全文获取类型
收费全文 | 3147篇 |
免费 | 286篇 |
国内免费 | 172篇 |
专业分类
电工技术 | 121篇 |
综合类 | 193篇 |
化学工业 | 574篇 |
金属工艺 | 196篇 |
机械仪表 | 197篇 |
建筑科学 | 239篇 |
矿业工程 | 94篇 |
能源动力 | 90篇 |
轻工业 | 264篇 |
水利工程 | 53篇 |
石油天然气 | 280篇 |
武器工业 | 34篇 |
无线电 | 260篇 |
一般工业技术 | 377篇 |
冶金工业 | 166篇 |
原子能技术 | 35篇 |
自动化技术 | 432篇 |
出版年
2024年 | 10篇 |
2023年 | 44篇 |
2022年 | 106篇 |
2021年 | 126篇 |
2020年 | 102篇 |
2019年 | 93篇 |
2018年 | 96篇 |
2017年 | 81篇 |
2016年 | 100篇 |
2015年 | 118篇 |
2014年 | 133篇 |
2013年 | 173篇 |
2012年 | 211篇 |
2011年 | 205篇 |
2010年 | 200篇 |
2009年 | 182篇 |
2008年 | 177篇 |
2007年 | 165篇 |
2006年 | 176篇 |
2005年 | 155篇 |
2004年 | 113篇 |
2003年 | 112篇 |
2002年 | 102篇 |
2001年 | 99篇 |
2000年 | 97篇 |
1999年 | 77篇 |
1998年 | 62篇 |
1997年 | 62篇 |
1996年 | 42篇 |
1995年 | 46篇 |
1994年 | 35篇 |
1993年 | 23篇 |
1992年 | 28篇 |
1991年 | 6篇 |
1990年 | 8篇 |
1989年 | 9篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有3605条查询结果,搜索用时 328 毫秒
101.
A reflective fiber temperature sensor system based on the ZnO thin film is proposed. The transmittance spectra and temperature dependent optical property of the sensing head with ZnO thin film is investigated theoretically and experimentally, and the temperature resolution of ~1?°C is obtained in the temperature region of 300-773 K. The temperature sensing system is only related to the wavelength shift of transmittance spectra, and has a high stability without depending on the incident light intensity. This research results also indicate a fiber optical sensor with a broad temperature measurement range (10-1800 K) can be gained as a promising temperature sensing device, and can be applied into some extremely environments, such as aircraft, nuclear power station and power transmission system, and so on. 相似文献
102.
103.
Chenghua Sui Shengjie Wo Pinggen Cai Nan Gao Danyang Xu Yonghao Han 《Journal of Modern Optics》2017,64(21):2413-2419
Corneal topography provides powerful support in the diagnosis and treatment of corneal disease by displaying the corneal surface topography in data or image format. To realize the precise detection of corneal surface topography, an optical system for the corneal topography that is based on a Placido disc is designed, which includes a ring distribution on a Placido disc, an imaging system and a collimating illumination system. First, a mathematical model that is based on the corneal topography working principles is established with MATLAB to determine the distribution of white-and-black rings on the Placido disc, in which the ellipsoid facial rings-target of the Placido disc is utilized. Second, the imaging lens structure is designed and optimized by Zemax software. Last, the collimating illumination lens structure is designed by paraxial ray trace equations. The quality of the corneal topography, which is based on our designed optical system, is evaluated. The high-contrast image of uniformly distributed white-and-black rings is observed through the CCD camera. Our optical system for the corneal topography has high precision, with a measuring region of the cornea with a diameter of approximately 10 mm. Therefore, the creation of this optical system offers guidance for designing and improving the optical system of Placido-disc topography. 相似文献
104.
Kaihua Su Xianyong Yao Sheng Sui Zhaoxu Wei Junliang Zhang Shangfeng Du 《International Journal of Hydrogen Energy》2014
The effects of ionomer contents were investigated in composite electrodes with in-situ grown single crystal Pt nanowires (Pt-NWs) for PEMFCs, including the amount in the carbon matrix and impregnated on the surface of the electrocatalyst layer. The electrocatalyst layer was prepared by growing Pt-NWs directly on the carbon matrix with a simple one-step wet chemical approach at room temperature. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), polarization curve tests, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) were employed to evaluate the ionomer effects. The experimental results showed that the ionomer in the carbon matrix had an influence on the ionic conductivity and aggregation and distribution of the Pt-NWs, and the ionomer impregnated on the surface of the electrocatalyst layer affected the mass transport and ionic conductivity. The performance of the MEA was improved by optimizing the ionomer contents. 相似文献
105.
Yan Huang Honggang Lu Bingnan Wang Wenbo He Hongzhou Dong Lina Sui Zhixing Gan Shuai Ma Beili Pang Lifeng Dong Liyan Yu 《International Journal of Hydrogen Energy》2021,46(5):3530-3538
As a promising catalyst for solar hydrogen production, black phosphorus (BP) has received widespread attention due to variable band gaps, high carrier mobility, and strong light absorption performance. Herein, we use MoS2 as a cocatalyst to synthesize BP/MoS2 catalyst with polycrystalline BP to improve photocatalytic performance under visible light irradiation. A small amount of MoS2 can reduce the recombination of electron-hole pairs in the composite, increase carrier transport efficiency, and then improve photocatalytic performance. As expected, the 10/0.5 ratio of BP/MoS2 catalyst exhibits the highest photocatalytic hydrogen evolution performance with a hydrogen evolution rate of 575.4 μmol h?1 g?1, which is 2.5 times of pure BP. Based on the results above, a simple method is provided to synthesize low-cost black phosphorus-based photocatalysts. 相似文献
106.
《卫合德堂图记》是一张广州沥滘村的手绘平面地图,在民国十七年的《一万分一广州市全图》基础上绘成。文章通过对“图”和“谱”的阅读和比较,解读了水系、庙坛和祠堂在村落形态结构的主导作用,讨论了沥滘村罗氏和卫氏两大宗族的构建以及在枝状水系条件下村落形态的发展。 相似文献
107.
Ge Zhang Zhan Sui Benxue Jiang Yiguang Jiang Shuilin Chen Long Zhang 《Journal of the European Ceramic Society》2019,39(15):5030-5035
A pure yttrium aluminum garnet (YAG) ceramic/YAG single crystal composite material is prepared using the optimized solid-state crystal growth (SSCG) method. The micropores on the bonding interface of the composite sample are eliminated for the first time during the SSCG process and the transmittance is very close to the theoretical value, which reached 83.14% at 1064 nm. Meanwhile, the mechanism of elimination and migration of the pores under high temperature is studied. Additionally, the single crystal growth rate has significantly improved and the time of composite sample preparation has also significantly reduced proving that the SSCG method is an effective method for producing high quality composite material. 相似文献
108.
109.
Yingnan Zhu Jiamin Zhang Jiayin Song Jing Yang Zheng Du Weiqiang Zhao Hongshuang Guo Chiyu Wen Qingsi Li Xiaojie Sui Lei Zhang 《Advanced functional materials》2020,30(6)
Diabetic ulcer is the most common kind of chronic wound worldwide. Though great efforts have been devoted, diabetic ulcer still remains as a challenge that requires constant monitoring and management. In this work, a multifunctional zwitterionic hydrogel is developed to simultaneously detect two fluctuant wound parameters, pH and glucose level, to monitor the diabetic wound status. A pH indicator dye (phenol red) and two glucose sensing enzymes, glucose oxidase (GOx) and horseradish peroxidase (HRP), are encapsulated in the anti‐biofouling and biocompatible zwitterionic poly‐carboxybetaine (PCB) hydrogel matrix. The visible images are collected by a smartphone and transformed into RGB signals to quantify the wound parameters. Results show that the activity and stability of both two enzymes are improved within PCB hydrogel, and the Kcat/Km value of PCB‐HRP is ≈5.5 fold of free HRP in artificial wound exudate. This novel wound dressing can successfully monitor the pH range of 4–8 and glucose level of 0.1–10 × 10?3 m . Meanwhile, it also provides a moist healing environment that can promote diabetic wound healing. This multifunctional wound dressing may open vistas in chronic wound management and guide the diabetes treatment in clinical applications. 相似文献
110.
Physicochemical and structural characteristics of starches from Chinese hull‐less barley cultivars 下载免费PDF全文
Xiangli Kong Stefan Kasapis Ping Zhu Zhongquan Sui Jinsong Bao Harold Corke 《International Journal of Food Science & Technology》2016,51(2):509-518
Fourteen hull‐less barley cultivars, collected from four major cultivated areas in China, were employed to investigate the structural and physicochemical properties of their starches in this study. Relatively wide variations in physicochemical properties of the starches were observed. Amylose content ranged from 23.1% to 30.0%, swelling power and water solubility index ranged from 12.8 to 19.9 g g?1 and 12.7% to 23.7% respectively. Peak viscosity was from 170 to 346 Rapid Visco Unit (RVU), peak temperature (Tp) of starch gelatinisation was from 55.6 to 61.8 °C and enthalpy of starch retrogradation ranged from 0.3 to 3.1 J g?1. Weight‐based chain‐length proportions of fa, fb1, fb2 and fb3 in amylopectins ranged from 21.65% to 24.95%, 44.48% to 49.44%, 15.56% to 17.19% and 9.83% to 16.66% respectively. Correlation analyses showed that amylose content was inversely related to pasting parameters and enthalpy of gelatinisation. Pasting properties and amylopectin structures were the most important parameters to differentiate starch properties among different hull‐less barley cultivars in this study. This work will be useful for exploring applications of Chinese hull‐less barley starches in food and non‐food industries. 相似文献