中国互联网:政府与企业合作的结晶——互联网发展12年的回顾与展望

在市场经济条件下,政府与企业各自的职能和目标是什么?在经济活动中各自扮演何种角色?二者的关系应怎样处理?通过分析中国互联网12年的发展过程,我们获得的教益是:政府为互联网的发展提供了法律和政策框架,企业是互联网发展的动力源泉,这种政企关系模型为国有企业的改革提供了重要借鉴。

π-π Stacking Force in the Solid Structure of Mixed-Metal Complexes: Zn(phen)_2MS_4 (M=W, Mo)

The inter-diffusion of N,N-dimethylformamide solution of Zn(phen)2Cl2 and (NH4)2MS4 (M = W, Mo) in an H-shape tube produced crystals of Zn(phen)2WS4 1 and Zn(phen)2MoS4 2 (phen = 1,10-phenanthroline). The structures of isomorphous complexes 1 and 2 have been determined by X-ray single-crystal structure analyses. Four nitrogen atoms from the phenanthroline ligands and two sulfur atoms from the MS42- anion forming a distorted octahedron coordinate each zinc atom. Through p-p interactions of adjacent aromatic rings of the phenanthroline ligands, a quasi one-dimensional zigzag-stacking column is formed in each complex. Complex 1 crystallizes in monoclinic space group C2/c, with a = 10.447(8), b = 22.016(9), c = 12.824(8) ? b = 103.56(6)? V = 2867.7(8) 3, Z = 4, C24H16N4S4WZn, Mr=737.90, Dc = 1.71 g/cm3, F(000) = 1424, m = 5.25 mm-1, the final R = 0.054 and Rw = 0.075 for 2315 observations with I > 3s (I). Complex 2 crystallizes in monoclinic space group C2/c, with a = 10.410(6), b = 22.095(7), c = 12.830(6) ? b = 103.19(8)? V = 2873.1(5) 3, Z = 4, C24H16MoN4S4Zn, Mr=649.99, Dc = 1.50 g/cm3, F(000) = 1296, m = 1.58 mm-1, the final R = 0.072 and Rw = 0.100 for 1631 observations with I > 3s(I).

Hydration effects on crystal structures and equations of state for silicate minerals in the subducting slabs and mantle transition zone

There are potentially huge amounts of water stored in Earth's mantle, and the water solubilities in the silicate minerals range from tens to thousands of part per minion(ppm, part per million). Exploring water in the mantle has attracted much attention from the societies of mineralogy and geophysics in recent years. In the subducting slab, serpentine breaks down at high temperature, generating a series of dense hydrous magnesium silicate(DHMS) phases, such as phase A, chondrodite, clinohumite, etc. These phases may serve as carriers of water as hydroxyl into the upper mantle and the mantle transition zone(MTZ). On the other hand, wadsleyite and ringwoodite, polymorphs of olivine, are most the abundant minerals in the MTZ, and able to absorb significant amount of water(up to about 3 wt.% H_2O). Hence, the MTZ becomes a very important layer for water storage in the mantle, and hydration plays important roles in physics and chemistry of the MTZ. In this paper, we will discuss two aspects of hydrous silicate minerals:(1) crystal structures and(2) equations of state(Eo Ss).

Construction of interesting organic supramolecular structures with synthons cooperation in the cocrystals of 1H-benzotriazole and hydroxybenzoic acids

Multifunctional molecules are capable of assembling via different supramolecular synthons, or hydrogen bond motifs, between the same or different functional groups, leading to the possibility of cocrystal. Utilization of the interplay of dimensionality （I-D, 2-D and 3-D）, orientation of functional groups of the building blocks, influence of rigid/flexible linking groups, and weak interactions provides an interesting route for the creation of novel supramolecular architectures in the crystal lattice. N-unsubstituted 1H-benzotriazole and carboxylic acid, being self-complementary molecules, offer a broad scope of study of binary compounds based on the complementary combination of H-bonding/donating sites. We report here the construction of three extended molecular networks in cocrystals of the carboxylic acid group of the acid and the 1H-benzotriazole triazole moiety. We have been able to identify four major supramolecualr synthons that would be helpful in the prediction of structural motifs for these kinds of studies. Interestingly, these heterosynthons are strikingly similar, to those of the homosynthons of the individual functional groups. The nature of the aza groups helps to enhance the overall volume of the crystal lattice thus lead- ing to the formation of various supramolecular assemblies. Thermal stability of these compounds has been investigated by thermogravimetric analysis （TGA） of mass loss.

Ferromagnetic interactions in EO-azido-bridged binuclear transition metal(Ⅱ) systems: Syntheses, crystal structures and magnetostructural correlations

Three new isostructural binuclear transition metal complexes with azido ion and 1,2-bis（3-（pyridin-2-yl）-lH-pyrazol-1- yl）ethane （bppe）, formulated as [M2（N3）2（bppe）2]（C104）2 （M = Co, 1; Ni, 2; Cu, 3）, were successfully synthesized. They were structurally and magnetically characterized. In 1-3, the double azido ions link two adjacent octahedral metal centers together in the end-to-on mode （EO）, with the M-NEo-M angles of 99.41°, 100.24° and 99.80°, respectively. The co-ligand bppe acts as terminal ligand to saturate the remaining coordination sites. The magnetic properties of 1-3 have been investigated in the tem- perature range of 2-300 K. Fitting of the magnetic susceptibility data revealed the occurrence of the strong ferromagnetic in- teractions [J = 26.32 cm-1 （1）, J = 38.23 cm-1 （2） and J = 139.83 cm-1 （3）]. Density functional theory calculations have been performed on 1-3 to provide a magneto-structural correlation of the ferromagnetic behavior.