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311.
针对kJ级大能量钕玻璃固体脉冲激光器,对比研究了传统恒温水冷方式和采用加热控制的新型热管理技术下的激光棒温度分布情况。结果表明,采用新型热管理技术可大大降低棒内温度梯度,减小泵浦过程中的热效应,确保大能量激光输出;而且加热循环水的最佳升温值在单泵浦脉冲引起的激光棒平均温升值附近,使得径向温差最小,该最佳升温值与脉冲间隔时间有关,比如脉冲间隔15 s时,循环水在每个脉冲过后的最佳升温值为单泵浦脉冲引起的激光棒平均温升值的0.85倍;采用加热控制后水温和激光棒温度整体升高,因此在工作一个脉冲串后,必须恢复激光棒温度到初始状态,然后再进行下一个脉冲串工作。 相似文献
312.
313.
Öncüoğlu S. Ergün Y. Hızlıateş C. Gündoğdu Akyıldız V. 《Russian Journal of Organic Chemistry》2021,57(8):1330-1335
Russian Journal of Organic Chemistry - The octahydropyridocarbazole skeleton is an important key structure for the synthesis of pyridocarbazole alkaloids, including the antineoplastic agent... 相似文献
314.
W. Parri C. S. Marvel V. du Vigneaud G. Spacu G. A. Barbieri und F. Calzolari 《Fresenius' Journal of Analytical Chemistry》1925,67(1-2):40-41
Ohne Zusammenfassung 相似文献
315.
316.
Ohne ZusammenfassungVorläufige Mitteilung 相似文献
317.
Bartl A. Peiris L.D.H. Bois J.L. du Rixen D.J. Plummer A. 《Experimental Techniques》2020,44(6):837-848
Experimental Techniques - Real-time hybrid testing is a technology which allows the coupling of simulations and component tests in order to simulate complex system dynamics. Delays and time lags... 相似文献
318.
Roxana M. Bîrzoi Dr. Delia Bugnariu Dr. Rafael Guerrero Gimeno Dr. Daniela Lungu Vera Zota Dr. Constantin Daniliuc Dr. Peter G. Jones Prof. Dr. Zoltán Benkõ Dr. László Könczöl László Nyulászi Prof. Dr. Rainer Bartsch Dr. Wolf‐W. du Mont Prof. Dr. Edgar Niecke Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(16):4843-4851
Deprotonation of aminophosphaalkenes (RMe2Si)2C?PN(H)(R′) (R=Me, iPr; R′=tBu, 1‐adamantyl (1‐Ada), 2,4,6‐tBu3C6H2 (Mes*)) followed by reactions of the corresponding Li salts Li[(RMe2Si)2C?P(M)(R′)] with one equivalent of the corresponding P‐chlorophosphaalkenes (RMe2Si)2C?PCl provides bisphosphaalkenes (2,4‐diphospha‐3‐azapentadienes) [(RMe2Si)2C?P]2NR′. The thermally unstable tert‐butyliminobisphosphaalkene [(Me3Si)2C?P]2NtBu ( 4 a ) undergoes isomerisation reactions by Me3Si‐group migration that lead to mixtures of four‐membered heterocyles, but in the presence of an excess amount of (Me3Si)2C?PCl, 4 a furnishes an azatriphosphabicyclohexene C3(SiMe3)5P3NtBu ( 5 ) that gave red single crystals. Compound 5 contains a diphosphirane ring condensed with an azatriphospholene system that exhibits an endocylic P?C double bond and an exocyclic ylidic P(+)? C(?)(SiMe3)2 unit. Using the bulkier iPrMe2Si substituents at three‐coordinated carbon leads to slightly enhanced thermal stability of 2,4‐diphospha‐3‐azapentadienes [(iPrMe2Si)2C?P]2NR′ (R′=tBu: 4 b ; R′=1‐Ada: 8 ). According to a low‐temperature crystal‐structure determination, 8 adopts a non‐planar structure with two distinctly differently oriented P?C sites, but 31P NMR spectra in solution exhibit singlet signals. 31P NMR spectra also reveal that bulky Mes* groups (Mes*=2,4,6‐tBu3C6H2) at the central imino function lead to mixtures of symmetric and unsymmetric rotamers, thus implying hindered rotation around the P? N bonds in persistent compounds [(RMe2Si)2C?P]2NMes* ( 11 a , 11 b ). DFT calculations for the parent molecule [(H3Si)2C?P]2NCH3 suggest that the non‐planar distortion of compound 8 will have steric grounds. 相似文献
319.
Alisa Rudnitskaya Hélène H. Nieuwoudt Nina Muller Andrey Legin Maret du Toit Florian F. Bauer 《Analytical and bioanalytical chemistry》2010,397(7):3051-3060
An electronic tongue (ET) based on potentiometric chemical sensors was assessed as a rapid tool for the quantification of
bitterness in red wines. A set of 39 single cultivar Pinotage wines comprising 13 samples with medium to high bitterness was
obtained from the producers in West Cape, South Africa. Samples were analysed with respect to a set of routine wine parameters
and major phenolic compounds using Fourier transform infrared-multiple internal reflection spectroscopy (WineScan) and high-performance
liquid chromatography, respectively. A trained sensory panel assessed the bitterness intensity of 15 wines, 13 of which had
a bitter taste of medium to high intensity. Thirty-one wine samples including seven bitter-tasting ones were measured by the
ET. Influence of the chemical composition of wine on the occurrence of the bitter taste was evaluated using one-way analysis
of variance. It was found that bitter-tasting wines had higher concentrations of phenolic compounds (catechin, epicatechin,
gallic and caffeic acids and quercetin) than non-bitter wines. Sensitivity of the sensors of the array to the phenolic compounds
related to the bitterness was studied at different pH levels. Sensors displayed sensitivity to all studied compounds at pH 7,
but only to quercetin at pH 3.5. Based on these findings, the pH of wine was adjusted to 7 prior to measurements. Calibration
models for classification of wine samples according to the presence of the bitter taste and quantification of the bitterness
intensity were calculated by partial least squares-discriminant analysis (PLS-DA) regression. Statistical significance of
the classification results was confirmed by the permutation test. Both ET and chemical analysis data could discriminate between
bitter and control wines with the correct classification rates of 94% and 91%, respectively. Prediction of the bitterness
intensity with good accuracy (root mean square error of 2 and mean relative error of 6% in validation) was possible only using
ET data. 相似文献
320.
C. R. Stia M.-P. Gaigeot R. Vuilleumier O. A. Fojón M.-A. Hervé du Penhoat M.-F. Politis 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,60(1):77-83
We present a series of ab initio density functional based
calculations of the fragmentation dynamics of core-ionized
biomolecules. The computations are performed for pure liquid water,
aqueous and isolated Uracil. Core ionization is
described by replacing the 1s
2 pseudopotential of one atom of the target
molecule (C, N or O) with a pseudopotential for a 1s
1 core-hole state.
Our results predict that the dissociation of core-ionized water
molecules may be reached during the lifetime of inner-shell vacancy
(less than 10 fs), leading to OH bond breakage as a primary outcome.
We also observe a second fragmentation channel in which total Coulomb explosion
of the ionized water molecule occurs. Fragmentation pathways are found
similar for pure water or when the water molecule is in the primary hydration
shell of the uracil molecule. In the latter case, the proton may be transferred
towards the uracil oxygen atoms. When the core hole is located on the uracil
molecule, ultrafast dissociation is only observed in the aqueous environment
and for nitrogen-K vacancies, resulting in proton transfers towards
the hydrogen-bonded water molecule. 相似文献