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排序方式: 共有81条查询结果,搜索用时 15 毫秒
1.
基于BP神经网络的企业未来获利能力智能综合评价   总被引:3,自引:0,他引:3  
分析了相关分析——多指标综合评价法在确定企业未来获利能力方面的优点和不足 ;并在其基础上提出了基于 BP神经网络的多指标综合评价法 ;仿真试验证明了基于 BP神经网络的多指标综合评价法的有效性  相似文献   
2.
飞机百年发展与空气动力学   总被引:3,自引:1,他引:2  
飞机的发明是人类历史的一个重大转折点,飞机改变了人类社会的面貌。它使交通运输和商业往来方式发生了革命;它使战争模式发生了根本性变化;它是促进科技进步的动力;它是人类太空飞行的起点,航空与飞机将永远都是人类历史上最伟大的成就之一,回顾了飞机百年发展的基本情况和取得的主要成就,着重指出空气动力学对于飞机发展所起到的重要作用,并对未来飞机发展进行了展望。  相似文献   
3.
We investigate the ground state properties of some superheavy nuclei, which may be synthesized in future experiments. Special emphases are placed on the alpha decay energies and half-lives. The alpha decay energies and half-lives from different theoretical models are compared and discussed comprehensively. Through these calculations and comparisons, the optimal superheavy elements to be synthesized in future experiments are proposed theoretically.  相似文献   
4.
Here, an accelerated phantom model for the late universe is explored, which is free from future singularity. It is interesting to see that this model exhibits strong curvature for all time in future, unlike models with ‘big-rip singularity’ showing high curvature near singularity time only. So, quantum gravity effects grow dominant as time increases in late universe too. More importantly, it is demonstrated that quantum corrections to FRW equations lead to non-violation of ‘cosmic energy conditions’ of general relativity, which are violated for accelerating universe without these corrections.  相似文献   
5.
1 MeaningandMethodsofStudyingofFinancialDerivativesFinancialderivativesarethosefinancialproductswhicharederivedfrombasicasserts (orunderlyinginstrucments) (e .g .stock ,bond ,currency ,interestrate,etc.)oftraditionalmarkets(e.g .stockmarket,bond’smarket,currency…  相似文献   
6.
G. R. Boroun 《中国物理C(英文版)》2021,45(6):063105-063105-10
In this article,we consider the ratio of structure functions for heavy quark pair production at low values of The importance of this ratio for charm and beauty pair production is examined according to the Hadron Electron Ring Accelerator(HERA) data.The behavior of these ratios is considered due to the hard pomeron behavior of the gluon distribution function.The results are in good agreement with the HERA data.Expanding this data to the range of new energies underscores the importance of these measurements for heavy quarks.The ratio of charm and beauty structure functions at the proposed Large Hadron electron Collider(LHeC) is considered as a function of invariant center-of-mass energy.For top pair production this ratio is extracted with known kinematics of the LHeC and Future Circular Collider electron-hadron(FCC-eh) colliders.Comparison of the results obtained for the ratio of top structure functions in LHeC and FCC-eh are proportional to the specified inelasticity y range.  相似文献   
7.
This review draws together published information on the occurrence and biogeochemical cycling of selenium, arsenic and tin in the nearshore marine environment of Australia. The selenium content of marine organisms is well documented but little information is available on the selenium content of waters and sediments. The speciation of selenium in organisms, water and sediments is unknown although it appears that selenium is associated with proteins. The occurrence and speciation of arsenic in marine organisms has been extensively studied, with arsonobetaine being isolated as the probable end-product of arsenic metabolism in marine food chains. However, organisms can produce other organoarsenic compounds, e.g. trimethylarsine oxide, which may be metabolized to toxic end-products. Little is known about the occurrence and speciation of arsenic in waters and sediments. Arsenic(V) is dominant in oxygenated waters, with appreciable quantities of arsenic(III) in some deoxygenated waters. There are few data for tin in water, sediments or organisms and no data on naturally occurring tin species. Tributyltin has been measured in water, sediment and organisms from areas affected by boating activity.  相似文献   
8.
庄乾乾  程希骏  李静 《数学杂志》2016,36(4):841-850
本文研究了期货期权和裂解价差期权的定价问题.利用Fourier变换方法,在ASub CIR模型的基础上,获得了单因素期货期权,两因素期货期权以及价差期权价格的表达式,最后用C++和MATLAB计算出期权的价格,解决了利用特征函数展开法计算期权价格时速度较慢且不稳定的问题.  相似文献   
9.
It is a continuous chase of researchers to separate chiral racemates due to their dominance in the pharmaceutical industry, agrochemicals, and food additives. There are many analytical techniques which have been used to resolve one chiral center racemates, but, little the literature report is scanty for the resolution of multiple stereogenic center racemates. Therefore, in this article the efforts were made to describe the enantiomeric resolution of multiple stereogenic center racemates by different modalities of chromatography. The various modalities discussed are high-performance liquid chromatography, capillary electrophoretic chromatography, miceller electrokinetic chromatography, supercritical fluid chromatography, nanoliquid chromatography, and gas chromatography. Besides, the attempts have also been made to discuss the future challenges and prospectives of the enantiomeric resolution of multichiral racemates.  相似文献   
10.
综述了忆阻器的发明,忆阻器是2 500年前古中国神秘主义哲学家给出的一个设想,其发明可媲美门捷列夫化学元素周期表、发现太阳系行星、发现"上帝粒子"、发现宇宙超对称、捕捉到黑能量。忆阻器被称为电路世界中的第四种基本电路元件,将对未来计算和电子工程等领域产生深远的影响。  相似文献   
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