全文获取类型
收费全文 | 79786篇 |
免费 | 7998篇 |
国内免费 | 4182篇 |
专业分类
电工技术 | 5295篇 |
技术理论 | 7篇 |
综合类 | 5895篇 |
化学工业 | 12990篇 |
金属工艺 | 4704篇 |
机械仪表 | 4993篇 |
建筑科学 | 5890篇 |
矿业工程 | 2471篇 |
能源动力 | 2422篇 |
轻工业 | 6321篇 |
水利工程 | 1512篇 |
石油天然气 | 4267篇 |
武器工业 | 921篇 |
无线电 | 9316篇 |
一般工业技术 | 9547篇 |
冶金工业 | 3333篇 |
原子能技术 | 1191篇 |
自动化技术 | 10891篇 |
出版年
2024年 | 483篇 |
2023年 | 1624篇 |
2022年 | 3039篇 |
2021年 | 4222篇 |
2020年 | 3060篇 |
2019年 | 2479篇 |
2018年 | 2680篇 |
2017年 | 3005篇 |
2016年 | 2630篇 |
2015年 | 3690篇 |
2014年 | 4474篇 |
2013年 | 5228篇 |
2012年 | 5673篇 |
2011年 | 6008篇 |
2010年 | 5195篇 |
2009年 | 4938篇 |
2008年 | 4763篇 |
2007年 | 4341篇 |
2006年 | 4013篇 |
2005年 | 3432篇 |
2004年 | 2404篇 |
2003年 | 2035篇 |
2002年 | 2075篇 |
2001年 | 1803篇 |
2000年 | 1528篇 |
1999年 | 1396篇 |
1998年 | 1090篇 |
1997年 | 922篇 |
1996年 | 850篇 |
1995年 | 649篇 |
1994年 | 549篇 |
1993年 | 372篇 |
1992年 | 285篇 |
1991年 | 225篇 |
1990年 | 185篇 |
1989年 | 151篇 |
1988年 | 119篇 |
1987年 | 68篇 |
1986年 | 75篇 |
1985年 | 37篇 |
1984年 | 31篇 |
1983年 | 29篇 |
1982年 | 27篇 |
1981年 | 17篇 |
1980年 | 19篇 |
1979年 | 12篇 |
1976年 | 6篇 |
1970年 | 2篇 |
1959年 | 9篇 |
1951年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
The effect of light absorption by sample in the analysis of Makerfringe data for estimating a second-order nonlinear coefficient hasbeen studied experimentally. Two theories, one by Jerphagnon andKurtz that neglects the absorption effect and one by Herman and Haydenthat takes into account the absorption effect, were compared with theexperimental results. It was found that Jerphagnon and Kurtz'sformula was unable to predict correctly not only the magnitude but alsothe incident angle dependence or the sample thickness dependence of thesecond harmonic signal generated by the sample with strong absorption, whereas the theory by Herman and Hayden was able to make thosepredictions fairly well. It was also found that the error in theestimated nonlinear coefficient when one uses Jerphagnon and Kurtz'sformula could be as large as 2-4 times the true value, depending onsample thickness. 相似文献
93.
A study of a new data association and track initiation method with normalized distance squared ordering 总被引:1,自引:0,他引:1
Seung-Woo Kim Young-Taek Lim Taek-Lyul Song 《International Journal of Control, Automation and Systems》2011,9(5):815-822
In an underwater environment, measurements regarding true targets and false targets (clutter) can be made. Therefore, a suitable
data association method to exactly detect and track a target and an efficient track initiation method for judging tracks formed
by the target should be selected in this environment. This paper attempts to propose a new data association method and track
initiation method to detect and track targets more effectively. Also, the performance of the new method is tested in a series
of Monte Carlo simulation runs and is compared with the existing data association and track initiation methods in a cluttered
environment. 相似文献
94.
We present a non-intrusive molecular dye based method, i.e., laser-induced fluorescence photobleaching anemometer (LIFPA),
to significantly increase temporal resolution (TR) for velocity measurement of fast transient electrokinetic flows. To our
knowledge, the TR has been for the first time achieved to 5–10 μs, about 100 times better than that published from state-of-the-art
micro particle image velocimetry (μPIV), which is currently the most widely used velocimetry in the microfluidics community.
The new method provides us with new opportunities to study experimentally the fundamental phenomena of unsteady electrokinetics
(EK) and to validate relevant theoretical models. One application of the new method is demonstrated by measuring the rise
time of DC electroosmotic flows (EOFs) in a microcapillary of 10 μm in diameter. 相似文献
95.
为了提高RSA密码算法在密码芯片上的实现性能,基于SOPC技术设计了一款RSA密码芯片,完成了NIOS Ⅱ的软硬件协同设计.该硬件系统由处理器、存储模块和自定义指令3部分组成,其关键的模乘模块采用改进的模乘算法和交叉存取设计方案设计实现,显著提高了系统性能.整体设计在ALTERA的CYCLONEⅡ器件上进行了验证与测试,并进行了逻辑综合及布局布线.与传统的RSA密码芯片设计相比,该芯片系统灵活性高,资源占用少. 相似文献
96.
Xin Ma Xinlong Xu Zheng Zheng Kun Wang Yalin Su Jiangfeng Fan Rui Zhang Lusheng Song Zhiyou Wang Jinsong Zhu 《Sensors and actuators. A, Physical》2010,157(1):9-14
An electro-optically modulated intensity interrogation method based on tunable waveguide coupled surface plasmon resonance sensors has been proposed. It has been theoretically and experimentally demonstrated that the proposed scheme can enable sensitive measurement of measurand variations. By modulating the refractive index in the waveguide layer, this interrogation method yields modulated signal whose amplitude is related to measurand's refractive index. This amplitude modulated signal offers a higher signal to noise ratio and eliminates additive noise in the sensor system. A preliminary investigation using saline buffers with different NaCl concentrations shows a resolution of 2.3 × 10?6 refractive index unit by our approach. Resolution can be controlled by the amplitude of the applied modulation voltage and can be further enhanced by optimizing the device structure or improving the electro-optical (E-O) coefficient of the E-O material. This approach is simple, stable, and promising for low-cost or multi-channel SPR biosensor applications. 相似文献
97.
Song Hak Kim Chun Keun Jang Sung Hoon Jeong Jae Yun Jaung 《Journal of the Society for Information Display》2010,18(11):994-1009
Abstract— Even though dyes have a fine resolution and good chromaticities, they are not widely used as coloring materials for color filters (CFs) due to their low thermal stability and chemical resistance. A series of azo‐dye derivatives, which consist of two cross‐linkable acrylate or methacrylate groups to improve thermal and chemical properties, have been synthesized and used to fabricate color filters. The spectral properties and chemical/thermal stabilities of the fabricated CFs were investigated by comparing dye‐based CFs, without a complicated dispersion process, but with pigment‐based CFs using dispersed pigment. Also, more properties including the development test and surface morphologies lithographic properties were studied. The synthesized azo dyes were characterized by elemental analysis, UV‐visible spectra, IR, mass, and 1H‐NMR spectra. 相似文献
98.
99.
100.
为了降低应用于突发事件监测的无线传感器网络的能量消耗,设计实现了一种基于事件驱动的动态免疫分簇路由算法。将生物免疫系统的工作机制应用到无线传感器网络事件驱动的动态分簇算法中,事件作为抗原,传感器节点作为抗体,抗体对抗原有记忆保存的功能,使得相似的抗原再次出现时对事件及时响应。相似事件再次发生且传感器节点符合能量要求时,可以直接调用抗体中的记忆,对事件进行快速建簇,节省了簇的建立过程所消耗的大量能量,增加了网络的数据传输量,延长了网络的生命周期。仿真结果表明,生物免疫机制的学习记忆特性可以有效提高事件驱动的动态分簇算法的网络性能。 相似文献