全文获取类型
收费全文 | 3460篇 |
免费 | 89篇 |
国内免费 | 16篇 |
专业分类
电工技术 | 58篇 |
综合类 | 8篇 |
化学工业 | 672篇 |
金属工艺 | 120篇 |
机械仪表 | 108篇 |
建筑科学 | 51篇 |
矿业工程 | 15篇 |
能源动力 | 181篇 |
轻工业 | 194篇 |
水利工程 | 30篇 |
石油天然气 | 6篇 |
无线电 | 555篇 |
一般工业技术 | 853篇 |
冶金工业 | 342篇 |
原子能技术 | 28篇 |
自动化技术 | 344篇 |
出版年
2024年 | 13篇 |
2023年 | 44篇 |
2022年 | 82篇 |
2021年 | 165篇 |
2020年 | 82篇 |
2019年 | 84篇 |
2018年 | 123篇 |
2017年 | 90篇 |
2016年 | 102篇 |
2015年 | 75篇 |
2014年 | 114篇 |
2013年 | 213篇 |
2012年 | 135篇 |
2011年 | 191篇 |
2010年 | 148篇 |
2009年 | 158篇 |
2008年 | 145篇 |
2007年 | 115篇 |
2006年 | 110篇 |
2005年 | 88篇 |
2004年 | 68篇 |
2003年 | 68篇 |
2002年 | 57篇 |
2001年 | 61篇 |
2000年 | 64篇 |
1999年 | 54篇 |
1998年 | 105篇 |
1997年 | 58篇 |
1996年 | 52篇 |
1995年 | 51篇 |
1994年 | 63篇 |
1993年 | 59篇 |
1992年 | 54篇 |
1991年 | 58篇 |
1990年 | 45篇 |
1989年 | 28篇 |
1988年 | 29篇 |
1987年 | 32篇 |
1986年 | 30篇 |
1985年 | 23篇 |
1984年 | 32篇 |
1983年 | 21篇 |
1982年 | 27篇 |
1981年 | 13篇 |
1980年 | 24篇 |
1979年 | 21篇 |
1978年 | 10篇 |
1977年 | 18篇 |
1976年 | 23篇 |
1973年 | 8篇 |
排序方式: 共有3565条查询结果,搜索用时 15 毫秒
101.
This paper examines the anticorrosion characteristics of three different benzimidazole derivatives towards mild steel in 0.5?M hydrochloric acid at temperature ranges from 303 to 323?K. The benzimidazole derivatives used for the screening studies are 2-(2-methyl-1H-benzimidazol-1-yl) acethydrazide (EMBAH), 2-(2-ethyl-1H-benzimidazol-1-yl) acethydrazide (EEBAH) and 2-(2-propyl-1H-benzimidazol-1-yl) acethydrazide (EPBAH). The corrosion inhibition was investigated by weight loss, electrochemical impedance spectroscopy and potentiodynamic polarization studies. The adsorption interaction between metal and inhibitor followed Langmuir adsorption isotherm. The Gibb’s free energy values clarify the spontaneous nature of adsorption process. The temperature dependence of inhibition efficiency was explained by considering thermodynamic parameters of adsorption and kinetic parameters of corrosion. These inhibitors showed good efficiency at lower as well as moderately higher temperatures. Quantum chemical calculations were done using DFT at the B3LYP/6-31G1 level to study the electronic properties of the molecules for correlating the inhibitive effect and molecular structure. 相似文献
102.
Wireless Personal Communications - The advancements of technology in the field of communication made WSN based IoT attractive and applicable to various areas. It is comprised IoT nodes that work on... 相似文献
103.
Microsystem Technologies - In the current paper, a new temperature sensor with improved temperature inaccuracy and with very low power consumption has been designed for avionic industry. The... 相似文献
104.
The objective of this research was to study the performance and emission characteristics of using waste plastic pyrolysis oil in diesel engine without any engine modification. The engine used in this study is a four-stroke single-cylinder naturally aspirated diesel engine (compression ignition). In the present work, the engine fuelled with blends of diesel fuel (DF) with plastic oil in the ratio of 90:10 (blend10%), 80:20 (blend20%), 70:30 (blend30%), and 50:50 (blend50%) are experimentally measured the efficiencies and emissions, analysed the performance, and compared results with that of DF. 相似文献
105.
Prasad Rama Sreenivas Kummara Rajdip Bandyopadhyaya Ajay S. Panwar Arup R. Bhattacharyya 《Polymer Engineering and Science》2020,60(11):2864-2875
This investigation was aimed to enhance the dispersibility of multi-walled carbon nanotubes (MWCNT) using sodium polystyrene sulfonate (Na-PSS) polyelectrolyte. Subsequently, electrically conducting, multi-layer thin films are prepared utilizing layer by layer assembly method with poly(vinyl alcohol) as a host matrix. The highest extent of MWCNT dispersion was observed in MWCNT:Na-PSS ratio of 1:9 (wt/wt), which was estimated from UV-Vis spectroscopic analysis. Zeta potential measurements of Na-PSS modified MWCNT dispersion showed large negative potentials ranging from −52 to −64 mV in the most stable pH range of 4 to 10, suggesting the colloidal stability is due to the long-range repulsive nature of electrostatic interactions from negatively charged sulfonate groups. Complementary molecular dynamics simulations showed that adsorption of Na-PSS imparts a large negative potential to the carbon nanotube surface, which increases with an increase in Na-PSS concentration. The multi-layer thin film of (1:9) MWCNT:Na-PSS exhibited a DC electrical conductivity of 2.96 × 102 S/m. 相似文献
106.
New pseudo-dynamic analysis of two-layered cohesive-friction soil slope and its numerical validation
Suman HAZARI Sima GHOSH Richi Prasad SHARMA 《Frontiers of Structural and Civil Engineering》2020,14(6):1492
Natural slopes consist of non-homogeneous soil profiles with distinct characteristics from slopes made of homogeneous soil. In this study, the limit equilibrium modified pseudo-dynamic method is used to analyze the stability of two-layered c-φ soil slopes in which the failure surface is assumed to be a logarithmic spiral. The zero-stress boundary condition at the ground surface under the seismic loading condition is satisfied. New formulations derived from an analytical method are proposed for the predicting the seismic response in two-layered soil. A detailed parametric study was performed in which various parameters (seismic accelerations, damping, cohesion, and angle of internal friction) were varied. The results of the present method were compared with those in the available literature. The present analytical analysis was also verified against the finite element analysis results. 相似文献
107.
Henrik Beelen Kartik Mundaragi Shivakumar Luc Raijmakers M.C.F. Donkers Henk Jan Bergveld 《国际能源研究杂志》2020,44(4):2889-2908
In order to meet the required power and energy demand of battery-powered applications, battery packs are constructed from a multitude of battery cells. For safety and control purposes, an accurate estimate of the temperature of each battery cell is of vital importance. Using electrochemical impedance spectroscopy (EIS), the battery temperature can be inferred from the impedance. However, performing EIS measurements simultaneously at the same frequency on each cell in a battery pack introduces crosstalk interference in surrounding cells, which may cause EIS measurements in battery packs to be inaccurate. Also, currents flowing through the pack interfere with impedance measurements on the cell level. In this paper, we propose, analyse, and validate a method for estimating the battery temperature in a battery pack in the presence of these disturbances. First, we extend an existing and effective estimation framework for impedance-based temperature estimation towards estimating the temperature of each cell in a pack in the presence of crosstalk and (dis)charge currents. Second, the proposed method is analysed and validated on a two-cell battery pack, which is the first step towards development of this method for a full-size battery pack. Monte Carlo simulations are used to find suitable measurement settings that yield small estimation errors and it is demonstrated experimentally that, over a range of temperatures, the method yields an accuracy of ±1°C in terms of bias, in the presence of both disturbances. 相似文献
108.
Chi-Ho Lee Arjun Sapkota Bhakta Prasad Gaire Ji Woong Choi 《International journal of molecular sciences》2020,21(22)
Lysophosphatidic acid receptor 1 (LPA1) contributes to brain injury following transient focal cerebral ischemia. However, the mechanism remains unclear. Here, we investigated whether nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome activation might be an underlying mechanism involved in the pathogenesis of brain injury associated with LPA1 following ischemic challenge with transient middle cerebral artery occlusion (tMCAO). Suppressing LPA1 activity by its antagonist attenuated NLRP3 upregulation in the penumbra and ischemic core regions, particularly in ionized calcium-binding adapter molecule 1 (Iba1)-expressing cells like macrophages of mouse after tMCAO challenge. It also suppressed NLRP3 inflammasome activation, such as caspase-1 activation, interleukin 1β (IL-1β) maturation, and apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) speck formation, in a post-ischemic brain. The role of LPA1 in NLRP3 inflammasome activation was confirmed in vitro using lipopolysaccharide-primed bone marrow-derived macrophages, followed by LPA exposure. Suppressing LPA1 activity by either pharmacological antagonism or genetic knockdown attenuated NLRP3 upregulation, caspase-1 activation, IL-1β maturation, and IL-1β secretion in these cells. Furthermore, nuclear factor-κB (NF-κB), extracellular signal-regulated kinase 1/2 (ERK1/2), and p38 were found to be LPA1-dependent effector pathways in these cells. Collectively, results of the current study first demonstrate that LPA1 could contribute to ischemic brain injury by activating NLRP3 inflammasome with underlying effector mechanisms. 相似文献
109.
Food Science and Biotechnology - A series of methyl salicylate (MeSA)/β-cyclodextrin (β-CD) inclusion complexes (ICs) were prepared at different MeSA concentrations by the... 相似文献
110.
Wireless Personal Communications - The ongoing technological developments have totally transformed the lives of human beings. With the emergence of the smart era and the smart city concept, a few... 相似文献