全文获取类型
收费全文 | 141篇 |
免费 | 12篇 |
专业分类
化学工业 | 31篇 |
金属工艺 | 1篇 |
机械仪表 | 2篇 |
建筑科学 | 3篇 |
能源动力 | 9篇 |
轻工业 | 13篇 |
石油天然气 | 1篇 |
无线电 | 8篇 |
一般工业技术 | 14篇 |
冶金工业 | 57篇 |
原子能技术 | 1篇 |
自动化技术 | 13篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2021年 | 6篇 |
2020年 | 7篇 |
2019年 | 3篇 |
2018年 | 7篇 |
2017年 | 9篇 |
2016年 | 5篇 |
2015年 | 3篇 |
2014年 | 11篇 |
2013年 | 9篇 |
2012年 | 4篇 |
2011年 | 2篇 |
2010年 | 6篇 |
2009年 | 2篇 |
2008年 | 7篇 |
2006年 | 5篇 |
2005年 | 5篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 6篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 9篇 |
1997年 | 8篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1978年 | 1篇 |
排序方式: 共有153条查询结果,搜索用时 234 毫秒
71.
Ilmatar Rooda Mohammad Mehedi Hasan Kristine Roos Janeli Viil Aneta Andronowska Olli-Pekka Smolander Ülle Jaakma Andres Salumets Alireza Fazeli Agne Velthut-Meikas 《International journal of molecular sciences》2020,21(24)
Cell-free RNAs have the potential to act as a means of gene expression regulation between cells and are therefore used as diagnostic markers describing the state of tissue environment. The origin and functions of such RNAs in human ovarian follicle, the environment of oocyte maturation, are unclear. The current study investigates the difference in the microRNA profiles of fertile women and polycystic ovary syndrome (PCOS) patients in three compartments from the same preovulatory follicle: mural granulosa cells (MGC), cell-free follicular fluid (FF), and extracellular vesicles (EV) of the FF by small RNA sequencing. In silico analysis was used for the prediction and over-representation of targeted pathways for the detected microRNAs. PCOS follicles were distinguished from normal tissue by the differential expression of 30 microRNAs in MGC and 10 microRNAs in FF (FDR < 0.1) that commonly regulate cytokine signaling pathways. The concentration of EV-s was higher in the FF of PCOS patients (p = 0.04) containing eight differentially expressed microRNAs (p < 0.05). In addition, we present the microRNA profiles of MGC, FF, and EV in the fertile follicle and demonstrate that microRNAs loaded into EVs target mRNAs of distinct signaling pathways in comparison to microRNAs in FF. To conclude, the three follicular compartments play distinct roles in the signaling disturbances associated with PCOS. 相似文献
72.
Gas‐liquid direct‐contact evaporators are characterized by the bubbling of a superheated gas through the solution to be concentrated. In other words, they are nonisothermal bubble columns. Despite their simplicity of construction, these units exhibit rather complex hydrodynamics and, similar to what occurs to isothermal bubble columns, the design of such units still poses a problem. The present paper reviews the literature regarding this kind of equipment, addressing both experimental studies and modeling efforts. The covered issues include classic and potential applications, bubbling regimes, gas holdup and bubble size distributions, as well as mathematical models proposed for simulating the unit. Additionally, pertinent literature on isothermal bubble columns is also discussed. Recommendations are made for future research. 相似文献
73.
74.
A transient two-fluid model is applied to simulate fluid flow and heat transfer in a nonisothermal water model of continuous
casting (CC) tundish. The original liquid in the bath is defined as the first fluid, and the inlet stream, with the temperature
variation, is defined as the second fluid. The flow patterns and heat transfer are predicted by solving the three-dimensional
(3-D) transient transport equations for each fluid. The results predicted by the two-fluid model make the effect of natural
convection more clear compared with the generally used single fluid model k-ɛ turbulence model. 相似文献
75.
Structural and Optical Properties of Highly Nd-Doped Yttrium Aluminum Garnet Ceramics from Alkoxide and Glycolate Precursors 总被引:1,自引:0,他引:1
Sanjay Mathur Hao Shen Michael Veith Rasa Rapalaviciute Thomas Agne 《Journal of the American Ceramic Society》2006,89(6):2027-2033
Yttrium aluminum garnet (YAG) nanopowders doped with high neodymium (Nd) content (3 at.%) were synthesized by the sol–gel processing of (i) alkoxide precursors and (ii) metal chelates formed by complexing the cations with polyethylene glycol. A stoichiometric YAG composition was obtained following both procedures; however, the agglomeration of particles was significantly higher in glycolate synthesis, which shielded residual organics from oxidation (elemental analyses). Distribution of Nd3+ ions in the YAG matrix, as shown by the absorption of pump energy and photoluminescence spectra of Nd:YAG ceramics, was more homogeneous in alkoxide-derived powders. The segregation of Nd centers in the glycolate-derived sample was supported by the precipitation of a crystalline Nd2 O3 phase (X-ray diffraction) during sintering. High-resolution absorption spectra (4 I9/2 (1)→4 F9/2 (1)) of the powders showed that a higher absorption cross-section of glycolate-derived powders is due to Nd3+ –Nd3+ ion pairing, which leads to the quenching of photoluminescence. Owing to the better dispersion of optically active centers, the photoluminescence signal was found to be substantially enhanced in alkoxide-derived Nd:YAG ceramics. 相似文献
76.
João F. Mitre Paulo L.C. Lage Marcos A. Souza Eli Silva Luiz Fernando Barca Antonio O.S. Moraes Raquel C.C. Coutinho Elizabeth F. Fonseca 《Chemical Engineering Research and Design》2014
An experimental and theoretical study was carried out regarding the evolution of droplet size distributions for the flow of water in oil emulsions through a valve-like element that simulates a mixing valve. The water droplets had diameters in the 0.1–100 μm range, which includes droplets that are either smaller or larger than the Kolmogorov length scale for the experimental conditions. Droplet breakage and coalescence models that can be used for this size range were proposed. A simplified population balance model was developed to interpret the experimental data and solved by the method of classes. The model parameters were estimated by the orthogonal distance regression method. The simplifying assumption of the model was verified by global optimization using a parallel implementation of the particle swarm optimization method. The agreement between simulated and experimental droplet volume size distributions was good. The predictions of the DeBroukere mean diameter, d43, were unbiased with mean errors of 8%. 相似文献
77.
78.
Concentration gradients of inclusions during inductive and gas stirring of AISI H13 tool steel in a ladle have been studied using a unique experimental technique at Uddeholm Tooling AB in Sweden. A specially designed sampling equipment, which allows five samples to be taken at the same time and at different depths was used. The aim was to experimentally quantify the existence of inclusion size population gradients in different positions of the steel melt. One experiment was carried out using induction stirring and one using gas stirring. The main findings from the induction stirring experiment was that i) concentration gradients of inclusions exist, ii) the number of inclusions decreases with stirring time in all positions, and iii) that the superficial positions show a more rapid decrease than the deeper ones. The main findings from the gas stirring experiment are that i) concentration gradients of inclusions exist, ii) the superficial positions are mostly affected by the gas plumes, and show a very pronounced decrease of the number of inclusions with stirring time, and iii) the deeper positions and also one of the superficial position (no “3”) shows no decreasing trend. 相似文献
79.
Although considerable progress has been made in the understanding of the biology of gestational trophoblastic tumors, future generations will undoubtedly classify our current knowledge base as basic. It is our hope that by more precisely defining the genetic basis for these diverse lesions, we may be able to develop better diagnostic, surveillance, and treatment modalities for affected patients. 相似文献
80.
The continuous kinetic lumping models are traditionally solved by methods that discretize the mixture into a large number of pseudo-components. This works proposes the usage of the adaptive characterization of continuous mixtures, grounded on the direct quadrature method of generalized moments, in the solution of kinetic lumping models, which allows a large reduction in the number of pseudo-components. Catalytic hydrogenation and hydrocracking problems were used to evaluate this methodology, comparing its results with analytical solutions or results from a classical numerical method. The results showed that the proposed methodology could accurately solve those continuous kinetic models using a small number of adaptive pseudo-components, leading to a large reduction in the computational cost of simulation when compared to the classical numerical method. 相似文献