全文获取类型
收费全文 | 1249篇 |
免费 | 16篇 |
国内免费 | 91篇 |
专业分类
电工技术 | 23篇 |
综合类 | 150篇 |
化学工业 | 81篇 |
金属工艺 | 83篇 |
机械仪表 | 58篇 |
建筑科学 | 68篇 |
矿业工程 | 11篇 |
能源动力 | 27篇 |
轻工业 | 106篇 |
水利工程 | 29篇 |
石油天然气 | 4篇 |
无线电 | 96篇 |
一般工业技术 | 230篇 |
冶金工业 | 108篇 |
原子能技术 | 101篇 |
自动化技术 | 181篇 |
出版年
2024年 | 11篇 |
2023年 | 65篇 |
2022年 | 40篇 |
2021年 | 30篇 |
2020年 | 19篇 |
2019年 | 26篇 |
2018年 | 12篇 |
2017年 | 4篇 |
2016年 | 10篇 |
2015年 | 30篇 |
2014年 | 38篇 |
2013年 | 57篇 |
2012年 | 82篇 |
2011年 | 90篇 |
2010年 | 35篇 |
2009年 | 21篇 |
2008年 | 130篇 |
2007年 | 109篇 |
2006年 | 113篇 |
2005年 | 104篇 |
2004年 | 73篇 |
2003年 | 44篇 |
2002年 | 28篇 |
2001年 | 21篇 |
2000年 | 35篇 |
1999年 | 13篇 |
1998年 | 9篇 |
1997年 | 5篇 |
1996年 | 7篇 |
1995年 | 9篇 |
1994年 | 4篇 |
1993年 | 9篇 |
1992年 | 11篇 |
1991年 | 7篇 |
1990年 | 15篇 |
1989年 | 9篇 |
1986年 | 6篇 |
1985年 | 1篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1972年 | 1篇 |
1966年 | 1篇 |
1957年 | 1篇 |
1956年 | 1篇 |
1954年 | 1篇 |
1948年 | 3篇 |
1946年 | 1篇 |
排序方式: 共有1356条查询结果,搜索用时 15 毫秒
1.
The Algorithm and Its Application of a Multi-Channel Adaptive Decision-Feedback Equalizer 总被引:4,自引:2,他引:2
1 IntroductionOneofthekeyproblemsinhigh speeddigitalradiocommunicationistheInter Symbol Interfer ence (ISI)causedbythemulti pathbetweenthetransmitterandthereceiver.Becauseoftherelativemovementbetweenthereceiverandthetransmitterandthecontinuouschangeoftransmissionmedia,ISIisusuallytime variant.Inthepasttwotothreedecades,abroadstudyofthetype ,structureandadaptivealgorithmofadaptiveequalizershasbeencarriedouttomitigateISI[1~ 7] .Withtheintroductionofadaptiveantennasanddiversityreceptiontec… 相似文献
2.
HE Li-xia WANG Zhong-qi SUI Hong-zhi GAN Lin 《中国原子能科学研究院年报》2006,(1):191-192
为提高加速器控制领域的智能化水平,吸收近年来IT领域中控制技术的最新发展成果,设计实现了低能强流离子束网络控制系统,可提供20mA、能量为5-100keV的两条离子束线,并进行脉冲束流和气体靶试验。实现了手动、自动建立系统真空,数字量输入输出、模拟量输入输出、串口通讯等150多个量的常规测控以及不同电位状态下多个量的报警互锁保护等功能。 相似文献
3.
4.
5.
6.
The Bisphosphonate Clodronate Modifying Hydroxyapatite Bioceramics for Bone Scaffold 总被引:3,自引:0,他引:3
LUO En HU Jing WEI Shicheng HE Gang XIAO Lin ZHAO Qiang 《武汉理工大学学报(材料科学英文版)》2005,20(B12):98-101
To investigate the efficiency of clodronate modifying HA bioceramics,and to evaluate the effect of clodronate modifying HA bioceramics on the cells in vitro,clodronate modified the porous HA bioceramics for bone scaffold by chelation .The outermost layer of the specimens was analyzd by XPS and FI-IR ,The depth profile was investigated by the argon-ion sputtering method.The cell culture test was conducted using MC3T3-E1 osteoblastic cells,The cells were inoculated and cultured on the scaffolds.Morphological observation of the cells,MTT test and ALP activity test evaluated the cell attachment ,proliferation and activity on the scaffolds.The cell culture test in cell quantity and morphology indicated active proliferation of the cells on the scaffolds.The ALP activity of the cells cultured for 3d and 7d on clodronate-HA bioceramics was slightly higher than that on HA bioceramics ,but the difference was not signifcant,This result indicated that clodronate-HA bioeramics had favorable cytocompatibility to be used as bone scaffold with potential ability to improve asteogensis. 相似文献
7.
HUANG Jianfeng CAO Liyun ZHANG Chuanbo WU Jianpeng HE Haiyan 《武汉理工大学学报(材料科学英文版)》2005,20(B12):138-140
Nano-particle hydroxyapatite ( HA ) was prepared with a novel ultrasonic precipitation process and the as-prepared nanopowder was used to produce hydroxyapatite ( HA ) coatings on titanium substrate via plasma spraying. The phase and the microstructare of the coating were characterized by X- ray diffraction (XRD) and scanning electron microscopy (SEM). Results showed that spherical particles could be prepared by ultrasonic precipitation process; and a corresponding dense HA coating with molten surface and low-porosity cross-section structure was acquired. During the plasma spraying process, new phases of Ca3 ( PO4 )2 and Ca2 P2O7 were generated. After heat-treating at 800℃ for 1 h, the contents of Ca3 ( PO4 )2 and Ca2 P2O7 decreased while HA content increased. Tensile adhesion tests showed that the plasma sprayed coating prepared with the spherical nanoparticles exhibited high tensile bond strength. 相似文献
8.
CHEN Hui ZHANG Hu HE Hui LI Gao-liang 《中国原子能科学研究院年报》2006,(1):159-159
The kinetic studies on the reactions between monomethyldrazine and Fe^3+ as well as N,N-dimethyl- hydroxylamine and Fe^3+ in nitric acid system are performed by measuring open-circuit potential of Fe^3+/ Fe^2+. The effect of some factors such as the concentration of MMH or DMHAN, the concentration of nitric acid, ionic strength, temperature and the concentration of Fe^3+ on the reaction rate is also studied. 相似文献
9.
ListofSymbol B———Buoyancy ,m·s- 2 ; c———Concentrationofsoluteelement ; Cμ———Turbulentconstant; D———Diffusivityofsoluteelement ,m2 ·s- 1 ; fl,fs———Liquidandsolidfraction ; fμ———Turbulentcoefficient ; h———Enthalpy ,J·kg- 1 ; k———Turbulentkineticenergy ,m2 ·s- 2 ; kp———Equilibriumpartitioncoefficient; Kp———Permeabilityofmushyzone ,m2 ; K0 ———Permeabilitycoefficient; p———Pressure ,Pa ; Pr———Prandtlnumber ;… 相似文献
10.