全文获取类型
收费全文 | 159篇 |
免费 | 2篇 |
出版年
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 3篇 |
2013年 | 2篇 |
2012年 | 2篇 |
2011年 | 2篇 |
2010年 | 3篇 |
2009年 | 3篇 |
2008年 | 2篇 |
2005年 | 2篇 |
2003年 | 2篇 |
2001年 | 4篇 |
2000年 | 5篇 |
1999年 | 2篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1989年 | 2篇 |
1986年 | 2篇 |
1977年 | 2篇 |
1960年 | 4篇 |
1959年 | 2篇 |
1957年 | 2篇 |
1953年 | 3篇 |
1947年 | 2篇 |
1945年 | 1篇 |
1940年 | 2篇 |
1939年 | 1篇 |
1938年 | 4篇 |
1937年 | 2篇 |
1936年 | 9篇 |
1935年 | 5篇 |
1934年 | 2篇 |
1933年 | 8篇 |
1932年 | 9篇 |
1931年 | 9篇 |
1930年 | 2篇 |
1929年 | 7篇 |
1927年 | 1篇 |
1926年 | 1篇 |
1924年 | 2篇 |
1923年 | 3篇 |
1922年 | 1篇 |
1920年 | 2篇 |
1919年 | 1篇 |
1918年 | 3篇 |
1916年 | 1篇 |
1914年 | 1篇 |
1910年 | 2篇 |
1909年 | 1篇 |
1907年 | 1篇 |
排序方式: 共有161条查询结果,搜索用时 31 毫秒
1.
Hardies SC; Martin SL; Voliva CF; Hutchison CA d; Edgell MH 《Molecular biology and evolution》1986,3(2):109-125
2.
Synchronous network excitation is believed to play an outstanding role in neuronal information processing. Due to the stochastic
nature of the contributing neurons, however, those synchronized states are difficult to detect in electrode recordings. We
present a framework and a model for the identification of such network states and of their dynamics in a specific experimental
situation. Our approach operationalizes the notion of neuronal groups forming assemblies via synchronization based on experimentally
obtained spike trains. The dynamics of such groups is reflected in the sequence of synchronized states, which we describe
as a renewal dynamics. We furthermore introduce a rate function which is dependent on the internal network phase that quantifies
the activity of neurons contributing to the observed spike train. This constitutes a hidden state model which is formally
equivalent to a hidden Markov model, and all its parameters can be accurately determined from the experimental time series
using the Baum-Welch algorithm. We apply our method to recordings from the cat visual cortex which exhibit oscillations and
synchronizations. The parameters obtained for the hidden state model uncover characteristic properties of the system including
synchronization, oscillation, switching, background activity and correlations. In applications involving multielectrode recordings,
the extracted models quantify the extent of assembly formation and can be used for a temporally precise localization of system
states underlying a specific spike train.
Received: 30 March 1993/Accepted in revised form: 16 April 1994 相似文献
3.
We present a novel framework for the analysis of time series from dynamical systems that alternate between different operating
modes. The method simultaneously segments and identifies the dynamical modes by using predictive models. In extension to previous
approaches, it allows an identification of smooth transition between successive modes. The method can be used for analysis,
diagnosis, prediction, and control. In an application to EEG and respiratory data recorded from humans during afternoon naps,
the obtained segmentations of the data agree with the sleep stage segmentation of a medical expert to a large extent. However,
in contrast to the manual segmentation, our method does not require a priori knowledge about physiology. Moreover, it has
a high temporal resolution and reveals previously unclassified details of the transitions. In particular, a parameter is found
that is potentially helpful for vigilance monitoring. We expect that the method will generally be useful for the analysis
of nonstationary dynamical systems, which are abundant in medicine, chemistry, biology and engineering.
Received: 5 May 1999 / Accepted in revised form: 28 December 1999 相似文献
4.
5.
R Moriggi Jr HS Di Mauro SC Dias JM Matos MB Urtado NF Camar?o IV Sousa Neto DC Nascimento RA Tibana CO Assump??o J Prestes CB Urtado 《Biology of sport / Institute of Sport》2015,32(4):289-294
Low intensity resistance exercise (RE) with blood flow restriction (BFR) has gained attention in the literature due to the beneficial effects on functional and morphological variables, similar to those observed during traditional RE without BFR, while the effects of BFR on post-exercise hypotension remain unclear. The aim of the present study was to compare the blood pressure (BP) response of trained normotensive individuals to RE with and without BFR. In this cross-over randomized trial, eight male subjects (23.8 ± 4 years, 74 ± 3 kg, 174 ± 4 cm) completed two exercise protocols: traditional RE (3 x 10 repetitions at 70% one-repetition maximum [1-RM]) and low intensity RE (3 x 15 repetitions at 20% 1-RM) with BFR. Blood pressure measurements were performed after 15 min of seated rest (0), immediately after and 10 min, 20 min, 30 min, 40 min, 50 min and 60 min after the experimental sessions. Similar hypotensive effects for systolic BP (SBP) were observed for both protocols (P < 0.05) after exercise, with no differences between groups (P > 0.05) and no statistically significant difference for diastolic BP (P > 0.05). These results suggest that in normotensive trained individuals, both traditional RE and RE with BFR induce hypotension for SBP, which is important to prevent cardiovascular disturbances. 相似文献
6.
JY Xiong SC Li YX Sun XS Zhang ZZ Dong P Zhong XR Sun 《Biology of sport / Institute of Sport》2015,32(4):295-300
Increasing evidence suggests that physical activity could delay or attenuate the symptoms of Alzheimer''s disease (AD). But the underlying mechanisms are still not fully understood. To investigate the effect of long-term treadmill exercise on the spatial memory of AD mice and the possible role of β-amyloid, brain-derived neurotrophic factor (BDNF) and microglia in the effect, male APPswe/PS1dE9 AD mice aged 4 months were subjected to treadmill exercise for 5 months with 6 sessions per week and gradually increased load. A Morris water maze was used to evaluate the spatial memory. Expression levels of β-amyloid, BDNF and Iba-1 (a microglia marker) in brain tissue were detected by immunohistochemistry. Sedentary AD mice and wildtype C57BL/6J mice served as controls. The results showed that 5-month treadmill exercise significantly decreased the escape latencies (P < 0.01 on the 4th day) and improved the spatial memory of the AD mice in the water maze test. Meanwhile, treadmill exercise significantly increased the number of BDNF-positive cells and decreased the ratios of activated microglia in both the cerebral cortex and the hippocampus. However, treadmill exercise did not significantly alleviate the accumulation of β-amyloid in either the cerebral cortex or the hippocampus of the AD mice (P > 0.05). The study suggested that long-term treadmill exercise could improve the spatial memory of the male APPswe/PS1dE9 AD mice. The increase in BDNF-positive cells and decrease in activated microglia might underpin the beneficial effect. 相似文献
7.
8.
9.
10.
EO Ogueji CD Nwani SC Iheanacho CE Mbah CO Okeke A Yaji 《African Journal of Aquatic Science》2018,43(3):293-303
Indiscriminate discharge of pharmaceutical waste into the aquatic ecosystem may pose serious health challenges to aquatic biota. The effect of acute exposure to ibuprofen was evaluated using changes in behaviour and haematological parameters under static bio-assay method in Clarias gariepinus. Test specimens were exposed to acute concentrations of ibuprofen (0.28, 0.33, 0.38, 0.43 and 0.48 mg l?1) for 24, 48, 72 and 96 h durations respectively. Behavioural and phenotypic changes were observed in surviving fish. There were significant (p < 0.05) concentration and duration-dependent increases in erythrocyte (RBC), haemoglobin (Hb), pack cell volume (PCV) and leukocytes (WBC) in treated fish compared to the control. Insignificant decreases (p > 0.05) in mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) were observed in treated fish compared to the control. Ibuprofen elicited dose and duration- dependent decrease in neutrophil counts with the decreases being significant (p < 0.05) in the higher doses of 0.43 and 0.48 mg l?1. Ibuprofen did not elicit any significant changes in monocytes, basophils and eosinophils. Changes observed in this study showed that ibuprofen negatively affected the health of the fish and we recommend that discharge of ibuprofen into the aquatic environment should be monitored and controlled. 相似文献