全文获取类型
收费全文 | 403761篇 |
免费 | 88086篇 |
国内免费 | 57149篇 |
专业分类
电工技术 | 43627篇 |
技术理论 | 12篇 |
综合类 | 39833篇 |
化学工业 | 55891篇 |
金属工艺 | 37137篇 |
机械仪表 | 21690篇 |
建筑科学 | 29645篇 |
矿业工程 | 19396篇 |
能源动力 | 14671篇 |
轻工业 | 38302篇 |
水利工程 | 12514篇 |
石油天然气 | 22564篇 |
武器工业 | 6038篇 |
无线电 | 54712篇 |
一般工业技术 | 51862篇 |
冶金工业 | 15260篇 |
原子能技术 | 4065篇 |
自动化技术 | 81777篇 |
出版年
2024年 | 2719篇 |
2023年 | 7518篇 |
2022年 | 11314篇 |
2021年 | 14874篇 |
2020年 | 15669篇 |
2019年 | 22578篇 |
2018年 | 24557篇 |
2017年 | 26688篇 |
2016年 | 25864篇 |
2015年 | 28219篇 |
2014年 | 29782篇 |
2013年 | 30852篇 |
2012年 | 32966篇 |
2011年 | 30872篇 |
2010年 | 28130篇 |
2009年 | 24066篇 |
2008年 | 21994篇 |
2007年 | 20434篇 |
2006年 | 18418篇 |
2005年 | 15543篇 |
2004年 | 15680篇 |
2003年 | 13640篇 |
2002年 | 13924篇 |
2001年 | 12095篇 |
2000年 | 9221篇 |
1999年 | 8115篇 |
1998年 | 6276篇 |
1997年 | 5500篇 |
1996年 | 5156篇 |
1995年 | 4799篇 |
1994年 | 3873篇 |
1993年 | 3384篇 |
1992年 | 3212篇 |
1991年 | 2291篇 |
1990年 | 1812篇 |
1989年 | 1654篇 |
1988年 | 1234篇 |
1987年 | 445篇 |
1986年 | 362篇 |
1985年 | 258篇 |
1984年 | 180篇 |
1983年 | 138篇 |
1982年 | 193篇 |
1981年 | 181篇 |
1980年 | 150篇 |
1976年 | 225篇 |
1975年 | 206篇 |
1972年 | 235篇 |
1971年 | 127篇 |
1960年 | 205篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
Neural Processing Letters - This paper presents an approach to identify the unknown parameters of genetic regulatory network (GRN) in finite-time. The adaptive synchronization-based method is used... 相似文献
53.
Wireless Networks - In such mobile platforms as ships and aircraft, the detection and reconnaissance devices are near to the communication facilities. When working at the same time, they will... 相似文献
54.
Xueru Chen Yin Zhang Dashui Yuan Wu Huang Jing Ding Hui Wan Wei-Lin Dai Guofeng Guan 《材料科学技术学报》2021,71(12):211-220
Porous g-C3N4 nanosheets (PCN) were prepared by the nickel-assisted one-step thermal polymerization method.Hydrogen (H2) which was produced by the reaction between nickel (Ni) foam and ammonia (NH3) defined the structure and properties of PCN.During the formation of PCN,the participation of H2 not only enhanced the spacing between layers but also boosted the specific surface area that more active sites were exposed.Additionally,H2 promoted pores formation in the nanosheets,which was beneficial to the transfer of photons through lamellar structure and improved the absorption efficiency of visible light.Remarkably,the obtained PCN possessed better Cr(Ⅵ) photocatalytic reduction efficiency than pure g-C3N4.The reaction rate constant (k) of PCN (0.013 min-1) was approximately twice that of bare g-C3N4 (0.007 min-1).Furthermore,the effects of original pH and concentration of Cr(Ⅵ)-containing solution on removal efficiency of Cr(Ⅵ) were explored.A possible photocatalytic mechanism was proposed based on the experiments of radical scavengers and photoelectrochemical characterizations. 相似文献
55.
56.
退化特征提取是机械健康状态监测的重要组成部分,伴随旋转机械长时间连续运转,退化特征出现性能波动甚至下降,给退化特征提取和选择造成了困难.首先利用一个特征映射算法库对振动信号提取特征,并基于Kolnogorov-Smirnov (KS)检验和Benjamini-Yekutieli过程对原始特征集进行过滤,然后利用双目标优化遗传算法(Bi-objective Optimization Genetic Algorithm,BOGA)结合支持向量机分类器(Support Vector Classifier,SVC),在有监督的环境下搜索出最佳特征子集,其中BOGA设置了SVC分类精确度和特征子集维数两个目标函数,前者进行最大化,后者进行最小化.通过在液压泵退化状态数据集上进行实验和在凯斯西楚大学轴承数据集与FRESH_PCAa、ReliefF、JMIM三种方法进行对比,验证了该方法在退化状态识别上的较好性能. 相似文献
57.
Juan Ding Yong He Shenhe Fu Xiangsheng Xie Haowen Liang Jianying Zhou 《Journal of the Society for Information Display》2022,30(2):159-167
Illumination is essential for modern life as colorful world is perceived by human visionary system. Display technology has been developing rapidly in recent decades, and the basic principle is related to the way that the image is illuminated and light is emanated. Traditional illumination is provided by different types of light sources, and the display image is visible in large viewing space until the emanating light decays to zero. This work proposes and demonstrates a novel illumination scheme for a display in which the displaying images are visible only in specific spatial regions. The directional backlight ensures the image propagating to specific direction while imaging visibility can be controlled to terminate abruptly at certain distance from the display screen while exerting no influence to nearby regions. The working principle for such an illumination scheme is the use of the modulated coherent directional backlight through an axicon lens. It is shown that the illumination scheme can robustly deliver carried image information to the designated viewing region. This new illumination scheme has many advantages over conventional illumination, including its usage for personal display, very lower energy consumption, as well as minimizing light hazard pollution. 相似文献
58.
60.