全文获取类型
收费全文 | 19835篇 |
免费 | 2271篇 |
国内免费 | 1570篇 |
专业分类
电工技术 | 1800篇 |
技术理论 | 3篇 |
综合类 | 1841篇 |
化学工业 | 2167篇 |
金属工艺 | 516篇 |
机械仪表 | 2075篇 |
建筑科学 | 747篇 |
矿业工程 | 347篇 |
能源动力 | 362篇 |
轻工业 | 353篇 |
水利工程 | 329篇 |
石油天然气 | 275篇 |
武器工业 | 150篇 |
无线电 | 1961篇 |
一般工业技术 | 1676篇 |
冶金工业 | 1169篇 |
原子能技术 | 164篇 |
自动化技术 | 7741篇 |
出版年
2024年 | 61篇 |
2023年 | 222篇 |
2022年 | 342篇 |
2021年 | 442篇 |
2020年 | 502篇 |
2019年 | 432篇 |
2018年 | 453篇 |
2017年 | 646篇 |
2016年 | 731篇 |
2015年 | 789篇 |
2014年 | 1081篇 |
2013年 | 1209篇 |
2012年 | 1335篇 |
2011年 | 1578篇 |
2010年 | 1125篇 |
2009年 | 1267篇 |
2008年 | 1245篇 |
2007年 | 1412篇 |
2006年 | 1254篇 |
2005年 | 1126篇 |
2004年 | 1037篇 |
2003年 | 874篇 |
2002年 | 735篇 |
2001年 | 613篇 |
2000年 | 514篇 |
1999年 | 402篇 |
1998年 | 334篇 |
1997年 | 295篇 |
1996年 | 234篇 |
1995年 | 210篇 |
1994年 | 178篇 |
1993年 | 133篇 |
1992年 | 143篇 |
1991年 | 75篇 |
1990年 | 89篇 |
1989年 | 80篇 |
1988年 | 72篇 |
1987年 | 57篇 |
1986年 | 40篇 |
1985年 | 51篇 |
1984年 | 47篇 |
1983年 | 26篇 |
1982年 | 28篇 |
1981年 | 17篇 |
1980年 | 16篇 |
1979年 | 15篇 |
1978年 | 7篇 |
1977年 | 11篇 |
1976年 | 10篇 |
1955年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Investigation on the miniaturized parallel multichannel-based devices packed with glass beads to improve the mass exchange execution is the critical focal point of the current study. One of the essential parameters to specify the miniaturized devices' flow distribution is the residence time distribution (RTD). In the present context, the RTDs of a liquid tracer were investigated for the air-water multiphase flows (concurrent) across the multichannel-based miniaturized devices (comprising of 11 similar dimensional parallel channels). The devices were variable in height and packed with glass beads. The conductivity estimations generated the RTD curves and were addressed by the axial dispersion model (ADM). The fluid-flow rates differed within the range of 5–23 ml min−1. The axial dispersion coefficients and the rate of the specific energy dispersion were investigated. The effects of pressure difference and geometry on the hydrodynamic attributes and mixing properties were well-illustrated, and the new correlations were suggested. 相似文献
2.
《Advanced Powder Technology》2022,33(11):103627
Naringin (NAR), a major flavanone (FVA) glycoside, is a component of food mainly obtained from grapefruit. We used NAR as a food additive to improve the solubility and permeability of hydrophobic polyphenols used as supplements in the food industry. The spray-dried particles (SDPs) of NAR alone show an amorphous state with a glass transition temperature (Tg) at 93.2 °C. SDPs of hydrophobic polyphenols, such as flavone (FVO), quercetin (QCT), naringenin (NRG), and resveratrol (RVT) were prepared by adding varying amounts of NAR. All SDPs of hydrophobic polyphenols with added NAR were in an amorphous state with a single Tg, but SDPs of hydrophobic polyphenols without added NAR showed diffraction peaks derived from each crystal. The SDPs with NAR could keep an amorphous state after storage at a high humidity condition for one month, except for SDPs of RVT/NAR. SDPs with NAR enhanced the solubility of hydrophobic polyphenols, especially NRG solubility, which was enhanced more than 9 times compared to NRG crystal. The enhanced solubility resulted in the increased membrane permeability of NRG. The antioxidant effect of the hydrophobic NRG was also enhanced by the synergetic effect of NAR. The findings demonstrated that NAR could be used as a food additive to enhance the solubility and membrane permeability of hydrophobic polyphenols. 相似文献
3.
4.
5.
AbstractIndustry 4.0 aims at providing a digital representation of a production landscape, but the challenges in building, maintaining, optimizing, and evolving digital models in inter-organizational production chains have not been identified yet in a systematic manner. In this paper, various Industry 4.0 research and technical challenges are addressed, and their present scenario is discussed. Moreover, in this article, the novel concept of developing experience-based virtual models of engineering entities, process, and the factory is presented. These models of production units, processes, and procedures are accomplished by virtual engineering object (VEO), virtual engineering process (VEP), and virtual engineering factory (VEF), using the knowledge representation technique of Decisional DNA. This blend of the virtual and physical domains permits monitoring of systems and analysis of data to foresee problems before they occur, develop new opportunities, prevent downtime, and even plan for the future by using simulations. Furthermore, the proposed virtual model concept not only has the capability of Query Processing and Data Integration for Industrial Data but also real-time visualization of data stream processing. 相似文献
6.
7.
8.
针对平面并联机构无奇异位置工作空间求解困难、过程繁琐、计算量大等问题,提出了基于CAD求解平面并联机构工作空间的三维螺旋扫描方法。将[n]自由度平面并联机构分解成[n]条支链进行独立分析,得到每条支链下末端执行器的可达区域,再将所有支链可达区域取交集即为平面并联机构工作空间。应用SolidWorks软件建立平面并联机构模型,进行几何特征处理,通过自动求解器求解,将求解过程图形化,快速得到同轴布局5R机构和平面3-RPR并联机构的无奇异位置工作空间。通过同轴布局5R机构的运动学实验,验证了该求解方法的可行性。 相似文献
9.
《Ceramics International》2022,48(11):15268-15273
SiC/SiC mini-composites reinforced with SiC fibers coated with different numbers of ZrSiO4 sublayers prepared via a non-hydrolytic sol-gel process were fabricated. The tensile strength and work of fracture of the prepared SiC/SiC mini-composites were determined, and the relationship between their mechanical properties and fracture morphologies was discussed. The toughening mechanism and the variation tendency of their mechanical properties were further elaborated by analyzing the interfacial debonding morphologies of the SiC/SiC mini-composites with 1 and 4 layers of ZrSiO4 interphase as well as the results of prior studies. A relatively rare phenomenon—the delamination of the multilayer ZrSiO4 interphase in the SiC/SiC mini-composites but not on the SiC fibers—was observed, which clearly demonstrated the weak bonding between the ZrSiO4 sublayers in the SiC/SiC mini-composites. The ZrSiO4 sublayer delamination mechanism was then explained based on the high-magnification morphologies found in and beside the ZrSiO4 interphase. 相似文献
10.
A hybrid fluidized-bed bioreactor for water purification was proposed and analyzed. It is a novel type of bioreactor characterized by hitherto unknown stationary and dynamic features. Steady-state characteristics of this hybrid bioreactor with external liquid circulation are presented. A quantitative analysis of steady-state properties of the bioreactor was performed with the aid of an original mathematical model developed for a double-substrate aerobic microbiological process. A steady-state analysis of aerobic processes characterized by different oxygen demand was performed. The effect of essential parameters was evaluated, including carbonaceous substrate concentration in the feed stream to the apparatus, aeration intensity, total residence time of a liquid in the bioreactor, and height of the bed of fine carrier particles. 相似文献