全文获取类型
收费全文 | 166篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
化学 | 99篇 |
晶体学 | 1篇 |
力学 | 13篇 |
数学 | 11篇 |
物理学 | 45篇 |
出版年
2024年 | 1篇 |
2022年 | 2篇 |
2021年 | 3篇 |
2020年 | 5篇 |
2017年 | 1篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 4篇 |
2013年 | 13篇 |
2012年 | 5篇 |
2011年 | 8篇 |
2010年 | 9篇 |
2009年 | 27篇 |
2008年 | 4篇 |
2007年 | 10篇 |
2006年 | 7篇 |
2005年 | 3篇 |
2004年 | 8篇 |
2003年 | 2篇 |
2002年 | 6篇 |
2001年 | 10篇 |
2000年 | 8篇 |
1999年 | 5篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1993年 | 3篇 |
1991年 | 3篇 |
1988年 | 2篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1978年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有169条查询结果,搜索用时 15 毫秒
41.
Objectives: To examine the opportunities for and responsibilities of the public health community in bridging the gap between gene discovery and the application of genetic information to improve health and prevent disease. Methods: We developed genetics-related definitions for the core functions and essential services of public health. We combined these definitions with a visual model to create one possible 'blueprint' for integrating genomics into public health activities. Results: The proposed blueprint and accompanying examples illustrate the important role for genomics throughout public health research, policy and practice. Further refinement and implementation of this blueprint represents an ambitious public health leadership agenda. Conclusions: Opportunities for immediate action include strategic planning for the integration of genomics across programs, developing genomics competencies among health professionals, enhancing surveillance and epidemiologic capacity to aid evidence-based policy making, building partnerships and seeking input from stakeholders and incorporating information about genomics into health communications. Copyright 2001 S. Karger AG, Basel 相似文献
42.
43.
Helical molecular programming: folding of oligopyridine-dicarboxamides into molecular single helices
Berl V Huc I Khoury RG Lehn JM 《Chemistry (Weinheim an der Bergstrasse, Germany)》2001,7(13):2798-2809
Molecular strands composed of alternating 2,6-diaminopyridine and 2,6-pyridinedicarbonyl units have been designed to self-organize into single stranded helical structures upon forming intramolecular hydrogen bonds. Pentameric strands 11, 12, and 14, heptameric strands 1 and 20, and undecameric strand 15 have been synthesized using stepwise convergent strategies. Single helical conformations have been characterized in the solid state by single crystal X-ray diffraction analysis for four of these compounds. Helices from pentameric strands 12 and 14 extend over one turn, and helices from heptameric 20 and undecameric 15 species extend to one and a half and two and a half turns, respectively. Intramolecular hydrogen bonds are responsible for the strong bending of the strands. 1H NMR shifts both in polar and nonpolar organic solvents indicate intramolecular overlap between the peripheral aromatic groups. Thus, helical conformations also predominate in solution. Molecular stochastic dynamic simulations of strand folding starting from a high energy extended linear conformer show a rapid (600 ps at 300 K) conversion into a stable helical conformation. 相似文献
44.
The new ekpyrotic model is an alternative scenario of the early Universe which relies on a phase of slow contraction before the big bang. We calculate the 3-point and 4-point correlation functions of primordial density perturbations and find a generically large non-Gaussian signal, just below the current sensitivity level of cosmic microwave background experiments. This is in contrast with slow-roll inflation, which predicts negligible non-Gaussianity. The model is also distinguishable from alternative inflationary scenarios that can yield large non-Gaussianity, such as Dirac-Born-Infeld inflation and the simplest curvatonlike models, through the shape dependence of the correlation functions. Non-Gaussianity therefore provides a distinguishing and testable prediction of New Ekpyrotic Cosmology. 相似文献
45.
Multiphoton path entanglement is created without applying postselection, by manipulating the state of stimulated parametric down-conversion. A specific measurement on one of the two output spatial modes leads to the nonlocal bunching of the photons of the other mode, forming the desired multiphoton path entangled state. We present experimental results for the case of a heralded two-photon path entangled state and show how to extend this scheme to higher photon numbers. 相似文献
46.
We introduce a new phase-restricted algorithm for producing a heterogeneous correlation filter that permits new in-class members to be added without changing the phase of the filter. This heterogeneous correlation filter uses amplitude modulation both to enhance in-class cross correlations and to suppress selected out-of-class correlations. This new algorithm should substantially improve the performance of existing class-associative correlators and improve their operation. 相似文献
47.
We present a novel scenario where a scalar field acquires a mass which depends on the local matter density: the field is massive on Earth, where the density is high, but is essentially free in the solar system, where the density is low. All existing tests of gravity are satisfied. We predict that near-future satellite experiments could measure an effective Newton's constant in space different from that on Earth, as well as violations of the equivalence principle stronger than currently allowed by laboratory experiments. 相似文献
48.
Peter Benner Grece El Khoury Miloud Sadkane 《Numerical Linear Algebra with Applications》2014,21(5):645-665
A squared Smith type algorithm for solving large‐scale discrete‐time Stein equations is developed. The algorithm uses restarted Krylov spaces to compute approximations of the squared Smith iterations in low‐rank factored form. Fast convergence results when very few iterations of the alternating direction implicit method are applied to the Stein equation beforehand. The convergence of the algorithm is discussed and its performance is demonstrated by several test examples. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
49.
Hsiangkuo Yuan Andrew M. Fales Christopher G. Khoury Jesse Liu Tuan Vo‐Dinh 《Journal of Raman spectroscopy : JRS》2013,44(2):234-239
Plasmonic gold nanostars offer a new platform for surface‐enhanced Raman scattering (SERS). However, due to the presence of organic surfactant on the nanoparticles, SERS characterization and application of nanostar ensembles in solution have been challenging. Here, we applied our newly developed surfactant‐free nanostars for SERS characterization and application. The SERS enhancement factors (EF) of silver spheres, gold spheres and nanostars of similar sizes and concentration were compared. Under 785 nm excitation, nanostars and silver spheres have similar EF, and both are much stronger than gold spheres. Having plasmon matching the incident energy and multiple ‘hot spots’ on the branches bring forth strong SERS response without the need to aggregate. Intracellular detection of silica‐coated SERS‐encoded nanostars was also demonstrated in breast cancer cells. The non‐aggregated field enhancement makes the gold nanostar ensemble a promising agent for SERS bioapplications. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
50.
Ricardo Vinuesa Azad Noorani Adrián Lozano-Durán George K. El Khoury Philipp Schlatter Paul F. Fischer 《Journal of Turbulence》2013,14(10):677-706
Three-dimensional effects in turbulent duct flows, i.e., sidewall boundary layers and secondary motions, are studied by means of direct numerical simulation (DNS). The spectral element code Nek5000 is used to compute turbulent duct flows with aspect ratios 1–7 (at Reb, c = 2800, Reτ, c ? 180) and aspect ratio 1 (at Reb, c = 5600, Reτ, c ? 330), in streamwise-periodic boxes of length 25h. The total number of grid points ranges from 28 to 145 million, and the pressure gradient is adjusted iteratively in order to keep the same bulk Reynolds number in the centreplane with changing aspect ratio. Turbulence is initiated via a trip forcing active during the initial stages of the simulation, and the statistical convergence of the data is discussed both in terms of transient approach and averaging period. Spanwise variations in wall shear, mean-flow profiles, and turbulence statistics are analysed as a function of aspect ratio, and also compared with the spanwise-periodic channel (as idealisation of an infinite aspect ratio duct). The computations show good agreement with experimental measurements carried out in parallel at the Illinois Institute of Technology (IIT) in Chicago, and highlight the relevance of sidewall boundary layers and secondary vortices in the physics of the duct flow. The rich array of secondary vortices extending throughout the upper and lower walls of the duct, and their dependence on Reynolds number and aspect ratio, had not been reported in the literature before. 相似文献