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31.
《Journal of Coordination Chemistry》2012,65(4):299-305
Two anionic complexes of Au(III) with the bioligand biuret, cis-[Au(Biu)X2]? (BiuH2=biuret, X=Cl, Br), have been synthesized and characterized. The molecular structure of cis-[Au(Biu)Br2]PPh4 has been determined by X-ray diffraction analysis. The complex anion has square-planar geometry with one deprotonated biuret dianion coordinated bidentately to the metal center via the terminal amino nitrogen atoms and two bromide ions in cis positions. There are no significant intermolecular Au-Au interactions in the solid state. Ab initio calculations of the geometric structure at different computational levels for biuret and both anionic complexes as well an IR study of the structures obtained are performed. 相似文献
32.
ZHANG Yong-Fan LIN Wei WANG Qi-Wei LI Yi LI Jun-Qian 《结构化学》2007,26(5):606-612
The reduced SnO2(110) surface has been investigated by using first-principles method with a slab model. By examining the vacancy formation energy of three kinds of reduced SnO2(110) surfaces, the most energetically favorable defect surface is confirmed to be the surface with the coexistence of bridging and in-plane oxygen vacancies, which is different with the traditional model by only removing bridging oxygen. The results of band structure calculations indicate that the electronic structure of this defect surface is similar to the SnO surface. 相似文献
33.
We prove commutative integrability of the Hamilton system on the tangent bundle of the complex projective space whose Hamiltonian coincides with the Hamiltonian of the geodesic flow and the Poisson bracket deforms due to addition of the Fubini–Study form to the standard symplectic form. 相似文献
34.
35.
Richard L. Neitzel Maire S.A. Heikkinen Christopher C. Williams Susan Marie Viet Michael Dellarco 《Applied Acoustics》2016
Knowledge of the auditory and non-auditory effects of noise has increased dramatically over the past decade, but indoor noise exposure measurement methods have not advanced appreciably, despite the introduction of applicable new technologies. This study evaluated various conventional and smart devices for exposure assessment in the National Children’s Study. Three devices were tested: a sound level meter (SLM), a dosimeter, and a smart device with a noise measurement application installed. Instrument performance was evaluated in a series of semi-controlled tests in office environments over 96-h periods, followed by measurements made continuously in two rooms (a child’s bedroom and a most used room) in nine participating homes over a 7-day period with subsequent computation of a range of noise metrics. The SLMs and dosimeters yielded similar A-weighted average noise levels. Levels measured by the smart devices often differed substantially (showing both positive and negative bias, depending on the metric) from those measured via SLM and dosimeter, and demonstrated attenuation in some frequency bands in spectral analysis compared to SLM results. Virtually all measurements exceeded the Environmental Protection Agency’s 45 dBA day–night limit for indoor residential exposures. The measurement protocol developed here can be employed in homes, demonstrates the possibility of measuring long-term noise exposures in homes with technologies beyond traditional SLMs, and highlights potential pitfalls associated with measurements made by smart devices. 相似文献
36.
Dr. Yubo Pang Shuai Chen Dr. Jie Han Prof. Dr. Chengjian Zhu Dr. Chuan-Gang Zhao Prof. Dr. Jin Xie 《Angewandte Chemie (International ed. in English)》2023,62(31):e202306922
Herein, we present a manganese-catalyzed, branched-selective hydroalkenylation of terminal alkynes, under mild conditions through facile installation of a versatile silanol as a removable directing group. With an alkenyl boronic acid as the coupling partner, this reaction produces stereodefined (E,E)-1,3-dienes with high regio-, chemo- and stereoselectivity. The protocol features mild reaction conditions such as room temperature and an air atmosphere, while maintaining excellent functional group compatibility. The resulting 1,3-dienesilanol products serve as versatile building blocks, as the removal of the silanol group allows for the synthesis of both branched terminal 1,3-dienes for downstream coupling reactions, as well as stereoselective construction of linear (E,E)-1,3-dienes and (E,E,E)- or (E,E,Z)-1,3,5-trienes. In addition, a Diels–Alder cycloaddition can smoothly and selectively deliver silicon-containing pentasubstituted cyclohexene derivatives. Mechanistic investigations, in conjunction with DFT calculations, suggest a bimetallic synergistic activation model to account for the observed enhanced catalytic efficiency and good regioselectivity. 相似文献
37.
Stancho Stanchev Frank Jensen Ilia Manolov 《International journal of quantum chemistry》2008,108(8):1340-1351
4‐Hydroxycoumarins are compounds with a lot of applications as drugs and herbicides. They have very interesting spectral and chemical properties, which are investigated theoretically and experimentally. Some new 4‐hydroxycoumarins with arylydene‐β‐ketoester or arylydene‐2,4‐pentanedione side chain were synthesized by two step synthetic scheme. Their structure was characterized by UV–vis, IR, and 1H NMR methods. The spectral behavior of the optimized structures of these compounds was reproduced by the hybrid DFT methods B3LYP and B3P86 with 6‐31G** and aug‐cc‐pVDZ basis sets. Electronic excited states and vibrational frequencies were calculated. HF method was also used for comparison, because of the lack of electronic correlation. The theoretical spectra were compared with the experimental ones. A lot of compounds show good agreement between experimental and some of the theoretical data, especially obtained by aug‐cc‐pVDZ basis set. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008 相似文献
38.
采用密度泛函理论在B3LYP/6-31G**理论水平计算研究含酯基和吡啶环的苯并菲衍生物分子的电荷传输速率.结果表明,酯基双取代的苯并菲衍生物分子具有较高的空穴和电子传输速率,分别为0.22 cm2/v•s和1.51 cm2/v•s.同时引入酯基和吡啶环均不利于空穴和电子传输.使用有限场(FF)方法计算分子的三阶非线性光学性质.结果显示,在酯基和吡啶环之间引入柔性碳链的分子与不含吡啶环分子的三阶非线性光学性质基本一致,均具有较高的电荷传输速率和良好的三阶非线性光学性质. 相似文献
39.
Rajendra K. Sharma Rajnish K. Sharma Audhesh K. Rai Yash Pal Singh 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):1727-1732
The equimolar reactions of Ph 3 Bi with the bifunctional tetradentate Schiff bases proceed with cleavage of two Bi--C bond of Ph 3 Bi and result in the formation of phenylbismuth(III) derivatives PhBi[RC(NC 6 H 4 S)CH 2 (NC 6 H 4 S)CCOOCH 3 ] where R = C 6 H 5 , 4-ClC 6 H 4 ,4-BrC 6 H 4 , and 4-CH 3 C 6 H 4 . Physico-chemical, IR, and NMR ( 1 H and 13 C) spectral studies have been carried out to investigate the structural aspect of these derivatives which reveal a penta coordination around the central Bi atom. 相似文献
40.
《印度化学会志》2021,98(11):100225
The work presented here deals with the fabrication of bare Bi2O3 and modified Bi2O3 photocatalyst. The Bi2O3 material was modified with selected transition metals Co2+, Ni2+ with the 1% and 3% atomic weight percent insitu doping method via co-precipitation strategy. These three catalysts were successfully utilized for the waste water purification via photocatalytic degradation route. These all fabricated materials were precisely characterized by characterization techniques such as XRD, SEM, TEM, BET, IR and UV-DRS. The characterization techniques reveal the successful synthesis of material and effective modification of bismuth oxide lattice. Since, surface area for modified Bi2O3 was found to be enhanced in comparison to the bare Bi2O3, as well as declined band gap energy for modified Bi2O3 clearly indicates the successful doping of Co2+, Ni2+ metals. The bare Bi2O3 and modified Bi2O3 catalyst were employed for photocatalytic degradation of cationic dye R-HCl dye. The modified Bi2O3 found to be excellent over degradation efficiency of R-HCl with almost 97% of dye degradation in comparison to the bare Bi2O3. Reactive oxygen species experiment demonstrate that the addition of isopropyl alcohol (IPA), benzoquinone (BQ) and EDTA found to be successful to quench .OH, O2.- and h+ in photocatalysis mechanism. Additionally, the modified Bi2O3 was employed for phenol molecule degradation to investigate the possible excitation of this molecule under visible light irradiation. 相似文献