全文获取类型
收费全文 | 2375篇 |
免费 | 764篇 |
国内免费 | 312篇 |
专业分类
化学 | 1088篇 |
晶体学 | 23篇 |
力学 | 137篇 |
综合类 | 40篇 |
数学 | 285篇 |
物理学 | 1878篇 |
出版年
2024年 | 7篇 |
2023年 | 39篇 |
2022年 | 70篇 |
2021年 | 60篇 |
2020年 | 63篇 |
2019年 | 62篇 |
2018年 | 81篇 |
2017年 | 104篇 |
2016年 | 104篇 |
2015年 | 112篇 |
2014年 | 211篇 |
2013年 | 159篇 |
2012年 | 210篇 |
2011年 | 244篇 |
2010年 | 189篇 |
2009年 | 180篇 |
2008年 | 185篇 |
2007年 | 200篇 |
2006年 | 150篇 |
2005年 | 162篇 |
2004年 | 115篇 |
2003年 | 117篇 |
2002年 | 71篇 |
2001年 | 76篇 |
2000年 | 55篇 |
1999年 | 45篇 |
1998年 | 50篇 |
1997年 | 57篇 |
1996年 | 48篇 |
1995年 | 45篇 |
1994年 | 29篇 |
1993年 | 18篇 |
1992年 | 27篇 |
1991年 | 15篇 |
1990年 | 16篇 |
1989年 | 12篇 |
1988年 | 13篇 |
1987年 | 14篇 |
1986年 | 9篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1983年 | 2篇 |
1982年 | 8篇 |
1981年 | 3篇 |
1969年 | 1篇 |
排序方式: 共有3451条查询结果,搜索用时 93 毫秒
11.
Curved Ferroelectric Liquid Crystal Matrix Displays Driven by Field-Sequential-Color and Active-Matrix Techniques 总被引:1,自引:0,他引:1
Hideo Fujikake Hiroto Sato Takeshi Murashige Yoshihide Fujisaki Taiichiro Kurita Tadahiro Furukawa Fumio Sato 《Optical Review》2006,13(1):14-19
This paper describes a curved field-sequential-color matrix display using fast-response ferroelectric liquid crystal. Black
matrix and transparent electrode patterns were formed on a thin plastic substrate by a transfer method from a glass substrate.
While a composite film of liquid crystal and micro-polymers of walls and fibers was formed between the flexible substrates
by printing, laminating and curing processes of a solution of monomers and liquid crystal, the mechanical stability was enhanced
by use of multi-functional monomers to form large display panels. The image pixels of the matrix panel were driven by an active
matrix scheme using an external switch transistor array at a frequency of 180 Hz for intermittent three-primary-color backlight
illumination. The flexible A4-paper-sized color display with 24 × 16 pixels and 60 Hz field frequency was demonstrated by
illuminating it with sequential three-primary-color lights from light-emitting diodes of the backlight. Our display system
is useful in various information displays because of its freedom of setting and location. 相似文献
12.
设{Xni:1≤i≤n,n≥1}为行间独立的B值r.v.阵列,g(z)是指数为1/p的正则变化函数,r>0,{ani 1≤t≤n,n≥1}为实数阵列,本文得到了使(?)成立的条件,推广并改进了Stout及Sung等的著名结论. 相似文献
13.
14.
15.
To satisfy the volatile nature of today’s markets, businesses require a significant reduction in product development lead times. Consequently, the ability to develop precise product sales forecasts is of fundamental importance to decision-makers. Over the years, many forecasting techniques of varying capabilities have been introduced. The precise extent of their influences, and the interactions between them, has never been fully clarified, although various forecasting factors have been explored in previous studies. Accordingly, this study adopts the Taguchi method to calibrate the controllable factors of a forecasting model. An L9(34) inner orthogonal array is constructed for the controllable factors of data period, horizon length, and number of observations required. An experimental design is then performed to establish the appropriate levels for each factor. At the same time, an L4(23) outer orthogonal array is used to consider the inherited parameters of forecasting method as the noise factors of Taguchi method simultaneously. An illustrated example, employing data from a power company, serves to demonstrate the thesis. The results show that the proposed model permits the construction of a highly efficient forecasting model through the suggested data collection method. 相似文献
16.
Humberto César Chaves Fernandes Arthur Rodrigo Barros da Rocha 《International Journal of Infrared and Millimeter Waves》2003,24(7):1171-1176
The use of photonic materials has been used in the theory of optical waves. The PBG (Photonic Band Gap) theory and material, was developed recently for optical frequencies and can be easily applied to millimeter waves, microwaves and planar antenna frequencies. The presence of photonic materials as substrate in antennas has some good characteristics such as, supression of light spontaneous emission and suppression of surface waves, allowing the application in planar antenna array. In this work an elaborate analysis using the full wave Transverse Transmission Line - TTL method, that provides efficient and concise results is applied to the planar antennas array with PBG substrate. 相似文献
17.
18.
Two types of optical current transducers (OCTs) have a bulk Faraday sensor inserted into the gap of an iron core and a porcelain
insulator with optical fiber. The sensor consists of Bi12SiO20 (BSO) single crystal, a polarizer, and an analyzer. The OCTs satisfied the target performance requirement for fault location
and metering and demonstrated maintained performance at some power utilities in Japan and the US. We have developed a fault
location system that immediately detects the fault current with the OCTs, there by locating the fault section. The OCT can
easily replace the existing support insulators for the disconnecting switch without any modifications to structure height
or bus-bar. For metering requiring 0.3% class accuracy, use of a BSO with right optical rotatory power combined with BSO with
left optical rotatory power results in a Faraday sensor with improved temperature characteristics. The OCT demonstrated 0.3%
class accuracy for metering described in the current transformer Specifications of IEEE C57–13, 1993. 相似文献
19.
20.
Kiyoshi Kurosawa 《Optical Review》1997,4(1):A38-A44
This paper describes development of the optical current transducers using flint glass fiber as the Faraday effect sensing
element. Excellent polarization properties of the fiber with low birefringence are described, and the design and test data
of a current transducer using the fiber manufactured for use in electric power facilities are reviewed. Experimental results
on flexible characteristics of a scheme with round trip light transmission in the fiber is also reported. 相似文献