全文获取类型
收费全文 | 260篇 |
免费 | 0篇 |
国内免费 | 4篇 |
专业分类
化学 | 136篇 |
晶体学 | 1篇 |
力学 | 10篇 |
数学 | 42篇 |
物理学 | 48篇 |
无线电 | 27篇 |
出版年
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 5篇 |
2016年 | 3篇 |
2014年 | 3篇 |
2013年 | 8篇 |
2012年 | 3篇 |
2011年 | 11篇 |
2010年 | 9篇 |
2009年 | 7篇 |
2008年 | 7篇 |
2007年 | 13篇 |
2006年 | 13篇 |
2005年 | 9篇 |
2004年 | 6篇 |
2003年 | 15篇 |
2002年 | 10篇 |
2001年 | 7篇 |
2000年 | 5篇 |
1999年 | 3篇 |
1998年 | 6篇 |
1997年 | 7篇 |
1996年 | 6篇 |
1995年 | 7篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 7篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1979年 | 3篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 5篇 |
1972年 | 2篇 |
1971年 | 8篇 |
1970年 | 2篇 |
1967年 | 2篇 |
1966年 | 1篇 |
1924年 | 2篇 |
1923年 | 2篇 |
排序方式: 共有264条查询结果,搜索用时 31 毫秒
211.
We consider a code to be a subset of the vertex set of a Hamming graph. In this setting a neighbour of the code is a vertex which differs in exactly one entry from some codeword. This paper examines codes with the property that some group of automorphisms acts transitively on the set of neighbours of the code. We call these codes neighbour transitive. We obtain sufficient conditions for a neighbour transitive group to fix the code setwise. Moreover, we construct an infinite family of neighbour transitive codes, with minimum distance δ = 4, where this is not the case. That is to say, knowledge of even the complete set of code neighbours does not determine the code. 相似文献
212.
Frederic G. Kreys Louis J. Gillespie und Shinroku Mitsukuri 《Fresenius' Journal of Analytical Chemistry》1923,62(3-4):139-140
Ohne Zusammenfassung 相似文献
213.
Crespo A. Bellot M.M. Chabak K.D. Gillespie J.K. Jessen G.H. Miller V. Trejo M. Via G.D. Walker D.E. Winningham B.W. Smith H.E. Cooper T.A. Gao X. Guo S. 《Electron Device Letters, IEEE》2010,31(1):2-4
We report the first CW Ka-band radio-frequency (RF) power measurements at 35 GHz from a passivated Al0.82In0.18N/GaN high-electron mobility transistor on SiC with 9.8-nm-thin barrier. This device delivered a maximum of 5.8 W/mm with a power-added efficiency of 43.6% biased at VDS = 20 V and 10% IDSS when matched for power at CW. The device was grown by metal-organic chemical vapor deposition with 2.8-?m source-drain spacing and a gate length of 160 nm. An excellent ohmic contact was obtained with an Rc of 0.62 ?·mm. The maximum extrinsic transconductance was 354 mS/mm with an IDSS of 1197 mA/mm at a VGS of 0 V, an ft of 79 GHz, and an fmax of 113.8 GHz. 相似文献
214.
Fotouhi N Gillespie P Goodnow RA So SS Han Y Babiss LE 《Combinatorial chemistry & high throughput screening》2006,9(2):95-102
The process of Drug Discovery is a complex and high risk endeavor that requires focused attention on experimental hypotheses, the application of diverse sets of technologies and data to facilitate high quality decision-making. All is aimed at enhancing the quality of the chemical development candidate(s) through clinical evaluation and into the market. In support of the lead generation and optimization phases of this endeavor, high throughput technologies such as combinatorial/high throughput synthesis and high throughput and ultra-high throughput screening, have allowed the rapid analysis and generation of large number of compounds and data. Today, for every analog synthesized 100 or more data points can be collected and captured in various centralized databases. The analysis of thousands of compounds can very quickly become a daunting task. In this article we present the process we have developed for both analyzing and prioritizing large sets of data starting from diversity and focused uHTS in support of lead generation and secondary screens supporting lead optimization. We will describe how we use informatics and computational chemistry to focus our efforts on asking relevant questions about the desired attributes of a specific library, and subsequently in guiding the generation of more information-rich sets of analogs in support of both processes. 相似文献
215.
A rapid and selective HPLC method using monolithic columns was developed for the separation and quantification of the principal amphetamines in ecstasy tablets. Three monolithic (Chromolith RP18e) columns of different lengths (25, 50 and 100 mm) were assessed. Validation studies including linearity, selectivity, precision, accuracy and limit of detection and quantification were carried out using the Chromolith SpeedROD, RP-18e, 50 mm x 4.6 mm column. Column backpressure and van Deemter plots demonstrated that monolithic columns provide higher efficiency at higher flow rates when compared to particulate columns without the loss of peak resolution. Application of the monolithic column to a large number of ecstasy tablets seized in Ireland ensured its suitability for the routine analysis of ecstasy tablets. 相似文献
216.
The tau-leaping method of simulating the stochastic time evolution of a well-stirred chemically reacting system uses a Poisson approximation to take time steps that leap over many reaction events. Theory implies that tau leaping should be accurate so long as no propensity function changes its value "significantly" during any time step tau. Presented here is an improved procedure for estimating the largest value for tau that is consistent with this condition. This new tau-selection procedure is more accurate, easier to code, and faster to execute than the currently used procedure. The speedup in execution will be especially pronounced in systems that have many reaction channels. 相似文献
217.
Gillespie CS 《The Journal of chemical physics》2012,136(1):014101
In recent years, computer simulations have become increasingly useful when trying to understand the complex dynamics of biochemical networks, particularly in stochastic systems. In such situations stochastic simulation is vital in gaining an understanding of the inherent stochasticity present, as these models are rarely analytically tractable. However, a stochastic approach can be computationally prohibitive for many models. A number of approximations have been proposed that aim to speed up stochastic simulations. However, the majority of these approaches are fundamentally serial in terms of central processing unit (CPU) usage. In this paper, we propose a novel simulation algorithm that utilises the potential of multi-core machines. This algorithm partitions the model into smaller sub-models. These sub-models are then simulated, in parallel, on separate CPUs. We demonstrate that this method is accurate and can speed-up the simulation by a factor proportional to the number of processors available. 相似文献
218.
219.
The low temperature specific heat of a series of superconducting Pd-H alloys has been measured; broad yet very pronounced peaks whose widths are a function of hydrogen concentration are observed. An interesting scaling feature and a theoretical fitting of the data are discussed. A few results of some associated electrical resistance measurements are mentioned, and the possible role of Fe impurities in suppressing superconductivity in PdH alloys is considered. 相似文献
220.