全文获取类型
收费全文 | 187篇 |
免费 | 2篇 |
专业分类
化学 | 89篇 |
晶体学 | 2篇 |
力学 | 1篇 |
数学 | 14篇 |
物理学 | 83篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 5篇 |
2020年 | 3篇 |
2019年 | 2篇 |
2018年 | 1篇 |
2017年 | 3篇 |
2016年 | 5篇 |
2015年 | 1篇 |
2014年 | 1篇 |
2013年 | 14篇 |
2012年 | 4篇 |
2011年 | 9篇 |
2010年 | 1篇 |
2009年 | 3篇 |
2008年 | 5篇 |
2007年 | 10篇 |
2006年 | 8篇 |
2005年 | 7篇 |
2004年 | 8篇 |
2003年 | 7篇 |
2002年 | 6篇 |
2001年 | 7篇 |
2000年 | 4篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 6篇 |
1978年 | 7篇 |
1977年 | 1篇 |
1976年 | 6篇 |
1975年 | 2篇 |
1974年 | 4篇 |
1972年 | 1篇 |
1939年 | 2篇 |
1933年 | 2篇 |
排序方式: 共有189条查询结果,搜索用时 46 毫秒
131.
Stallinger S Reitsamer C Schuh W Kopacka H Wurst K Peringer P 《Chemical communications (Cambridge, England)》2007,(5):510-512
The reaction of PdCl2, dppm and CS2 in CH(2)Cl(2)/MeOH results in the palladium carbodiphosphorane complex [Pd(Ph(2)PCH(2)Ph(2)PCPPh(2)CH(2)PPh(2)-P,C,P)Cl]Cl. 相似文献
132.
W. G. Schaposchnikow B. D. Tschebotarow Hans Wolff G. Zeidler M. Rangaswami H. K. Sen E. J. Parry G. W. Ferguson W. C. Norris E. Roßmann H. Wagner E. F. Hickson A. V. Blom E. A. Schuh H. C. Theuerer S. Papkow W. A. Koehler R. O. Burford I. G. Farbenindustrie A. -G. M. P. Biget M. Ballay S. G. Clarke 《Analytical and bioanalytical chemistry》1939,116(5-6):209-215
133.
A. Rogl K. F. Renk B. I. Stahl C. Reichl D. Schuh W. Wegscheider 《International Journal of Infrared and Millimeter Waves》2008,29(10):906-913
We report on a subterahertz superlattice parametric oscillator that operated simultaneously at two different harmonic frequencies
of a microwave pump field. A pump field (frequency near 100 GHz) was coupled to a GaAs/AlAs superlattice in a resonator for
the third and the fifth harmonic. The pump field produced a third harmonic field and this together with the pump field created
a fifth harmonic field. A theoretical analysis indicates that the nonlinearity, which is based on the dynamics of miniband
electrons, should allow for the upconversion of pump radiation of higher frequency into the terahertz frequency range.
相似文献
134.
R.D. Wiersma J.G.S. Lok S. Kraus W. Dietsche K. von Klitzing D. Schuh M. Bichler H.-P. Tranitz W. Wegscheider 《Physica E: Low-dimensional Systems and Nanostructures》2006,34(1-2):16
We observe the total filling factor νT=1 exciton condensate in independently contacted bilayer two-dimensional electron systems in samples with minute tunnel coupling. At balanced electron densities in the layers, we find for both drag and counter-flow current configurations, thermally activated transport with a monotonic increase of the activation energy for d/ℓB<1.65 with activation energies up to 0.4 K. In the imbalanced system the activation energies show a striking asymmetry around the balance point, implying that the gap to charge excitations is considerably different in the separate layers that form the bilayer condensate. This indicates that the measured activation energy is neither the binding energy of the excitons, nor their condensation energy. 相似文献
135.
W. G. Schaposchnikow B. D. Tschebotarow Hans Wolff G. Zeidler M. Rangaswami H. K. Sen E. J. Parry G. W. Ferguson W. C. Norris E. Roßmann H. Wagner E. F. Hickson A. V. Blom E. A. Schuh H. C. Theuerer S. Papkow W. A. Koehler R. O. Burford I. G. Farbenindustrie A. -G. M. P. Biget M. Ballay und S. G. Clarke 《Fresenius' Journal of Analytical Chemistry》1939,116(5-6):209-215
Ohne Zusammenfassung 相似文献
136.
A theory is presented for the calculation of equilibrium properties of superconductors containing magnetic impuritiesof finite concentration. The theory is based on the Nagaoka-Suhl approach to thes — d model and treats finite impurity concentrations within a self-consistentT-matrix-approximation. An integral equation is derived for the pairbreaking parameter which describes de-pairing of Cooper pairs by spin flip scattering. Numerical solutions of this equation are used to compute the phase diagram in the temperature-concentration-plane and the transition-temperature-dependence of the upper critical field. These calculations are in good agreement with experimental data on LaCeAl2-samples. In addition, the recent discovery of three normal superconducting transitions in LaCeY is discussed quantitatively.Work performed within the research program of the Sonderforschungsbereich 125 Aachen/Jülich/Köln 相似文献
137.
B. Schuh 《Zeitschrift für Physik B Condensed Matter》1978,31(1):55-61
The transition temperature of the square lattice Ising antiferromagnet at finite magnetic field is calculated by three different approximations within the real space renormalization group approach. The most refined approximation is an extension of Kadanoff's potential moving method to a larger cell-size. The results of this approximation are in good agreement with recent Monte Carlo simulations and the Müller-Hartmann/Zittartz conjecture for the phase boundary. 相似文献
138.
Pedro S. Pereira Carlos Vinicius B. Oliveira Ana J. Maia Saulo R. Tintino Cícera Datiane de M. Oliveira-Tintino Maria C. Vega-Gomez Miriam Roln Cathia Coronel Antnia Eliene Duarte Luiz M. Barros Jeam Paul Kamdem Abolghasem Siyadatpanah Polrat Wilairatana Henrique D. M. Coutinho 《Molecules (Basel, Switzerland)》2021,26(15)
The species Cordia verbenacea DC (Boraginaceae), known as the whaling herb and camaradinha, is a perennial shrub species native to the Atlantic Forest. Its leaves are used in folk medicine as an anti-inflammatory, analgesic, antiulcerogenic and curative agent, in the form of teas or infusions for internal or topical use. The present study aimed to verify the cytotoxicity of the essential oil and the leishmanicidal and trypanocidal potential of C. verbenacea. The essential oil was characterized by GC-MS. The in vitro biological activity was determined by anti-Leishmania and anti-Trypanosoma assays. The cytotoxixity was determined using mammalian fibroblasts. The C. verbenacea species presented α-pinene (45.71%), β-caryophyllene (18.77%), tricyclo[2,2,1-(2.6)]heptane (12.56%) as their main compounds. The essential oil exhibited strong cytotoxicity at concentrations below 250 μg/mL (LC50 138.1 μg/mL) in mammalian fibroblasts. The potent anti-trypanosome and anti-promastigote activities occurred from the concentration of 62.5 μg/mL and was considered clinically relevant. The results also demonstrate that at low concentrations (<62.5 μg/mL), the essential oil of C. verbenacea managed to be lethal for these activities. This can be considered an indication of the power used in daily human consumption. Therefore, it can be concluded that the essential oil of C. verbenacea contains a compound with remarkable antiparasitic activities and requires further research. 相似文献
139.
Random percolation theory is a common basis for modelling intergranular phenomena such as cracking, corrosion or diffusion. However, crystallographic constraints in real microstructures dictate that grain boundaries are not assembled at random. In this work a Monte Carlo method is used to construct physically realistic networks composed of high-angle grain boundaries that are susceptible to intergranular attack, as well as twin-variant boundaries that are damage resistant. When crystallographic constraints are enforced, the simulated networks exhibit triple-junction distributions that agree with experiment and reveal the non-random nature of grain-boundary connectivity. The percolation threshold has been determined for several constrained boundary networks and is substantially different from the classical result of percolation theory; compared with a randomly assembled network, about 50-75% more resistant boundaries are required to break up the network of susceptible boundaries. Triple-junction distributions are also shown to capture many details of the correlated percolation problem and to provide a simple means of ranking microstructures. 相似文献
140.
Let (X
n
)
0 be a Markov chain with state space S=[0,1] generated by the iteration of i.i.d. random logistic maps, i.e., X
n+1=C
n+1
X
n
(1–X
n
),n0, where (C
n
)
1 are i.i.d. random variables with values in [0, 4] and independent of X
0. In the critical case, i.e., when E(log C
1)=0, Athreya and Dai(2) have shown that X
n
P
0. In this paper it is shown that if P(C
1=1)<1 and E(log C
1)=0 then(i) X
n
does not go to zero with probability one (w.p.1) and in fact, there exists a 0<<1 and a countable set (0,1) such that for all xA(0,1), P
x
(X
n
for infinitely many n1)=1, where P
x
stands for the probability distribution of (X
n
)
0 with X
0=x w.p.1. A is a closed set for (X
n
)
0.(ii) If is the supremum of the support of the distribution of C
1, then for all xA
(a)
for 12(b)
for 24(c)
for 24 under some additional smoothness condition on the distribution of C
1.(iii) The empirical distribution
converges weakly to
0, the delta measure at 0, w.p.1 for any initial distribution of X
0. 相似文献