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   283篇
  免费   20篇
  2023年   2篇
  2022年   2篇
  2021年   17篇
  2020年   11篇
  2019年   5篇
  2018年   11篇
  2017年   9篇
  2016年   8篇
  2015年   13篇
  2014年   11篇
  2013年   15篇
  2012年   32篇
  2011年   18篇
  2010年   12篇
  2009年   8篇
  2008年   15篇
  2007年   18篇
  2006年   11篇
  2005年   11篇
  2004年   12篇
  2003年   3篇
  2002年   5篇
  2001年   4篇
  2000年   3篇
  1999年   2篇
  1996年   2篇
  1995年   2篇
  1992年   2篇
  1991年   5篇
  1990年   1篇
  1989年   3篇
  1988年   5篇
  1987年   1篇
  1986年   1篇
  1985年   2篇
  1984年   1篇
  1983年   1篇
  1982年   2篇
  1981年   1篇
  1978年   1篇
  1977年   1篇
  1976年   1篇
  1975年   1篇
  1974年   1篇
  1973年   2篇
  1972年   2篇
  1971年   1篇
  1967年   1篇
  1966年   3篇
  1965年   1篇
排序方式: 共有303条查询结果,搜索用时 7 毫秒
81.
A simple mathematical model for the growth of tumour with discrete time delay in the immune system is considered. The dynamical behaviour of our system by analysing the existence and stability of our system at various equilibria is discussed elaborately. We set up an optimal control problem relative to the model so as to minimize the number of tumour cells and the chemo-immunotherapeutic drug administration. Sensitivity analysis of tumour model reveals that parameter value has a major impact on the model dynamics. We numerically illustrate how does these delay can change the stability region of the immune-control equilibrium and display the different impacts to the control of tumour. Finally, epidemiological implications of our analytical findings are addressed critically.  相似文献   
82.
Molecular and Cellular Biochemistry - Membrane lipids regulate the structure and function of G protein-coupled receptors (GPCRs). Previously we have shown that membrane cholesterol regulates the...  相似文献   
83.
84.
85.
86.
Impulsivity, i.e. irresistibility in the execution of actions, may be prominent in Parkinson''s disease (PD) patients who are treated with dopamine precursors or dopamine receptor agonists. In this study, we combine clinical investigations with computational modeling to explore whether impulsivity in PD patients on medication may arise as a result of abnormalities in risk, reward and punishment learning. In order to empirically assess learning outcomes involving risk, reward and punishment, four subject groups were examined: healthy controls, ON medication PD patients with impulse control disorder (PD-ON ICD) or without ICD (PD-ON non-ICD), and OFF medication PD patients (PD-OFF). A neural network model of the Basal Ganglia (BG) that has the capacity to predict the dysfunction of both the dopaminergic (DA) and the serotonergic (5HT) neuromodulator systems was developed and used to facilitate the interpretation of experimental results. In the model, the BG action selection dynamics were mimicked using a utility function based decision making framework, with DA controlling reward prediction and 5HT controlling punishment and risk predictions. The striatal model included three pools of Medium Spiny Neurons (MSNs), with D1 receptor (R) alone, D2R alone and co-expressing D1R-D2R. Empirical studies showed that reward optimality was increased in PD-ON ICD patients while punishment optimality was increased in PD-OFF patients. Empirical studies also revealed that PD-ON ICD subjects had lower reaction times (RT) compared to that of the PD-ON non-ICD patients. Computational modeling suggested that PD-OFF patients have higher punishment sensitivity, while healthy controls showed comparatively higher risk sensitivity. A significant decrease in sensitivity to punishment and risk was crucial for explaining behavioral changes observed in PD-ON ICD patients. Our results highlight the power of computational modelling for identifying neuronal circuitry implicated in learning, and its impairment in PD. The results presented here not only show that computational modelling can be used as a valuable tool for understanding and interpreting clinical data, but they also show that computational modeling has the potential to become an invaluable tool to predict the onset of behavioral changes during disease progression.  相似文献   
87.
Gangliosides, glycosphingolipids containing sialic acid moieties, are well known mediators of transmembrane signaling and endocytosis at the plasma membrane. However, little is known about their precise regulatory role at the cell periphery for intracellular sorting of extracellular cargo. Here we inspected published scientific literature for two types of cargoes, namely bacterial toxins and viruses, regarding their usage of gangliosides. We derived a rather simple yet surprisingly consistent framework to classify 20 viruses from 12 different families and five type AB bacterial toxins into two broad categories. We propose that gangliosides with terminally attached sialic acids classify cargo for uptake and trafficking early in the endocytic pathway while gangliosides with internally attached sialic acids associate with uptake and trafficking of cargo late in the endocytic system. Our study provides a testable hypothesis for future investigations into a wide range of trafficking events. It could be utilized as a framework for other intracellular pathogens where lipids are known to be involved in recognition and trafficking. For instance, predictions can be put forward and evaluated based on ganglioside binding patterns and intracellular trafficking routes. Finally, incorporation of our classifier into large scale systems‐biology studies could help reveal related molecular determinants in subcellular sorting .  相似文献   
88.
The present study describes the usage of dried leafy biomass of mango (Mangifera indica) containing 26.3% (w/w) cellulose, 54.4% (w/w) hemicellulose, and 16.9% (w/w) lignin, as a substrate for bioethanol production from Zymomonas mobilis and Candida shehatae. The substrate was subjected to two different pretreatment strategies, namely, wet oxidation and an organosolv process. An ethanol concentration (1.21 g/L) was obtained with Z. mobilis in a shake-flask simultaneous saccharification and fermentation (SSF) trial using 1% (w/v) wet oxidation pretreated mango leaves along with mixed enzymatic consortium of Bacillus subtilis cellulase and recombinant hemicellulase (GH43), whereas C. shehatae gave a slightly higher (8%) ethanol titer of 1.31 g/L. Employing 1% (w/v) organosolv pretreated mango leaves and using Z. mobilis and C. shehatae separately in the SSF, the ethanol titers of 1.33 g/L and 1.52 g/L, respectively, were obtained. The SSF experiments performed with 5% (w/v) organosolv-pretreated substrate along with C. shehatae as fermentative organism gave a significantly enhanced ethanol titer value of 8.11 g/L using the shake flask and 12.33 g/L at the bioreactor level. From the bioreactor, 94.4% (v/v) ethanol was recovered by rotary evaporator with 21% purification efficiency.  相似文献   
89.
Molecular and Cellular Biochemistry - Myricetin is categorized under the secondary metabolite flavonoid which includes a diverse range of consumable plant parts, and it has a potential against...  相似文献   
90.
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