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1.
首先简单介绍了对于有理数域上光滑射影曲线的Beilinson猜想,然后应用椭圆簇的知识指出了存在于费玛曲线K2群中的一个元素,最后在费玛曲线X3这个特殊情形下,将其L-函数与Eisenstein-Kronecker-Lerch级数明确地联系起来,从而验证了其L-函数满足的函数方程,以及它能在复平面上解析延拓的事实. 相似文献
2.
在一般BCH-代数(X,*,0)中,令x+y=0*((0*x)*y),证明了(X,+)是可换半群,称之为(X,*,0)的导出半群,给出了导出半群的性质,讨论了导出半群的理想与核,表明了BCH-代数与半群之间的关系. 相似文献
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人体运动仿真是虚拟现实领域新的研究热点,对X3D的相关知识进行了介绍,研究了利用Java平台和X3D技术实现人体运动的仿真。 相似文献
4.
仲彬草属和鹅观草属几个种的核型研究 总被引：1，自引：0，他引：1
本文报道了仲彬草属2个种和鹅观草属3个种的核型，其核型均为首次报道。结果如下：
Roegneria nutans，2n=4x=28=26m+2sm；R．abolinii，2n=4x=28=24m+4sm．R．aristiglumis，
2n=6x=42=32m+1Osm(2sat)；Kengyilia tahelacana，2n=6x=42=36m(2sat)+6sm(2sat)；K．
zhoasuensis，2n=6x=42=34m(4sat)+8sm．根据核型特征，K．tahelacana和K．zhoasuensis两个六位体种归入K.engyilia属是正确的。 相似文献
5.
三维地形可视化技术一直是地理信息系统、数字摄影测量、虚拟现实等领域的研究热点。介绍了X3D的相关知识,利用Java平台和X3D技术实现三维地形的可视化。 相似文献
6.
郭新弧 《中国科学院研究生院学报》1993,31(3):266-272
One new genus, one new species and one new subspecies of Labiatae
from Anhui and Zhejiang province of China are described and one new combina-
tion is made in this paper. They are Pogonanthera H. W. Li et X. H. Guo, P.
caulopteris H. W. Li et X. H. Guo, P. intermedia (C. Y. Wu et H. W. Li) H.
W. Li et X. H. Guo and Paraphlomis foliata (Dunn) C. Y. Wu et H. W. Lissp. montigena X. H. Guo et S. B. Zhou. 相似文献
7.
本文主要研究了X3D技术最具动态交互功能的Teuehsensor传感器，论述了在X3D虚拟三维扬景中，利用TouchSensor传感器实现动态交互的方法；以及结合实例，介绍了如何运用TouchSensor和EcmaScript语言建立动态交互场景，实现更强交互能力的方法。 相似文献
8.
在光学系统中,SOI(绝缘体上的半导体)上制备集成的MMI(多模干涉)型光耦合器已成为一种愈来愈引人注目的无源器件.由于Si和SiO2 之间具有大的折射率差,在SOI波导中可以采用SiO2 薄膜( <1.0 μm)作限制层,这与超大规模集成电路工艺相兼容.描述了采用SOI技术制备集成的MMI型光耦合器和光开关的设计和制造结果.业已证实,2× 2MMI MZI(多模干涉 麦赫 曾德干涉)型热光开关的开关时间小于 2 0 μs. 相似文献
9.
针对X3D虚拟场景的真实程度,从显示效果和文件大小角度研究烘焙技术在X3D虚拟场景中的应用,提出了在X3D虚拟场景中应用烘焙技术的操作方法,结合室内模型的地板烘焙实例阐述在建模、烘焙和导出X3D虚拟场景阶段的操作要点,验证了方法的可行性和有效性。 相似文献
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A. A. Momin M. P. Bankar G. M. Bhoite 《Indian journal of clinical biochemistry : IJCB》2016,31(3):286-293
Elevated plasma triglyceride and non-esterified fatty acid concentrations may cause insulin resistance and type 2 diabetes mellitus. Lipoprotein lipase (LPL) is a rate-determining enzyme in lipid metabolism. A variant in the LPL gene has been identified which alters the penultimate amino acid Serine at 447 to a stop codon (S447X), and results in a truncated LPL molecule lacking the C-terminal dipeptide Ser–Gly. The present study was designed to evaluate the frequency of S447X variant in the LPL gene and its effect on the lipid and lipoprotein levels in type 2 diabetic subjects. The genotype frequency distributions of type 2 diabetes patients and controls were in Hardy–Weinberg equilibrium. Comparison of the genotype and allelic frequencies of S447X in subjects with type 2 diabetics compared to controls demonstrated no significant difference. In subjects with type 2 diabetics having hypertriglyceridemia (TG ≥ 150 mg/dl) compared to diabetics with TG level <150 mg/dl, significant difference in genotype frequency was found among these groups, while allelic frequency of X was significantly differed. Logistic regression analysis showed the negative association of LPL S447X variant with TG and VLDL cholesterol, while no association with total cholesterol, HDL cholesterol and LDL cholesterol was found. The lipid levels except for HDL cholesterol were found to be significantly lower in carriers for S447X than wild type in diabetes group. The decreased level of TG and TG rich lipoprotein in subjects with SNP S447X in LPL, predicts anti-atherogenic activity of carriers for S447X variant in general population as well as type 2 diabetic patients. 相似文献
12.
螺旋理论认为，几乎所有的有机化合物结构中都存在螺旋，螺旋结构是导致旋光性的根本原因。左手螺旋左旋；右手螺旋右旋。化合物的总旋光方向是由分子结构中所有螺旋旋光度的代数和所决定。各种不同类型的化合物都遵从该理论。光学活性的环芃烷结构特殊，变化也很大。这类化合物构型规定中的P, M螺旋 ( plus or minus helix )，不是唯一的螺旋，也不一定都是旋光贡献最大的螺旋，应对其进行具体分析。只要仔细分析每一个化合物结构中存在的螺旋，就会发现，它们和其他类型的光学活性化合物一样，都遵从螺旋理论的规律。由化合物的绝对构型，可以预测其旋光方向；反之，由旋光方向可以推断其绝对构型。 相似文献
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Parvinder Kaur Sheenu Mathur Meenakshi Sharma Manisha Tiwari K. K. Srivastava Ramesh Chandra 《Indian journal of clinical biochemistry : IJCB》2001,16(2):195-198
In Ayurvedic medicine,Withania somnifera (Ashwagandha) is well known for its anti-stress activity. A passive rat experimental model, where the animals are subjected
to multiple stress of cold, hypoxia, restraint (C-H-R) has been developed to evaluate adaptogenic properties of various fractions
of W. somnifera root extracts. We have carried out extraction of roots of W. somnifera with water and further isolated one
of the active constituents called compound X and also tested its anti-stress activity in C-H-R model. The effect of administration
of W. somnifera water suspension (360 mg/Kg bw) and compound X (20mg/Kg bw) on the fall and recovery of colonic temperature
was noted. There was an increase of ≈38% and ≈54% in the time taken to attain Trec 23°C by rats given a single dose of fresh aqueous suspension and biologically active constituent (Compound X) respectively,
where as decrease in the recovery time to attain Trec 37°C is ≈13% and ≈33% respectively, as compared to control group. It is clear that rats treated with the fresh aqueous suspension
and compound X ofWithania somnifera, could withstand the multiple stress of C-H-R better than control group. 相似文献
15.
J.M. Lowerre 《Journal of The Franklin Institute》1977,303(6):517-526
For the linear statistical model y = Xb + e, X of full column rank estimates of b of the form (C + X′X)+X′y are studied, where C commutes with X′X and Q+ is the Moore-Penrose inverse of Q. Such estimators may have smaller mean square error, component by component than does the least squares estimator. It is shown that this class of estimators is equivalent to two apparently different classes considered by other authors. It is also shown that there is no C such that (C + X′X)+X′Y = My, in which My has the smallest mean square error, component by component. Two criteria, other than tmse, are suggested for selecting C. Each leads to an estimator independent of the unknown b and σ2. Subsequently, comparisons are made between estimators in which the C matrices are functions of a parameter k. Finally, it is shown for the no intercept model that standardizing, using a biased estimate for the transformed parameter vector, and retransforming to the original units yields an estimator with larger tmse than the least squares estimator. 相似文献
16.
Xujie Lü Constantinos Stoumpos Qingyang Hu Xuedan Ma Dongzhou Zhang Songhao Guo Justin Hoffman Kejun Bu Xiaofeng Guo Yingqi Wang Cheng Ji Haijie Chen Hongwu Xu Quanxi Jia Wenge Yang Mercouri G Kanatzidis Ho-Kwang Mao 《国家科学评论(英文版)》2021,8(9)
Metal halide perovskites possess unique atomic and electronic configurations that endow them with high defect tolerance and enable high-performance photovoltaics and optoelectronics. Perovskite light-emitting diodes have achieved an external quantum efficiency of over 20%. Despite tremendous progress, fundamental questions remain, such as how structural distortion affects the optical properties. Addressing their relationships is considerably challenging due to the scarcity of effective diagnostic tools during structural and property tuning as well as the limited tunability achievable by conventional methods. Here, using pressure and chemical methods to regulate the metal off-centering distortion, we demonstrate the giant tunability of photoluminescence (PL) in both the intensity (>20 times) and wavelength (>180 nm/GPa) in the highly distorted halide perovskites [CH3NH3GeI3, HC(NH2)2GeI3, and CsGeI3]. Using advanced in situ high-pressure probes and first-principles calculations, we quantitatively reveal a universal relationship whereby regulating the level of off-centering distortion towards 0.2 leads to the best PL performance in the halide perovskites. By applying this principle, intense PL can still be induced by substituting CH3NH3+ with Cs+ to control the distortion in (CH3NH3)1-xCsxGeI3, where the chemical substitution plays a similar role as external pressure. The compression of a fully substituted sample of CsGeI3 further tunes the distortion to the optimal value at 0.7 GPa, which maximizes the emission with a 10-fold enhancement. This work not only demonstrates a quantitative relationship between structural distortion and PL property of the halide perovskites but also illustrates the use of knowledge gained from high-pressure research to achieve the desired properties by ambient methods. 相似文献
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根据熊彼特关于"创新是‘新的生产函数的建立’,即‘企业家对生产要素之新的整合’"这一经典定义,构建了创新绩效函数W_i=F_i(X_1,X_2,……X_n),其中(X_1,X_2,……X_n)为企业拥有的n个创新要素,W_i为创新绩效。本文研究(1)发现在创新绩效函数中,F_i为(X_1,X_2,……X_n)的整合方式,表示在企业各种创新要素保持不变的情况下,只对这些要素进行不同整合就会为企业带来不同创新绩效,而技术创新模式正是对创新要素进行整合的方式,因此F_i即是技术创新模式。(2)提出如何选择企业最优技术创新模式的原理,即在企业(X_1,X_2,……X_n)不变条件下,能为企业带来最大创新绩效W~*的技术创新模式,就是该企业最优技术创新模式F~*_i。由于F~*_i具体关系式不易清晰界定,故本文将F~*_i的求解过程视为一个黑箱,对其进行了整体拟合。(3)根据最优创新模式选择原理,在建立并评价X、Y、Z、W、F_i的基础上,构建了企业最优技术创新模式选择模型。(4)收集川酒企业样本数据,实证分析川酒企业最优技术创新模式选择过程。 相似文献
19.
沈显生 《中国科学院研究生院学报》1989,27(4):304-305
One new species of the genus Vitis (Vitaceae) is described from Anhui
Province, China. It is vitis jinzhainensis X. S. Shen. 相似文献
20.
本文介绍了在我国浙江黄岩市首次发现上侏罗纪西山头组（J3x）地层中的硅化木。硅化木位于黄岩城西南约12km的大魏头山的火山岩地区，具体岩性为英安质晶屑玻屑凝灰岩，硅化木顺层呈似层状、透状、镶嵌状，平卧在凝灰岩层中，它与浙江新昌发现的硅化木有着重大区别。（1）前者产出层位是陆相火山爆发相的凝灰岩，后者是河湖相沉积岩；（2）前者是晚侏罗世，后者是早白垩世，前者要比后者早5～6千万年；（3）前者成因机理相对复杂。黄岩硅化木的发现为侏罗世时期大型植物化石提供了新材料，对这一时期地层古生物、古生态研究提供了重要实物证据，为侏罗世地质研究提供了基础。 相似文献