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51.
O. N. Babkina O. M. Chukanova E. E. Faingol"d N. M. Bravaya 《Russian Chemical Bulletin》2004,53(4):785-790
Quantitative characteristics of changes in the energy of charge transfer from -bonded ligands to metal are presented for the series of structurally similar ansa-metallocene complexes of IVB Group elements. The changes are caused by the solvation effect, replacement of -bonded chlorine ligands by methyl groups and of bridging ethylene groups by dimethylsilylene moieties, introduction of the methyl substituent into position 2 and phenyl substituent into position 4 of the indenyl system, variation of the transition metal in metallocene, and formation of complexes with polymethylalumoxane (MAO) at different AlMAO/Zr ratios. These effects are found to be additive. 相似文献
52.
用程序升温表面反应(TPSR)和程序升温还原(TPR)以及过渡应答(TR)等动态手段研究Ni/Al_2O_3催化剂表面上CO氢化反应的活性位状况。结果表明, 催化剂表面存在两种类型的活性位。其中A位来自表面上的聚晶体Ni, B位来自Ni与载体Al_2O_3强相互作用形成的Ni-Al化合物。实验结果还表明, CO在两个活性位都有吸附, 但在有H_2参与的条件下, 会影响二个活性位上的CO吸附量。 相似文献
53.
以Mossbauer谱为手段,研究了用于F-T合成的Fe/Zn催化剂的物相结构,并考察了组成及制备方法的影响,同时还对其还原、碳化行为进行了探讨.发现锌对铁的还原有抑制作用,它能够稳定二价铁不被进一步还原.研究还表明,我们所研制的Fe/Zn催化剂是一种高分散度的铁锌化合物,室温下具有超顺磁特性. 相似文献
54.
55.
A. V. Fionov M. V. Burova E. A. Tveritinova I. V. Krylova 《Russian Chemical Bulletin》2006,55(4):639-644
Donor-acceptor properties of alumina modified with lithium cations were studied by ESR of paramagnetic complexes of adsorbed
anthraquinone. The results were compared with the data on negative ion emission (exoemission) accompanying the decomposition
of isopropyl alcohol in the adsorption layer. The data on the activity measured by the pulse microcatalytic technique in isopropyl
alcohol decomposition are discussed. Small additives of lithium were found to promote catalytic activity of the samples. The
role of acid and basic sites in isopropyl alcohol decomposition was discussed.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 616–621, April, 2006. 相似文献
56.
57.
J?rg Libuda 《Chemphyschem》2004,5(5):625-631
Reaction kinetics on nanometer-scale particles are different from those on extended surfaces of bulk materials. This fact has been utilized for a long time to empirically maximize the performance of heterogeneous catalysts, but the understanding of the underlying effects is poor at the microscopic level. Modern molecular beam-based methods, however, allow us to derive very detailed kinetic information on catalytically active surfaces. In combination with structurally highly controlled model catalysts, microscopic insights into the activity and selectivity of specific reaction centers on catalyst nanoparticles can be obtained. This combined approach is illustrated through simple model reactions. 相似文献
58.
The addition of the macrocyclic polyether 18-Crown-6 (18C6) increases the selectivity of oxidation of ethylbenzene to -phenylethylhydroperoxide (PEH) in the presence of Ni(acac)2. The initial oxidation rate, selectivity and degree of conversion of ethylbenzene to PEH are greater than those catalyzed by Ni(acac)2 only. The efficiency of the macrocyclic ligand as an activator of Ni(acac)2 exceeds that of monodentate donor ligands. The high selectivity of the process is due to both the primary Ni(acac)2 · 18C6 complexes and the products of their transformation in the course of oxidation. The mechanism of ethylbenzene oxidation catalyzed by Ni(acac)2 · 18C6 complexes is discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1406–1411, August, 1994. 相似文献
59.
V. A. Pankratov Ts. M. Frenkel A. E. Shvorak S. V. Lindeman Yu. T. Struchkov 《Russian Chemical Bulletin》1993,42(1):81-87
A 11-complex of trinitrophenol with benzyldimethylamine (1) and a 111-complex, the product of the interaction of benzyldimethylamine, glycidyl phenyl ether, and phenol (2), have been synthesized and characterized by means of X-ray analysis. Complex1 is a precursor for the catalysts of selective isocyanate cyclotrimerization, while complex2 is one of those catalysts. In the crystal structure complex1 forms H-bonded cationic-anionic aggregates with proton transfer from phenol to the N-atom of the tertiary amine. Complex2 crystallizes as a monohydrate (2a) with a strong H-bond between the quaternary ammonium and phenolic components, and exists in crystals in the form of globular H-bonded dimeric hydrates. Possible pathways of dissociation of complex2a are discussed. The data obtained may be used as a basis for further interpretation of the regularities of cyclotrimerization of isocyanates catalyzed by complexes of this type.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No 1, pp. 92–97, January, 1993. 相似文献
60.
常压下以内循环无梯度反应器研究了B108铁基中温变换催化剂上水煤气变换反应宏观动力学。测定了反应速率,并用马夸特非线性参数估值法获得了幂函数宏观动力学模型r_s=37.67exp(-43982/RT)y_(CO)~(0.7552)y_(H_2O)~(-0.0367)Y_(CO_2)~(-0.4874)y_(H_2)(1-β)根据方差分析和残差分析,证实模型是高度显著的。由实验数据计算出相应反应条件下的效率因子。内扩散对原粒度B108催化剂上的反应具有严重影响。模型用于工业变换炉催化剂的用量核算,模型值与实际值符合良好。 相似文献