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61.
Ensemble of surrogates 总被引:5,自引:3,他引:2
Tushar Goel Raphael T. Haftka Wei Shyy Nestor V. Queipo 《Structural and Multidisciplinary Optimization》2007,33(3):199-216
The custom in surrogate-based modeling of complex engineering problems is to fit one or more surrogate models and select the
one surrogate model that performs best. In this paper, we extend the utility of an ensemble of surrogates to (1) identify
regions of possible high errors at locations where predictions of surrogates widely differ, and (2) provide a more robust
approximation approach. We explore the possibility of using the best surrogate or a weighted average surrogate model instead
of individual surrogate models. The weights associated with each surrogate model are determined based on the errors in surrogates.
We demonstrate the advantages of an ensemble of surrogates using analytical problems and one engineering problem. We show
that for a single problem the choice of test surrogate can depend on the design of experiments. 相似文献
62.
钍在轻水堆中利用的研究 总被引:1,自引:0,他引:1
对钍-232在轻水堆中利用进行了研究。考虑到现行轻水堆改型的方便,以秦山核电厂反应堆参数为基础,只改变堆芯燃料组分,在可裂变材料总量不变的条件下,对不同钍-232装量进行了多方案研究。结果表明,由于钍-232吸收中子后的主要转换产物是铀-233,它在热堆中的η值比铀-235和钚-239的高,因此在同样初始过剩反应性情况下,随着钍-232装量的增大,燃耗的加深,堆内易裂变材料总生成量也随之增大,转换比提高,从而使堆芯寿期延长,节省了核燃料。可见钍是一种有前途的能源资源。此外必须指出,在所研究的参数条件下以钍-铀重量比0.25为佳。 相似文献
63.
碳酸盐岩地层自然伽马能谱测井曲线质量评价 总被引:1,自引:1,他引:0
:碳酸盐岩地层中自然放射性元素含量低,自然伽马值一般低于10API,由此进行剥谱分析而得到的铀(U)、钍(Th)、钾(K)曲线也都很低,有时甚至出现回零现象,因此控制自然伽马能谱测井曲线质量,避免解释错误是应用自然伽马能谱曲线进行测井解释的重要环节。为此,通过自然伽马能谱测井所测量的U,Th, K含量,研究提取铀相对比值和钍/铀比值,并对其进行交会、重叠等分析,可快速直观地对自然伽马能谱测井资料进行质量检查。目前这种方法在塔河油田中、下奥陶统碳酸盐岩地层曲线质量控制中得到了很好的应用。 相似文献
64.
一种评价能谱测井质量的直观比值法 总被引:1,自引:1,他引:0
李桂荣 《勘探地球物理进展》2004,27(4):266-268
能谱测井反映地层沉积岩的自然放射性,通过对自然伽马能谱测井资料的地质分析,提取自然放射性铀相对比值和钍/铀比值,用于快速直观地对自然伽马能谱测井资料进行质量监控。目前这种方法在塔河油田奥陶系碳酸岩盐地层的能谱测井资料质量评价中取得了明显的效果。 相似文献
65.
Design of Computer Experiments for Metamodel Generation 总被引:2,自引:0,他引:2
We review the use of statistical design and analysis of computer experiments (DACE) for the generation of parsimonious, surrogate models, also known as metamodels. Such metamodels are used to replace cpu- or memory-intensive, discretized approximations that often arise in MEMS and MOEMS. Emphasis is placed on optimal designs. 相似文献
66.
67.
采用硝酸-过氧化氢溶解UF4,离子交换法分离去除干扰元素,分光光度法测定样品中的微量钍。在10mL试样中,钍含量在0—1.0μg范围内符合比尔定律,相对标准偏差小于4.5%,样品重加回收率为96.7%—103%。 相似文献
68.
J. K. Fink 《International Journal of Thermophysics》1982,3(2):165-200
The available enthalpy data on UO2, ThO2, PuO2, (Th, U)O2, and (Pu, U)O2 have been analyzed and equations have been derived to fit the data. Phase transitions were found in UO2, ThO2, (Th, U)O2, and (Pu, U)O2. The high temperature PuO2 data were too scattered to determine whether a phase transition exists. Above the phase transition temperature, the enthalpy data were fit with a linear equation. Enthalpy data for PuO2 and ThO2 below the phase transition temperature were fit with two-term equations whose contributions are due to phonons and thermal expansion. For UO2 below its phase transition, a term for an electronic contribution was added to this basic equation. Below the phase transitions for (Th, U)O2, enthalpy data were fit by a mole average of the equations used to fit the ThO2 and UO2 data below their phase transitions; however, the mole average equation was not valid for 90 and 92% ThO2 in the mixed oxide. Since it was found that mole averages of the PuO2 and UO2 data do not fit the (Pu, U)O2 data, these data were fit with an equation of the same form as that that used for UO2. 相似文献
69.
To acquire a high amount of information of the behaviour of the Homogeneous Charge Compression Ignition (HCCI) auto-ignition process, a reduced surrogate mechanism has been composed out of reduced n-heptane, iso-octane and toluene mechanisms, containing 62 reactions and 49 species. This mechanism has been validated numerically in a 0D HCCI engine code against more detailed mechanisms (inlet temperature varying from 290 to 500 K, the equivalence ratio from 0.2 to 0.7 and the compression ratio from 8 to 18) and experimentally against experimental shock tube and rapid compression machine data from the literature at pressures between 9 and 55 bar and temperatures between 700 and 1400 K for several fuels: the pure compounds n-heptane, iso-octane and toluene as well as binary and ternary mixtures of these compounds. For this validation, stoichiometric mixtures and mixtures with an equivalence ratio of 0.5 are used. The experimental validation is extended by comparing the surrogate mechanism to experimental data from an HCCI engine. A global reaction pathway is proposed for the auto-ignition of a surrogate gasoline, using the surrogate mechanism, in order to show the interactions that the three compounds can have with one another during the auto-ignition of a ternary mixture. 相似文献
70.