全文获取类型
收费全文 | 87篇 |
免费 | 2篇 |
专业分类
化学 | 46篇 |
晶体学 | 3篇 |
数学 | 5篇 |
物理学 | 35篇 |
出版年
2022年 | 2篇 |
2019年 | 2篇 |
2018年 | 1篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2013年 | 5篇 |
2012年 | 5篇 |
2011年 | 4篇 |
2010年 | 3篇 |
2009年 | 2篇 |
2008年 | 6篇 |
2007年 | 3篇 |
2006年 | 1篇 |
2005年 | 4篇 |
2003年 | 2篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 4篇 |
1999年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1989年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1969年 | 1篇 |
1966年 | 1篇 |
1902年 | 1篇 |
1900年 | 1篇 |
排序方式: 共有89条查询结果,搜索用时 15 毫秒
81.
Golebiowski A Jozwik J Klopfenstein SR Colson AO Grieb AL Russell AF Rastogi VL Diven CF Portlock DE Chen JJ 《Journal of combinatorial chemistry》2002,4(6):584-590
The scope and limitations of the solid-supported synthesis of a bicyclic diketopiperazine, an internal, putative peptide beta-turn mimetic, are presented. The 4CC multicomponent Ugi reaction of alpha-N-Boc-diaminopropionic acid resin ester (an amine input), optically active alpha-bromoacid, aldehyde, and isocyanide is the key step in the proposed synthetic protocol. Application of cyclitive cleavage as the final step led to desired products in high purity. 相似文献
82.
Awasthi AK Boys ML Cain-Janicki KJ Colson PJ Doubleday WW Duran JE Farid PN 《The Journal of organic chemistry》2005,70(14):5387-5397
[reaction: see text] A practical, large-scale synthesis of a beta-amino ester 1 was developed. A chiral imine derived from (S)-phenylglycinol and 3-trimethylsilylpropanal was coupled with the Reformatsky reagent 3 with high diastereoselectivity (de > 98%) to give (SS)-4a as the major isomer. The amino alcohol residue of the coupling product 4 was oxidatively cleaved with sodium periodate in the presence of methylamine. An unusual selective oxidative cleavage of the (SS)-isomer was observed and the imine 6 was obtained with ee > 99% while the (RS)-4b isomer was not cleaved. Reaction with p-toluenesulfonic acid monohydrate allowed for the hydrolysis of the imine and the isolation of the amine as its salt. The title compound 1 was then obtained by transesterification, desilylation, and hydrochloride salt formation in a one-pot process. The method was successfully applied toward the synthesis of a wide variety of beta-amino esters. 相似文献
83.
Bilevel programming: A survey 总被引:15,自引:0,他引:15
Benoít Colson Patrice Marcotte Gilles Savard 《4OR: A Quarterly Journal of Operations Research》2005,3(2):87-107
This paper provides an introductory survey of a class of optimization problems known as bilevel programming. We motivate this class through a simple application, and then proceed with the general formulation of bilevel programs. We consider various cases (linear, linear-quadratic, nonlinear), describe their main properties and give an overview of solution approaches.Received: April 2005, Revised: May 2005, AMS classification:
90C05, 90C11, 90C20, 90C27, 90C3D, 65K05 相似文献
84.
Cazayous M Gallais Y Sacuto A de Sousa R Lebeugle D Colson D 《Physical review letters》2008,101(3):037601
We unravel the magnon spectra of BiFeO3 by means of low-energy inelastic light scattering. We show the existence of two species of magnons corresponding to spin wave excitations in and out of the cycloidal plane. These excitations might be interpreted as electromagnon modes. The present observations present an unique opportunity to study the competition between ferroelectric and magnetic orders. 相似文献
85.
86.
E. U. Weil J. G. Colson P. E. Hoch R. H. Gruber 《Journal of heterocyclic chemistry》1969,6(5):643-649
Upon treatment with alcoholic base, 1,4,5,6,7,7-hexachloro-5-norbornene-endo-cis-2,3-dimethanol (1) yields a tricyclic ether (111) which is converted by sulfuric acid to two epimeric 4,6,7,8,8-pentachloro-octahydro-4,7-methanoisobenzofuran-5-ones (111 A & B). These relatively nontoxic isomers, upon introduction of two chlorine atoms α and α′ to the ether oxygen, yield two epimeric products of high toxicity to insects and mammals. These 1,3,4,6,7,8,8-heptachloro-octahydro-4,7-methanoisobenzofuran-5-ones (IV A & B) upon transannular dehydrochlorination yield a toxic tetracyclic ketone (VI A). Reduction of this ketone by lithium aluminum hydride affords an alcohol (VII) of similarly high insecticidal toxicity. Nuclear magnetic resonance and infrared spectra are presented as evidence for the indicated structures. Results of this study are interpreted as indicative of the regions of the molecule which are critical in regard to toxicity. 相似文献
87.
Time-resolved local induction measurements near the vortex lattice order-disorder transition in optimally doped Bi(2)Sr(2)CaCu(2)O(8+delta) crystals show that the high-field, disordered phase can be quenched to fields as low as half the transition field. Over an important range of fields, the electrodynamical behavior of the vortex system is governed by the coexistence of ordered and disordered vortex phases in the sample. We interpret the results as supercooling of the high-field phase and the possible first-order nature of the order-disorder transition at the "second magnetization peak." 相似文献
88.
Spitler EL Koo BT Novotney JL Colson JW Uribe-Romo FJ Gutierrez GD Clancy P Dichtel WR 《Journal of the American Chemical Society》2011,133(48):19416-19421
Two-dimensional layered covalent organic frameworks (2D COFs) organize π-electron systems into ordered structures ideal for exciton and charge transport and exhibit permanent porosity available for subsequent functionalization. A 2D COF with the largest pores reported to date was synthesized by condensing 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) and 4,4'-diphenylbutadiynebis(boronic acid) (DPB). The COF was prepared as both a high surface area microcrystalline powder as well as a vertically oriented thin film on a transparent single-layer graphene/fused silica substrate. Complementary molecular dynamics and density functional theory calculations provide insight into the interlayer spacing of the COF and suggest that adjacent layers are horizontally offset by 1.7-1.8 ?, in contrast to the eclipsed AA stacking typically proposed for these materials. 相似文献
89.
Anderson AW Marois R Colson ER Peterson BS Duncan CC Ehrenkranz RA Schneider KC Gore JC Ment LR 《Magnetic resonance imaging》2001,19(1):1-5
The objective of this study was to detect auditory cortical activation in non-sedated neonates employing functional magnetic resonance imaging (fMRI). Using echo-planar functional brain imaging, subjects were presented with a frequency-modulated pure tone; the BOLD signal response was mapped in 5 mm-thick slices running parallel to the superior temporal gyrus. Twenty healthy neonates (13 term, 7 preterm) at term and 4 adult control subjects. Blood oxygen level-dependent (BOLD) signal in response to auditory stimulus was detected in all 4 adults and in 14 of the 20 neonates. FMRI studies of adult subjects demonstrated increased signal in the superior temporal regions during auditory stimulation. In contrast, signal decreases were detected during auditory stimulation in 9 of 14 newborns with BOLD response. fMRI can be used to detect brain activation with auditory stimulation in human infants. 相似文献