真核生物mRNA折叠结构与生物功能的理论研究

简要介绍和评述了ＲＮＡ折叠结构（主要是ＲＮＡ二级结构）的理论方法,对以ＲＮＡ二级结构为基础ＲＮＡ三级结构的构建方法和分子力学进行了初步探索和研究。真核细胞前体ｍＲＮＡ中内含子的剪接过程小及剪接位点（内含子的５′,３′,剪接位点和分枝点）的核苷序列与一些小蛋白质分子之间特定的专一相互作用,对大量的含子,外显子－内含子－外显子以及外显子－外显子的核苷酸片段二级结构的分析表明,剪接位点大多位于二级结构的     

P53蛋白质的末端二极结构预测及核心区点突变模拟研究

根据刘次全研究员等发现的蛋白质与其编码mＲＮＡ二级结构之间可能存在着二级结构单元 数目间的对应关系,首次深度参照Ｐ５３蛋白质Ｎ／Ｃ编码mＲＮＡ二级结构预测Ｐ５３蛋 白质Ｎ／Ｃ末端相应的二级结构。预测结果显示,在Ｐ５３蛋白质Ｎ端１－９３残基肽段可能存在四个α螺旋结构（１４－２６,３８－４６,５１－５６,６８－７０aa）。在Ｐ５３蛋白质Ｃ端单体聚合区以后的区域可能存在另外两个α螺旋（３６８－３７３,３８１－     

利用IRC进行国际天文遥在观测

１９９７年３月６日至３月７日,我们利用ＩＮＴＥＲＮＥＴＲＥＬＡＹＣＨＡＴ（ＩＲＣ）进行了首次国际天文联合遥在观测试验,并获得了成功。本次试验由分布在全球７个不同地点的工作组联合进行,包括中国、美国、加拿大和英国。这一试验的成功为天文观测开创了一个新型的途径,也是对通过Ｉｎｔｅｒ－ｎｅｔ进行更紧密的国际合作的一种尝试。     

OMC--3的13CO(1--0)和C18O(1--0)分子辐射

利用紫金山天文台青海站的 １３．７ ｍ毫米波望远镜,对 Ｏｒｉｏｎ Ａ分子云中的 ＯＭＣ－３区域,进行了较高分辨率的１３ＣＯ（Ｊ＝１－０）和Ｃ１８Ｏ（Ｊ＝１－０）分子辐射的成图观测．给出了该分子云中１３ＣＯ和 Ｃ１８Ｏ云核分布的整体结构和平均物理参数．观测发现,该分子云的１３ＣＯ和 Ｃ１８Ｏ的云核中心分别与最年轻的天体－Ｃｌａｓｓ ０类源 ＭＭＳＩ, ＭＭＳ４,ＭＭＳ６和ＭＭＳ７,ＭＭＳ８;ＭＭＳ９成协．此外,通过分析ＯＭＣ－３整个区域的速度场结构,发现沿 Ｃ１８Ｏ和１３ＣＯ云核方向从南到北有一个～ １．７ｋｍ／ｓ的速度场梯度,而分子云的红、蓝移团块则分别趋于云的北部和南部．并对ＯＭＣ－３区的恒星形成特征进行了讨论．     

7个新近发现的与分子外流成协的H_2O脉泽

本文发表继探测到恒星形成区的１０个新Ｈ２Ｏ脉泽［１］后，再发现和证认的７个银河系星际Ｈ２Ｏ脉泽及其有关参量和谱线图。这些新Ｈ２Ｏ脉泽是与ＣＯ分子外流源［２－５］ＡＦＧＬ５１４２，ＨＨ－３，ＡＦＯＬ５１５７，ＮＧＣ２０２３，ＲＮＯ７３，２０１２６＋４１０４，Ｌ１２５１－Ａ成协的。它们与相应的外向流的中心ＩＲＡＳ点源间的平均位置差为｜△α｜＝２４＇＇．８，｜△δ｜＝２７＇＇。     

OMC—3的^13CO（1—0）和C^18O（1—0）分子辐射

利用紫金山天台青海站的１３．７ｍ毫米波望远镜,对ＯｒｉｏｎＡ分子云中的ＯＭＣ－３区域,进行了较高分辨率的＾１３ＣＯ（Ｊ＝１－０）和Ｃ＾１８Ｏ（Ｊ＝１－０）分子辐射的图观测,给出了该分子云中＾１３ＣＯ和Ｃ＾１８Ｏ的云核中心分别与最年龄的天体－Ｃｌａｓｓ０类源ＭＭＳＩ,ＭＭＳ４,ＭＭＳ６和ＭＭＳ７,ＭＭＳ８,ＭＭＳ９成协,此外,通过分析ＯＭＣ－３整个区域的速度场结构,发现沿Ｃ＾１８Ｏ和＾１３ＣＯ云核     

Cyg X—1 X辐射的功率谱

运用自回归功率普研究Ｃｙｇ Ｘ－１ Ｘ辐射的频谱特征,结果显示Ｃｙｇ Ｘ－１转换态和高／软态时变频谱的连续成分,可以统一由有截断的幂律的成分描述,转换态存在小地３ＨＺ的宽峰结构及准周期振荡（ＱＰＯ）成分（４－１２ＨＺ）,而高／软态完全可由截断幂律普描述,不存在显著的ＱＰＯ。截断频率在各态相相当,在不同态的演化与平流为主的吸积流模型（ＡＤＡＦ（预期的情形一致。本文结果表明,自回归功率 研究Ｘ射线双     

活动星系统大蓝包的峰值在1050A附近吗？

对中小红移不同光度ＡＧＮ的大蓝包位置进行了统计检验,主要统计方法是对比软Ｘ射线波段谱指数（αｓｘ）分布与“直线”连接紫外１０５０Ａ和软Ｘ射线０．５ｋｅＶ的幂指数（αｕｖ－ｓｚ）分布,经过平均值统计和Ｋ－Ｓ检验,表明二分布是类似的。因此,在１０５０Ａ至０．５ｋｅＶ中可能是幂律谱,统计预言大蓝包峰值在１０５０Ａ附近,这个统计结果在软Ｘ选低光度ＡＧＮ样本（ＷＦ９３）上亦能得到,这表明ＷＦ９３样品尽管普     

P53蛋白质的末端二极结构预测及核心区点突变模拟研究

根据刘次全研究员等发现的蛋白质与其编码mRNA二级结构之间可能存在着二级结构单元数目间的对应关系 ,首次尝试参照P53蛋白质N/C末端的编码mRNA二级结构预测P53蛋白质N/C末端相应的二级结构。预测结果显示 ,在P53蛋白质N端 1 -93残基肽段可能存在四个α螺旋结构 (1 4-2 6 ,38-4 6 ,51 -56 ,6 8-70aa)。在P53蛋白质C端单体聚合区以后的区域可能存在另外两个α螺旋 (36 8-373,381 -388aa)。在P53蛋白质N/C端末知二级结构的预测区域内没有发现β层片结构。这些预测结果与法国蛋白质生物和化学研究所 (IBCP)多重序列联配蛋白质二级结构预测方法对照 (其准确率为 73.2 0 %左右 ) ,结果基本一致。在此工作基础上 ,将P53蛋白质N/C端预测的二级结构在SGI-INDIGO2 工作站上分别构建出三维构象模型。与分子生物学研究的资料对照 ,这两个模型较好的解释了P53蛋白质N/C末端特定的生物功能在三维结构上的相应特点。此外 ,在SGI -INDIGO2 工作站上 ,首次选择和利用P53蛋白质突变研究近十年积累的大量资料 ,以及P53蛋白质核心区三维晶体结构数据资料 ,对Arg1 75,Arg 2 49,和Arg 2 48三个P53蛋白质高频率突变点的十种不同的残基替换做了分子动力学研究。结果发现 ,P53蛋白质核心区在经历 1 2 ps的分子动力学过程后 ,其三     

富氧AGB星在银河系中的分布

根据ｖａｎｄｅｒＶｅｅｎ（１９８８）划分的ＩＲＡＳＰＳＣ的ＩＲＡＳ双色图区域选择了一批富氧ＡＧＢ星的样本，对其银河系分布进行的分析表明：它们属于盘星系，主要分布在旋臂上，将其旋臂结构与已知的ＨＩＩ区的旋臂结构进行拟合，得到这批富氧ＡＧＢ星的平均光度为８３００Ｌ⊙（Ｒｏ＝８．０ｋｐｃ），     

On the theory of the oblateness of the Sun

In this paper we first emphasize why it is important to know the successive zonal harmonics of the Sun's figure with high accuracy: mainly fundamental astrometry, helioseismology, planetary motions and relativistic effects. Then we briefly comment why the Sun appears oblate, going back to primitive definitions in order to underline some discrepancies in theories and to emphasize again the relevant hypotheses. We propose a new theoretical approach entirely based on an expansion in terms of Legendre's functions, including the differential rotation of the Sun at the surface. This permits linking the two first spherical harmonic coefficients (J ₂ and J ₄) with the geometric parameters that can be measured on the Sun (equatorial and polar radii). We emphasize the difficulties in inferring gravitational oblateness from visual measurements of the geometric oblateness, and more generally a dynamical flattening. Results are given for different observed rotational laws. It is shown that the surface oblateness is surely upper bounded by 11 milliarcsecond. As a consequence of the observed surface and sub-surface differential rotation laws, we deduce a measure of the two first gravitational harmonics, the quadrupole and the octopole moment of the Sun: J ₂=−(6.13±2.52)×10⁻⁷ if all observed data are taken into account, and respectively, J ₂=−(6.84±3.75)×10⁻⁷ if only sunspot data are considered, and J ₂=−(3.49±1.86)×10⁻⁷ in the case of helioseismic data alone. The value deduced from all available data for the octopole is: J ₄=(2.8±2.1)×10⁻¹². These values are compared to some others found in the literature. Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1005238718479     

Accounting for the viscosity of the fluid core in the problem of the physical libration of the moon

A two-component theoretical model of the physical libration of the Moon in longitude is constructed with account taken of the viscosity of the core. In the new version, a hydrodynamic problem of motion of a fluid filling a solid rotating shell is solved. It is found that surfaces of equal angular velocity are spherical, and a velocity field of the fluid core of the Moon is described by elementary functions. A distribution of the internal pressure in the core is found. An angular momentum exchange between the fluid core and solid mantle is described by a third-order differential equation with a right-hand side. The roots of a characteristic equation are studied and the stability of rotation is proved. A libration angle as a function of time is found using the derived solution of the differential equation. Limiting cases of infinitely large and infinitely small viscosity are considered and an effect of lag of a libration phase from a phase of action of an external moment of forces is ascertained. This makes it possible to estimate the viscosity and sizes of the lunar fluid core from data of observations.     

Calculation of the global system of the field-aligned currents on the dayside of the magnetosphere

Using the well-known equation for the normal component of the current which exist near the tangential discontinuity in the plasma in the case of the frozen-in magnetic field, and supposing that the current closes in the ionosphere in the auroral oval in the region 1, one calculates and compares with the data of observations the dependence of the density of the field-aligned current at the level of the ionosphere on the local time.     

Rotation of the elastic Earth: the role of the angular-velocity-dependence of the elasticity-caused perturbation

We calculate the so-called convective term, which shows up in the expression for the angular velocity of the elastic Earth, within the Andoyer formalism. The term emerges due to the fact that the elasticity-caused perturbation depends not only on the instantaneous orientation of the Earth but also on its instantaneous angular velocity. We demonstrate that this term makes a considerable contribution into the overall angular velocity. At the same time the convective term turns out to be automatically included into the correction to the nutation series due to the elasticity, if the series is defined by the perturbation of the figure axis (and not of the rotational axis) in accordance with the current IAU resolution. Hence it is not necessary to take the effect of the convective term into consideration in the perturbation of the elastic Earth as far as the nutation is related to the motion of the figure axis.     

Impact of the Quadrupole Moment of the Sun on the Dynamics of the Earth-Moon System

Range of values of the Sun's mass quadrupole moment of coefficient J₂ arising both from experimental and theoretical determinations enlarge across literature on two orders of magnitude, from around 10^-7 until to 10^-5. The accurate knowledge of the Moon's physical librations, for which the Lunar Laser Ranging data reach an outstanding precision level, prove to be appropriate to reduce the interval of J₂ values by giving an upper bound of J₂. A solar quadrupole moment as high as 1.1 10^-5 given either from the upper bounds of the error bars of the observations, or from the Roche's theory, is not compatible with the knowledge of the lunar librations accurately modeled and observed with the LLR experiment. The suitable values of J₂ have to be smaller than 3.0 10^-6. As a consequence, this upper bound of 3.0 10^-6 is accepted to study the impact of the Sun's quadrupole moment of mass on the dynamics of the Earth-Moon system. Such as effect (with J₂ = 5.5±1.3 × 10^-6) has been already tested in 1983 by Campbell & Moffat using analytical approximate equations, and thus for the orbits of Mercury, Venus, the Earth and Icarus. The approximate equations are no longer sufficient compared with present observational data and exact equations are required. As if to compute the effect on the lunar librations, we have used our BJV relativistic model of solar system integration including the spin-orbit coupled motion of the Moon. The model is solved by numerical integration. The BJV model stems from general relativity by using the DSX formalism for purposes of celestial mechanics when it is about to deal with a system of n extended, weakly self-gravitating, rotating and deformable bodies in mutual interactions. The resulting effects on the orbital elements of the Earth have been computed and plotted over 160 and 1600 years. The impact of the quadrupole moment of the Sun on the Earth's orbital motion is mainly characterized by variations of , , and . As a consequence, the Sun's quadrupole moment of mass could play a sensible role over long time periods of integration of solar system models. This revised version was published online in July 2006 with corrections to the Cover Date.     

On the role of the motion of the photospheric footpoints of the magnetic field lines

By means of a simple relation between the velocity v of the fluid particle and the velocity v_f of the photospheric footpoint of the magnetic field line v_z and B_z being respectively the components of v and the magnetic field B normal to the photospheric surface, it is shown formally that through the phtospheric surface the transport of all the quantities attributed to the magnetic field, such as the magnetic flux, the magnetic energy and the helicity, is independent of v_z, and v_f is the only kinematical quantity on which the transport depends. In addition, in the neighborhood of the neutral line the velocity v_l of the moving curve of constant B_z is found to be equal approximately to the component of v or v_f in the direction of v_l. Since v_l can be measured or extimated, so can the components of v and v_f near the neutral line.     

Determination of the temperature of the solar corona from the spectrum of the electron-scattering continuum

When the K-corona is formed by the scattering of photospheric radiation from free electrons, the Fraunhofer lines are greatly broadened by the thermal motions of the hot electrons. This paper discusses the possibility of measuring the coronal electron temperature from the residual depressions in the K-coronal spectrum. If the ratio of the intensities at 4100 Å and 3900 Å can be measured to an accuracy of ±1%, the coronal temperature can be inferred to an accuracy of ±0.2 MK. The temperature of a coronal inhomogeneity may also be measured by this method, provided the position angle is known.Now at Fraunhofer Institute, Freiburg, Germany.     

On the systematic errors of the determinations of the absolute orientation of the meridian marks

The classical method of determination of the absolute azimuth (or Bessel's parameter n) can secure sufficiently precision for RA from observations of stars at high geographical latitudes during polar night only.