全文获取类型
收费全文 | 20872篇 |
免费 | 2865篇 |
国内免费 | 1795篇 |
专业分类
电工技术 | 1621篇 |
综合类 | 2132篇 |
化学工业 | 1709篇 |
金属工艺 | 1087篇 |
机械仪表 | 1254篇 |
建筑科学 | 2708篇 |
矿业工程 | 578篇 |
能源动力 | 801篇 |
轻工业 | 609篇 |
水利工程 | 570篇 |
石油天然气 | 1037篇 |
武器工业 | 568篇 |
无线电 | 2995篇 |
一般工业技术 | 3019篇 |
冶金工业 | 626篇 |
原子能技术 | 326篇 |
自动化技术 | 3892篇 |
出版年
2024年 | 100篇 |
2023年 | 320篇 |
2022年 | 592篇 |
2021年 | 710篇 |
2020年 | 820篇 |
2019年 | 695篇 |
2018年 | 714篇 |
2017年 | 820篇 |
2016年 | 906篇 |
2015年 | 934篇 |
2014年 | 1330篇 |
2013年 | 1459篇 |
2012年 | 1454篇 |
2011年 | 1639篇 |
2010年 | 1218篇 |
2009年 | 1249篇 |
2008年 | 1268篇 |
2007年 | 1456篇 |
2006年 | 1356篇 |
2005年 | 1128篇 |
2004年 | 948篇 |
2003年 | 728篇 |
2002年 | 623篇 |
2001年 | 515篇 |
2000年 | 457篇 |
1999年 | 354篇 |
1998年 | 334篇 |
1997年 | 291篇 |
1996年 | 216篇 |
1995年 | 174篇 |
1994年 | 158篇 |
1993年 | 96篇 |
1992年 | 88篇 |
1991年 | 75篇 |
1990年 | 65篇 |
1989年 | 50篇 |
1988年 | 35篇 |
1987年 | 30篇 |
1986年 | 14篇 |
1985年 | 14篇 |
1984年 | 11篇 |
1983年 | 9篇 |
1982年 | 15篇 |
1981年 | 6篇 |
1980年 | 14篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1966年 | 4篇 |
1963年 | 4篇 |
1959年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
102.
本文根据光传输理论导出介导消光系数,折射率与介质电磁参数,光波频率,电偶极子浓度及迁移率等的关系,分析了光激发与增加气敏介质的氧吸附的规律,结合实验说明气敏薄膜的光学变化机制。 相似文献
103.
陈希武 《中国计量学院学报》1992,(1)
本文提出并研制成补偿式光纤F-P干涉仪信号处理系统,提出了用来测量微小位移信号的三种方法及电路,即透射峰时间间隔测量法、光脉冲基波幅度测量法(精密整流法)、鉴相法。测试结果表明:时间间隔测量法,它的最大灵敏度达到0.26纳米/微秒;精密整流法,最大灵敏度为2.38纳米/伏特。 相似文献
104.
报道了一种新型高灵敏浸没型HgCdTe红外探测器的研制,获得了D^*=1.46×10^11cmHz^1/2W^-1,R=608V/W,λc(20%)-20μ,灵敏元面积A=0.12×0.12mm^2,和有效通光孔径ψ=6mm的浸没型器件。 相似文献
105.
In this paper we present a new radiosity algorithm, based on the notion of a well distributed ray set (WDRS). A WDRS is a set of rays, connecting mutually visible points and patches, that forms an approximate representation of the radiosity operator and the radiosity distribution. We propose an algorithm that constructs an optimal WDRS for a given accuracy and mesh. The construction is based on discrete importance sampling as in previously proposed stochastic radiosity algorithms, and on quasi Monte Carlo sampling. Quasi Monte Carlo sampling leads to faster convergence rates and the fact that the sampling is deterministic makes it possible to represent the well distributed ray set very efficiently in computer memory. Like previously proposed stochastic radiosity algorithms, the new algorithm is well suited for computing the radiance distribution in very complex diffuse scenes, when it is not feasible to explicitly compute and store form factors as in classical radiosity algorithms. Experiments show that the new algorithm is often more efficient than previously proposed Monte Carlo radiosity algorithms by half an order of magnitude and more. 相似文献
106.
Speed-up fractal image compression with a fuzzy classifier 总被引:4,自引:0,他引:4
This paper presents a fractal image compression scheme incorporated with a fuzzy classifier that is optimized by a genetic algorithm. The fractal image compression scheme requires to find matching range blocks to domain blocks from all the possible division of an image into subblocks. With suitable classification of the subblocks by a fuzzy classifier we can reduce the search time for this matching process so as to speedup the encoding process in the scheme. Implementation results show that by introducing three image classes and using fuzzy classifier optimized by a genetic algorithm the encoding process can be speedup by about 40% of an unclassified encoding system. 相似文献
107.
108.
A system-on-chip (SOC) usually consists of many memory cores with different sizes and functionality, and they typically represent a significant portion of the SOC and therefore dominate its yield. Diagnostics for yield enhancement of the memory cores thus is a very important issue. In this paper we present two data compression techniques that can be used to speed up the transmission of diagnostic data from the embedded RAM built-in self-test (BIST) circuit that has diagnostic support to the external tester. The proposed syndrome-accumulation approach compresses the faulty-cell address and March syndrome to about 28% of the original size on average under the March-17N diagnostic test algorithm. The key component of the compressor is a novel syndrome-accumulation circuit, which can be realized by a content-addressable memory. Experimental results show that the area overhead is about 0.9% for a 1Mb SRAM with 164 faults. A tree-based compression technique for word-oriented memories is also presented. By using a simplified Huffman coding scheme and partitioning each 256-bit Hamming syndrome into fixed-size symbols, the average compression ratio (size of original data to that of compressed data) is about 10, assuming 16-bit symbols. Also, the additional hardware to implement the tree-based compressor is very small. The proposed compression techniques effectively reduce the memory diagnosis time as well as the tester storage requirement. 相似文献
109.
本文指出一种地化学闭合模型的热中子瞬发活化伽马分析方法,它是地球化学测井的核心技术,标准谱的获得,基于标准谱的加权最小二乘解谱方法、灵敏度刻度及地球化学闭合模型是这一方法的关键环节。 相似文献
110.
研究分析在用压缩试验确定金属高温塑性流动方程时影响流动应力,应变值精度的主要因素即试样表面摩擦与变形温升,并提出了相应的的修正方法。 相似文献