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81.
Highly Strained Heterometallacycles of Group 4 Metallocenes with Bis(diphenylphosphino)amide Ligands
Martin Haehnel Sven Hansen Dr. Anke Spannenberg Dr. Perdita Arndt Dr. Torsten Beweries Prof. Dr. Uwe Rosenthal 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(34):10546-10553
A study regarding coordination chemistry of the bis(diphenylphosphino)amide ligand Ph2P‐N‐PPh2 at Group 4 metallocenes is presented herein. Coordination of N,N‐bis(diphenylphosphino)amine ( 1 ) to [(Cp2TiCl)2] (Cp=η5‐cyclopentadienyl) generated [Cp2Ti(Cl)P(Ph2)N(H)PPh2] ( 2 ). The heterometallacyclic complex [Cp2Ti(κ2‐P,P‐Ph2P‐N‐PPh2)] ( 3 Ti ) can be prepared by reaction of 2 with n‐butyllithium as well as from the reaction of the known titanocene–alkyne complex [Cp2Ti(η2‐Me3SiC2SiMe3)] with the amine 1 . Reactions of the lithium amide [(thf)3Li{N(PPh2)2}] with [Cp2MCl2] (M=Zr, Hf) yielded the corresponding zirconocene and hafnocene complexes [Cp2M(Cl){κ2‐N,P‐N(PPh2)2}] ( 4 Zr and 4 Hf ). Reduction of 4 Zr with magnesium gave the highly strained heterometallacycle [Cp2Zr(κ2‐P,P‐Ph2P‐N‐PPh2)] ( 3 Zr ). Complexes 2 , 3 Ti , 4 Hf , and 3 Zr were characterized by X‐ray crystallography. The structures and bondings of all complexes were investigated by DFT calculations. 相似文献
82.
采用溶胶凝胶法制备了h-k氧化铪HfO2薄膜, 经500℃退火后, 获得了高透过率、表面光滑、低漏电流和相对高介电常数的HfO2薄膜. 并采用氧化铪作为绝缘层和锌铟锡氧化物作为有源层成功地制备了底栅顶接触结构薄膜晶体管器件. 获得的薄膜晶体管器件的饱和迁移率大于100 cm2·V-1·s-1, 阈值电压为-0.5 V, 开关比为5×106, 亚阈值摆幅为105 mV/decade. 表明采用溶胶凝胶制备的薄膜晶体管具备高的迁移率, 其迁移率接近低温多晶硅薄膜晶体管的迁移率. 相似文献
83.
C. J. Powell W. S. M. Werner W. Smekal G. Tasneem 《Surface and interface analysis : SIA》2013,45(2):628-638
We have used the National Institute of Standards and Technology Database for the Simulation of Electron Spectra for Surface Analysis (SESSA) to simulate photoelectron intensities for thin films of SiO1.6N0.4 and HfO1.9N0.1 on silicon with excitation by Al Kα X‐rays. We considered Si 2p3/2 photoelectrons from SiO1.6N0.4 and the substrate and Hf 4f7/2 photoelectrons from HfO1.9N0.1. The simulations were performed for ranges of film thicknesses and photoelectron emission angles and for two common configurations for X‐ray photoelectron spectroscopy (XPS), the sample‐tilting configuration and the Theta Probe configuration. We determined photoelectron effective attenuation lengths (EALs) by two methods, one by analyzing photoelectron intensities as a function of film thickness for each emission angle (Method 1) and the other by analyzing photoelectron intensities as a function of emission angle for each film thickness (Method 2). Our analyses were made with simple expressions that had been derived with the assumption that elastic‐scattering effects were negligible. We found that EALs from both methods were systematically larger for the Theta Probe configuration, by amounts varying between 1% and 5%, than those for the sample‐tilting configuration. These differences were attributed to anisotropy effects in the photoionization cross section that are expected to occur in the former configuration. Generally, similar EALs were found by each method for each film material although larger EALs were found from Method 2 for film thicknesses less than 1.5 nm. SESSA is a useful tool for showing how elastic scattering of photoelectrons modifies EALs for particular materials, film thicknesses, and XPS configurations. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
84.
利用基于进化算法的晶体结构预测软件USPEX,并结合第一性原理方法对HfB的稳定晶体结构进行全局搜索。在基态条件下,新发现2个HfB晶体结构(空间群:P6m2和R3m)。其中,P6m2结构比已报道的HfB晶体结构(空间群:Pnma、Cmcm、I41/amd和Fm3m)具有更低的基态能量。这些结构中,B原子分别以二维类石墨烯(P6m2和R3m结构),zig-zag链(Pnma、Cmcm和41/amd结构)和孤立原子(Fm3m结构)3种形式存在,从而导致它们具有显著的化学键合特征、高温稳定性和强韧特性差异。 相似文献
85.
The chelating diamide lithium complex [Me2Si{NLiCH(Me)Ph}2]2 (1) was synthesized. The X‐ray structure of complex 1 reveals that in the solid state it is a dimer; every lithium atom is three coordinated. The [{Me2Si{NCH(CH3)Ph}2}ZrCl2LiCl(OEt2)2]2 (2) and [{Me2Si{NCH(CH3)Ph}2}HfCl2LiCl(OEt2)2]2 (3) complexes were formed by treatment of complex 1 with ZrCl4 and HfCl4 respectively in diethyl ether at ambient temperature. Complexes (2) and (3) were also characterized by X‐ray single‐crystal diffraction. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
86.
Synthesis and X-ray structural investigation of the hafnium(IV) complex with pivalyltrifluoroacetone
K. V. Zherikova N. B. Morozova E. V. Peresypkina I. A. Baidina I. K. Igumenov 《Journal of Structural Chemistry》2006,47(3):570-574
Synthesis and X-ray structural investigation of hafnium(IV) pivalyltrifluoroacetonate were carried out. Crystallographic data for C32H40F12HfO8 are: a = 19.913(3) Å, b = 11.8764(18) Å, c = 16.530(3) Å; β = 95.538(2)°; space group Cc, Z = 4, d calc = 1.637 g/cm3, R = 0.035. The structure is molecular; it is composed of discrete mononuclear Hf(ptac)4 molecules connected with each other by van der Waals interactions. The hafnium atom coordinates eight oxygen atoms belonging to four β-diketonate ligands; Hf-O distances are within the range 2.133–2.199 Å. 相似文献
87.
88.
We have made calculations of N 1s, O 1s, Si(oxide) 2p, Hf 4f, and Si(substrate) 2p photoelectron intensities at selected emission angles for films of SiO1.6N0.4 and HfO1.9N0.1 of various thicknesses on silicon. These calculations were made with the National Institute of Standards and Technology (NIST) Database for Simulation of Electron Spectra for Surface Analysis (SESSA) to investigate effects of elastic scattering and analyzer‐acceptance angle that could be relevant in the analysis of angle‐resolved X‐ray photoelectron spectroscopy (ARXPS) experiments. The simulations were made for an XPS configuration with a fixed angle between the X‐ray source (i.e. for the sample‐tilting mode of ARXPS) and with Al and Cu Kα X‐ray sources. The no‐loss intensities changed appreciably as elastic scattering was switched ‘on’ and ‘off’, but changing the analyzer‐acceptance angle had a smaller effect. Ratios of intensities for each line from the overlayer film for the least realistic model condition (elastic scattering switched ‘off’, small analyzer‐acceptance angle) to those from the most realistic model condition (elastic scattering switched ‘on’, finite analyzer‐acceptance angle) changed relatively slowly with emission angle, but the corresponding intensity ratio for the Si(substrate) 2p line changed appreciably with emission angle. The latter changes, in particular, indicate that neglect of elastic‐scattering effects can lead to erroneous results in the analysis of measured ARXPS data. The elastic‐scattering effects were larger in HfO1.9N0.1 than in SiO1.6N0.4 (due to the larger average atomic number in the former compound) and were larger with the Al Kα X‐ray source than with the Cu Kα source because of the larger cross sections for elastic scattering at the lower photoelectron energies. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
89.
Reactions of C(6)H(5)Li and 4-CH(3)C(6)H(4)Li with halides of Ti, Ir, Hf, and Nb lead to the formation of homoleptic organometallic anions of these metals. Owing to their thermal instability and their sensitivity towards H(2) O and O(2) , these compounds are characterized by single-crystal structure determinations at low temperature, whereas other physical data could only be obtained occasionally. Three pentacoordinate complex anions [Ti(C(6)H(5))(5)](-), [Ti(4-CH(3)C(6)H(4))(5)](-), and [Zr(C(6)H(5))(5)](-) have square-pyramidal structures that display only slight deviations from the ideal geometry, in contrast to the already known structures of [Ti(CH(5))(5)](-). The hexacoordinate complex anions [Zr(C(6)H(5))(6)](2-), [Zr(4-CH(3)C(6)H(4))(6)](2-), [Nb(C(6)H(5))(6)](2-), and [Nb(4-CH(3)C(6)H(4))(6)](2-) all have trigonal-prismatic structures, in accord with the known hexamethyl complex dianions. In contrast, the hexacoordinate complex anion [Hf(C(6)H(5))(6)](2)(-) has an octahedral or close to octahedral structure, in contrast to the known trigonal-prismatic structures of [Ta(C(6)H(5))(6)](-) and [Ta(4-CH(3)C(6)H(4))(6) (-). A qualitative explanation for this structural variability is given. 相似文献
90.