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   220篇
  免费   8篇
  国内免费   3篇
儿科学   10篇
妇产科学   2篇
基础医学   19篇
口腔科学   11篇
临床医学   14篇
内科学   64篇
皮肤病学   9篇
神经病学   5篇
特种医学   35篇
外科学   16篇
综合类   8篇
预防医学   3篇
眼科学   10篇
药学   6篇
肿瘤学   19篇
  2023年   1篇
  2021年   7篇
  2020年   1篇
  2019年   1篇
  2018年   2篇
  2017年   1篇
  2016年   5篇
  2015年   2篇
  2014年   10篇
  2013年   13篇
  2012年   9篇
  2011年   9篇
  2010年   9篇
  2009年   22篇
  2008年   9篇
  2007年   10篇
  2006年   7篇
  2005年   5篇
  2004年   3篇
  2003年   3篇
  2002年   1篇
  2001年   3篇
  2000年   2篇
  1999年   4篇
  1998年   11篇
  1997年   12篇
  1996年   11篇
  1995年   10篇
  1994年   5篇
  1993年   6篇
  1992年   3篇
  1991年   1篇
  1990年   2篇
  1989年   5篇
  1988年   2篇
  1987年   5篇
  1986年   5篇
  1985年   3篇
  1984年   1篇
  1983年   1篇
  1981年   2篇
  1980年   3篇
  1979年   1篇
  1978年   2篇
  1976年   1篇
排序方式: 共有231条查询结果,搜索用时 15 毫秒
51.
Almaguer‐Mederosa LE, Falcón NS, Almira YR, Zaldivar YG, Almarales DC, Góngora EM, Herrera MP, Batallán KE, Armiñán RR, Manresa MV, Cruz GS, Laffita‐Mesa J, Cyuz TM, Chang V, Auburger G, Gispert S, Pérez LV. Estimation of the age at onset in spinocerebellar ataxia type 2 Cuban patients by survival analysis. Previous studies have investigated the close association that exists between CAG repeat number and the age at onset in SCA2 = spinocerebellar ataxia type 2. These studies have focused on affected individuals. To further characterize this association and estimate the risk of a carrier developing SCA2 at a particular age as a function of a specific CAG repeat size, we have analyzed a large group of 924 individuals, including 394 presymptomatic and 530 affected individuals with a CAG repeat length of 32–79 units. Using a Kaplan–Meier survival analysis, we obtained cumulative probability curves for disease manifestation at a particular age for each CAG repeat length in the 34–45 range. These curves were significantly different (p < 0.001) and showed small overlap. All these information may be very valuable in predictive‐testing programs, in the planning of studies for the identification of other genetic and environmental factors as modifiers of age at onset, and in the design of clinical trials for people at enlarged risk for SCA2.  相似文献   
52.
原发性脾囊肿是一种罕见的疾病,目前尚缺乏对该疾病的理想治疗方法的相关研究.大多数原发性脾囊肿是上皮性囊肿.近几年,腹腔镜脾脏外科手术普及率不断提高.该研究报告了关于经腹腔镜保脾手术治疗脾囊肿的相关经验.1996年至2006年间,作者治疗了11例有症状的非寄生虫性脾脏巨大囊肿病人.病人均诉左上腹涨满症状,触诊可扪及腹部包块.术前腹部超声及CT均已明确诊断.病人接受经腹腔镜脾脏囊肿部分切除术或脾脏囊肿开窗减压术.结果发现,7例病人为脾脏间皮囊肿,2例为脾脏表皮样囊肿,2例为脾脏假性囊肿,没有发现囊肿癌变.手术操作时间为62~85 min,无中转开腹.  相似文献   
53.
Background: Recent studies have shown a substantial decline in caries experience in Australian Army recruits between 1996 and 2002–2003, and in Australian adults between 1987–1988 and 2004–2006. However, studies in children have reported an increasing trend in caries experience between 1998 and 2002. The aim of this study was to investigate caries experience in Australian Army recruits in 2008. Methods: A cross‐sectional study involving 1084 Australian Army recruits was conducted from January to May 2008. Data were obtained from a clinical dental examination with bitewing radiographs, and a questionnaire elicited socio‐demographic data and history on lifetime exposure to fluoridated drinking water. Results: Mean DMFT scores were 3.16, 4.08, 5.16 and 7.11 for recruits aged 17–20, 21–25, 26–30 and 31–35 years, respectively. Recruits with a lifetime exposure to fluoridated drinking water had a mean DMFT of 3.02, while recruits with no exposure had a mean DMFT of 3.87. Conclusions: Caries experience in Australian Army recruits aged 17–25 years increased between 2002–2003 and 2008. Recruits with lifetime exposure to fluoridated drinking water had 25 per cent less caries experience compared with recruits who had no exposure to fluoridated drinking water after adjusting for the effects of age, gender, education and socio‐economic status.  相似文献   
54.
Background Melanoma is a tumour with a very variable progression. Whilst some melanomas grow slowly over many years, others can reach several millimetres in thickness in just a few weeks. Since melanoma is a visible superficial tumour, the information obtained from the clinical interview may be of use to calculate the speed of growth of the melanoma. Objective This study aims to assess the growth rate (GR) of melanomas and the association of this GR with various clinical and pathological factors and their usefulness as prognostic markers for localized invasive cutaneous melanomas. Methods The GR of melanomas was calculated as the ratio of tumour thickness to time of development, as obtained from the clinical history (in millimetres per month). Results Applying the GR calculation to patients with a localized melanoma showed a significant association between melanomas with a GR greater than 0.4 mm per month and an age of 65 years or over, male sex, nodular melanoma, tumour thickness, level of invasion, the presence of ulceration and a high mitotic index. As an independent prognostic factor for overall survival, the GR proved to be significant (P = 0.024). Conclusion The GR of localized cutaneous melanomas may be a possible prognostic factor for survival. Additionally, rapid GR is associated with male patients more advanced in age at diagnosis, which suggests the need to assess new strategies for the early detection of these melanomas.  相似文献   
55.
Background:  Although community water fluoridation has been one of the cornerstone strategies for the prevention and control of dental caries, questions are still raised regarding its cost-effectiveness. This study assessed the impact of changing dental needs on the cost savings from community water fluoridation in Australia.
Methods:  Net costs were estimated as Costs(programme) minus Costs(averted caries). Averted costs were estimated as the product of caries increment in non-fluoridated community, effectiveness of fluoridation and the cost of a carious surface. Modelling considered four age-cohorts: 6–20, 21–45, 46–65 and 66+ years and three time points 1970s, 1980s, and 1990s. Cost of a carious surface was estimated by conventional and complex methods. Real discount rates (4, 7 (base) and 10%) were utilized.
Results:  With base-case assumptions, the average annual cost savings/person, using Australian dollars at the 2005 level, ranged from $56.41 (1970s) to $17.75 (1990s) (conventional method) and from $249.45 (1970s) to $69.86 (1990s) (complex method). Under worst-case assumptions fluoridation remained cost-effective with cost savings ranging from $24.15 (1970s) to $3.87 (1990s) (conventional method) and $107.85 (1970s) and $24.53 (1990s) (complex method). For 66+ years cohort (1990s) fluoridation did not show a cost saving, but costs/person were marginal.
Conclusions:  Community water fluoridation remains a cost-effective preventive measure in Australia.  相似文献   
56.
It has been reported that chloroform administered to BDF1 mice by inhalation for 2 years at concentrations of 5, 30 or 90 p.p.m. for 6 h/day, 5 days/week induced an increase in renal cell tumors in male but not female mice exposed to the doses of 30 and 90 p.p.m. A small increase in liver tumors was statistically significant in the female mice at 90 p.p.m. if the incidences of carcinomas and adenomas were combined. Because chloroform is not a DNA reactive mutagen, a 13-week time-course and dose-response study was conducted under conditions of the original bioassay to examine whether regenerative cell proliferation was an underlying mechanism of carcinogenesis. Mice were given bromodeoxyuridine via infusion during the last 3.5 days prior to necropsy to label cells in S-phase. Chloroform induced pathology and regenerative cell proliferation, measured as the labeling index (LI, percentage of cells in S-phase), were assessed microscopically and immunohistochemically. Male mice exposed to 30 and 90 p.p.m. exhibited a dose-dependent increase in regenerating tubules within the renal cortex and up to a 31-fold increase in LI. No renal lesions or increased LI were observed in females. Increased centrilobular to midzonal hepatocyte degeneration and vacuolation and a 7-fold increase over controls in the hepatocyte LI were observed in the female mice at 90 p.p.m. at 13 weeks. Males exhibited similar pathology, but the increase in LI was not sustained. The observed correlations between cytolethality and regenerative cell proliferation with tumor formation supports extensive evidence that chloroform induces cancer via a non- genotoxic-cytotoxic mode of action. A concentration of 5 p.p.m. is the no-observed-adverse-effect level for nephrotoxicity, cell proliferation and cancer. An appropriate safety factor applied to this value is a straightforward approach to cancer risk assessment that is consistent with the mode of action of chloroform.   相似文献   
57.
In 3646 children with at least one confirmed urinary tract infection the prevalence of vesicoureteric reflux at presentation was correlated with progressive renal damage during follow up of not less than two and up to 16 years. Reflux was not demonstrated either at presentation or at any subsequent time in almost one half of the children who suffered progressive renal damage and was not a risk factor for progressive renal damage in boys under 1 year. It was an important risk factor in boys over 1 year and in girls of any age. The risk of progressive renal damage in children in whom micturating cystourethrography (MCU) did not reveal vesicoureteric reflux was substantially greater than in those who indirect isotope voiding study (IVS) did not show reflux. The risk of deterioration for those in whom reflux was demonstrated was similar for both techniques. This discrepancy indicates an appreciably higher false negative rate for the MCU than the IVS. Dilatation of the renal pelvis detected by ultrasound was associated with a significantly increased risk of progressive damage only when associated with reflux, but most children with progressive damage did not have a dilated collecting system at presentation.  相似文献   
58.
Measurements of oxygen consumption (VO2) were made during sleep in 10 patients with atopic dermatitis. Two groups of healthy children acted as controls. All subjects were studied in bed in an environmental temperature of 24-26 degrees C, and sleep was confirmed during continuous electroencephalographic monitoring. Mean (SD) values of VO2 in sleeping patients who were not scratching ranged from 4.0 (0.4) to 7.4 (0.7), which was not statistically significantly different from control values which ranged from 3.24 (0.3) to 5.56 (0.4). During scratching (while asleep), which occurred in nine out of 10 patients with atopic dermatitis, the mean values of VO2 ranged from 4.5 (0.04) to 10.4 (2.7), and this was significantly higher than the non-scratching patients and the control values. Scratching during sleep in children with atopic dermatitis is associated with increased VO2.  相似文献   
59.
60.
Organization, expression and polymorphism of the human persyn gene   总被引:13,自引:0,他引:13  
Persyn is a recently identified member of the synuclein family with a distinct pattern of expression during pre- and postnatal development of the mouse peripheral and central nervous systems. As with other synucleins, persyn is believed to be involved in the pathogenesis of human neurodegenerative diseases. However, in contrast to other synucleins, high levels of persyn mRNA expression were also found in advanced breast carcinomas, suggesting an involvement of the encoded protein in breast tumour progression. Here we have used an antibody specific to human persyn to demonstrate that the level of this protein is increased in ageing cerebral cortex and in breast tumours. We cloned, characterized and sequenced the human persyn genomic locus and localized it to the long arm of chromosome 10 in the q23.2-q23.3 region. Sequence information was used to search for specific mutations in the protein coding regions of persyn mRNA and the persyn gene in breast tumours and tumour cell lines. No tumour-specific mutations were found, but two linked polymorphisms in the coding region were detected, both in mRNA and exons III and IV of the gene. These results suggest that development of breast tumours correlates with overexpression of the wild-type persyn protein. Detailed characterization of the human persyn locus is important for further studies of the involvement of persyn in neurodegeneration and malignancy.   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