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81.
RExOy.nH2O对氟离子的吸附性能 总被引:3,自引:0,他引:3
La、Ce等稀土水含氧化物对阴离子的吸附性早有研究「‘-‘1,但从混合轻稀土氯化物制得的水合氧化物吸附F一的研究报道较少.为探讨难溶金属水合氧化物的除氟性能,本文以混合轻稀土氯化物为原料,制得其水含氧化物(RExOy·nH。O),采用高聚物造粒,研究了粒状RExOy·nH。O对F一的吸附性能及吸附机理.所用混合轻稀土氯化物由包头钢铁稀土公司提供,其主要组成(以氧化物计)为:CeO。(50%)、Nd。O3(25%)、La。O。(15%)、P36Oll(8%).聚丙烯睛分子量为(2.5~5)X10‘.其它试剂为分析纯.RExO.·nH。O参照文… 相似文献
82.
S. G. Wang Y.X. Qiu E. Neumann H. J. Deiseroth W. H. Eugen Schwarz 《无机化学与普通化学杂志》2003,629(10):1718-1730
About 60 molecular species composed of up to 10 mercury atoms and of oxygen atoms and/or of some other elements or groups (such as halogen, OH2, OH, H, alkali, NO3) have been investigated quantum chemically. Different density functional approaches and the ab initio SCF‐MP2 method were applied, comparing different basis sets and different atomic core sizes. It is important not to treat the Hg 5s, p, d as inactive core shells, and to use sufficiently many polarization functions. The shape of the 〉O‐Hg‐Hg‐O〈 units is not favorable concerning the formation of lattices composed of HgI, O and OH only. Despite its bulkiness, the OHgHgO units can easily come into contact with each other and then disproportionate. This is prevented in the so‐called ternary M‐HgI oxides by the embedded oxometallate (oxoacidic) anions. Furthermore, the HgI and HgII oxide bond energies are less favorable towards the stability of HgI oxo compounds, as compared to Hg halidic or oxoacidic compounds. Both points are not promising concerning the search for HgI oxides/hydroxides, although the preparation of such compounds, including spacer groups, by topochemical reactions can still not be excluded. So far, experimental efforts towards the synthesis of such a new class of compounds have only demonstrated that HgII is strictly preferred over HgI in the formation of solids of binary Hg‐O or ternary A‐Hg‐O composition (A = electropositive metal such as alkali, in contrast to M = transition or semi‐metal). This is so even if compounds containing ‘electron rich Hgδ— atoms’ (i.e. A‐Hg amalgams) are oxidized under mild conditions. 相似文献
83.
The reaction of M2(O2CBu(t))4 (M = Mo, W) with a dicarboxylic acid in toluene yields compounds of general formula [M2]-O2C-X-CO2-[M2] ([M2] = M2(O2CBu(t))3; X = conjugated spacer). The M2 units are electronically coupled via interactions between the M2 delta and dicarboxylate pi* orbitals, and the magnitude of this coupling is revealed by electronic structure calculations and spectroscopic data. These compounds show intense metal to ligand charge transfer (MLCT) absorptions in the visible region of the electronic spectrum that are temperature and solvent dependent. Evidence of electronic coupling is seen in their cyclic voltammograms, which show two successive one-electron oxidations. The extent of electronic coupling in the mixed valence radical cations [M2]-O2C-X-CO2-[M2]+, generated by oxidation with one equivalent of AgPF6 or FeCp2PF6, is evaluated by EPR and UV-vis-NIR spectroscopic data, and delocalized behavior is observed in compounds with W2 units separated by up to 13.6 angstroms. The simplicity of the frontier M2 orbital interactions with the bridge pi orbitals provides a convenient system with which to study electron transfer in mixed valence systems, as compared to the extensively studied, but more complicated, dinuclear t(2g)6/t(2g)5 mixed valence compounds. Oligomeric and polymeric compounds incorporating M2 units have also been synthesized, having general formula [M2(O2CR)2(O2C-Thio-CO2)]n (Thio = n-hexyl substituted ter- and quinque-thiophenes). They can be deposited as thin films by spin coating, and show photoluminescence and electroluminescence. These metallo-polythiophenes show potential for application in electronic materials. ( 相似文献
84.
The texture of Cr2O3-K2O/Al2O3catalysts containing oxides of rare earth elements (REE) was studied. The catalysts are used for the synthesis of 2-methylthiophene by the reaction of H2S with n-pentane or piperilene. The heterocyclization of n-pentane is a consecutive reaction involving a step of dehydrogenation of initial hydrocarbon. At this step the texture of the catalyst affects the yield of 2-methylthiophene. The yield of 2-methylthiophene obtained from piperilene and I2S is independent of the catalyst texture. 相似文献
85.
Preparation of Mn3O4 nanocrystallites by low-temperature solvothermal treatment of γ-MnOOH nanowires
The preparation of trimanganese tetroxide (Mn3O4) nanocrystallites from γ-MnOOH nanowires under mild conditions has been achieved by two steps: first, γ-MnOOH nanowires with a mean diameter of about 12 nm and lengths of up to several micrometers were directly prepared via hydrothermal reaction between KMnO4 and toluene in water at 180°C for 24 h; then, pure Mn3O4 nanocrystallites could be obtained by solvothermal treatment of the γ-MnOOH nanowires in ethylenediamine (EDA) and ethylene glycol (EG) at 150°C for 24 h. It was found that the Mn3O4 product obtained in EDA comprised well-defined nanocrystallites with the size in the range of 15-35 nm, while the one obtained in EG consisted of aggregated nanoparticles with the size of less than 18 nm.The possible formation mechanism of nanocrystalline Mn3O4 in EDA and EG and reasons for the different effects of various solvents on the products were also proposed. 相似文献
86.
Pt/钇稳定氧化锆固体电解质在高温下的电化学性质 总被引:1,自引:0,他引:1
用交流阻抗技术研究了二电极、三电极Pt/钇稳定氧化锆(简称YSZ)高温固体电化学体系.开路电位下,Pt/YSZ体系只有一个阻抗半圆,对应于电极体系的电化学活化控制过程,极化电阻随温度变化的表观活化能为171.5kJ/mol.Pt/YSZ界面的双电层电容约为300μF/cm2.阳极极化下,交流阻抗极化电阻显著减小;阴极极化下,极化电阻反而增大,并出现浓差控制现象. 相似文献
87.
New process to control hydrolysis step during sol-gel preparation of sulfated zirconia catalysts 总被引:2,自引:0,他引:2
Sulfated zirconia catalysts were prepared by sol-gel process using a new method allowing the control of the hydrolysis step
of zirconium alkoxides. Prepared samples were characterized by N2 adsorption (desorption) at 77 K, XRD, chemical analysis of total sulfur and XPS. Catalytic properties have been evaluated
in n-butane and n-hexane isomerization reactions. Obtained results show that time necessary for gelation is significant and
depends considerably on the nature of the zirconium precursor. Concerning the properties of the solids obtained by this method,
it has been noted that the use of the zirconium propoxide led to a better retention of the sulfate species, which improves
activity during isomerization reactions. It has been found also that an initial S/Zr molar ratio equal to 0.5 allowed to obtain
an optimal sulfur content and a high specific surface area. 相似文献
88.
Synthesis, structure and magnetic properties of the S=1/2, one-dimensional antiferromagnet, Y5Re2O12
Lisheng Chi 《Journal of solid state chemistry》2003,172(2):451-457
Single crystals of Y5Re2O12 have been grown, and the crystal structure has been determined by X-ray diffraction. This compound crystallizes in space group C2/m with cell dimensions of a=12.4081(10) Å b=5.6604(5)Å, c=7.4951(6) Å, β=107.837(3)°, Z=2. The final refinement led to R1=0.0238, WR2=0.0459 for 1053 observed reflections with F>4σ(F0). Edge-sharing ReO6 octahedra form infinite linear [ReO2O4/2]n chains along the b direction with alternating short and long Re-Re distances. Three crystallographically independent yttrium atoms surround O2 to form OY4 tetrahedra, which share edges and corners in the ab plane to form a two-dimensional Y5O4 network which separates the [ReO2O4/2]n magnetic chains. This compound is therefore isostructural with the series Ln5Re2O12Ln=Gd-Lu, which have been known since 1969. The average Re oxidation state is +4.5 in the chains and a reasonable, if qualitative MO scheme results in one unpaired electron per Re dimer. Consistent with this, magnetic susceptibility data can be fitted to the one-dimensional antiferromagnetic Heisenberg model with S=1/2 and parameters Jintra/k=−89(1)K, g=2.15(4) and χ(TIP)=5(1)×10−4 emu/mol. There is no sign of long-range magnetic order down to 2 K. These results are contrasted with those for the isostructural Y5Mo2O12. 相似文献
89.
高效石墨浮选剂的合成金婵,薛玉,汪进,刘欣荣,秦英海(哈尔滨工业大学应用化学系哈尔滨150001)(大庆石化总公司大庆)关键词石墨,浮选剂,合成,混合烃由于石墨具有良好的力学性能、导电、高熔点等性质,广泛用于原子能、宇航和民用工业。隐晶质石墨属于微晶... 相似文献
90.
溶胶-凝胶法制备还原态K-Co-Mo催化剂的合成醇性能 总被引:2,自引:1,他引:2
应用溶胶-凝胶法制备了还原态K-Co-Mo催化剂, 比较了不同的组分和不同的反应条件对合成醇性能的影响。实验结果表明,适量钾和钴助剂的添加能显著提高催化剂合成醇的性能,尤其是提高了C2+醇的选择性。此外,反应温度、压力以及空速对合成醇影响明显,升高温度可以提高催化反应中低碳醇的收率,但选择性下降;增加压力和空速可以提高低碳醇的收率和选择性,对合成低碳醇有利。在230 ℃,6.0 MPa,14 400 h-1条件下,催化剂合成低碳醇的收率为375.4 g/kg·h,选择性为70.2%,C1OH/C2+OH为0.48。 相似文献