全文获取类型
收费全文 | 66679篇 |
免费 | 5920篇 |
国内免费 | 3167篇 |
专业分类
电工技术 | 4158篇 |
技术理论 | 9篇 |
综合类 | 4332篇 |
化学工业 | 11271篇 |
金属工艺 | 3469篇 |
机械仪表 | 4005篇 |
建筑科学 | 4730篇 |
矿业工程 | 1901篇 |
能源动力 | 2047篇 |
轻工业 | 4154篇 |
水利工程 | 1287篇 |
石油天然气 | 3654篇 |
武器工业 | 735篇 |
无线电 | 8170篇 |
一般工业技术 | 8112篇 |
冶金工业 | 3519篇 |
原子能技术 | 819篇 |
自动化技术 | 9394篇 |
出版年
2024年 | 316篇 |
2023年 | 1110篇 |
2022年 | 2133篇 |
2021年 | 2933篇 |
2020年 | 2198篇 |
2019年 | 1866篇 |
2018年 | 2037篇 |
2017年 | 2148篇 |
2016年 | 1945篇 |
2015年 | 2706篇 |
2014年 | 3240篇 |
2013年 | 4052篇 |
2012年 | 4314篇 |
2011年 | 4512篇 |
2010年 | 3981篇 |
2009年 | 3886篇 |
2008年 | 3701篇 |
2007年 | 3547篇 |
2006年 | 3620篇 |
2005年 | 2968篇 |
2004年 | 2204篇 |
2003年 | 1911篇 |
2002年 | 1964篇 |
2001年 | 1782篇 |
2000年 | 1577篇 |
1999年 | 1616篇 |
1998年 | 1394篇 |
1997年 | 1197篇 |
1996年 | 984篇 |
1995年 | 827篇 |
1994年 | 624篇 |
1993年 | 508篇 |
1992年 | 403篇 |
1991年 | 320篇 |
1990年 | 233篇 |
1989年 | 213篇 |
1988年 | 165篇 |
1987年 | 105篇 |
1986年 | 108篇 |
1985年 | 78篇 |
1984年 | 37篇 |
1983年 | 32篇 |
1982年 | 45篇 |
1981年 | 34篇 |
1980年 | 25篇 |
1979年 | 21篇 |
1977年 | 16篇 |
1976年 | 19篇 |
1974年 | 13篇 |
1973年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
神马尼龙66高强力轻型帘布在保持帘布高强力、尺寸稳定性、耐热性、耐疲劳、耐冲击的良好特性的前提下,采用SNT高强度工业丝生产技术,充分挖掘工业丝的强力优势,把富余的强力通过进一步降低纤维密度转化为帘布面积优势的扩大,从而提高轮胎生产的帘布出胎率,使轮胎生产厂享受尼龙66帘布品质的同时,实现降低成本的目的。 相似文献
12.
13.
Xiaojun Xie Yonghong Cheng Hong Wang Qian Wang Xiaolin Chen Caixin Sun 《Ceramics International》2008,34(4):689-693
In the ideal A2B2O6O′ pyrochlore structure, the x-value of O atom position is a variable parameter. In Bi1.5ZnNb1.5−xTaxO7 (BZNT) cubic pyrochlores, the x-values alter with the different compositions of Nb/Ta. In this work, a series of initial models for BZNT were established by analyzing X-ray diffraction data. Then three structure modifying methods, including Rietveld refinement, Rietveld refinement with energy and geometry optimization based on quantum mechanics, were employed to obtain the precise models using Materials Studio. Moreover, the reflectivities of BZNT were computed by quantum mechanical simulation based on the refined models. Comparing the simulation results from different modifying models with the experimental results, it is found that Rietveld refinement with energy optimization is the most accurate method for BZNT pyrochlores. According to the simulation results, the different reflectivities correspond well with various x-values of O atom positions in BZNT pyrochlores. 相似文献
14.
15.
A new torque estimator for switched reluctance motor (SRM) drives based on 2-D rotary regression analysis is presented in this paper. The proposed torque estimator is composed of a bicubic regressive polynomial as a function of rotor position and input current. The regressive coefficients can be computed offline or online from the torque characteristics acquired either experimentally or from numerical computation. Furthermore, a torque estimation method by taking mutual coupling into consideration is proposed. It can be seen that the estimated and experimentally obtained self-coupling and mutual-coupling torque characteristics are in good agreement with each other. In addition, the dynamic torque waveforms with and without the mutual coupling, estimated by the proposed estimator, are found to be virtually the same as those obtained from the bicubic spline interpolation for SRM drives with single-pulse voltage, hysteresis current chopping, as well as with voltage pulse width modulation control. The success of all the case studies being reported is a good validation of the usefulness and accuracy of the proposed real-time torque estimator that, as described in this paper, can be used to quickly estimate the instantaneous output torque of SRM drives. 相似文献
16.
Junwei Fu Zhengbiao Zhang Zhenping Cheng Jian Zhu Wei Zhang Xiulin Zhu 《Polymer Bulletin》2008,61(3):287-297
A novel reversible addition-fragmentation chain transfer (RAFT) reagent bearing triphenylamine (TPA)
group, 4-diphenylamino-dithiobenzoic acid benzyl ester (DDABE), was designed and synthesized. It was used
in the RAFT polymerizations of styrene (St) and methyl acrylate (MA) to prepare end-functionalized polymers.
The results of the polymerization showed that the RAFT polymerizations could be well controlled using DDABE
as the RAFT agent. Number-average molecular weight (Mn,GPC) increased linearly
with monomer conversion, and molecular weight distributions were relatively narrow (PDI<
1.50). The results of chain-extension reaction, 1H NMR spectra and UV/Vis
spectra confirmed that most of the polymers chains were end-capped by the functional triphenylamine
(TPA) groups. The effect of feed molar ratios of St/DDABE/AIBN on polymerization was investigated. 相似文献
17.
Jiang Minhong Gu Zhengfei Cheng Gang 《中国稀土学报(英文版)》2005,23(6):723-723
Polymer matrix RE-Fe giant magnetostrictire composite (GMPC) was prepared using bonding and magnetic field forming technique, and magnetostriction of samples was measured for different compressive stress. The experimental results show thai there is certain compressive effect in GMPC. And the influence of compressive stress on magnetostriction of sample was investigated. It offers essential reference for application and device design of GMPC. 相似文献
18.
Jiayong Cao Yu Zhu Jinsong Wang Wensheng Yin Guanghong Duan 《IEEE transactions on magnetics》2004,40(6):3490-3494
This paper investigates three kinds of permanent-magnet arrays used in planar motors with polarity centers distributed in the lattices of a matrix. The magnetic field of every kind of magnet array is analyzed by analytical methods. First, we give a Laplace equation of magnetic scalar potential and a series of boundary conditions. Then, we derive the analytical expressions of magnet field strength and magnet flux density in the air gap of each kind of magnet array by the method of separation of variables. Finally, we compare the three types of magnet arrays on the basis of the analytical solutions. 相似文献
19.
Web服务在信用信息工程中的应用 总被引:2,自引:2,他引:0
目前的社会信用信息工程中,许多的政府部门都建立了自己的信用信息数据库,但在政府各级部门数据库之间进行数据交流和共享存在着许多的问题,在许多地方,数据共享还是一片空白。Web服务技术是应用程序通过内联网或者因特网发布和利用软件服务的一种标准机制。利用WEB服务可以方便地实现不同系统之间的数据交换和集成。该文提出利用web服务技术来解决信用信息工程中的信息数据共享问题。并在此基础上提出利用WEB服务工作流技术将信用评估整合到电子商务过程,以实现可信用电子商务 相似文献
20.