全文获取类型
收费全文 | 333篇 |
免费 | 9篇 |
国内免费 | 3篇 |
专业分类
化学 | 177篇 |
晶体学 | 1篇 |
力学 | 3篇 |
数学 | 32篇 |
物理学 | 132篇 |
出版年
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 2篇 |
2019年 | 8篇 |
2018年 | 10篇 |
2016年 | 8篇 |
2015年 | 5篇 |
2014年 | 6篇 |
2013年 | 18篇 |
2012年 | 12篇 |
2011年 | 25篇 |
2010年 | 11篇 |
2009年 | 9篇 |
2008年 | 23篇 |
2007年 | 20篇 |
2006年 | 29篇 |
2005年 | 25篇 |
2004年 | 11篇 |
2003年 | 7篇 |
2002年 | 6篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 6篇 |
1984年 | 2篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1979年 | 9篇 |
1978年 | 7篇 |
1977年 | 4篇 |
1976年 | 2篇 |
1975年 | 5篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1970年 | 2篇 |
1968年 | 2篇 |
1967年 | 1篇 |
1942年 | 2篇 |
1935年 | 2篇 |
排序方式: 共有345条查询结果,搜索用时 109 毫秒
341.
Athar SB Patel R Yelton J Rubin P Eisenstein BI Karliner I Mehrabyan S Lowrey N Selen M White EJ Wiss J Mitchell RE Shepherd MR Besson D Pedlar TK Cronin-Hennessy D Gao KY Hietala J Kubota Y Klein T Lang BW Poling R Scott AW Zweber P Dobbs S Metreveli Z Seth KK Tomaradze A Libby J Powell A Wilkinson G Ecklund KM Love W Savinov V Lopez A Mendez H Ramirez J Ge JY Miller DH Shipsey IP Xin B Adams GS Anderson M Cummings JP Danko I Hu D Moziak B Napolitano J He Q Insler J Muramatsu H Park CS 《Physical review letters》2008,100(18):181802
Using e+e--->Ds*-Ds+ data collected near the peak Ds production energy, Ecm=4170 MeV, with the CLEO-c detector, we present the first observation of the decay Ds+-->pn. We measure a branching fraction B(Ds+-->pn)=(1.30+/-0.36(-0.16)+0.12)x10(-3). This is the first observation of a charmed meson decaying into a baryon-antibaryon final state. 相似文献
342.
Cronin-Hennessy D Gao KY Gong DT Hietala J Kubota Y Klein T Lang BW Poling R Scott AW Smith A Zweber P Dobbs S Metreveli Z Seth KK Tomaradze A Ernst J Severini H Dytman SA Love W Savinov V Aquines O Li Z Lopez A Mehrabyan S Mendez H Ramirez J Huang GS Miller DH Pavlunin V Sanghi B Shipsey IP Xin B Adams GS Anderson M Cummings JP Danko I Napolitano J He Q Insler J Muramatsu H Park CS Thorndike EH Yang F Coan TE Gao YS Liu F Artuso M Blusk S Butt J Li J Menaa N Mountain R Nisar S 《Physical review letters》2008,100(25):251802
By using 1.8x10{6} DDpairs, we have measured B(D{0}-->pi{-}e{+}nu{e})=0.299(11)(9)%, B(D{+}-->pi{0}e{+}nu{e})=0.373(22)(13)%, B(D{0}-->K{-}e{+}nu{e})=3.56(3)(9)%, and B(D{+}-->K{0}e{+}nu{e})=8.53(13)(23)% and have studied the q;{2} dependence of the form factors. By combining our results with recent lattice calculations, we obtain |V{cd}|=0.217(9)(4)(23) and |V{cs}|=1.015(10)(11)(106). 相似文献
343.
Dobbs S Metreveli Z Seth KK Tomaradze A Libby J Powell A Wilkinson G Ecklund KM Love W Savinov V Lopez A Mendez H Ramirez J Ge JY Miller DH Shipsey IP Xin B Adams GS Anderson M Cummings JP Danko I Hu D Moziak B Napolitano J He Q Insler J Muramatsu H Park CS Thorndike EH Yang F Artuso M Blusk S Khalil S Li J Mountain R Nisar S Randrianarivony K Sultana N Skwarnicki T Stone S Wang JC Zhang LM Bonvicini G Cinabro D Dubrovin M Lincoln A Naik P Rademacker J Asner DM Edwards KW Reed J Briere RA 《Physical review letters》2008,101(18):182003
A precision measurement of the mass of the h_{c}(1P1) state of charmonium has been made using a sample of 24.5x10;{6} psi(2S) events produced in e;{+}e;{-} annihilation at the Cornell Electron Storage Ring (CESR). The reaction used was psi(2S)-->pi;{0}h_{c}, pi;{0}-->gammagamma, h_{c}-->gammaeta_{c}, and the reaction products were detected in the CLEO-c detector. Data have been analyzed both for the inclusive reaction and for the exclusive reactions in which eta_{c} decays are reconstructed in 15 hadronic decay channels. Consistent results are obtained in the two analyses. The averaged results of the present measurements are M(h_{c})=3525.28+/-0.19(stat.)+/-0.12(syst.) MeV, and B(psi(2S)-->pi;{0}h_{c})xB(h_{c}-->gammaeta_{c})=(4.19+/-0.32+/-0.45)x10;{-4}. Using the ;{3}P_{J} centroid mass, DeltaM_{hf}(1P) identical withM(chi_{cJ})-M(h_{c})=+0.02+/-0.19+/-0.13 MeV. 相似文献
344.
Adams GS Anderson M Cummings JP Danko I Hu D Moziak B Napolitano J He Q Insler J Muramatsu H Park CS Thorndike EH Yang F Artuso M Blusk S Khalil S Li J Mountain R Nisar S Randrianarivony K Sultana N Skwarnicki T Stone S Wang JC Zhang LM Bonvicini G Cinabro D Dubrovin M Lincoln A Naik P Rademacker J Asner DM Edwards KW Reed J Briere RA Ferguson T Ma JS Tatishvili G Vogel H Watkins ME Rosner JL Alexander JP Cassel DG Duboscq JE Ehrlich R Fields L Galik RS Gibbons L Gray R Gray SW Hartill DL 《Physical review letters》2008,101(10):101801
We report the first observation of the decay J/psi-->3gamma. The signal has a statistical significance of 6sigma and corresponds to a branching fraction of B(J/psi-->3gamma)=(1.2+/-0.3+/-0.2)x10;{-5}, in which the errors are statistical and systematic, respectively. The measurement uses psi(2S)-->pi;{+}pi;{-}J/psi events acquired with the CLEO-c detector operating at the CESR e;{+}e;{-} collider. 相似文献
345.
Malgorzata?Konopka Anna?Janaszewska Kayla?A.M.?Johnson David?Hedstrand Donald?A.?Tomalia Barbara?Klajnert-MaculewiczEmail authorView authors OrcID profile 《Journal of nanoparticle research》2018,20(8):220
A unique photoluminescent phenomenon producing inexplicable, blue emissions [λEx?=?365 nm; λEm?=?460 nm] in the absence of traditional aromatic fluorophores has been observed in a variety of surface functionalized poly(amidoamine) (PAMAM) dendrimers over the past two decades. This emission phenomenon, referred to as non-traditional intrinsic fluorescence (NTIF), originates from the intra-molecular clustering of electron-rich sub-fluorophores (i.e., tertiary amines and/or amido groups) residing in the interior of all PAMAM dendrimers. The intra-molecular clustering of these interior sub-fluorophores is hypothesized to account for the modest but reproducible, blue emissions observed for a variety of dendrimer surface moieties (i.e., –OH, –CO2H, and –NH2). Unexpectedly, a simple, one-step conversion of amine-terminated PAMAM dendrimers to 1-(4-carbomethyoxy) pyrrolidone-terminated dendrimers (4-CMP) was found to produce a 50-fold increase in blue NTIF emission compared to other surface moieties. In an effort to understand this new enhanced emission property, critical nanoscale design parameter (CNDP)-directed quenching experiments were devised to probe the increased NTIF emissions. Was it originating from the interior sub-fluorophoric tertiary amine/amido moieties or from the surface-attached, sub-fluorophoric pyrrolidone amido groups or both? Four generations of 4-CMP PAMAM dendrimers were examined. Two classical quenchers, namely, potassium iodide and acrylamide were selected to probe surface versus interior domains, respectively, as a function of predictable CNDPs associated with generation levels. With increasing dendrimer generation, quencher penetration into the dendrimer interior is impeded due to CNDP-directed generational congestion. Stern-Volmer plots for each quencher, as a function of generation, exhibited appropriate linear or non-linear correlations that corroborated behavior expected for two distinct region-specific emission sites. 相似文献