全文获取类型
收费全文 | 6756篇 |
免费 | 637篇 |
国内免费 | 417篇 |
专业分类
电工技术 | 367篇 |
综合类 | 431篇 |
化学工业 | 1048篇 |
金属工艺 | 323篇 |
机械仪表 | 488篇 |
建筑科学 | 631篇 |
矿业工程 | 196篇 |
能源动力 | 195篇 |
轻工业 | 554篇 |
水利工程 | 146篇 |
石油天然气 | 317篇 |
武器工业 | 54篇 |
无线电 | 894篇 |
一般工业技术 | 747篇 |
冶金工业 | 297篇 |
原子能技术 | 141篇 |
自动化技术 | 981篇 |
出版年
2024年 | 28篇 |
2023年 | 113篇 |
2022年 | 207篇 |
2021年 | 275篇 |
2020年 | 235篇 |
2019年 | 168篇 |
2018年 | 185篇 |
2017年 | 222篇 |
2016年 | 198篇 |
2015年 | 290篇 |
2014年 | 390篇 |
2013年 | 406篇 |
2012年 | 439篇 |
2011年 | 481篇 |
2010年 | 439篇 |
2009年 | 471篇 |
2008年 | 436篇 |
2007年 | 408篇 |
2006年 | 410篇 |
2005年 | 323篇 |
2004年 | 224篇 |
2003年 | 180篇 |
2002年 | 207篇 |
2001年 | 158篇 |
2000年 | 155篇 |
1999年 | 153篇 |
1998年 | 111篇 |
1997年 | 74篇 |
1996年 | 94篇 |
1995年 | 47篇 |
1994年 | 53篇 |
1993年 | 34篇 |
1992年 | 34篇 |
1991年 | 32篇 |
1990年 | 25篇 |
1989年 | 20篇 |
1988年 | 9篇 |
1987年 | 8篇 |
1986年 | 11篇 |
1985年 | 10篇 |
1984年 | 4篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 6篇 |
1976年 | 8篇 |
1973年 | 2篇 |
排序方式: 共有7810条查询结果,搜索用时 15 毫秒
1.
This paper is prepared in honour of Professor E.T. Brown for his outstanding contributions to rock mechanics and geotechnical engineering and also for his personal influence on the first author's research career in geomechanics and geotechnical engineering. As a result, we have picked a topic that reflects two key research areas in which Professor E.T. Brown has made seminal contributions over a long and distinguished career. These two areas are concerned with the application of the critical state concept to modelling geomaterials and the analysis of underground excavation or tunnelling in geomaterials.Partially due to Professor Brown's influence, the first author has also been conducting research in these two areas over many years. In particular, this paper aims to describe briefly the development of a unified critical state model for geomaterials together with an application to cavity contraction problems and tunnelling in soils. 相似文献
2.
3.
Dr. Yahu A. Liu Dr. Qihui Jin Qiang Ding Dr. Xueshi Hao Tingting Mo Shanshan Yan Dr. Yefen Zou Dr. Zhihong Huang Xiaoyue Zhang Wenqi Gao Dr. Tom Y.-H. Wu Chun Li Dr. Badry Bursalaya Dr. Michael Di Donato Dr. You-Qing Zhang Lisa Deaton Dr. Weijun Shen Dr. Brandon Taylor Anwesh Kamireddy Dr. George Harb Dr. Jing Li Dr. Yong Jia Dr. Andrew M. Schumacher Dr. Bryan Laffitte Dr. Richard Glynne Dr. Shifeng Pan Dr. Peter McNamara Dr. Valentina Molteni Dr. Jon Loren 《ChemMedChem》2020,15(16):1562-1570
Loss of β-cell mass and function can lead to insufficient insulin levels and ultimately to hyperglycemia and diabetes mellitus. The mainstream treatment approach involves regulation of insulin levels; however, approaches intended to increase β-cell mass are less developed. Promoting β-cell proliferation with low-molecular-weight inhibitors of dual-specificity tyrosine-regulated kinase 1A (DYRK1A) offers the potential to treat diabetes with oral therapies by restoring β-cell mass, insulin content and glycemic control. GNF4877, a potent dual inhibitor of DYRK1A and glycogen synthase kinase 3β (GSK3β) was previously reported to induce primary human β-cell proliferation in vitro and in vivo. Herein, we describe the lead optimization that lead to the identification of GNF4877 from an aminopyrazine hit identified in a phenotypic high-throughput screening campaign measuring β-cell proliferation. 相似文献
4.
5.
采用新工艺回收7-氨基-3-脱乙酰氧基头孢烷酸(7-ADCA)生产中产生的苯乙酸,并对苯乙酸回收过程中产生的废硫酸进行处理。采用硫酸(9 8%)洗涤二氯甲烷,硫酸与二氯甲烷适宜的体积比为1∶50,洗涤好的二氯甲烷中含苯乙酸4%。蒸馏出二氯甲烷,趁热向熔融苯乙酸中加入母液,降温析出苯乙酸。晾干的苯乙酸为白色鳞片状,含量大于99%,苯乙酸母液补充部分清水套用到下一批析出苯乙酸。废浓硫酸用芬顿试剂氧化,控制80℃氧化4h,双氧水和七水硫酸亚铁重量比为6∶1,废浓硫酸COD下降85%以上。氧化结束后向废硫酸中加入铁粉和双氧水,制得聚合硫酸铁。 相似文献
6.
UML在网络安全监控系统建模中的应用 总被引:4,自引:0,他引:4
本文首先介绍了UML的特性,然后运用UML对网络安全监控系统中的数据采集系统进行了可视化的建模,建立了系统的需求模型和设计模型的各种视图,最后总结了用UML进行系统需求分析和设计的优越性. 相似文献
7.
Yong Zhang Yuanlong Mo Xiaolan Zhou Jianqing Li 《Journal of Infrared, Millimeter and Terahertz Waves》2003,24(12):2085-2094
Recently disk-loaded waveguide has been widely used in high-power traveling wave tubes (HPTWT). It has been shown in many experiments that the interaction efficiency and output power can be increased greatly by injecting plasma into the vacuum microwave device. Using field analysis, the dispersion characteristics and the interaction impedance of the disk-loaded waveguide filled with plasma are analyzed in a strong longitudinal magnetic field. In conclusion, the frequency of the TM01 mode increases as the density of the plasma increases. It also can be found when the plasma density increases to a large scale, the TM01 mode of the disk-loaded waveguide overlaps the TG mode, these two modes couple each other and form the new hybrid modes. 相似文献
8.
本文主要介绍了CPU芯片封装技术的发展演变,以及未来的芯片封装技术。同时,从中可以看出芯片技术与封装技术相互促进,协调发展密不可分的关系。 相似文献
9.
10.
A Linear Cross-Coupled Control System for High-Speed Machining 总被引:4,自引:0,他引:4
Q. Zhong Y. Shi J. Mo S. Huang 《The International Journal of Advanced Manufacturing Technology》2002,19(8):558-563
We present a linear cross-coupled controller to improve highspeed contouring accuracy independently of tracking accuracy in
a biaxial machine tool feed drive servomechanism. Unlike conventional cross-coupled controllers, the cross-coupled controller
presented here is a linear system, so it is very easy to perform the stability and steady-state error analysis, and to optimise
the controller parameters. The proposed controller is evaluated experimentally on a CNC LOM machine and compared to an uncoupled
controller and a conventional cross-coupled controller. Controller performance is evaluated for a circular contour at a feedrate
of 30 m min _1 . The experimental results show that the proposed controller can greatly reduce the contour error at large feedrates. The
linear cross-coupled controller is simple to implement and is practical. 相似文献