如何在教学中正确处理“思考和练习”

教学实践证明,教师要准确体会编者意图,正确处理好教材中的"思考与练习",充分发挥"导教、导学、导练"的功能,才能使教师的教与学生的学融为一体,使教师上起课来得心应手,真正实现了高效与时效的课堂。

Oscillating Flat FRW Dark Energy Dominated Cosmology from Periodic Functional Approach

I discuss the modification of Einstein＇s Theory of General Relativity based on a periodic functional approach. In this new approach, a corrected periodic gravitational coupling constant arises and plays the role of periodic damping term acting on the theory. It is found that it is achievable to have an oscillating universe dominated by dark energy and expanding aceeleratedly in time.

Electronic and Optical Properties of Rock-Salt A1N under High Pressure via First-Principles Analysis

Electronic and optical properties of rock-salt AIN under high pressure are investigated by first-principlesmethod based on the plane-wave basis set.Analysis of band structures suggests that the rock-salt AIN has an indirectgap of 4.53 eV,which is in good agreement with other results.By investigating the effects of pressure on the energygap,the different movement of conduction band at X point below and above 22.5 GPa is predicted.The opticalproperties including dielectric function,absorption,reflectivity,and refractive index are also calculated and analyzed.Itis found that the rock-salt AIN is transparent from the partially ultra-violet to the visible light area and hardly does thetransparence affected by the pressure.Furthermore,the curve of optical spectrum will shift to high energy area (blueshift) with increasing pressure.

Features of SAS Enterprise Guide for probabilistic Modeling System, Macroeconomic Analysis and Forecasting

This paper addresses to the problem of using SAS Enterprise Guide 6.1 as a means for building probabilistic models and as optimum method of modeling gross domestic product in terms of the economic crisis and social threats is proposed. Today in a complex socio-political and economic situation growing influence of external factors, presence of uncertainties and risks there exists a problem of anticipating potential threats in the humanitarian and social spheres and ways to overcome them aiming to provide food security and controllability of ecological situation. All these problems, as reported in the NATO program ＂Science for Peace and Security＂, are of high priority for the countries that need to take into account threats to security, including Ukraine. That is why in the framework of the project NUKR. SFPP G4877 ＂Modeling and Mitigation of Social Disasters Caused by Catastrophes and Terrorism＂ the problems of scientific prediction of national economy for the period to 2030 as one of the measures preventing growth of social tension in the country are disclosed.

On the Importance of the American Black Fraternity and Its Enlightenment for the Fellow Townsmen Association in Chinese Universities

This paper first analyzes the benefits offered by the American Black Fraternities to the black college students in terms of improving academic achievement, cultivating leadership abilities, and enhancing social involvement on campus. Based on the successful experience of the American Black Fraternities, this paper further explores solutions to the serious problems existing in the Fellow Townsmen Association in Chinese universities to make it the same valuable asset for the development of the members＇ personality and comprehensive quality. The Association should be leveled up to an official student society to solve many of its managerial problems, and set a group goal to direct its members to the right track of serious study and completely transform the form and the content of its activities to improve the social skills of its members.

microRNAs in a multicellular green alga Volvox carteri

microRNAs(miRNAs)have emerged as key components in the eukaryotic gene regulatory network.We and others have previously identified many miRNAs in a unicellular green alga,Chlamydomonas reinhardtii.To investigate whether miRNA-mediated gene regulation is a general mechanism in green algae and how miRNAs have been evolved in the green algal lineage,we examined small RNAs in Volvox carteri,a multicellular species in the same family with Chlamydomonas reinhardtii.We identified 174 miRNAs in Volvox,with many of them being highly enriched in gonidia or somatic cells.The targets of the miRNAs were predicted and many of them were subjected to miRNA-mediated cleavage in vivo,suggesting that miRNAs play regulatory roles in the biology of green algae.Our catalog of miRNAs and their targets provides a resource for further studies on the evolution,biological functions,and genomic properties of miRNAs in green algae.

Existence Results for a Class of Periodic Evolution Variational Inequalities

In this paper, using the Brouwer topological degree, the authors prove an existence result for finite variational inequalities. This approach is also used to obtain the existence of periodic solutions for a class of evolution variational inequalities.

Effects of QCD Vacuum and the Instanton Induced-Contributions to the Nucleon Structure Functions

The instanton induced cross section in deep inelastic kinematics is a subject which people are tendentious to investigate it. Instanton induced contributions are well defined for the nucleon structure function. The non-perturbative contribution to the quark distributions of structure function, F2（x, Q2）, is considered within an instanton model for the QCD vacuum. We find that the structure function may possess numerically large non-perterbative contributions which are related to the violation of chirality and correspond to the correction of parton distribution of the leading twist. It is shown that the instantons give a negative contribution to the structure function at the NLO approximation. A comparison between our results, considering instantaon effect, and the case when we do not take this effect is done. Taking into account the instanton size, p, via the modified running coupling constant we get to a good agreement between our results at the NLO and NNLO approximations and the available experimental data, specially at the low values of the Bjorken variable x 〈 0.1 which confirms the validity of our calculations.