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   78篇
  免费   3篇
  81篇
  2022年   1篇
  2021年   10篇
  2020年   2篇
  2018年   2篇
  2016年   2篇
  2015年   5篇
  2014年   1篇
  2013年   1篇
  2012年   3篇
  2011年   9篇
  2010年   1篇
  2009年   2篇
  2008年   3篇
  2007年   2篇
  2006年   1篇
  2005年   1篇
  2004年   4篇
  2003年   2篇
  2001年   1篇
  2000年   3篇
  1998年   1篇
  1997年   1篇
  1994年   1篇
  1993年   2篇
  1992年   1篇
  1990年   3篇
  1989年   1篇
  1986年   1篇
  1984年   1篇
  1977年   3篇
  1976年   1篇
  1975年   1篇
  1972年   1篇
  1971年   2篇
  1969年   2篇
  1968年   2篇
  1967年   1篇
排序方式: 共有81条查询结果,搜索用时 15 毫秒
21.
22.
The antiviral drug, 9-(2-phosphonylmethoxyethyl) adenine (PMEA) was linked to a synthetic and neutral polymer bearing mannosyl residues to allow its internalization by macrophages via membrane lectins. PMEA bound to the mannosylated polymer was more efficient in vitro than free PMEA in preventing lysis of human macrophages by herpes virus.  相似文献   
23.
Cognitive dysfunction affects half of MS patients. Although brain atrophy generally yields the most robust MRI correlations with cognition, significant variance in cognition between individual MS patients remains unexplained. Recently, markers of cognitive reserve such as premorbid intelligence have emerged as important predictors of neuropsychological performance in MS. In the present study, we aimed to extend the cognitive reserve construct by examining the potential contribution of occupational attainment to cognitive decline in MS patients. Brain atrophy, estimated premorbid IQ, and occupational attainment were assessed in 72 MS patients. The Minimal Assessment of Cognitive Functioning in MS was used to evaluate indices of information processing speed, memory, and executive function. Results showed that occupational attainment was a significant predictor of information processing speed, memory, and executive function in hierarchical linear regressions after accounting for brain atrophy and premorbid IQ. These data suggest that MS patients with low occupational attainment fare worse cognitively than those with high occupational attainment after controlling for brain atrophy and premorbid IQ. Occupation, like premorbid IQ, therefore may make an independent contribution to cognitive outcome in MS. Information regarding an individual''s occupation is easily acquired and may serve as a useful proxy for cognitive reserve in clinical settings.  相似文献   
24.
A valid, sensitive and rapid spectrofluorimetric method has been developed and validated for determination of both tadalafil (TAD) and vardenafil (VAR) either in their pure form, in their tablet dosage forms or spiked in human plasma. This method is based on measurement of the native fluorescence of both drugs in acetonitrile at λem 330 and 470 nm after excitation at 280 and 275 nm for tadalafil and vardenafil, respectively. Linear relationships were obtained over the concentration range 4–40 and 10–250 ng/mL with a minimum detection of 1 and 3 ng/mL for tadalafil and vardenafil, respectively. Various experimental parameters affecting the fluorescence intensity were carefully studied and optimized. The developed method was applied successfully for the determination of tadalafil and vardenafil in bulk drugs and tablet dosage forms. Moreover, the high sensitivity of the proposed method permitted their determination in spiked human plasma. The developed method was validated in terms of specificity, linearity, lower limit of quantification (LOQ), lower limit of detection (LOD), precision and accuracy. The mean recoveries of the analytes in pharmaceutical preparations were in agreement with those obtained from the comparison methods, as revealed by statistical analysis of the obtained results using Student's t‐test and the variance ratio F‐test. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
25.
Talat N  Shahid F  Perry S  Dawood G  Hussain R 《Cytokine》2011,54(2):136-143
Differential T cell trafficking through the blood compartment towards infected foci may be occurring in different stages of tuberculosis disease and infection. The aim of the present study was to identify cytokine signatures in the blood compartment in tuberculosis patients with pulmonary disease (PTB=19), recently exposed household contacts (HC=27) and nonexposed community controls (EC=37). Diluted (1:10) whole blood was cultured for 2 days and cytokine secretion was assessed using Cytometric Bead Array (Th1/Th2 kit II; BD Biosciences) which included IL-2, TNF-α, IFN-γ (Type1/T1), IL-4, IL-6 and IL-10 (Type2/T2). All T1/T2 cytokines were elevated in PTB (AUROC>0.9) while HC showed selective elevation of IL-6 (AUROC>0.7) compared to EC. Principal component analysis (PCA) extracted two groupings with Eigen values >1; IL-6 separated into the second component for PTB, HC and EC. After rotation, IFN-γ was correlated with the first component for PTB and EC and the second component for HC indicating an absence of T1/T2 dichotomy. Therefore endogenous cytokine signatures may indicate differential T cell trafficking in different stages of tuberculosis infection and disease.  相似文献   
26.
The author describes the morphology and distribution of the neurosecretory cells in the supraoesophageal ganglion of the adult female Culex pipiens molestus, using paraldehyde fuchsin and paraldehyde thionine-paraldehyde fuchsin as vital staining techniques. The brain of Culex pipiens molestus has three regions (the proto-, deuto- and tritocerebrum) in which principally two types of neurosecretory cells (A and B) can be detected. Both A (dark) and B (light) cells are to be found in the protocerebrum, where they are termed medial neurosecretory cells, as they are distributed in the pars intercerebralis and only a few occur more laterally. A small group of type A and B neurosecretory cells is to be found in the posterior part of the brain (the tritocerebrum). These cells display characteristics differences in their tinctorial affinity.  相似文献   
27.
Climate warming and low pH environment are known to negatively impact all levels of aquatic organism from cellular to organism and population levels. For ammonotelic freshwater species, any abiotic factor fluctuation will cause disturbance to the fish, specifically at the gills which act as a multifunctional organ to support all biological processes. Therefore, this study was designed to investigate the effect of temperature (28 vs. 32°C) and pH (7.0 vs. 5.0) stress on the gill plasticity of Hoven's carp after 20 days of continuous exposure. The results demonstrated that high temperature and low pH caused severe changes on the primary and secondary lamellae as well as the cells within lamellae. An increasing trend of the proportion available for gas exchange was noticed at high temperature in both pH exposures, which resulted from a reduction of the primary lamellae width with elongated and thinner secondary lamellae compared to fishes at ambient temperature. Following exposure to high temperature and acidic pH, Hoven's carp experienced gill modifications including aneurysm, oedema, hypertrophy, curling of secondary lamellae, epithelial lifting, hyperplasia and lamellae fusion. These modifications are indicators of the coping mechanism of Hoven's carp to the changing environment in order to survive.  相似文献   
28.
Brain cytokines, induced by various inflammatory challenges, have been linked to sickness behaviors, including fatigue. However, the relationship between brain cytokines and fatigue after exercise is not well understood. Delayed recovery of running performance after muscle-damaging downhill running is associated with increased brain IL-1beta concentration compared with uphill running. However, there has been no systematic evaluation of the direct effect of brain IL-1beta on running performance after exercise-induced muscle damage. This study examined the specific role of brain IL-1beta on running performance (either treadmill or wheel running) after uphill and downhill running by manipulating brain IL-1beta activity via intracerebroventricular injection of either IL-1 receptor antagonist (ra; downhill runners) or IL-1beta (uphill runners). Male C57BL/6 mice were assigned to the following groups: uphill-saline, uphill-IL-1beta, downhill-saline, or downhill-IL-1ra. Mice initially ran on a motor-driven treadmill at 22 m/min and -14% or +14% grade for 150 min. After the run, at 8 h (wheel cage) or 22 h (treadmill), uphill mice received intracerebroventricular injections of IL-1beta (900 pg in 2 microl saline) or saline (2 microl), whereas downhill runners received IL-1ra (1.8 microg in 2 microl saline) or saline (2 microl). Later (2 h), running performance was measured (wheel running activity and treadmill run to fatigue). Injection of IL-1beta significantly decreased wheel running activity in uphill runners (P<0.01), whereas IL-1ra improved wheel running in downhill runners (P<0.05). Similarly, IL-1beta decreased and Il-1ra increased run time to fatigue in the uphill and downhill runners, respectively (P<0.01). These results support the hypothesis that increased brain IL-1beta plays an important role in fatigue after muscle-damaging exercise.  相似文献   
29.
Barth syndrome is an X-linked mitochondrial disease, symptoms of which include neutropenia and cardiac myopathy. These symptoms are the most significant clinical consequences of a disease, which is increasingly recognised to have a variable presentation. Mutation in the Taz gene in Xq28 is thought to be responsible for the condition, by altering mitochondrial lipid content and mitochondrial function. Male chimeras carrying a targeted mutation of Taz on their X-chromosome were infertile. Testes from the Taz knockout chimeras were smaller than their control counterparts and this was associated with a disruption of the progression of spermatocytes through meiosis to spermiogenesis. Taz knockout ES cells also showed a defect when differentiated to germ cells in vitro. Mutant spermatocytes failed to progress past the pachytene stage of meiosis and had higher levels of DNA double strand damage and increased levels of endogenous retrotransposon activity. Altogether these data revealed a novel role for Taz in helping to maintain genome integrity in meiosis and facilitating germ cell differentiation. We have unravelled a novel function for the Taz protein, which should contribute to an understanding of how a disruption of the Taz gene results in the complex symptoms underlying Barth Syndrome.  相似文献   
30.
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