全文获取类型
收费全文 | 717篇 |
免费 | 53篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 16篇 |
综合类 | 1篇 |
化学工业 | 144篇 |
金属工艺 | 25篇 |
机械仪表 | 22篇 |
建筑科学 | 29篇 |
矿业工程 | 1篇 |
能源动力 | 33篇 |
轻工业 | 28篇 |
水利工程 | 4篇 |
石油天然气 | 4篇 |
武器工业 | 1篇 |
无线电 | 118篇 |
一般工业技术 | 161篇 |
冶金工业 | 35篇 |
原子能技术 | 24篇 |
自动化技术 | 126篇 |
出版年
2023年 | 16篇 |
2022年 | 26篇 |
2021年 | 31篇 |
2020年 | 36篇 |
2019年 | 25篇 |
2018年 | 42篇 |
2017年 | 37篇 |
2016年 | 44篇 |
2015年 | 24篇 |
2014年 | 36篇 |
2013年 | 41篇 |
2012年 | 40篇 |
2011年 | 63篇 |
2010年 | 32篇 |
2009年 | 42篇 |
2008年 | 31篇 |
2007年 | 22篇 |
2006年 | 14篇 |
2005年 | 13篇 |
2004年 | 8篇 |
2003年 | 8篇 |
2002年 | 11篇 |
2001年 | 11篇 |
2000年 | 3篇 |
1999年 | 7篇 |
1998年 | 17篇 |
1997年 | 8篇 |
1996年 | 8篇 |
1995年 | 11篇 |
1994年 | 10篇 |
1993年 | 9篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 6篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 1篇 |
排序方式: 共有772条查询结果,搜索用时 15 毫秒
71.
本文针对我省正在开展的加强灌溉农业三期WUA项目建设中量测水技术及设备引进选型进行了探讨,提出了初步设计思路. 相似文献
72.
Dung The Nguyen Dong-Joo Kim Myoung Gi So Kyo-Seon Kim 《Advanced Powder Technology》2010,21(2):111-118
Gold particle nucleation and growth were analyzed systematically by UV–vis, ELS and TEM measurements. The gold seed particles ranging from 14.3 nm to 20.3 nm were prepared with monodisperse size distribution by citrate reduction reaction of various initial HAuCl4 concentrations. Gold nanoparticles of different sizes were made by the seed-mediated growth process. In the first stage of seed-mediated growth, most of gold precursors were used for the growth of seed particles, but, further supply of gold precursors promotes the nucleation of small particles and decreases the average particle diameters while the polydispersity of particles increases. This research can be used as basic data to prepare gold nanoparticles with specific properties for different applications. 相似文献
73.
Phuong Pham Thi Thuy Phuong Nguyen Nguyen Kumar P. Senthil Duy Nguyen Phuc Hoang Van Le Quyet Ngoc Le Thi Bao Jalil A. A. Rajendran Saravanan Cheng Chin Kui Nguyen Thanh-Huong Dinh Minh Tuan Nguyen Vo Dai-Viet N. 《Topics in Catalysis》2023,66(1-4):41-52
Topics in Catalysis - CO2 reforming of methanol for producing hydrogen was experimentally carried out in a fixed-bed reactor on 10%Ni/SiO2. The 10%Ni/SiO2 was completely reduced during H2... 相似文献
74.
75.
Experimental characterization of thermo-oxidation-induced shrinkage and damage in polymer-matrix composites 总被引:1,自引:0,他引:1
This paper focuses on the experimental characterization of thermo-oxidation in carbon-fiber-reinforced polymers (CFRPs) exposed to “high” temperatures (up to 150 °C) and “high” oxygen pressures (up to 5 bars), at the microscopic scale. Unidirectional IM7/977-2 composite specimens were aged at 150 °C under atmospheric air and under oxygen pressure (1.7 bars and 5 bars): periodic tests were carried out to characterize degradation phenomena after different aging times. The thermo-oxidation-induced resin shrinkage and fiber/matrix debonding were measured on the CFRP sample surface by confocal interferometric microscopy (CIM) and scanning electron microscopy (SEM). The results show that thermo-oxidation-induced degradation strongly depends on aging time, distance between fibers and partial oxygen pressure. 相似文献
76.
77.
Seong Min Oh Kyung Min Oh Trung Dung Dao Hyung‐il Lee Han Mo Jeong Byung Kyu Kim 《Polymer International》2013,62(1):54-63
Graphene prepared by the thermal reduction of graphite oxide was modified by reactions with methanol or 1‐butanol using aqueous HBF4 solution as a catalyst. Results showed that the reaction created hydroxyl groups on the graphene and at the same time reduced the number of defects. Gravimetry, thermogravimetry, X‐ray photoelectron spectroscopy and Fourier transform infrared spectroscopy showed that the alcohols had reacted with epoxide groups on graphene. Raman spectroscopy showed that the defects in the graphene were repaired through other accompanying reactions. The reinforcing effect of graphene, observed in the tensile properties and the shape memory behavior of graphene/polyurethane composites, was increased when the graphene was modified with methanol. However, decreases in density and glass transition temperature were evident for the composites made with alcohol‐modified graphene. These results show that the newly created hydroxyl groups on graphene produce effective covalent bonds with the polyurethane chains of the matrix; however, the increased number of bonds restricts the rearrangement of the matrix molecules for dense packing. The covalent bonds between graphene and polyurethane chains enhanced shape recoverability and reduced the hysteresis brought about by repeated thermomechanical cycles. Copyright © 2012 Society of Chemical Industry 相似文献
78.
79.
Tuan Pham Dinh Perrault H. Calabrese P. Eberhard A. Benchetrit G. 《IEEE transactions on bio-medical engineering》1999,46(9):1161-1165
A statistical method with the advantages of 1) enabling graphical representation of within-respiratory cycle heart rate variations, 2) detecting the presence of respiratory sinus arrhythmia (RSA) in a moving window, and 3) providing breath-by-breath RSA amplitude and phase obtained from the fitting of a sinusoid to the instantaneous relative heart rate is presented. 相似文献
80.
We present a unified approach to the construction of multidimensional trellis codes that have small constellation expansion ratio (CER) and small peak-to-average power ratio (PAR) and hence are of high bandwidth efficiency. In the approach, we extend Wei's (1987) construction to dimensionalities other than a power of two and propose a low-complexity encoder. We also present a general partition technique that gives geometrically uniform partitions with a good distance profile. The proposed method can generate many good codes including previously reported Ungerboeck codes, Gallager-Calderbank-Sloane codes, and Wei codes with quadrature amplitude modulation signals. Some newly discovered six-dimensional trellis codes are compared with these known codes on their CER, PAR, effective coding gain, and encoder/decoder complexities. 相似文献