全文获取类型
收费全文 | 924篇 |
免费 | 203篇 |
国内免费 | 69篇 |
专业分类
电工技术 | 40篇 |
综合类 | 58篇 |
化学工业 | 441篇 |
金属工艺 | 18篇 |
机械仪表 | 40篇 |
建筑科学 | 25篇 |
矿业工程 | 21篇 |
能源动力 | 57篇 |
轻工业 | 8篇 |
水利工程 | 140篇 |
石油天然气 | 64篇 |
武器工业 | 28篇 |
无线电 | 6篇 |
一般工业技术 | 123篇 |
冶金工业 | 15篇 |
原子能技术 | 18篇 |
自动化技术 | 94篇 |
出版年
2024年 | 1篇 |
2023年 | 17篇 |
2022年 | 24篇 |
2021年 | 26篇 |
2020年 | 37篇 |
2019年 | 41篇 |
2018年 | 35篇 |
2017年 | 47篇 |
2016年 | 55篇 |
2015年 | 59篇 |
2014年 | 58篇 |
2013年 | 69篇 |
2012年 | 66篇 |
2011年 | 66篇 |
2010年 | 47篇 |
2009年 | 50篇 |
2008年 | 39篇 |
2007年 | 50篇 |
2006年 | 46篇 |
2005年 | 46篇 |
2004年 | 40篇 |
2003年 | 33篇 |
2002年 | 33篇 |
2001年 | 31篇 |
2000年 | 23篇 |
1999年 | 26篇 |
1998年 | 13篇 |
1997年 | 23篇 |
1996年 | 18篇 |
1995年 | 13篇 |
1994年 | 11篇 |
1993年 | 6篇 |
1992年 | 11篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 7篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1974年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有1196条查询结果,搜索用时 15 毫秒
61.
采用氧解吸实验,在直径190 mm的有机玻璃塔内,液相喷淋密度10~38 m3·m-2·h-1,F因子0.2~3.2 m·s-1·(kg·m-3)0.5的实验条件下测定了一种新型垂直板规整填料的流体力学及传质性能。实验结果表明:垂直板填料的操作压降及传质性能均显著优于商业波纹填料。通过与几种经改进的250型波纹填料相比发现,两者泛点F因子整体上相当;在较高液体喷淋密度下,垂直板填料传质性能及压降均高于改进250型波纹填料;在低喷淋密度下,垂直板填料可实现压降低于改进250型波纹填料,而两者传质性能相当。此外,对填料结构改进对其性能的影响进行了单因素考察。 相似文献
62.
给出新型锥-孔组合型端面密封,考虑液膜压场的变化规律与环受力变形的相互作用关系,构建机械密封3D流、固耦合数学模型,并给出相关的数值计算方法,获得了膜压分布规律及端面变形情况,分析锥面结构参数在各工况下对密封性能的影响规律。结果表明:由菱形孔所引起的动压效应可使端面产生周向和径向波状变形,而静压效应随锥度Ф和锥宽比γ的变化,在端面区域范围内所起作用也发生相应变化;对压强较低和低、中转速设备,应选取Ф=5~6或Ф=2~4的收敛锥面密封,且γ=0.8~1.0。对高压和高速设备,应选用Ф=2~3的收敛锥面密封,且γ=1.0或γ=0.2;通过改变锥面结构可有效改变机械密封的特性参数,实现密封运行中的自动调节,特别适合变工况条件。另外,由于锥面结构的变化所引起平衡系数B和膜厚h的变化,低速时可弥补动压效应较小的缺陷,获得较大开启力,也可在大h下工作,故可降低密封端面对平整度和光洁度的要求。 相似文献
63.
SHIP HYDRODYNAMICS BASIC RESEARCH IN THE UNITED STATES 总被引:3,自引:0,他引:3
Edwin P. Rood 《水动力学研究与进展(B辑)》1995,(4)
SHIPHYDRODYNAMICSBASICRESEARCHINTHEUNITEDSTATES¥EdwinP.Rood(MechanicsandEngergyConversion(333),OfficeofNavalResearchArlington... 相似文献
64.
65.
66.
对相钢在流动中性含砂氯化物中的磨损腐蚀 总被引:1,自引:0,他引:1
研究了双相钢在流动含砂的3.5%NaCl溶液中的磨损腐蚀规律,测定、分析了流动体系中的电化学阻抗谱,揭示了双相钢磨损腐蚀过程中电化学的作用及其机制。结果表明,腐蚀曜 磨损腐蚀过程中起主要作用,流体力学因素只是加速了腐蚀电化学过程,阻抗谱在低频区出现一直线段和低频收缩现象。分别是双相钢在磨损腐蚀过程中电极处于自钝化状态,并受离子在钝化膜中的扩散、迁移过程控制和电极表面局部遭受破坏的特征,对于流动体系中电化学阻抗谱的分析,曹氏阻抗理论同样适用。 相似文献
67.
Wei Feng Jianping Wen Xiaoqiang Jia Qing Yuan Yan Sun Cuiyun Liu 《American Institute of Chemical Engineers》2006,52(8):2864-2875
A coupled three-dimensional (3-D) model, combining hydrodynamics with biochemical reactions, was developed to simulate the local transient flow patterns and the dynamic behaviors of cell growth and phenol biodegradation by yeast Candida tropicalis in the bubble-column bioreactor, using the computational fluid dynamic (CFD) method. In order to validate this proposed model effectively, the validation of the local hydrodynamic characteristics of the gas-mineral salt solution (gas-liquid) two-phase system, with the phenol concentration of 1200 mg/L, and with the absence of cells, was performed in a square-sectioned bubble column bioreactor using the LDA system and conductivity probe. Furthermore, the validation of phenol biodegradation behaviors by yeast Candida tropicalis at different initial concentrations of phenol and cell was also carried out in the above bubble-column bioreactor. The results indicated that the model simulations had a satisfying agreement with the experimental data. Finally, the local instantaneous flow and phenol biodegradation features including gas holdup, gas velocity, liquid velocity, cell concentration and phenol concentration inside the bioreactor were successfully predicted in different-scale bubble columns by the proposed model. © 2006 American Institute of Chemical Engineers AIChE J, 2006 相似文献
68.
Marie-Laurence Tremblay Lingling Xu Muzaddid Sarker Xiang-Qin Liu Jan K. Rainey 《International journal of molecular sciences》2016,17(8)
Spider aciniform (wrapping) silk is a remarkable fibrillar biomaterial with outstanding mechanical properties. It is a modular protein consisting, in Argiope trifasciata, of a core repetitive domain of 200 amino acid units (W units). In solution, the W units comprise a globular folded core, with five α-helices, and disordered tails that are linked to form a ~63-residue intrinsically disordered linker in concatemers. Herein, we present nuclear magnetic resonance (NMR) spectroscopy-based 15N spin relaxation analysis, allowing characterization of backbone dynamics as a function of residue on the ps–ns timescale in the context of the single W unit (W1) and the two unit concatemer (W2). Unambiguous mapping of backbone dynamics throughout W2 was made possible by segmental NMR active isotope-enrichment through split intein-mediated trans-splicing. Spectral density mapping for W1 and W2 reveals a striking disparity in dynamics between the folded core and the disordered linker and tail regions. These data are also consistent with rotational diffusion behaviour where each globular domain tumbles almost independently of its neighbour. At a localized level, helix 5 exhibits elevated high frequency dynamics relative to the proximal helix 4, supporting a model of fibrillogenesis where this helix unfolds as part of the transition to a mixed α-helix/β-sheet fibre. 相似文献
69.
This work is essentially a review of a density functional approach in multiphase hydrodynamics developed by the authors during the last 15 years [Dinariev, J Appl Math Mech 1995;59(5):745–752; Dinariev, J Appl Math Mech 1998;62(3):397–405; Demyanov and Dinariev, Fluid Dynam 2004;39(6):933–944; Demianov et al., “Basics of the Density Functional Theory in Hydrodynamics,” Fizmatlit, Moscow; 2009 (in Russian); Dinariev and Evseev, Fluid Dynam 2010;45(1):85–95]. The basic assumption is a representation of the entropy or the Helmholtz energy of the mixture as a functional that is dependent upon chemical component densities. The hydrodynamic system of equations (local conservation laws for chemical components, momentum, and energy) is used to describe multiphase processes, and the constitutive relations (expressions for stresses, diffusion, and heat fluxes) are derived from entropy growth requirement. The authors present the results of numerical simulations describing static and dynamic multiphase systems. 相似文献
70.
ABSTRACT Results of studies on cooling and drying of powdery and granulated material in a pulsed-fluid bed ( PFB) system with relocated gas stream presented here are related to hydrodynamics and kinetics of these processes. Generalized results in the form of dimensionless equations can be used to determine basic process parameters such as drying time, heat transfer coefficient, pulsed-fluidzation velocity. pressure drop, etc. Results of experimental investigations, supplemented with experiments carried out in a prototype industrial equipment, can be useful for dryer scale-up and are recommended for designing. A comparison of technical and economic parameters of these dryers with the parameters of classical fluid-bed dryers shows many advantages of PFB systems, including, among othen. reduced gas consumption, uniform bed structure and stability of final parameters of the product. Positive estimation of the operation and technological parameters suggests that PFB dryers with relocated gas stream can be applied successfully in industrial practice. 相似文献