全文获取类型
收费全文 | 4848篇 |
免费 | 354篇 |
国内免费 | 171篇 |
专业分类
电工技术 | 193篇 |
综合类 | 254篇 |
化学工业 | 736篇 |
金属工艺 | 224篇 |
机械仪表 | 209篇 |
建筑科学 | 336篇 |
矿业工程 | 141篇 |
能源动力 | 112篇 |
轻工业 | 255篇 |
水利工程 | 90篇 |
石油天然气 | 152篇 |
武器工业 | 46篇 |
无线电 | 686篇 |
一般工业技术 | 691篇 |
冶金工业 | 619篇 |
原子能技术 | 54篇 |
自动化技术 | 575篇 |
出版年
2024年 | 23篇 |
2023年 | 83篇 |
2022年 | 150篇 |
2021年 | 197篇 |
2020年 | 116篇 |
2019年 | 124篇 |
2018年 | 143篇 |
2017年 | 154篇 |
2016年 | 121篇 |
2015年 | 183篇 |
2014年 | 181篇 |
2013年 | 230篇 |
2012年 | 232篇 |
2011年 | 288篇 |
2010年 | 254篇 |
2009年 | 241篇 |
2008年 | 280篇 |
2007年 | 214篇 |
2006年 | 202篇 |
2005年 | 155篇 |
2004年 | 102篇 |
2003年 | 99篇 |
2002年 | 96篇 |
2001年 | 104篇 |
2000年 | 119篇 |
1999年 | 140篇 |
1998年 | 234篇 |
1997年 | 160篇 |
1996年 | 111篇 |
1995年 | 71篇 |
1994年 | 68篇 |
1993年 | 62篇 |
1992年 | 36篇 |
1991年 | 29篇 |
1990年 | 23篇 |
1989年 | 28篇 |
1988年 | 28篇 |
1987年 | 22篇 |
1986年 | 28篇 |
1985年 | 14篇 |
1984年 | 27篇 |
1983年 | 17篇 |
1982年 | 16篇 |
1981年 | 8篇 |
1980年 | 8篇 |
1979年 | 9篇 |
1978年 | 13篇 |
1977年 | 8篇 |
1976年 | 34篇 |
1956年 | 8篇 |
排序方式: 共有5373条查询结果,搜索用时 15 毫秒
61.
Kuo‐Chung Huang Yi‐Heng Chou Lang‐chin Lin Hoang Yan Lin Fu‐Hao Chen Ching‐Chiu Liao Yi‐Han Chen Kuen Lee Wan‐Hsuan Hsu 《Journal of the Society for Information Display》2013,21(6):263-270
The optimal viewing distance was proposed as a parameter for designing a parallax barrier 3D display. It can be designed based on simple geometric method and by considering the pitches of image display pixels and parallax barrier, or even including the aperture ratios of the image display pixels and parallax barrier. It can be analyzed by using ray tracing method. By considering the optical refraction index of the cover glass, the angular behavior of the system becomes more realistic; however, the geometric method is difficult to be used. We propose a revised method for estimating the view distance and angular behavior. In this paper, we have demonstrated a designated eye position (DEP) for each view and shown that multiple DEPs make a circular curve around the center of the display. We prove the new concept by comparing the optical ray tracing calculations and optical measurement. 相似文献
62.
乌江是目前我国按规划实施开发较为充分的典型河流之一.乌江水电开发环境保护工作见证了我国经济建设由注重经济效益向协调环境效益和社会效益实现可持续发展的转变,见证了我国水电开发环境保护工作逐步认识、探索实践与发展完善的过程.本文回顾了乌江水电开发环境保护工作的历程,介绍了乌江水电开发环境保护典型措施及工作经验,提出了当前水... 相似文献
63.
本系统分析建立在理论设计和实际应用的基础上总结的,其系统构成有很强的针对性,设计思想在其他行业中也可用到。本文比较详细的叙述了连铸系统的工艺流程;并且由于系统本身的扩展性较强,系统的适应性也比较强。 相似文献
64.
概率引导的随机采样一致性算法 总被引:3,自引:0,他引:3
为了提高随机采样一致性算法的计算效率,提出一种概率引导的随机采样一致性算法.根据采样模型在原始数据上的检验结果调整每个样本点的采样概率,使得正确样本和正确模型被采样的概率得到提高.在首次获得正确模型之后,样本采样与模型更新构成了一个正反馈环节,经过若干次迭代后,正确样本被采样的概率远超过错误样本被采样的概率.理论分析和实验数据表明,该算法收敛需要的迭代次数较少,有效地提高了随机采样一致性算法的效率. 相似文献
65.
熊浪 《电脑编程技巧与维护》2009,(24):87-88,111
阐述基于ASP.NET技术构建一个实现网上购物的图书电子商务网站,并详细分析了系统的功能需求,及主要功能模块的设计与实现方法。该系统将Web技术和数据库技术很好地融合在一起,使数据库成为Web的重要组成部分,实现了数据库技术和网络技术的有机结合。 相似文献
66.
Jenq‐Lang Wu 《Asian journal of control》2009,11(3):295-301
A controller design method is provided to simultaneously stabilize a collection of nonlinear control systems in canonical form. It is shown that, under a mild assumption, any collection of nonlinear systems in canonical form can be simultaneously stabilized by one continuous state feedback controller. A constructive universal formula is presented explicitly. An illustrative example is given to demonstrate the validity of the method. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society 相似文献
67.
In order to reveal the relationship between system time domain model parameters and system frequency response functions, new magnitude bounds of frequency response functions for nonlinear Volterra systems described by NARX model are established. The magnitude bound of the nth-order generalized frequency response function (GFRF) can be expressed as a simple n-degree polynomial function of the magnitude of the first order GFRF, whose coefficients are functions of the model parameters and frequency variables. Thus the system output spectrum can also be bounded by a polynomial function of the magnitude of the first order GFRF. These results demonstrate explicitly the analytical relationship between model parameters and system frequency response functions, and provide a significant insight into the magnitude based analysis and synthesis of nonlinear systems in the frequency domain. 相似文献
68.
Ting Wu Tianqun Lang Chao Zheng Wenlu Yan Yu Li Runqi Zhu Xin Huang Huae Xu Yaping Li Qi Yin 《Advanced functional materials》2023,33(7):2212109
The red blood cell membrane (RBCm) provides tight protection, lowers the immunogenicity, and prolongs the circulation time of drugs in vivo when acting as the coating of drug delivery systems. However, the cellular uptake and release of drugs are hindered by RBCm. Docetaxel (DTX) is the first-line medicine for treating triple-negative breast cancer (TNBC), but it induces tumor metastasis. To solve these dilemmas, in this study, the photosensitizer 1,1-dioctadecyl-3,3,3,3-tetramethylindotricarbocyanine iodide (DiR)-modified RBCm (DM) is prepared, which is coated onto a hybrid micelle consisting of the prodrugs of DTX and the anti-metastasis agent calcitriol (CTL), obtaining a nanoparticle, named HDC-DM. In a 4T1 tumor-bearing mouse model, after injecting HDC-DM, the intratumoral DTX and CTL concentrations are increased by 1.7 and 2.5 times compared with the free drug groups. After irradiating tumors with near-infrared laser, DiR elicits the photothermal effect, triggering the rupture of RBCm and drug release, promoting drug penetration in tumors, and inducing immunogenic cell death. The tumor growth inhibition rate is 77%, and the formation of lung metastases is reduced by 82%, with good biocompatibility. It is suggested that the combination of phototherapy, chemotherapy, and anti-metastatic therapy using HDC-DM is expected to be a powerful strategy for treating TNBC. 相似文献
69.
Tao Cheng Xuan-Li Yang Sheng Yang Lang Li Zhong-Ting Liu Jie Qu Chao-Fu Meng Xiang-Chun Li Yi-Zhou Zhang Wen-Yong Lai 《Advanced functional materials》2023,33(5):2210997
Flexible transparent supercapacitors (FTSs) have aroused considerable attention. Nonetheless, balancing energy storage capability and transparency remains challenging. Herein, a new type of FTSs with both excellent energy storage and superior transparency is developed based on PEDOT:PSS/MXene/Ag grid ternary hybrid electrodes. The hybrid electrodes can synergistically utilize the high optoelectronic properties of Ag grids, the excellent capacitive performance of MXenes, and the superior chemical stability of PEDOT:PSS, thus, simultaneously demonstrating excellent optoelectronic properties (T: ≈89%, Rs: ≈39 Ω sq−1), high areal specific capacitance, superior mechanical softness, and excellent anti-oxidation capability. Due to the excellent comprehensive performances of the hybrid electrodes, the resulting FTSs exhibit both high optical transparency (≈71% and ≈60%) and large areal specific capacitance (≈3.7 and ≈12 mF cm−2) besides superior energy storage capacity (P: 200.93, E: 0.24 µWh cm−2). Notably, the FTSs show not only excellent energy storage but also exceptional sensing capability, viable for human activity recognition. This is the first time to achieve FTSs that combine high transparency, excellent energy storage and good sensing all-in-one, which make them stand out from conventional flexible supercapacitors and promising for next-generation smart flexible energy storage devices. 相似文献
70.
Sørland Kaia Ingerdatter Sunoqrot Mohammed R. S. Sandsmark Elise Langørgen Sverre Bertilsson Helena Trimble Christopher G. Lin Gigin Selnæs Kirsten M. Goa Pål E. Bathen Tone F. Elschot Mattijs 《Magma (New York, N.Y.)》2022,35(4):573-585
Magnetic Resonance Materials in Physics, Biology and Medicine - Signal intensity normalization is necessary to reduce heterogeneity in T2-weighted (T2W) magnetic resonance imaging (MRI) for... 相似文献