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991.
Hide-Ki Ishida Hideharu Ishida Makoto Kiso Akira Hasegawa 《Tetrahedron: Asymmetry》1994,5(12):2493-2512
The first total synthesis of ganglio-series gangliosides GQ1b, GT1b and GD1b, which contain α-sialyl-(2→8)-α-sialic acid residue in the structure, will be described. Glycosylation of 2-(trimethylsilyl)ethyl O-(2-acetamido-6-O-benzyl-2-deoxy-3,4-O-iso-propylidene-β-
-galactopyranosyl)-(1→4)-O-(2,6-di-O-benzyl-β-
-galactopyranosyl)-(1→4)-2,3,6-tri-O-benzyl-β-D-glucopyranoside (7) with methyl [phenyl 5-acetamido-8-O-(5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-
-glycero-α-
-galacto-2-nonulopyranosylono-1′,9-lactone)-4,7-di-O-acetyl-3,5-dideoxy-2-thio-
-glycero-
-galacto-2-nonulopyranosid]onate (8) using N-iodosuccinimide (NIS)-trifluoromethanesulfonic acid (TfOH) in acetonitrile gave the protected GD2 pentasaccharide 9, which was converted into the pentasaccharide acceptor 10 by de-O-isopropylidenation. Glycosylation of 10 with methyl thioglycoside derivatives 18, 26, 34 by use of dimethyl(methylthio)sulfonium triflate (DMTST) gave the protected ganglioside oligosaccharides 19, 27 and 35, respectively. Compounds 9, 19, 27 and 35 were transformed into the corresponding α-trichloroacetimidates 13, 22, 30 and 38, via reductive removal of benzyl groups, O-acetylation, selective removal of 2-(trimethylsilyl)ethyl group, and treatment of trichloroacetonitrile. Condensation of the imidates 13, 22, 30 and 38 with (2S,3R,4E)-2-azido-3-O-benzoyl-4-octadecene-1,3-diol (14) gave the corresponding β-glycosides 15, 23, 31 and 39, which were converted, via selective reduction of azido group, coupling with octadecanoic acid, de-O-acylation, and saponification of methyl esters and lactone groups, into the corresponding gangliosides GD2 (17), GD1b (25), GT1b (33) and GQ1b (41). 相似文献
992.
Kinetic study of C2H4 polymerization on reduced V2O5/Al2O3 catalysts revealed that the rate equation can be expressed as V=k exp (-Y) KaPE/(1+KaPE) in the temperature range of –20 to 70°C. The deactivation constant, , was found to have a close relation with the yield and molecular weight of the polymer. C2H4 V2O5/Al2O3 –20 +70°C : Vp=k·exp(-Yp)·KaPe/(1+KaPe). . 相似文献
993.
Makoto Ishida Shinji Tsuji Katsutaka Kimura Hiroyuki Matsunami Tetsuro Tanaka 《Journal of Crystal Growth》1978
Thin films of PLZT were epitaxially grown at around 700°C on sapphire and SrTiO3 substrates: (111) PLZT (0001) sapphire and (100) PLZT (100) SrTiO3. PLZT films on semiconductor substrates were also grown at around 620°C. The crystal quality of these PLZT films was investigated by X-ray diffraction, reflection electron diffraction, scanning electron microscopy (SEM), and Auger electron spectroscopy (AES). The epitaxy of PLZT films grown on different single crystal substrates is discussed. The refractive index of the film on the sapphire substrate was determined as 2.497 by an optical waveguide technique. 相似文献
994.
995.
K. Nagamine K. Ishida S. Sakamoto Y. Watanabe T. Matsuzaki 《Hyperfine Interactions》1993,82(1-4):343-353
Among a series of X-ray experiments on the muon catalyzed fusion (CF) carried out by using pulsed muons at UTMSL/KEK, a direct knowledge of -sticking probability (
s) in CF of high density D-T mixture with high T concentration has been obtained by measuring a characteristic muonic X-ray from the () atoms (central energy of 8.2 keV with a correct Doppler broadening). Combining with the recent X-ray measurements in (d) to3He and4He impurities, new insight is now obtained for the detailed background structure in the X-ray spectrum, suggesting the future direction for the X-ray measurements. 相似文献
996.
Mori M Nojiri MM Hirata KS Kihara K Oyama Y Suzuki A Takahashi K Yamada M Takei H Koga M Miyano K Miyata H Fukuda Y Hayakawa T Inoue K Ishida T Kajita T Koshio Y Nakahata M Nakamura K Sakai A Sato N Shiozawa M Suzuki J Suzuki Y Totsuka Y Koshiba M Nishijima K Kajimura T Suda T Suzuki AT Hara T Nagashima Y Takita M Yokoyama H Yoshimoto A Kaneyuki K Takeuchi Y Tanimori T Tasaka S Nishikawa K 《Physical review D: Particles and fields》1993,48(12):5505-5518
997.
998.
Neocarzinostatin: selective tryptophan oxidation and neocarzinostatin-chromophore binding to apo-neocarzinostatin 总被引:1,自引:0,他引:1
K Edo K Saito Y Matsuda Y Akiyama-Murai M Mizugaki Y Koide N Ishida 《Chemical & pharmaceutical bulletin》1991,39(1):170-176
Neocarzinostatin (NCS), an antitumor protein antibiotic, is composed of apo-neocarzinostatin (apo-NCS) and neocarzinostatin-chromophore (NCS-chr), the principle of the biological activities of NCS. Apo-NCS having two tryptophan (Trp) residues at positions (39 and 83) was chemically modified by N-bromosuccinimide in a study on the correlation of the binding site(s) of NCS-chr. Selective oxidation of Trp residues was observed when NCS was titrated with N-bromosuccinimide. In contrast, non-selective oxidation of the two Trps on apo-NCS was observed and both Trp (39 and 83) of apo-NCS were titrated with N-bromosuccinimide. After selective oxidation, the remaining Trp residue of NCS was assigned as Trp (83). These results clearly indicate that the Trp (83) residue of apo-NCS changed from the "reactive type" to the "non-reactive type" after the binding of NCS-chr with apo-NCS. The fluorescence emission intensity of apo-NCS generated from the Trp (39) residue was quenched by NCS-chr. These data suggest that NCS-chr directly interacts with the Trp (39) residue and that a beta-sheeted loop containing the Trp (83) residue of apo-NCS changes the high-order structure upon binding with NCS-chr. 相似文献
999.
Extra‐Large Mechanical Anisotropy of a Hydrogel with Maximized Electrostatic Repulsion between Cofacially Aligned 2D Electrolytes
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Koki Sano Yuka Onuma Arazoe Dr. Yasuhiro Ishida Dr. Yasuo Ebina Prof. Dr. Minoru Osada Prof. Dr. Takayoshi Sasaki Dr. Takaaki Hikima Prof. Dr. Takuzo Aida 《Angewandte Chemie (International ed. in English)》2018,57(38):12508-12513
In our previous work, we have shown that “electrostatic forces”, when generated anisotropically in aqueous media by 2D electrolytes upon cofacial orientation, enable the formation of a hydrogel with an anisotropic parameter, as defined by the ratio of elastic moduli E⊥/E∥, of 3.0. Herein, we successfully developed the design strategy for a hydrogel with an anisotropic parameter of no less than 85. This value is not only 28 times greater than that of our previous anisotropic hydrogel but also 6 times larger than the current champion record in synthetic hydrogels (E⊥/E∥~15). Firstly, we simply lowered ionic contaminants in the hydrogel and were able to enhance the anisotropic parameter from 3.0 to 18. Then, we chose a supporting polymer network allowing the hydrogel to carry a higher interior permittivity. Consequently, the anisotropic parameter was further enhanced from 18 to 85. Owing to the enhanced mechanical anisotropy, our new hydrogel displayed a superb ability of seismic isolation. 相似文献
1000.
Koki Sano Dr. Yasuhiro Ishida Prof. Dr. Takuzo Aida 《Angewandte Chemie (International ed. in English)》2018,57(10):2532-2543
Owing to their water‐rich structures, which are similar to those of biological tissues, hydrogels have long been regarded as promising scaffolds for artificial tissues and organs. However, in terms of the structural anisotropy, most synthetic hydrogels are substantially different from biological systems. Synthetic hydrogels are usually composed of randomly oriented three‐dimensional polymer networks whereas biological systems adopt anisotropic structures with hierarchically integrated building units. Such anisotropic structures often play essential roles in biological systems to exhibit particular functions. In this context, anisotropic hydrogels provide an entry point for exploring biomimetic applications of hydrogels. Reflecting these aspects, an increasing number of studies on anisotropic hydrogels have been reported recently. This Minireview highlights the use and perspectives of these anisotropic hydrogels, particularly focusing on their preparation, structures, and applications. 相似文献