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91.
92.
Ryohei Oka Jun-ichi Koyama Takuro Morimoto Toshiyuki Masui 《Molecules (Basel, Switzerland)》2021,26(20)
La3LiMn1−xTixO7 (0 ≤ x ≤ 0.05) samples were synthesized by a solid-state reaction method, and a single-phase form was observed for the samples in the range of x ≤ 0.03. Crystal structure, optical properties, and color of the La3LiMn1−xTixO7 (0 ≤ x ≤ 0.03) samples were characterized. Strong optical absorption was observed at a wavelength between 400 and 550 nm, and a shoulder absorption peak also appeared around 690 nm in all samples; orange colors were also exhibited. Among the samples synthesized, the most brilliant orange color was obtained at La3LiMn0.97Ti0.03O7. The redness (a*) and yellowness (b*) values of this pigment were higher than those of the commercially available orange pigments. Therefore, the orange color of this pigment is brighter than those of the commercial products. Since the La3LiMn0.97Ti0.03O pigment is composed of non-toxic elements, it could be a new environmentally friendly inorganic orange pigment. 相似文献
93.
Diradical Character Tuning for the Third‐Order Nonlinear Optical Properties of Quinoidal Oligothiophenes by Introducing Thiophene‐S,S‐dioxide Rings 下载免费PDF全文
Dr. Ryohei Kishi Shoki Ochi Shioh Izumi Akihiro Makino Takanori Nagami Jun‐ya Fujiyoshi Naoyuki Matsushita Michika Saito Prof. Dr. Masayoshi Nakano 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(4):1493-1500
To create a design guideline for efficient third‐order nonlinear optical (NLO) molecules, the chain‐length (n) dependences of the diradical character y and the longitudinal second hyperpolarizability γ of quinoidal oligothiophenes (QTs), from monomers to octamers, involving thiophene‐S,S‐dioxide rings are investigated by using the density functional theory method. It turns out that the diradical character of the modified QTs is reduced as compared to those of the pristine QTs. By introducing an appropriate number of oxidized rings into the QT framework, intermediate y values can be achieved even in the systems with large values of n, in which the pristine QTs are predicted to have pure diradical character. Such intermediate diradical oligomers are shown to exhibit enhanced γ values as compared to the pristine QTs with the same value for n. From the calculation results, the introduction of the optimal number of thiophene‐S,S‐dioxide rings is predicted to be an efficient chemical modification for optimizing the third‐order NLO properties of open‐shell QTs through tuning the diradical characters. 相似文献
94.
95.
[reaction: see text] A new iridium-catalyzed oxidative cyclization of amino alcohols has been revealed. Indole derivatives are synthesized in good to excellent yields from 2-aminophenethyl alcohols by means of a [CpIrCl(2)](2)/K(2)CO(3) catalytic system. The present catalytic system is also effective for syntheses of 1,2,3,4-tetrahydroquinolines from 3-(2-aminophenyl)propanols and 2,3,4,5-tetrahydro-1-benzazepine from 4-(2-aminophenyl)butanol. 相似文献
96.
Suguru Ohta Masayoshi Nakano Takashi Kubo Kenji Kamada Koji Ohta Ryohei Kishi Nozomi Nakagawa Benoît Champagne Edith Botek Shin-ya Umezaki Akihito Takebe Hideaki Takahashi Shin-ichi Furukawa Yasushi Morita Kazuhiro Nakasuji Kizashi Yamaguchi 《Chemical physics letters》2006,420(4-6):432-437
The static second hyperpolarizability (γ) of a singlet diradical system involving phenalenyl radicals linked with acetylene π-conjugated bridge, BPLE, is investigated as well as reference closed-shell systems, BPRY1 and BPRY2, by the hybrid density functional theory method. The γ value of BPLE with intermediate diradical character is shown to be about four times as large as that of BPRY1 with similar π-conjugation length and to be about twice as large as that of BPRY2 with longer π-conjugation length. This feature is in agreement with our prediction that the molecules with intermediate diradical characters enhance γ values compared to the closed-shell molecules. 相似文献
97.
Watanabe T Tanaka Y Shoda R Sakamoto R Kamikawa K Uemura M 《The Journal of organic chemistry》2004,69(12):4152-4158
Naphthyl tetrahydroisoquinoline alkaloids, atropisomeric korupensamines A and B and ent-korupensamine B, were synthesized by syn-selective cross-coupling of a planar chiral arene chromium complex with naphthylboronic acid and subsequent axial isomerization or tricarbonylchromium migration to the inverted arene face as a key step. Palladium(0)-catalyzed cross-coupling of planar chiral arene chromium complex 12 with naphthylboronic acid 9 gave syn-biaryl coupling product 13. syn-Biaryl chromium complex 13 was heated in 1:1 mixture of di-n-butyl ether and 1,2-dichloroethane to give a face-inverted anti-biaryl chromium complex 14 without axial isomerization. Korupensamine A was synthesized from the syn-biaryl chromium complex 13 via o-formyl syn-biaryl chromium complex 10, and ent-korupensamine B was prepared from the face-inverted anti-biaryl chromium complex 14. On the other hand, difluoro-substituted syn-biaryl chromium complex 40 with a formyl group afforded anti-biaryl chromium complex 41 containing a rotated central bond by heating in xylene. The chromium-complexed fluorine atom was easily substituted with an isopropoxy group by nucleophilic substitution. Use of these reactions allowed (+)-2-bromo-3,5-difluorobenzaldehyde chromium complex (37) as a single chiral source to be converted to atropisomeric korupensamines A and B, respectively. 相似文献
98.
Reductive Cross‐Coupling of Conjugated Arylalkenes and Aryl Bromides with Hydrosilanes by Cooperative Palladium/Copper Catalysis 下载免费PDF全文
Dr. Kazuhiko Semba Kenta Ariyama Dr. Hong Zheng Ryohei Kameyama Prof. Dr. Shigeyoshi Sakaki Prof. Dr. Yoshiaki Nakao 《Angewandte Chemie (International ed. in English)》2016,55(21):6275-6279
A method for the reductive cross‐coupling of conjugated arylalkenes and aryl bromides with hydrosilanes by cooperative palladium/copper catalysis was developed, thus resulting in the highly regioselective formation of various 1,1‐diarylalkanes, including a biologically active molecule. Under the applied reaction conditions, high levels of functional‐group tolerance were observed, and the reductive cross‐coupling of internal alkynes with aryl bromides afforded trisubstituted alkenes. 相似文献
99.
Dr. Haiwang Lai Changming Jin Dr. Junsu Park Dr. Ryohei Ikura Prof. Yoshinori Takashima Prof. Makoto Ouchi 《Angewandte Chemie (International ed. in English)》2023,62(14):e202218597
In this study, we designed a methacrylate molecule with an alkyl-substituted trichloro salicylic acid pendant as a transformable bulky monomer to enable the synthesis of an alternating copolymer of methyl methacrylate (MMA) and n-butyl acrylate (nBA). The adamantyl-substituted methacrylate monomer ( 1-Ad ) showed very low homopolymerization propensity in radical polymerizations, but afforded the alternating copolymer with nBA via copolymerization. The 1-Ad units in the resultant copolymer were quantitatively and selectively transformed into MMA via transesterification with methanol to yield the alternating copolymer of MMA and nBA. Its alternating sequence was clearly demonstrated by a structural analysis via 13C NMR spectroscopy as well as the low reactivity ratios for the 1-Ad and nBA pair. Finally, we verified the superior self-healing ability of the alternating copolymer compared to that of the corresponding 1 : 1 statistical copolymer. 相似文献
100.
The efficient selective synthesis of secondary and tertiary amines has been achieved by means of Cp*Ir-catalyzed multialkylation of ammonium salts with alcohols without solvent: the reactions of ammonium acetate with alcohols gave tertiary amines exclusively, while those of ammonium tetrafluoroborate afforded secondary amines selectively. Using this method, secondary 5- and 6-membered cyclic amines were synthesized from ammonium tetrafluoroborate and diols in one pot. 相似文献