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排序方式: 共有325条查询结果,搜索用时 15 毫秒
1.
A series of 3-perfluoroalkylbenzoate esters are synthesised. They tend to exhibit enantiotropic SmA and SmC phases. The clearing points are decreased with increasing the alkoxy chain length and show odd-even effect. With increasing the fluorocarbon chain length, the melting and clearing points increase; however, the SmC phase is suppressed. 相似文献
2.
Zhaoheng Li Qijun Yu Xiaowen Chen Hao Liu Jiyao Zhang Junlu Zhang Yongmin Yang Jiangxiong Wei 《Journal of Thermal Analysis and Calorimetry》2017,127(3):1897-1909
The compounds of MgO–silica fume (SF) pastes constitute magnesium silicate hydrate (M–S–H) in a new generation of basic castables. However, Mg(OH)2 is a common reaction product with the formation of M–S–H. This study aims to reduce the formation of Mg(OH)2 in MgO–SF pastes. In this study, MgO powders were prepared by calcining magnesite at different temperatures and then mixed with SF and water to prepare MgO–SF pastes. The properties of MgO powders were characterized, and the pH values in the pore solutions of MgO–SF pastes were measured. The MgO–SF pastes cured for 90 days were calcined at 500, 700, 900 and 1200 °C, and the microstructure was characterized afterward. The results showed that both the reactivity of MgO powders and the pH value of the pore solution of MgO–SF pastes were diverse, which essentially depended on the grain sizes and the crystalline degree of MgO. Increasing the calcination temperature of MgO was beneficial to reduce the formation of Mg(OH)2 or even stop it when using MgO calcined at 1450 °C. Enstatite and forsterite formed for all MgO–SF pastes after calcination. However, the microstructure of MgO–SF paste with MgO calcined at 1450 °C was denser than others. MgO–SF pastes were suitable for the new-generation refractory castables. Notably, using MgO calcined at 1450 °C is more appropriate. 相似文献
3.
The pinacolic coupling of aromatic aldehydes and ketones was performed with samarium/mercury amalgam in THF at room temperature to afford the corresponding 1,2-diols in good yields. 相似文献
4.
Organosamarium reagent reacts with disulfides to afford allyl sulfides in THF. 相似文献
5.
Promoted by metallic cadmium which was produced by reduction of CdCl2 H2O with samarium in situ, allyl bromide and α-bromocarboxylates react with diorgano diselenides in aqueous solutions to give allylic-type selenides and α-selenocarboxylates in moderate to good yields. 相似文献
6.
Nitroarenes can be reduced to the corresponding primary amines in good yields with Cp2TiCl2/Sm system under mild and neutral conditions. 相似文献
7.
Zinc-mediated reductive dimerization cyclization of 1,1-dicyanoalkenes 1 occurs to give functionalized cyclopentenes 2(cis) and 3(trans) in good yields under saturated aqueous NH4Cl-THF solution at room temperature. 3 is major product. 相似文献
8.
Anode-supported tubular solid oxide fuel cells (SOFCs) with Cu–CeO2–yttria-stabilized zirconia (YSZ) anode, YSZ electrolyte film, and silver cathode were fabricated. The cells were tested with 5 wt% Fe-loaded activated carbon and dry CO, respectively, and their performances were compared to verify the reaction mechanism of direct carbon SOFCs (DC-SOFCs). The corresponding current–voltage curves and impedance characteristics of the cells operating on these two different fuels were found to be almost the same at high temperatures, demonstrating the presumed mechanism that the anode reaction of a DC-SOFC is the electrochemical oxidation of CO, just as in a SOFC operated directly on CO. Some experimental evidences including the difference in open circuit voltage at different temperatures and the operating stability of the cells were analyzed in detail. 相似文献
9.
10.
β-Ketosulfones can be readily desulfonylated with TiCl4/Sm system to give corresponding ketones in acceptable yields in THF under mild conditons. 相似文献