全文获取类型
收费全文 | 782篇 |
免费 | 45篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 4篇 |
综合类 | 7篇 |
化学工业 | 201篇 |
金属工艺 | 21篇 |
机械仪表 | 15篇 |
建筑科学 | 21篇 |
能源动力 | 56篇 |
轻工业 | 99篇 |
水利工程 | 7篇 |
石油天然气 | 14篇 |
无线电 | 84篇 |
一般工业技术 | 151篇 |
冶金工业 | 34篇 |
自动化技术 | 122篇 |
出版年
2024年 | 4篇 |
2023年 | 18篇 |
2022年 | 44篇 |
2021年 | 88篇 |
2020年 | 54篇 |
2019年 | 41篇 |
2018年 | 61篇 |
2017年 | 30篇 |
2016年 | 45篇 |
2015年 | 29篇 |
2014年 | 42篇 |
2013年 | 66篇 |
2012年 | 43篇 |
2011年 | 53篇 |
2010年 | 26篇 |
2009年 | 27篇 |
2008年 | 23篇 |
2007年 | 22篇 |
2006年 | 11篇 |
2005年 | 12篇 |
2004年 | 16篇 |
2003年 | 12篇 |
2002年 | 6篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 6篇 |
1997年 | 4篇 |
1996年 | 7篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1991年 | 5篇 |
1990年 | 1篇 |
1988年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1956年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有836条查询结果,搜索用时 15 毫秒
41.
Farrah Farooq 《Expert Systems》2013,30(5):451-472
In order to explore the most current information and react faster to changing business conditions, organizations consider real‐time data warehousing a powerful technique to achieve operational business intelligence (BI). We propose in this paper a novel real‐time data warehouse (RTDW) framework based on the virtualization concept. Our approach introduces a conceptual modelling technique, known as ring modelling, for real‐time data management and multidimensional analysis. This technique produces a flexible semi‐structured data model that accommodates unknown business process data and relationships as they evolve, handles schema changes and aggregate‐management efficiently, and scales well with the large size of increasing data volumes. With the help of a telecommunication business example, We evaluated our proposed approach in an extensive experimental study where we compared our approach Ring Model with existing structured multidimensional conceptual models (MCMs), i.e. relational OLAP and multidimensional OLAP, and with semi‐structured MCM, i.e. XML Cubes, in terms of scalability, data storage estimations, data updates loading time, and query response times. Our performance results show that encouraging speedups are achieved. 相似文献
42.
Z Abbas AH Khan SM Jafri SS Hamid SH Shah S Abid JA Qureshi 《Canadian Metallurgical Quarterly》1997,12(11):703-706
The authors compared in a controlled clinical study two groups of patients after a first renal transplantation treated by triple drug immunosuppressive therapy. In a group of 31 patients the triple combination comprised Sandimmune Neoral. In the control group there were 30 patients who received Sandimmune. No differences were found between the two groups as regards the effectiveness of this treatment and the authors did not confirm a lower incidence of rejections described in patients treated with Sandimmune Neoral. They confirmed, however, a lower interindividual variability of Cy-A levels assessed specifically in patients treated with Sandimmune Neoral. 相似文献
43.
Musrat Ali Urooj Haroon Maria Khizar Hassan Javed Chaudhary Muhammad Farooq Hussain Munis 《Microscopy research and technique》2021,84(1):101-110
Citrus is the leading fruit crop of Pakistan and exported to different parts of the world. Due to suitable weather condition, this crop is affected by different biotic factors which seriously deteriorate its quality and quantity. During the months of November 2018 to January 2019, citrus brown rot symptoms were recurrently observed on sweet oranges in National Agricultural Research Centre (NARC), Islamabad. Causal agent of citrus brown rot was isolated, characterized, and identified as Fusarium oxysporum. For environment‐friendly control of this disease, leaf extract of Azadirachta indica was used for the green synthesis of iron oxide (Fe2O3) nanoparticles. These nanoparticles were characterized before their application for disease control. Fourier transform infrared spectroscopy (FTIR) of these synthesized nanoparticles described the presence of stabilizing and reducing compounds like alcohol, phenol, carboxylic acid, and alkaline and aromatic compounds. X‐Ray diffraction (XRD) analysis revealed the crystalline nature and size (24 nm) of these nanoparticles. Energy dispersive X‐Ray (EDX) analysis elaborated the presence of major elements in the samples. Scanning electron microscopy (SEM) confirmed the spinal shaped morphology of prepared nanoparticles. Successfully synthesized nanoparticles were evaluated for their antifungal potential. Different concentrations of Fe2O3 nanoparticles were used and maximum mycelial inhibition was observed at 1.0 mg/ml concentration. On the basis of these findings, it could be concluded that Fe2O3 nanoparticles, synthesized in the leaf extract of A. indica, can be successfully used for the control of brown rot of sweet oranges. 相似文献
44.
Mohamed Abid Author Vitae 《Computers & Electrical Engineering》2007,33(4):231-232
45.
Serrano-Guisan S di Domenicantonio G Abid M Abid JP Hillenkamp M Gravier L Ansermet JP Félix C 《Nature materials》2006,5(9):730-734
The emerging field of spintronics explores the many possibilities offered by the prospect of using the spin of the electrons for fast, nanosized electronic devices. The effect of magnetization acting on a current is the essence of giant or tunnel magnetoresistance. Although such spintronics effects already find technological applications, much of the underlying physics remains to be explored. The aim of this article is to demonstrate the importance of spin mixing in metallic nanostructures. Here we show that magnetic clusters embedded in a metallic matrix exhibit a giant magnetic response of more than 500% at low temperature, using a recently developed thermoelectric measurement. This method eliminates the dominating resistivity component of the magnetic response and thus reveals an intrinsic spin-dependent process: the conduction-electron spin precession about the exchange field as the electron crosses the clusters, giving rise to a spin-mixing mechanism with strong field dependence. This effect appears sensibly only in the smallest clusters, that is, at the level of less than 100 atoms per cluster. 相似文献
46.
Qasim Ali Farooq Anwar Muhammad Ashraf Nazamid Saari Rashida Perveen 《International journal of molecular sciences》2013,14(1):818-835
This study was carried out to appraise whether or not the exogenous application of a potential osmoprotectant, proline, could ameliorate the adverse effects of drought stress on maize seed and seed oil composition, as well as oil antioxidant activity. Water stress reduced the kernel sugar, oil, protein and moisture contents and most of the seed macro- and micro-elements analyzed in both maize cultivars but it increased the contents of seed fiber and ash. Water stress increased the oil oleic acid content with a subsequent decrease in the amount of linoleic acid, resulting in an increased oil oleic/linoleic ratio for both maize cultivars. However, no variation was observed in oil stearic and palmitic acids content due to water stress. A considerable drought induced an increase in seed oil α-, γ-, δ- and total tocopherols and flavonoids were observed in both maize cultivars. However, oil phenolic and carotenoid content as well as 1,1-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging activity decreased. Foliar-applied proline significantly increased the content of seed sugar, oil, protein, moisture, fiber and ash in both maize cultivars under well irrigated and water deficit conditions. Furthermore, exogenous application of proline increased the oil oleic and linoleic acid contents. The concentrations of antioxidant compounds namely phenolics, carotenoids, flavonoids and tocopherols estimated in the seed oil increased due to foliar-applied proline under water deficit conditions that was positively correlated with the enhanced oil DPPH free radical scavenging activity. Moreover, the increase in the contents of these antioxidant compounds and oil antioxidant activity due to the foliar application of proline was noted to be more pronounced under water deficit conditions. 相似文献
47.
Hassan Zaheer-ul- Munir Tariq Ahmad Naseeb Hashmi M. Ibad Ullah Ali Yasir Tahir Muhammad Bilal Hussain Abid Rehman Jalil ur Wattoo Abdul Ghafar Alrobei Hussein 《Journal of Superconductivity and Novel Magnetism》2021,34(12):3237-3242
Journal of Superconductivity and Novel Magnetism - Silver-substituted Fe–Ni nano invar alloy is a new and innovative field of research due to their interesting invar, magnetic and electrical... 相似文献
48.
Jagtar Singh Mohammad Farooq Wani 《International Journal of Applied Ceramic Technology》2021,18(5):1853-1862
Tribological properties of Ti3SiC2 ceramic and Ti3SiC2/GNP composite were investigated using fretting sliding against Si3N4 ball counter body at a load of 50 N for a sliding distance of 900 m, under non-textured lubricated (NTL), textured lubricated (TL) condition, and textured lubricated high temperature (TLHT). This paper presents the influence of laser surface texturing (LST) on Ti3SiC2 and its graphene nanoplatelets (GNP) reinforced composite established through spark plasma sintering (SPS), tested under fretting wear conditions. The coefficient of friction and wear rate of Ti3SiC2 and its graphene nanoplatelets reinforced composites were incontrovertibly enhanced with laser surface texturing as compared to non-textured Ti3SiC2 and its GNP composite. The TL surface of Ti3SiC2 composite reinforced with 15% GNP showed the lowest COF and wear rate. Almost negligible changes were observed for TLHT tests. The LST proved to an efficient technique for enhancing the friction and wear properties of Ti3SiC2 and Ti3SiC2/GNP composite. 相似文献
49.
50.
移动代理技术已经成为设计、实现分布式应用的一种极具前景的技术,现有许多移动代理系统已经在研究及商业领域得以实现.但是移动代理系统至今仍然没有得到很广泛的应用,其原因除了使用移动代理系统所涉及的安全性问题之外,另一个主要因素就是缺少一个对移动代理系统性能进行量化评价的基准.本文对于现有的能够对各种不同移动代理系统进行量化评测的基准进行综述,并且讨论哪些因素会对移动代理架构性能产生根本的影响. 相似文献