全文获取类型
收费全文 | 384篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
化学 | 270篇 |
晶体学 | 3篇 |
力学 | 5篇 |
数学 | 17篇 |
物理学 | 92篇 |
出版年
2023年 | 3篇 |
2021年 | 4篇 |
2020年 | 7篇 |
2017年 | 3篇 |
2015年 | 3篇 |
2014年 | 3篇 |
2013年 | 18篇 |
2012年 | 13篇 |
2011年 | 17篇 |
2010年 | 13篇 |
2009年 | 5篇 |
2008年 | 17篇 |
2007年 | 20篇 |
2006年 | 19篇 |
2005年 | 17篇 |
2004年 | 13篇 |
2003年 | 12篇 |
2002年 | 13篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 10篇 |
1998年 | 3篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 10篇 |
1993年 | 7篇 |
1992年 | 5篇 |
1991年 | 8篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 8篇 |
1979年 | 8篇 |
1978年 | 13篇 |
1977年 | 9篇 |
1975年 | 9篇 |
1974年 | 5篇 |
1973年 | 5篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1969年 | 4篇 |
1966年 | 2篇 |
1965年 | 3篇 |
1963年 | 2篇 |
排序方式: 共有387条查询结果,搜索用时 0 毫秒
61.
Banerji B Conejo-Garcia A McNeill LA McDonough MA Buck MR Hewitson KS Oldham NJ Schofield CJ 《Chemical communications (Cambridge, England)》2005,(43):5438-5440
Cyclic beta-oxocarboxylic acids inhibit factor inhibiting hypoxia-inducible factor via ligation to the active site iron. 相似文献
62.
63.
H. C. Beachell Jean C. Peterson Buck 《Journal of polymer science. Part A, Polymer chemistry》1969,7(7):1873-1879
A high molecular weight linear polyurethane was prepared by the polyaddition of equimolar amounts of ethylene glycol and methylene bis(4-phenyl isocyanate). Varying amounts of the labile carbamate protons of the polyurethane backbone were substituted by a number of groups of varying length and composition. The resultant grafted or nitrogen-substituted polyurethanes were then studied viscometrically in both polymer solvent and in a polymer solvent—nonsolvent mixture. The configuration of the nitrogen-substituted polyurethane was found to be dependent upon the number and length of pendent branches. 相似文献
64.
Marianne E. Van Dommelen Jan W. De Haan Henk M. Buck 《Magnetic resonance in chemistry : MRC》1980,14(6):497-501
The usefulness and some of the limitations of the linear electric field (LEF) effect in 13C NMR are illustrated by means of model calculations on the 13C NMR chemical shifts of C-1 and C-2 in 5-chloro-1-pentene in nine different conformations. Two different concepts are used in order to calculate the electric fields near C-1 and C-2 caused by the C-5? Cl dipole. It is also demonstrated that, when using charges calculated by CNDO/2, the influences of the hydrogen atoms at C-5 cannot be neglected. The use of the dipole–dipole interaction formula is advocated. The consequences of taking into account the additional contributions of the vinylic bonds to the accumulated charges at C-1 and C-2 are described. The results with the dipole–dipole formula show that the same signs and similar magnitudes of the LEF effects are calculated in seven out of nine conformations of 5-chloro-1-pentene. This reduces the LEF to a means of confirming, rather than deducing, conformational equilibria in acylic flexible compounds. The usefulness of some recently published applications of the LEF concept to explain some short range substituent effects is critically discussed, mainly in view of the inhomogeneities of the calculated electric fields. 相似文献
65.
[reaction: see text] The absolute configuration of methyl lactobacillate and its 9,10 homologue, both isolated from Escherichia coli B-ATCC 11303, was found to be 11R,12S and 9R,10S, respectively. 相似文献
66.
Matthew Buck 《Results in Mathematics》2013,63(3-4):805-815
We substantially strengthen an unpublished result of Whitehead from his PhD thesis (Whitehead, A.: Differential equations and differential polynomials in the complex. PhD thesis, University of Nottingham, 2002) using a refinement of his techniques. 相似文献
67.
Cwiklik L Buck U Kulig W Kubisiak P Jungwirth P 《The Journal of chemical physics》2008,128(15):154306
Ab initio molecular dynamics simulations modeling low-energy collisions of a sodium atom with a cluster with more than 30 water molecules are presented. We follow the dynamics of the atom-cluster interaction and the delocalization of the valence electron of sodium together with the changes in the electron binding energy. This electron tends to be shared by the nascent sodium cation and the water cluster. IR spectra of the sodium-water cluster are both computationally and experimentally obtained, with a good agreement between the two approaches. 相似文献
68.
Steven M. Maley Graham R. Lief Richard M. Buck Orson L. Sydora Qing Yang Steven M. Bischof Daniel H. Ess 《Journal of computational chemistry》2023,44(4):506-515
Quantum-mechanical-based computational design of molecular catalysts requires accurate and fast electronic structure calculations to determine and predict properties of transition-metal complexes. For Zr-based molecular complexes related to polyethylene catalysis, previous evaluation of density functional theory (DFT) and wavefunction methods only examined oxides and halides or select reaction barrier heights. In this work, we evaluate the performance of DFT against experimental redox potentials and bond dissociation enthalpies (BDEs) for zirconocene complexes directly relevant to ethylene polymerization catalysis. We also examined the ability of DFT to compute the fourth atomic ionization potential of zirconium and the effect the basis set selection has on the ionization potential computed with CCSD(T). Generally, the atomic ionization potential and redox potentials are very well reproduced by DFT, but we discovered relatively large deviations of DFT-calculated BDEs compared to experiment. However, evaluation of BDEs with CCSD(T) suggests that experimental values should be revisited, and our CCSD(T) values should be taken as most accurate. 相似文献
69.
Oncák M Slavícek P Poterya V Fárník M Buck U 《The journal of physical chemistry. A》2008,112(24):5344-5353
Extensive ab initio calculations complemented by a photodissociation experiment at 193 nm elucidate the nature of hydrogen halide molecules bound on free ice nanoparticles. Electronic absorption spectra of small water clusters (up to 5 water molecules) and water clusters doped with hydrogen fluoride, hydrogen chloride and hydrogen bromide were calculated. The spectra were modeled at the time-dependent density functional (TDDFT) level of theory with the BHandHLYP functional using the reflection principle. We observe the emergence of a charge-transfer-to-solvent (CTTS) band in the absorption spectra upon the acidic dissociation of the hydrogen halides. The CTTS band provides a spectroscopically observable feature for the acidic dissociation. The calculated spectra were compared with our new experimental photodissociation data for larger water clusters doped with HCl and HBr. We conclude that HCl and HBr dissociate to a large extent on the surface of ice nanoparticles at temperatures near 120 K and photoactive products are formed. The acidic dissociation of HX leads to an enhancement by about 4 orders of magnitude of the HCl photolysis rate in the 200-300 nm region, which is potentially relevant for the halogen budget in the atmosphere. 相似文献
70.
Liu W Buck M Chen N Shang M Taylor NJ Asoud J Wu X Hasinoff BB Dmitrienko GI 《Organic letters》2007,9(15):2915-2918
The structurally novel diazobenzo[a]fluorene antibiotic isoprekinamycin (IPK) has been synthesized for the first time employing a Suzuki coupling of a brominated AB ring synthon with a boronate ester representing the D ring, followed by anionic cyclization and appropriate functional group manipulations. The first indication that the diazobenzo[a]fluorene system exhibits in vitro anticancer activity is provided and X-ray crystallographic evidence for enhancement of diazonium ion character as a consequence of intramolecular H-bonding is described. 相似文献