全文获取类型
收费全文 | 162篇 |
免费 | 15篇 |
专业分类
化学工业 | 19篇 |
金属工艺 | 3篇 |
机械仪表 | 5篇 |
建筑科学 | 7篇 |
能源动力 | 6篇 |
轻工业 | 22篇 |
水利工程 | 17篇 |
无线电 | 10篇 |
一般工业技术 | 40篇 |
冶金工业 | 3篇 |
自动化技术 | 45篇 |
出版年
2024年 | 1篇 |
2022年 | 4篇 |
2021年 | 7篇 |
2020年 | 10篇 |
2019年 | 14篇 |
2018年 | 21篇 |
2017年 | 18篇 |
2016年 | 5篇 |
2015年 | 8篇 |
2014年 | 13篇 |
2013年 | 14篇 |
2012年 | 16篇 |
2011年 | 21篇 |
2010年 | 7篇 |
2009年 | 3篇 |
2008年 | 2篇 |
2006年 | 2篇 |
2005年 | 1篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1996年 | 1篇 |
1989年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有177条查询结果,搜索用时 15 毫秒
171.
172.
In this study, the effect of cutting parameters and machining forces on surface roughness and material removal rate of AL6061
in CNC face milling operation is investigated. Based on the experimental data, two different modeling techniques, namely regression
analysis and multilayer perceptron, MLP, neural network, have been used to estimate the state variables (i.e. surface roughness,
R
a
, and material removal rate, MRR). Simulation results presented using machining data demonstrate that the MLP neural network
possesses more powerful capacity than the regression analysis and performs the estimation of the R
a
and MRR, simultaneously. 相似文献
173.
Heritability,reliability of genetic evaluations and response to selection in proportional hazard models 总被引:1,自引:0,他引:1
The purposes of this study were 1) to investigate the heritability, reliability, and selection response for survival traits following a Weibull frailty proportional hazard model; and 2) to examine the relationship between genetic parameters from a Weibull model, a discrete proportional hazard model, and a binary data analysis using a linear model. Both analytical methods and Monte Carlo simulations were used to achieve these aims. Data were simulated using the Weibull frailty model with two different shapes of the Weibull distribution. Breeding values of 100 unrelated sires with 50 to 100 progeny (with different levels of censoring) were generated from a normal distribution and two different sire variances. For analysis of longevity data on the discrete scale, simulated data were transformed to a discrete scale using arbitrary ends of discrete intervals of 400, 800, or 1200 d. For binary data analysis, an individual's longevity was either 0 (when longevity was less than the end of interval) or 1 (when longevity was equal or greater than the end of interval). Three different statistical models were investigated in this study: a Weibull model, a discrete-time model (a proportional hazard model assuming that the survival data are measured on a discrete scale with few classes), and a linear model based upon binary data. An alternative derivation using basic expressions of reliabilities in sire models suggests a simple equation for the heritability on the original scale (effective heritability) that is not dependent on the Weibull parameters. The predictions of reliabilities using the proposed formulae in this study are in very good agreement with reliabilities observed from simulations. In general, the estimates of reliability from either the discrete model or the binary data analysis were close to estimates from the Weibull model for a given number of uncensored records in this simplified case of a balanced design. Although selection response from the binary data analysis depends on the end of interval point, there is a relatively good agreement between selection responses in the Weibull model and the binary data analysis. In general, when the underlying survival data is from a Weibull distribution, it appears that the method of analyzing data does not greatly affect the results in terms of sire ranking or response to selection, at least for the simplified context considered in this study. 相似文献
174.
OBJECTIVE: To study cervical exfoliated cells with Fourier transform infrared spectroscopy (FTIR). STUDY DESIGN: Consecutive samples from 133 women attending the Dysplasia Clinic, Ottawa Civic Hospital, were collected in balanced electrolyte solution. After centrifugation, two smears were prepared for routine screening. The remainder of the pellet was frozen for FTIR spectroscopic study. RESULTS: In 120 samples, adequate material was available for spectroscopic study. All smears from 17 women with normal spectra were within normal limits (WNL). One hundred three spectra were abnormal. The corresponding smears were interpreted as: 41 low grade squamous intraepithelial lesions, 20 high grade squamous intraepithelial lesions, 6 atypical squamous cells of undetermined significance, 17 cases with benign cellular changes, and 19 WNL. Ten of 17 cases with benign cellular changes had characteristic spectra consistent with inflammatory changes. CONCLUSION: FTIR spectroscopy is a highly sensitive technique for detecting cervical abnormalities and a potential tool for prescreening preinvasive lesions of the cervix. 相似文献
175.
Soheila Khoshnevis Yazdi Bahram Shakouri 《Energy Sources, Part B: Economics, Planning, and Policy》2018,13(2):121-127
Europe has experienced fast-paced urbanization development over the past three decades. This paper empirically investigates the long-run equilibrium relationships and causal relationships among urbanization, renewable energy consumption, and CO2 emissions, and this is important for EU countries’ future sustainable development. DOLS and FMOLS approaches are used for the period 1992–2014 .
Granger causality results show that there is a unidirectional relationship from CO2 emissions to urbanization, and there is no causality between renewable energy consumption and CO2 emissions. The results have important implications for EU policymakers on the path toward a sustainable society. Urbanization can have negative impacts on the natural environment with the net effect being hard in EU countries. 相似文献
176.
Soheila khoshnevis Yazdi Bahram Shakouri 《Energy Sources, Part B: Economics, Planning, and Policy》2018,13(1):53-59
This paper provides an empirical analysis of CO2 emissions and economic growth, renewable energy consumption, and energy consumption over the period 1975–2014 in Germany. This paper uses the autoregressive distributed lag (ARDL) approach of cointegration test and vector error-correction models. The unit root and cointegration tests show that the long-run relationship between CO2 emissions and its determinants. The empirical results show that the findings do not support the environmental Kuznets curve between real GDP and CO2 emissions. To estimate the shocks of renewable energy consumptions, the study applies the dynamic test of Impulse Response Function (IRF) under the VAR method. The increasing portion of renewable energy consumption in electricity generation would have no impacts on the environment. However, the hikes of renewable energy sources would incur more cost to electricity producers and shrivel up the growth of economies through the expansionary effect of industry’s consumption and private capital spending in the Germany’s economy. 相似文献
177.
Bahareh Naeimipour Elham Moniri Ali Vaziri Yazdi Raheleh Safaeijavan Hossein Faraji 《IET nanobiotechnology / IET》2022,16(6):225
In this work, the rapid, facile, and eco‐friendly green process was introduced in the preparation of β‐cyclodextrin/magnetic iron oxide nanoparticles by using the aqueous Mentha longifolia extracts of Mentha longifolia. The obtained nanoparticles were characterised by Fourier transform infrared spectroscopy, x‐ray powder diffraction, field emission scanning electron microscope, and thermogravimetric analysis. Also, effective factors on the synthesis of magnetic nanocomposites including temperature, concentration of the Mentha longifolia extract, and concentration of FeSO4 solution were optimised by Taguchi design. Moreover, important effective parameters on the adsorption efficiency; such as adsorbent dosage, pH, contact time, and temperature were investigated. The prepared magnetic nanocomposite was applied as a nanocarrier for imatinib mesylate delivery. In vitro studies confirmed imatinib mesylate release over 6 h. The nanocarrier showed pH‐dependent imatinib mesylate release with higher drug release at simulated cancer fluid (pH = 5.6) compared to neural fluid (pH = 7.4). Moreover, the sorption isotherms and kinetics for the magnetic nanocomposite were fitted into Langmuir and pseudo‐second order models, respectively. Based on the thermodynamic results, the adsorption of imatinib mesylate onto the nanoadsorbent was found to be spontaneous and exothermic. 相似文献