The contribution of root respiration to soil CO2 efflux in Puccinellia tenuiflora dominated community in a semi-arid meadow steppe

Rising atmospheric CO2 and temperature are altering ecosystem carbon cycling. Grasslands play an important role in regional climate change and global carbon cycle. Below-ground processes play a key role in the grassland carbon cycle because they regulate …     

独活属药用部位的解剖学研究

对四川独活属13种植物进行了解剖学研究，根据独活属植物根的次生韧皮部远比次生木质部发达的特点，确定独活属植物的根是典型的贮藏型根，研究结果表明：分泌道存在于中柱鞘和次生韧皮部，而不存在于次生木质部和周皮，根部分泌道的数量与药用价值相关。接受独活属植物中分泌道丰富的独活H．hemsleyanum、短毛独活H．moellendorffii、平截独活H．vincinum、自亮独活H．candicans、永宁独活H．yungningense等种为独活属主要的药用植物。     

从海带根中提取纯化褐藻硫酸多糖

海带根粉碎后，经过酶解，去除褐藻酸，得到酶解液；通过DE-41、DE-80离子交换柱层析，得到海带硫酸多糖(FGS)F1-F8的8种不同组分；再用Sepharose 2B凝胶柱层析纯化，获得层析纯F1-F8的FGS．我们初步测定了8种FGS的分子量、单糖组分及其摩尔比．FGS为一类含有鼠李糖、岩藻糖、木糖、甘露糖、半乳糖以及硫酸根的杂多糖．     

求解微分方程Y″＋ρy′＋qy=f（x）的注记

利用函数组线性相关性、微分方程降阶积分法和二阶微分方程解的结构性质，对二阶常系数非齐次线性微分方程求解问题作了进一步分析讨论，给出了求其通解的一种适用且有效的新方法．     

印度梨形孢对黑松幼苗生长量及其根系形态的动态影响

为研究印度梨形孢(Piriformospora indica)对黑松(Pinus thunbergii)幼苗生长及其根系形态的动态影响,在营养杯培育条件下研究了印度梨形孢对黑松地上部分与根系生长、根系构型及根系分形维数的影响。结果表明,印度梨形孢对黑松地下根系生长的促进作用发挥时间早于地上部分、效应显著高于地上部分,接种印度梨形孢15~30 d时对地上部分基本无影响,但对根系促进作用明显,而地上部分在60 d时生长效应显著。接种印度梨形孢可增加黑松地上部分、根系的生物量,也显著地改善了根系长度、分支数、表面积、体积等构型参数与根系分形维数,促进黑松生长。     

Proton Nuclear Magnetic Resonance Spectrometry-Based Metabolic Characterization of Panax Notoginseng Roots

The radix of Panax notoginseng is an important herbal resource for clinics, commercial markets, and the health industry worldwide. The quality of P. notoginseng roots is known to be associated with its cultivation age. This study used ¹H-nuclear-magnetic-resonance-spectrometry-based metabolic profiling to characterize P. notoginseng roots. Twenty metabolites—including four ginsenosides—contributed to the composition of P. notoginseng according to age. A partial least-squares regression model using a combined data set from two solvent systems was the best predictor of cultivation age. Finally, receiver-operating-characteristic analysis was used to screen potential markers of P. notoginseng root age. These results may be applied to the development of medicinal and nutraceutical products using P. notoginseng roots.     

Optimal feedback gains of a delayed proportional-derivative (PD) control for balancing an inverted pendulum

In the dynamics analysis and synthesis of a con-trolled system, it is important to know for what feedback gains can the controlled system decay to the demanded steady state as fast as possible. This article presents a sys-tematic method for finding the optimal feedback gains by taking the stability of an inverted pendulum system with a delayed proportional-derivative controller as an example. First, the condition for the existence and uniqueness of the stable region in the gain plane is obtained by using the D-subdivision method and the method of stability switch. Then the same procedure is used repeatedly to shrink the stable region by decreasing the real part of the rightmost charac-teristic root. Finally, the optimal feedback gains within the stable region that minimizes the real part of the rightmost root are expressed by an explicit formula. With the optimal feedback gains, the controlled inverted pendulum decays to its trivial equilibrium at the fastest speed when the initial val-ues around the origin are fixed. The main results are checked by numerical simulation.     

方差可能无穷的“中度偏离”单位根过程的复合分位数估计

考虑一类"中度偏离"单位根过程,y_t=q_ny_t-1+u_t,其中qn=1+c/(k_n),k_n=o(n),c为一非零常数,{u_t}为随机扰动项序列.在允许扰动项方差无穷的条件下,构造q_n的复合分位数估计,并得到了该估计的渐近分布.最后通过数值模拟,在扰动项服从t(2)分布下,说明了该估计的稳健和有效性.     

古巴比伦人求算术平方根的探究

分析了古巴比伦人求算术平方根的算法，证明了其正确性。然后将其算法推广到求n次算术根，并证明了其正确性。     

Non‐self‐adjoint singular second‐order dynamic operators on time scale

In this study, maximal dissipative second‐order dynamic operators on semi‐infinite time scale are studied in the Hilbert space , that the extensions of a minimal symmetric operator in limit‐point case. We construct a self‐adjoint dilation of the dissipative operator together with its incoming and outgoing spectral representations so that we can determine the scattering function of the dilation as stated in the scheme of Lax‐Phillips. Moreover, we construct a functional model of the dissipative operator and identify its characteristic function in terms of the Weyl‐Titchmarsh function of a self‐adjoint second‐order dynamic operator. Finally, we prove the theorems on completeness of the system of root functions of the dissipative and accumulative dynamic operators.