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141.
Jun Nishimura Tomohisa Okuda Yoshihiko Mukai Hidetoshi Hashiba Akira Oku 《Tetrahedron letters》1984,25(14):1495-1498
1,3-bis(4-vinylnaphthyl)propane and 1-(4-vinylnaphthyl)-3-(-vinylphenyl)propane, were cyclocodimerized with indene to afford indenyl-substituted [3.3](1,4)naphthalenophanes and [3.3]paracyclo(1,4)naphthalenophanes. 相似文献
142.
Tuyet TM Harada T Hashimoto K Hatsuda M Oku A 《The Journal of organic chemistry》2000,65(5):1335-1343
Sequential etherification of 2,2',6,6'-tetrahydroxybiphenyl (1) with 1,4-di-O-benzyl-L-threitol under Mitsunobu conditions gives desymmetrized biphenyldiol 9 of S-axial chirality exclusively. Cyclization of 9 with 1,omega-dibromoalkanes followed by removal of the chiral auxiliary yields (S)-2,2'-biphenyldiols 14 with alkylenedioxy bridges at the 6 and 6' positions. (S)-6,6'-Dialkyl- and -diphenyldiols 20 are obtained in an efficient manner via Pd(0)-catalyzed cross-coupling of bis(triflate) derivative 17 with organozinc reagents. Bis(triflate) 17 also serves as an intermediate for asymmetric synthesis of axially chiral biphenyldicarboxylic acid 23, terphenylcarboxylic acid 28, lactone 26, and lactam 30. 相似文献
143.
Wang X Adachi S Iwai H Takatsuki H Fujita K Kubo M Oku A Harada T 《The Journal of organic chemistry》2003,68(26):10046-10057
allo-Threonine-derived O-aroyl-B-phenyl-N-tosyl-1,3,2-oxazaborolidin-5-ones 1g,n catalyze the asymmetric Mukaiyama-Michael reaction of acyclic enones with a trimethylsilyl ketene S,O-acetal in high enantioselectivity. A range of alkenyl methyl ketones is successfully employed as Michael acceptors affording ee values of 85-90% by using 10 mol % of the catalyst. The use of 2,6-diisopropylphenol and tert-butyl methyl ether as additives is found to be essential to achieve high enantioselectivity in these reactions. The effects of the additives are discussed in terms of the retardation of an Si(+)-catalyzed racemic pathway, which seriously deteriorates the enantioselectivity of asymmetric Mukaiyama-Michael reactions. A working model for asymmetric induction is proposed based on correlation between catalyst structures and enantioselectivities. 相似文献
144.
Oku M Hou Y Xing X Reed B Xu H Chang C Ng CY Nishizawa K Ohshimo K Suzuki T 《The journal of physical chemistry. A》2008,112(11):2293-2310
We have studied 3s(n-1 and pi-1) Rydberg states and D0(n-1) and D1(pi-1) cationic states of pyrazine [1,4-diazabenzene] by picosecond (2 + 1) resonance-enhanced multiphoton ionization (REMPI), (2 + 1) REMPI photoelectron imaging, He(I) ultraviolet photoelectron spectroscopy (UPS), and vacuum ultraviolet pulsed field ionization photoelectron spectroscopy (VUV-PFI-PE). The new He(I) photoelectron spectrum of pyrazine in a supersonic jet revealed a considerably finer vibrational structure than a previous photoelectron spectrum of pyrazine vapor. We performed Franck-Condon analysis on the observed photoelectron and REMPI spectra in combination with ab initio density functional theory and molecular orbital calculations to determine the equilibrium geometries in the D0 and 3s(n-1) states. The equilibrium geometries were found to differ slightly between the D0 and 3s states, indicating the influence of a Rydberg electron on the molecular structure. The locations of the D1-D0 and 3s(pi-1)-3s(n-1) conical intersections were estimated. From the line width in the D1 <-- S0 spectrum, we estimated the lifetime of D1 to be 12 fs for pyrazine and 15 fs for fully deuterated pyrazine. A similar lifetime was estimated for the 3s(pi-1) state of pyrazine by REMPI spectroscopy. The vibrational feature of D1 observed in the VUV-PFI-PE measurement differed dramatically from that in the UPS spectrum, which suggests that the high-n Rydberg (ZEKE) states converging to the D1 vibronic state are short-lived due to electronic autoionization to the D0 continuum. 相似文献
145.
M. Segawa H. Matsue Y. Sekiya S. Yamada T. Shinohara T. Oku H. Sasao J. Suzuki H. M. Shimizu 《Journal of Radioanalytical and Nuclear Chemistry》2008,278(3):647-651
We have constructed a new system which could analyze a position distribution of several elements in a sample with 2 dimensional
prompt γ-ray analysis (2D PGA) system using focused neutron beam at JAEA. We aimed that the system could analyze local information
in a sample with a good signal γ-ray from interested elements to noise of background γ-ray ratio. As a result, this system
could determine the position resolution and spatial resolution within 1 mm. 相似文献
146.
Suzuki K Oku J Izawa K Okabayashi HF Noda I O'Connor CJ 《Journal of colloid and interface science》2008,327(1):21-30
Concentration-resolved 2D correlation gel permeation chromatography (GPC) has been used to examine the intricate details of the HCl-catalyzed polymerization of a polymeric silane-coupling agent (SCA), triethoxysilyl-terminated polystyrene (TESiPS). The concentration-resolved 2D correlation GPC maps directly reflect the marked difference in the aggregate-aggregate interactions of dilute and concentrated monomeric units, which govern the differences in the polymerized products. There is an optimum concentration of SCA for the enhancement of interfacial strength and subsequent polymerization. Thus, the concentration-resolved 2D correlation GPC technique can be used as a powerful tool for elucidation of aggregate-aggregate interactions and reaction mechanisms in a surface- or interface-enhanced reaction system. It has been shown that the yield value of polymerization products can be improved to a marked extent by choosing a high initial monomer concentration, due to the increase in the production of oligomers. Multiple reaction processes are promoted by the self-assembly of the monomeric and oligomeric components. 相似文献
147.
Masaoki Oku Shigeru Suzuki Naofumi Ohtsu Toetsu Shishido Kazuaki Wagatsuma 《Applied Surface Science》2008,254(16):5141-5148
The intrinsic zero-energy loss profiles of transition metal 2p and 3p XPS spectra for Cr, Mn, and Fe oxides are obtained by spectral deconvolution and compared with Shirley-type background corrected profiles. The metal core level spectra are deconvoluted by O 1s spectra as the response function of each oxide. As the O 1s spectra include intrinsic and extrinsic energy loss parts, the background corrected core level spectra are zero-energy loss spectra. The good agreement of the deconvoluted spectra with the reported spectra obtained by the many body effect theory indicates that the background subtraction method is accurate. A comparison of the deconvoluted with the background corrected spectra of the Shirely-type subtraction reveals that almost all the spectra coincide with each other except for Fe 3p with -Fe2O3. The good coincidence of the Shirley-type corrected spectra with the deconvoluted and calculated spectra indicates that Shirley-type background correction can be used for daily quantitative surface analysis. 相似文献
148.
Hiroyuki Oku Jun Fujimoto Takafumi Ohyama Akihiro Hiroki Masaru Yoshida Ryoichi Katakai 《Journal of polymer science. Part A, Polymer chemistry》2000,38(15):2671-2677
Poly(methacryloyl‐L ‐alanine‐methyl ester) (1) has an optically active side chain and consists of thermoshrinking hydrogels upon crosslinking. We synthesized an uncrosslinked polymer of 1 by the γ‐ray polymerization method. For the prepared polymer, variable‐temperature circular dichroism (CD) and 1H NMR spectra were studied, and we found conformational changes in the optically active side chains during the thermally induced phase transition. Intense CD spectra reveal ordered conformation in the side chain of 1 below the phase transition temperature (∼28 °C). A well‐resolved 1H NMR spectrum of 1 at 0 °C shows that the conformational angles in the polymer side chain are fixed at low‐energy minima. With increasing temperature, the frozen side chain starts rotating vigorously and takes an unordered orientation. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2671–2677, 2000 相似文献
149.
Hiroyuki Oku Hitoshi Ohashi Jun Fujimoto Masayuki Shimizu Masaru Yoshida Ryoichi Katakai 《Journal of polymer science. Part A, Polymer chemistry》2000,38(24):4524-4530
Poly(acryloyl‐L ‐proline‐methyl ester) ( 1 ) has optically active side chain, and constitutes thermoresponsive hydrogels upon crosslinking. In this study, we have prepared uncrosslinked polymer of 1 with a 10‐kGy irradiation dose of γ‐ray. For this polymer, 1 , variable temperature circular dichroism (CD) and 1H NMR spectra have been studied in the range of 0–30 °C. The intense CD spectrum at 0 °C suggests that the side chains in 1 have an ordered orientation. The CD intensity decreases gradually with increasing temperature. The decreased intensity of CD spectra indicates that the disordering occurs for the side‐chain orientation. The CD band shape changes discontinuously at 20 °C. In the 1H NMR spectra, signals disappear above 20 °C. These spectral change at 20 °C indicate that the phase transition occurs at around 20 °C from swollen to shrunken phase. Even after the phase transition, the CD spectra are still changing with isochromic point at 212 nm. It appears that the side‐chain conformation is still changing from one state to the other state in the shrunken phase polymers. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4524–4530, 2000 相似文献
150.
Hitoshi Fujimoto Yosuke Oku Tomohiro Ogihara Hirohiko Takuda 《International Journal of Multiphase Flow》2010
The collision of single water droplets with a hot Inconel 625 alloy surface was investigated by a two-directional flash photography technique using two digital still cameras and three flash units. The experiments were conducted under the following conditions: the pre-impact diameters of the droplets ranged from 0.53 to 0.60 mm, the impact velocities ranged from 1.7 m/s to 4.1 m/s, and the solid surface temperatures ranged from 170 °C to 500 °C. When a droplet impacted onto the solid at a temperature of 170 °C, weak boiling was observed at the liquid/solid interface. At temperatures of 200 or 300 °C, numerous vapor bubbles were formed. Numerous secondary droplets then jetted upward from the deforming droplet due to the blowout of the vapor bubbles into the atmosphere. No secondary droplets were observed for a surface temperature of 500 °C at the low-impact Weber numbers (∼30) associated with the impact inertia of the droplets. Experiments using 2.5-mm-diameter droplets were also conducted. The dimensionless collision behaviors of large and small droplets were compared under the same Weber number conditions. At temperatures of less than or equal to 300 °C, the blowout of vapor bubbles occurred at early stages for a large droplet. At a surface temperature of 500 °C, the two dimensionless deformation behaviors of the droplets were very similar to each other. 相似文献