全文获取类型
收费全文 | 522篇 |
免费 | 34篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 85篇 |
金属工艺 | 20篇 |
机械仪表 | 20篇 |
建筑科学 | 16篇 |
矿业工程 | 2篇 |
能源动力 | 21篇 |
轻工业 | 48篇 |
水利工程 | 23篇 |
无线电 | 75篇 |
一般工业技术 | 128篇 |
冶金工业 | 55篇 |
原子能技术 | 3篇 |
自动化技术 | 64篇 |
出版年
2023年 | 13篇 |
2022年 | 25篇 |
2021年 | 43篇 |
2020年 | 27篇 |
2019年 | 24篇 |
2018年 | 30篇 |
2017年 | 38篇 |
2016年 | 32篇 |
2015年 | 12篇 |
2014年 | 24篇 |
2013年 | 33篇 |
2012年 | 31篇 |
2011年 | 35篇 |
2010年 | 14篇 |
2009年 | 27篇 |
2008年 | 16篇 |
2007年 | 13篇 |
2006年 | 14篇 |
2005年 | 11篇 |
2004年 | 7篇 |
2003年 | 3篇 |
2002年 | 9篇 |
2001年 | 5篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 12篇 |
1997年 | 10篇 |
1996年 | 5篇 |
1995年 | 6篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 3篇 |
排序方式: 共有564条查询结果,搜索用时 0 毫秒
101.
102.
Based on previous results of bond strength, scanning electron microscopy(SEM)/energy dispersive spectroscopy (EDS) and x-ray
photoelectron spectroscopy (for thin film thickness in the range of 50 to 200 nm range), it is expected for a moderate film
thickness of titanium (over 50 nm) for the system of sputtered Ti-coated glass/polymer two factors play important roles in
getting strong bond between Ti/Polyimide interface: (i) mechanical interlocking property and (ii) chemical bond formation
such as Ti-C, Ti-O between Ti and imidex (PI) film. In this study, a systematic investigation has been conducted to understand
the effects of thin films on bond quality and on failure mechanism of the interface between 400 nm sputtered Ti-coated glass/imidex
(PI) system. This article basically studies if for this higher film thickness the failure pattern and bond strength are consistent
with the previous data. From previous studies (for thin film thickness of 50 to 200 nm) the conclusion extracted is thin film
with thickness of less than 50 nm exhibited low bond strength when compared to film thickness over 50 nm and from the results
obtained in this study it is concluded that the bond reliability and failure modes of sputtered Ti film on glass are consistent
even for a film thickness as high as 400 nm and three types of failure modes are found : (i) cohesive failure mode, (ii) Ti/glass
interface failure mode, and (iii) glass failure mode. The roughness value for this coating thickness is 17 nm. 相似文献
103.
Elemental analyses of kohl (stone) samples collected from three different parts of the world were performed using laser-induced breakdown spectroscopy (LIBS). The analyses indicated that lead (Pb), copper (Cu), silver (Ag), iron (Fe), calcium (Ca), aluminum (Al), silicon (Si), and sodium (Na) were present in all the kohl samples. In addition to these elements, the sample from Madina, Kingdom of Saudi Arabia (KSA), contained the elements tin (Sn), zirconium (Zr), and antimony (Sb). The sample from Mount Toor, Egypt, also contained Sn. Also, quantitative analysis for lead was carried out by the standard addition method using the LIBS technique. The result showed the presence of 14.12 ± 0.28% by weight of Pb in the sample from Madina, which compares well with the measurement done using atomic absorption spectroscopy (AAS) (13.31 ± 0.46%). The standard addition method used three calibration curves drawn for three emission lines of the LIBS spectra of Pb. The limits of detection (LoD) for these calibration curves varied from 0.27% to 1.16% by weight. The lead contents of the samples from Mount Toor and the local market of Bangladesh were also measured by the AAS technique, and the results were 14.61 ± 0.48% and 8.98 ± 0.35% by weight, respectively. The reason for determining only the lead content in kohl, which may be used as an eye cosmetic, is the adverse effect that lead has on health. 相似文献
104.
105.
106.
Dai Q Rajasekharan R Butt H Qiu X Amaragtunga G Wilkinson TD 《Small (Weinheim an der Bergstrasse, Germany)》2012,8(16):2501-2504
An ultrasmall tunable microlens with a diameter of 1.5 μm is fabricated using nematic liquid crystals (electrically tunable medium) and vertically aligned carbon nanofibers (CNFs, electrodes). Individual CNFs are grown at the center of circular dielectric regions. This allows the CNFs to produce a more Gaussian electric field profile and hence more uniformity in lens array switching. 相似文献
107.
Golam Rasul Abid Hussain Bidhubhusan Mahapatra Narendra Dangol 《Journal of the science of food and agriculture》2018,98(2):429-438
The status of food and nutrition security and its underlying factors in the Hindu‐Kush Himalayan (HKH) region is investigated. In this region, one third to a half of children (<5 years of age) suffer from stunting, with the incidence of wasting and under‐weight also being very high. The prevalence of stunting, wasting and under‐weight in children is particularly high in some mountain areas such as Meghalaya state in India, the western mountains and far‐western hills of Nepal, Balochistan province in Pakistan, eastern Afghanistan, and Chin state in Myanmar. Food habits in the HKH region are changing. This has led to a deterioration in traditional mountain food systems with a decline in agrobiodiversity. Factors such as high poverty and low dietary energy intakes, a lack of hygienic environments, inadequate nutritional knowledge, and climate change and environmental degradation are also influencing food and nutrition security in the HKH region. To achieve sustainable food and nutrition security in the mountains, this study suggests a multi‐sectoral integrated approach with consideration of nutritional aspects in all development processes dealing with economic, social, agricultural and public health issues. © 2017 Society of Chemical Industry 相似文献
108.
Hassan Iqbal Solomon Tesfamariam Husnain Haider Rehan Sadiq 《Structure and Infrastructure Engineering》2017,13(6):794-815
Oil and gas (O&G) pipelines are expensive assets that cross through both the ecologically sensitive and densely populated urban areas. The pipeline failure may have potentially significant consequences for both the natural and human environments. In order to maintain the integrity of O&G pipelines, inspection and maintenance processes should be governed by efficient policies. The objective of this paper is to conduct a state-of-the-art review of maintenance policies of O&G pipelines to investigate their advantages, limitations, and associated implementation issues. Maintenance policies can be categorised into corrective, preventive, predictive and proactive. Corrective maintenance policies (1940s) were based on the ‘repair when broke’ philosophy. Economic considerations shifted practice towards preventive maintenance (1970s to 1990s); later with improved inspection techniques and environmental regulations, predictive and proactive or risk-based maintenance (RBM) policies were developed. This review explicates different methodologies for RBM and related issues, e.g. uncertainties and variability, conservative assumptions, etc. Uncertainties associated with investigation and prediction of defects have been more frequently reported in the literature so far. Moreover, existing studies primarily focused on reducing the likelihood and cost of failure, whereas consideration of environmental factors in overall risk has been a relatively less addressed issue. 相似文献
109.
Peter Haider Bertram Kimmerle Frank Krumeich Wolfgang Kleist Jan-Dierk Grunwaldt Alfons Baiker 《Catalysis Letters》2008,125(3-4):169-176
The effect of the size of gold particles deposited on CeO2 and TiO2 supports on their catalytic behavior in the aerobic oxidation of benzyl alcohol in different solvents (mesitylene, toluene, and supercritical carbon dioxide) has been investigated. The size of supported gold particles deposited via a colloidal route was in the range 1.3–11.3 nm, as determined by means of EXAFS and HAADF-STEM measurements. The catalytic performance of the supported gold catalysts in the different solvents revealed a significant effect of the gold particle size. Optimal activity was observed for catalysts with medium particle size (ca. 6.9 nm) whereas smaller and bigger particles showed inferior activity. Identical trends for the activity–particle size relationship were found using Au/CeO2 and Au/TiO2 for the reaction at atmospheric pressure in conventional solvents (mesitylene, toluene) as well as under supercritical conditions (scCO2). Selectivity to benzaldehyde was only weakly affected by the gold particle size and mainly depended on reaction conditions. In supercritical CO2 (scCO2) selectivity was higher than in the conventional solvents under atmospheric pressure. All catalysts tested with particle sizes ranging from 1.3 to 11.3 nm showed excellent selectivity of 99% or higher under supercritical conditions. 相似文献
110.
Julfikar Haider Mahfujur Rahman M. S. J. Hashmi Mohammed Sarwar 《Journal of Materials Science》2008,43(10):3368-3376
Significant progress has been made in the past decade in plasma nitriding with a majority of the research work focusing on improving hardness and wear resistance of the nitrided surface through the reduction of nitriding temperature, pressure or time. Hard-solid lubricating coatings have also been extensively studied for lowering the wear rate and coefficient of friction of traditional hard coatings such as TiN by the combined effect of hardness and solid lubrication. In this study, the wear characteristics of low-temperature plasma-nitrided steel substrate performed using a Saddle-field fast atom beam source and TiN + MoS x hard-solid lubricant coating deposited by a closed-field magnetron-sputtering technique have been investigated. The thin hard layer in plasma-nitrided substrates exhibited much higher hardness and lower wear compared to the untreated substrate in pin-on-disc wear testing. In addition, the study of the wear track morphology of the nitrided samples evidenced significant reduction of deeper ploughing and plastic deformation due to higher hardness and load supporting of the nitrided layer. On the other hand, due to the incorporation of MoS2 in TiN coating, the wear resistance and coefficient of friction were greatly improved in TiN + MoS x coating compared to pure TiN coating. In contrast to TiN coating, a relatively smoother wear track with less abrasive wear also supported the beneficial effects of adding MoS2 in TiN coating. 相似文献