全文获取类型
收费全文 | 2378篇 |
免费 | 28篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 28篇 |
综合类 | 3篇 |
化学工业 | 225篇 |
金属工艺 | 23篇 |
机械仪表 | 28篇 |
建筑科学 | 61篇 |
矿业工程 | 2篇 |
能源动力 | 26篇 |
轻工业 | 186篇 |
水利工程 | 14篇 |
石油天然气 | 24篇 |
无线电 | 98篇 |
一般工业技术 | 250篇 |
冶金工业 | 1247篇 |
原子能技术 | 27篇 |
自动化技术 | 165篇 |
出版年
2022年 | 9篇 |
2021年 | 10篇 |
2020年 | 8篇 |
2019年 | 14篇 |
2018年 | 18篇 |
2017年 | 15篇 |
2016年 | 18篇 |
2015年 | 20篇 |
2014年 | 16篇 |
2013年 | 58篇 |
2012年 | 44篇 |
2011年 | 71篇 |
2010年 | 36篇 |
2009年 | 50篇 |
2008年 | 68篇 |
2007年 | 54篇 |
2006年 | 47篇 |
2005年 | 31篇 |
2004年 | 33篇 |
2003年 | 53篇 |
2002年 | 26篇 |
2001年 | 35篇 |
2000年 | 30篇 |
1999年 | 60篇 |
1998年 | 424篇 |
1997年 | 220篇 |
1996年 | 132篇 |
1995年 | 99篇 |
1994年 | 83篇 |
1993年 | 89篇 |
1992年 | 21篇 |
1991年 | 19篇 |
1990年 | 36篇 |
1989年 | 23篇 |
1988年 | 31篇 |
1987年 | 19篇 |
1986年 | 23篇 |
1985年 | 21篇 |
1984年 | 22篇 |
1983年 | 22篇 |
1982年 | 15篇 |
1981年 | 18篇 |
1980年 | 19篇 |
1979年 | 9篇 |
1978年 | 18篇 |
1977年 | 35篇 |
1976年 | 70篇 |
1975年 | 11篇 |
1973年 | 10篇 |
1972年 | 9篇 |
排序方式: 共有2407条查询结果,搜索用时 703 毫秒
51.
52.
Xuesong Liu Burcu Akinci Mario Bergés James H. Garrett 《Advanced Engineering Informatics》2013,27(4):496-505
Heating, Ventilation and Air-Conditioning (HVAC) systems account for more than 15% of the total energy consumption in the US. In order to improve the energy efficiency of HVAC systems, researchers have developed hundreds of algorithms to automatically analyze their performance. However, the complex information, such as configurations of HVAC systems, layouts and materials of building elements and dynamic data from the control systems, required by these algorithms inhibits the process of deploying them in real-world facilities. To address this challenge, we envision a framework that automatically integrates the required information items and provides them to the performance analysis algorithms for HVAC systems. This paper presents an approach to identify and document the information requirements from the publications that describe these algorithms. We extend the Information Delivery Manual (IDM) approach so that the identified information requirements can be mapped to multiple information sources that use various formats and schemas. This paper presents the extensions to the IDM approach and the results of using it to identify information requirements for performance analysis algorithms of HVAC systems. 相似文献
53.
WANG Jiang FAUTRELLE Yves REN Zhong-ming LI Xi NGUYEN-THI Henri MANGELINCK-NOEL Nathalie SALLOUM ABOU JAOUDE Georges ZHONG Yun-bo KALDRE Imants BOJAREVICS Andris BULIGINS Leonid 《钢铁研究学报(英文版)》2012,(Z1):381-385
Sn-3wt%Pb alloy was directionally solidified without and with a 0.08T transverse magnetic field(TMF),and real-time recorded by in-situ synchrotron X-ray imaging.Results indicate that TMF shortened the distance from the location of nucleation to the advancing interface,and accelerated the growth rate of the equiaxed crystal,which caused the columnar-to-equiaxed transition(CET)finally.The thermoelectromagnetic convection(TEMC)in front of the interface and around the crystal’s dendritic branch should respond to changes of the distance and the growth rate. 相似文献
54.
The objectives of this study were to educate consumers about value-added beef cuts and evaluate their palatability responses of a value cut and three traditional cuts. Three hundred and twenty-two individuals participated in the beef value cut education seminar series presented by trained beef industry educators. Seminar participants evaluated tenderness, juiciness, flavor, and overall like of four samples, bottom round, top sirloin, ribeye, and a value cut (Delmonico or Denver), on a 9-point scale. The ribeye and the value cut were found to be similar in all four attributes and differed from the top sirloin and bottom round. Correlations and regression analysis found that flavor was the largest influencing factor for overall like for the ribeye, value cut, and top sirloin. The value cut is comparable to the ribeye and can be a less expensive replacement. 相似文献
55.
56.
Hrvoje Mikulčić Eberhard von Berg Milan Vujanović Peter Priesching Luka Perković Reinhard Tatschl Neven Duić 《Chemical engineering science》2012,69(1):607-615
Calcination is a thermo-chemical process, widely used in the cement industry, where limestone is converted by thermal decomposition into lime CaO and carbon dioxide CO2. The focus of this paper is on the implementation and validation of the endothermic calcination reaction mechanism of limestone in a commercial finite volume based CFD code. This code is used to simulate the turbulent flow field, the temperature field, concentrations of the reactants and products, as well as the interaction of particles with the gas phase, by solving the mathematical equations, which govern these processes. For calcination, the effects of temperature, decomposition pressure, diffusion and pore efficiency were taken into account. A simple three-dimensional geometry of a pipe reactor was used for numerical simulations. To verify the accuracy of the modelling approach, the numerical predictions were compared with experimental data, yielding satisfying results and proper trends of physical parameters influencing the process. 相似文献
57.
Trace Elements in the Si Furnace-Part II: Analysis of Condensate in Carbothermal Reduction of Quartz
Elena Dal Martello Gabriella Tranell Oleg Ostrovski Guangqing Zhang Ola Raaness Rune Berg Larsen Kai Tang Pramod Koshy 《Metallurgical and Materials Transactions B》2013,44(2):244-251
Silicon feedstock for production of solar-grade silicon should be as pure as possible to decrease the cost of manufacturing of solar cells. Impurities in quartz, carbonaceous materials, electrodes, and refractories are mostly present in the form of oxides. These oxides can be reduced to volatile gaseous compounds in presence of SiO(g) and CO(g) atmosphere and potentially leave the furnace or stay in the condensed reaction products, metal, and slag. This work investigates the conditions under which volatile impurities report to the gas phase in laboratory experiments with lumpy and pelletized mixtures of SiO2, SiC, and Si at 1923 K and 2123 K (1650 °C and 1850 °C), respectively, were carried out. The volatile compounds were generated by the reduction of quartz and collected in the form of condensate. The effects of the reaction temperature, quartz type, charge composition, pellets, and lumps on the composition of the condensate were studied. The trace elements in the charge input, reacting charge, and condensate were analyzed using inductively coupled plasma (ICP)-mass spectroscopy (MS) and X-ray diffraction (XRD). CO(g) and SiO(g), which are the major components in reduction reactions, formed four types of condensate: white, brown, green, and orange. The condensate constituents were amorphous SiO2, 3C:SiC, Si, and α-quartz. Each impurity present in the quartz charge entered the gas phase during quartz reduction and was detected in the condensate. Al and Fe show limited volatility. The volatility of Mn, P, and B depends on the charge mix: a higher PCO enhances the concentration of these elements in the gas phase. Fluid inclusions, common in hydrothermal quartz, enhance the distribution of the contaminants to the gas phase. Industrial campaigns on Si and Fe-Si production confirm the experimental results. 相似文献
58.
Currently available treatments for the degenerated intervertebral disc present disadvantages, such as surgical invasiveness and inadequate load distribution results. Load-bearing, injectable materials may be interesting for future therapies, but have not been studied in depth. In this study, the existing literature was screened for studies on injectable materials for the intervertebral disc and a rationale for load-bearing, injectable materials was formulated. Requirements for such a material were discussed, partly based on the experience of materials used for similar applications. Important properties were discussed and found to include biocompatibility, bioactivity, porosity, handling, injectability, working time, setting time, radiopacity, containment and mechanical properties, where several of these properties are linked to one another. In conclusion, there is a need for consensus on the properties of new materials developed for use in minimally invasive procedures in the spine. A substantial amount of attention may need to be given to non-toxic setting reactions. 相似文献
59.
Rachel E. Sheldon Chipo Mashayamombe Shao-Qing Shi Robert E. Garfield Anatoly Shmygol Andrew M. Blanks Hugo A. van den Berg 《Journal of the Royal Society Interface》2014,11(101)
The smooth muscle cells of the uterus contract in unison during delivery. These cells achieve coordinated activity via electrical connections called gap junctions which consist of aggregated connexin proteins such as connexin43 and connexin45. The density of gap junctions governs the excitability of the myometrium (among other factors). An increase in gap junction density occurs immediately prior to parturition. We extend a mathematical model of the myometrium by incorporating the voltage-dependence of gap junctions that has been demonstrated in the experimental literature. Two functional subtypes exist, corresponding to systems with predominantly connexin43 and predominantly connexin45, respectively. Our simulation results indicate that the gap junction protein connexin45 acts as a negative modulator of uterine excitability, and hence, activity. A network with a higher proportion of connexin45 relative to connexin43 is unable to excite every cell. Connexin45 has much more rapid gating kinetics than connexin43 which we show limits the maximum duration of a local burst of activity. We propose that this effect regulates the degree of synchronous excitation attained during a contraction. Our results support the hypothesis that as labour approaches, connexin45 is downregulated to allow action potentials to spread more readily through the myometrium. 相似文献
60.
Sudden cardiac death (SCD) is a major cause of mortality in Western countries. Furthermore, SCD is often the first manifestation of coronary artery disease, making it difficult to prevent. Heart rate variability (HRV), which can be determined by extended recording of the heart rate by 24-h Holter monitoring, has been shown to be one of the best predictors of the risk of SCD. There is increasing evidence from animal experiments and clinical trials in humans that n?3 fatty acids reduce the risk of SCD. We have studied the effect of n?3 fatty acids on HRV and present data clearly showing that n?3 fatty acids increase HRV. This adds further to the hypothesis that an increased intake of n?3 fatty acids may reduce the risk of SCD. 相似文献