全文获取类型
收费全文 | 6284篇 |
免费 | 976篇 |
国内免费 | 184篇 |
专业分类
化学 | 378篇 |
晶体学 | 18篇 |
力学 | 306篇 |
综合类 | 85篇 |
数学 | 2078篇 |
物理学 | 1470篇 |
无线电 | 3109篇 |
出版年
2025年 | 32篇 |
2024年 | 112篇 |
2023年 | 121篇 |
2022年 | 129篇 |
2021年 | 164篇 |
2020年 | 200篇 |
2019年 | 196篇 |
2018年 | 146篇 |
2017年 | 203篇 |
2016年 | 219篇 |
2015年 | 220篇 |
2014年 | 369篇 |
2013年 | 461篇 |
2012年 | 452篇 |
2011年 | 425篇 |
2010年 | 336篇 |
2009年 | 367篇 |
2008年 | 408篇 |
2007年 | 393篇 |
2006年 | 316篇 |
2005年 | 263篇 |
2004年 | 271篇 |
2003年 | 222篇 |
2002年 | 206篇 |
2001年 | 153篇 |
2000年 | 138篇 |
1999年 | 120篇 |
1998年 | 112篇 |
1997年 | 99篇 |
1996年 | 100篇 |
1995年 | 79篇 |
1994年 | 57篇 |
1993年 | 49篇 |
1992年 | 42篇 |
1991年 | 30篇 |
1990年 | 35篇 |
1989年 | 28篇 |
1988年 | 14篇 |
1987年 | 15篇 |
1986年 | 18篇 |
1985年 | 20篇 |
1984年 | 13篇 |
1983年 | 13篇 |
1982年 | 17篇 |
1981年 | 7篇 |
1980年 | 10篇 |
1979年 | 14篇 |
1978年 | 10篇 |
1977年 | 3篇 |
1976年 | 5篇 |
排序方式: 共有7444条查询结果,搜索用时 15 毫秒
1.
Multi-valued and universal binary neurons (MVN and UBN) are the neural processing elements with the complex-valued weights and high functionality. It is possible to implement an arbitrary mapping described by partially defined multiple-valued function on the single MVN. An arbitrary mapping described by partially defined or fully defined Boolean function, which can be non-threshold, may be implemented on the single UBN. The quickly converging learning algorithms exist for both types of neurons. Such features of the MVN and UBN may be used for solving the different problems. One of the most successful applications of the MVN and UBN is their usage as basic neurons in the Cellular Neural Networks (CNN). It opens the new effective opportunities in nonlinear image filtering and its applications to noise reduction, edge detection and solving of the super resolution problem. A number of experimental results are presented to illustrate the performance of the proposed algorithms.An erratum to this article can be found at 相似文献
2.
Belting, a vocal technique typically cultivated in musical theatre singing, differs timbrally from operatic singing in many interesting respects. The underlying phonatory differences have not been previously investigated in detail. Yet, belting is frequently associated with disturbances of voice function. Articulatory and phonatory characteristics are investigated in a female subject who is a professional singer (co-author JL) trained in both the operatic and belting styles and in an intermediate vocal technique (“mixed”). This article presents data obtained from this subject by video-fiberoptic observation of the pharynx, inverse filtering of airflow, and measurement of subglottal pressure. The results reveal that belting was characterized by very high subglottal pressures and sound levels, and apparently also by a comparatively high degree of glottal adduction. Comparisons with other investigations of related aspects of belting and operatic singing support the assumption that the data obtained from our subject are representative for these vocal techniques. 相似文献
3.
4.
数字图像三点中值去隔行技术研究 总被引:1,自引:1,他引:0
对传统三点中值去隔行算法进行改进,采用同步更新迭代的方法,提高了图像的画面质量.实验证明,该算法不仅降低了时间复杂度,保护图像边缘,而且明显改善了噪声滤波效果. 相似文献
5.
A mathematical representation is given of the processing performed by the peripheral nervous cells of the human visual system. This representation consists essentially of a set of shift-variant convolutions, implying non-uniform resolutions in both the space and frequency domains. A remarkable property of such “convolutions” is the form-invariance of their outputs with respect to (size) linear scalings of the inputs. It is shown that this latter property is a necessary support of the hypothesis according to which the visual system translates linear scalings of the (retinal) inputs into shifts of the (cortical) outputs. 相似文献
6.
7.
8.
9.
张正鸿 《电子信息对抗技术》2008,23(2):26-30,69
由雷达发射、接收系统导致的信号幅度、相位失真以及由目标径向速度导致的目标多普勒频率是影响脉冲压缩性能的三个主要因素。本文从理论上分析了这三个因素影响脉冲压缩性能的算法原理,通过仿真验证了它们的实际影响效果,对仿真中的情况进行解释说明,对相应指标要求进行了分析,并对在影响脉冲压缩性能的因素存在下的信号处理方法提出了实际的建议。 相似文献
10.
邵春玉 《宁波大学学报(理工版)》1995,(3)
研究在定时有替换截尾试验下,指数模型点估计的验前参数的确定方法,讨论了验前参数的有关性质并给出了确定验前参数取值适合域的方法.最后用例子说明Bayes估计“优于”经典估计. 相似文献