全文获取类型
收费全文 | 167篇 |
免费 | 2篇 |
专业分类
化学 | 81篇 |
晶体学 | 4篇 |
力学 | 10篇 |
数学 | 8篇 |
物理学 | 66篇 |
出版年
2022年 | 1篇 |
2021年 | 5篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2015年 | 2篇 |
2014年 | 7篇 |
2013年 | 9篇 |
2012年 | 5篇 |
2011年 | 8篇 |
2010年 | 2篇 |
2009年 | 4篇 |
2008年 | 8篇 |
2007年 | 9篇 |
2006年 | 4篇 |
2005年 | 5篇 |
2004年 | 5篇 |
2002年 | 5篇 |
2001年 | 3篇 |
2000年 | 6篇 |
1999年 | 5篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1984年 | 3篇 |
1983年 | 8篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1937年 | 1篇 |
1936年 | 2篇 |
1932年 | 1篇 |
排序方式: 共有169条查询结果,搜索用时 15 毫秒
101.
This paper addresses the problem of scheduling jobs in a single machine with sequence dependent setup times in order to minimize
the total tardiness with respect to job due dates. We propose variants of the GRASP metaheuristic that incorporate memory-based
mechanisms for solving this problem. There are two mechanisms proposed in the literature that utilize a long-term memory composed
of an elite set of high quality and sufficiently distant solutions. The first mechanism consists of extracting attributes
from the elite solutions in order to influence the construction of an initial solution. The second one makes use of path relinking
to connect a GRASP local minimum with a solution of the elite set, and also to connect solutions from the elite set. Reactive
GRASP, which probabilistically determines the degree of randomness in the GRASP construction throughout the iterations, is
also investigated. Computational tests for instances involving up to 150 jobs are reported, and the proposed method is compared
with heuristic and exact methods from the literature. 相似文献
102.
N. Andreeva D. Bassi F. Cappa P.S. Cocconcelli F. Parmigiani G. Ferrini 《Micron (Oxford, England : 1993)》2010,41(8):945-952
In this work we report on the measurement of the Young modulus of the external surface of Clostridium tyrobutyricum spores in air with an atomic force microscope. The Young modulus can be reliably measured despite the strong tip-spore adhesion forces and the need to immobilize the spores due to their slipping on most substrates. Moreover, we investigate the disturbing factors and consider some practical aspects that influence the measurements of elastic properties of biological objects with the atomic force microscopy indentation techniques. 相似文献
103.
Zepparelli F. Mezzanotte P. Alimenti F. Roselli L. Sorrentino R. Tartarini G. Bassi P. 《Optical and Quantum Electronics》1999,31(9-10):827-841
Continous advances in material technology, in the field of integrated optics and optoelectronics, allow the realization of devices with geometries more and more compact and complex. Because of this trend, there is a parallel need for accurate fully numerical CAD tools. Among new ones, the FDTD method, already widely and successfully used for the characterization of microwave and millimeter-wave devices, is emerging in optics community because of its accuracy and versatility. However, in spite of the tremendous increase in computing power, the applicability of the method is still limited by the typical dimensions of optical structures. To overcome these limitations a specialized version of the FDTD algorithm for the rigorous analysis of 3D optical and optoelectronic devices is proposed and validated. This new technique is then used to characterize the optical behaviour of a MQW waveguide electroabsorption modulator. 相似文献
104.
105.
106.
Martina Costa Reis Yongqi Wang Adalberto Bono Maurizio Sacchi Bassi 《Journal of mathematical chemistry》2014,52(2):441-463
This work focuses on formulating constitutive models for the bulk and double layer regions of an electrochemical system based on the fundamentals of modern continuum thermodynamics. Particularly, the constitutive models proposed accounting for transport phenomena in electrochemical systems by emphasizing the possibility of cross-coupling between two or more phenomena. Upon deriving a set of thermodynamic restrictions from the Müller-Liu approach of the second law of thermodynamics and axioms of constitutive theory, non-equilibrium quantities are examined in detail, and constitutive answers of the bulk and double layer regions are discussed. Moreover, the conditions for the thermodynamic equilibrium are evaluated for each region as well as the occurrence of dissipative mechanisms. Besides offering a proper formulation for non-equilibrium electrochemical systems, the approach described in this work can be easily extended to more complex chemical systems. 相似文献
107.
We present a fast reconstruction method for fluorescence optical tomography with structured illumination. Our approach is based on the exploitation of the wavelet transform of the measurements acquired after wavelet-patterned illuminations. This method, validated on experimental data, enables us to significantly reduce the acquisition and computation times with respect to the classical scanning approach. Therefore, it could be particularly suited for in vivo applications. 相似文献
108.
Bassi A Swartling J D'Andrea C Pifferi A Torricelli A Cubeddu R 《Optics letters》2004,29(20):2405-2407
We describe an instrument for the time-resolved spectroscopy of turbid media that is based on supercontinuum generation in a photonic crystal fiber. The light injected into the sample consists of subpicosecond pulses that cover 550-1000 nm at 85 MHz at an average power of as much as 40 mW. A spectrometer coupled to a multianode photomultiplier tube is used to detect the light simultaneously in 16 wavelength channels, with a resolution of 5-20 nm/channel, depending on the grating. Time-correlated single-photon counting is used to produce time-dispersion curves, which one fits to the diffusion equation to determine absorption and reduced scattering coefficients. We tested the instrument by measuring the time-resolved diffuse reflectance of epoxy phantoms and by performing in vivo measurements on volunteers. The results were similar to those obtained with previous discrete wavelength systems, whereas the full spectrum (610-810 nm) acquisition time was as short as 1 s owing to the parallel acquisition. 相似文献
109.
We analyze the recently proposed mirror superposition experiment of Marshall, Simon, Penrose, and Bouwmeester, assuming that the mirror's dynamics contains a nonunitary term of the Lindblad-type proportional to -[q,[q,rho]], with q the position operator for the center of mass of the mirror, and rho the statistical operator. We derive an exact formula for the fringe visibility for this system. We discuss the consequences of our result for tests of environmental decoherence and of collapse models. In particular, we find that with the conventional parameters for the continuous spontaneous localization model of state vector collapse, maintenance of coherence is expected to within an accuracy of at least 1 part in 10(8). Increasing the apparatus coupling to environmental decoherence may lead to observable modifications of the fringe visibility, with time dependence given by our exact result. 相似文献
110.
A. Bailini A. Li Bassi V. Russo A. Baserga C.E. Bottani 《Applied Surface Science》2007,253(19):8130-8135
Nanostructured thin films synthesized by assembling atoms or clusters present a structure characterized by a modulation at the nanoscale and by a large effective area, which can be exploited for the tailoring of specific structural or electronic properties. These systems are appealing for functional applications, e.g. in sensing and catalysis. We have investigated the deposition of tungsten and tungsten oxide thin films with a wide range of morphologies by exploiting nanosecond pulsed laser deposition (PLD) in an inert background atmosphere (He, Ar and Kr). We show that the non-dimensional ratio of the target-to-substrate distance to the time integrated visible plume length, which depends on the gas mass and pressure and on the substrate position, permits to select morphologies ranging from a compact structure with a density similar to bulk, to a film with an open, low density foam-like mesostructure and a high fraction of voids. 相似文献