全文获取类型
收费全文 | 170篇 |
免费 | 14篇 |
专业分类
电工技术 | 10篇 |
化学工业 | 42篇 |
金属工艺 | 3篇 |
机械仪表 | 8篇 |
建筑科学 | 2篇 |
能源动力 | 11篇 |
轻工业 | 18篇 |
水利工程 | 1篇 |
无线电 | 9篇 |
一般工业技术 | 54篇 |
冶金工业 | 5篇 |
自动化技术 | 21篇 |
出版年
2024年 | 2篇 |
2023年 | 2篇 |
2022年 | 10篇 |
2021年 | 9篇 |
2020年 | 17篇 |
2019年 | 13篇 |
2018年 | 13篇 |
2017年 | 16篇 |
2016年 | 12篇 |
2015年 | 9篇 |
2014年 | 8篇 |
2013年 | 7篇 |
2012年 | 6篇 |
2011年 | 6篇 |
2010年 | 6篇 |
2009年 | 9篇 |
2008年 | 2篇 |
2007年 | 3篇 |
2006年 | 3篇 |
2005年 | 2篇 |
2004年 | 1篇 |
2003年 | 5篇 |
2002年 | 2篇 |
2001年 | 1篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1980年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 2篇 |
排序方式: 共有184条查询结果,搜索用时 15 毫秒
11.
Mohd. Hashim Sagar E. Shirsath S.S. Meena Pramod Bhatt R.K. Kotnala Shalendra Kumar Ravi Kumar Dachepalli Ravinder Alimuddin 《Ceramics International》2014
The Cr3+ ions doped multi-oxide ZnFe2−xCrxO4 ferrite nanoparticles have been synthesized by chemical co-precipitation method. Site occupancies of Zn2+, Cr3+ and Fe3+ ions were analyzed using X-ray diffraction data and Buerger's method. The effect of the constituent phase variation on the magnetic hysteresis behavior was examined by saturation magnetization which decreases with the increase in Cr3+ content in place of Fe3+ ions at octahedral B-site. Typical blocking temperature (TB) around 90 K was observed by zero field cooling and field cooling magnetization study. Room temperature Mössbauer spectra show two paramagnetic doublets (tetrahedral and octahedral sites). The isomer shifts of both doublets decrease whereas quadrupole splitting and relative area of tetrahedral A-site increases with increasing Cr3+ substitution. The dielectric constant (measured on compositions x=0, 0.4, 0.8 and 1.0) increases when the temperature increases as in the semiconductor. This behavior is attributed to the hopping of electrons between Fe2+ and Fe3+ ions with a thermal activation. 相似文献
12.
Rekha Agrawal Jyoti Shah Govind Gupta Ritu Srivastava Chhemendra Sharma Ravinder Kotnala 《应用聚合物科学杂志》2020,137(48):49566
A facile and eco-friendly synthesis of polypyrrole from monomer pyrrole using nominal amount of ferric chloride hexahydrate (FeCl3.6H2O) oxidant in aqueous solution by chemically oxidative polymerization method has been reported. The use of aqueous solvent and ferric chloride hexahydrate salt in polypyrrole synthesis have an eco-friendly route favorable for the production of polypyrrole in large quantities. The synthesized polypyrrole samples exhibit good electrical conductivity (2 S/cm) and yield of 80% for reaction time of 8 hr at 5°C. Quality and properties of polypyrrole samples have been thoroughly investigated with varying reaction time and temperature while other synthesis parameters like molar ratio of oxidant to monomer, oxidant concentration, and solvent were kept constant. X-ray diffraction analysis of polypyrrole with a shorter reaction time shows the presence of iron oxide (Fe2O3) peaks. The complete reaction may not occur at shorter reaction times due to which residual ferric ions converted into Fe2O3. X-ray photoelectron spectroscopy measurement of polypyrrole also confirms the formation of Fe2O3. Appropriate selection of reaction time and temperature produced pure phase polypyrrole with high yield and good conductivity. Synthesized polypyrrole by our eco-friendly and cost-effective technique exhibits prominent electromagnetic shielding effectiveness value of 30 dB in the X-band (8–12 GHz). 相似文献
13.
14.
A. V. Ramana Reddy G. Ranga Mohan D. Ravinder B. S. Boyanov 《Journal of Materials Science》1999,34(13):3169-3176
The dielectric constant () and complex dielectric constant () of zinc substituted cobalt ferrites have been measured at room temperature in the high frequency range 100 kHz to 1 MHz. The values of dielectric loss tangent (tan ) have been computed from and . Plots of dielectric constant () versus frequency show a normal dielectric behaviour of the spinel ferrites. The frequency dependence of dielectric loss tangent (tan ) is found to be abnormal, giving a peak at certain frequency for all the ferrites under investigation. A qualitative explanation is given for the composition and frequency dependence of the dielectric constant and dielectric loss tangent. The dielectric constant for these mixed ferrites is approximately inversely proportional to the square root of the resistivity. A plot of dielectric constant versus temperature shows a transition near the Curie temperature. An attempt is made to explain the possible mechanism for this observation. 相似文献
15.
This article extends the analysis of an earlier paper by the authors for a single product to lot size determination for manufacturing cycles of multiple products. The effects of production breaks, learning interactions due to commonality of tasks and different learning rates for products are considered in the formulation of an equation for the average production time per unit. The equation is applied to an equal lot size per product model. An analysis of a model restricted to equal production intervals per product per cycle is also presented. A sample problem is solved to demonstrate the application of the effects of learning to multiple product lot size determination. 相似文献
16.
C.P. Kaushik Ravinder Tuteja Namrata Kaushik J.K. Sharma 《Chemical engineering journal (Lausanne, Switzerland : 1996)》2009,155(1-2):234-240
The work is carried out to minimize the organic chemical load (unexhausted dye contents) in direct dyes effluent using low cost adsorbents. The studies are made with different direct dyes, i.e. Direct Red 28, Direct Yellow 12, Direct Orange 26 and Direct Blue 1 with various adsorbents. Three different bio/natural materials have been selected as adsorbents. These includes, Sugarcane bagasse pith (SB), Saw dust (SD)—the plant origin products, and Brick powder (BP)—a silica based material obtained from earth's crust on thermal heating. These substances are almost discarded waste products with the possibility of use as adsorbents. Experimental work for the dye removal from the effluent by activated charcoal (AC) has also been carried out and the results are compared with other adsorbents. The amount of unexhausted organic dye present in the effluent is measured as chemical oxygen demand (COD) before and after the treatment. Adsorbent Sugarcane bagasse pith shows good performance as compared to Saw dust and Brick powder. For understanding the behaviour of adsorbents Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) has also been carried out. 相似文献
17.
Silicon - In this article, a Heterogeneous Gate-Dielectric Nanosheet Tunnel Field Effect Transistor (HD-NSH-TFET) with three channels is investigated using the 3-D Visual TCAD simulator. The HD... 相似文献
18.
Ravinder Nath 《Behaviour & Information Technology》1992,11(1):24-31
More and more organizations are seeking innovative ways to use information technology (IT) for strategic advantage. One way to gain this competitive edge is by differentiating the services provided to customers. This paper provides a framework to identify areas ripe for the implementation of IT to enhance and improve customer service. The framework is based upon the examination of the existing service delivery system of an organization and how applications of IT might change the interfaces among the various players (customers, employees, etc.) in the service delivery system. Further, examples are presented to illustrate how some organizations have achieved superior service quality by creatively utilizing simple IT tools. 相似文献
19.
20.
Niels D. Naimon Jerzy Walczyk James S. Babb Oleksandr Khegai Xuejiao Che Leeor Alon Ravinder R. Regatte Ryan Brown Prodromos Parasoglou 《Magma (New York, N.Y.)》2017,30(3):281-289