全文获取类型
收费全文 | 3726篇 |
免费 | 305篇 |
国内免费 | 152篇 |
专业分类
电工技术 | 198篇 |
综合类 | 242篇 |
化学工业 | 598篇 |
金属工艺 | 255篇 |
机械仪表 | 230篇 |
建筑科学 | 345篇 |
矿业工程 | 130篇 |
能源动力 | 99篇 |
轻工业 | 223篇 |
水利工程 | 55篇 |
石油天然气 | 270篇 |
武器工业 | 21篇 |
无线电 | 411篇 |
一般工业技术 | 447篇 |
冶金工业 | 235篇 |
原子能技术 | 32篇 |
自动化技术 | 392篇 |
出版年
2024年 | 14篇 |
2023年 | 65篇 |
2022年 | 112篇 |
2021年 | 161篇 |
2020年 | 129篇 |
2019年 | 104篇 |
2018年 | 115篇 |
2017年 | 120篇 |
2016年 | 107篇 |
2015年 | 130篇 |
2014年 | 198篇 |
2013年 | 215篇 |
2012年 | 240篇 |
2011年 | 216篇 |
2010年 | 202篇 |
2009年 | 184篇 |
2008年 | 198篇 |
2007年 | 158篇 |
2006年 | 209篇 |
2005年 | 205篇 |
2004年 | 122篇 |
2003年 | 125篇 |
2002年 | 113篇 |
2001年 | 104篇 |
2000年 | 111篇 |
1999年 | 91篇 |
1998年 | 76篇 |
1997年 | 55篇 |
1996年 | 47篇 |
1995年 | 66篇 |
1994年 | 39篇 |
1993年 | 27篇 |
1992年 | 27篇 |
1991年 | 24篇 |
1990年 | 11篇 |
1989年 | 14篇 |
1988年 | 16篇 |
1987年 | 17篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有4183条查询结果,搜索用时 0 毫秒
71.
LIGA技术制作Fresnel波带片的研究 总被引:2,自引:0,他引:2
简要介绍了利用LIGA技术中同步辐射光刻、微电铸技术制作α粒子编码成像波带片的研究,讨论了编码波带片的结构和影响波带片的平面和层析分辨率的参数。根据实验要求设计和研制了一种α粒子编码成像波带片。 相似文献
72.
Yuhui He Ralph H. Scheicher Anton Grigoriev Rajeev Ahuja Shibing Long ZongLiang Huo Ming Liu 《Advanced functional materials》2011,21(14):2674-2679
The use of graphene electrodes with hydrogenated edges for solid‐state nanopore‐based DNA sequencing is proposed, and molecular dynamics simulations in conjunction with electronic transport calculations are performed to explore the potential merits of this idea. The results of the investigation show that, compared to the unhydrogenated system, edge‐hydrogenated graphene electrodes facilitate the temporary formation of H‐bonds with suitable atomic sites in the translocating DNA molecule. As a consequence, the average conductivity is drastically raised by about 3 orders of magnitude while exhibiting significantly reduced statistical variance. Furthermore, the effect of the distance between opposing electrodes is investigated and two regimes identified: for narrow electrode separation, the mere hindrance due to the presence of protruding hydrogen atoms in the nanopore is deemed more important, while for wider electrode separation, the formation of H‐bonds becomes the dominant effect. Based on these findings, it is concluded that hydrogenation of graphene electrode edges represents a promising approach to reduce the translocation speed of DNA through the nanopore and substantially improve the accuracy of the measurement process for whole‐genome sequencing. 相似文献
73.
Chin-Hui Lee Qiang Huo 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2000,88(8):1241-1269
Recent advances in automatic speech recognition are accomplished by designing a plug-in maximum a posteriori decision rule such that the forms of the acoustic and language model distributions are specified and the parameters of the assumed distributions are estimated from a collection of speech and language training corpora. Maximum-likelihood point estimation is by far the most prevailing training method. However, due to the problems of unknown speech distributions, sparse training data, high spectral and temporal variabilities in speech, and possible mismatch between training and testing conditions, a dynamic training strategy is needed. To cope with the changing speakers and speaking conditions in real operational conditions for high-performance speech recognition, such paradigms incorporate a small amount of speaker and environment specific adaptation data into the training process. Bayesian adaptive learning is an optimal way to combine prior knowledge in an existing collection of general models with a new set of condition-specific adaptation data. In this paper, the mathematical framework for Bayesian adaptation of acoustic and language model parameters is first described. Maximum a posteriori point estimation is then developed for hidden Markov models and a number of useful parameters densities commonly used in automatic speech recognition and natural language processing 相似文献
74.
Ran Huo Guangyu Bao Zixin He Xuan Li Zhenwei Ma Zhen Yang Roozbeh Moakhar Shuaibing Jiang Christopher Chung-Tze-Cheong Alexander Nottegar Changhong Cao Sara Mahshid Jianyu Li 《Advanced functional materials》2023,33(20):2213677
Emerging soft ionotronics better match the human body mechanically and electrically compared to conventional rigid electronics. They hold great potential for human-machine interfaces, wearable and implantable devices, and soft machines. Among various ionotronic devices, ionic junctions play critical roles in rectifying currents as electrical p–n junctions. Existing ionic junctions, however, are limited in electrical and mechanical performance, and are difficult to fabricate and degrade. Herein, the design, fabrication, and characterization of tough transient ionic junctions fabricated via 3D ionic microgel printing is reported. The 3D printing method demonstrates excellent printability and allows one to fabricate ionic junctions of various configurations with high fidelity. By combining ionic microgels, degradable networks, and highly charged biopolymers, the ionic junctions feature high stretchability (stretch limit 27), high fracture energy (>1000 Jm−2), excellent electrical performance (current rectification ratio >100), and transient stability (degrade in 1 week). A variety of ionotronic devices, including ionic diodes, ionic bipolar junction transistors, ionic full-wave rectifiers, and ionic touchpads are further demonstrated. This study merges ionotronics, 3D printing, and degradable hydrogels, and will motivate the future development of high-performance transient ionotronics. 相似文献
75.
Bing Zheng Yuchen Yue Jianling Ni Xucong Zhou Yongrui He Xiaoman Gui Han Shen Yanan Jing Jince Zhao Jianqi Zhang Yuan Zhang Jingxia Wang Lei Jiang Lijun Huo 《Advanced functional materials》2023,33(28):2300981
With the development of organic solar cells (OSCs), the high-performance and stable batch variance are becoming a new challenge for designing polymer donors. To obtain high photovoltaic performance, adopting polymers with high molecular weight as donors is an ordinary strategy. However, the high molecular weight need to subtly control the reaction time and state, inevitably caused batch-to-batch variations. Herein, a strategy of steric effect is applied to benzodifuran (BDF)-based polymer by introducing different positions of Cl atom, producing two polymers PBDFCl-1 and PBDFCl-2. The more twisted side chains conformation not only achieve the control of moderate molecular weight for PBDFCl-2, but also easily form molecular stacking through adopting BDF unit and maintain sufficient polymeric crystallinity. Due to the optimized stacking mode and good blend miscibility, PBDFCl-2-based device exhibitsa more elegant power conversion efficiency (PCE) of 17.00% compared to PBDFCl-1-based device. This is the highest efficiency record for BDF-based binary OSCs. Meanwhile, the PCE device variation of the different molecular weights for PBDFCl-2 is little, indicating the reduction of the batch variation. Therefore, smartly using steric effect of Cl atom in strong crystalline BDF unit can form efficient molecular stacking regulations and realize the coordination of high-performance and stable batch variance. 相似文献
76.
Rongjie Luo Qifei Guo Zihuan Tang Miaomiao Zhang Xingxing Li Biao Gao Xuming Zhang Kaifu Huo Yang Zheng 《Advanced functional materials》2023,33(48):2306115
The serious shuttle effect and sluggish reaction kinetics intrinsically handicap the practical application of Li-S batteries. Herein, a unique 3D hierarchically porous Mott–Schottky electrocatalyst composed of W2C quantum dots (QD) spatially confined in nitrogen-doped graphene microspheres (NGM) is proposed for regulating the kinetics of sulfur electrochemistry. Experimental and theoretical results disclose a spontaneous charge rearrangement and induce built-in electric field across the W2C QD/NGM heterojunction interface, contributing to reduced energy barrier for both polysulfides reduction and Li2S oxidation during entitle discharge/charge processes. Furthermore, the ultrasmall W2C QD with high electrocatalytic activity and superior conductivity can promote the conversion of S species, while the hierarchically porous microspheres assembled from wrinkled graphene nanosheets not only can efficiently inhibit the polysulfides shuttling via multiple spatial confinement, but also provide abundant inner space for stable reservation of active S, highly conductive networks, and maintain the structural integrity of cathode during consecutive cycling. Consequently, Li-S batteries employed with the designed W2C QD/NGM-based cathode exhibit outstanding electrochemical properties even at a high sulfur loading. The superior performance combined with the simplicity of the synthesis process represents a promising strategy for the rational design of advanced electrocatalyst for energy applications. 相似文献
77.
非接触红外辐射测温具有响应速度快、准确、便捷等优势。为实现中低温(50~400℃)物体温度的精确测量,根据双波段比色测温原理,搭建了双波段比色测温试验系统。首先对试验系统所用的试验器件进行精确标定,得到拟合曲线,用多种插值算法对曲线进行校正。然后,用设定温度的面源黑体作为试验目标来进行试验温度数据采集。实验结果表明:搭建的双波段试验系统不需要知道目标发射率,也能较为精确地得到中低温物体的真实温度。当系统标定置信度为0.95 时,物体的标准偏差在3℃以内。验证了搭建测温系统的正确性,实验装置的搭建对中低温物体真实温度的精确测量具有重要的研究意义。 相似文献
78.
79.
80.
Tianhe Huang Guan Wang Mohammad-Ali Shahbazi Yuancheng Bai Jingrui Zhang Guobing Feng Elham Asadian Fatemeh Ghorbani-Bidkorpeh Zhiyuang Yang Yuanai Li Qingqing Huo Yingxin Liu Dongfei Liu 《Advanced functional materials》2023,33(2):2210627
A versatile surface decoration strategy to efficiently encapsulate water-soluble peptides is developed. By assembling peptide molecules into nanoparticles, diverse physiochemical properties of these compacted molecules are equalized to the surface properties of nanoparticles. Primarily driven by the generic electrostatic attractions, the surface of as-prepared peptide nanoparticles is decorated with charged amino acids-grafted poly(lactic-co-glycolic acid). This adsorbed polymer layer versatilely blocks the phase transfer of peptide nanoparticles by increasing their affinity to the dispersed phase solvent molecules. Attributed to the ultrahigh encapsulation efficiencies (> 96%), the peptide mass fraction inside the obtained microcomposites is higher than 48%. The plasma calcium level has been efficiently reduced for ≈3 weeks with only one single injection of salmon calcitonin-encapsulated microcomposite in osteoporotic rats. Similarly, one single injection of exenatide-encapsulated microcomposites efficiently controls the glycemic level in type 2 diabetic rats for up to 3 weeks. Overall, the developed versatile surface decoration strategy efficiently encapsulates peptides and improves their pharmacokinetic features, regardless of the molecular structure of peptide cargos. 相似文献