饮水的科学

水不但具有对营养物的消化、吸收、输送的功能,还起着调节体温、润滑脏器的作用,所以水在人的生命中极为重要.饮水要注意科学:1.要定时,劳动或激烈运动出汗过多时,水中适当加些食盐,以补充钠、钾离子的散失,维持体内电解质的平衡.2.养成早晨起床后饮水的好习惯.3.饮用的水应是一次性烧开的新鲜水.4.饮水时最好是空腹.5.切忌暴饮.6.饮水时要注意水温,不能太凉或太热.     

寄生于北京地区的驴的圆形线虫报告Ⅱ.包括一新种的叙述

本文报告了寄生于北京地区的驴的圆形线虫8种,分属于两个属;内包括一新种的叙述。即Trichonema labratum,T.labiatum,T.labiatum var.digitatum,T.coronatum,T.longibursatum,T.minutum,Trichonema tsengi sp.nov.和Petrovinema poculatum。     

安徽的新植物

Phyllanthus leptocladus Benth. var. pubescens P. T. Li et D. Y. Liu, var. nov. A typo differt fructibus pubescentibus. Anhui (安徽):Liugu Jian (六股尖), D. Y. Liu (刘登义)0440, 0911, 0998(Type, in Herb. Biol. Depart. Anhui NormalUniv.)本变种与原变种的主要区别在于果被短柔毛。     

假地枫皮的订正

作者查阅了全国42个标本馆所收藏的403号假地枫皮Illicium jiadifengpi B.N.Chang标本, 确认该种植物为中国特有, 分布于安徽、浙江、江西、福建、湖北、湖南、广东和广西。将百山祖八角I.jiadifengpi B.N.Changvar.baishanense B.N.Chang et S.H.Ou归并到假地枫皮;将闽皖八角I.minwanense B.N.Changet S.D.Zheng作为假地枫皮的一个变型--紫花八角I.jiadifengpi B.N.Changf.minwanense(B.N.ChangetS.D.Zhang)Q.Lin, 将武夷八角I.wuyishanum Q.Lin归并到紫花八角中。     

聚赖氨酸和它的溴化氢结合物结构变化的红外光谱研究

聚赖氨酸(PLys)和它的溴化氢结合物(PLys-HBr)在不同的相对湿度(R.H.)下,用红外光谱仪测得它们的结构变化.固态PLys-HBr(平均分子量(MW)55000)在40%R.H.以下能保持无规卷曲结构,在40—70%R.H.之间为β-折叠,70%R.H.以上为α-螺旋.PLys由于它们的平均分子量不同,结构变化差别较大.PLys(MW 55000)在各种相对湿度下保持α-螺旋,直至96%R.H.才出现β-折叠.PLys(MW 14000)在40%R.H.以下能保持无规卷曲结构,在40—85%R.H.之间主要为β-折叠,85%R.H.以上为α-螺旋.     

呼吸的调节

在动物和人的机体中,进行着各种各样的和极其复杂的生理过程。在这一切生理过程中,呼吸起着很重要的作用。很多最卓越的、国内的学者们:И.М.谢切诺夫(Сеченов)、Н.А.米斯拉夫斯基(Миславский)、В.М.别赫切列夫(Бехтерев)、Н.Е.维金斯基(Введенский) 都曾从事过呼吸的研究。现时,这个问题在К.М.贝柯夫(Быков)、Д.А.毕留科夫(Бирюков)、А.И.斯米尔诺夫(Смирнов)、М.Е、马尔沙克(Маршак)     

荩草属的新分类等级

本文报导荩草属Arthraxon Beauv.中4新组,4新种,2新变种,即小叶荩草组Sect.Microarthraxon S.L.Chen et Y.X.Jin,三蕊荩草组Sect.Triandroarthraxon S.L.Chen et Y.X.Jin,无篦齿组Sect.Monostrichi S.L.Chen et Y.X.Jin,篦齿组Sect.Tristrichi S.L.Chenet Y.X.Jin,多脉荩草A.multinervus S.L.Chen et Y.X.Jin,茅坪荩草A.maopingensis S.L.Chen et Y.X.Jin,贵州荩草A.guizhouensisS.L.Chen et Y.X.Jin,西南荩草A.xinanensis S.L.Chen et Y.X.Jin,疏序荩草A.xinanensis var.laxiflorus S.L.Chen et Y.X.Jin及光轴荩草A.lanceolatus var.glabrous S.L.Chen et Y.X.Jin.     

新疆的芍药属

产于我国新疆的芍药属Paeonia L.植物虽然种类不多,但分类上却一直未予澄清。按《FL.URSS》(Tom.7)有两种,P.anomala L.和P.hybrida Pall.,按Stern(1946)有一种,包括两个变种,即P.anomala L.和P.anomala var.intermedia(C.A.     

牙形刺的鉴定与乐平统的底界

Clarkina postbitteri和C.dukouensis两个种的正确鉴定是确定乐平统底界的关键.Mei和Wardlaw(1994b,c)在建立这两个种时就已明确指出,C.postbitteri不同于C.dukouensis主要是有浑圆而不是钝圆的齿台后端,并有明显的后边缘(brim),并不是依据齿脊特征区别的.金玉 (Jin,2000a)与Henderson(2001)强调,C.postbitteri的中后部细齿分离是有别于C.dukouensis的主要特征.比较C.postbitteri与C.dukouensis的正模和Mei et al .(1 994c)所鉴定的C.dukouensis(图la-c),可以清楚地看到,两者的齿脊几乎相同.Mei et al .(1994c)所鉴定的C.dukouensis齿脊的细齿甚至比C.postbitteri的还分离(图1a,b).两个种的区别,应保持原来的定义主要依齿台后端形状和后边缘的有无. Clarkina dukouensis由C.postbitteri逐渐过渡而来,Henderson(2001)认为,由于是逐渐过渡,C.dukouensis首次出现的点位就是任意选择的.然而,泥盆系一石炭系界线的定义是在Siphonodella presulcata-S.sulcata连续演化谱系中S.sulcata的首次出现,无人认为,由于是连续演化谱系这个界线点位就是任意的.所有泥盆系的阶的金钉子都是以祖先种到定义种的演化谱系中定义种的首次出现为定义的,也无人认为这些金钉子的点位是任意的,因为每个阶的定义种都有明确的定义.C.dukouensis也有明确的定义,只要齿台后端变钝圆,后边缘消失,就由C.postbitteri进化到C.dukouensis.这个位置就在LPD115-6k,并非可任意选择. 金玉开(Jin,2000a),Henderson(2001)指出,他们对种的鉴定采用了居群概念.在确定金钉子点位时,必须考虑定义种在首次出现(FAD)时的居群特征,这就是a.个体很少;b.形态类型单调;c与先驱种共存;d.在几个剖面上可以证实.LPD115-6k中的C.dukouensis个体很少,形态单调,与先驱种C.postbitteri共存,完全具有此种早期居群的特征.相反,在LPD115 6j和6i上部的C.postbitteri个体数量多,形态类型多样,含有自C. postbitteri到C.dukouensis的过渡类型,代表C.postbitteri演化谱系的高级阶段,反映此种中晚期的居群特征.同时,不能扩大居群的概念,不能把不同的种包括到同一居群中去.金玉 (Jin,2000a)和Henderson(2001)认为C.dukouensis在LPD11 4-7e才开始出现,笔者认为,他们将LPD114-7b中的典型的Clarkina leveni,C.niuzhuanensis,C.bizarrensis也不恰当地归入Clarkina postbitteri居群中.LPD114-7b应属C.leveni带. Henderson(2001)强调,Jinogondolella granti是C.postbitteri的祖先,两者没有重叠,形态差别大.金玉 (Jin,2000a)和Henderson(2001)用点断平衡演化来解释这一差别.但真正的点断平衡演化都有先驱种和后继种的重叠,新的分子不是在先驱分子消失后才出现的,而是在一定的时限内与先驱种共存,并且都是在连续的地层中出现的.没有证实的点断平衡事件,从来不用来做GSSP的建立依据.国际地层规范强调的是,GSSP要建立在连续的地层中,定义种必须有清楚的演化关系.没有任何形态上的证据可以证明C.postbitteri是由Jinogondollella granti演化而来. Henderson(2001)还强调,LPD115-6i上下之间有一小间断(diastem),这一界线是一层序界线,是最理想的乐平统的底界.但小间断的存在,正表明这是一条不理想的生物地层界线,因为根据国际地层规范,GSSP必须建立在连续的单一岩相的地层中.层序地层界线不适合建立GSSP,因为所有层序地层界线都意味着可能有间断.最理想的生物地层界线是在层序界面或初始海泛面之上的第一广泛分布的生物带的底界(Wang&Su,2000).C.dukouen-sis正是这样的生物带,它比层序地层界线高21cm,比岩石地层界线低21cm.层序地层界线是非常好的辅助参考标准,但不是统或阶的界线本身.     

时滞Nicholson＇s Blowflies方程中行波解的Hopf分支

主要利用时滞微分方程中Hopf分支理论探讨时滞Nicholson＇s Blowflies方程中行波解随时滞量τ大小变化的分支行为.结果发现时滞量经过某一数值τ_0=1/（cω_0） arcsin-cω_0/p时,原系统会产生分支现象,最终导致形成周期性行波解.     

Non-Linear Bifurcation Analysis of Reaction-Diffusion Activator-Inhibator System

The paper first deals with the linear stability analysis of an activator-inhibitor reaction diffusion system to determine the nature of the bifurcation point of the system. The non-linear bifurcation analysis determining the steady state solution beyond the critical point enables us to determine characteristic features of the spatial inhomogeneous pattern formation arising out of the bifurcation of the state of the system.     

The prey-dependent consumption two-prey one-predator models with stage structure for the predator and impulsive effects

In this paper, we consider the prey-dependent consumption two-prey one-predator models with stage structure for the predator and impulsive effects. By applying the Floquet theory of linear periodic impulsive equation, we show that there exists a globally asymptotically stable pest-eradication periodic solution when the impulsive period is less than some critical value, that is, the pest population can be eradicated totally. But from the point of ecological balance and saving resources, we only need to control the pest population under the economic threshold level instead of eradicating it totally, and thus, we further prove that the system is uniformly permanent if the impulsive period is larger than some critical value, and meanwhile we also give the conditions for the extinction of one of the two preys and permanence of the remaining species. Thus, we can use the stability of the positive periodic solution and its period to control insect pests at acceptably low levels. Considering population communities always are imbedded in periodically varying environments, and the parameters in ecosystem models may oscillate simultaneously with the periodically varying environments, we add a forcing term into the prey population's intrinsic growth rate. The resulting bifurcation diagrams show that with the varying of parameters, the system experiences process of cycles, periodic windows, periodic-doubling cascade, symmetry breaking bifurcation as well as chaos.     

Understanding bursting oscillations as periodic slow passages through bifurcation and limit points

We consider a biochemical system consisting of two allosteric enzyme reactions coupled in series. The system has been modeled by Decroly and Goldbeter (J. Theor. Biol. 124, 219 (1987)) and is described by three coupled, first-order, nonlinear, differential equations. Bursting oscillations correspond to a succession of alternating active and silent phases. The active phase is characterized by rapid oscillations while the silent phase is a period of quiescence. We propose an asymptotic analysis of the differential equations which is based on the limit of large allosteric constants. This analysis allows us to construct a time-periodic bursting solution. This solution is jumping periodically between a slowly varying steady state and a slowly varying oscillatory state. Each jump follows a slow passage through a bifurcation or limit point which we analyze in detail. Of particular interest is the slow passage through a supercritical Hopf bifurcation. The transition is from an oscillatory solution to a steady state solution. We show that the transition is delayed considerably and characterize this delay by estimating the amplitude of the oscillations at the Hopf bifurcation point.     

一类食饵捕食系统的Hopf分岔及周期解的稳定性

首先建立了具有时滞的三种群食饵捕食模型,并研究了平衡点的存在性,接着应用规范化方法和中心流行定理研究了Hopf分岔以及分岔周期解的稳定性.并举例论证.     

Birfurcation theory applied to a simple model of a biochemical oscillator

Some results are presented relating to the question whether self-sustained oscillations are possible in a sequence of biochemical reactions with end- point inhibition. The model used has a single nonlinear ordinary differential equation coupled to a set of linear equations, with all coefficients in the linear terms equal. The explicit algebraic form of the Hopf-Friedrich bifurcation theory is used to show that when the number of coupled equations is large enough this model has a stable periodic solution when the equilibrium point of the equations has just become unstable.     

Phase resetting and bifurcation in the ventricular myocardium.

With the dynamic differential equations of Beeler, G. W., and H. Reuter (1977, J. Physiol. [Lond.]. 268:177-210), we have studied the oscillatory behavior of the ventricular muscle fiber stimulated by a depolarizing applied current I app. The dynamic solutions of BR equations revealed that as I app increases, a periodic repetitive spiking mode appears above the subthreshold I app, which transforms to a periodic spiking-bursting mode of oscillations, and finally to chaos near the suprathreshold I app (i.e., near the termination of the periodic state). Phase resetting and annihilation of repetitive firing in the ventricular myocardium were demonstrated by a brief current pulse of the proper magnitude applied at the proper phase. These phenomena were further examined by a bifurcation analysis. A bifurcation diagram constructed as a function of I app revealed the existence of a stable periodic solution for a certain range of current values. Two Hopf bifurcation points exist in the solution, one just above the lower periodic limit point and the other substantially below the upper periodic limit point. Between each periodic limit point and the Hopf bifurcation, the cell exhibited the coexistence of two different stable modes of operation; the oscillatory repetitive firing state and the time-independent steady state. As in the Hodgkin-Huxley case, there was a low amplitude unstable periodic state, which separates the domain of the stable periodic state from the stable steady state. Thus, in support of the dynamic perturbation methods, the bifurcation diagram of the BR equation predicts the region where instantaneous perturbations, such as brief current pulses, can send the stable repetitive rhythmic state into the stable steady state.     

Some analytical results about a simple reaction-diffusion system for morphogenesis

Summary The reaction-diffusion system considered involves only one nonlinear term and is a gradient system. In a bifurcation analysis for the equilibrium states, the global existence of infinitely many solution branches can be shown by the method of Ljusternik-Schnirelmann. Their stability is studied. Using a Ljapunov functional it can be shown that the solutions of the time-dependent system converge to the equilibrium states.     

General solution of cable theory with both ends sealed

General solution of the cable theory with both ends sealed when injecting an arbitrary current at an arbitrary point of the cable is presented, which is a time-dependent transient solution. The solution is an infinite series, each term of which is the product of a cosine term including a position variable only and an exponential term including a time variable only. The general solution contains almost all solutions reported hitherto as particular cases and the mutual relations among the various solutions of quite different forms are clarified by this general solution. Moreover the shorter the cable becomes, the more rapidly this solution converges, therefore it is useful for an analysis of the short cable in the case where the relative deviation error may grow large. The truncation error can also be estimated as the solution is an infinite series of simple functions.     

Bifurcation and resonance in a model for bursting nerve cells

In this paper we consider a model for the phenomenon of bursting in nerve cells. Experimental evidence indicates that this phenomenon is due to the interaction of multiple conductances with very different kinetics, and the model incorporates this evidence. As a parameter is varied the model undergoes a transition between two oscillatory waveforms; a corresponding transition is observed experimentally. After establishing the periodicity of the subcritical oscillatory solution, the nature of the transition is studied. It is found to be a resonance bifurcation, with the solution branching at the critical point to another periodic solution of the same period. Using this result a comparison is made between the model and experimental observations. The model is found to predict and allow an interpretation of these observations.