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   12篇
耳鼻咽喉   5篇
儿科学   1篇
妇产科学   8篇
基础医学   41篇
口腔科学   17篇
临床医学   44篇
内科学   110篇
皮肤病学   5篇
神经病学   50篇
特种医学   9篇
外科学   64篇
综合类   1篇
预防医学   38篇
眼科学   3篇
药学   17篇
肿瘤学   19篇
  2021年   2篇
  2020年   3篇
  2019年   2篇
  2017年   3篇
  2016年   2篇
  2015年   5篇
  2014年   4篇
  2013年   16篇
  2012年   28篇
  2011年   23篇
  2010年   16篇
  2009年   17篇
  2008年   25篇
  2007年   18篇
  2006年   13篇
  2005年   21篇
  2004年   25篇
  2003年   25篇
  2002年   22篇
  2001年   16篇
  2000年   21篇
  1999年   11篇
  1998年   7篇
  1997年   4篇
  1996年   5篇
  1995年   5篇
  1994年   2篇
  1993年   8篇
  1992年   6篇
  1991年   6篇
  1990年   9篇
  1989年   2篇
  1988年   2篇
  1987年   3篇
  1986年   6篇
  1985年   8篇
  1983年   6篇
  1982年   1篇
  1981年   1篇
  1980年   3篇
  1979年   4篇
  1978年   5篇
  1976年   4篇
  1975年   1篇
  1974年   2篇
  1973年   1篇
  1972年   3篇
  1971年   2篇
  1970年   3篇
  1967年   1篇
排序方式: 共有432条查询结果,搜索用时 15 毫秒
101.
Objective - To investigate whether depression was associated with cardiac status and socio-demographic factors in patients with coronary heart disease (CHD). Methods - The sample consisted of 144 symptomatic patients with CHD. For screening depression the Beck Depression Inventory was administered on the day before elective coronary angiography. Results - Twenty-four per cent of patients had probable depressive disorder, but none of them had been previously identified as suffering from depression, or been treated for depression. Alexithymia and dissatisfaction with life were common in depressed patients. Logistic regression analysis showed that neither the cardiac status nor sociodemographic factors were associated with depression. Conclusion - Depression is a common finding and should be looked for independently of other risk factors in patients with CHD.  相似文献   
102.
OBJECTIVE: Insulin resistance decreases blood flow and volume in fat tissue. We hypothesised that fat tissue nutritive blood flow and volume, and thereby water content, would increase during weight loss and weight maintenance in obese persons. DESIGN: Longitudinal clinical intervention with a 9-week very-low-calorie diet (VLCD) followed by one year of weight maintenance. SUBJECTS: Obese men (n=13) and women (n=14) with the metabolic syndrome. MEASUREMENTS: Water content of abdominal subcutaneous fat tissue as estimated by a sensor on the skin surface measuring the dielectric constant at 300 MHz. Anthropometric measures of fatness and fat distribution. Biochemical measures related to insulin resistance. RESULTS: Subjects lost 14.5+/-3.4% of body weight during the VLCD, and generally sustained this weight loss during weight maintenance. Insulin sensitivity as estimated by an index (qualitative insulin sensitivity check index) increased during the VLCD, and remained increased throughout weight maintenance. The dielectric constant increased from 23.3+/-2.3 to 25.0+/-2.1 (P<0.001) during the VLCD, and further to 27.8+/-1.9 (P<0.001) during weight maintenance, indicating an increase in the water content of subcutaneous fat. The increase in subcutaneous fat water content did not correlate with weight loss and other measures of adiposity during the VLCD, but there was an inverse correlation that strengthened in significance from baseline to 6, 9 and 12 mo (r=-0.32 to -0.64, P=0.079-0.002). Increases in subcutaneous fat water content also correlated with improvements in insulin sensitivity at 6, 9 and 12 months of weight maintenance (r=0.34-0.54, P=0.094-0.006). CONCLUSIONS: Water content of abdominal subcutaneous adipose tissue increases with weight loss in obese persons with the metabolic syndrome, and may reflect increased subcutaneous fat tissue nutritive blood flow. The increase in water content correlates with the increase in insulin sensitivity, suggesting that weight loss and consequent improved insulin sensitivity could mediate the increase in abdominal subcutaneous fat hydration.  相似文献   
103.
Inflammation is associated with obesity, the metabolic syndrome, and diabetes. No data are available on the effect of weight reduction on the gene expression of cytokines in immune cells in obesity and the metabolic syndrome. We assessed how long-term weight loss affects expression of cytokines in peripheral blood mononuclear cells (PBMCs) in individuals with impaired glucose metabolism and the metabolic syndrome. Data from 34 subjects randomized to either a weight reduction or a control group for a 33-week period were analyzed. The messenger RNA (mRNA) expression of interleukins (ILs) in PBMCs was measured using real-time polymerase chain reaction. Measures of insulin and glucose metabolism (intravenous and oral glucose tolerance tests), body composition, and circulating adipokines and inflammatory markers were also assessed. Weight reduction resulted in a decrease in the mRNA expression of IL-1beta (IL1B), IL-1 receptor antagonist, and tumor necrosis factor alpha (P < .001) and an increase in expression of IL-6 (IL6) and IL-8 (P < .01). The increase in IL6 expression was associated with a decrease in fasting glycemia (r = -0.53, P < .01). Interestingly, the decrease in IL1B expression was correlated with an increase in insulin sensitivity index (r = -0.68, P < .01). In general, a decrease in circulating levels of adipokines and inflammatory markers was also observed after weight loss. Weight loss altered gene expression of cytokines related to inflammation and the immune response in PBMCs. Changes in IL6 mRNA expression were associated with changes in fasting glycemia. The decrease in IL-1 receptor antagonist expression after weight loss and the strong correlation between the decrease in IL1B expression and the increase in insulin sensitivity suggest a contribution of these genes to insulin-resistant states found in obesity and the metabolic syndrome.  相似文献   
104.
E Niskanen  A Kallio  P P McCann  D G Baker 《Blood》1983,61(4):740-745
Under the influence of a selective irreversible inhibitor of ornithine decarboxylase (ODC), DL-alpha-difluoromethylornithine (DFMO), early hematopoiesis was enhanced. In the bone marrow, the absolute number of cells that give rise to spleen colonies in lethally irradiated mice (CFU-S), granulocytic colonies in diffusion chambers in mice (CFU-DG), and granulocyte-monocyte colonies in agar in vitro (CFU-C) was increased 2-4 fold. This could be abrogated by administration of putrescine, confirming the association of the stimulatory effect with polyamine biosynthesis most likely via depression of ornithine decarboxylase activity and subsequent synthesis of putrescine. Analysis of cell cycle characteristics by 3H-TdR suicide technique demonstrated that the proportion of CFU-S, CFU-DG, and CFU-C in S-phase was significantly increased. Additionally, the stimulatory effect was reflected by enhanced colony formation in diffusion chambers implanted intraperitoneally in mice receiving DFMO. This could also be eliminated by treatment of the host animal with putrescine, again suggesting that polyamine biosynthesis plays an important role at the early stages of hematopoiesis in vivo. Effect of DFMO on colony formation in vitro (CFU- C) was inhibitory and not reversible with putrescine. It could be partially eliminated by aminoguanidine, which neutralizes diamine oxidase present in fetal calf serum used in the CFU-C assay. These data suggest that the effect of DFMO in vitro was nonspecific.  相似文献   
105.
We studied in a group of elderly (mean age 77 yr) non-obese Type 2 diabetic patients (n = 9) in a randomised, placebo-controlled prospective cross-over study of 8 months duration, the effects of substituting maximal sulfonylurea medication with a single injection of human zinc insulin taken either at bedtime (BTI) or morning (MI). All patients were poorly controlled with oral antidiabetic agents. After a 2-month regimen with either BTI or MI, a glibenclamide (GL, 3.5 mg/day) was given for an additional 2 months. Both insulin regimens decreased mean diurnal blood glucose and glycosylated HbA1c values to a similar extent (2.6-2.7%; p < 0.01-0.05), but with a lower daily insulin dose with BTI (0.30 +/- 0.03 IU/kg) as compared with MI (0.39 +/- 0.05 IU/kg; p < 0.01). A further improvement in metabolic control was observed in both groups after the introduction of GL; the mean reduction in glycosylated HbA1c was 1.4% for BTI and 0.7% for MI (p < 0.01 and 0.05, respectively), In conclusion, a subgroup of poorly controlled elderly Type 2 diabetic patients showed an improvement in metabolic control after a single injection of insulin despite discontinuation of maximal doses of oral antidiabetic agents. After 2 months of insulin treatment, a further improvement was achieved by a low dose of sulfonylurea in these patients who were formerly considered unresponsive to oral antidiabetic agents.  相似文献   
106.
Associations between long-term physical activity and cortical function and brain structure are poorly known. Our aim was to assess whether brain functional and/or structural modulation associated with long-term physical activity is detectable using a discordant monozygotic male twin pair design. Nine monozygotic male twin pairs were carefully selected for an intrapair difference in their leisure-time physical activity of at least three years duration (mean age 34 ± 1 years). We registered somatosensory mismatch response (SMMR) in EEG to electrical stimulation of fingers and whole brain MR images. We obtained exercise history and measured physical fitness and body composition. Equivalent electrical dipole sources of SMMR as well as gray matter (GM) voxel counts in regions of interest indicated by source analysis were evaluated. SMMR dipolar source strengths differed between active and inactive twins within twin pairs in postcentral gyrus, medial frontal gyrus and superior temporal gyrus and in anterior cingulate (AC) GM voxel counts differed similarly. Compared to active twins, their inactive twin brothers showed greater dipole strengths in short periods of the deviant-elicited SMMR and larger AC GM voxel counts. Stronger activation in early unattended cortical processing of the deviant sensory signals in inactive co-twins may imply less effective gating of somatosensory information in inactive twins compared to their active brothers. Present findings indicate that already in 30′s long-term physical activity pattern is linked with specific brain indices, both in functional and structural domains.  相似文献   
107.
BackgroundStem cell therapy is among the novel approaches for the treatment of post-myocardial infarction cardiomyopathy. This study aims to compare the effect of stromal-derived factor 1 α (SDF1α), mesenchymal stem cells (MSCs) in combination with the lentiviral production of vascular endothelial growth factor (VEGF) on infarct area, vascularization and eventually cardiac function in a rat model of myocardial infarction (MI).MethodsThe influence of SDf1α on MSCs survival was investigated. MSCs were transduced via a lentiviral vector containing VEGF. After that, the effect of mesenchymal stem cell transfection of VEGF-A165 and SDf1α preconditioning on cardiac function and scar size was investigated in five groups of MI rat models. The MSC survival, cardiac function, scar size, angiogenesis, and lymphocyte count were assessed 72 hours and 6 weeks after cell transplantation.ResultsSDF1α decreased the lactate dehydrogenase release in MSCs significantly. Also, the number of viable cells in the SDF1α-pretreated group was meaningfully more than the control. The left ventricular systolic function significantly enhanced in groups with p240MSC, SDF1αMSC, and VEGF-A165MSC in comparison to the control group.ConclusionsThese findings suggest that SDF1α pretreatment and overexpressing VEGF in MSCs could augment the MSCs' survival in the infarcted myocardium, reduce the scar size, and improve the cardiac systolic function.  相似文献   
108.
Several studies have demonstrated age-related changes in vertebral dimensions. Vertebral size has been reported to increase among elderly adults, with periosteal apposition resulting in increased cross-sectional area (CSA) of the vertebral corpus combined with reduction in bone mineral density. These changes in CSA are observed to be sex-specific, as the pronounced increase of vertebral CSA is found only in elderly males. However, the reduction in bone mineral density in old age is apparent within both sexes. It is thus hypothesized that higher fracture risk in elderly women is a result of their incapacity to increase vertebral size and thus adapt to bone mineral reduction. In this study, our aim was to explore whether the onset of these changes could be ascribed to specific age intervals and whether the proposed differences between the sexes are as great as previously suggested. To conduct this study we utilized two large early 20th century skeletal collections known as Terry and Bass (n = 181). We also utilized data from two lumbar spine magnetic resonance imaging samples as a modern-day reference (n = 497). Age, sex and ethnicity of all individuals were known. Vertebral CSA was determined by measuring three width and length dimensions from the corpus of the fourth lumbar vertebra (L4). Our results indicate only a moderate association between age and vertebral CSA. This association was observed to be relatively similar in both sexes, and we thus conclude that there is no clear sex-specific compensatory mechanism for age-related bone loss in vertebral size.  相似文献   
109.
110.
Aims: The purpose of the present study was to examine whether the association between depression and the serum high‐density lipoprotein cholesterol (HDL‐C) is modified by symptom duration. Methods: Depressed patients (n = 88) and an age‐ and sex‐matched group of healthy general population controls (n = 88) underwent a Structured Clinical Interview for DSM‐IV (SCID), and depressed participants reported the duration of their symptoms. The serum levels of total cholesterol (TC), HDL‐C, low‐density lipoprotein cholesterol (LDL‐C), triglycerides (TG) and non‐HDL, and the ratios of LDL‐C/HDL and TC/HDL‐C were assessed. Results: Major depressive disorder (MDD) subjects with a long symptom duration (≥3 years) had lower levels of HDL‐C compared with healthy controls or MDD subjects with a symptom duration <3 years. The likelihood for long symptom duration doubled for each 0.5‐mmol/L decrease in HDL‐C levels in regression models adjusted for age, gender, marital status, overweight, symptom severity, alcohol consumption, smoking, physical exercise, medication use, and non‐HDL‐C (P < 0.05). Conclusions: These findings suggest that a low serum HDL‐C level, a risk factor for coronary heart disease, is specifically associated with long‐term depressive symptomatology.  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