全文获取类型
收费全文 | 2049篇 |
免费 | 2篇 |
国内免费 | 11篇 |
专业分类
化学 | 1410篇 |
晶体学 | 12篇 |
力学 | 29篇 |
数学 | 340篇 |
物理学 | 271篇 |
出版年
2022年 | 8篇 |
2021年 | 9篇 |
2020年 | 14篇 |
2018年 | 13篇 |
2017年 | 9篇 |
2016年 | 13篇 |
2015年 | 12篇 |
2014年 | 21篇 |
2013年 | 107篇 |
2012年 | 84篇 |
2011年 | 99篇 |
2010年 | 72篇 |
2009年 | 42篇 |
2008年 | 104篇 |
2007年 | 108篇 |
2006年 | 128篇 |
2005年 | 132篇 |
2004年 | 113篇 |
2003年 | 96篇 |
2002年 | 81篇 |
2001年 | 18篇 |
2000年 | 20篇 |
1999年 | 23篇 |
1998年 | 21篇 |
1997年 | 32篇 |
1996年 | 35篇 |
1995年 | 17篇 |
1994年 | 37篇 |
1993年 | 33篇 |
1992年 | 16篇 |
1991年 | 24篇 |
1990年 | 23篇 |
1989年 | 20篇 |
1988年 | 21篇 |
1987年 | 18篇 |
1986年 | 16篇 |
1985年 | 31篇 |
1984年 | 31篇 |
1983年 | 15篇 |
1982年 | 52篇 |
1981年 | 41篇 |
1980年 | 36篇 |
1979年 | 34篇 |
1978年 | 30篇 |
1977年 | 36篇 |
1976年 | 25篇 |
1975年 | 18篇 |
1974年 | 20篇 |
1973年 | 13篇 |
1971年 | 8篇 |
排序方式: 共有2062条查询结果,搜索用时 31 毫秒
991.
John M. Warman Wouter Schuddeboom Stephan A. Jonker Matthijs P. de Haas Michael N. Paddon-Row Klaas A. Zachariasse Jean-Pierre Launay 《Chemical physics letters》1993,210(4-6):397-404
Transient changes in the real and imaginary component of the complex permittivity of a flash-photolyzed solution can be monitored with nanosecond time resolution using the time-resolved microwave conductivity (TRMC) technique. Effects caused by rapid (picosecond), flip—flop switching between dipolar resonance structures in the S1 and T1 states of molecules with mirror symmetry have been observed. 相似文献
992.
The extension to 15N NMR of the model by linear difference previously proposed for (α-Me.) 13C shifts gathers in an unifying treatment the different behaviours observed for (α-Me.) shifts in 15M and 13C of, aliphatic amines, hydrochlorides and alkanes. 相似文献
993.
Chass GA Mirasol RS Setiadi DH Tang TH Chin W Mons M Dimicoli I Dognon JP Viskolcz B Lovas S Penke B Csizmadia IG 《The journal of physical chemistry. A》2005,109(24):5289-5302
Computational and experimental determinations were carried out in parallel on the conformational probability of N-Acetyl-Phenylalanine-NH2 (NAPA). Ab initio computations were completed at the BLYP/6-311G(df,p), B3LYP/6-31G(d), B3LYP/6-31G(d,p), and B3LYP/6-31+G(d) levels of theory, labeled L/61fp, B/6, B/6p, and B/6+, respectively. Three experimentally identified conformers were compared with theoretical data, confirming their identities as the betaLanti, gammaLgauche+, and gammaLgauche- (BACKBONESIDECHAIN) conformers. Evidence comes from matching experimental and theoretical data for all three constituent N-H stretches of NAPA, with a Delta(Experimental-Theoretical) = approximately 1-3 cm(-1), approximately 0-5 cm(-1), and approximately 1-6 cm(-1), at the L/61fp and B/6+ levels, respectively. Corrected-ZPE relative energies were computed to be 0.14, 0.00, 0.26 and 0.00, 0.67, 0.57 (kcal*mol(-1)) for the betaLanti, gammaLgauche+, and gamma(Lgauche- conformers, respectively, at the L/61fp and B/6+ levels, respectively. The MP2/6-31+G(d) level of theory was subsequently found to give similar relative energies. Characterization of the intramolecular interactions responsible for red and blue shifting of the N-H stretches showed the existence of the following intramolecular interactions: C=O[i]- - -HN[i], (Ar[i])-Cgamma- - -HN[i+1], (Ar[i])-Cdelta-H- - -O=C[i-1] for betaLanti; C=O[i-1]- - -HN[i+1], (Ar[i])-Cgamma- - -HN[i+1], (Ar[i])-C-H- - -O=C[i] for gammaLgauche+; and C=O[i-1]- - -HN[i+1] for gammaLgauche-. Each of these interactions were further investigated and subsequently characterized by orbital population and Atoms-In-Molecules (AIM) analyses, with the identity of overlap and bond critical points (BCP) serving as 'scoring criteria', respectively. Experimental and theoretical carbonyl stretches were also compared and showed good agreement, adding further strength to the synergy between experiment and theory. 相似文献
994.
995.
Christophe Henry K. Karin Norrfors Michał Olejnik Muriel Bouby Johannes Luetzenkirchen Susanna Wold Jean-Pierre Minier 《Adsorption》2016,22(4-6):503-515
This study is focussed on the simulation of particle agglomeration at relatively high ionic strength using a refined stochastic algorithm developed in the context of parcel-tracking approaches. For that purpose, experimental data of both diffusion-limited and reaction-limited aggregation of latex particles were obtained using dynamic light scattering techniques for different initial particle sizes (diameters ranging from 24 to 495 nm) and at various chemical conditions (ionic strength between 0.5 and 2 M with NaCl or CaCl\(_2\) solutions). The experimental data collected have been compared to numerical results obtained with the refined parcel-tracking algorithm for particle agglomeration which has been developed. Results show that the evolution of the aggregate diameters over time can be properly captured by the present model with the value of the aggregate fractal dimension that is extracted from experimental data. 相似文献
996.
Prof. Zhengxing Qin Zhenchao You Dr. Krassimir N. Bozhilov Prof. Stefan K. Kolev Wei Yang Dr. Yanfeng Shen Prof. Xin Jin Dr. Jean-Pierre Gilson Prof. Svetlana Mintova Prof. Georgi N. Vayssilov Prof. Valentin Valtchev 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(16):e202104339
The mesopores formation in zeolite crystals has long been considered to occur through the stochastic hydrolysis and removal of framework atoms. Here, we investigate the NH4F etching of representative small, medium, and large pore zeolites and show that the zeolite dissolution behavior, therefore the mesopore formation probability, is dominated by zeolite architecture at both nano- and sub-nano scales. At the nano-scale, the hidden mosaics of zeolite structure predetermine the spatio-temporal dissolution of the framework, hence the size, shape, location, and orientation of the mesopores. At the sub-nano scale, the intrinsic micropore size and connectivity jointly determine the diffusivity of reactant and dissolved products. As a result, the dissolution propensity varies from removing small framework fragments to consuming nanodomains and up to full digestion of the outmost part of zeolite crystals. The new knowledge will lead to new understanding of zeolite dissolution behavior and new adapted strategies for tailoring hierarchical zeolites. 相似文献
997.
998.
Jean-Pierre Magnot 《International Journal of Theoretical Physics》2018,57(7):2093-2102
We propose here a new discretization method for a class of continuum gauge theories which action functionals are polynomials of the curvature. Based on the notion of holonomy, this discretization procedure appears gauge-invariant for discretized analogs of Yang-Mills theories, and hence gauge-fixing is fully rigorous for these discretized action functionals. Heuristic parts are forwarded to the quantization procedure via Feynman integrals and the meaning of the heuristic infinite dimensional Lebesgue integral is questioned. 相似文献
999.
Dr. Marin Puget Viacheslav Shcherbakov Dr. Sergey Denisov Prof. Philippe Moreau Dr. Jean-Pierre Dognon Prof. Mehran Mostafavi Dr. Sophie Le Caër 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(31):8185-8194
Numerous additives are used in the electrolytes of lithium-ion batteries, especially for the formation of an efficient solid electrolyte interphase at the surface of the electrodes. Understanding the degradation processes of these compounds is thus important; they can be seen through radiolysis. In the case of fluoroethylene carbonate (FEC), picosecond pulse radiolysis experiments evidenced the formation of FEC.−. This radical is stabilized in neat FEC, whereas the ring opens to form more stable radical anions when FEC is a solute in other solvents, as confirmed by quantum chemistry calculations. In neat FEC, pre-solvated electrons primarily undergo attachment rather than solvation. On long timescales, the gases produced (H2, CO, and CO2) were quantified. A reaction scheme for both the oxidizing and reducing pathways at stake in irradiated FEC is proposed. This work shows that the nature of the primary species formed in FEC depends on the amount of FEC in the solution. 相似文献