全文获取类型
收费全文 | 5567篇 |
免费 | 468篇 |
国内免费 | 176篇 |
专业分类
电工技术 | 291篇 |
技术理论 | 1篇 |
综合类 | 355篇 |
化学工业 | 1037篇 |
金属工艺 | 376篇 |
机械仪表 | 328篇 |
建筑科学 | 388篇 |
矿业工程 | 213篇 |
能源动力 | 142篇 |
轻工业 | 285篇 |
水利工程 | 97篇 |
石油天然气 | 380篇 |
武器工业 | 31篇 |
无线电 | 569篇 |
一般工业技术 | 755篇 |
冶金工业 | 329篇 |
原子能技术 | 62篇 |
自动化技术 | 572篇 |
出版年
2024年 | 27篇 |
2023年 | 96篇 |
2022年 | 179篇 |
2021年 | 236篇 |
2020年 | 205篇 |
2019年 | 150篇 |
2018年 | 190篇 |
2017年 | 166篇 |
2016年 | 175篇 |
2015年 | 245篇 |
2014年 | 291篇 |
2013年 | 356篇 |
2012年 | 380篇 |
2011年 | 376篇 |
2010年 | 350篇 |
2009年 | 332篇 |
2008年 | 310篇 |
2007年 | 301篇 |
2006年 | 274篇 |
2005年 | 210篇 |
2004年 | 152篇 |
2003年 | 126篇 |
2002年 | 98篇 |
2001年 | 99篇 |
2000年 | 130篇 |
1999年 | 144篇 |
1998年 | 124篇 |
1997年 | 104篇 |
1996年 | 105篇 |
1995年 | 72篇 |
1994年 | 60篇 |
1993年 | 33篇 |
1992年 | 40篇 |
1991年 | 25篇 |
1990年 | 17篇 |
1989年 | 9篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有6211条查询结果,搜索用时 15 毫秒
141.
Disperse dyes are poorly water-soluble and difficult to stably disperse in an aqueous medium, which greatly limits their application in dyeing synthetic fibers. Micronization can solve this problem. Herein, a facile way to prepare stable aqueous nanodispersions of disperse dye (C.I. disperse yellow 54) is presented by combining high-gravity antisolvent precipitation in a rotating packed bed (RPB) with spray drying. The as-prepared product had an average particle size of 120 nm, which could be readily redispersed in water. Compared with raw dye, the wettability and dispersibility of disperse dye nanoparticles were remarkably improved. Furthermore, the dyeing properties of the nanodispersions were obviously better than those of the commercial dye, which was micronized by ball milling. 相似文献
142.
通过高速摄影仪研究多孔介质通道内气液两相流体垂直向上流动的流型,在实验参数范围内依次拍摄到泡状流、弹状流、脉冲流、雾状流4种典型流型,并总结了各种流型的特征。依据实验获得的两相流动阻力数据,分别对分相模型阻力关系式和均相模型阻力关系式进行了拟合,得到了适于实验特点的两类阻力关系式。改进后的两类模型均与实验数据实现了较好的吻合,但模型关系式定义中包含了影响阻力压降各要素的均相模型具有更高的预测精度,且该模型物理意义更加清楚,可以优先用于多孔介质通道气液两相流动的阻力计算。 相似文献
143.
构建城市综合管理的标准化支撑体系 总被引:1,自引:0,他引:1
构建为城市综合管理提供支持的标准化体系和保障机制,是开展城市综合管理工作的关键,也是构建城市综合管理体制的必要环节。应通过职能部门的设置和职责划分,科学制定城市管理各个领域的标准指引,落实规范化管理,构建一套科学完整的城市管理标准化系统。业务主管部门需要建立规范的运作机制、作业制度、管理制度,制定履行城市管理职能的评价指标和奖惩标准,完善城市管理的相关法规或文件,引入数字技术等现代化手段和公众参与机制进行监督与评价,这是提高城市综合管理体制可行性和有效性的合理路径。 相似文献
144.
将模态分析的新方法试验模态与解析模态的综合技术应用于建筑结构动力计算,解决高层建筑的动力特性分析问题,此法将复杂结构化成子结构,达到“化整为零,积零为整”的目的.算例表明,计算精度高,用于工程可得到比较满意的结果. 相似文献
145.
原岩应力的边界元位移反分析确定方法 总被引:1,自引:0,他引:1
围岩位移量在岩石地下工程中比较容易测得,利用数值计算方法通过反分析的手段可以由位移反算出原岩应力,并通过边界元法阐述了原岩应力位移反分析法的原理。 相似文献
146.
147.
Ouwen Zhai Helene Baust Dr.-Ing. Marco Gleiß Prof. Dr.-Ing. Hermann Nirschl 《化学,工程师,技术》2023,95(1-2):189-198
The scale up of solid bowl centrifuges is a major challenge as the process and material behavior are complex and difficult to describe. A common approach to forecast the process behavior is to use analytical models and transfer the experience gained from the lab to the industrial scale. In this context, time-consuming and cost-intensive pilot scale experiments are necessary. This paper presents a methodology to improve the scale up process and make it more sustainable by using a numerical model that allows the real-time tracking of the process and a more reliable scale up process. For this approach, the material behavior is derived from laboratory experiments whereby the scalability is given. Here, the determination of material functions allows an accurate representation of the material behavior for solid bowl centrifuges of different scales. The focus of this paper is the detailed explanation of material related functions for the scale up of decanter centrifuges. 相似文献
148.
Lanlan Zhai Ruowang Liu Feng Peng Yunhao Zhang Kai Zhong Jixin Yuan Yunjun Lan 《应用聚合物科学杂志》2013,128(3):1715-1724
A novel method was used to synthesis nanosilica/waterborne polyurethane (WPU) hybrids by in situ hydrolysis and condensation of tetraethyl orthosilicate (TEOS) and/or 3‐aminopropyltriethoxylsilane bonding at the end of the WPU molecular chain. The hybrid was characterized by scanning electron microscopy, energy dispersive spectroscopy (EDS), transmission electron microscopy, Fourier transform infrared spectroscopy (FTIR), and X‐ray photoelectron spectroscopy (XPS). The results showed that the nanosilica/WPU hybrids with well‐dispersed nanosilica particles were synthesized, in which the particles had typical diameters of about 50 nm. In addition, XPS and FTIR analyses demonstrated that chemical interaction occurred between WPU and silica. The effects of TEOS on surface wettability, water resistance, mechanical strength, and thermal properties of the hybrid were also evaluated by contact angle measurements, water absorption tests, mechanical tests, and differential scanning calorimetry, respectively. An increase in advancing contact angles, water resistance, and tensile strength, as well as decrease in elongation at break and glass transition temperature, were obtained with the addition of TEOS. Water absorption decreased from 17.3 to 5.5%. The tensile strength increased to a maximum of 29.7 MPa, an increase of about 34%. Elongations at break of the hybrids decreased 191%. These results were attributed to the effects of the nanosilica and the chemical interaction between WPU and silica. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
149.
This study focuses on an improved synthesis of a branched poly (ethylene imine) (PEI)‐modified cellulose‐based adsorbent (Cell‐g‐PGMA‐PEI). We aim to improve the adsorbent capacity by reducing side reaction of epoxide ring opening during graft copolymerization of glycidyl methacrylate (GMA) onto cellulose which increases the content of epoxy groups, anchors to immobilize branched PEI moieties. FTIR spectra provided the evidence of successful graft copolymerization of GMA onto cellulose initiated by benzoyl peroxide (BPO) and modification with PEI. The amount of epoxy groups of Cell‐g‐PGMA was 4.35 mmol g?1 by epoxy titration. Subsequently, the adsorption behavior of Cu(II) on cell‐g‐PGMA‐PEI in aqueous solution has been investigated. The data from the adsorption kinetic experiments agreed well with pseudo‐second‐order model. The adsorption isotherms can be interpreted by the Langmuir model with the maximum adsorption capacity of 102 mg g?1 which was largely improved compared with the similar adsorbent reported. The dynamic adsorption capacity obtained from the column tests was 119 mg g?1 and the adsorbent could be regenerated by HCl of 0.1 mol L?1. Results indicate that the novel pathway for the synthesis of Cell‐g‐PGMA‐PEI exhibits significant potential to improve the performance of adsorbents in removal and recovery of Cu(II) from aqueous solution. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
150.