全文获取类型
收费全文 | 499篇 |
免费 | 12篇 |
国内免费 | 5篇 |
专业分类
化学 | 315篇 |
晶体学 | 3篇 |
力学 | 2篇 |
数学 | 42篇 |
物理学 | 154篇 |
出版年
2023年 | 4篇 |
2022年 | 7篇 |
2021年 | 16篇 |
2020年 | 6篇 |
2019年 | 11篇 |
2018年 | 2篇 |
2017年 | 5篇 |
2016年 | 10篇 |
2015年 | 12篇 |
2014年 | 11篇 |
2013年 | 28篇 |
2012年 | 18篇 |
2011年 | 37篇 |
2010年 | 24篇 |
2009年 | 21篇 |
2008年 | 20篇 |
2007年 | 25篇 |
2006年 | 21篇 |
2005年 | 24篇 |
2004年 | 10篇 |
2003年 | 14篇 |
2002年 | 20篇 |
2001年 | 10篇 |
2000年 | 8篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 6篇 |
1996年 | 9篇 |
1995年 | 2篇 |
1992年 | 14篇 |
1991年 | 7篇 |
1990年 | 2篇 |
1989年 | 7篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 10篇 |
1983年 | 9篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1978年 | 2篇 |
1977年 | 8篇 |
1976年 | 8篇 |
1975年 | 4篇 |
1974年 | 7篇 |
1973年 | 4篇 |
1972年 | 3篇 |
1967年 | 2篇 |
排序方式: 共有516条查询结果,搜索用时 15 毫秒
61.
Summary Kinetics of formation of ternary complexes in the reaction of Ni(NTA)(H2O)
2
–
with several amino acids, LH± (glycine, -alanine, -alanine, L-valine and L-phenylalanine) have been studied by a pH indicator method using stopped-flow spectrophotometry. The results conform to 1/kobs = 1/k + [H+]/ kKTL where K is the equilibrium constant for formation of Ni(NTA)(–L)(H2O)2–, and k is the specific rate constant for the subsequent rate-determining ring-closure step leading to Ni(NTA)(=L)2–. For the different amino acids studied, the k values decrease in the sequence: glycine > -alanine > L-phenylalanine > L-valine > -alanine. These k values areca. 1000 times lower than the values for complexation of Ni(NTA)(H2O)
2
–
with NH3 and imidazole and the spread in k values is much less than the pKa values of the amino acids. The relative rates are enthalpy controlled and the S values are highly negative in conformity with ring closure as the rate determining step. 相似文献
62.
Zoltan Papp 《Archiv der Mathematik》1977,29(1):235-240
63.
The electron energy loss spectrum of a clean Cu(311) surface has been studied by reflected electrons using primary energies between 30 and 300 eV. The losses obtained are compared with literature values. Loss spectra with adsorbed CO and Xe are also reported. Some assignments of the loss mechanisms have been attempted. 相似文献
64.
65.
E. Papp 《Physics letters. A》1984,100(2):74-76
The critical coupling constant characterizing the stability behaviour of the Coulomb quasipotential has been evaluated as α ? αc = 2. The present stability approach is based on the quantum-mechanical controllability requirement of the dispersion shifts due to the interactions. The dispersions characterizing the Coulomb quasipotential have been established suitably within the high-energy euclidian region. 相似文献
66.
We report on the observation of ultracold heteronuclear Feshbach molecules. Starting with a 87Rb Bose-Einstein condensate and a cold atomic gas of 85Rb, we utilize previously unobserved interspecies Feshbach resonances to create up to 25,000 molecules. Even though the 85Rb gas is nondegenerate, we observe a large molecular conversion efficiency due to the presence of a quantum degenerate 87Rb gas; this represents a key feature of our system. We compare the molecule creation at two different Feshbach resonances with different magnetic-field widths. The two Feshbach resonances are located at 265.44+/-0.15 G and 372.4+/-1.3 G. We also directly measure the small binding energy of the molecules through resonant magnetic-field association. 相似文献
67.
Ken Takayama Senri Soma Taiji Inoue Hideaki Kakinuma Takashi Haraguchi Kaoru Suzuki 《Applied Physics A: Materials Science & Processing》2010,101(4):727-733
Phosphorus-doped diamond-like carbon (DLC) films were deposited on quartz and p-type silicon (p-Si) substrates by pulsed-laser
deposition. Open-circuit voltage (V
oc) and short-circuit density (I
sc/cm2) from a heating process converted from one type of electrode to another and the two types of electrode pattern are shown
by the V–I characteristics. The first heating process was by a ceramic heater, and the other was by an infrared heater. We adopted two
electrode patterns, from a bipectinate electrode and a plot pattern electrode, to measure electric photovoltaic characteristics.
We were able to upgrade V
oc and I
sc/cm2 to 35∼45 mV, and 0.24 μA/cm2, respectively, under infrared heating. V
oc by the plot pattern electrode was over 2 V under infrared heating and ceramic heating did not match this on deposition by
the PLD method. 相似文献
68.
69.
The giant magnetoresistance effect is investigated in a two-dimensional electron gas modulated by periodically repeated magnetic barriers, which can be realized by depositing parallel ferromagnets on the top and the bottom of a heterostructure. It is found that the magnetoresistance ratio (MRR) of the present system shows a strong dependence on the number of ferromagnetic unit cells. The modified MRR (MMRR) shows oscillations, where the number of peaks is determined by the number of units, and our study indicates that for experimentally accessible parameters for a GaAs heterostructure the value of the MMRR can be as high as 55% for a realistic electron density. 相似文献
70.
We study a nonlinear elliptic problem with non-local boundary conditions and variable exponent. We prove an existence and uniqueness result of weak solution to this problem with general maximal monotone graphs. 相似文献