全文获取类型
收费全文 | 3100篇 |
免费 | 209篇 |
国内免费 | 50篇 |
专业分类
电工技术 | 25篇 |
综合类 | 157篇 |
化学工业 | 598篇 |
金属工艺 | 137篇 |
机械仪表 | 118篇 |
建筑科学 | 205篇 |
矿业工程 | 72篇 |
能源动力 | 88篇 |
轻工业 | 325篇 |
水利工程 | 28篇 |
石油天然气 | 151篇 |
武器工业 | 15篇 |
无线电 | 303篇 |
一般工业技术 | 384篇 |
冶金工业 | 57篇 |
原子能技术 | 56篇 |
自动化技术 | 640篇 |
出版年
2025年 | 15篇 |
2024年 | 37篇 |
2023年 | 58篇 |
2022年 | 58篇 |
2021年 | 87篇 |
2020年 | 112篇 |
2019年 | 81篇 |
2018年 | 95篇 |
2017年 | 88篇 |
2016年 | 94篇 |
2015年 | 123篇 |
2014年 | 196篇 |
2013年 | 193篇 |
2012年 | 214篇 |
2011年 | 211篇 |
2010年 | 155篇 |
2009年 | 158篇 |
2008年 | 146篇 |
2007年 | 154篇 |
2006年 | 135篇 |
2005年 | 148篇 |
2004年 | 121篇 |
2003年 | 127篇 |
2002年 | 88篇 |
2001年 | 61篇 |
2000年 | 70篇 |
1999年 | 59篇 |
1998年 | 50篇 |
1997年 | 39篇 |
1996年 | 38篇 |
1995年 | 38篇 |
1994年 | 22篇 |
1993年 | 17篇 |
1992年 | 15篇 |
1991年 | 7篇 |
1990年 | 9篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 5篇 |
1983年 | 8篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1978年 | 1篇 |
排序方式: 共有3359条查询结果,搜索用时 15 毫秒
61.
通过对信号传输理论、竞争-冒险现象和物理不可克隆函数(Physical Unclonable Functions, PUF)电路的研究,论文提出一种基于信号传输理论的毛刺型物理不可克隆函数电路(Glitch Physical Unclonable Functions, Glitch-PUF)方案。该方案首先根据偏差延迟的信号传输理论,推导出获得稳定毛刺输出的电路级数;然后利用组合逻辑电路的传播延迟差异,结合1冒险和0冒险获得具有毛刺的输出波形,采用多级延迟采样电路实现Glitch-PUF的输出响应。由于毛刺信号具有显著的非线性特性,将其应用于PUF电路可有效解决模型攻击等问题。最后在TSMC 65 nm CMOS工艺下,设计128位数据输出的电路结构,Monte Carlo仿真结果表明Glitch-PUF电路具有良好的随机性。 相似文献
62.
以榛子为原料,通过压榨、索氏提取和超声波辅助法提取榛子油。以榛子油的得率为评价指标,通过单因素试验优化了提取工艺,并对榛子油的理化性质、脂肪酸组成、元素组成及主要官能团进行分析,以比较不同提取方法对榛子油成分和性质的影响。结果表明:超声波辅助法提取榛子油的最佳工艺条件为超声温度60℃、超声时间50min、液料比10:1(mL:g)和超声波功率480W,榛子油得率为64.97%;索氏法提取榛子油的最佳工艺条件为提取时间4h、提取温度84℃、料液比、榛子油得率为62.93%;压榨法提取榛子油前需要对榛子进行烘干,烘干时间40min,榛子油得率为45.90%。对榛子油的理化性质、油脂中金属元素及脂肪酸组成进行了研究,榛子油中主要有磷、锌、镁、钾、钙等元素,榛子油的脂肪酸主要由顺油酸、花生酸、顺亚油酸、棕榈酸、硬脂酸、棕榈一烯酸、十八碳三烯酸、花生一烯酸和十七碳酸组成,其中顺油酸和顺亚油酸GC含量最高,二者之和达92%以上。 相似文献
63.
Ana Paula Macedo ;Debora Taffarel Ferrari ;Roberta C Shimano ;Joao Paulo Mardegan Issa ;Alceu Afonso Jordao ;Antonio Carlos Shimano 《机械工程与自动化:英文版》2014,(6):542-546
The aim of this study is to evaluate the ability of physical training in the maintenance of muscle strength in rats with HFD (high-fat diet) after OVX (ovariectomy). Eighty Wistar rats are at eight weeks of age and weight 200 g which divided into 8 groups (n = 10) and treated for 12 weeks: GA: OVX + ND (normal diet), GB: OVX + ND + training, GC: sham + ND, GD: sham + ND + training, GE: OVX + HFD, GF: OVX + HFD + training, GG: sham + HFD and GH: sham + HFD + training. HFD consists of standard ration for rats with addition of 30% lipids. In training groups, physical training five training/week was conducted on a treadmill with adaptation period of three weeks up to 18 m/s for one hour, training were performed for 12 weeks. The sedentary animals remained in individual box. To analyze the effects of training and diet, tensile strength tests of the gastrocnemius muscles were conducted: the speed of 0.1 mm/min. Analysis of variance was performed to compare groups. The mean (SD) obtained for the maximum load (N) were: GA 57.77 (6.89), GB 62.74 (5.07), GC 49.45 (6.06), GD 59.42 (5.26) and GE 55.58 (4.72), GF 62.50 (4.56), GG 58.35 (4.54) and GH 56.67 (5.87), respectively. There were no differences for maximum load between surgeries (p = 0.004) and between treatments (p = 0.000). Differences were found also for the relationship surgery diet treatment (p = 0.007). For the variable stiffness (N/mm), there were not statistically significant differences: GA 5.03 (0.72), GB 5.08 (1.09), GC 5.17 (0.53), GD 5.35 (0.80), GE 5.52 (1.20), GF 5.36 (1.07), GG 4.83 (1.03) and GH 5.40 (0.73). For the toughness (N/mm), there were differences between treatments (p = 0.010) and the ratio diet treatment (p = 0.024): GA 455.00 (107.21), GB 541.96 (126.80), GC 394.97 (84.67), GD 566.90 (157.07); GE 424.63 (113.03), GF 478.07 (106.03); GG 517.44 (98.65? 相似文献
64.
高岭土深加工技术研究的进展 总被引:7,自引:0,他引:7
较全面地介绍了高岭土的纯化处理、超微粉碎、煅烧和表面改性处理的试验研究和应用情况,为推动高岭土深加工技术的研究和开发提供了有效方法。 相似文献
65.
66.
Dongqing Zeng Zhanhong Yang Shengwei Wang Xia Ni Dengjun Ai Qingqing Zhang 《Electrochimica acta》2011,(11):4075
In-doped ZnO (IZO) samples were synthesized by a simple co-precipitation method. X-ray diffraction (XRD) patterns, Raman spectra and scanning electron microscopy (SEM) images show that IZO with 2.5 wt% In2O3 has a pure wurtzite structure and a plate-like morphology. IZO with 16.3 wt% In2O3 (theoretical value) mainly shows a wurtzite structure. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge–discharge measurement were utilized to examine the electrochemical performances of IZO with 2.5 wt% In2O3 as anode material for Ni–Zn simulated cells. Compared with the physical mixture of ZnO with In2O3, IZO increases the charge-transfer resistance of zinc electrode. Furthermore, the initial discharge capacity of IZO is 569 mAh g−1, and the discharge capacity decays slightly with the capacity retention ratio of 95.2% over 73 cycles, which is much higher than that of the physical mixture of ZnO with In2O3. 相似文献
67.
Tong Zhang Bin Cao Yilin Fan Yves Gonthier Lingai Luo Shudong Wang 《Chemical engineering science》2011,(23):5791
This paper presents an experimental investigation on influence of liquid physical properties and channel diameter on gas–liquid flow patterns in horizontal circular microchannels with inner diameters of 302, 496 and 916 μm. Several liquids with different physical properties, i.e. water, ethanol, three sodium carboxymethyl cellulose (CMC) solutions (0.0464%, 0.1262%, 0.2446% CMC) and two sodium dodecyl sulfate (SDS) solutions (0.0608%, 0.2610% SDS) are chosen as working fluid and nitrogen as working gas. By using a high-speed photography system, flow patterns such as bubbly flow, slug and unstable slug flow, churn flow, slug-annular and annular flow are observed and identified on the flow regime maps. The results show that the liquid physical properties (viscosity and surface tension) and channel diameter affect the flow pattern transitions remarkably. Comparison with existing models in literature implies that these transitions cannot be well predicted. As a result, an effort is put into the proposition of a new empirical model taking the effects of channel size and liquid physical properties into account. 相似文献
68.
物理化学是化学及相关专业的必修课。随着社会的发展,物理化学在化学、生命、材料、能源等领域发挥着越来越重要的作用。针对物理化学的课程特点和现代科技发展的需要,本文从教师素养、教学方法、教学理念和实验教学等方面总结了把握研究前沿,提高物理化学教学质量的几点实践和体会。 相似文献
69.
The paper reviews the effects of pigmentation, i.e. type of pigment and pigment volume concentration, on organic coating characteristics, such as curing and film formation, mechanical properties, thermal expansion coefficient, glass transition temperature, stress development, physical ageing and water transport. The main families of pigments used in the fabrication of organic coatings and the effect of nanopigments incorporation in binders are also discussed. 相似文献
70.
Juan Wu Tiejun Hou Maolin Zhang Qijiang Li Junming Wu Jiazhi Li Zequn Deng 《Ceramics International》2013
Yixing Zisha pottery is one of the most representative and influential traditional tea sets in ancient and even contemporary China. Chemical and phase composition, microstructure and performance of Yixing Zisha pottery samples from the late Ming Dynasty to the late Qing Dynasty (1573 A.D.–1911 A.D.) unearthed for the first time in the Shushan Mountain Zisha pottery kiln sites in the western and southern hills of Shushan Mountain, Dingshu Town, Yixing City, China, were systematically analyzed. The chemical composition variations of Yixing Zisha pottery of the above-mentioned periods were studied. Porous structure of Yixing Zisha pottery body was discovered and the relationships among the unique performance of Yixing Zisha pottery, its raw material and the special technological process were discussed. 相似文献