全文获取类型
收费全文 | 2067篇 |
免费 | 72篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 48篇 |
综合类 | 4篇 |
化学工业 | 389篇 |
金属工艺 | 98篇 |
机械仪表 | 60篇 |
建筑科学 | 45篇 |
矿业工程 | 1篇 |
能源动力 | 221篇 |
轻工业 | 91篇 |
水利工程 | 32篇 |
石油天然气 | 3篇 |
无线电 | 206篇 |
一般工业技术 | 541篇 |
冶金工业 | 172篇 |
原子能技术 | 17篇 |
自动化技术 | 216篇 |
出版年
2023年 | 23篇 |
2022年 | 35篇 |
2021年 | 57篇 |
2020年 | 51篇 |
2019年 | 34篇 |
2018年 | 70篇 |
2017年 | 53篇 |
2016年 | 75篇 |
2015年 | 39篇 |
2014年 | 75篇 |
2013年 | 143篇 |
2012年 | 93篇 |
2011年 | 108篇 |
2010年 | 87篇 |
2009年 | 77篇 |
2008年 | 61篇 |
2007年 | 63篇 |
2006年 | 67篇 |
2005年 | 41篇 |
2004年 | 43篇 |
2003年 | 29篇 |
2002年 | 30篇 |
2001年 | 27篇 |
2000年 | 35篇 |
1999年 | 41篇 |
1998年 | 60篇 |
1997年 | 42篇 |
1996年 | 43篇 |
1995年 | 49篇 |
1994年 | 26篇 |
1993年 | 32篇 |
1992年 | 27篇 |
1991年 | 25篇 |
1990年 | 14篇 |
1989年 | 21篇 |
1988年 | 22篇 |
1987年 | 27篇 |
1986年 | 28篇 |
1985年 | 32篇 |
1984年 | 26篇 |
1983年 | 36篇 |
1982年 | 27篇 |
1981年 | 23篇 |
1980年 | 17篇 |
1979年 | 13篇 |
1978年 | 10篇 |
1977年 | 12篇 |
1976年 | 14篇 |
1974年 | 14篇 |
1973年 | 9篇 |
排序方式: 共有2144条查询结果,搜索用时 15 毫秒
1.
D.V.N. Harish A. Bharatish H.N. Narasimha Murthy B. Anand K.N. Subramanya 《Ceramics International》2021,47(3):3498-3513
Laser ablation of high-temperature ceramic coatings results in thermal residual stresses due to which the coatings fail by cracking and debonding. Hence, the measurement of such residual stresses during laser ablation process holds utmost importance from the view of performance of coatings in extreme conditions. The present research aims at investigating the effect of laser parameters such as laser pulse energy, scanning speed and line spacing on thermal residual stresses induced in tantalum carbide-coated graphite substrates. Residual stresses were measured using micro-Raman spectroscopy and correlated with Raman peak shifts. Transient thermal analysis was performed using COMSOL Multiphysics to model the single ablated track and residual stresses were reported at low, moderate and high pulse energy regimes. The results showed that the initial laser conditions caused higher tensile residual stresses. Moderate pulse energy regime comprised higher compressive residual stresses due to off centre overlapping of the laser pulses. Higher pulse energy (250 μJ), higher scanning speed (1000 mm/s) and moderate line spacing (20 μm) caused accumulation of tensile residual stresses during the final stage of laser ablation. The deviation of experimental residual stresses from COMSOL numerical model was attributed to unaccounted additional stresses induced during thermal spraying process and deformation potentials in the numerical model. 相似文献
2.
Jagadeesh Babu Sriramoju Murthy Muniyappa Navya Rani Marilingaiah Chetana Sabbanahalli Manjunath Shetty Ravi Mudike Chitrabanu C.P Prasanna D. Shivaramu Nagaraju G Kanchugarakoppal S. Rangappa Ananda Kumar C.S Dinesh Rangappa 《Ceramics International》2021,47(7):10314-10321
Application of brown titanium dioxide (TiO2-x) and its modified composite forms in the photocatalytic decomposition of organic pollutants in the environment is a promising way to provide solutions for environmental redemption. Herein, we report the synthesis of effective and stable TiO2-x nanoparticles with g-C3N4, RGO, and multiwalled carbon nanotubes (CNTs) using a simple hydrothermal method. Among all the as-synthesized samples, excellent photocatalytic degradation activity was observed for RGO-TiO2-x nanocomposite with high rate constants of 0.075 min?1, 0.083 min?1 and 0.093 min?1 for methylene blue, rhodamine-B, and rosebengal dyes under UV–Visible light irradiation, respectively. The altered bandgap (1.8 eV) and the large surface area of RGO-TiO2-x nanocomposite impacts on both absorption of visible light and efficiency of photogenerated charge electron (e?)/hole (h+) pair separation. This resulted in enhanced photocatalytic property of carbon-based TiO2-x nanocomposites. A systematic study on the influence of different carbon nanostructures on the photocatalytic activity of brown TiO2-x is carried out. 相似文献
3.
P. Sampath Brijesh Kakarla Raghava Reddy C. Venkata Reddy Nagaraj P. Shetti Raghavendra V. Kulkarni Anjanapura V. Raghu 《化学工程与技术》2020,43(7):1240-1248
Hydrogen fuel is a promising alternative to fossil fuels because of its energy content, clean nature, and fuel efficiency. However, it is not readily available. Most current producion processes are very energy intensive and emit carbon dioxide. Therefore, this article reviews technological options for hydrogen production that are eco-friendly and generate clean hydrogen fuel. Biological methods, such different fermentation processes and photolysis are discussed together with the required substrates and the process efficiency. 相似文献
4.
Mani Balamurugan Hui‐Yun Jeong Venkata Surya Kumar Choutipalli Jung Sug Hong Hongmin Seo Natarajan Saravanan Jun Ho Jang Kang‐Gyu Lee Yoon Ho Lee Sang Won Im Venkatesan Subramanian Sun Hee Kim Ki Tae Nam 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(25)
The electrochemical reduction of carbon dioxide (CO2) to hydrocarbons is a challenging task because of the issues in controlling the efficiency and selectivity of the products. Among the various transition metals, copper has attracted attention as it yields more reduced and C2 products even while using mononuclear copper center as catalysts. In addition, it is found that reversible formation of copper nanoparticle acts as the real catalytically active site for the conversion of CO2 to reduced products. Here, it is demonstrated that the dinuclear molecular copper complex immobilized over graphitized mesoporous carbon can act as catalysts for the conversion of CO2 to hydrocarbons (methane and ethylene) up to 60%. Interestingly, high selectivity toward C2 product (40% faradaic efficiency) is achieved by a molecular complex based hybrid material from CO2 in 0.1 m KCl. In addition, the role of local pH, porous structure, and carbon support in limiting the mass transport to achieve the highly reduced products is demonstrated. Although the spectroscopic analysis of the catalysts exhibits molecular nature of the complex after 2 h bulk electrolysis, morphological study reveals that the newly generated copper cluster is the real active site during the catalytic reactions. 相似文献
5.
V S R Murthy 《Bulletin of Materials Science》1993,16(2):87-108
Research and development efforts on high-temperature, oxidation-resistant fibres have increased over the past decade due to
the demand for light-weight, stiff and strong composite materials in aerospace applications. Varieties of ‘high-performance’,
continuous, non-oxide fibres with low-density, high tensile strength and tensile modulus have been developed either from organic
precursors or via chemical vapour deposition for fabrication of ceramic matrix composites. Fibres derived from polymer precursors
(e.g. Nicalon, Tyranno, HPZ) are small in diameter (compared to CVD monofilaments) and are ideally suited for ceramic composites.
Processing, microstructural stability and mechanical properties of these newly developed SiC and Si3N4 base fibres are briefly reviewed in this paper. 相似文献
6.
7.
8.
9.
Acoustic Emission (AE) signals, which are electrical version of acoustic emissions, are usually analysed using a set of signal
parameters. The major objective of signal analysis is to study the characteristics of the sources of emissions. Peak amplitude(P
a
) and rise time(R
t
) are two such parameters used for source characterization. In this paper, we theoretically investigate the efficiency ofP
a
andR
t
to classify and characterize AE sources by modelling the input stress pulse and transducer. Analytical expressions obtained
forP
a
andR
t
clearly indicate their use and efficiency for source characterization. It is believed that these results may be of use to
investigators in areas like control systems and signal processing also 相似文献
10.
Acoustic emission technique for leak detection in an end shield of a pressurised heavy water reactor
P. Kalyanasundaram T. Jayakumar B. Raj C.R.L. Murthy A. Krishnan 《Nuclear Engineering and Design》1989,116(2)
This paper discusses the successful application of the Acoustic Emission Technique (AET) for detection and location of leak paths present on the inaccessible side of an end shield of a Pressurised Heavy Water Reactor (PHWR). The methodology was based on the fact that air and water leak AE signals have different characteristic features. Baseline data was generated from a sound end-shield of a PHWR for characterizing the background noise. A mock up end-shield system with saw cut leak paths was used to verify the validity of the methodology. It was found that air leak signals under pressurisation (as low as 3 psi) could be detected by frequency domain analysis. Signals due to air leaks from various locations of a defective end-shield were acquired and analysed. It was possible to detect and locate leak paths. Presence of detected leak paths were further confirmed by alternate test. 相似文献