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391.
Fusano A Sumino S Nishitani S Inouye T Morimoto K Fukuyama T Ryu I 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(30):9415-9422
The atom-transfer carbonylation reaction of various alkyl iodides thereby leading to carboxylic acid esters was effectively accelerated by the addition of transition-metal catalysts under photoirradiation conditions. By using a combined Pd/hν reaction system, vicinal C-functionalization of alkenes was attained in which α-substituted iodoalkanes, alkenes, carbon monoxide, and alcohols were coupled to give functionalized esters. When alkenyl alcohols were used as acceptor alkenes, three-component coupling reactions, which were accompanied by intramolecular esterification, proceeded to give lactones. Pd-dimer complex [Pd(2)(CNMe)(6)][PF(6)](2), which is known to undergo homolysis under photoirradiation conditions, worked quite well as a catalyst in these three- or four-component coupling reactions. In this metal/radical hybrid system, both Pd radicals and acyl radicals are key players and a stereochemical study confirmed the carbonylation step proceeded through a radical carbonylation mechanism. 相似文献
392.
Baba M Mori K Yamawaki M Akita K Ito M Kasahara S Yamanaka T 《The journal of physical chemistry. A》2006,110(33):10000-10005
Fluorescence excitation spectra of dibenzofuran in a supersonic jet are observed and the vibronic structure is analyzed for the S(1) (1)A(1) (pipi) and S(0) states. An observation of the rotational envelopes reveals that the band is a B-type band. However, it is shown that most of the strong vibronic bands are A-type bands. The intensity arises from vibronic coupling with the S(2) (1)B(2) state. We find a broad emission in the dispersed fluorescence spectrum for the excitation of the high vibrational levels in the S(1) state. This indicates that intramolecular vibrational redistribution (IVR) occurs efficiently in the isolated dibenzofuran molecule. 相似文献
393.
Takaya T Saha S Hamaguchi HO Sarkar M Samanta A Iwata K 《The journal of physical chemistry. A》2006,110(13):4291-4295
We study the effects of symmetry breaking on the photogenerated intramolecular charge transfer (CT) state of 9,9'-bianthryl (BA) with femtosecond time-resolved near-IR spectroscopy. The time-resolved near-IR spectra are measured in acetonitrile for a symmetric substituted derivative of 10,10'-dicyano-9,9'-bianthryl (DCBA) and asymmetric substituted derivatives of 10-cyano-9,9'-bianthryl (CBA) and 9-(N-carbazolyl)anthracene (C9A), as well as nonsubstituted BA. The transient near-IR absorption spectrum of each compound at 0 ps has a locally excited (LE) absorption band, which agrees with the transient absorption band of the corresponding monomer unit. At 3 ps after the photoexcitation, the symmetric compounds show a broad charge transfer (CT) absorption band, whereas no absorption peak appears in the spectra of the asymmetric compounds. The broad CT absorption at 1250 nm only observed for the symmetric compounds can be attributed to the charge resonance transition associated with two equivalent charge separated states. 相似文献
394.
[STRUCTURE: SEE TEXT] Intermolecular 1,5-dipolar cycloaddition reaction of tungsten-containing vinylazomethine ylide, generated from o-(alk-3-en-1-ynyl)phenylbenzaldimines and tungsten carbonyl complex, with ketene acetals proceeds efficiently to give azepino[1,2-a]indole derivatives in good yield. Formation of [5+2] or [3+2] cycloadducts can be controlled by an appropriate choice of dipolarophile. 相似文献
395.
When the esters of arylboronic acids with 2,2-dimethylpropan-1,3-diol were treated with a catalytic amount of [Rh(OH)(cod)]2 in the presence of 1,3-bis(diphenylphosphino)propane and CsF in dioxane at 60 degrees C under carbon dioxide atmosphere, the benzoic acid derivatives were obtained in good yields. Reactions of alkenylboronic esters also proceeded under similar conditions to give alpha,beta-unsaturated carboxylic acids. As these boronic esters are now easily available through coupling or direct borylation reactions, this method would be a useful method for the preparation of various functionalized aryl- and alkenyl-carboxylic acids. 相似文献
396.
Ryo Masuda Takaya Mitsui Keiji Itoh Kouji Sakaki Hirotoshi Enoki Yumiko Nakamura Makoto Seto 《Hyperfine Interactions》2012,204(1-3):139-142
We have been developing a system for in situ M?ssbauer studies using synchrotron radiation (SR) to elucidate the mechanism of hydrogenation processes. In the system, samples reacts in a pressure-temperature chamber and SR-based M?ssbauer spectra using variable-frequency nuclear monochromator and energy spectra of inelastic nuclear resonant scattering (NRS) of SR are measured. As a feasibility study, the temperature dependence of the M?ssbauer and inelastic NRS spectra of 57Fe in c-GdFe2H3 under vacuum were measured. In both spectra, clear differences were observed between 373?K and 573?K. These differences can be interpreted by the change of microscopic environment around Fe at the dehydrogenation. Thus, it is confirmed that this system works well enough to perform the in-situ M?ssbauer study on the dehydrogenation of c-GdFe2H3. 相似文献
397.
Akira Yoshiasa Genta Yagyu Tomokazu Ito Takamitu Yamanaka Takaya Nagai 《无机化学与普通化学杂志》2000,626(1):36-41
Crystal structures of the ambient pressure and temperature phase (phase I) and high pressure phase (phase II) in CuGeO3 were studied by means of the high pressure single‐crystal X‐ray diffraction method in a diamond anvil cell using high power X‐ray generator and imaging plate detector. The pressure dependence of the atomic displacements in the phase I was investigated under the hydrostatic pressure of 0.1 MPa and 2.9 and 3.9 GPa. The lattice is particularly compressive in the b direction. In phase I the rippled layers are formed by the corner‐shared chains of GeO4 tetrahedra and edge‐linked planar CuO4. Major effects of pressure, directly related to the shortening of the b‐axis, consist of an enhanced folding of the rippled layers towards the b‐direction and of a shortening of the weak Cu–O bond. The crystal structure of phase II is monoclinic, a = 4.935(57), b = 6.754(14), c = 6.208(11) Å, β = 92.67(3)°, space group; P21/c. The transition from phase I to II involves a corrugated arrangement of the both cation with some oxygens around the c‐axis. Ge ion at the transition point of 6.4 GPa changes its coordination number from four‐fold to five‐fold, and Cu ion occupies a position of seven‐fold site. The structure of phase II is explained as a slab structure having unique edge‐ and corner‐sharing arrangements of GeO5 and CuO7 polyhedra. The average Ge–O and Cu–O distances in phase II is 1.92 and 2.17 Å, respectively, at 6.5 GPa. 相似文献
398.
Yoshitaka Yamaguchi Noriyuki Suzuki Arno Fries Takaya Mise Hiroyuki Koshino Yuji Ikegami Hiromichi Ohmori Akira Matsumoto 《Journal of polymer science. Part A, Polymer chemistry》1999,37(3):283-292
Stereospecific polymerization of 1‐hexene under high pressures (up to 1,000 MPa = ca. 10,000 atm) using metallocene/methylaluminoxane (MAO) catalysts was investigated. Several C2‐symmetric ansa‐metallocenes, their meso‐isomers, and two Cs‐symmetric ansa‐metallocenes were employed as catalyst precursors. In the course of this study, novel C2‐symmetric germylene‐bridged ansa‐metallocenes, (rac‐[Me2Ge(η5‐C5H‐2,3,5‐Me3)2MCl2] (M = Zr, rac‐4a; M = Hf, rac‐4b), have been prepared. High pressures induced enhancement of the catalytic activity and the molecular weight of the polymers in most of the catalysts. The maximum of both the catalytic activity and the molecular weight of the polymers was mostly observed at 100–500 MPa in each catalyst, although the enhanced ratio was smaller than that observed for nonbridged metallocenes. Isospecificity of the C2‐symmetric ansa‐metallocene catalysts was essentially maintained even under high pressure. Highly isotactic polyhexene ([mmmm] = 91.6%) with very high molecular weight (Mw = 2,360,000) was achieved by rac‐4b under 250 MPa. High pressures slightly decreased syndiotacticity when the Cs‐symmetric ansa‐metallocene, isopropylidene(1‐η5‐cyclopentadienyl)(9‐η5‐fluorenyl)zirconium dichloride 5, was employed. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 283–292, 1999 相似文献
399.
Gadge Sandhya Tamboli Ashif Shinde Manish Fouad Hassan Terashima Chiaki Chauhan Ratna Gosavi Suresh 《Journal of Solid State Electrochemistry》2023,27(8):2005-2015
Journal of Solid State Electrochemistry - The industrial revolution has raised major concern of environmental pollution, due to excess release of hazardous chemical, dyes, etc. into water bodies.... 相似文献
400.