全文获取类型
收费全文 | 2276篇 |
免费 | 97篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 33篇 |
综合类 | 1篇 |
化学工业 | 483篇 |
金属工艺 | 69篇 |
机械仪表 | 54篇 |
建筑科学 | 144篇 |
矿业工程 | 8篇 |
能源动力 | 108篇 |
轻工业 | 231篇 |
水利工程 | 7篇 |
石油天然气 | 6篇 |
无线电 | 145篇 |
一般工业技术 | 514篇 |
冶金工业 | 152篇 |
原子能技术 | 25篇 |
自动化技术 | 395篇 |
出版年
2023年 | 8篇 |
2022年 | 30篇 |
2021年 | 42篇 |
2020年 | 28篇 |
2019年 | 47篇 |
2018年 | 43篇 |
2017年 | 53篇 |
2016年 | 57篇 |
2015年 | 54篇 |
2014年 | 65篇 |
2013年 | 140篇 |
2012年 | 101篇 |
2011年 | 179篇 |
2010年 | 115篇 |
2009年 | 161篇 |
2008年 | 132篇 |
2007年 | 139篇 |
2006年 | 104篇 |
2005年 | 107篇 |
2004年 | 91篇 |
2003年 | 57篇 |
2002年 | 73篇 |
2001年 | 43篇 |
2000年 | 30篇 |
1999年 | 36篇 |
1998年 | 61篇 |
1997年 | 40篇 |
1996年 | 29篇 |
1995年 | 22篇 |
1994年 | 20篇 |
1993年 | 22篇 |
1992年 | 12篇 |
1991年 | 19篇 |
1990年 | 17篇 |
1989年 | 15篇 |
1988年 | 18篇 |
1987年 | 14篇 |
1986年 | 16篇 |
1985年 | 15篇 |
1984年 | 11篇 |
1983年 | 12篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1980年 | 10篇 |
1979年 | 10篇 |
1978年 | 9篇 |
1977年 | 8篇 |
1976年 | 8篇 |
1974年 | 8篇 |
1966年 | 4篇 |
排序方式: 共有2375条查询结果,搜索用时 15 毫秒
91.
92.
In this article, an extended version of the unified theory of acceptance and use of technology (UTAUT) is applied to explore the significance of various antecedents of acceptance of eight versions of a radio frequency identification (RFID) enabled service. The results show significant influences from performance expectancy, effort expectancy and technology anxiety on attitude to use RFID-enabled services, while facilitating conditions and attitude to use both have significant influences on intention to use the services. Looking into potential moderating influences, gender moderates most of the relationships in the model while age and experience with identification technology do not seem to be relevant moderators. Exploring the potential moderating influence of context experience, experience of the service context is found to moderate some of the relationships in the model. Managerial implications point to the importance of developing useful and user-friendly services and of communicating the user friendliness to potential customers to avoid the potential negative influence of technology anxiety. Service development and market communication should be sensitive to gender and context experience. 相似文献
93.
94.
Livia Pagano Angelo Toto Francesca Malagrin Lorenzo Visconti Per Jemth Stefano Gianni 《International journal of molecular sciences》2021,22(2)
Quantitative measurement of intramolecular and intermolecular interactions in protein structure is an elusive task, not easy to address experimentally. The phenomenon denoted ‘energetic coupling’ describes short- and long-range interactions between two residues in a protein system. A powerful method to identify and quantitatively characterize long-range interactions and allosteric networks in proteins or protein–ligand complexes is called double-mutant cycles analysis. In this review we describe the thermodynamic principles and basic equations that underlie the double mutant cycle methodology, its fields of application and latest employments, and caveats and pitfalls that the experimentalists must consider. In particular, we show how double mutant cycles can be a powerful tool to investigate allosteric mechanisms in protein binding reactions as well as elusive states in protein folding pathways. 相似文献
95.
Scientometrics - Journal rankings often show significant changes compared to previous rankings. This gives rise to the question of how well estimated the rank of a journal is. In this contribution,... 相似文献
96.
97.
98.
Tero Luukkonen Emma-Tuulia Tolonen Hanna Runtti Kimmo Kemppainen Paavo Perämäki Jaakko Rämö Ulla Lassi 《Journal of Materials Science》2017,52(16):9363-9376
Geopolymers are functional materials that can be used in various environmental applications such as adsorbents in pollutant removal from wastewaters. Metakaolin geopolymer (MK-GP) has been proven to be especially suitable for ammonium (NH4 +) removal. In this research, the optimal reagent and raw material ratios in the preparation of MK-GP in terms of NH4 + adsorption capacity were investigated. The response surface methodology based on the face-centered central composite design was used to optimize the levels of three factors: the amounts of hydroxide, silicate, and metakaolin. In addition, the effect of Na or K as the charge-balancing cation was studied. Empirical models were fitted to the experimental data using multiple linear regression. The significance of the models was confirmed by means of analysis of variance. Optimal NH4 + removal efficiency was achieved when the amounts of hydroxide and silicate were maximized, the amount of metakaolin was minimized, and Na-based reagents were used. These trends are most likely a result of optimized conversion of metakaolin into MK-GP. 相似文献
99.
The naturally occurring mineral ilmenite, FeTiO3, has been examined as oxygen carrier for chemical-looping combustion. NiO-based particles have been used as an additive, in order to examine if it is possible to utilize the catalytic properties of metallic Ni to facilitate decomposition of hydrocarbons into more reactive combustion intermediates such as CO and H2. Firstly, ilmenite was examined by oxidation and reduction experiments in a batch fluidized-bed reactor. These experiments indicated moderate reactivity between ilmenite and CH4, which was used as reducing gas. However, adding 5 wt.% of NiO-based particles to the ilmenite improved the conversion of CH4 greatly, resulting in an increase in combustion efficiency with a factor of 3. Secondly, 83 h of chemical-looping combustion experiments were conducted in a small circulating fluidized-bed reactor, using ilmenite as oxygen carrier and natural gas as fuel. A wide range of process parameters and different levels of NiO addition were examined. Occasionally, there were problems with the circulation of solids between the air reactor and fuel reactor, but most of the time the experiments worked well. The products were mostly CO2, H2O and unconverted CH4. Adding small amounts of NiO-based particles to the reactor increased the conversion of the fuel considerably. For the base case conducted at 900°, the combustion efficiency was 76% for pure ilmenite and 90% for the corresponding experiments with 1 wt.% NiO-based particles added to the reactor. The properties of ilmenite were found to change considerably during operation. Used particles had lower density, were more reactive and more porous than fresh particles. These changes appear to have been physical, and no unexpected chemical phases could be identified. 相似文献
100.
Per Kreuger Rebecca Steinert Olof Görnerup Daniel Gillblad 《International Journal of Network Management》2018,28(2)
Managing and balancing load in distributed systems remains a challenging problem in resource management, especially in networked systems where scalability concerns favour distributed and dynamic approaches. Distributed methods can also integrate well with centralised control paradigms if they provide high‐level usage statistics and control interfaces for supporting and deploying centralised policy decisions. We present a general method to compute target values for an arbitrary metric on the local system state and show that autonomous rebalancing actions based on the target values can be used to reliably and robustly improve the balance for metrics based on probabilistic risk estimates. To balance the trade‐off between balancing efficiency and cost, we introduce 2 methods of deriving rebalancing actuations from the computed targets that depend on parameters that directly affects the trade‐off. This enables policy level control of the distributed mechanism based on collected metric statistics from network elements. Evaluation results based on cellular radio access network simulations indicate that load balancing based on probabilistic overload risk metrics provides more robust balancing solutions with fewer handovers compared to a baseline setting based on average load. 相似文献