE: The authors investigated the influence of body pain on 1) time to treatment response and 2) suicidal ideation, in late-life depression. They hypothesized that higher levels of body pain would predict a longer time to and lower likelihood of response, and increased levels of suicidal ideation. METHODS: Subjects (N=187) were older adult outpatients (age > or =69 years), with current episodes of major depression, who were openly treated with paroxetine up to 40 mg daily and weekly interpersonal psychotherapy. Response was defined as 3 consecutive weeks of Hamilton Rating Scale for Depression at < or =10. Body pain was measured with the Bodily Pain Index of the SF-36 quality-of-life assessment. Authors used survival-analysis models on the responder sample to test the effect of body pain on response, after controlling for severity of depression. RESULTS: Overall response rate was 75.4%. Nonresponders reported more severe pain at baseline. After covarying for severity of baseline depression, no effect was found for physical pain on time-to-response or degree of suicidality. Bodily pain remained stable during acute treatment for responders, independent of depression response to combination psychotherapy and antidepressant treatment. CONCLUSIONS: Older adult patients with higher levels of physical pain can still respond to antidepressant treatment; however, reported bodily pain may be associated with a more difficult-to-treat depression.  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