全文获取类型
收费全文 | 641篇 |
免费 | 26篇 |
国内免费 | 3篇 |
专业分类
化学 | 340篇 |
晶体学 | 11篇 |
力学 | 10篇 |
数学 | 29篇 |
物理学 | 280篇 |
出版年
2023年 | 4篇 |
2022年 | 5篇 |
2021年 | 6篇 |
2020年 | 9篇 |
2019年 | 18篇 |
2018年 | 18篇 |
2017年 | 10篇 |
2016年 | 15篇 |
2015年 | 13篇 |
2014年 | 31篇 |
2013年 | 60篇 |
2012年 | 36篇 |
2011年 | 52篇 |
2010年 | 24篇 |
2009年 | 29篇 |
2008年 | 30篇 |
2007年 | 25篇 |
2006年 | 23篇 |
2005年 | 26篇 |
2004年 | 14篇 |
2003年 | 9篇 |
2002年 | 19篇 |
2001年 | 12篇 |
2000年 | 8篇 |
1999年 | 7篇 |
1998年 | 9篇 |
1997年 | 4篇 |
1996年 | 17篇 |
1995年 | 17篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 13篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 2篇 |
1986年 | 4篇 |
1985年 | 7篇 |
1984年 | 9篇 |
1983年 | 14篇 |
1982年 | 6篇 |
1981年 | 3篇 |
1980年 | 8篇 |
1979年 | 6篇 |
1978年 | 7篇 |
1977年 | 2篇 |
1975年 | 4篇 |
1960年 | 1篇 |
1958年 | 1篇 |
1938年 | 2篇 |
排序方式: 共有670条查询结果,搜索用时 46 毫秒
51.
52.
Effect of denaturation of DNA on the molecular organization of a fluorescent dye in ultra thin films
Acridine Orange (AO) forms H-dimer in solid state and in ultra thin films. However, H dimer of AO reduces its efficiency as a usefull material for fluorescence probe. In the present work detailed investigations has been done on the interaction of AO with different forms of DNA in order to check the effectiveness in controlling the dimeric sites of AO in the Layer by Layer (LbL) self assembled film. It was found that single stranded DNA (ssDNA) is most effective than the dsDNA and coil-shaped DNA in controlling the dimeric sites of AO in LbL film. 相似文献
53.
Evolution of a dust void in a radio-frequency plasma sheath 总被引:1,自引:0,他引:1
Dahiya RP Paeva GV Stoffels WW Stoffels E Kroesen GM Avinash K Bhattacharjee A 《Physical review letters》2002,89(12):125001
The onset and growth of a dust void are investigated in a radio-frequency (rf) sheath of a capacitively coupled argon plasma. A circularly symmetric void emerges and grows with increasing rf power and pressure in the central region of the dust cloud levitating in the sheath. Experimental measurements of the void diameter are compared with the predictions of a simple phenomenological theory, based on a balance of forces on dust grains. 相似文献
54.
Abazov VM Abbott B Abdesselam A Abolins M Abramov V Acharya BS Adams DL Adams M Ahmed SN Alexeev GD Alves GA Amos N Anderson EW Arnoud Y Baarmand MM Babintsev VV Babukhadia L Bacon TC Baden A Baldin B Balm PW Banerjee S Barberis E Baringer P Barreto J Bartlett JF Bassler U Bauer D Bean A Beaudette F Begel M Belyaev A Beri SB Bernardi G Bertram I Besson A Beuselinck R Bezzubov VA Bhat PC Bhatnagar V Bhattacharjee M Blazey G Blessing S Boehnlein A Bojko NI Borcherding F Bos K Brandt A Breedon R 《Physical review letters》2002,88(17):171802
We have performed a search for scalar top quark (stop) pair production in the inclusive electron-muon-missing transverse energy final state, using a sample of pp events corresponding to 108.3 pb(-1) of data collected with the D0 detector at Fermilab. The search is done in the framework of the minimal supersymmetric standard model assuming that the sneutrino is the lightest supersymmetric particle. For the dominant decays of the lightest stop, t-->b chi+1 and t-->blnu, no evidence for signal is found. We derive cross-section limits as a function of stop ( t ), chargino ( chi+1), and sneutrino ( nu) masses. 相似文献
55.
In this paper, we consider several constructions which from a given B-product *
B
lead to another one
We shall be interested in finding what algebraic properties of the ring
are shared also by the ring
. In particular, for some constructions the rings R
B and
will be isomorphic and therefore have the same algebraic properties. 相似文献
56.
A. K. Jain Bhattacharjee V. Kolandai Velu 《Reaction Kinetics and Catalysis Letters》1984,26(3-4):235-243
A modification in the reaction mechanism of 0-(2,4-dinitrophenyl)cyclohexanone Oxime with OH– in 30% aqueous methanol is suggested. The cationic micelles of cetyltrimethyl ammonium bromide enhance the reaction by a factor ofca. 3. The pseudo first order rate constant at the micellar surface was found to be 10.9×10–4 s–1 at 35±0.1°C. Anionic and nonionic micelles inhibit the rate of the reaction. Bromide ion inhibits the catalysis, which indicates that catalysis is partially due to a concentration effect. The catalytic efficiency increases with decreasing [OH–), which implies that the efficiency of the surfactant could be related to some standard parameter(s).
0-(2,4-)-- OH– 30%- . . 3. - 10.9·10–4 –1 35±0.1°C. . . , - . - [OH–], , - - .相似文献
57.
Calculations of the nonequilibrium rate constant for the model system H2O2 + M → 2 OH + M over the temperature range of 300–1900°K, assuming that only vibrational, or that both vibrational and rotational, energy is transferred in a collision, show that (1) inefficient energy transfer leads to a distinctly non-Arrhenius temperature dependence, the nonlinearity being in principle different for different M, and (2) despite different activation energies for different M, the order of M efficiencies is preserved throughout the temperature range. A reversal of M efficiencies can occur only if there is a change of mechanism of the reaction over the temperature range investigated. 相似文献
58.
Bernstein-Greene-Kruskal modes in a three-dimensional (3D) unmagnetized plasma are constructed. It is shown that 3D solutions that depend only on energy do not exist. However, 3D solutions that depend on energy and additional constants of motion (such as angular momentum) do exist. Exact analytical as well as numerical solutions are constructed assuming spherical symmetry, and their properties are contrasted with those of 1D solutions. Possible extensions to solutions with cylindrical symmetry with or without a finite magnetic guide field are discussed. 相似文献
59.
Kinetic eigenmodes of plasma oscillations in a weakly collisional plasma, described by a collision operator of the Fokker-Planck type, are obtained in closed form for initial-value as well as for boundary-value problems. These eigenmodes, which are smooth and compose a complete discrete spectrum, play the same role for weakly collisional plasmas as the Case-Van Kampen modes do for collisionless plasmas. 相似文献
60.
A nonlinear time-dependent model for void formation in colloidal plasmas is proposed. For experimentally relevant initial conditions, the model describes the nonlinear evolution of a zero-frequency linear instability that grows rapidly in the nonlinear regime and subsequently saturates to form a void. A number of features of the model are consistent with experimental observations under laboratory and microgravity conditions. 相似文献