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71.
Niemier MT Bernstein GH Csaba G Dingler A Hu XS Kurtz S Liu S Nahas J Porod W Siddiq M Varga E 《J Phys Condens Matter》2011,23(49):493202
Quoting the International Technology Roadmap for Semiconductors (ITRS) 2009 Emerging Research Devices section, 'Nanomagnetic logic (NML) has potential advantages relative to CMOS of being non-volatile, dense, low-power, and radiation-hard. Such magnetic elements are compatible with MRAM technology, which can provide input–output interfaces. Compatibility with MRAM also promises a natural integration of memory and logic. Nanomagnetic logic also appears to be scalable to the ultimate limit of using individual atomic spins.' This article reviews progress toward complete and reliable NML systems. More specifically, we (i) review experimental progress toward fundamental characteristics a device must possess if it is to be used in a digital system, (ii) consider how the NML design space may impact the system-level energy (especially when considering the clock needed to drive a computation), (iii) explain--using both the NML design space and a discussion of clocking as context—how reliable circuit operation may be achieved, (iv) highlight experimental efforts regarding CMOS friendly clock structures for NML systems, (v) explain how electrical I/O could be achieved, and (vi) conclude with a brief discussion of suitable architectures for this technology. Throughout the article, we attempt to identify important areas for future work. 相似文献
72.
Atomic recoil events on free surfaces orthogonal to two different anti-phase boundaries (APBs) and two grain boundaries (GBs) in Ni3Al are simulated using molecular dynamics methods. The threshold energy for sputtering, E sp, and adatom creation, E ad, are determined as a function of recoil direction. The study is relevant to FEG STEM (a scanning transmission electron microscope fitted with a field emission gun) experiments on preferential Al sputtering and/or enhancement of the Ni–Al ratio near boundaries. Surfaces intersected by {110} and {111} APBs have minimum E sp of 6.5?eV for an Al atom on the Ni–Al mixed (M) surface, which is close to the value of 6.0?eV for a perfect M surface. High values of E sp of an Al atom generally occur at a large angle to the surface normal and depend strongly on the detailed atomic configuration of the surface. The mean E sp, averaged over all recoil directions, reveals that APBs have a small effect on the threshold sputtering. However, the results for E ad imply that an electron beam could create more Al adatoms on surfaces intersected by APBs than on those without. The equilibrium, minimum energy structures for a (001) surface intersected by either Σ5[001](210) or Σ25[001](340) symmetric tilt grain boundaries are computed. E sp for surface Al atoms near these GBs increases monotonically with increasing recoil angle to the surface normal, with a minimum value, which is only about 1?eV different from that obtained for a perfect surface. Temperature up to 300?K has no effect on this result. It is concluded that the experimental observations of preferential sputtering are due to effects beyond those for E sp studied here. Possible reasons for this are discussed. 相似文献
73.
Scanning tunneling microscopy (STM) experiments reveal that Co growth on Ag(1 1 0), at coverages of Co < 1 ML and low substrate temperatures (150 K), involves a concomitant insertion of Co into the top Ag layer and exchange of Ag out onto the surface. At 300 K, coverages of Co > 1 ML gives rise to a 3D nanocluster growth on the surface, with the clusters covered by Ag. Depending slightly on coverage, the clusters have a typical diameter of 3 nm and a height of 0.4 nm. Upon annealing to 500 K, major changes are observed in the morphology of the surface. STM and AES show that there is a reduction of the number of Co islands on the surface, partly due to subsurface Co cluster migration and partly due to sintering into larger clusters. 相似文献
74.
Thomas G Kurtz 《Journal of Functional Analysis》1973,12(1):55-67
Let U(t) and S(t) be strongly continuous contraction semigroups on a Banach space L with infinitesimal operators A and B, respectively. Suppose the closure of A + αB generates a semigroup Tα(t). The behavior of Tα(t) as α goes to infinity is examined. In particular, suppose S(t) converges strongly to P. If the closure of PA generates a semigroup T(t) on (P), then Tα(t) goes to T(t) on (P). If PA = 0 and if BVf = ?f for fε(P), conditions are given that imply Tα(αt) converges on (P) to a semigroup generated by the closure of PAVA.The results are used to obtain new and known limit theorems for random evolutions, which in turn give approximation theorems for diffusion processes. 相似文献
75.
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77.
David E. Portlock Anil C. Ghosh William E. Schwarzel Richard R. Kurtz Eliahu Boger Haldean C. Dalzell Raj K. Razdan 《Journal of heterocyclic chemistry》1976,13(4):781-788
Novel cyclol derivatives (Table 1, 15, 16 ) similar in structure to the peptide portion of ergocornine were synthesized. Detailed experimental procedures are given for the preparation of the cis- 13a and the unknown trans- 14a cyclol esters. 相似文献
78.
Nufer S Marinopoulos AG Gemming T Elsässer C Kurtz W Köstlmeier S Rühle M 《Physical review letters》2001,86(22):5066-5069
Transmission electron microscopy (TEM) and local density functional theory (LDFT) are combined to analyze the microscopic structure of the rhombohedral twin interface in alpha-Al2O3. LDFT provides interfacial energetics and atomic and electronic structures for three competing models. With high-resolution TEM the atomic structure at the interface is imaged quantitatively along two orthogonal zone axes. Electron energy loss spectroscopy in TEM with nanoscale spatial resolution yields the interfacial electronic structure. Both experiments confirm the theoretically preferred model quantitatively. 相似文献
79.
J.C Kurtz 《Journal of Differential Equations》1983,49(1):105-123
Variational methods are used in a weighted Sobolev space to prove the existence of solutions for a certain class of singular nonlinear ordinary differential equations. 相似文献
80.
The Fermi surface of tetragonally distorted fcc Co films grown on Cu(001) has been investigated with first-principles calculations and compared with an experimental determination using angle-resolved photoemission. The angular distributions for hnu=21-45 eV are dominated by the structure of the final states rather than by the shape of the Fermi surface. Theoretical estimates of the photoemission matrix elements support this observation. This suggests that photoemission can have limitations in mapping Fermi surfaces, especially for materials that exhibit flat, closely spaced valence bands. 相似文献