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991.
Toshiyuki Furutani Masakatsu Furui Takao Mori Takeji Shibatani 《Applied biochemistry and biotechnology》1996,59(3):319-328
An emulsion bioreactor for production of (2R,3S)-3-(4-methoxyphenyl) glycidic acid methyl ester ([-]MPGM) from a racemic mixture ([±]MPGM) using the lipase fromSerratia marcescens has been proposed. Kinetics of hydrolyzing reaction and purification of (-)MPGM from the reaction mixture were investigated
to provide a basis for industrial application of this bioreactor. The hydrolyzing reaction in the bioreactor proceeded at
a rate that was first order in substrate concentration. The reaction rate was affected by a stirring speed and the ratio of
the aqueous phase containing lipase to the toluene phase containing substrate. Phase separation after the enzymatic reaction
was accomplished by addition of surfactant to the reaction mixture, and crystalline (-)MPGM with a chemical purity of 100%
and optical purity of 100% enantiomeric excess was obtained in a high yield of 40–43% by concentration of the toluene solution. 相似文献
992.
The highly stereoselective synthesis of the AB-ring system of macquarimicins, a novel class of microbial metabolites with inhibitory activity for neutral sphingomyelinase, has been achieved. The present synthesis features the highly stereocontrolled construction of the cis-tetrahydroindan structure via the intramolecular Diels-Alder reaction of an (E,Z,E)-1,6,8-nonatriene derived from D-glyceraldehyde acetonide. Reaction: see text. 相似文献
993.
Hiromitsu Kozuka Shinsuke Takenaka Hiroshi Tokita Toshihiro Hirano Yugo Higashi Takao Hamatani 《Journal of Sol-Gel Science and Technology》2003,26(1-3):681-686
Residual stress was evaluated by measuring the substrate curvature for alkoxide-derived silica and titania films deposited on silica glass substrates. The residual stress was tensile, increasing with increasing heat-treatment temperature. The stress in fired films was affected greatly by water/alkoxide ratio and chelating agents in starting solutions. Secondly, in situ observation was made on cracking of gel films subjected to heat-treatment. Silica and titania gel films deposited on silicon wafers were cracked in the heating-up stage at temperatures of 100°–400°C, depending on the film thickness and heating rate. Larger thickness and lower heating rates were found to lower the cracking onset temperature. Finally, organic polymers with amide groups were demonstrated to increase the uncracking critical thickness. The polymers include polyvinylpyrrolidone and polyvinylacetamide, allowing single layer ceramic coating films over 1 m in thickness to be formed without cracking. 相似文献
994.
Sakuda S Sugiyama Y Zhou ZY Takao H Ikeda H Kakinuma K Yamada Y Nagasawa H 《The Journal of organic chemistry》2001,66(10):3356-3361
Allosamizoline (1) is an aminocyclitol component of allosamidin, a Streptomyces metabolite, and has a cyclopentane ring originated from D-glucosamine. Biosynthesis of the cyclopentane ring was studied by feeding experiments with a variety of deuterium-labeled glucosamine and glucose. In the feeding experiments with [3-(2)H]- and [4-(2)H]-D-glucosamine and [1-(2)H]-D-glucose, deuterium was incorporated into C-3, C-4, and C-1 of 1, respectively. On the other hand, feeding experiments with [5-(2)H]- and [6,6-(2)H(2)]-D-glucosamine showed that deuterium on C-5 and one of the two deuterium atoms on C-6 of glucosamine were lost during the cyclopentane ring formation of 1. In the feeding experiments with (6R)- and (6S)-[6-(2)H(1)]-D-glucose, the (6R)-deuterium of glucose was incorporated into the proS position on C-6 of 1, but the (6S)-deuterium of glucose was not incorporated into 1. These results suggested that an intermediate with a 6-aldehyde group is involved in the biosynthesis of the cyclopentane ring moiety of 1 and overall inversion of stereochemistry of the C-6 methylene group occurred by stereospecific oxidation and reduction on C-6 during the formation of 1. The 6-aldehyde intermediate may play a key role in the biosynthetic step(s) of cyclization to form the cyclopentane ring and/or deoxygenation at C-5. 相似文献
995.
[reaction: see text] A practical method for the synthesis of optically active styrene oxides has been developed via formation of optically active 2-chloro-1-phenylethanols generated by reductive transformation of ring-substituted 2-chloroacetophenones. The optically active alcohols with up to 98% ee are obtainable from the asymmetric reduction of acetophenones with an S/C = 1000-5000 with a formic acid triethylamine mixture containing a well-defined chiral Rh complex, CpRhCl[(R,R)-Tsdpen]. 相似文献
996.
Chyongjin Pac Takao Fukunaga Yoshikazu Go-An Toshiyuki Sakae Shozo Yanagida 《Journal of photochemistry and photobiology. A, Chemistry》1987,41(1)
We have attempted to explore mechanistic aspects of the photosensitized ring-cleavage reactions of cis-1,2-diphenylcyclobutane (1), cis-transoid-cis-cyclobutal[1,2-a:4,3-a′] diindene (2) and r-1,c-2-dimethyl-t-3,t-4-di(4-methoxyphenyl)cyclobutane (3) by electron acceptors (A) in acetonitrile. The experimental results demonstrate that the ring cleavage of 1 and 2 occurs as a consequence of the rapid geminate recombination of ion-radical pairs occurring at a rate of well over 109 s−1 without ionic dissociation. In the case of 3, however, the photoreactions proceed by way of a chain-reaction mechanism involving the free cation radical of 3 which undergoes ring cleavage at much less than 107 s−1. The rapid ring cleavage of 1+ and 2+ is attributed to significant perturbations of the cyclobutane ring by the population of positive charge on the orbital array of the two π-electron systems and the cyclobutane-ring σ framework because of strong through-bond couplings. It is presumed that the cyclobutane ring of 3+ is much less distorted since the positive charge is mostly localized on the aryl group. The rapid geminate recombination of the A−−−1+ and A−−−2+ pairs is discussed in terms of a very efficient transition from the “distorted” and “ring-opened” minima of the A−−−D+ surface to the A–D surface. In the case of 3, this mechanism cannot be expected to operate in the geminate recombination. 相似文献
997.
From a MeOH extract of the aerial part of Piper futokadsura, the tetrahydrofuran lignans, futokadsurin A [(7S,8S,7'S,8'R)-3,4,3'-trimethoxy-4'-hydroxy-7,7'-epoxylignan], futokadsurin B [(7R,8R,7'R,8'S)-3,4-dimethoxy-3',4'-methylenedioxy-7,7'-epoxylignan], and futokadsurin C [(7R,8R,7'S,8'S)-3,4-methylenedioxy-3',4'-dimethoxy-7,7'-epoxylignan] were isolated, together with nine known neolignans. In addition, L-tryptophan, pellitorine, phytol, elemicin, and 1,2,4-trimethoxyphenyl-5-aldehyde were isolated. The structures of the new compounds were elucidated using spectroscopic methods. These lignans inhibited nitric oxide production by a murine macrophage-like cell line (RAW 264.7), which was activated by lipopolysaccharide and interferon-gamma. 相似文献
998.
Photoelectron emission and XPS studies of real iron surfaces subjected to scratching in air,water, and organic liquids 下载免费PDF全文
Yoshihiro Momose Keika Tsuruya Takao Sakurai Keiji Nakayama 《Surface and interface analysis : SIA》2016,48(4):202-211
The influence of temperature and surface overlayer on the photoelectron emission from scratched real iron surfaces was investigated using thermally assisted photoelectron emission (TAPE) and X‐ray photoelectron spectroscopy (XPS) measurements. The scratching was conducted with a diamond cutter in seven atmospheres. The intensity of TAPE as a function of temperature, called glow curve, was measured in the range 25–339 °C using a Geiger counter under ultraviolet irradiation at 210 nm. The temperature was scanned in two cycles (Up1 and Down1, and Up2 and Down2). The XPS measurements were carried out at 25 °C and after TAPE measurements at 200 and 339 °C. The photoelectron emission intensity at 40 °C in the Up1 scan increased in the order of air < water ≈ methanol ≈ cyclohexane < ethanol < benzene < acetone, and then each glow curve exhibited a gradual increase with temperature through a broad peak. It was found that the dependence of the emission intensity in the Up1 scan on the oxygen component ratio, ZO = O2?/(OH? + O2?) and the percentage of the Fe metal and FeOOH components of the Fe3p spectra for the atmospheres greatly differed. Additionally, the glow curve in the Up1 scan was completely different from that in the other scans. It was proposed that the photoelectron emission in the Up1 scan originates from not only the base metal but also the surface overlayer having trapped electrons and is strongly influenced by the acid–base interaction of the surface hydroxyl groups with the liquids molecules. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
999.
Usefulness of Mesoporous Silica as a Template for the Preparation of Bundles of Bi Nanowires with Precisely Controlled Diameter Below 10 nm 下载免费PDF全文
Masaki Kitahara Hasbuna Kamila Prof. Dr. Atsushi Shimojima Prof. Dr. Hiroaki Wada Prof. Dr. Takao Mori Prof. Dr. Ichiro Terasaki Prof. Dr. Kazuyuki Kuroda 《化学:亚洲杂志》2016,11(6):900-905
The reduction of the diameter of Bi nanowires below 10 nm has been an important target because of the theoretical prediction with regard to significant enhancement in thermoelectric performance by size reduction. In this study, we have demonstrated the usefulness of mesoporous silica with tunable pore size as a template for the preparation of thin Bi nanowires with diameters below 10 nm. Bi was deposited within the templates through a liquid phase deposition using hexane and 1,1,3,3‐tetramethyldisiloxane as a solvent and reducing agent, respectively. Bundles of thin Bi nanowires with non‐crystalline frameworks were successfully obtained after the template removal. The diameter was precisely controlled between about 6 nm and 9 nm. The judicious choices of mesoporous silica and deposition conditions are critical for the successful preparation. The reliable formation of such thin Bi nanowires reported here opens up exciting new possibilities. 相似文献
1000.
Preparation and Characterization of Nano-structured Ceramic Powders Synthesized by Emulsion Combustion Method 总被引:7,自引:0,他引:7
Takatori Kazumasa Tani Takao Watanabe Naoyoshi Kamiya Nobuo 《Journal of nanoparticle research》1999,1(2):197-204
The emulsion combustion method (ECM), a novel powder production process, was originally developed to synthesize nano-structured metal-oxide powders. Metal ions in the aqueous droplets were rapidly oxidized by the combustion of the surrounding flammable liquid. The ECM achieved a small reaction field and a short reaction period to fabricate the submicron-sized hollow ceramic particles with extremely thin wall and chemically homogeneous ceramic powder. Alumina, zirconia, zirconia–ceria solid solutions and barium titanate were synthesized by the ECM process. Alumina and zirconia powders were characterized to be metastable in crystalline phase and hollow structure. The wall thickness of alumina was about 10nm. The zirconia–ceria powders were found to be single-phase solid solutions for a wide composition range. These powders were characterized as equiaxed-shape, submicron-sized chemically homogeneous materials. The powder formation mechanism was investigated through the synthesis of barium titanate powder with different metal sources. 相似文献