全文获取类型
收费全文 | 995篇 |
免费 | 22篇 |
国内免费 | 2篇 |
专业分类
化学 | 583篇 |
晶体学 | 16篇 |
力学 | 38篇 |
数学 | 73篇 |
物理学 | 309篇 |
出版年
2022年 | 9篇 |
2021年 | 15篇 |
2020年 | 12篇 |
2019年 | 15篇 |
2018年 | 21篇 |
2017年 | 15篇 |
2016年 | 26篇 |
2015年 | 19篇 |
2014年 | 33篇 |
2013年 | 56篇 |
2012年 | 63篇 |
2011年 | 75篇 |
2010年 | 54篇 |
2009年 | 44篇 |
2008年 | 62篇 |
2007年 | 69篇 |
2006年 | 51篇 |
2005年 | 41篇 |
2004年 | 24篇 |
2003年 | 29篇 |
2002年 | 24篇 |
2001年 | 15篇 |
2000年 | 14篇 |
1999年 | 11篇 |
1998年 | 9篇 |
1997年 | 15篇 |
1996年 | 7篇 |
1995年 | 6篇 |
1994年 | 7篇 |
1993年 | 9篇 |
1992年 | 6篇 |
1991年 | 6篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 10篇 |
1984年 | 10篇 |
1983年 | 10篇 |
1982年 | 5篇 |
1980年 | 6篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 8篇 |
1976年 | 5篇 |
1973年 | 9篇 |
1961年 | 4篇 |
1960年 | 4篇 |
1954年 | 7篇 |
排序方式: 共有1019条查询结果,搜索用时 468 毫秒
941.
Adams J Adler C Aggarwal MM Ahammed Z Amonett J Anderson BD Arkhipkin D Averichev GS Badyal SK Balewski J Barannikova O Barnby LS Baudot J Bekele S Belaga VV Bellwied R Berger J Bezverkhny BI Bhardwaj S Bhati AK Bichsel H Billmeier A Bland LC Blyth CO Bonner BE Botje M Boucham A Brandin A Bravar A Cadman RV Cai XZ Caines H Calderón de la Barca Sánchez M Carroll J Castillo J Cebra D Chaloupka P Chattopadhyay S Chen HF Chen Y Chernenko SP Cherney M Chikanian A Christie W Coffin JP Cormier TM 《Physical review letters》2005,95(15):152301
Charged hadrons in [EQUATION: SEE TEXT] associated with particles of [EQUATION: SEE TEXT] are reconstructed in pp and Au+Au collisions at sqrt[sNN]=200 GeV. The associated multiplicity and p magnitude sum are found to increase from pp to central Au+Au collisions. The associated p distributions, while similar in shape on the nearside, are significantly softened on the awayside in central Au+Au relative to pp and not much harder than that of inclusive hadrons. The results, consistent with jet quenching, suggest that the awayside fragments approach equilibration with the medium traversed. 相似文献
942.
We report the results of a comprehensive study of weak localization and electron-electron interaction effects in disordered V1−xPdx alloys whose compositions are close to the (low Tc) A15 V3Pd compound. Magnetoresistivity and zero field resistivity have been measured within the temperature range 1.5≤T≤300 K. The low-temperature resistivity obeys a law, which is explained by electron-electron interaction. We have determined the electron-phonon scattering time (τe-ph) for V1−xPdx alloys. Our results indicate an anomalous electron-phonon scattering rate obeying quadratic temperature dependence. This observation is interpreted by the existing theories of electron-phonon interactions. 相似文献
943.
We report a new and efficient ruthenium-catalyzed reaction that transforms ethynyl alcohol into alkene and carbon monoxide. The most efficient catalysts are TpRu(PPh3)(CH3CN)2PF6 (10 mol %) and lithium triflate (20 mol %). The mechanism of this reaction was elucidated using an isotope-labeling experiment. 相似文献
944.
K. Lal S. K. Chattopadhyay A.K. Meikap S.K. Chatterjee M. Ghosh 《Czechoslovak Journal of Physics》2003,53(3):263-270
AC conductivity of different thin zinc oxide films measured in the frequency range of 10 Hz to 2 MHz in the temperature interval of 300 K to 575 K is reported. ZnO films were prepared by reactive r.f. magnetron sputtering from ZnO target. The experimental data reveal that a.c. conductivity is proportional to
s
. The value of s was found to be temperature dependent, decreases with increasing temperature. These observations suggest that correlated barrier hopping model is the most likely mechanism. The temperature dependence of a.c. Conductivity is expressed in power law form as () T
n
. The temperature exponent n is found to be increasing with increasing temperature and decreasing frequency in accordance with the narrow band limit. At high temperature the conductivity variation with frequency is comparatively small. The polaron binding energy (W
m), the height of Coulomb barrier (W) and the characteristic relaxation time (0) have been calculated. The values of W
m and W increase as the thickness decreases whereas the values of 0 decrease with decreasing thickness. 相似文献
945.
Adams J Adler C Aggarwal MM Ahammed Z Amonett J Anderson BD Anderson M Arkhipkin D Averichev GS Badyal SK Balewski J Barannikova O Barnby LS Baudot J Bekele S Belaga VV Bellwied R Berger J Bezverkhny BI Bhardwaj S Bhaskar P Bhati AK Bichsel H Billmeier A Bland LC Blyth CO Bonner BE Botje M Boucham A Brandin A Bravar A Cadman RV Cai XZ Caines H Calderón de la Barca Sánchez M Carroll J Castillo J Castro M Cebra D Chaloupka P Chattopadhyay S Chen HF Chen Y Chernenko SP Cherney M Chikanian A Choi B 《Physical review letters》2003,91(7):072304
We report measurements of single-particle inclusive spectra and two-particle azimuthal distributions of charged hadrons at high transverse momentum (high p(T)) in minimum bias and central d+Au collisions at sqrt[s(NN)]=200 GeV. The inclusive yield is enhanced in d+Au collisions relative to binary-scaled p+p collisions, while the two-particle azimuthal distributions are very similar to those observed in p+p collisions. These results demonstrate that the strong suppression of the inclusive yield and back-to-back correlations at high p(T) previously observed in central Au+Au collisions are due to final-state interactions with the dense medium generated in such collisions. 相似文献
946.
Adler C Ahammed Z Allgower C Amonett J Anderson BD Anderson M Averichev GS Balewski J Barannikova O Barnby LS Baudot J Bekele S Belaga VV Bellwied R Berger J Bichsel H Billmeier A Bland LC Blyth CO Bonner BE Boucham A Brandin A Bravar A Cadman RV Caines H Calderón De La Barca Sánchez M Cardenas A Carroll J Castillo J Castro M Cebra D Chaloupka P Chattopadhyay S Chen Y Chernenko SP Cherney M Chikanian A Choi B Christie W Coffin JP Cormier TM Cramer JG Crawford HJ Deng WS Derevschikov AA 《Physical review letters》2003,90(3):032301
Azimuthal anisotropy (v(2)) and two-particle angular correlations of high p(T) charged hadrons have been measured in Au+Au collisions at sqrt[s(NN)]=130 GeV for transverse momenta up to 6 GeV/c, where hard processes are expected to contribute significantly. The two-particle angular correlations exhibit elliptic flow and a structure suggestive of fragmentation of high p(T) partons. The monotonic rise of v(2)(p(T)) for p(T)<2 GeV/c is consistent with collective hydrodynamical flow calculations. At p(T)>3 GeV/c, a saturation of v(2) is observed which persists up to p(T)=6 GeV/c. 相似文献
947.
J. W. Kooi G. Chattopadhyay S. Withington F. Rice J. Zmuidzinas C. Walker G. Yassin 《International Journal of Infrared and Millimeter Waves》2003,24(3):261-284
We describe a waveguide to thin-film microstrip transition for high-performance submillimetre wave and teraherz applications. The proposed constant-radius probe couples thin-film microstrip line, to full-height rectangular waveguide with better than 99% efficiency (VSWR 1.20) and 45% fractional bandwidth. Extensive HFSS simulations, backed by scale-model measurements, are presented in the paper. By selecting the substrate material and probe radius, any real impedance between 15-60 can be achieved. The radial probe gives significantly improved performance over other designs discussed in the literature. Although our primary application is submillimetre wave superconducting mixers, we show that membrane techniques should allow broad-band waveguide components to be constructed for the THz frequency range. 相似文献
948.
Adler C Ahammed Z Allgower C Amonett J Anderson BD Anderson M Averichev GS Balewski J Barannikova O Barnby LS Baudot J Bekele S Belaga VV Bellwied R Berger J Bichsel H Bland LC Blyth CO Bonner BE Bossingham R Boucham A Brandin A Caines H Calderón De La Barca Sánchez M Cardenas A Carroll J Castillo J Castro M Cebra D Chattopadhyay S Chen ML Chen Y Chernenko SP Cherney M Chikanian A Choi B Christie W Coffin JP Conin L Cormier TM Cramer JG Crawford HJ DeMello M Deng WS Derevschikov AA Didenko L 《Physical review letters》2001,87(11):112303
The minimum-bias multiplicity distribution and the transverse momentum and pseudorapidity distributions for central collisions have been measured for negative hadrons ( h(-)) in Au+Au interactions at square root of ([s(NN)]) = 130 GeV. The multiplicity density at midrapidity for the 5% most central interactions is dN(h(-))/d(eta)/(eta = 0) = 280+/-1(stat)+/-20(syst), an increase per participant of 38% relative to pp collisions at the same energy. The mean transverse momentum is 0.508+/-0.012 GeV/c and is larger than in central Pb+Pb collisions at lower energies. The scaling of the h(-) yield per participant is a strong function of p( perpendicular). The pseudorapidity distribution is almost constant within /eta/<1. 相似文献
949.
950.
J. W. Kooi J. A. Stern G. Chattopadhyay H. G. LeDuc B. Bumble J. Zmuidzinas 《International Journal of Infrared and Millimeter Waves》1998,19(3):373-383
Recent results at 1 THz using normal-metal tuning circuits have shown that SIS mixers can work well up to twice the gap frequency of the junction material (niobium). However, the performance at 1 THz is limited by the substantial loss in the normal metal films. For better performance superconducting films with a higher gap frequency than niobium and with low RF loss are needed. Niobium nitride has long been considered a good candidate material, but typical NbN films suffer from high RF loss. To circumvent this problem we are currently investigating the RF loss in NbTiN films, a 15K Tc compound superconductor, by incorporating them into quasi-optical slot antenna SIS devices. 相似文献