四阶段教学法在《基础会计》教学中的应用

"四阶段教学法"在世界各国的职业教育教学实践中,历史最为悠久和使用最为广泛的实践培训教学方法,多是以"示范———模仿"为核心的教学方法,它以学生为主体,以教师为主导,教与学、讲与练相结合,听、看、做、思、练五环相扣,可较好地调动学生的学习主动性与积极性,激发了学生学习的兴趣和强烈的求知欲,提高了教学质量,是一种实用有效的教学方法。

四阶段教学法——成本构成与计算

四阶段教学法,是一种把教学过程分为四个阶段的一种教学方法,这四个阶段分别是课前准备、教师示范、学生模仿、总结与练习。这种教学方法的主体是学生,同时以教师为主导,将讲与练、教与学相结合,通过看、听、思、做、练五个环节,可较好地激发学生学习兴趣,调动学生学习积极性,是一种实用有效的教学方法。

Vegetation Evolution with Degenerating Soil Ecology Under Unequal Competition

A vegetation evolution model influenced by a degeneration of soil ecological functions was set up. Three ideal communities of a) trees, b) shrubs, and c) herbage populations were first simulated. Then numerical simulations of the evolutionary and developmental processes of a natural forest community, which is composed of over 100 species,were conducted. Results of the study showed that a) in all communities, soil degeneration not only drove some weaker species to extinction, but also a few dominant ones; b) there were different response scales with species in an ideal tree metapopulation that could persist as long as a thousand years, with shrubs in an ideal shrub metapopulation that could persevere for several hundred years, and with species in an ideal herbage metapopulation that could become extinct within 10 years; and c) each metapopulation experienced three evolutionary stages during adaptation to the environment: a) the stage of compelled adaptation or resistance, b) the adjusted stage, and c) the stabilized stage.

Vehicle kinematics modeling and design of vehicle trajectory generator system

A trajectory generator based on vehicle kinematics model was presented and an integrated navigation simulation system was designed.Considering that the tight relation between vehicle motion and topography,a new trajectory generator for vehicle was proposed for more actual simulation.Firstly,a vehicle kinematics model was built based on conversion of attitude vector in different coordinate systems.Then,the principle of common trajectory generators was analyzed.Besides,combining the vehicle kinematics model with the principle of dead reckoning,a new vehicle trajectory generator was presented,which can provide process parameters of carrier anytime and achieve simulation of typical actions of running vehicle.Moreover,IMU(inertial measurement unit) elements were simulated,including accelerometer and gyroscope.After setting up the simulation conditions,the integrated navigation simulation system was verified by final performance test.The result proves the validity and flexibility of this design.

A Batesian mimic and its model share color production mechanisms

Batesian mimics are harmless prey species that resemble dangerous ones （models）, and thus receive protection from predators. How such adaptive resemblances evolve is a classical problem in evolutionary biology. Mimicry is typically thought to be difficult to evolve, especially if the model and mimic produce the convergent phenotype through different proximate mecha- nisms. However, mimicry may evolve more readily if mimic and model share similar pathways for producing the convergent phenotype. In such cases, these pathways can be co-opted in ancestral mimic populations to produce high-fidelity mimicry with- out the need for major evolutionary innovations. Here, we show that a Batesian mimic, the scarlet kingsnake Larnpropeltis elap-soides, produces its coloration using the same physiological mechanisms as does its model, the eastern coral snake Micrurus fulvius. Therefore, precise color mimicry may have been able to evolve easily in this system. Generally, we know relatively little about the proximate mechanisms underlying mimicry .

Soil Respiration of Biologically-Crusted Soils in Response to Simulated Precipitation Pulses in the Tengger Desert, Northern China

Soil respiration(SR) is a major process of carbon loss from dryland soils, and it is closely linked to precipitation which often occurs as a discrete episodic event. However, knowledge on the dynamic patterns of SR of biologically-crusted soils in response to precipitation pulses remains limited. In this study, we investigated CO_2 emissions from a moss-crusted soil(MCS) and a cyanobacterialichen-crusted soil(CLCS) after 2, 4, 8, 16, and 32 mm precipitation during the dry season in the Tengger Desert, northern China.Results showed that 2 h after precipitation, the SR rates of both MCS and CLCS increased up to 18-fold compared with those before rewetting, and then gradually declined to background levels; the decrease was faster at lower precipitation amount and slower at higher precipitation amount. The peak and average SR rates over the first 2 h in MCS increased with increasing precipitation amount, but did not vary in CLCS. Total CO_2 emission during the experiment(72 h) ranged from 1.35 to 5.67 g C m-2 in MCS, and from 1.11 to3.19 g Cm^(-2) in CLCS. Peak and average SR rates, as well as total carbon loss, were greater in MCS than in CLCS. Soil respiration rates of both MCS and CLCS were logarithmically correlated with gravimetric soil water content. Comparisons of SR among different precipitation events, together with the analysis of long-term precipitation data, suggest that small-size precipitation events have the potential for large short-term carbon losses, and that biological soil crusts might significantly contribute to soil CO_2 emission in the water-limited desert ecosystem.

Do animal eyespots really mimic eyes？

The diversity of anti-predator adaptations in the natural world has long been an active area of research in evolutionary and behavioural biology. A common visually-obvious feature found on prey are ＇eyespots＇, being approximately circular mark- ings often with concentric rings and conspicuous colours. These are found on a range of animals, especially adult and larval Lepidoptera and fish. One of the most widespread functions of eyespots seems to be to intimidate or startle predators： delaying, preventing or halting an attack. However, while the fact that they can influence predators in this way is tmcuntroversial, the mechanism（s） behind why they are effective is debated. Traditionally, they have been assumed to work by mimicking the eyes of the predator＇s own enemies, and much research in this field is conducted under the implicit or explicit assumption that this theory is correct. However, eyespots might work simply by being highly salient stimuli that promote sensory overload, biases, or neo- phobic reactions in predators. A range of recent studies has aimed to test these alternatives. Here, we critically evaluate this work and what it tells us about the mechanisms underlying eyespot function. We conclude that although eye mimicry is plausible, there remains a lack of evidence to support it and most observations are at least equally consistent with alternative mechanisms. Finally we also discuss how the debate can be resolved