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   396篇
  免费   33篇
儿科学   21篇
妇产科学   1篇
基础医学   67篇
口腔科学   10篇
临床医学   23篇
内科学   79篇
皮肤病学   7篇
神经病学   54篇
特种医学   46篇
外科学   17篇
综合类   1篇
预防医学   53篇
眼科学   4篇
药学   37篇
肿瘤学   9篇
  2023年   7篇
  2022年   19篇
  2021年   7篇
  2020年   32篇
  2019年   20篇
  2018年   14篇
  2017年   6篇
  2016年   25篇
  2015年   19篇
  2014年   18篇
  2013年   16篇
  2012年   32篇
  2011年   30篇
  2010年   11篇
  2009年   13篇
  2008年   26篇
  2007年   11篇
  2006年   26篇
  2005年   17篇
  2004年   13篇
  2003年   9篇
  2002年   5篇
  1993年   2篇
  1991年   2篇
  1990年   3篇
  1987年   1篇
  1986年   4篇
  1985年   1篇
  1984年   3篇
  1982年   1篇
  1980年   1篇
  1979年   2篇
  1978年   1篇
  1977年   2篇
  1975年   1篇
  1943年   3篇
  1942年   2篇
  1941年   3篇
  1939年   2篇
  1938年   1篇
  1936年   1篇
  1935年   1篇
  1934年   1篇
  1933年   1篇
  1931年   2篇
  1930年   1篇
  1929年   1篇
  1927年   1篇
  1918年   1篇
  1913年   1篇
排序方式: 共有429条查询结果,搜索用时 15 毫秒
31.
This study determines the prevalence of atopic dermatitis, asthma, rhinoconjunctivitis, food hypersensitivity and urticaria and the frequency of sensitization in children with and without clinical allergic disease. In an ongoing prospective non-interventional birth cohort study of 562 unselected children, 404 children were subjected to interview, clinical examination, lung function measurements and allergy testing at 6 yr of age. Sensitization measured by skin prick test (SPT) and specific immunoglobulin E (S-IgE) was determined for 24 different allergens. The 1-yr period prevalence of atopic dermatitis, asthma and rhinoconjunctivitis was 14.4%, 6.2% and 13.6%. 25.7% of the children suffered from at least one of the three diseases. The frequency of sensitization in children with no disease (controls), any allergic disease, atopic dermatitis, asthma and rhinoconjunctivitis was 17%, 45%, 47%, 56% and 55% (defined as SPT ≥3 mm and/or S-IgE ≥0.35 kU/l for at least one allergen). Symptoms were linked to sensitization for 44% in the asthma group and 42% in the rhinoconjunctivitis group, whereas sensitization could not be linked to worsening of the eczema in any cases of atopic dermatitis. Overlap between the three diseases was significantly more frequent in sensitized children than in non-sensitized (19/46 = 41% vs. 9/58 = 16%, p = 0.004). The prevalence of food hypersensitivity and urticaria was 1.2% and 5.4% respectively. In unselected 6 yr old children, approximately half of the children with atopic dermatitis, asthma or rhinoconjunctivitis are IgE-sensitized. Sensitization tends to link these diseases to each other.  相似文献   
32.
33.
34.
BACKGROUND: Studies have linked epilepsy with an increased suicide risk, but the association might be modified by psychiatric, demographic, and socioeconomic factors. METHODS: Suicide cases were identified in the Cause of Death Register in Denmark from 1981 to 1997. Up to 20 controls, matched by sex, birth year, and calendar date, were assigned to each suicide case. FINDINGS: We identified 21 169 cases of suicide and 423 128 controls. 492 (2.32%) individuals who committed suicide had epilepsy compared with 3140 (0.74%) controls, corresponding to a three times higher risk (rate ratio [RR] 3.17 [95% CI 2.88-3.50]; p<0.0001). The RR remained high after excluding those with a history of psychiatric disease and adjusting for socioeconomic factors (1.99, 1.71-2.32; p<0.0001). The highest risk of suicide was identified in patients with epilepsy and comorbid psychiatric disease, even after adjusting for socioeconomic factors (13.7, 11.8-16.0; p<0.0001). In individuals with epilepsy, the highest risk of suicide was found during the first half year after diagnosis was made (5.35, 3.43-8.33; p<0.0001), and was especially high in those with a history of comorbid psychiatric disease (29.2, 16.4-51.9; p<0.0001). INTERPRETATION: Individuals with epilepsy have a higher risk of suicide, even if coexisting psychiatric disease, demographic differences, and socioeconomic factors are taken into account. Our study identifies people with newly diagnosed epilepsy as a vulnerable group that require special attention.  相似文献   
35.
36.
We present a technique to measure the longitudinal relaxation time constant of venous blood (T1b) in vivo in a few seconds. The MRI sequence consists of a thick‐slab adiabatic inversion, followed by a series of slice‐selective excitations and single‐shot echo planar imaging readouts. The time intervals between excitations were chosen so that blood in macroscopic vessels is fully refreshed between excitations, making the blood signal follow an unperturbed inversion recovery curve. Static tissue, which experiences the inversion and all excitation pulses, quickly reaches a steady state at a low signal as a result of partial saturation. This allows blood‐filled voxels to be discriminated from those containing static tissue, and to be fitted voxel‐by‐voxel to a simple inversion recovery model. The sequence was tested on a flow phantom with the proposed method, yielding T1 values consistent to within 3% of those obtained using a conventional inversion recovery sequence with a spin‐echo readout. The method was applied to seven adult volunteers and 18 neonates. The blood T1 of the neonates (1799 ± 206 ms; range, 1393–2035 ms) was found to be more variable than that of adults (1717 ± 39 ms; range, 1662–1779 ms). A linear correlation between the inverse of T1b and the haematocrit was established in 12 neonates (R2 = 0.90). Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   
37.

Background  

It has recently been shown that overexpression of the serine protease, matriptase, in transgenic mice causes a dramatically increased frequency of carcinoma formation. Overexpression of HAI-1 and matriptase together changed the frequency of carcinoma formation to normal. This suggests that the ratio of matriptase to HAI-1 influences the malignant progression. The aim of this study has been to determine the ratio of matriptase to HAI-1 mRNA expression in affected and normal tissue from individuals with colorectal cancer adenomas and carcinomas as well as in healthy individuals, in order to determine at which stages a dysregulated ratio of matriptase/HAI-1 mRNA is present during carcinogenesis.  相似文献   
38.
Acute effects of ghrelin administration on glucose and lipid metabolism   总被引:11,自引:0,他引:11  
CONTEXT: Ghrelin infusion increases plasma glucose and nonesterified fatty acids, but it is uncertain whether this is secondary to the concomitant release of GH. OBJECTIVE: Our objective was to study direct effects of ghrelin on substrate metabolism. DESIGN: This was a randomized, single-blind, placebo-controlled two-period crossover study. SETTING: The study was performed in a university clinical research laboratory. PARTICIPANTS: Eight healthy men aged 27.2 +/- 0.9 yr with a body mass index of 23.4 +/- 0.5 kg/m(2) were included in the study. INTERVENTION: Subjects received infusion of ghrelin (5 pmol x kg(-1) x min(-1)) or placebo for 5 h together with a pancreatic clamp (somatostatin 330 microg x h(-1), insulin 0.1 mU x kg(-1) x min(-1), GH 2 ng x kg(-1) x min(-1), and glucagon 0.5 ng.kg(-1) x min(-1)). A hyperinsulinemic (0.6 mU x kg(-1) x min(-1)) euglycemic clamp was performed during the final 2 h of each infusion. RESULTS: Basal and insulin-stimulated glucose disposal decreased with ghrelin [basal: 1.9 +/- 0.1 (ghrelin) vs. 2.3 +/- 0.1 mg x kg(-1) x min(-1), P = 0.03; clamp: 3.9 +/- 0.6 (ghrelin) vs. 6.1 +/- 0.5 mg x kg(-1) x min(-1), P = 0.02], whereas endogenous glucose production was similar. Glucose infusion rate during the clamp was reduced by ghrelin [4.0 +/- 0.7 (ghrelin) vs. 6.9 +/- 0.9 mg.kg(-1) x min(-1); P = 0.007], whereas nonesterified fatty acid flux increased [131 +/- 26 (ghrelin) vs. 69 +/- 5 micromol/min; P = 0.048] in the basal period. Regional lipolysis (skeletal muscle, sc fat) increased insignificantly with ghrelin infusion. Energy expenditure during the clamp decreased after ghrelin infusion [1539 +/- 28 (ghrelin) vs. 1608 +/- 32 kcal/24 h; P = 0.048], but the respiratory quotient did not differ. Minor but significant elevations in serum levels of GH and cortisol were observed after ghrelin infusion. CONCLUSIONS: Administration of exogenous ghrelin causes insulin resistance in muscle and stimulates lipolysis; these effects are likely to be direct, although a small contribution of GH and cortisol cannot be excluded.  相似文献   
39.
The present study explored when and how emotional difficulties and poor quality of life arise in the everyday lives of socially anxious individuals. 264 freshmen-year college students completed an online survey for 11 consecutive days. Comparing individuals high (HSA) and low in social anxiety, results revealed that irrespective of daily positive emotion differentiation ability, HSAs engaged daily emotion suppression strategies, pointing to inflexible emotion regulation. Furthermore, HSAs with poor daily negative emotion differentiation used the least daily cognitive reappraisal. Finally, both expressive suppression and cognitive reappraisal showed group-specific effects on daily positive affect. Daily expressive suppression was more strongly associated with diminished daily positive affect in HSAs, and HSAs benefited less in terms of daily positive affect from daily use of cognitive reappraisal. Based on these findings, emotion differentiation ability and emotion regulation appear relevant clinical targets for individuals with social anxiety disorder.  相似文献   
40.
OBJECTIVE: Concentrations of the orexigenic peptide ghrelin is affected by a number of hormones, which also affect circulating levels of free fatty acids (FFAs). The present study was therefore designed to determine the direct effect of FFAs on circulating ghrelin. DESIGN: Eight lean, healthy men were examined for 8 h on four occasions using variable infusion rates (0, 3, 6 and 12 microl/kg per min) of intralipid to create different plasma FFA concentrations. Constant levels of insulin and GH were obtained by administration of acipimox (250 mg) and somatostatin (300 microg/h). At the end of each study day a hyperinsulinaemic-euglycaemic clamp was performed. RESULTS: Four distinct levels of FFAs were obtained at the end of the lipid infusion period (FFA(LIPID): 0.03 +/- 0.00 vs: 0.49 +/- 0.04, 0.92 +/- 0.08 and 2.09 +/- 0.38 mmol/l; ANOVA P < 0.0001) and during hyperinsulinaemia (FFA(LIPID+INSULIN): 0.02 +/- 0.00 vs: 0.34 +/- 0.03, 0.68 +/- 0.09 and 1.78 +/- 0.32 mmol/l; ANOVA P < 0.0001). Whereas, somatostatin infusion alone reduced ghrelin concentration by approximately 67%, concomitant administration of increasing amounts of intralipid reduced circulating ghrelin by a further 14, 19 and 19% respectively (change in ghrelin: 0.52 +/- 0.05 vs: 0.62 +/- 0.06, 0.72 +/- 0.09 and 0.71 +/- 0.05 microg/l; ANOVA P = 0.04). No further reduction in ghrelin concentration was observed during hyperinsulinaemia. CONCLUSION: FFA exposure between 0 and 1 mmol/l significantly suppresses ghrelin levels independent of ambient GH and insulin levels.  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