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991.
Susumu Iwabuchi Yasaku Watanabe Takayuki Nakahira Kuniharau Kojima 《Journal of polymer science. Part A, Polymer chemistry》1979,17(6):1721-1726
Tri-n-butylborane (TBB) was found to be capable of initiating the copolymerization of vinylhydroquinone (VHQ) with maleic anhydride (MAn) and diethyl fumarate (DEF) in cyclohexanone at 30°C under nitrogen. Redox potentials of the VHQ–MAn copolymer obtained were examined. These results, along with spectroscopic data, indicate that the copolymers are of a highly alternating character. 相似文献
992.
The 5-substituted 4-methoxycarbonyloxazole derived from L-serine derivative using diphenyl phosphorazidate (DPPA) has been converted to a 2,4-diaminosugar antibiotic, prumycin. 相似文献
993.
Nakamura T Motoyama T Hirokawa T Hirono S Yamaguchi I 《Chemical & pharmaceutical bulletin》2003,51(11):1293-1298
Homology modeling was used to construct a model of the three-dimensional structure of pentachlorophenol 4-monooxygenase (PcpB). A PSI-BLAST homology search was initially performed to identify the 3D structure of proteins homologous with PcpB. The feasibility of modeled structures of PcpB was evaluated by Verify3D, which calculated structural compatibility scores based on 3D-1D profiles. The predicted structure of PcpB had an acceptable 3D-1D self-compatibility score, beyond the incorrect fold score threshold. A PcpB-pentachlorophenol (PCP) complex was then constructed utilizing the modeled PcpB structure. After energy minimization of the complex, and successive minimizations of the system that consisted of the complex and the water layer surrounding the complex, the molecular dynamics of the system were simulated. The active-site residues of PcpB were identified on the basis of the modeled structure, and PcpB mutants were then designed to change the active site residues, expressed, and purified by affinity chromatography. The mutant activity was compared with that of the wild-type to investigate the validity of the modeled structure. The experimental results suggested that Phe85, Tyr216, and Arg235 were relevant to enzyme activity, and that Tyr397 and Phe87 were important for stabilization of the structure of PcpB. 相似文献
994.
Felix W. W. Hartrampf Takayuki Furukawa Prof. Dr. Dirk Trauner 《Angewandte Chemie (International ed. in English)》2017,56(3):893-896
An enantioselective total synthesis of the Lycopodium alkaloid lycoposerramine R is presented. It relies on a base-mediated cyclization that resembles the Conia-ene reaction of ynones and gold-catalyzed variants thereof. Thus, hydrindanones and other functionalized ring systems bearing an exocyclic alkene can be rapidly accessed at room temperature without noble metal catalysis or substrate preactivation. 相似文献
995.
Yuichi Hirai Dr. Takayuki Nakanishi Dr. Yuichi Kitagawa Dr. Koji Fushimi Dr. Tomohiro Seki Prof. Dr. Hajime Ito Prof. Dr. Yasuchika Hasegawa 《Angewandte Chemie (International ed. in English)》2017,56(25):7171-7175
Luminescence upon the grinding of solid materials (triboluminescence, TL) has long been a puzzling phenomenon in natural science and has also attracted attention because of its broad application in optics. It has been generally considered that the TL spectra exhibit similar profiles as those of photoluminescence (PL), although they occur from distinct stimuli. Herein, we describe for the first time a large spectral difference between these two physical phenomena using lanthanideIII coordination polymers with efficient TL and PL properties. They are composed of emission centers (TbIII and EuIII ions), antenna (hexafluoroacetylacetonate=hfa), and bridging ligands (2,5-bis(diphenylphosphoryl)furan=dpf). The emission color upon grinding (yellow TL) is clearly different from that upon UV irradiation (reddish-orange PL) in TbIII/EuIII-mixed coordination polymers [Tb,Eu(hfa)3(dpf)]n (Tb/Eu=1). The results directly indicate the discrete excitation processes of PL and TL. 相似文献
996.
Hiroshi Suzuki Sigeo Kida Takayuki Nakamae Kenjiro Suzuki 《International Journal of Heat and Fluid Flow》1991,12(4):353-359
A study was made to see if it is possible to enhance the heat transfer in the downstream region of a backward-facing step, where heat transfer is normally deteriorated, by the insertion of a cylinder near the top corner of the step. Cylinder size and streamwise position of the cylinder were kept constant but the cross-stream position of the cylinder was changed in three steps. Results of the heat transfer experiment, flow visualization, and measurement of the averaged and fluctuating flow fields were reported. When the cylinder was mounted at a position, a little higher than the top surface of the step, a jet-like flow pattern emerged in the averaged velocity profile beneath the cylinder and the recirculating flow was intensified. Therefore, the velocity of recirculating flow near the wall is increased at some streamwise positions. Additionally, the velocity fluctuation was intensified not only in the shear layer between the jet-like flow and the recirculating flow regions but also in the near wall region, resulting in the effective augmentation of heat transfer in this case. Therefore, it is concluded that the mounting of a cylinder is effective in the enhancement of deteriorated heat transfer in the recirculating flow region, if its is mounted in a proper position. 相似文献
997.
Mathematical Programming - In this paper, we propose a primal-dual path following method for nonlinear semi-infinite semi-definite programs with infinitely many convex inequality constraints,... 相似文献
998.
Tomoki Komiyama Yoko Harada Takayuki Hase Sota Mori Dr. Shinya Kimura Dr. Masashi Yokoya Prof. Dr. Masamichi Yamanaka 《化学:亚洲杂志》2021,16(13):1750-1755
Urea derivatives that were substituted with a 2-benzylphenyl group and an alkyl group functioned as low molecular weight gelators for various organic solvents and ionic liquids. Urea derivatives with long alkyl chains were effective for the gelation of polar solvents. However, they were not suitable for the gelation of non-polar solvents, whereas urea derivatives with short alkyl chains were effective. Ionic liquids were similar to polar solvents in that urea derivatives with long alkyl chains were the most effective gelators. The physical properties of the formed supramolecular gels were analyzed by dynamic viscoelasticity measurements using a rheometer. 相似文献
999.
Crystal Structures and Redox Responses Coupled with Ion Recognition of p‐Benzoquinone‐ and Hydroquinone‐Fused [18]crown‐6
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Takayuki Kobayashi Yuta Nakane Dr. Takashi Takeda Dr. Norihisa Hoshino Prof. Hidetoshi Kawai Prof. Tomoyuki Akutagawa 《化学:亚洲杂志》2015,10(2):390-396
The crystal structures and redox properties of p‐benzoquinone (BQ)‐fused [18]crown‐6 1 and bis‐BQ‐fused [18]crown‐6 2 were examined. The anion radicals of these BQ molecules were stabilized by addition of metal ions, through effective electrostatic interactions between the negatively charged BQ moiety and positively charged ion‐capturing [18]crown‐6 unit. The electrostatic interactions and solvation energy played important roles in determining the magnitudes of anodic redox shifts in the reduction potentials. Regular π‐stacking of BQ units and regular arrays of [18]crown‐6 units were observed in crystal 2 , in which one‐dimensional π‐electron columns were separated by ionic channels. The hydroquinone‐fused [18]crown‐6 molecule 3 and a new BQ‐ and phenol‐fused [18]crown‐6 derivative 4 were obtained as single crystals. The molecular conformations of [18]crown‐6 in crystal 3 and hydrated crystal 3 ?H2O were different from each other. 相似文献
1000.