全文获取类型
收费全文 | 21958篇 |
免费 | 1675篇 |
国内免费 | 315篇 |
专业分类
电工技术 | 538篇 |
综合类 | 361篇 |
化学工业 | 4851篇 |
金属工艺 | 906篇 |
机械仪表 | 1286篇 |
建筑科学 | 1033篇 |
矿业工程 | 251篇 |
能源动力 | 699篇 |
轻工业 | 1879篇 |
水利工程 | 148篇 |
石油天然气 | 564篇 |
武器工业 | 60篇 |
无线电 | 2978篇 |
一般工业技术 | 4035篇 |
冶金工业 | 1927篇 |
原子能技术 | 265篇 |
自动化技术 | 2167篇 |
出版年
2024年 | 50篇 |
2023年 | 298篇 |
2022年 | 492篇 |
2021年 | 711篇 |
2020年 | 543篇 |
2019年 | 581篇 |
2018年 | 624篇 |
2017年 | 729篇 |
2016年 | 786篇 |
2015年 | 724篇 |
2014年 | 1054篇 |
2013年 | 1443篇 |
2012年 | 1318篇 |
2011年 | 1629篇 |
2010年 | 1209篇 |
2009年 | 1174篇 |
2008年 | 1162篇 |
2007年 | 932篇 |
2006年 | 851篇 |
2005年 | 735篇 |
2004年 | 618篇 |
2003年 | 590篇 |
2002年 | 503篇 |
2001年 | 424篇 |
2000年 | 393篇 |
1999年 | 495篇 |
1998年 | 692篇 |
1997年 | 538篇 |
1996年 | 354篇 |
1995年 | 279篇 |
1994年 | 260篇 |
1993年 | 238篇 |
1992年 | 156篇 |
1991年 | 146篇 |
1990年 | 123篇 |
1989年 | 123篇 |
1988年 | 82篇 |
1987年 | 73篇 |
1986年 | 67篇 |
1985年 | 83篇 |
1984年 | 77篇 |
1983年 | 49篇 |
1982年 | 48篇 |
1981年 | 47篇 |
1980年 | 47篇 |
1979年 | 40篇 |
1977年 | 53篇 |
1976年 | 83篇 |
1975年 | 42篇 |
1973年 | 33篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
Feng Feng Young Bae Jun 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2009,13(11):1113-1121
The notion of an inductive semimodule over an ordered *-semiring is introduced and some related properties are investigated.
Inductive semimodules are extensions of several important algebraic structures such as Kleene modules, Kleene algebras and
inductive *-semirings. We prove that an inductive semimodule over an ordered *-semiring K is a Kleene module if and only if K is a Kleene algebra. Moreover, we establish that the vector module of an inductive semimodule over an ordered Conway semiring
is again an inductive semimodule over the matrix semiring. Consequently, in an inductive semimodule over an ordered Conway
semiring, least solutions to linear inequation systems can be denoted by linear expressions, avoiding the least fixed point
operator. In addition, we also introduce a related notion called weak inductive semimodules, and propose several open problems
on them.
相似文献
Young Bae JunEmail: |
62.
The stable range of PbTiO3 sol and the processing conditions of uniform thin films were investigated using a solution of titanium isopropoxide, three kinds of alkanolamines (monoethanolamine, diethanolamine, triethanolamine), lead acetate trihydrate and isopropanol. Depending on the sol state with various alkanolamine/alkoxide molar ratios, diethanolamine (DEA) was very effective in preparing uniform and dense oxide films through room-temperature reaction, owing to its superior stability during the hydrolysis and condensation reaction. Perovskite PbTiO3 thin films were obtained on oxidized silicon wafer above 550 °C and completely pure films were obtained at 650 °C using DEA as a complexing agent. The dielectric constant and loss tangent of these thin films fired at 650 °C for 30 min were found to be 240 and 0.01 at 1 kHz, respectively. 相似文献
63.
Yin Lifeng Kong Yanggang Guo Mingkang Zhang Xingyu Yan Wenlong Zhang Hua 《Magma (New York, N.Y.)》2023,36(4):651-658
Magnetic Resonance Materials in Physics, Biology and Medicine - This study aims to present a radiomic application in diagnosing the long head of biceps (LHB) tendinitis. Moreover, we evaluated... 相似文献
64.
Designing Metallic and Insulating Nanocrystal Heterostructures to Fabricate Highly Sensitive and Solution Processed Strain Gauges for Wearable Sensors 下载免费PDF全文
Woo Seok Lee Seung‐Wook Lee Hyungmok Joh Mingi Seong Haneun Kim Min Su Kang Ki‐Hyun Cho Yun‐Mo Sung Soong Ju Oh 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(47)
All‐solution processed, high‐performance wearable strain sensors are demonstrated using heterostructure nanocrystal (NC) solids. By incorporating insulating artificial atoms of CdSe quantum dot NCs into metallic artificial atoms of Au NC thin film matrix, metal–insulator heterostructures are designed. This hybrid structure results in a shift close to the percolation threshold, modifying the charge transport mechanism and enhancing sensitivity in accordance with the site percolation theory. The number of electrical pathways is also manipulated by creating nanocracks to further increase its sensitivity, inspired from the bond percolation theory. The combination of the two strategies achieves gauge factor up to 5045, the highest sensitivity recorded among NC‐based strain gauges. These strain sensors show high reliability, durability, frequency stability, and negligible hysteresis. The fundamental charge transport behavior of these NC solids is investigated and the combined site and bond percolation theory is developed to illuminate the origin of their enhanced sensitivity. Finally, all NC‐based and solution‐processed strain gauge sensor arrays are fabricated, which effectively measure the motion of each finger joint, the pulse of heart rate, and the movement of vocal cords of human. This work provides a pathway for designing low‐cost and high‐performance electronic skin or wearable devices. 相似文献
65.
Monitoring the Dynamic Process of Formation of Plasmonic Molecular Junctions during Single Nanoparticle Collisions 下载免费PDF全文
Jing Guo Jie Pan Shuai Chang Xuewen Wang Na Kong Wenrong Yang Jin He 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(15)
The capability to study the dynamic formation of plasmonic molecular junction is of fundamental importance, and it will provide new insights into molecular electronics/plasmonics, single‐entity electrochemistry, and nanooptoelectronics. Here, a facile method to form plasmonic molecular junctions is reported by utilizing single gold nanoparticle (NP) collision events at a highly curved gold nanoelectrode modified with a self‐assembled monolayer. By using time‐resolved electrochemical current measurement and surface‐enhanced Raman scattering spectroscopy, the current changes and the evolution of interfacial chemical bonding are successfully observed in the newly formed molecular tunnel junctions during and after the gold NP “hit‐n‐stay” and “hit‐n‐run” collision events. The results lead to an in‐depth understanding of the single NP motion and the associated molecular level changes during the formation of the plasmonic molecular junctions in a single NP collision event. This method also provides a new platform to study molecular changes at the single molecule level during electron transport in a dynamic molecular tunnel junction. 相似文献
66.
Qingqing Xiong Gha Young Lee Jianxun Ding Wenliang Li Jinjun Shi 《Nano Research》2018,11(10):5281-5309
As an attractive alternative to plasmid DNA, messenger RNA (mRNA) has recently emerged as a promising class of nucleic acid therapeutics for biomedical applications. Advances in addressing the inherent shortcomings of mRNA and in the development of nanoparticle-based delivery systems have prompted the development and clinical translation of mRNA-based medicines. In this review, we discuss the chemical modification strategies of mRNA to improve its stability, minimize immune responses, and enhance translational efficacy. We also highlight recent progress in nanoparticle-based mRNA delivery. Considerable attention is given to the increasingly widespread applications of mRNA nanomedicine in the biomedical fields of vaccination, protein-replacement therapy, gene editing, and cellular reprogramming and engineering. 相似文献
67.
Jiabin Liu Jiawei Deng Yangyang Zhu Xiaokang Geng Lifu Zhang Sang Young Jeong Dan Zhou Han Young Woo Dong Chen Feiyan Wu Lie Chen 《Advanced materials (Deerfield Beach, Fla.)》2023,35(1):2208008
With the great potential of the all-polymer solar cells for large-area wearable devices, both large-area device efficiency and mechanical flexibility are very critical but attract limited attention. In this work, from the perspective of the polymer configurations, two types of terpolymer acceptors PYTX-A and PYTX-B (X = Cl or H) are developed. The configuration difference caused by the replacement of non-conjugated units results in distinct photovoltaic performance and mechanical flexibility. Benefiting from a good match between the intrinsically slow film-forming of the active materials and the technically slow film-forming of the blade-coating process, the toluene-processed large-area (1.21 cm2) binary device achieves a record efficiency of 14.70%. More importantly, a new parameter of efficiency stretchability factor (ESF) is proposed for the first time to comprehensively evaluate the overall device performance. PM6:PYTCl-A and PM6:PYTCl-B yield significantly higher ESF than PM6:PY-IT. Further blending with non-conjugated polymer donor PM6-A, the best ESF of 3.12% is achieved for PM6-A:PYTCl-A, which is among the highest comprehensive performances. 相似文献
68.
Highly efficient, widely tunable, 10-Hz parametric amplifier pumped by frequency-doubled femtosecond Ti:sapphire laser pulses 总被引:5,自引:0,他引:5
We report a 10-Hz, highly efficient, widely tunable (from the visible to the IR), broadband femtosecond optical parametric generator and optical parametric amplifier (OPA) in BBO, LBO, and CBO crystals pumped by the frequency-doubled output of a regeneratively amplified Ti:sapphire laser at 400 nm. The output of the system is continuously tunable from 440 nm to 2.5 mum with a maximum overall efficiency of ~25% at 670 nm and an optical conversion efficiency of more than 36% in the OPA stage. The effects of the seed beam energy, the type of the crystal and the crystal length, and the pumping energy of the output of the OPA, such as the optical efficiency, the bandwidth, the pulse duration, and the group velocity mismatch between the signal and the idler and between the seeder and the pump, are investigated. The results provide useful information for optimization of the design of the system. 相似文献
69.
70.
The "new science" of wetland restoration 总被引:1,自引:0,他引:1
Young P 《Environmental science & technology》1996,30(7):292A-296A
The intricate workings of natural wetlands are slowly yielding their secrets to scientists applying a number of experimental approaches. 相似文献