全文获取类型
收费全文 | 2139篇 |
免费 | 198篇 |
国内免费 | 43篇 |
专业分类
电工技术 | 56篇 |
综合类 | 53篇 |
化学工业 | 543篇 |
金属工艺 | 112篇 |
机械仪表 | 97篇 |
建筑科学 | 126篇 |
矿业工程 | 10篇 |
能源动力 | 181篇 |
轻工业 | 297篇 |
水利工程 | 36篇 |
石油天然气 | 41篇 |
武器工业 | 6篇 |
无线电 | 107篇 |
一般工业技术 | 304篇 |
冶金工业 | 93篇 |
原子能技术 | 30篇 |
自动化技术 | 288篇 |
出版年
2024年 | 11篇 |
2023年 | 35篇 |
2022年 | 80篇 |
2021年 | 124篇 |
2020年 | 75篇 |
2019年 | 80篇 |
2018年 | 102篇 |
2017年 | 101篇 |
2016年 | 123篇 |
2015年 | 84篇 |
2014年 | 106篇 |
2013年 | 247篇 |
2012年 | 118篇 |
2011年 | 132篇 |
2010年 | 123篇 |
2009年 | 111篇 |
2008年 | 80篇 |
2007年 | 76篇 |
2006年 | 52篇 |
2005年 | 32篇 |
2004年 | 44篇 |
2003年 | 43篇 |
2002年 | 91篇 |
2001年 | 77篇 |
2000年 | 36篇 |
1999年 | 29篇 |
1998年 | 27篇 |
1997年 | 11篇 |
1996年 | 12篇 |
1995年 | 17篇 |
1994年 | 17篇 |
1993年 | 10篇 |
1992年 | 11篇 |
1991年 | 9篇 |
1990年 | 3篇 |
1988年 | 3篇 |
1986年 | 2篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1975年 | 3篇 |
1971年 | 2篇 |
1930年 | 2篇 |
1918年 | 2篇 |
1910年 | 1篇 |
排序方式: 共有2380条查询结果,搜索用时 0 毫秒
1.
Sinan Zhang Yadonga Zhao Xueshuang Yao Zhenhong Zheng Chuyao Zheng Zhuo Jiang 《International Journal of Food Science & Technology》2022,57(7):4245-4253
Ripe carambolas are hard to store and transport, while freeze-dried ones are easy to store. However, its long production time leads to higher costs. This study shows that high hydrostatic pressure (HHP) treatment could shorten the freeze-drying time of carambola slices. After HHP treatment (25–250 MPa), the drying time of the fresh sample can be shortened by 33.3–44.4% and the distribution of water and pigment in tissues is much uniform. With the increment of the pressure, 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical scavenging rate are increased. At 250 MPa, the total phenolic content (TPC) increased from 11.34 to 13.36 mg GAE g−1, and the total flavonoid content (TFC) of the control sample was increased from 10.77 to 12.73 mg RE g−1. Compared with the untreated sample, HHP treatment can enhance the flavour and shorten the freeze-drying time. This work guides the application of HHP technology for drying food processing. 相似文献
2.
Precipitation of calcium deficient hydroxyapatite nanoparticles in an environmentally benign manner by using only dilute solutions of calcium hydroxide and phosphoric acid without pH adjustment and addition of other chemicals, and water, being the only by-product was investigated by using continuous flow Vortex Reactor (VR) and Semi-Batch Reactor (SBR). The effect of hydrodynamics by changing the Reynolds number of the jets providing residence times of 8.4 ms to 4.37 s for VR, and by changing the stirrer speed between 100 rpm (Re = 2656) and 1000 rpm (Re = 26560) for SBR, on the particle size, particle size distribution, and morphology of the particles was investigated for both systems. It has been shown that it is possible to produce pure phase hydroxyapatite nanoparticles in the desired morphology by changing production system, without resorting to additives. While VR produced rod-like particles with the crystallite size around 4 nm, SBR produced spherical particles with the crystallite size of around 5 nm. 相似文献
3.
Journal of Low Temperature Physics - This study modeled and investigated the magnetocaloric effect in Ni2MnGa Heusler alloy characterized by its magnetic entropy change (ΔSm) and its... 相似文献
4.
5.
该文利用色集事先分配法、构造染色法、反证法探讨了完全三部图K4,4,p (p≥1008)的点可区别IE-全染色问题,确定了K4,4,p (p≥1008)的点可区别IE-全染色数。 相似文献
6.
This paper presents the mass transfer results from an impinging liquid jet to a rotating disk. The mass transfer coefficients were measured using the electrochemical limiting diffusion current technique (ELDCT). Rotational Reynolds number (Rer) in the range of 3.4 × 104–1.2 × 105, jet Reynolds number (Rej) 1.7 × 104–5.3 × 104 and non-dimensional jet-to-disk spacing (H/d) 2–8 were taken into consideration as parameters. It was found that the jet impingement resulted in a substantial enhancement in the mass transfer compared to the case of the rotating disk without jet. 相似文献
7.
This study concerns how user training on newly introduced computer application programs is carried out. Questionnaire data from the computer managers of 265 Swedish companies were analysed. The results show that formal training, i.e., teacher-directed group instruction, and self-studies using instruction manuals represented nearly two-thirds of all reported training forms. For the most recently introduced program, classes (group instruction) with simultaneous computer exercises was the form of formal training that was nearly always used. When formal training was given it was compulsory in over half of the cases. However, substitutes for users attending a training course were only provided by the company in very few of these cases. The implications of these findings for effective user training are discussed. 相似文献
8.
Metin Kul Muhsin Zor Ahmet Senol Aybek Sinan Irmak Evren Turan 《Solar Energy Materials & Solar Cells》2007,91(10):882-887
The CdO:F samples have been deposited onto microscope glass substrates at 250 °C by ultrasonic spray pyrolysis method. With the incorporation of fluorine into CdO, the direct optical transition has shifted towards the shorter wavelengths, and the transparency of the material has increased at a given wavelength above the fundamental absorption edge. The shift in the absorption edge is explained by means of the Moss–Burstein effect, which is also supported with the results of the current–voltage characteristics. Here, a correlation has been established between the band broadening and the increase in conductivity due to the increase in carrier density. 相似文献
9.
A method for the time suboptimal control of an industrial manipulator from an initial position and orientation to a final
position and orientation as it moves along a specified path is proposed. Nonlinear system equations that describe the manipulator
motion are linearized at each time step along the path. A method which gives the control inputs (joint angular velocities)
for time suboptimal control of the manipulator is developed. In the formulation, joint angular velocity and acceleration limitations
are also taken into consideration. A six degree of freedom elbow type manipulator is used in numerical examples to verify
the method developed. 相似文献
10.
The reduction of nitric oxide with ammonia on an unsupported iron oxide catalyst has been studied in a continuous-flow recycle reactor using simulated flue gas. The responses of the employed reactor system to step and pulse inputs of tracer indicate that the system could be regarded as a continuous stirred tank reactor (CSTR). Preliminary tests were carried out to determine the effect of temperature and particle size on the measured reaction rates. Additional experiments were performed in order to study the influence of oxygen and water concentration on these rates. A gas chromatographic system has been developed to analyze the gas components NO, N2O, NO2, NH3, H2O, O2, CO2 and N2. In addition, the concentrations of NO and NO2 were measured with a nondisperse infrared (NDUV/NDIR) analyzer. 相似文献