全文获取类型
收费全文 | 5936篇 |
免费 | 151篇 |
国内免费 | 206篇 |
专业分类
电工技术 | 137篇 |
综合类 | 40篇 |
化学工业 | 754篇 |
金属工艺 | 288篇 |
机械仪表 | 88篇 |
建筑科学 | 141篇 |
矿业工程 | 17篇 |
能源动力 | 94篇 |
轻工业 | 312篇 |
水利工程 | 15篇 |
石油天然气 | 331篇 |
武器工业 | 13篇 |
无线电 | 351篇 |
一般工业技术 | 616篇 |
冶金工业 | 2497篇 |
原子能技术 | 42篇 |
自动化技术 | 557篇 |
出版年
2022年 | 47篇 |
2021年 | 85篇 |
2020年 | 44篇 |
2019年 | 60篇 |
2018年 | 86篇 |
2017年 | 83篇 |
2016年 | 86篇 |
2015年 | 91篇 |
2014年 | 118篇 |
2013年 | 178篇 |
2012年 | 181篇 |
2011年 | 290篇 |
2010年 | 245篇 |
2009年 | 245篇 |
2008年 | 253篇 |
2007年 | 226篇 |
2006年 | 272篇 |
2005年 | 230篇 |
2004年 | 238篇 |
2003年 | 189篇 |
2002年 | 235篇 |
2001年 | 195篇 |
2000年 | 155篇 |
1999年 | 179篇 |
1998年 | 181篇 |
1997年 | 172篇 |
1996年 | 119篇 |
1995年 | 130篇 |
1994年 | 137篇 |
1993年 | 144篇 |
1992年 | 97篇 |
1991年 | 52篇 |
1990年 | 98篇 |
1989年 | 100篇 |
1988年 | 72篇 |
1987年 | 60篇 |
1986年 | 66篇 |
1985年 | 54篇 |
1984年 | 51篇 |
1983年 | 45篇 |
1981年 | 56篇 |
1979年 | 40篇 |
1978年 | 35篇 |
1977年 | 37篇 |
1976年 | 32篇 |
1975年 | 41篇 |
1974年 | 34篇 |
1971年 | 79篇 |
1970年 | 41篇 |
1968年 | 35篇 |
排序方式: 共有6293条查询结果,搜索用时 15 毫秒
981.
Laurent Liscia 《中国标准化(英文版)》2011,(5):56-61
The business of ICT (Information and Communications Technology) standards is more different in China than it is in Europe or in Japan.While it started out as a centralized effort over the millennia (yes,you read me right),in the past twenty years it has been driven equally by local government,state-owned enterprises and private enterprises either in standards organizations or trade associations.This has resulted in what meteorologists might call a turbulent situation.The current goals of standardization in China include:a push for quality and safety;encouraging home-grown innovation,whether regionally or nationally;influencing the direction of innovation internationally;and emphasizing market-driven approaches.Eventually China will be a formidable standards player.There is direct business value in helping Chinese companies master the art of participating in de jure and de facto standards bodies,in watching and analyzing their participation strategies - and in participating as a company or an organization because innovation is increasingly being shaped in standards. 相似文献
982.
Sassolas B Benoît Q Flaminio R Forest D Franc J Galimberti M Lacoudre A Michel C Montorio JL Morgado N Pinard L 《Applied optics》2011,50(13):1894-1899
Gravitational-wave detectors such as Virgo and the laser interferometric gravitational-wave observatory (LIGO) use a long-baseline Michelson interferometer with Fabry-Perot cavities in the arms to search for gravitational waves. The symmetry between the two Fabry-Perot cavities is crucial to reduce the interferometer's sensitivity to the laser amplitude and frequency noise. To this purpose, the transmittance of the mirrors in both cavities should be as close as possible. This paper describes the realization and the characterization of the first twin large low-loss mirrors with transmissions differing by less than 0.01%. 相似文献
983.
Puente D. Sancho J.I. Garcia J. No J.D. Gomez J. Valderas D. 《Microwaves, Antennas & Propagation, IET》2009,3(4):645-653
A method for matching dipole antennas to capacitive or inductive arbitrary complex impedances is proposed for ultra high frequency radio frequency identification (RFID) tag antenna designs. It can be applied to straight, capacitive-loaded, meander or any small high-Q dipole topology. For this purpose, design stages are provided with the corresponding formulas. The reflection coefficient simulations and measurements of four implemented prototypes show the expected output when the RFID frequency band, bandwidth, chip impedance and maximum tag size are required as inputs for the method. The eventual S11 < 10 dB bandwidth depends on the chip impedance Q factor and the antenna size. How this bandwidth is manifested in terms of the read range is also discussed. A length ratio of up to 31.1% regarding the standard Λ/2 dipole at resonance is obtained. 相似文献
984.
Lipid and Nucleic Acid Chemistries: Combining the Best of Both Worlds to Construct Advanced Biomaterials 下载免费PDF全文
Julie Baillet Valérie Desvergnes Aladin Hamoud Laurent Latxague Philippe Barthélémy 《Advanced materials (Deerfield Beach, Fla.)》2018,30(11)
Hybrid synthetic amphiphilic biomolecules are emerging as promising supramolecular materials for biomedical and technological applications. Herein, recent progress in the field of nucleic acid based lipids is highlighted with an emphasis on their molecular design, synthesis, supramolecular properties, physicochemical behaviors, and applications in the field of health science and technology. In the first section, the design and the study of nucleolipids are in focus and then the glyconucleolipid family is discussed. In the last section, recent contributions of responsive materials involving nucleolipids and their use as smart drug delivery systems are discussed. The supramolecular materials generated by nucleic acid based lipids open new challenges for biomedical applications, including the fields of medicinal chemistry, biosensors, biomaterials for tissue engineering, drug delivery, and the decontamination of nanoparticles. 相似文献
985.
Detection of Glutamate and Acetylcholine with Organic Electrochemical Transistors Based on Conducting Polymer/Platinum Nanoparticle Composites 下载免费PDF全文
986.
Nanoparticles: “Hyper‐bright” Near‐Infrared Emitting Fluorescent Organic Nanoparticles for Single Particle Tracking (Adv. Mater. 14/2014) 下载免费PDF全文
987.
Hydrogels: Assembly of Viral Hydrogels for Three‐Dimensional Conducting Nanocomposites (Adv. Mater. 30/2014) 下载免费PDF全文
988.
A key, yet often neglected, component of digital evolution and evolutionary models is the ‘selection method’ which assigns fitness (number of offspring) to individuals based on their performance scores (efficiency in performing tasks). Here, we study with formal analysis and numerical experiments the evolution of cooperation under the five most common selection methods (proportionate, rank, truncation-proportionate, truncation-uniform and tournament). We consider related individuals engaging in a Prisoner''s Dilemma game where individuals can either cooperate or defect. A cooperator pays a cost, whereas its partner receives a benefit, which affect their performance scores. These performance scores are translated into fitness by one of the five selection methods. We show that cooperation is positively associated with the relatedness between individuals under all selection methods. By contrast, the change in the performance benefit of cooperation affects the populations’ average level of cooperation only under the proportionate methods. We also demonstrate that the truncation and tournament methods may introduce negative frequency-dependence and lead to the evolution of polymorphic populations. Using the example of the evolution of cooperation, we show that the choice of selection method, though it is often marginalized, can considerably affect the evolutionary dynamics. 相似文献
989.
Assembly of a Bacteriophage‐Based Template for the Organization of Materials into Nanoporous Networks 下载免费PDF全文
990.
Self‐Powered Cardiac Pacemaker Enabled by Flexible Single Crystalline PMN‐PT Piezoelectric Energy Harvester 下载免费PDF全文