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排序方式: 共有198条查询结果,搜索用时 15 毫秒
191.
Letter: Stapedius reflex and speech features 总被引:1,自引:0,他引:1
192.
Anion radical of bacteriochlorophyll 总被引:6,自引:0,他引:6
J Fajer D C Borg A Forman D Dolphin R H Felton 《Journal of the American Chemical Society》1973,95(8):2739-2741
193.
M. Spiro R. Barloutaud A. Borg D. Denegri Y. Pons C. Comber K. Paler S.N. Tovey B. Chaurand B. Drevillon J.M. Gago R.A. Salmeron 《Nuclear Physics B》1977,125(2):162-188
We present experimental results and a partial-wave analysis of the low-mass systems produced in the reactions at 14.3 GeV/c. The main results concern the production mechanisms of the . We also extract the s-wave component of the system as a function of mass. 相似文献
194.
The inelastic α-scattering reaction at Eα = 120 MeV with an energy resolution of 90–150 keV has been used to investigate isoscalar strength distributions in 24, 26Mg, 28Si and 40Ca. For 24, 26Mg and 28Si the E2 strength between Ex = 14 and 27 MeV is strongly fragmented. In 40Ca the E2 strength is mainly concentrated near MeV, although here the onset of fragmentation can be observed. The sum rule strength for the different multipolarities was obtained by applying for each nucleus an L-dependent normalization procedure. In this way we observed in total in 24, 26Mg, 28Si and 40Ca for excitation energies up to 27 MeV an amount of (61+8?6), (50+9?8), (38+8?6) and (94 ± 14)%, respectively, of the isoscalar E2 energy weighted sum rule (EWSR) of which (36+7?5), (28+8?7), (24+7?5) and (74 ± 12)% was found between Ex = 14 and 27 MeV. In addition isoscalar E0, E3 and E4 strength was observed in this excitation energy region. A detailed comparison has been made between the isoscalar quadrupole strength distribution observed in the 24, 26Mg(α, α') reaction and the E2 strength excitation function obtained from radiative α-capture measurements. In the low excitation energy region coupled channel effects have been observed, especially for the excitation of the 3+ states. Moreover, a considerable percentage of the 1?ω isoscalar dipole and octupole strength has been observed for excitations below 14 MeV. 相似文献
195.
C.G. Wohl R. Barloutaud A. Borg D. Denegri Y. Pons M. Spiro K. Paler C. Comber S.N. Tovey B. Chaurand B. Drevillon J.M. Gago R.A. Salmeron 《Nuclear Physics B》1978,132(5):401-428
We present experimental results on a number of K?p reactions at 14.3 GeV/c that have three bodies in the final state. The final states are . Whenever, with one exception explained by the Zweig rule, there is a K? or a proton in the final state, there is a diffractive-like threshold enhancement in the mass spectrum of the two recoiling particles. These enhancements account for a large fraction of the events in all but the Λπ+π? final state, where they cannot occur, and which is dominated by resonance production. We find evidence for the Q1(1300) decaying into K?ω. 相似文献
196.
Peter Borg 《Graphs and Combinatorics》2011,27(6):785-797
For a family A{\mathcal{A}} and a set Z, denote
{A ? A \colon A ?Z 1 ?}{\{A \in \mathcal{A} \colon A \cap Z \neq \emptyset\}} by A(Z){\mathcal{A}(Z)}. For positive integers n and r, let Sn,r{\mathcal{S}_{n,r}} be the trivial compressed intersecting family
{A ? (c[n]r ) \colon 1 ? A}{\{A \in \big(\begin{subarray}{c}[n]\\r \end{subarray}\big) \colon 1 \in A\}}, where [n] : = {1, ?, n}{[n] := \{1, \ldots, n\}} and
(c[n]r ) : = {A ì [n] \colon |A| = r}{\big(\begin{subarray}{c}[n]\\r \end{subarray}\big) := \{A \subset [n] \colon |A| = r\}}. The following problem is considered: For r ≤ n/2, which sets Z í [n]{Z \subseteq [n]} have the property that |A(Z)| £ |Sn,r(Z)|{|\mathcal{A}(Z)| \leq |\mathcal{S}_{n,r}(Z)|} for any compressed intersecting family
A ì (c[n]r ){\mathcal{A}\subset \big(\begin{subarray}{c}[n]\\r \end{subarray}\big)}? (The answer for the case 1 ? Z{1 \in Z} is given by the Erdős–Ko–Rado Theorem.) We give a complete answer for the case |Z| ≥ r and a partial answer for the much harder case |Z| < r. This paper is motivated by the observation that certain interesting results in extremal set theory can be proved by answering
the question above for particular sets Z. Using our result for the special case when Z is the r-segment {2, ?, r+1}{\{2, \ldots, r+1\}}, we obtain new short proofs of two well-known Hilton–Milner theorems. At the other extreme end, by establishing that |A(Z)| £ |Sn,r(Z)|{|\mathcal{A}(Z)| \leq |\mathcal{S}_{n,r}(Z)|} when Z is a final segment, we provide a new short proof of a Holroyd–Talbot extension of the Erdős-Ko-Rado Theorem. 相似文献
197.
Optical properties and ultrafast electron dynamics in gold–silver alloy and core–shell nanoparticles
Silver and gold are the two most popular metals used for many nanoparticle applications, such as surface enhanced Raman scattering
or surface enhanced fluorescence, in which the local field enhancement associated with the excitation of the localized surface-plasmon–polariton
resonance (SPR) is exploited. Therefore, tunability of the SPR over a wide energy range is required. For this purpose we have
investigated core–shell nanoparticles composed of gold and silver with different shell thicknesses as well as the impact of
alloying on these nanoparticles due to a tempering process. The nanoparticles were prepared by subsequent deposition of Au
and Ag atoms or vice versa on quartz substrates followed by diffusion and nucleation. Their linear extinction spectra were
measured as a function of shell thickness and annealing temperature. It turned out that different gold shell thicknesses on
silver cores allow a tuning of the SPR position from 2.79 to 2.05 eV, but interestingly without a significant change on the
extinction amplitude. Heating of core–shell nanoparticles up to only 540 K leads to the formation of alloy nanoparticles,
accompanied by a back shift of the SPR to 2.60 eV. Calculations performed in quasi-static approximation describe the experimental
results quite well and prove the structural assignments of the samples. In additional experiments, we applied the well-established
persistent spectral hole burning technique to the alloy nanoparticles in order to determine the ultrafast dephasing time T
2. We obtained a dephasing time of T
2=(8.1±1.6) fs, in good agreement with the dephasing time of T
2,∞=8.9 fs, which is already included in the dielectric function of the bulk. 相似文献
198.
Nykter M Price ND Larjo A Aho T Kauffman SA Yli-Harja O Shmulevich I 《Physical review letters》2008,100(5):058702
Network structure strongly constrains the range of dynamic behaviors available to a complex system. These system dynamics can be classified based on their response to perturbations over time into two distinct regimes, ordered or chaotic, separated by a critical phase transition. Numerous studies have shown that the most complex dynamics arise near the critical regime. Here we use an information theoretic approach to study structure-dynamics relationships within a unified framework and show that these relationships are most diverse in the critical regime. 相似文献