全文获取类型
收费全文 | 1090篇 |
免费 | 27篇 |
国内免费 | 76篇 |
专业分类
化学 | 258篇 |
晶体学 | 4篇 |
力学 | 17篇 |
数学 | 45篇 |
物理学 | 869篇 |
出版年
2020年 | 3篇 |
2018年 | 5篇 |
2017年 | 7篇 |
2016年 | 22篇 |
2015年 | 13篇 |
2014年 | 15篇 |
2013年 | 8篇 |
2012年 | 11篇 |
2011年 | 78篇 |
2010年 | 50篇 |
2009年 | 41篇 |
2008年 | 40篇 |
2007年 | 35篇 |
2006年 | 56篇 |
2005年 | 78篇 |
2004年 | 96篇 |
2003年 | 109篇 |
2002年 | 54篇 |
2001年 | 39篇 |
2000年 | 21篇 |
1999年 | 40篇 |
1998年 | 12篇 |
1997年 | 15篇 |
1996年 | 19篇 |
1995年 | 19篇 |
1994年 | 12篇 |
1993年 | 21篇 |
1992年 | 15篇 |
1991年 | 7篇 |
1990年 | 22篇 |
1989年 | 28篇 |
1988年 | 34篇 |
1987年 | 18篇 |
1986年 | 24篇 |
1985年 | 13篇 |
1984年 | 15篇 |
1983年 | 10篇 |
1982年 | 7篇 |
1981年 | 15篇 |
1980年 | 8篇 |
1979年 | 8篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1968年 | 4篇 |
1963年 | 4篇 |
1935年 | 2篇 |
1931年 | 2篇 |
1930年 | 3篇 |
1928年 | 2篇 |
1893年 | 2篇 |
排序方式: 共有1193条查询结果,搜索用时 31 毫秒
991.
Search for electron antineutrino interactions with the Borexino Counting Test Facility at Gran Sasso
Electron antineutrino interactions above the inverse beta decay energy of protons (Eν̄e>1.8 MeV) were looked for with the Borexino counting test facility (CTF). One candidate event survived after rejection of
background, which included muon-induced neutrons and random coincidences. An upper limit on the solar ν̄e flux, assumed having the 8B solar neutrino energy spectrum, of 1.1×105 cm-2 s-1 (90% C.L.) was set with a 7.8 ton × year exposure. This upper limit corresponds to a solar neutrino transition probability,
νe→ν̄e, of 0.02 (90% C.L.). Predictions for antineutrino detection with Borexino, including geoneutrinos, are discussed on the basis
of background measurements performed with the CTF.
PACS 13.15.+g, 14.60.St, 13.40.Em, 96.60.Hv, 96.60.qd, 23.40.Bw 相似文献
992.
The TileCal System of the ATLAS Collaboration C. Alexa et al. 《The European Physical Journal C - Particles and Fields》2003,28(3):297-304
The energy spectrum and the cross section of photonuclear interactions of 180 GeV muons in iron were measured at the CERN
SPS using prototype modules of the ATLAS hadron calorimeter. The differential cross section for a muon fractional energy loss was measured in the range 0.1<v<1. The integrated cross section is cm2g-1 in agreement with the theoretical prediction of cm2g-1. The best adjustment of the data to the theory is achieved for the value of of the photon-nucleon cross section for photons with energies in the range from 18 to 180 GeV.
Received: 22 January 2003 / Published online: 5 May 2003 相似文献
993.
利用北京谱仪(BES)在北京正负电子对撞机(BEPC)e+e-对撞质心系能量为4.03GeV处收集的积分亮度为22.3pb-1的数据,测量了带电及中性D介子的单举半轻子(电子)衰变的分支比.分析中采用了“联合D0和D+单双标记”的方法,测得D-和D0单举半轻子(电子)衰变的分支比分别为BF(D-→e-X)=(21.8±8.5±4.2)%,BF(D0→e-X)=(8.9±3.0±1.6)%,其相对比值为BF(D-→e-X)BF(D0→e-X)=2.4±1.7±0.8. 相似文献
994.
995.
Jets are collimated sprays of particles originating from fragmentation of high energy partons produced in a hard collision. They are an important diagnostic tool in studies of the Quark Gluon Plasma (QGP). The modification of the jet fragmentation pattern and its structure is a signature for the influence of hot and dense matter on the parton fragmentation process. Jet measurements in proton-proton collisions provide a baseline for similar measurements in heavy-ion collisions, while studies in proton-nucleus system allow to estimate cold nuclear matter effects. Here we present jet studies in different colliding systems (p–p, p–Pb, Pb–Pb) performed by the ALICE collaboration at LHC energies. Results on jet spectra, cross sections, nuclear modification factors, jet structure and other kinematic observables will be presented. 相似文献
996.
997.
998.
Amide,which is derived from proline and is inexpensive and air-stable,has been synthesized and characterized by 1H NMR,13C NMR,and MS.It was found to be an efficient ligand in the palladium-catalyzed Suzuki cross-coupling reaction.In the Pd/amide catalytic system,aryl bromides can be coupled with phenylboronic acid in ethanol/water(1:2;v/v) in excellent yields even with a low Pd loading of 0.01 mol%.Moreover,the scope of the reaction is broad,and a wide variety of functional groups are tolerant. 相似文献
999.
<正>Highly active calcium chloride(CaCl_2) doped Zn-Co~Ⅲdouble metal-cyanide(Ca-DMC) catalysts were firstly reported.Ca-DMCs presented a very higher polymer yield(54 kg polymer/g catalyst) at relative low temperature(80-115℃) toward ringopening polymerization(ROP) of propylene oxide(PO) than did DMC catalysts without modification. 相似文献
1000.
Titanium dioxide was deposited from aqueous suspension onto cellulosic surfaces.Titania was sourced from Degussa (P25TM,70:30 anatase:rutile).Dry uptake of particles was shown to be rapid and dominant with one-third of the deposition occurring in less than 30 s and over one-half in the first minute.Isotherms were recorded to compare the rate of titanium deposition on dry and pre-wetted cotton.In the dry case uptake reached a maximum in 30 min whereas in the pre-wetted case the uptake was seen to continue beyond 180 min.A broad trend of higher deposition occurring at lower pH was seen,corresponding to the region where surface charges were opposite and thus attractive.Dry pickup was less significant at high pH.The response to varying ionic strength was complex and was attributed to the combined effect of charge screening,particle aggregation and consequent particle entrapment or occlusion.Titania deposition into the interstices of woven cotton sheets resulted in the formation of inorganic,nanoparticulate skeletons which could be isolated by controlled combustion of the cellulose and thus cotton was suggested to have potential for the templated synthesis of high surface area semiconductor materials. 相似文献