全文获取类型
收费全文 | 1423篇 |
免费 | 65篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 8篇 |
综合类 | 3篇 |
化学工业 | 374篇 |
金属工艺 | 46篇 |
机械仪表 | 37篇 |
建筑科学 | 38篇 |
能源动力 | 96篇 |
轻工业 | 74篇 |
水利工程 | 25篇 |
石油天然气 | 11篇 |
无线电 | 146篇 |
一般工业技术 | 386篇 |
冶金工业 | 67篇 |
原子能技术 | 11篇 |
自动化技术 | 176篇 |
出版年
2024年 | 6篇 |
2023年 | 23篇 |
2022年 | 43篇 |
2021年 | 71篇 |
2020年 | 55篇 |
2019年 | 49篇 |
2018年 | 64篇 |
2017年 | 62篇 |
2016年 | 53篇 |
2015年 | 45篇 |
2014年 | 50篇 |
2013年 | 100篇 |
2012年 | 78篇 |
2011年 | 93篇 |
2010年 | 76篇 |
2009年 | 57篇 |
2008年 | 79篇 |
2007年 | 57篇 |
2006年 | 49篇 |
2005年 | 36篇 |
2004年 | 29篇 |
2003年 | 18篇 |
2002年 | 26篇 |
2001年 | 15篇 |
2000年 | 14篇 |
1999年 | 12篇 |
1998年 | 25篇 |
1997年 | 14篇 |
1996年 | 26篇 |
1995年 | 16篇 |
1994年 | 11篇 |
1993年 | 18篇 |
1992年 | 12篇 |
1991年 | 17篇 |
1990年 | 14篇 |
1989年 | 15篇 |
1988年 | 8篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1978年 | 6篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1972年 | 2篇 |
1965年 | 1篇 |
排序方式: 共有1498条查询结果,搜索用时 15 毫秒
41.
This paper presents the steady state behaviour and maintenance planning of the desulphurization process in the fertilizer industry. The process consists of four subsystems, A, B, C and D in series with three states; good, reduced and failed. One standby unit is provided for each pump. Taking constant failure and repair rates for each subsystem, mathematical modelling is done using the Chapman-Kolmogorov birth-death process. An expression for steady state availability is given. Based on the data available from a medium sized ammonia production process, the behaviour of each working unit in the process has been analysed. The computed results are discussed with the concerned plant personnel which is helpful to the management for implementing any future plan regarding design modification of the system/processes. 相似文献
42.
This work is based on the observation that existing energy management techniques for mobile devices, such as Dynamic Voltage
Scaling (DVS), are non-cooperative in the sense that they reduce the energy consumption of a single device, disregarding potential
consequences for other constraints (e.g., end-to-end deadlines) and/or other devices (e.g., energy consumption on neighboring
devices). This paper argues that energy management in distributed wireless real-time systems has to be end-to-end in nature,
requiring a coordinated approach among communicating devices. A cooperative distributed energy management technique (Co-DVS)
is proposed that (1) adapts and maintains end-to-end latencies within specified timeliness requirements (deadlines) and (2)
enhances energy savings at the devices with the highest pay-off factors that represent the relative benefits or significance of conserving energy at a device. The proposed technique employs a feedback-based
approach to dynamically distribute end-to-end slack among the devices based on their pay-off factors. 相似文献
43.
Xiaoyu Che Christopher R. Brydges Yuanzhi Yu Adam Price Shreyas Joshi Ayan Roy Bohyun Lee Dinesh K. Barupal Aaron Cheng Dana March Palmer Susan Levine Daniel L. Peterson Suzanne D. Vernon Lucinda Bateman Mady Hornig Jose G. Montoya Anthony L. Komaroff Oliver Fiehn W. Ian Lipkin 《International journal of molecular sciences》2022,23(14)
Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a chronic and debilitating disease characterized by unexplained physical fatigue, cognitive and sensory dysfunction, sleeping disturbances, orthostatic intolerance, and gastrointestinal problems. People with ME/CFS often report a prodrome consistent with infections. Using regression, Bayesian and enrichment analyses, we conducted targeted and untargeted metabolomic analysis of plasma from 106 ME/CFS cases and 91 frequency-matched healthy controls. Subjects in the ME/CFS group had significantly decreased levels of plasmalogens and phospholipid ethers (p < 0.001), phosphatidylcholines (p < 0.001) and sphingomyelins (p < 0.001), and elevated levels of dicarboxylic acids (p = 0.013). Using machine learning algorithms, we were able to differentiate ME/CFS or subgroups of ME/CFS from controls with area under the receiver operating characteristic curve (AUC) values up to 0.873. Our findings provide the first metabolomic evidence of peroxisomal dysfunction, and are consistent with dysregulation of lipid remodeling and the tricarboxylic acid cycle. These findings, if validated in other cohorts, could provide new insights into the pathogenesis of ME/CFS and highlight the potential use of the plasma metabolome as a source of biomarkers for the disease. 相似文献
44.
R. K. Tyagi K. K. Srivastava R. S. Pandey 《Surface Engineering and Applied Electrochemistry》2012,48(1):64-68
The material removal within different machining process can be performed in distinct modalities. One of the modality is based
on the effect of impact phenomenon. In this paper theoretical model of non-traditional machining process based on impact phenomenon
is discussed. The material is removed from the surface due to the impact of ions. The velocity of ions is equal to the velocity
at which the electrostatic ion-cyclotron instability driven by parallel flow velocity shear generated by massive ions takes
place. The main ways for the material removal as consequence of the impact phenomenon are the microcracking, microcutting,
melting and vaporizing of small quantities from the work-piece surface layer. 相似文献
45.
Multimedia Tools and Applications - Robust tracking of moving objects is still an open problem in computer vision. The problem and its difficulty depend on many factors, which includes the... 相似文献
46.
Pravin Kumar Dinesh Kumar Sharma Mahendra Singh Ashawat 《European Journal of Lipid Science and Technology》2021,123(10):2100002
This work aims to develop and evaluate the efficacy of tea tree oil (TTO) ethosomal cream with improved deposition in skin layers for treatment of atopic dermatitis (AD). Ethosomes of TTO are developed using phosphatidylcholine (2% and 3% w/v) and ethanol (20%, 30%, and 40% w/v). Ethosomes are evaluated for percent entrapment efficiency (%EE), vesicle size, zeta potential, and in vitro drug diffusion. Ethosomal creams with optimized ethosomal dispersion are developed and evaluated for physicochemical parameters, thermal stability, ex vivo permeation, skin retention, and in vitro cytotoxicity using HaCat skin cell lines in comparison to conventional creams of TTO. In vivo investigations of optimized creams are performed using BALB/c mice model. The %EE, vesicle size, and zeta potential for optimized ethosomes are found to be 76.19 ± 3.26%, 333.6 nm, and –35.3 mV, respectively. Ethosomal creams showed higher deposition in the epidermis and dermis. The optimized creams are non-cytotoxic to HaCat cell lines. The creams significantly reduce the inflammatory response by decreasing the clinical score and infiltration of white blood cells, eosinophils, and IgE antibodies. Overall efficacy of ethosomal cream is higher than conventional cream. In conclusion, optimized ethosomal cream of TTO shows good efficacy for treatment of AD. Practical applications : The method used for the formulation of ethosomes is simple and can be easily scaled up on the industrial level. The loading of TTO within ethosomes can increase the efficiency by enhanced drug deposition in the epidermis and might also improve its stability against oxidative degradation. Topical ethosomal cream of TTO can improve patient compliance by avoidance of adverse effects linked with corticosteroids and could be a possible complementary or alternative therapy in management of AD. 相似文献
47.
Kurtulus Kullu Uğur Güdükbay Dinesh Manocha 《Autonomous Agents and Multi-Agent Systems》2017,31(6):1403-1423
Behavioral plausibility is one of the major aims of crowd simulation research. We present a novel approach that simulates communication between the agents and assess its influence on overall crowd behavior. Our formulation uses a communication model that tends to simulate human-like communication capability. The underlying formulation is based on a message structure that corresponds to a simplified version of Foundation for Intelligent Physical Agents Agent Communication Language Message Structure Specification. Our algorithm distinguishes between low- and high-level communication tasks so that ACMICS can be easily extended and employed in new simulation scenarios. We highlight the performance of our communication model on different crowd simulation scenarios. We also extend our approach to model evacuation behavior in unknown environments. Overall, our communication model has a small runtime overhead and can be used for interactive simulation with tens or hundreds of agents. 相似文献
48.
Anshu Tyagi Florian Döring Hans-Ulrich Krebs Astrid Pundt 《International Journal of Hydrogen Energy》2017,42(35):22575-22582
The influence of a thin polycarbonate de-adhesion layer on the hydrogen concentration is studied on 30 nm vanadium films deposited on glass substrates, using electrochemical hydrogenography in an optical microscopy and scanning tunneling microscopy. It is shown that the optical reflection provides information about the de-adhesion morphology (buckles) while the optical transmission signal gives information about concentration and film thickness changes. Artificially patterned samples allow simultaneous studying adhered and de-adhered film parts, for similar mean concentrations. The optical data clearly show a different hydrogen behavior of the two parts. Data interpretation suggests higher local hydrogen content in the adhered film parts than for the detached films parts. Strong changes in the optical transmission of the adhered film parts can be attributed to strong morphological changes at the film surface. These changes are mainly attributed to grain sliding processes in the vanadium film. 相似文献
49.
Singh Dalip Saini Ajay Dhayal Veena Agarwal Dinesh Chandra 《Protection of Metals and Physical Chemistry of Surfaces》2019,55(4):682-688
Protection of Metals and Physical Chemistry of Surfaces - Dense alumina coatings were fabricated over aluminum alloy via dip coating method using oxime-modified aluminum(III) isopropoxide as a... 相似文献
50.
Meena Nemiwal Tian C. Zhang Dinesh Kumar 《International Journal of Hydrogen Energy》2021,46(41):21401-21418
Recently, carbon-based materials (e.g., graphene, carbon nanotubes, carbon quantum dots) have been used as electrocatalysts to catalyze the reactions such as hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR). Among them, graphene has attracted attention as an electrocatalyst, and its electrocatalytic performances have been improved by doping with metals and non-metals, surface and defect engineering, and hybrid development. In this perspective, the present paper reviewed the recent advances (2018 onwards) on the progress of graphene-based electrocatalysts for HER and overall water splitting (OWS). It is emphasizing strategies for optimizing electrocatalytic properties followed by challenges and future outlook. This review will provide the essential ideas and strategies that can help design graphene-based electrocatalysts of high performance that can be implemented for sustainable energy application. 相似文献