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961.
四苯基卟啉金属螯合物的反相高效液相色谱保留行为研究 总被引:13,自引:0,他引:13
研究了四苯基卟啉金属螯合物(TPP)的高效液相色谱保留行为。在C18柱上试验以各种有机溶剂洗脱金属螯合物,最终选择了甲醇-丙酮的非 水体系作流动相。各螯合物的保留顺序为:ZnTPP<TPP<NiTPP<CuTPP。运用Horvath的疏溶剂理论解释了这种保留行为。文中采用电负性与离子半径之比(EN/ri)作为静电场强的量度,提出 EN/ri值作为四苯基卟啉金属螯合物保留值参数。实验发现,在不同的流动相配比条件下,lnk′与 EN/ri均呈良好的线性关系。 相似文献
962.
963.
Gaur B. Lochab B. Choudhary V. Varma I. K. 《Journal of Thermal Analysis and Calorimetry》2003,71(2):467-479
The paper describes the synthesis of low molecular mass poly(allyl chloride) (PAC) (M
n= 856-3834 g mol-1) using Lewis acid (ALCL3, FeCL3, TiCL4) and al powder. Branching in PAC was indicated on the basis of elemental analysis and 1H-NMR spectroscopy. azidation of pac could be carried out at 100°C by using NaN3 and DMSO as solvent. Curing of poly(allyl azide) (PAA) by cyclic dipolar addition reaction with EGDMA (ethylene glycol dimethacrylate,
5-45 phr) was investigated by differential scanning calorimetry and structure of cured polymer was confirmed by FTIR. A two-step
mass loss was exhibited by uncured and cured PAA in nitrogen atmosphere. A mass loss of 20-28% (155-274°C) and 50-61% (330-550°C)
was observed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
964.
Guan-Yeow Yeap Tiang-Chuan Hng Sue-Yi Yeap Ewa Gorecka Masato M. Ito Koichi Ueno 《Liquid crystals》2013,40(12):1431-1441
Ten new non-symmetric liquid crystal dimers belonging to the family of compounds α-(4-benzylidene-substituted-aniline-4′-oxy)-ω-(2-methylbutyl-4′-(4″-phenyl)benzoateoxy)-alkanes have been synthesised and their transitional properties characterised. The dimers contain either a hexamethylene or octamethylene spacer, while the terminal substituents on the 4-benzylideneaniline fragment are H, CH3, F, Cl and Br. The unsubstituted dimers are not liquid crystalline, while the remaining compounds exhibit enantiotropic nematic behaviour. The trends in the clearing temperatures, according to the chemical nature of the terminal substituent, are largely consistent with those established for conventional low molar mass liquid crystals. Three of the dimers also exhibit an intercalated smectic A phase, specifically the two bromo-substituted dimers and the chloro-substituted dimer containing a hexamethylene spacer. The driving force for the formation of this phase is considered to be, at least in part, the specific anisotropic interaction between the unlike mesogenic units. The absence of smectic behaviour for the isosteric methyl-substituted dimers reveals that steric factors alone cannot stabilise the intercalated smectic A phase. 相似文献
965.
The new zinc ternary complexes [Zn(cyclen)NO3]ClO4 (I), [Zn2(cyclen)2(m-nic)](ClO4)3 (II), [Zn2(cyclen)2(m-pic)](ClO4)3 (III) (cyclen=1,4,7,10-tetraazacyclododecane; nic=nicotinic acid; pic=picolinic acid) were synthesized and their spectral and thermal properties were investigated. The compounds were characterized
by elemental analysis, IR spectroscopy and TG/DTG, DTA methods. Moreover, the way of coordination of pyridinecarboxylate anions
was proposed on the basis of the spectral data and consequently proved with results of X-ray structure analysis.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
966.
967.
Davide Collini Serena Fedi Cristina Femoni Francesco Kaswalder Maria Carmela Iapalucci Giuliano Longoni Piero Zanello 《Journal of Cluster Science》2005,16(3):455-476
The reaction of the [Ni6(CO)12]2− dianion with [Rh(COD)Cl]2 (COD = cyclooctadiene) in acetone affords a mixture of bimetallic Ni–Rh clusters, mainly consisting of the new [Ni7Rh3(CO)18]3− and [Ni8Rh(CO)18]3− trianions. A study of the reactivity of [Ni7Rh3(CO)18]3− led to isolation of the new [Ni3Rh3(CO)13]3− and [NiRh8(CO)19]2− anions. All these new bimetallic Ni–Rh carbonyl clusters have been isolated in the solid state as tetrasubstituted ammonium
salts and have been characterised by elemental analysis, X-ray diffraction studies, ESI-MS and electrochemistry. The unit
cell of the [NEt4]3[Ni7Rh3(CO)18] salt contains two orientationally-disordered ν2-tetrahedral [Ni7Rh3(CO)18]3− trianions with occupancy factors of 0.75 and 0.25. Besides, their inner Ni3Rh3 octahedral moieties show two cis sites purely occupied by Rh atoms, two trans sites purely occupied by Ni atoms and the remaining two cis sites are disordered Ni and Rh sites with respective occupancy fraction of 0.5. At difference from the parent [Ni7Rh3(CO)18]3−, the octahedral [Ni3Rh3(CO)13]3− displays an ordered distribution of Ni and Rh atoms in two staggered triangles. The [NiRh8(CO)19]2− dianion adopts an isomeric metal frame with respect to that of the [PtRh8(CO)19]2− congener. As a fallout of this work, new high-yield synthesis of the known [Ni6Rh3(CO)17]3− and [Ni6Rh5(CO)21]3−, as well as other currently-investigated bimetallic Ni–Rh clusters have been obtained. 相似文献
968.
[Na(12-Crown-4)2]2[Ni(Se4)2] · DMF; Synthesis, Crystal Structure, and Magnetic Behaviour The title compound has been prepared from NiCl2 and sodium polyselenide in dimethylformamide solution in the presence of 12-crown-4, forming black crystal needles. They were characterized by an X-ray structure determination, by FIR spectroscopy as well as by the magnetic behaviour. [Na(12-crown-4)2]2[Ni(Se4)2] · DMF crystallizes monoclinically in the space group P21, 3650 observed unique reflections, R = 0.046. Lattice dimensions at ?80°C: a = 1020.3(2); b = 1889.5(2); c = 1498.7(3) pm; β = 108.29(1)°. The compound has an ionic structure, in which the sodium atoms of the [Na(12-crown-4)2]+ cations are coordinated by the oxygen atoms of the crown ether molecules in an antiprismatic fashion. The nickel atom of the anion [Ni(Se4)2]2? is surrounded by four selenium atoms of the tetraselenide chelates in an almost planar environment. The DMF molecules are inserted in the lattice without a bonding interaction. The magnetic susceptibility observed in the temperature interval 4.2 to 330K can be interpreted by means of a 3E ground term and D2 as local symmetry, which was established by X-ray crystallography. 相似文献
969.
单壁碳纳米管的力学行为是纳米复合材料和纳米器械的基本问题之一.使用有限元方法系统地研究了单壁碳纳米管的轴压和纯弯变形,并将有限元模拟结果和分子动力学模拟结果进行了比较.研究结果表明单壁碳纳米管的轴压屈曲载荷受直径变化的影响;单壁碳纳米管在弯曲载荷作用下的屈曲和后屈曲行为强烈地依赖于管长和管径的变化,合理地选择碳纳米管的弹性模量和壁厚,有限元方法能够很好地解释碳纳米管的屈曲机理.研究大尺度的纳米力学问题时,有限元方法将会成为更加准确、快捷的数值模拟方法.
关键词:
单壁碳纳米管
非线性力学行为
有限元 相似文献
970.
《Acta Crystallographica. Section C, Structural Chemistry》2017,73(2):91-96
Subtle modifications of N‐donor ligands can result in complexes with very different compositions and architectures. In the complex catena‐poly[[bis{1‐[(1H‐benzotriazol‐1‐yl)methyl]‐1H‐imidazole‐κN 3}copper(II)]‐μ‐benzene‐1,3‐dicarboxylato‐κ3O 1,O 1′:O 3], {[Cu(C8H4O4)(C10H9N5)2(H2O)]·2H2O}n , each CuII ion is six‐coordinated by two N atoms from two crystallographically independent 1‐[(1H‐benzotriazol‐1‐yl)methyl]‐1H‐imidazole (bmi) ligands, by three O atoms from two symmetry‐related benzene‐1,3‐dicarboxylate (bdic2−) ligands and by one water molecule, leading to a distorted CuN2O4 octahedral coordination environment. The CuII ions are connected by bridging bdic2− anions to generate a one‐dimensional chain. The bmi ligands coordinate to the CuII ions in monodentate modes and are pendant on opposite sides of the main chain. In the crystal, the chains are linked by O—H…O and O—H…N hydrogen bonds, as well as by π–π interactions, into a three‐dimensional network. A thermogravimetric analysis was carried out and the fluorescence behaviour of the complex was also investigated. 相似文献