全文获取类型
收费全文 | 430篇 |
免费 | 14篇 |
国内免费 | 1篇 |
专业分类
化学 | 158篇 |
晶体学 | 4篇 |
力学 | 9篇 |
数学 | 13篇 |
物理学 | 202篇 |
无线电 | 59篇 |
出版年
2023年 | 2篇 |
2022年 | 8篇 |
2021年 | 6篇 |
2020年 | 5篇 |
2019年 | 9篇 |
2018年 | 7篇 |
2017年 | 4篇 |
2016年 | 16篇 |
2015年 | 2篇 |
2014年 | 13篇 |
2013年 | 18篇 |
2012年 | 22篇 |
2011年 | 18篇 |
2010年 | 12篇 |
2009年 | 15篇 |
2008年 | 25篇 |
2007年 | 20篇 |
2006年 | 19篇 |
2005年 | 11篇 |
2004年 | 10篇 |
2003年 | 10篇 |
2002年 | 18篇 |
2001年 | 3篇 |
2000年 | 12篇 |
1999年 | 7篇 |
1998年 | 5篇 |
1997年 | 7篇 |
1996年 | 10篇 |
1995年 | 5篇 |
1994年 | 11篇 |
1993年 | 7篇 |
1992年 | 16篇 |
1991年 | 9篇 |
1990年 | 11篇 |
1989年 | 9篇 |
1988年 | 5篇 |
1987年 | 9篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1984年 | 6篇 |
1983年 | 14篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1974年 | 2篇 |
1972年 | 1篇 |
1960年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有445条查询结果,搜索用时 0 毫秒
1.
We present a general scheme for entangling any degree of freedom of two uncorrelated identical particles from independent
sources by a combination of two-particle interferometry and which-way detection. We show that this entanglement generation
procedure works for completely random initial states of the variable to be entangled. We also demonstrate a curious complementarity
exhibited by our scheme and its applications in estimating the generated entanglement as a function of wave packet overlap
at the beamsplitter. 相似文献
2.
R. Adhikari A. Sil A. Raychaudhuri 《The European Physical Journal C - Particles and Fields》2002,25(1):125-130
We present a solution of the solar neutrino deficit using three flavors of neutrinos and R-parity non-conserving supersymmetry. In this model, in vacuum, the is massless and unmixed, mass and mixing being restricted to the - sector only, which we choose in consistency with the requirements of the atmospheric neutrino anomaly. The flavor changing
and flavor diagonal neutral currents present in the model and the three-flavor picture together produce an energy dependent
resonance-induced - mixing in the sun. This mixing plays a key role in the new solution to the solar neutrino problem. The best fit to the solar
neutrino rates and spectrum (1258-day SK and 241-day SNO data) requires a mass square difference of eV2 in vacuum between the two lightest neutrinos. This solution cannot accommodate a significant day-night effect for solar neutrinos
nor CP violation in terrestrial neutrino experiments.
Received: 26 December 2001 / Revised version: 16 February 2002 / Published online: 26 July 2002 相似文献
3.
We show by general considerations that it is not possible to test violation of the existing versions of Bell’s inequality
in entangled neutral kaons system using experimentally accessible thin regenerators. We point out the loophole in the recent
argument (A Bramon and M Nowakowski, Phys. Rev. Lett.
83, 1 (1999)) that claimed such a test to be possible. 相似文献
4.
This paper presents an ATM-based transport architecture for next-generation multiservices personal communication networks (PCN). Such “multimedia capable” integrated services wireless networks are motivated by an anticipated demand for wireless extensions to future broadband networks. An ATM compatible wireless network concept capable of supporting a mix of broadband ISDN services including constant bit-rate (CBR), variable bit-rate (VBR), and packet data transport is explored from an architectural viewpoint. The proposed system uses a hierarchical ATM switching network for interconnection of PCN microcells, each of which is serviced by high-speed, shared-access radio links based on ATM-compatible cell, relay principles. Design issues related to the physical (modulation), media access control (MAC), and data-link layers of the ATM-based radio link are discussed, and preliminary technical approaches are identified in each case. An example multiservice dynamic reservation (MDR) TDMA media access protocol is then considered in further detail, and simulation results are presented for an example voice/data scenario with a proportion of time-critical (i.e., multimedia) packet data. Time-of-expiry (TOE) based queue service disciplines are also investigated as a mechanism for improving the quality-of-service (QoS) in this scenario 相似文献
5.
From flash photolysis data of benzil and 2,2′-dichlorobenzil, the role of conformeric triplets in the formation of hydrogen
adduct radicals has been discussed. The planar relaxed triplet absorbing at 470 nm is less efficient in forming a hydrogen
adduct radical as compared to its puckered conformeric partner. Among the hydrogen donors, triethyl amine and isopropanol,
the former is more efficient in converting puckered triplets and less efficient in the case of planar conformers. Absorptions
of radicals and radical anions of 2,2′-dichlorobenzil appear at 355 nm and 460 nm respectively. These are blue-shifted as
compared to those of the parent compound benzil appearing at 370 nm and 540 nm, respectively. This blue-shift has been discussed
in terms of steric hindrance due to ortho-substitution. 相似文献
6.
Raj Gandhi Kamales Kar S. Uma Sankar Abhijit Bandyopadhyay Rahul Basu Pijushpani Bhattacharjee Biswajoy Brahmachari Debrupa Chakraborti M. Chaudhury J. Chaudhury Sandhya Choubey E. J. Chun Atri Desmukhya Anindya Datta Gautam Dutta Sukanta Dutta Anjan Giri Sourendu Gupta Srubabati Goswami Namit Mahajan H. S. Mani A. Mukherjee Biswarup Mukhopadhyaya S. N. Nayak M. Randhawa Subhendu Rakshit Asim K. Ray Amitava Raychaudhuri D. P. Roy Probir Roy Suryadeep Roy Shiv Sethi G. Sigl Arunansu Sil N. Nimai Singh Mark Vagins Urjit Yagnik 《Pramana》2003,60(2):405-409
This is the report of neutrino and astroparticle physics working group at WHEPP-7. Discussions and work on CP violation in
long baseline neutrino experiments, ultra high energy neutrinos, supernova neutrinos and water Cerenkov detectors are discussed. 相似文献
7.
Reininger D.J. Dipankar Raychaudhuri Hui J.Y. 《Selected Areas in Communications, IEEE Journal on》1996,14(6):1076-1086
A scheme for delivery or variable bit-rate (VBR) video over asynchronous transfer mode (ATM) networks where bandwidth can be renegotiated during the duration of a call between the video source and the network is considered. Renegotiation can be initiated by either the video source or the network. The video bandwidth requirement is characterized by a usage parameter control (UPC) consisting, in general, of peak rate, burst length, and sustained rate. A baseline design is outlined where rate-control adjusts the source's rate while a new UPC is requested from the network. When granted, the new UPC allows the source to maintain its target quantization and delay requirements. Rate control epochs may be extended when the network blocks UPC requests or sets a lower UPC value to temporally deal with congestion. Simulation results are presented for VBR MPEG video. The results show that with a moderate renegotiation rate the scheme tracks the bandwidth requirements of the source. As a result, the video quality and bandwidth efficiency can be maintained 相似文献
8.
Amitava Datta Monoranjan Guchait Amitava Raychaudhuri 《Zeitschrift fur Physik C Particles and Fields》1992,54(3):513-517
The allowed regions in the chargino-gluino mass plane are mapped out using the latestZ decay data from experiments. The determination of these masses in future experiments will uniquely fix the neutralino mass spectrum for a fixedv
1/v
2. Since the usual two-fold ambiguity is removed by LEP data for gluino masses upto 200 GeV. Constraints have also been placed on neutralino masses. 相似文献
9.
10.
The electronegativities () of some 36 atoms/groups (including some 6 ionic ones) X are calculated from the atomic charges in the corresponding methyl species CH3X that were obtained by applying Bader's theory of atoms in molecules. The numerical values of the for the various groups studied are reasonable and correlate linearly with the two existing experimental scales for group electronegativity, Inamoto's i scale and the 1JCC (ortho-ipso) coupling constants in the monosubstituted benzenes, to satisfactory extents. The relations between the values and some “critical properties” of the various CH3X molecules considered are also studied. It is suggested that in a molecule PX, rP/R where rP is the distance of Bader's critical point on the bond PX of length R from the atom P or the binding atom of the group P can be a very good measure of the electronegativity of the atom/group X. © 1992 by John Wiley & Sons, Inc. 相似文献