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81.
Racemic α-monosubstituted cyclopentanones were converted to optically active forms by a thermodynamically controlled deracemization using TADDOL-type host molecule 1 in alkaline aqueous MeOH. The efficiency of this conversion was strongly influenced by the ratio of the solvent components (H2O/MeOH) and the functionality and architecture of the α-side-chain on the cyclopentanones. For example, (R)-2-(2-benzyloxyethyl)cyclopentanone (9) was obtained in 89% yield with 97% ee using a 7:3 mixture of H2O/MeOH as the solvent. X-ray analytical studies were also carried out and disclosed the nature of this chiral molecular recognition process in the solid phase. 相似文献
82.
Sode Koji Sugiura Hiroto Tsugawa Wakako Watazu Yoshihumi Hamafuji Tetsuro 《Applied biochemistry and biotechnology》2000,84(1-9):947-954
A novel enzymatic organic synthesis was reported, utilizing glucose-3-dehydrogenase (G3DH) and its regeneration via electrochemical
methods. We combined the water-soluble G3DH prepared from a marine bacterium, Halomonas sp. α-15, and electron mediator with the electrode system in order to regenerate the enzyme. Using this system, the conversion
of 1,5-anhydro-d-glucitol (1,5AG), a diabetes marker in human blood, was investigated. The final yield of the product, 3-keto anhydroglucitol
(3-ketoAG), which was identified by 13C nuclear magnetic resonance, was 82% based on the initial amount of 1,5AG. The electrochemical yield of the reaction proceeded
almost stoichiometrically. The electrochemical conversion rate of 1,5AG was 1.24 mmol/(L·h), and the electrochemical yield
of 1,5AG consumption was 80%, whereas that for 3-ketoAG was 60%. 相似文献
83.
Shouhei Toyoda Yoshifumi Yamaguchi Masataka Hiwatashi Yasuhiko Tomonari Hiroto Murakami Dr. Naotoshi Nakashima Prof. 《化学:亚洲杂志》2007,2(1):145-149
We designed and synthesized 4‐dodecyloxybenzenediazonium tetrafluoroborate ( 1 ), which preferentially reacts with metallic single‐walled carbon nanotubes (SWNTs) by kinetic control. We first determined the suitable experimental conditions for the preferential reaction of 1 with individually dissolved SWNTs by monitoring the decrease in absorbance for the metallic SWNT in the range of 400–650 nm in the absorption spectrum of the SWNTs. The reacted SWNTs were thoroughly rinsed with THF to obtain THF‐insoluble SWNTs. The Raman spectrum of the THF‐insoluble SWNTs showed a strong peak near 180 cm?1, which corresponds to a semiconducting breathing band. The metallic breathing bands (≈220 cm?1) and Breit–Wingner–Fano (BWF) modes (1520 cm?1) corresponding to the metallic SWNTs were much weaker than those of the pristine SWNTs. We also confirmed that metallic peaks in the range of 400–650 nm in the absorption spectrum of THF‐insoluble SWNTs that were individually dissolved in an aqueous micelle of sodium cholate were almost nondetectable. All the results indicate that the THF‐insoluble SWNTs are semiconducting. 相似文献
84.
Tadatomi Nishikubo Atsushi Kameyama Hiroto Kudo Kousuke Tsutsui 《Journal of polymer science. Part A, Polymer chemistry》2002,40(9):1293-1302
New photoreactive calixarene derivatives containing spiro ortho ester groups (calixarenes 3a–3c ) were synthesized by the reaction of 2‐bromomethyl‐1,4,6‐trioxaspiro[4.4]nonane with 2,8,14,20‐tetramethyl‐4,6,10,12,16,18,22,24‐octakis(carboxymethoxy)calix[4]resorcinarene, 5,11,17,23,29,35‐hexamethyl‐37,38,39,40,41,42‐hexakis(carboxymethoxy)calix[6]arene, and 5,11,17,23,29,35,41,47‐octa‐tert‐butyl‐49,50,51,52, 53,54,55,56‐octakis‐(carboxymethoxy)calix[8]arene, which were prepared by the reaction of C‐methylcalix[4]resorcinarene, p‐methylcalix[6]arene, and p‐tert‐butylcalix[8]arene, respectively. The thermal stability of the obtained calixarene derivatives containing spiro ortho ester groups was examined with thermogravimetric analysis, and it was found that these calixarene derivatives had good thermal stability. The photoinitiated cationic polymerization of spiro ortho ester groups in calixarene derivatives 3a–3c was examined with certain photoacid generators in the film state. Interestingly enough, the reaction of calixarene derivatives did not proceed with only photoirradiation; however, the reaction proceeded smoothly when the photoirradiation was followed by heating. Furthermore, calixarene 3a , composed of a C‐methylcalix[4]resorcinarene structure, showed the highest photochemical reactivity in this reaction system. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1293–1302, 2002 相似文献
85.
A. Ishii T. Itoh Y. Kodera A. Matsushima M. Hiroto H. Nishimura Y. Inada 《Research on Chemical Intermediates》1997,23(8):683-689
Chlorophyll a was adsorbed onto freeze-dried bentonite to form chlorophyll-bentonite conjugate, which was photostable against light illumination [1]. Physiological function of chlorophyll-bentonite conjugate is explored; increasing the amount of chlorophyll adsorbed onto bentonite leads to enhancement of the photostability accompanied with shifting the absorbance maximum to longer wavelength. Furthermore, the conjugate exhibits a high photoreduction ability of nitro blue tetrazolium, NBT, through the formation of superoxide anion without any loss of photosensitive activity even after 50 hr illumination. 相似文献
86.
87.
Matsunaga Hiroki Katoh Katsumi Habu Hiroto Noda Masaru Miyake Atsumi 《Journal of Thermal Analysis and Calorimetry》2019,135(5):2677-2685
Journal of Thermal Analysis and Calorimetry - This paper focuses on the thermal behavior of mixtures of ammonium dinitramide (ADN) and amine nitrates. Because some mixtures of ADN and amine nitrate... 相似文献
88.
Tachikawa H Fukuzumi T Inaoka K Koyano I 《Physical chemistry chemical physics : PCCP》2010,12(47):15399-15405
The ion-molecule reaction, CH(3)CN(+) + CH(3)CN → CH(3)CNH(+) + CH(2)CN, has been investigated using the threshold electron-secondary ion coincidence (TESICO) technique. Relative reaction cross sections for two microscopic reaction mechanisms, i.e., proton transfer (PT) from the acetonitrile ion CH(3)CN(+) to neutral acetonitrile CH(3)CN and hydrogen atom abstraction (HA) by CH(3)CN(+) from CH(3)CN, have been determined for two low-lying electronic states, (2)E and (2)A(1) of the CH(3)CN(+) primary ion. The cross section for PT of the (2)A(1) state was smaller than that of the (2)E state, whereas that of HA are almost the same in the two states. Ab initio calculations showed that the dissociation of the C-H(+) bond of CH(3)CN(+) is easier in the (2)E state than that in the (2)A(1) state. The direct ab initio molecular dynamics (MD) calculations showed that two mechanisms, direct proton transfer and complex formation, contribute the reaction dynamics. 相似文献
89.
Yoshida H Fukushima H Ohshita J Kunai A 《Journal of the American Chemical Society》2006,128(34):11040-11041
A zwitterion, generated from an aryne and an imine, has been demonstrated to serve as an excellent molecular scaffold for capturing CO2, which results in the straightforward formation of diverse benzoxazinones. 相似文献
90.
We propose a new expression of a line-shape function (LSF) including the effects of changes in both force constants and the molecular structure within the harmonic-oscillator approximation. This expression enables us to calculate the LSF using only the data on molecular structures, force constants, and electronic energies in the initial and final electronic states without solving the eigenvalue equation for the normal vibration of a molecule. To derive the LSF expression, we consider one-photon emission from a polyatomic molecule thermalized in an electronic excited state, and derive the intensity distribution function for one-photon emission using not Lax and Kubo and Toyozawa's [J. Chem. Phys. 20, 1752 (1952); Prog. Theor. Phys. 13, 160 (1955)] generating function method but rather the density-matrix method. As a simple application, a Gaussian approximate LSF is applied to SO(2). As a result, it is found that the effect of change in force constants between the initial and final electronic states cannot be ignored, nor can the effect of change in the molecular structure between these two states. The LSF expression obtained is applicable to studies of not only radiative transition but also of electron-transfer and energy-transfer processes where both changes in molecular structure and force constants between the initial and final electronic states cannot be disregarded. 相似文献