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   69篇
  免费   3篇
  2023年   2篇
  2022年   2篇
  2021年   5篇
  2020年   1篇
  2019年   5篇
  2018年   1篇
  2017年   1篇
  2016年   2篇
  2015年   4篇
  2014年   6篇
  2013年   4篇
  2012年   6篇
  2009年   4篇
  2006年   2篇
  2005年   3篇
  2004年   2篇
  2003年   3篇
  2002年   2篇
  2001年   2篇
  2000年   1篇
  1999年   1篇
  1997年   1篇
  1994年   1篇
  1991年   3篇
  1990年   1篇
  1987年   1篇
  1986年   1篇
  1982年   1篇
  1954年   1篇
  1948年   1篇
  1940年   2篇
排序方式: 共有72条查询结果,搜索用时 31 毫秒
1.
AIM: To evaluate the bone mineral density at lumbar spine and at femoral neck in a group of young adults in whom Graves' disease developed during childhood and adolescence. PATIENTS AND METHODS: We examined 28 patients (5 male, 23 female, age 20.9 +/- 3.3 years) who were 11.8 +/- 2.9 years old at the onset of Graves' disease. They were treated either with methimazole (14 patients) or with methimazole plus l-thyroxine (14 patients). At the time of the investigation, 13 patients were considered cured following antithyroid treatment, 2 were still on antithyroid drugs, 3 were on replacement therapy with l-thyroxine because of hypothyroidism, and 10, treated either surgically or with (131)I, were on replacement therapy. The bone mineral density was measured at the lumbar spine (L2-L4) and at the femoral neck, using dual-energy X-ray absorptiometry. RESULTS: The spinal bone mineral density SD score was -0.28 +/- 1.02, the femoral neck bone mineral density SD score was 0.36 +/- 1.02, and both were not different from zero (NS). We did not find any correlation between the bone mineral density of the femoral neck and that of the lumbar spine and the clinical parameters. CONCLUSION: Graves' disease, beginning in childhood and adolescence, when appropriately treated, does not affect attainment of peak bone mass.  相似文献   
2.
Two different prime-boost immunization protocols were tested in rabbits and their immune response was evaluated and compared with the final aim of defining a vaccine strategy that might be able to protect non-human primates from infection with the pathogenic simian/human immunodeficiency virus, SHIV(89.6P). The two regimens were based on three priming immunizations with either an expression plasmid plus a fowlpox (FP) recombinant vector or with two FP recombinant vectors, each one expressing either the SIV(mac239) gag/pol or the HIV-1env(89.6P) genes. In both protocols, priming immunizations were followed by two boosts with SHIV-mimicking virus-like particles (VLP). A complete SHIV-specific response was observed in all animals. Interestingly, the DNA vaccine was three to 10 times more efficient than the FP recombinant in inducing an anti-gag humoral response. Real-time PCR confirmed the memory effect on T-cell subsets secreting interleukin-4 and interferon-gamma, as a consequence of stimulation of both arms of the immune system. Although both protocols were almost equally effective in eliciting homologous neutralizing antibodies and highlighted the efficacy of VLP administration for boosting, protocol A seemed to be more effective in promoting a balanced T-cell memory immune response and appears more promising for vaccine purposes.  相似文献   
3.
4.
The Rap family of small GTP-binding proteins is composed by four different members: Rap1A, Rap1B, Rap2A and Rap2B. In this work we report the identification and characterization of a fifth member of this family of small GTPases. This new protein is highly homologous to Rap2A and Rap2B, binds labeled GTP on nitrocellulose, and is recognized by a specific anti-Rap2 antibody, but not by an anti-Rap1 antibody. The protein has thus been named Rap2C. Binding of GTP to recombinant purified Rap2C was Mg(2+)-dependent. However, accurate comparison of the kinetics of nucleotide binding and release revealed that Rap2C bound GTP less efficiently and possessed slower rate of GDP release compared to the highly homologous Rap2B. Moreover, in the presence of Mg(2+), the relative affinity of Rap2C for GTP was only about twofold higher than that for GDP, while, under the same conditions, Rap2B was able to bind GTP with about sevenfold higher affinity than GDP. When expressed in eukaryotic cells, Rap2C localized at the plasma membrane, as dictated by the presence of a CAAX motif at the C-terminus. We found that Rap2C represented the predominant Rap2 protein expressed in circulating mononuclear leukocytes, but was not present in platelets. Importantly, Rap2C was found to be expressed in human megakaryocytes, suggesting that the protein may be down-regulated during platelets generation. This work demonstrates that Rap2C is a new member of the Rap2 subfamily of proteins, able to bind guanine nucleotides with peculiar properties, and differently expressed by various hematopoietic subsets. This new protein may therefore contribute to the still poorly clarified cellular events regulated by this subfamily of GTP-binding proteins.  相似文献   
5.
Recently, the biased β2-adrenoceptor/β-arrestin pathway was shown to play a pivotal role in crossing of the blood brain barrier by Neisseria meningitidis. We hypothesized that genetic variation in the β2-adrenoceptor gene (ADRB2) may influence susceptibility to bacterial meningitis. In a prospective genetic association study we genotyped 542 patients with CSF culture proven community acquired bacterial meningitis and 376 matched controls for 2 functional single nucleotide polymorphisms in the β2-adrenoceptor gene (ADRB2). Furthermore, we analyzed if the use of non-selective beta-blockers, which bind to the β2-adrenoceptor, influenced the risk of bacterial meningitis. We identified a functional polymorphism in ADRB2 (rs1042714) to be associated with an increased risk for bacterial meningitis (Odds ratio [OR] 1.35, 95% confidence interval [CI] 1.04-1.76; p?=?0.026). The association remained significant after correction for age and was more prominent in patients with pneumococcal meningitis (OR 1.52, 95% CI 1.12-2.07; p?=?0.007). For meningococcal meningitis the difference in genotype frequencies between patients and controls was similar to that in pneumococcal meningitis, but this was not statistically significant (OR 1.43, 95% CI 0.60-3.38; p?=?0.72). Patients with bacterial meningitis had a lower frequency of non-selective beta-blockers use compared to the age matched population (0.9% vs. 1.8%), although this did not reach statistical significance (OR 1.96 [95% CI 0.88-4.39]; p?=?0.09). In conclusion, we identified an association between a genetic variant in the β2-adrenoceptor and increased susceptibility to bacterial meningitis. The potential benefit of pharmacological treatment targeting the β2-adrenoceptor to prevent bacterial meningitis in the general population or patients with bacteraemia should be further studied in both experimental studies and observational cohorts.  相似文献   
6.
Previous studies have suggested the recovery of phosphocreatine (PCr) after exercise is at least second-order in some conditions. Possible explanations for higher-order PCr recovery kinetics include heterogeneity of oxidative capacity among skeletal muscle fibers and ATP production via glycolysis contributing to PCr resynthesis. Ten human subjects (28 +/- 3 yr; mean +/- SE) performed gated plantar flexion exercise bouts consisting of one contraction every 3 s for 90 s (low-intensity) and three contractions every 3 s for 30 s (high-intensity). In a parallel gated study, the sciatic nerve of 15 adult male Sprague-Dawley rats was electrically stimulated at 0.75 Hz for 5.7 min (low intensity) or 5 Hz for 2.1 min (high intensity) to produce isometric contractions of the posterior hindlimb muscles. [(31)P]-MRS was used to measure relative [PCr] changes, and nonnegative least-squares analysis was utilized to resolve the number and magnitude of exponential components of PCr recovery. Following low-intensity exercise, PCr recovered in a monoexponential pattern in humans, but a higher-order pattern was typically observed in rats. Following high-intensity exercise, higher-order PCr recovery kinetics were observed in both humans and rats with an initial fast component (tau < 15 s) resolved in the majority of humans (6/10) and rats (5/8). These findings suggest that heterogeneity of oxidative capacity among skeletal muscle fibers contributes to a higher-order pattern of PCr recovery in rat hindlimb muscles but not in human triceps surae muscles. In addition, the observation of a fast component following high-intensity exercise is consistent with the notion that glycolytic ATP production contributes to PCr resynthesis during the initial stage of recovery.  相似文献   
7.

Background

Representing one''s own body is often viewed as a basic form of self-awareness. However, little is known about structural representations of the body in the brain.

Methods and Findings

We developed an inter-manual version of the classical “in-between” finger gnosis task: participants judged whether the number of untouched fingers between two touched fingers was the same on both hands, or different. We thereby dissociated structural knowledge about fingers, specifying their order and relative position within a hand, from tactile sensory codes. Judgments following stimulation on homologous fingers were consistently more accurate than trials with no or partial homology. Further experiments showed that structural representations are more enduring than purely sensory codes, are used even when number of fingers is irrelevant to the task, and moreover involve an allocentric representation of finger order, independent of hand posture.

Conclusions

Our results suggest the existence of an allocentric representation of body structure at higher stages of the somatosensory processing pathway, in addition to primary sensory representation.  相似文献   
8.
Exercise increases both the consumption of oxygen and the production of reactive species in biological tissues, and this is counterbalanced by antioxidant adaptations to regular physical training. When the intensity of exercise fluctuates between mild and moderate, it improves the status of reduction–oxidation balance in the brain and induces neuroplasticity. However, intense exercise can oxidize the brain and impair neurological function. The effect of the frequency of exercise, which is an important factor in physical training, is still unknown. The effect of periodic exercise on biomarkers of oxidative stress in the hippocampus of mice was evaluated in this study. Mice were made to run on a treadmill for 8 weeks, two, three, or five times per week, and their hippocampi and quadriceps femoris muscles were then dissected. Biomarkers of oxidative damage were negatively correlated with the frequency of exercise and mitochondrial muscular activity, while the sulfhydryl contents were positively correlated with exercise frequency. A logistic analysis revealed a dose-dependent effect of exercise on these biomarkers. In summary, these results suggested that manipulating the frequency of physical exercise could induce antioxidant-related adaptations in the hippocampi of adult mice.  相似文献   
9.
10.
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