常曲率黎曼空间中的可展子流形

本文就常曲率空间S^m的可展子流形M^z=∞~1S^(n-1)证得若干结果,主要是:对任一n(1〈n〈m),S^m中可展子M^z的变形依赖于决定一条曲线的m-1个单参数的任意函数。

浅谈陶瓷山水画的欣赏

在陶瓷山水画的形成过程中,国画山水对陶瓷山水画的影响深远,历史悠久。山水国画的皴法、勾线、填色、构图,都对陶瓷山水画产生了重要影响。中国山水画,经东晋顾恺之发端,历南北朝到隋唐,逐渐发展成独立的画料。隋代展子虞的“游春图”是现存最早的山水画,以勾线、填色的青绿重彩法绘制,开青绿山水之先河。

Dynamic caustics experimental study on interaction between propagating crack and deformity inclusions in primary structure

The approach combining the dynamic caustics method with high-speed photography technology is used to study the interaction between propagating cracks and three kinds of deformity inclusions（ cylinder inclusion, quadruple inclusion and triangular inclusion） under lowvelocity impact loading. By recording the caustic spots of crack tips at different moments during the crack propagation, the variation regulations of dynamic stress intensity factors（ DSIF） and crack growth velocity with respect to time are obtained. The experimental results showthat the resistance effects to crack growth are varied with different shapes of inclusions in specimens, and the quadruple inclusion＇s effect is more apparent. The distortion degree of caustic spots is affected by the shapes of inclusions as well, and the situation is more serious for cylinder and quadruple inclusions. The overall values of DSIFs of triangular inclusion specimen are greater than the others, and the crack growth velocities, characteristic sizes and DSIFs showprocesses of fluctuations because of the disturbance of reflection waves in specimens. The results provide an experimental basis for the analysis of strength and impact-resistance ability in structures with deformity inclusions.

Experimental study on dynamic fracture behavior of three-point bending beam with double deformity inclusions

The dynamic fracture behavior of the three-point bending beam with double deformity inclusions under impact loading is studied by using digital high-speed photography in combination with the transmission-type dynamic caustic method. The experimental results indicate that the fluctuation of crack propagation velocity v first increases and then decreases in the crack propagation process. During the process of crack propagating into the inclusion area, the fracture resistance effect of the circular inclusion is the most significant and the effects of triangular and square inclusions are less obvious. The stress intensity factor near the crack tip increases during the propagation process and reaches its maximum value when the crack tip is close to the inclusions. The crack tip’s dynamic stress intensity factor （ DSIF） decreases when the crack exceeds the middle area of the double inclusions. These results provide an experimental basis and scientific foundation to strengthen the evaluation and fracture analysis of the structure containing deformity inclusions.

Research Progress on Methane Emission from Cropland

Methane is an important greenhouse gas, and farmland is one of the im- portant emission sources of methane. Therefore, it＇s important to study the discharge of methane from cropland. This paper reviewed the methane emission from agricultural ecosystem, the factors controlling CH4 fluxes from soil, such as water regime, the soil characteristics, and the type and amount of applied fertilizers and so on, the management for mitigation of CH4 emission from cropland, especially from paddy field, and put forward some research suggestions on methane emission in the future. The objective of this paper is to provide reference for controlling methane emission in cropland.

妈妈!原谅他吧——王震将军与他的母亲

到过王震家的人,一定会发现他家的墙上挂着一副镜框,并且一眼就会认出镜框里那位老太太就是王震的母亲,因为王震酷似生他养他的妈妈.在镜框下方的桌子上,陈放着一只骨灰盒.这就是老太太生命的归宿.这位生育了王震将军、一辈子受尽磨难的母亲,临终没有得到她期望的安寝之地,却死于他乡,装在这只小匣子里运到了家乡.这就是她的雷震之子给她最后的报答!雷震之子王震的母亲,叫董奇谱.在家当姑娘的时候,人们叫她"谱妹子";但当束起发髻,嫁到王家来之后,

南北西东

哈尔滨举办第四届冰雪电影节本届冰雪电影艺术节从一月四日起至二月束止,为期两月,举办著名电影艺术家田华电影艺术回顾展,著名香港影人徐晓明电影作品展,日本影星栗原小卷电影展,国际友好城市斯维尔德洛夫斯克电影厂影片展,北影、长影、儿影新片展等活动。(丛苗)

An Overview on Molecular Biology of Flax(Linum usitatissimum L.) in China

The advances in molecular biology research of flax （Linum usitatissimum L.）, including DNA extraction, gene cloning and transformation, molecular markers, molecular identity, genetic diversity analysis, construction of genetic linkage map etc. were summarized in this article. Meanwhile, some problems existing in flax breeding, cultivation and germplasm classification were pointed out, including less developed molecular markers, lack of target genes and usable markers, genetic linkage map covering less genome, less research on molecular biology and so on. Five constructive suggestions were finally proposed in this article to provide reference for molecular biology research and development of Chinese flax.

2015国际橡塑展圆满闭幕 参观人数呈两位数增长

CHINAPLAS 2015国际橡塑展于2015年5月23日圆满落幕,取得极大成功。尽管受恶劣天气影响,展览期间航班及列车受到延误,但参观人数仍超过2013年广州展会的规模。倾盆大雨也丝毫无法动摇买家参观国际橡塑展的决心。亚洲最大、全球第二的塑料橡胶工业展览会CHINAPLAS 2015于2015年5月20-23日广州举行,四天的参观人数录得128264名,其中尤以次日观众人数为最多,达到49 732名。

A review of numerical modeling research on the marine oil spill

Recently, as the oceanic activities are more and more frequently carried out, marine oil spill accidents bring to enormous harm to the economy and society in China, especially in the Offshore China. Marine oil spill is one kind of serious disasters which severely damages the marine environment. Aiming at the improvement of the emergency response system and response ability for the oil spill, the relative technologies on oil spill response are developed. This paper briefly introduces the developments and achievements of the oil spill numerical models, including the oil spill spreading model, the oil spill transport model, the oil particle model as well as the oil spill weathering model, which provide the theoretic criterions for the future work on the oil spill predicting and response.

茉莉花开

去年四月的一天,老公回南方老家.亲戚送了他一株茉莉.让他带回家给我放到办公室里,待到开花时它那沁人心脾的芳香定会盈满整间屋子,令入室之人赏心悦目.工作起来精神倍增。老公兴高采烈地把它带回家.我又让母亲帮忙从家中柴草垛下精心收集了一大盆肥沃土壤,把它栽种到一个极精致的花盆中。从那天开始,我每天下班后,就又多了一项任务——照顾小茉莉。其实家里还有几株其他盆栽,

Low-frequency data analysis and expansion

The use of low-frequency seismic data improves the seismic resolution, and the imaging and inversion quality. Furthermore, low-frequency data are applied in hydrocarbon exploration; thus, we need to better use low-frequency data. In seismic wavelets, the loss of low-frequency data decreases the main lobe amplitude and increases the first side lobe amplitude and results in the periodic shocking attenuation of the secondary side lobe. The loss of low frequencies likely produces pseudo-events and the false appearance of higher resolution. We use models to examine the removal of low-frequency data in seismic data processing. The results suggest that the removal of low frequencies create distortions, especially for steep structures and thin layers. We also perform low-frequency expansion using compressed sensing and sparse constraints and develop the corresponding module. Finally, we apply the proposed method to real common image point gathers with good results.

Research Progress of Biology in Coix

Coix has a long cultivation history as a minor crop in China, but many problems including unclear origin, chaos of species, loss and inaccurate use of germplasm resources exist in its research and production due to the lack of systematic study. In recent years, the importance of Coix has been realized with the exploration of its effects in treating and preventing cancer. The systematic study of Coix has met a superb development opportunity with the rapid development of biotechnology especially the deep-sequencing technique. Therefore, this paper presented here the current status of origin and evolution, classification, cytology and molecular biology progress of Coix, analyzed the ploidy of Coix and the genetic relationships with Zea, Sorghum and so on from the point of cytology, and then based on the molecular biology, analyzed the important significance of DNA molecular marker, genetic mapping and gene library in the research on identification of genetic relationship between species and genetic breeding, which could provide useful information for further Coix research.

Development of Plant Embryology in China

The development of plant embryology in China can be roughly divided into three stages: (1) the initial stage, (2) the stage of establishing plant embryology as a branch of plant sciences, and (3) the stage when plant embryology evolves into plant reproductive biology with its vigorous development. It is in the third stage that research work in this field in China has developed rapidly and many of the significant achievements obtained are described in more details in this review. Researches of experimental embryology are not included in this paper.

Advances in Studies on Molecular Mechanism of Salt Tolerance in Dunaliella salina

Dunaliella salina is known as one of the most salt-tolerant eukaryotic or- ganisms, and the most ideal model organism for studying plant adaption to high salinity. In recent years, the study on molecular mechanism of salt tolerance in Dunaliella salina has become the focus of scholars at home and abroad with the development of molecular biological techniques. This study reviewed studies on adaption of Dunaliella salina to high salinity in aspects of osmotic adjustment, salt tolerance-related genes and proteins of Dunaliella salina and signal transduction pathway of salt stress.

Plant Developmental Biology in China: Past, Present and Future

Plant development is a process from germination of seed to vegetative growth, flower initiation and development, fertilization and finally to the next generation seed formation. A lot of achievements have been obtained in plant developmental biology in China. Since the 1990's, those young generation scientists returned to China from abroad to use molecular and genetic techniques to study morphological, physiological and biochemical process of plant development. The present paper reviews the progress in some research area of plant developmental biology in the past decades and also prospects the chance and future of plant developmental studies, due to the recent advances of plant genome sequencing and functional genomics in China under the international research background.

Calculation of Valence Subband Structures for Strained Quantum-Wells by Plane Wave Expansion Method Within 6×6 Luttinger-Kohn Model

The valence subband energies and wave functions of a tensile strained quantum well are calculated by the plane wave expansion method within the 6×6 Luttinger Kohn model.The effect of the number and period of plane waves used for expansion on the stability of energy eigenvalues is examined.For practical calculation,it should choose the period large sufficiently to ensure the envelope functions vanish at the boundary and the number of plane waves large enough to ensure the energy eigenvalues keep unchanged within a prescribed range.

Environmental damage costs from fossil electricity generation in China, 2000~2003

Electricity consumption increases rapidly with the rapid development of China. The environmental damage costs of electricity generation are very important for both policy analysis and the proper management of the environment. A method was developed in this work to estimate gross environmental damage costs according to emission inventory and environmental cost factors, and to extend the costs from provincial to national level with population density. In this paper, sulfur dioxide (SO2), nitrogen oxides (NOx), particulate matter less than 10 μm in diameter (PM10), and carbon dioxide (CO2) from fossil fired power plants over 6000 kW were selected as index pollutants to quantify the environmental costs of damages on human health and global warming. With the new developed method, environmental damage costs, caused by 3 types of fired power plants in 30 provinces and 6 economic sectors during the years 2000 to 2003, were evaluated and analyzed. It can be seen that the calculated total national environmental damage costs of electricity have rapidly increased from 94930.87×106 USD in 2000 to about 141041.39×106 USD in 2003, with an average annual growth rate of 14.11%. Environmental damage costs of SO2, NOx, PM10, and CO2 are 69475.69×106, 30079.29×106, 28931.84×106, and 12554.57×106 USD and account for 49.26%, 21.33%, 20.51%, and 8.90% of total environmental costs in fossil electricity generation, respectively. With regard to regional distribution, external costs caused by fossil electricity generation are mainly concentrated in the more populated and industrialized areas of China, i.e., the Eastern Central and Southeastern areas.

Quantum Chemical Studies on Proteins in the Reaction Center of Rhodobacter sphaeroides

The electronic structure of protein chains L and M in photosynthetic reaction center (PRC) of Rhodobacter sphaeroides (Van Niel) Imhoff, Truper et Pfennig) was studied by using the Overlapping Dimer Approximation method and the Extended Negative Factor Counter method at ab initio level. The result indicated that: (1) Amino acid residues, the molecular orbitals of which composed the main components of frontier orbitals of protein chain L (M), are located at the random coil areas of chain L (alpha helix areas of chain M). Since the random coil is flexible and more easy to change its conformation in the electron transfer process and to reduce the energy of the system, and the structure of the alpha helix is reletively stable, this difference might be one of the causes for the electron transfer in photosynthetic reaction center (PRC) only takes place along the L branch. (2) The His residues which axially coordinated to the 'special pair' P and accessory chlorophyll molecules (ABChls) are essentially important for the E-LUMO levels of P and ABChl. But, the corresponding molecular orbitals of these His residues do not appear in the composition of frontier orbitals of protein chains. It means that the interaction between pigment molecules and protein chains do not influence the contribution to the frontier orbitals of protein chains explicitly, but influences the corresponding E-LUMO levels significantly.

Advances on Internal Influence Factors of Adventitious Rooting of Forest Trees

This paper reviews the internal influence factors of adventitious root, in- ducing oxidase activity, endogenous hormones, rooting inhibiting substances, and fu- ture research ideas are also proposed.