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991.
A computational study of the reactions of model II–VI precursors, MH2 (M=Zn, Cd, Hg) and H2E (E=O, S, Se, Te), is reported. The present computations yield several results of relevance to OMVPE of II–VI materials from MR2/ER precursors. Adduct formation is feasible at low temperatures, in line with recent experiments, but not at higher temperatures common in II–VI OMVPE. Calculations suggest that adducts are most likely to form after elimination has resulted in replacement of hydride with hydroxide ligands (in our model) or alkyl with alkoxide ligands (in larger models). The overall reaction MH2+2 H2E→M(EH)2 is generally more favorable, kinetically and thermodynamically, for lighter metals and heavier elements. On the basis of calculated thermodynamic and kinetic quantities, we conclude that the preferred pathway from reactants (MH2+2 H2E), except for M=Hg and E=Te, to an M(EH)2 intermediate is by way of a 1:2 adduct (or a similar portion of the potential energy surface in the absence of a bound adduct) followed by two successive H2 eliminations, in preference to the alternative in which adduct formation and H2 elimination occur in succession. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 71: 47–56, 1999 相似文献
992.
Weiwei Zhao Beibei Jin Longlu Wang Chengbo Ding Mengyue Jiang Tiantian Chen Shuaihang Bi Shujuan Liu Qiang Zhao 《中国化学快报》2022,33(1):557-561
One-dimensional ultrathin nanowires(NWs) offer a great deal of promising properties for electrochemical energy storage and conversion due to their nanoscale confinement effect and high surface-to-volume ratios. It is highly desirable to precisely design and synthesize ultrathin Ti3C2 NWs in the aspect of size,crystalline structure and composition. Here, we report a simple alkalization strategy to design the ultrathin Ti3C2 NWs for hydrogen evolution re... 相似文献
993.
A new structural type for melt cast materials was designed by linking nitrotetrazole ring with 1,2,4-oxadiazole through a N-CH2-C bridge for the first time. Three N-CH2-C linkage bridged energetic compounds, including 3-((5-nitro-2H-tetrazol-2-yl) methyl)-1,2,4-oxadiazole (NTOM), 3-((5-nitro-2H-tetrazol-2-yl)methyl)-5-(trifluoromethyl)-1,2,4 -oxadiazole (NTOF) and 3-((5-nitro-2H-tetrazol-2-yl)methyl)-5-amine-1,2,4-oxadiazole (NTOA), were designed and synthesized through a two-step reaction by using 2-(5-nitro-2H-tetrazole -2-yl)acetonitrile as the starting material. The synthesized compounds were fully characterized by NMR (1H, 13C), IR spectroscopy and elemental analysis. The single crystals of NTOM, NTOF and NTOA were successfully obtained and investigated by single-crystal X-ray diffraction. The thermal stabilities of these compounds were evaluated by DSC-TG measurements, and their apparent activation energies were calculated by Kissinger and Ozawa methods. The crystal densities of the three compounds were between 1.66 g/cm3 (NTOA) and 1.87 g/cm3 (NTOF). The impact and friction sensitivities were measured by standard BAM fall-hammer techniques, and their detonation performances were computed using the EXPLO 5 (v. 6.04) program. The detonation velocities of the three compounds are between 7271 m/s (NTOF) and 7909 m/s (NTOM). The impact sensitivities are >40 J, and the friction sensitivities are >360 N. NTOM, NTOF and NTOA are thermally stable, with decomposition points > 240 °C. The melting points of NTOM and NTOF are 82.6 °C and 71.7 °C, respectively. Hence, they possess potential to be used as melt cast materials with good thermal stabilities and better detonation performances than TNT. 相似文献
994.
Fu-Qiang Bi Yi-Fen Luo Jun-Lin Zhang Huan Huo Bo-Zhou Wang 《Molecules (Basel, Switzerland)》2021,26(23)
Rearrangement reactions are efficient strategies in organic synthesis and contribute enormously to the development of energetic materials. Here, we report on the preparation of a fused energetic structure of 7-nitro-3,5-dihydro-4H-pyrazolo[4,3-d][1,2,3]triazin-4-one (NPTO) based on a novel Hofmann-type rearrangement. The 1,2,3-triazine unit was introduced into the fused bicyclic skeleton from a pyrazole unit for the first time. The new compound of NPTO was fully characterized using multinuclear NMR and IR spectroscopy, elemental analysis as well as X-ray diffraction studies. The thermal behaviors and detonation properties of NPTO were investigated through a differential scanning calorimetry (DSC-TG) approach and EXPLO5 program-based calculations, respectively. The calculation results showed similar detonation performances between NPTO and the energetic materials of DNPP and ANPP, indicating that NPTO has a good application perspective in insensitive explosives and propellants. 相似文献
995.
996.
997.
Certain metal-catalyzed hydrosilations have been found to occur in a highly regioselective manner which makes them useful for the preparation of unique classes of ambifunctional monomers. These monomers bear two chemically different functional groups within the same molecule. By selection of the appropriate functional groups it is possible to design monomers in which the functional groups react independently, copolymerize, or polymerize by different mechanisms. This article describes some recent results of the synthesis and polymerization of several novel types of ambifunctional monomers. 相似文献
998.
999.
Qinglian Xu Faying Zheng Xiaotong Cao Ping Yang Yage Xing Ping Zhang Hong Liu Guangchao Zhou Xiaocui Liu Xiufang Bi 《Molecules (Basel, Switzerland)》2021,26(19)
Five different ultrafine milled flours (UMFs) were prepared from Tartary buckwheat via airflow ultrafine-grinding at different grinding pressures. The airflow ultrafine-grinding resulted in marked differences in particle size (from 100 to 10 μm). The UMFs were all brighter in appearance (higher L*) than Tartary buckwheat common flour (TBCF). Illustrated by the example of 70 °C, the UMFs were also found to have a greater water holding capacity (from 4.42 g/g to 5.24 g/g), water solubility (from 12.57% to 14.10%), and water solubility index (from 5.11% to 6.10%). Moreover, as the particle sizes reduced, the moisture content decreased (from 10.05 g/100 g DW to 7.66 g/100 g DW), as did the total starch content (from 68.88 g/100 g DW to 58.24 g/100 g DW) and the protein content (from 13.16% to 12.04%). However, the grinding process was also found to have negative effects on the mineral content of the Tartary buckwheat. Additionally, several substantial variations were found in their hydration properties along with grinding pressure changes in the differently ground UMFs. Consequently, fine Tartary buckwheat powders of a bright yellow color, with superior food processing properties, were prepared in this study by airflow ultrafine-grinding. 相似文献
1000.
用修正的Micka公式,从理论上描述了交流示波极谱图上切口的性质,用实验进行了验证。 相似文献