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131.
The 17-electron species [M(CO)5χLχ] (M Mn, Re, χ 0; M Mn, Re; L Ph3P, χ 1, 2; M Mn, Re; L (o-MeC6H4O)3P, χ 2; M Mn; L (p-ClC6H4O)3P, (PhO)3P, χ 2; M Mn; L P(OMe)3, χ 3) have been generated by one electron oxidation of the corresponding anions and show typical radical reactivity, undergoing dimerisation or hydride abstraction in reactions controlled by steric effects. Evidence is presented for the source of the hydrogen atom. The 19-electron species [M(CO)3(η7-C7H7)]? (M Cr, Mo) and [Fe(CO)3(η5-C6H7)]?, generated by reduction of the corresponding cations, undergo dimerisation at the organic ligand. Similar treatment of [Fe(CO)2-L(η-cp)]+ (L CO, PPh3, P(OPh)3, Me2CO) yields [Fe2(CO)4(η-cp)2] and these reduction reactions are rationalised in terms of the nature of the HOMO in the intermediate radical. Similar reduction of [Rh(diphos)2]+ yield the 17-electron intermediate [Rh(diphos)2] and this also undergoes hydrogen abstraction. 相似文献
132.
W. Pyckhout P. Van Nuffel C. Van Alsenoy L. Van Den Enden H. J. Geise 《Journal of Molecular Structure》1983,102(3-4):333-345
The gas phase molecular structure of methyl vinyl ether at room temperature has been studied by joint analysis of electron diffraction and microwave data. Constraints on geometrical and thermal parameters were derived from the geometry and force field of the s-cis form, obtained by ab-initio calculations (4–21 G basis set) after complete geometry relaxation. A range of models was investigated that fits all available data (infrared, microwave and electron diffraction). The following rg/r-parameters were obtained: C=C: 1.337 Å, C(sp2)---O: 1.359 Å, C(sp3)---O: 1.427 Å, : 1.102 Å C=C---O : 127.3° and COC: 116.8°. Experimental rg---re (ab initio) corrections are given for C=C, C(sp2)---O and Csp3)---O.
This investigation demonstrates that molecular orbital constrained electron diffraction is sufficiently reliable and in such a manner that it can be applied to more complicated problems. 相似文献
133.
Study on oxidation of polymers treated by high LET radiation 总被引:2,自引:0,他引:2
Wang Ruiyu Ha Hongfei Wang Yugang Zhao Weijiang Yan Sha Jin Changwen Wang Guanghui Wu Jilan 《Radiation Physics and Chemistry》1998,52(1-6):251-256
The oxidation of medical silicone rubber and segmented polyether urethane which were bombarded with 11.2 MeV Si+ or F+ at the dose of 5 × 1014 ions/cm2 was studied. In XPS measurements, it was found that the oxygen concentration on the surface of the implanted polymeric membranes had been increasing in three months at least. ESR measurement showed that some free radicals existed in these membranes and their quantities decreased with time. Chemical analysis proved that peroxides were generated in the γ irradiated membranes. The reason for the increasing of oxygen concentration was that free radicals combined with oxygen in the air and produced peroxides on the membrane surface. Moreover, in order to demonstrate the radiation mechanism, low LET (γ rays) radiation of such polymeric membranes was carried out for comparison 相似文献
134.
trans-PtH2[As(t-Bu)3]2 was prepared in very good yield by afacile reaction of K2PtC14 with As(t-Bu)3 in alkaline ethanol. Treatment of trans-PtH2[As(t-Bu)3]2 with CF3CO2H or HCI afforded trans-PtH(O2CCF3)[As(t-Bu)3]2 or trans-PtHCl[As(t-Bu)3]2. respectively, in almost quantitative yield. 相似文献
135.
The coalescence temperature for the C-methyl peaks in the NMR spectra of hydrazones of acetone are above 200°, indicating an energy barrier for syn-anti isomerization greater than 28 kcal mole?1. the presence of halogenated compounds decreases the energy barrier, due to the formation of a charge transfer complex between the hydrazone acting as a donor and the halogenated compound acting as the electron acceptor. 相似文献
136.
Treatment of transition-metal—ammonia complexes with ketones yields complexes with RR′CNH ligands. Of particular interest is the stabilization of dialkylketimines such as e.g. (CH3)2CNH and C6H10NH in [M(CO)5{NHC(CH3)2}] or [M(CO)5 {NHC6H10}] (M = Cr, Mo, W). The principle of synthesis may be applied to a wide range of different metals and types of complexes, as can be shown by the synthesis of [C5H5Mn(CO)2 {NHC(CH3)2}], [C5H5Fe(CO)2{NHC(CH3)2}]PF6, [M(CO)4L2] (M = Cr, Mo, W; L = (CH3)2CNH, C6H10NH) and [W(CO)3(diphos){NHC(CH3)}2]. Treatment of [Cr(CO)5NH3] with urotropine gives [Cr(CO)5 {N4(CH2)6}] which is also obtained from [Cr(CO)5THF] and urotropine. The methods of preparation, reactions and spectroscopic properties of the complexes are reported. 相似文献
137.
The reaction of tert-butylamine, isoxazolidine and hydrazine with N-[(3-chloropropyl)oxy]phthalimide is investigated. A convenient synthesis of oxazolidine is described. 相似文献
138.
The phase diagram for the binary system K2CrO4CaCrO4 has been determined for CaCrO4 concentrations up to 60 mole%, using the techniques of differential thermal analysis, X-ray diffraction, and drop calorimetry. Essential features of the phase diagram are: the solid-solid phase transition for pure K2CrO4 at 670°C, β-K2CrO4 ? α-K2CrO4; a eutectoid reaction at 14 mole% CaCrO4 and 548°C, β-K2CrO4 ? α-K2CrO4 + K2CrO4 · CaCrO4; a peritectoid event at 50 mole% CaCrO4 and 640°C, β-K2CrO4 + CaCrO4 ? K2CrO4 · CaCrO4; and a eutectic reaction at 51 mole% CaCrO4 and 678°C, L ? β-K2CrO4 + CaCrO4. X-ray diffraction studies lead to the determination of the unit cell dimensions for the K2CrO4 · CaCrO4 double salt, a C-centered monoclinic form with a0 = 7.615(6) Å, b0 = 22.797(15) Å, c0 = 9.777(9) Å, β = 115.45(5)°. 相似文献
139.
K. Yabuta N. Kinomura M. Shimada F. Kanamaru M. Koizumi 《Journal of solid state chemistry》1980,33(2):253-256
The complete solid solutions of Cr1?xFexOOH with the InOOH-type structure were synthesized under high pressures. They were antiferromagnetic with Néel temperatures of 570 K for FeOOH, 454 K for Cr0.2Fe0.8OOH, 332 K for Cr0.4Fe0.6OOH, and 160 K for Cr0.6Fe0.4OOH as determined by the Mössbauer effect measurements. 相似文献
140.
Samples of head-to-head polypropylene have been prepared by the hydrogenation of two polydienes; 1,4-poly(2,4-hexadiene) and 1,4-poly(2,3-dimethyl-1,3-butadiene). Glass transition temperatures were found to be marginally lower than for conventional polypropylene suggesting that the head-to-head placements in the chain increased the polymer flexibility. 相似文献