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   42篇
  免费   1篇
  43篇
  2021年   1篇
  2020年   1篇
  2015年   1篇
  2014年   6篇
  2013年   5篇
  2012年   3篇
  2011年   4篇
  2010年   2篇
  2009年   7篇
  2008年   5篇
  2007年   4篇
  2005年   1篇
  2001年   1篇
  1998年   2篇
排序方式: 共有43条查询结果,搜索用时 46 毫秒
11.
This article analyses revolutionary social change by exploring how people attempt to create a radically different future by taking action in the present, and the challenges that beset this transformation. Examining the relationship between the future, the present, and the past, the article takes the case of the spread of armed underground Maoist guerrillas in India to ask two questions: First, why does India hang on to this form of utopianism when the rest of the world appears to have abandoned it? Second, how and why does the ‘muck of the past’ influence the production of a radically different future? In answering these questions, this article suggests that for both processes of radical social change and our theories of them, we need to reinsert our analyses of politico‐economic conditions into our ideologies of social change.  相似文献   
12.
Surrogate indexes of visceral adiposity, a major risk factor for metabolic and cardiovascular disorders, are routinely used in clinical practice because objective measurements of visceral adiposity are expensive, may involve exposure to radiation, and their availability is limited. We compared several surrogate indexes of visceral adiposity with ultrasound assessment of subcutaneous and visceral adipose tissue depots in 99 young Caucasian adults, including 20 women without androgen excess, 53 women with polycystic ovary syndrome, and 26 men. Obesity was present in 7, 21, and 7 subjects, respectively. We obtained body mass index (BMI), waist circumference (WC), waist-hip ratio (WHR), model of adipose distribution (MOAD), visceral adiposity index (VAI), and ultrasound measurements of subcutaneous and visceral adipose tissue depots and hepatic steatosis. WC and BMI showed the strongest correlations with ultrasound measurements of visceral adiposity. Only WHR correlated with sex hormones. Linear stepwise regression models including VAI were only slightly stronger than models including BMI or WC in explaining the variability in the insulin sensitivity index (yet BMI and WC had higher individual standardized coefficients of regression), and these models were superior to those including WHR and MOAD. WC showed 0.94 (95% confidence interval 0.88–0.99) and BMI showed 0.91 (0.85–0.98) probability of identifying the presence of hepatic steatosis according to receiver operating characteristic curve analysis. In conclusion, WC and BMI not only the simplest to obtain, but are also the most accurate surrogate markers of visceral adiposity in young adults, and are good indicators of insulin resistance and powerful predictors of the presence of hepatic steatosis.  相似文献   
13.
Dicationic 2,6-diphenylpyrazines, aza-analogues and prodrugs were synthesized; evaluated for DNA affinity, activity against Trypanosoma brucei rhodesiense (T. b. r.) and Plasmodium falciparum (P. f.) in vitro, efficacy in T. b. r. STIB900 acute and T. b. brucei GVR35 CNS mouse models. Most diamidines gave poly(dA-dT)2 ΔTm values greater than pentamidine, IC50 values: T. b. r. (4.8–37 nM) and P. f. (10–52 nM). Most diamidines and prodrugs gave cures for STIB900 model (11, 19a and 24b 4/4 cures); 12 3/4 cures for GVR35 model. Metabolic stability half-life values for O-methylamidoxime prodrugs did not correlate with STIB900 results.  相似文献   
14.
15.
16.
Deep inspirations modulate airway caliber and airway closure and their effects are impaired in asthma. The association between asthma and obesity raises the question whether the deep inspiration (DI) effect is also impaired in the latter condition. We assessed the DI effects in obese and nonobese nonasthmatics. Thirty-six subjects (17 obese, 19 nonobese) underwent routine methacholine (Mch) challenge and 30 of them also had a modified bronchoprovocation in the absence of DIs. Lung function was monitored with spirometry and forced oscillation (FO) [resistance (R) at 5 Hz (R5), at 20 Hz (R20), R5-R20 and the integrated area of low-frequency reactance (AX)]. The response to Mch, assessed with area under the dose-response curves (AUC), was consistently greater in the routine challenge in the obese (mean ± SE, obese vs. nonobese AUC: R5: 15.7 ± 2.3 vs. 2.4 ± 2.0, P < 0.0005; R20: 5.6 ± 1.4 vs. 1.4 ± 1.2, P = 0.027; R5-R20: 10.2 ± 1.6 vs. 0.9 ± 0.1.4, P < 0.0005; AX: 115.6 ± 22.0 vs. 1.5 ± 18.9, P < 0.0005), but differences between groups in the modified challenge were smaller, indicating reduced DI effects in obesity. Given that DI has bronchodilatory and bronchoprotective effects, we further assessed these components separately. In the obese subjects, DI prior to Mch enhanced Mch-induced bronchoconstriction, but DI after Mch resulted in bronchodilation that was of similar magnitude as in the nonobese. We conclude that obesity is characterized by increased Mch responsiveness, predominantly of the small airways, due to a DI effect that renders the airways more sensitive to the stimulus.  相似文献   
17.
Climate change and invasive species can both have negative impacts on native species diversity. Additionally, climate change has the potential to favor invasive species over natives, dealing a double blow to native biodiversity. It is, therefore, vital to determine how changing climate conditions are directly linked to demographic rates and population growth of non-native species so we can quantitatively evaluate how invasive populations may be affected by changing conditions and, in turn, impact native species. Cordylophora caspia, a hydrozoan from the Ponto-Caspian region, has become established in the brackish water habitats of the San Francisco Estuary (SFE). We conducted laboratory experiments to study how temperature and salinity affect C. caspia population growth rates, in order to predict possible responses to climate change. C. Caspia population growth increased nonlinearly with temperature and leveled off at a maximum growth rate near the annual maximum temperature predicted under a conservative climate change scenario. Increasing salinity, however, did not influence growth rates. Our results indicate that C. caspia populations in the SFE will benefit from predicted regional warming trends and be little affected by changes in salinity. The population of C. caspia in the SFE has the potential to thrive under future climate conditions and may subsequently increase its negative impact on the food web.  相似文献   
18.
Loss of dopamine (DA) homeostasis may be a contributing factor to cell damage in Parkinson's disease (PD). Past studies showing deleterious effects of DA on mitochondrial function, however, have been inconsistent raising questions about mitochondria as a downstream target for DA. Issues such as the dopamine species i.e., reduced or oxidized, time of exposure and the effect of major metabolites such as 3,4-dihydrophenylacetic acid (DOPAC) may contribute to the disparate findings. The present study used isolated, lysed rat brain mitochondria to characterize the effects of oxidized or reduced DA and DOPAC on complex activities of the electron transport chain (ETC). Time of exposure and quantitation of reduced or oxidized catachols for DA and DOPAC were monitored for all experiments. Reduced DA and DOPAC with or without a 30min preincubation had no affect on NADH oxidase activity which monitors the activities of complexes I, III and IV. Complex II activity was inhibited by reduced DA (≥500μM), but not by reduced DOPAC and was significantly attenuated by SOD suggesting reactive oxygen species involvement. In contrast, fully oxidized DA and DOPAC dose dependently inhibited NADH oxidase, complex I and complex III activities with IC(50s) in the 50-200μM range. No preincubation was required for inhibition with the catechols when they were fully oxidized. Oxidized DA inhibited complex I only when exposure occurred during stimulated electron flow, suggesting covalent binding of quinones to proteins within active sites of the complex. In intact, well coupled mitochondria, extramitochondrial DA was shown to access the mitochondrial matrix in a dose, time and energy-dependent fashion. The findings suggest that many of the reported inconsistencies with regards to the effects of DA and DOPAC on ETC function can be attributed to the oxidized state of the catechol at the time of exposure. In addition, the findings provide possible downstream targets for DA that could contribute to the vulnerability of dopaminergic neurons in PD.  相似文献   
19.
20.
Pooled analyses among whites and East Asians have demonstrated positive associations between all-cause mortality and body mass index (BMI), but studies of African Americans have yielded less consistent results. We examined the association between BMI and all-cause mortality in a sample of African Americans pooled from seven prospective cohort studies: NIH-AARP, 1995–2009; Adventist Health Study 2, 2002–2008; Black Women''s Health Study, 1995–2009; Cancer Prevention Study II, 1982–2008; Multiethnic Cohort Study, 1993–2007; Prostate, Lung, Colorectal and Ovarian Screening Trial, 1993–2009; Southern Community Cohort Study, 2002–2009. 239,526 African Americans (including 100,175 never smokers without baseline heart disease, stroke, or cancer), age 30–104 (mean 52) and 71% female, were followed up to 26.5 years (mean 11.7). Hazard ratios (HR) and 95% confidence intervals (CI) for mortality were derived from multivariate Cox proportional hazards models. Among healthy, never smokers (11,386 deaths), HRs (CI) for BMI 25–27.4, 27.5–29.9, 30–34.9, 35–39.9, 40–49.9, and 50–60 kg/m2 were 1.02 (0.92–1.12), 1.06 (0.95–1.18), 1.32 (1.18–1.47), 1.54 (1.29–1.83), 1.93 (1.46–2.56), and 1.93 (0.80–4.69), respectively among men and 1.06 (0.99–1.15), 1.15 (1.06–1.25), 1.24 (1.15–1.34), 1.58 (1.43–1.74), 1.80 (1.60–2.02), and 2.31 (1.74–3.07) respectively among women (reference category 22.5–24.9). HRs were highest among those with the highest educational attainment, longest follow-up, and for cardiovascular disease mortality. Obesity was associated with a higher risk of mortality in African Americans, similar to that observed in pooled analyses of whites and East Asians. This study provides compelling evidence to support public health efforts to prevent excess weight gain and obesity in African Americans.  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