全文获取类型
收费全文 | 60篇 |
免费 | 1篇 |
专业分类
化学 | 28篇 |
力学 | 3篇 |
数学 | 1篇 |
物理学 | 29篇 |
出版年
2023年 | 1篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2015年 | 1篇 |
2012年 | 2篇 |
2011年 | 2篇 |
2010年 | 4篇 |
2009年 | 2篇 |
2008年 | 1篇 |
2007年 | 1篇 |
2006年 | 3篇 |
2005年 | 2篇 |
2004年 | 4篇 |
2003年 | 6篇 |
2002年 | 6篇 |
2001年 | 4篇 |
2000年 | 1篇 |
1997年 | 1篇 |
1992年 | 2篇 |
1990年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1980年 | 1篇 |
1974年 | 2篇 |
1932年 | 2篇 |
1927年 | 1篇 |
1925年 | 1篇 |
排序方式: 共有61条查询结果,搜索用时 328 毫秒
1.
Smith AB Doughty VA Sfouggatakis C Bennett CS Koyanagi J Takeuchi M 《Organic letters》2002,4(5):783-786
[reaction: see text] A short, efficient, and stereocontrolled synthesis of (-)-4, an advanced ABCD subunit of the spongistatins, has been achieved. Central to the synthetic strategy is the multicomponent linchpin union of silyl dithianes with epoxides to access both the AB and CD fragments. Fragment coupling was then achieved via an efficient stereoselective aldol reaction. The linear sequence required 22 steps and proceeded in 4.0% overall yield. 相似文献
2.
3.
De Vita R Anghinolfi M Burkert VD Dodge GE Minehart R Taiuti M Weller H Adams G Amaryan MJ Anciant E Armstrong DS Asavapibhop B Asryan G Audit G Auger T Avakian H Bagdasaryan H Ball JP Barrow S Battaglieri M Beard K Bektasoglu M Bianchi N Biselli AS Boiarinov S Bonner BE Bosted P Bouchigny S Branford D Brooks WK Bueltmann S Calarco JR Capitani GP Carman DS Carnahan B Cazes A Ciciani L Cole PL Coleman A Connelly J Cords D Corvisiero P Crabb D Crannell H Cummings JP De Sanctis E Degtyarenko PV 《Physical review letters》2002,88(8):082001
The double spin asymmetry in the (-->)e(-->)p --> e(prime)pi(+)n reaction has been measured for the first time in the resonance region for four-momentum transfer Q2 = 0.35-1.5 GeV(2). Data were taken at Jefferson Lab with the CLAS detector using a 2.6 GeV polarized electron beam incident on a polarized solid NH3 target. Comparison with predictions of phenomenological models shows strong sensitivity to resonance contributions. Helicity-1/2 transitions are found to be dominant in the second and third resonance regions. The measured asymmetry is consistent with a faster rise with Q(2) of the helicity asymmetry A1 for the F(15)(1680) resonance than expected from the analysis of the unpolarized data. 相似文献
4.
Joo K Smith LC Burkert VD Minehart R Aznauryan IG Elouadrhiri L Stepanyan S Adams GS Amaryan MJ Anciant E Anghinolfi M Armstrong DS Asavapibhop B Audit G Auger T Avakian H Barrow S Bagdasaryan H Battaglieri M Beard K Bektasoglu M Bertozzi W Bianchi N Biselli AS Boiarinov S Bonner BE Brooks WK Calarco JR Capitani GP Carman DS Carnahan B Cole PL Coleman A Cords D Corvisiero P Crabb D Crannell H Cummings J De Sanctis E De Vita R Degtyarenko PV Demirchyan RA Denizli H Dennis LC Deppman A 《Physical review letters》2002,88(12):122001
Models of baryon structure predict a small quadrupole deformation of the nucleon due to residual tensor forces between quarks or distortions from the pion cloud. Sensitivity to quark versus pion degrees of freedom occurs through the Q2 dependence of the magnetic (M1+), electric (E1+), and scalar (S1+) multipoles in the gamma*p-->Delta(+)-->p pi(0) transition. We report new experimental values for the ratios E(1+)/M(1+) and S(1+)/M(1+) over the range Q2 = 0.4-1.8 GeV2, extracted from precision p(e,e(')p)pi(0) data using a truncated multipole expansion. Results are best described by recent unitary models in which the pion cloud plays a dominant role. 相似文献
5.
E.W. Duck D. Grant J.R. Horder D.K. Jenkins A.E. Marlow S.R. Wallis A.G. Doughty J.M. Marandon G.A. Skinner 《European Polymer Journal》1974,10(6):481-488
VOCl3-Et3Al2C13(chlorinated activator) catalysts have been employed for the polymerization of ethylene at T between 15 and 85° in n-hexane. Using butylperchlorocrotonate as the activator, the following catalyst efficiencies (g polymerization, hr, atmosphere ethylene in the cap gas) were achieved: 106,1 MFI = 0-00; 105,8, e.g. MFI = 1 0 (with 9 per cent H2 present in the cap gas) and 106–9 MFI = 0?4 (with 44 mmole/1 styrene in the hexane medium). Reactions between the aluminium alkyl and the activator molecules produced other chlorinated species of high average activator effectiveness. The catalyst system could be reactivated by further additions of Et3Al2Cl3. The minimum value of the polymerization propagation rate constant is estimated to be 10122?6x10,461 cm3/mole sec. 相似文献
6.
7.
Simon M. Doughty J.Fraser Stoddart Howard M. Colquhoun Alexandra M.Z. Slawin David J. Williams 《Polyhedron》1985,4(4):567-575
The crystal structure of 2Li picrate.dibenzo-36-crown-12.2H2O was determined by X-ray diffraction methods. The 2:1 (metal:ligand) complex crystalli 相似文献
8.
Rossi P Mirazita M Ronchetti F De Sanctis E Adams G Ambrozewicz P Anciant E Anghinolfi M Asavapibhop B Audit G Avakian H Bagdasaryan H Ball JP Barrow S Battaglieri M Beard K Bektasoglu M Bellis M Benmouna N Berman BL Bertozzi W Bianchi N Biselli AS Boiarinov S Bonner BE Bouchigny S Bradford R Branford D Briscoe WJ Brooks WK Burkert VD Butuceanu C Calarco JR Carman DS Carnahan B Chen S Cole PL Cords D Corvisiero P Crabb D Crannell H Cummings JP De Vita R Degtyarenko PV Denizli H Dennis L 《Physical review letters》2005,94(1):012301
9.
Stavinsky AV Mikhailov KR Lednicky R Vlassov AV Adams G Ambrozewich P Anciant E Anghinolfi M Asavapibhop B Asryan G Audit G Auger T Avakian H Bagdasaryan H Ball JP Barrow S Batourine V Battaglieri M Beard K Bektasoglu M Bellis M Benmouna N Bianchi N Biselli AS Boiarinov S Bonner BE Bouchigny S Bradford R Branford D Brooks WK Burkert VD Butuceanu C Calarco JR Carman DS Cetina C Chen S Cole PL Cords D Coleman A Corvisiero P Crabb D Cummings JP Dashyan N Sanctis ED Vita RD Degtyarenko PV Denizli H 《Physical review letters》2004,93(19):192301
Two-proton correlations at small relative momentum q were studied in the eA(3He,4He,C,Fe)-->e(')ppX reaction at E(0)=4.46 GeV using the CLAS detector at Jefferson Lab. The enhancement of the correlation function at small q was found to be in accordance with theoretical expectations. Sizes of the emission region were extracted, and proved to be dependent on A and on the proton momentum. The size of the two-proton emission region for He was measured in eA reactions for the first time. 相似文献
10.
Battaglieri M Brunoldi M De Vita R Laget JM Osipenko M Ripani M Taiuti M Adams G Amaryan MJ Anciant E Anghinolfi M Armstrong DS Asavapibhop B Asryan G Audit G Auger T Avakian H Barrow S Beard K Bektasoglu M Berman BL Bersani A Bianchi N Biselli AS Boiarinov S Bouchigny S Bradford R Branford D Briscoe WJ Brooks WK Burkert VD Calarco JR Capitani GP Carman DS Carnahan B Cazes A Cetina C Cole PL Coleman A Cords D Corvisiero P Crabb D Crannell H Cummings JP DeSanctis E Degtyarenko PV Demirchyan R 《Physical review letters》2003,90(2):022002
The differential cross section, dsigma/dt, for omega meson exclusive photoproduction on the proton above the resonance region (2.6相似文献