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   334篇
  免费   36篇
儿科学   2篇
妇产科学   1篇
基础医学   25篇
口腔科学   2篇
临床医学   46篇
内科学   86篇
皮肤病学   18篇
神经病学   15篇
特种医学   6篇
外科学   78篇
综合类   20篇
预防医学   49篇
药学   18篇
肿瘤学   4篇
  2022年   6篇
  2021年   9篇
  2020年   7篇
  2019年   6篇
  2018年   10篇
  2017年   7篇
  2016年   4篇
  2015年   14篇
  2014年   7篇
  2013年   16篇
  2012年   23篇
  2011年   22篇
  2010年   10篇
  2009年   20篇
  2008年   20篇
  2007年   20篇
  2006年   15篇
  2005年   10篇
  2004年   10篇
  2003年   14篇
  2002年   14篇
  2001年   8篇
  2000年   8篇
  1999年   4篇
  1998年   2篇
  1997年   2篇
  1996年   4篇
  1995年   1篇
  1994年   1篇
  1992年   4篇
  1991年   6篇
  1990年   3篇
  1989年   9篇
  1988年   6篇
  1987年   8篇
  1986年   7篇
  1985年   3篇
  1984年   7篇
  1983年   8篇
  1982年   2篇
  1981年   5篇
  1978年   2篇
  1977年   1篇
  1975年   1篇
  1974年   1篇
  1973年   1篇
  1964年   1篇
  1959年   1篇
排序方式: 共有370条查询结果,搜索用时 326 毫秒
101.
102.
An increased intake of soluble fiber and soy protein may improve the blood lipid profile. To assess any additional benefit on serum lipids of providing soy protein and soluble-fiber foods to hyperlipidemic subjects already consuming low-fat, low-cholesterol therapeutic diets, 20 hyperlipidemic men and postmenopausal women completed 8-week test and control dietary treatments in a randomized crossover design as part of an ad libitum National Cholesterol Education Program (NCEP) step 2 therapeutic diet (<7% saturated fat and <200 mg/d cholesterol). During the test phase, foods high in soy, other vegetable proteins, and soluble fiber were provided. During the control phase, low-fat dairy and low-soluble-fiber foods were provided. Fasting blood lipid and apolipoprotein levels were measured at 4 and 8 weeks of each phase. On the test diet, 12 +/- 2 g/d soy protein was selected from the foods chosen. Direct comparison of test and control treatments indicated an elevated high-density lipoprotein (HDL) cholesterol concentration on the test diet (6.4% +/- 2.4%, P = .013) and a significantly reduced total to HDL cholesterol ratio (-5.9% +/- 2.3%, P = .020). The proportion of conjugated dienes in the low-density lipoprotein (LDL) cholesterol fraction was significantly reduced (8.5% +/- 3.3%, P = .020) as a marker of oxidized LDL. A combination of acceptable amounts of soy, vegetable protein, and soluble-fiber foods as part of a conventional low-fat, low-cholesterol therapeutic diet is effective in further reducing serum lipid risk factors for cardiovascular disease.  相似文献   
103.
Previous research on the effect of replacing sources of animal protein with plant protein on glycemic control has been inconsistent. We therefore conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to assess the effect of this replacement on glycemic control in individuals with diabetes. We searched MEDLINE, EMBASE, and Cochrane databases through 26 August 2015. We included RCTs ≥ 3-weeks comparing the effect of replacing animal with plant protein on HbA1c, fasting glucose (FG), and fasting insulin (FI). Two independent reviewers extracted relevant data, assessed study quality and risk of bias. Data were pooled by the generic inverse variance method and expressed as mean differences (MD) with 95% confidence intervals (CIs). Heterogeneity was assessed (Cochran Q-statistic) and quantified (I2-statistic). Thirteen RCTs (n = 280) met the eligibility criteria. Diets emphasizing a replacement of animal with plant protein at a median level of ~35% of total protein per day significantly lowered HbA1c (MD = −0.15%; 95%-CI: −0.26, −0.05%), FG (MD = −0.53 mmol/L; 95%-CI: −0.92, −0.13 mmol/L) and FI (MD = −10.09 pmol/L; 95%-CI: −17.31, −2.86 pmol/L) compared with control arms. Overall, the results indicate that replacing sources of animal with plant protein leads to modest improvements in glycemic control in individuals with diabetes. Owing to uncertainties in our analyses there is a need for larger, longer, higher quality trials. Trial Registration: ClinicalTrials.gov registration number: NCT02037321.  相似文献   
104.
105.
Almonds, together with other nuts, reduce serum cholesterol levels and may reduce the risk of coronary heart disease. There is much current interest in the relation of coronary heart disease to postprandial events. We have therefore assessed the effects of varying amounts of almonds on the postprandial blood glucose response to a carbohydrate meal. Our aim was to assess the effect of adding almonds to a bread meal. Nine healthy volunteers (2 women, 7 men; mean age, 27.8 years; mean body mass index, 22.9 kg/m2) were randomly fed with 3 test meals and 2 white bread control meals on separate days. Subjects were fed the meals after a 10- to 12-hour overnight fast. Each meal contained 50 g of available carbohydrate from white bread eaten alone or with 30, 60, or 90 g ( approximately 1, 2, or 3 oz) of almonds. Capillary finger-prick blood samples for glucose analysis were obtained at 0, 15, 30, 45, 60, 90, and 120 minutes. Glycemic responses were assessed by calculating the incremental area under the 2-hour blood glucose curve. The addition of almonds to white bread resulted in a progressive reduction in the glycemic index of the composite meal in a dose-dependent manner for the 30-g (105.8 +/- 23.3), 60-g (63.0 +/- 9.0), and 90-g (45.2 +/- 5.8) doses of almonds (r = -0.524, n = 36, P = .001). We conclude that, in addition to lowering serum cholesterol levels, almonds may also reduce the glycemic impact of carbohydrate foods with which they are eaten.  相似文献   
106.
Tumor necrosis factor alpha (TNF-alpha) is a proinflammatory cytokine that impairs insulin action and alters lipid metabolism. We investigated the effects of genetic polymorphisms of TNF-alpha on circulating biomarkers of insulin resistance and lipid metabolism during an 8-hour metabolic profile test and a 2-hour oral glucose tolerance test in subjects with type 2 diabetes mellitus. Subjects (N = 123) recruited were type 2 diabetic men (n = 56) and women (n = 67) aged 36 to 75 years with a body mass index of at least 25 kg/m(2). Blood samples were collected to determine postprandial changes in circulating lipid levels and biomarkers of insulin resistance. Subjects were genotyped by polymerase chain reaction-restriction fragment length polymorphism for the TNF-alpha -238G>A, -308G>A, and -863C>A polymorphisms. Compared with subjects who were homozygous for the -238G allele, carriers of the -238A allele had an altered ability to suppress postprandial free fatty acids as shown by an increased net incremental area under the curve (0.26 +/- 2.44 vs -1.33 +/- 2.71 mEq h(-1) L(-1), P = .002) during the 8-hour metabolic profile test. This effect was observed in obese (1.04 +/- 2.42 vs -1.68 +/- 2.70 mEq h(-1) L(-1), P = .0004) but not in non-obese (-0.63 +/- 2.20 vs -0.95 +/- 2.71 mEq h(-1) L(-1), P = .6) individuals. Among obese subjects, carriers of the -308A allele had greater insulin resistance as estimated by the homeostasis model assessment of insulin resistance index (4.36 +/- 2.83 vs 2.85 +/- 1.75, P = .01), but no differences were observed among non-obese subjects (2.19 +/- 1.24 vs 1.97 +/- 0.90, P = .6). Our findings suggest that the -238G>A and -308G>A polymorphisms of TNF-alpha alter circulating free fatty acids and insulin resistance in obese subjects with type 2 diabetes mellitus.  相似文献   
107.
Summary  Nitrates may have beneficial effects on bone. To determine if nitrates were associated with increased bone mineral density (BMD), we conducted a secondary analysis using data from subjects in a prospective study. Subjects reporting nitrate use had increased BMD compared with non-users, confirming that nitrates have positive BMD effects in women and men. Introduction  Prior studies suggest positive associations between nitrates and bone. Methods  We used linear regression models, stratified by gender and adjusted for age, weight, and baseline differences, to determine the association between daily nitrate use and BMD among subjects participating in the Canadian Multicentre Osteoporosis Study. All results are reported as annualised percent change in BMD at the hip and spine among nitrate users compared to non-users. Results  We included 1,419 men (71 reported daily nitrate use) and 2,587 women (97 reported daily nitrate use). Male non-users had decreased hip BMD (−1.3%; 95% confidence interval [95%CI] = −1.6 to −1.1) and increased spine BMD (2.8%; 95%CI = 2.5 to 3.1). Male nitrate users had increased hip BMD (1.4%; 95%CI = 0.1 to 2.8) and spine BMD (4.5%; 95%CI = 3.2 to 5.7). Among women, non-users had decreased hip BMD (−1.9; 95%CI = −2.1 to −1.7) and increased spine BMD (2.1%; 95%CI = 1.9 to 2.4) whilst users had an increase in hip BMD (2.0%; 95%CI = 1.2 to 2.8) and spine BMD (4.1%; 95%CI = 3.4 to 4.9). Conclusion  Nitrate use is associated with increased BMD at the hip and spine in men and women.  相似文献   
108.
BACKGROUND:  Injuries are the leading cause of death among Canadian children and are responsible for a substantial proportion of hospitalizations and emergency department visits. This investigation sought to identify the factors associated with the likelihood of sustaining an injury at school among Ottawa-area children.
METHODS:  Children presenting to Ottawa-area hospitals and urgent care clinics from January to December 2002 (n = 24,074) were included for analysis. The frequency of school injuries by sex, age group, type of injury, and hospitalization was analyzed. Multivariate logistic regression was used to assess the factors associated with sustaining an injury at school. The school activities most associated with injury and the most frequent types of school injuries were assessed.
RESULTS:  A total of 4287 Ottawa-area children were injured at school in 2002, representing 18% of all injuries. Children aged 5-9 years and 10-14 years were more likely to have school injuries than older children (aged 15-19 years) (OR = 3.07, 95% CI = 2.77-3.40 and OR = 3.10, 95% CI = 2.83-3.37, respectively). The most frequently encountered school injuries were fractures (n = 1132) and musculoskeletal injury (n = 907). The most frequent mechanisms of school injuries were "playing" (n = 1004) and "informal sports" (n = 1503).
CONCLUSIONS:  Many children get hurt at school, particularly during informal recreation activities. Environmental modification and increased supervision are strategies that may reduce school injuries.  相似文献   
109.
Increasing brain volume may impose constraints, through longer information transfer delays, on the distributed networks supporting language. Here, we assessed the relative effects of brain volume and other putative predictors of the functional variability of perisylvian language areas, as probed with PET, during both a language comprehension and a language production task. In the case of language comprehension (story listening), a linear combination of planum temporale surface, brain volume and handedness could explain almost 60% of the functional asymmetry observed in the perisylvian area. Without brain volume, the goodness of fit was significantly decreased (39%, P < 0.05), and furthermore, the effect of handedness was not detected anymore. This was due to the fact that in our sample, left-handers (n = 12) had a significantly larger brain volume as compared to right-handers (n = 8, P = 0.03). As for language production (verb generation), brain volume and the planum temporale also played a role. However, in this case, the main predictor of functional variability was handedness, where a greater degree of right-handedness was associated with larger activation of left inferior frontal regions. Depending on the language component of interest, these results support different (yet compatible) theories on hemispheric specialization. Left specialization for comprehension could be attributed to the constraints of processing speech stimuli, while a gestural origin of language is mostly supported by the relation we observed between left specialization for production and right-handedness.  相似文献   
110.
Our objective was to estimate the relationship between longitudinal change in BMD and fragility fractures. We studied 3635 women and 1417 men 50–85 yr of age in the Canadian Multicentre Osteoporosis Study who had at least two BMD measurements (lumbar spine, femoral neck, total hip, and trochanter) within the first 5 yr of the study and fragility fractures (any, main, forearm/wrist, ribs, hip) within the first 7 yr. Multiple logistic regression was used to model the relationship between baseline BMD, BMD change, and fragility fractures. We found that, among nonusers of antiresorptives, independent of baseline BMD, a decrease of 0.01 g/cm2/yr in total hip BMD was associated with an increased risk of fragility fracture with ORs of 1.15 (95% CI: 1.01; 1.32) in women and 1.34 (95% CI: 1.02; 1.78) in men. The risk of fragility fractures in subgroups such as fast losers and those with osteopenia was better estimated by models that included BMD change than by models that included baseline BMD but excluded BMD change. Although the association between baseline BMD and fragility fractures was similar in users and nonusers of antiresorptives, the association was stronger in nonusers compared with users. These results show that BMD change in both men and women is an independent risk factor for fragility fractures and also predicts fracture risk in those with osteopenia. The results suggest that BMD change should be included with other variables in a comprehensive fracture prediction model to capture its contribution to osteoporotic fracture risk.  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