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   420篇
  免费   24篇
  国内免费   19篇
儿科学   33篇
妇产科学   11篇
基础医学   47篇
口腔科学   8篇
临床医学   50篇
内科学   71篇
皮肤病学   13篇
神经病学   11篇
特种医学   111篇
外科学   35篇
综合类   10篇
预防医学   18篇
眼科学   9篇
药学   14篇
中国医学   2篇
肿瘤学   20篇
  2024年   1篇
  2021年   1篇
  2020年   5篇
  2019年   4篇
  2018年   10篇
  2017年   4篇
  2016年   6篇
  2015年   8篇
  2014年   10篇
  2013年   12篇
  2012年   6篇
  2011年   11篇
  2010年   15篇
  2009年   21篇
  2008年   11篇
  2007年   18篇
  2006年   6篇
  2005年   6篇
  2004年   3篇
  2003年   3篇
  2002年   4篇
  2001年   7篇
  2000年   2篇
  1999年   10篇
  1998年   31篇
  1997年   38篇
  1996年   28篇
  1995年   18篇
  1994年   17篇
  1993年   17篇
  1992年   1篇
  1991年   6篇
  1990年   11篇
  1989年   20篇
  1988年   12篇
  1987年   9篇
  1986年   8篇
  1985年   10篇
  1984年   4篇
  1983年   8篇
  1982年   6篇
  1981年   2篇
  1980年   11篇
  1979年   1篇
  1978年   1篇
  1977年   6篇
  1976年   7篇
  1975年   5篇
  1970年   1篇
  1968年   1篇
排序方式: 共有463条查询结果,搜索用时 15 毫秒
131.
The pattern of cancer in white and Asian (Indian, Pakistani, and Bangladeshi) children living in the West Midlands Health Authority Region was investigated using age standardised incidence rates. Two sets of rates were calculated, a 10 year rate (1982-91) using survey based estimates of the ethnic population and a four year rate (1989-92) using the ethnic population counts from the 1991 census. The 10 year rates showed a significantly higher annual incidence of cancer in Asian (159.1/million/year) than in white (130.8) children. The pattern of cancers in Asian children was different, with an excess of lymphomas and germ cell tumours, and a deficit of rhabdomyosarcomas. These findings were confirmed by the four year rates. Although underestimation of the Asian population probably contributes to the apparent excess, there remains cause for concern that UK Asian children may be at higher risk of cancer. Accurate ethnic population figures and confirmatory studies are urgently required.  相似文献   
132.
133.
A 12 year old boy suffering from p67-phox deficient chronic granulomatous disease presented with a bullous skin disease and a lung infection with paecilomyces species. The histopathology of a bullous lesion showed subepidermal blister formation and microabcesses containing eosinophils in the dermal papillae. By direct immunofluorescence, linear staining of IgA at the dermal-epidermal junction was detected which confirmed the clinical diagnosis of chronic bullous disease of childhood (linear IgA dermatosis).  相似文献   
134.
Prior epidemiological evidence suggests that genes controlling the metabolism of carcinogens and antioxidant/nutritional status are associated with lung cancer risk, possibly through their ability to modulate DNA damage by carcinogens. We performed a cross-sectional analysis of 159 heavy smokers from a cohort of subjects enrolled in a smoking cessation program. A total of 159 blood samples were analyzed to determine the relative contributions of genetic polymorphisms [CYP1A1 MspI and exon 7 and glutathione S-transferase M1 (GSTM1)] and plasma micronutrients to polycyclic aromatic hydrocarbon-DNA (PAH-DNA) adduct levels. DNA damage in smokers was affected by genetic polymorphisms and nutritional status. Smokers with the CYP1A1 exon 7 valine polymorphism had significantly higher (2-fold, P < or = 0.03) levels of DNA damage than those without. In parallel models, PAH-DNA adducts were inversely associated with plasma levels of retinol (beta = -0.93, P = 0.01), beta-carotene (beta = -0.18, P = 0.09), and alpha- tocopherol (beta = -0.28, P = 0.21) in 159 subjects. The association between smoking-adjusted plasma beta-carotene levels and DNA damage was only significant in those subjects lacking the GSTM1 detoxification gene (beta = -0.30, P = 0.05, n = 75). There was a statistical interaction between beta-carotene and alpha-tocopherol; when beta- carotene was low, alpha-tocopherol had a significant protective effect (beta = -0.78, P = 0.04) on adducts, but not when beta-carotene was high (beta = -0.16, P = 0.57). Plasma alpha-tocopherol was significantly correlated with beta-carotene (r = 0.36, P = 0.0005) and less strongly with retinol (r = 0.20, P = 0.0005). These results suggest that several micronutrients may act in concert to protect against DNA damage and highlight the importance of assessing overall antioxidant status. In conclusion, a subset of smokers may be at increased risk of DNA damage and possibly lung cancer due to the combined effect of low plasma micronutrients and genetic susceptibility factors. The use of biological markers to assess efficacy of interventions and to study mechanisms of micronutrients is timely given the current debate regarding the use of chemopreventive agents in high risk populations.   相似文献   
135.
Basal cell carcinoma (BCC) is the commonest cancer in Caucasians. Its incidence is rising and many patients develop multiple primary tumours at separate sites. Factors determining time between first primary tumour presentation and the next new primary lesion are unclear. We used Cox's proportional hazards model to study, in 856 Caucasians, the influence of tumour site, individual characteristics and polymorphism in glutathione S-transferase (GSTM1, GSTT1) and cytochrome P450 (CYP2D6, CYP1A1) loci on time to next primary tumour presentation. More than one tumour at first presentation (P <0.0001, hazard ratio 2.72) and GSTT1 null (P = 0.028, hazard ratio 1.74) were associated with decreased time to next primary tumour presentation. Significant two- factor interactions, corrected for number of tumours at presentation, were identified between a truncal tumour at first presentation and each of male gender, GSTM1 null and CYP2D6 EM (P <0.003, hazard ratios 3.09- 3.82). In each of these cases, all patients with the risk combination demonstrated further separate tumours within 5 years of first presentation. Thus, patients with a truncal tumour at first presentation, especially males and those presenting with more than one lesion have a significantly decreased time to presentation of further tumours and should receive more meticulous follow-up. Polymorphism in GSTM1 and CYP2D6 also influences the rate of new primary tumour accrual giving insights into the link between ultraviolet exposure and multiple tumour development.   相似文献   
136.
To evaluate if an energy-dense porridge liquefied by amylase-rich flour (ARF) from germinated wheat increased the calorie intake in children with acute shigellosis, we studied 66 children, aged 6-35 months, in a randomized, controlled clinical trial. Children were randomized to receive either an energy-dense porridge liquefied with ARF (group 1), a thick unaltered porridge (group 2) or a porridge diluted with water (group 3) to a similar viscosity as that in group 1. MeanSD calorie intakes (kJ/kg/ day) from the porridges were 280 113, 167100 and 15180 in groups 1, 2 and 3, respectively (p = 0.006, ANOVA). Total energy intakes (meanSD) from the study diet and other food sources were 469151, 377121 and 351look J/kg/day, respectively (p = 0.006, ANOVA). Intake of breast milk was similar in all groups. Using multiple regression analysis the effect of ARF-treated energy-dense porridge in increasing the calorie intake persisted after adjusting for a number of confounders, such as age of the child, isolation of Shigella dysenteriae type 1 and fever. The results of this study suggest that ARF-treated porridge increases energy intake in infants and young children during acute shigellosis. This feeding approach may be useful in preventing malnutrition following dysentery due to shigellosis. Amylase, energy-dense, energy intake, liquefied, shigellosis
D Mahalanabis, Clinical Sciences Division, International Centre for Diarrhoeal Disease Research, GPO Box 128, Dhaka 1000, Bangladesh  相似文献   
137.
138.
The survival motor neuron protein in spinal muscular atrophy   总被引:19,自引:1,他引:19  
The 38 kDa survival motor neuron (SMN) protein is encoded by two ubiquitously expressed genes: telomeric SMN (SMN(T)) and centromeric SMN (SMN(C)). Mutations in SMN(T), but not SMN(C), cause proximal spinal muscular atrophy (SMA), an autosomal recessive disorder that results in loss of motor neurons. SMN is found in the cytoplasm and nucleus. The nuclear form is located in structures termed gems. Using a panel of anti-SMN antibodies, we demonstrate that the SMN protein is expressed from both the SMN(T) and SMN(C) genes. Western blot analysis of fibroblasts from SMA patients with various clinical severities of SMA showed a moderate reduction in the amount of SMN protein, particularly in type I (most severe) patients. Immunocytochemical analysis of SMA patient fibroblasts indicates a significant reduction in the number of gems in type I SMA patients and a correlation of the number of gems with clinical severity. This correlation to phenotype using primary fibroblasts may serve as a useful diagnostic tool in an easily accessible tissue. SMN is expressed at high levels in brain, kidney and liver, moderate levels in skeletal and cardiac muscle, and low levels in fibroblasts and lymphocytes. In SMA patients, the SMN level was moderately reduced in muscle and lymphoblasts. In contrast, SMN was expressed at high levels in spinal cord from normals and non- SMA disease controls, but was reduced 100-fold in spinal cord from type I patients. The marked reduction of SMN in type I SMA spinal cords is consistent with the features of this motor neuron disease. We suggest that disruption of SMN(T) in type I patients results in loss of SMN from motor neurons, resulting in the degeneration of these neurons.   相似文献   
139.
140.
The incidence and prevalence of end-stage renal disease (ESRD) continues to increase, especially in the elderly population. The role of renovascular disease in contributing to ESRD is still not well defined. The objective of this study was to determine the utility of gadolinium (Gd)-enhanced magnetic resonance angiography (MRA) in evaluating elderly patients with renal insufficiency for renal artery stenosis (RAS). A 7-month prospective study conducted in a tertiary referral center evaluated 40 consecutive patients with progressive renal insufficiency (18 men and 22 women; mean age, 70 +/- 5.6 [standard deviation] years) and high clinical suspicion for renovascular disease with Gd-enhanced MRA. Digital subtraction angiography (DSA) was obtained in only those patients with significant RAS detected by MRA. Twelve patients had significant RAS. Six of these patients had percutaneous transluminal renal angioplasty (PTRA), five patients had renal artery bypass surgery, and one patient had a stent placed after PTRA. Seventy-eight renal arteries were satisfactorily evaluated by MRA. Twenty-two renal arteries were evaluated by both MRA and DSA. Of the 12 significant stenoses detected by the MRA, 11 were confirmed by DSA and 1 was confirmed at the time of surgical revascularization. It is concluded that Gd-enhanced MRA is a useful test for the evaluation of RAS in patients with compromised renal function.  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