全文获取类型
收费全文 | 1662469篇 |
免费 | 47781篇 |
国内免费 | 18593篇 |
专业分类
电工技术 | 49756篇 |
技术理论 | 15篇 |
综合类 | 22043篇 |
化学工业 | 293860篇 |
金属工艺 | 75330篇 |
机械仪表 | 54848篇 |
建筑科学 | 61959篇 |
矿业工程 | 18325篇 |
能源动力 | 56446篇 |
轻工业 | 119398篇 |
水利工程 | 19241篇 |
石油天然气 | 48987篇 |
武器工业 | 2280篇 |
无线电 | 219828篇 |
一般工业技术 | 298052篇 |
冶金工业 | 154514篇 |
原子能技术 | 36382篇 |
自动化技术 | 197579篇 |
出版年
2022年 | 13353篇 |
2021年 | 25706篇 |
2020年 | 19473篇 |
2019年 | 20526篇 |
2018年 | 21347篇 |
2017年 | 21411篇 |
2016年 | 27515篇 |
2015年 | 26785篇 |
2014年 | 40527篇 |
2013年 | 101601篇 |
2012年 | 50219篇 |
2011年 | 62254篇 |
2010年 | 55833篇 |
2009年 | 63673篇 |
2008年 | 55933篇 |
2007年 | 51946篇 |
2006年 | 55422篇 |
2005年 | 47924篇 |
2004年 | 46896篇 |
2003年 | 45564篇 |
2002年 | 44427篇 |
2001年 | 40235篇 |
2000年 | 38689篇 |
1999年 | 37825篇 |
1998年 | 42482篇 |
1997年 | 38551篇 |
1996年 | 35669篇 |
1995年 | 31502篇 |
1994年 | 29437篇 |
1993年 | 28796篇 |
1992年 | 26209篇 |
1991年 | 23065篇 |
1990年 | 23291篇 |
1989年 | 22155篇 |
1988年 | 20581篇 |
1987年 | 18854篇 |
1986年 | 18185篇 |
1985年 | 21458篇 |
1984年 | 21801篇 |
1983年 | 19735篇 |
1982年 | 18854篇 |
1981年 | 18921篇 |
1980年 | 17585篇 |
1979年 | 18129篇 |
1978年 | 17393篇 |
1977年 | 16931篇 |
1976年 | 17374篇 |
1975年 | 15689篇 |
1974年 | 15235篇 |
1973年 | 15333篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Programming and Computer Software - In this paper, we overview the approaches and techniques employed by the Svace static analysis tool for intraprocedural analysis. This analysis implies the... 相似文献
992.
Neural Computing and Applications - The goal of this paper is to introduce a novel hybrid model called multi-fuzzy N-soft set, and to design an adjustable decision-making methodology for solving... 相似文献
993.
A device able to electrokinetically concentrate cationic samples has many potential medical and industrial applications, but until now has remained undeveloped due to the lack of a commercial anion-permselective material leading to a prohibitively complex fabrication procedure. Herein, a novel multiscale-porous anion exchange membrane (MP-AEM) that enables the convenient and scalable electrokinetic concentration of cationic species is proposed. A mechanically enhanced multiscale-porous structure with a solid framework is realized by adopting polyester resin as an additive to overcome the intrinsic limitations of the AEM material. The scalable MP-AEM-embedded electrokinetic concentrator is devised based on the peculiar properties of the MP-AEM that for allow both ion and fluid transport. With the MP-AEM, the concentrator is fabricated in a highly streamlined manner consisting only of a simple insertion and assembly. The concentration performance of the MP-AEM-embedded electrokinetic concentrator is demonstrated with a positively charged fluorescent dye and a fluorescein-labeled protein, and the results show enrichment factors of 250 and 500, respectively. The MP-AEM makes cationic electrokinetic concentration more accessible and scalable, thereby enabling further progress in a wide range of fields. 相似文献
994.
Programming and Computer Software - Modern computer systems often include specialized processors that are programmed in domain-specific languages. The compiler-in-the-loop technology, which assumes... 相似文献
995.
Wireless Personal Communications - This paper considers half-duplex cooperative spectrum sharing scheme where both primary and secondary systems mutually cooperate with each other to exploit... 相似文献
996.
We show that in the presence of magnetic field, two superconducting phases with the center-of-mass momentum of Cooper pair parallel to the magnetic field are induced in Dresselhaus spin–orbit-coupled superconductor. Specifically, at small magnetic field, the center-of-mass momentum is induced due to the energy-spectrum distortion and no unpairing region with vanishing singlet correlation appears. We refer to this superconducting state as the drift-BCS state. By further increasing the magnetic field, the superconducting state falls into the Fulde–Ferrell state with the emergence of the unpairing regions. The observed abrupt enhancement of the center-of-mass momenta and suppression on the order parameters during the transition indicate the occurrence of a first-order phase transition. Enhanced Pauli limit and hence enlarged magnetic-field regime of the Fulde–Ferrell state, due to the spin-flip terms of the spin–orbit coupling, are revealed. We also address the triplet correlations induced by the spin–orbit coupling, and show that the Cooper-pair spin polarizations, generated by the magnetic field and center-of-mass momentum with the triplet correlations exhibit totally different magnetic-field dependences between the drift-BCS and Fulde–Ferrell states. 相似文献
997.
P. Sampath Brijesh Kakarla Raghava Reddy C. Venkata Reddy Nagaraj P. Shetti Raghavendra V. Kulkarni Anjanapura V. Raghu 《化学工程与技术》2020,43(7):1240-1248
Hydrogen fuel is a promising alternative to fossil fuels because of its energy content, clean nature, and fuel efficiency. However, it is not readily available. Most current producion processes are very energy intensive and emit carbon dioxide. Therefore, this article reviews technological options for hydrogen production that are eco-friendly and generate clean hydrogen fuel. Biological methods, such different fermentation processes and photolysis are discussed together with the required substrates and the process efficiency. 相似文献
998.
为满足后续生物处理单元对固体悬浮物(SS)和铁浓度的进水要求,采用磁絮凝强化技术对厌氧消化污泥脱水液进行预处理。通过正交试验和单因素试验,本文考察了混凝水力条件、聚合氯化铝(PAC)投加量、聚丙烯酰胺(PAM)投加量、磁粉投加量及药剂投加顺序对磁絮凝效果的影响。试验结果表明:磁絮凝强化技术在快搅300r/min(2min)、慢搅100r/min(15min)、静置10min时,依次投加磁粉(40mg/L)、PAC(30mg/L)、PAM(4mg/L)时处理效果最好。在此运行条件下,SS和Fe3+去除率分别为97.61%、98.24%、絮凝指数(FI值)取得最大值、zeta电位绝对值最小,絮凝效果最佳。与对照相比,磁絮凝强化技术对SS和Fe3+去除率分别可提高3.70%和10.82%,同时絮体最大沉降速度可提高33%。磁絮凝技术处理后的出水不仅可以满足后续生物处理单元对SS和铁浓度的要求,还可以有效提高磁絮凝体的沉降速度,减小沉淀时间,具有较好的实用价值。 相似文献
999.
1000.
This study addresses the thermo‐diffusion and the diffusion‐thermo phenomena in a semi‐infinite absorbent channel whose walls are contracting/expanding, with heat source/sink effects. The governing partial differential equations with suitable boundary conditions are transformed to a system of dimensionless ordinary differential equations. An analytic solution of the problem has been found using a technique called homotopy analysis method (HAM). HAM gives consistently valid answers to the problem over an extensive variety of parameters and also provides better accuracy. To validate the analytical results, a comparison has been presented with a numerical solution calculated by using the parallel shooting method. The effects of dimensionless parameters, that is, deformation parameter, Reynolds number, Soret and Dufour numbers, and heat source/sink parameter on the expressions of velocity, temperature, and concentration profiles are analyzed graphically to understand the physics of the deformable channel. It has been noted that the velocity across the channel is higher for the expanding channel, as compared to that for the contracting channel. Also the Soret and Dufour number increases the temperature of the fluid, and decreases the concentration. The temperature profile has an increasing behavior in the case of heat source, and a decreasing behavior in the case of heat sink. 相似文献