全文获取类型
收费全文 | 3789篇 |
免费 | 261篇 |
国内免费 | 107篇 |
专业分类
电工技术 | 148篇 |
综合类 | 298篇 |
化学工业 | 217篇 |
金属工艺 | 403篇 |
机械仪表 | 331篇 |
建筑科学 | 727篇 |
矿业工程 | 92篇 |
能源动力 | 163篇 |
轻工业 | 221篇 |
水利工程 | 82篇 |
石油天然气 | 29篇 |
武器工业 | 26篇 |
无线电 | 453篇 |
一般工业技术 | 545篇 |
冶金工业 | 85篇 |
原子能技术 | 24篇 |
自动化技术 | 313篇 |
出版年
2024年 | 7篇 |
2023年 | 22篇 |
2022年 | 72篇 |
2021年 | 111篇 |
2020年 | 91篇 |
2019年 | 74篇 |
2018年 | 72篇 |
2017年 | 112篇 |
2016年 | 123篇 |
2015年 | 141篇 |
2014年 | 247篇 |
2013年 | 201篇 |
2012年 | 272篇 |
2011年 | 307篇 |
2010年 | 251篇 |
2009年 | 237篇 |
2008年 | 214篇 |
2007年 | 278篇 |
2006年 | 237篇 |
2005年 | 196篇 |
2004年 | 183篇 |
2003年 | 130篇 |
2002年 | 118篇 |
2001年 | 99篇 |
2000年 | 85篇 |
1999年 | 74篇 |
1998年 | 51篇 |
1997年 | 37篇 |
1996年 | 25篇 |
1995年 | 27篇 |
1994年 | 11篇 |
1993年 | 13篇 |
1992年 | 10篇 |
1991年 | 7篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1958年 | 1篇 |
1957年 | 2篇 |
1956年 | 1篇 |
排序方式: 共有4157条查询结果,搜索用时 15 毫秒
51.
Abstract— Bit‐partitioned and conventional shifts, as well as type transformations of multimedia data, are frequently used for display image‐processing systems. A data manipulation unit with fault‐recovery capability based on redundancies is proposed for system‐on‐panel with low processing technology yield. Utilizing data manipulations that are similar to normal shift operation, a proposed data‐manipulation unit is designed with a few additional paths added to the existing barrel shifter. The design methodologies are verified with FPGA and the performance is evaluated in terms of the advantages. 相似文献
52.
G. Oversluize S. De Zwart S. van Heusden T. Dekker 《Journal of the Society for Information Display》2000,8(3):197-201
Abstract— The dependence of PDP luminance and efficacy on the input power was investigated for several Xe‐Ne gas mixtures. The input power was varied in two ways: namely, by changing the dielectric‐layer capacitance (thickness) and by changing the sustain voltage. A distinctly different behavior was found; for increasing capacitance the efficacy decreases markedly, whereas for increasing sustain voltage the efficacy increases. A design window comprising the combination of a high Xe concentration and a high sustain voltage was suggested. In this window, a high luminance and a high efficacy are concurrent. A 4‐in. test panel with 10% Xe in Ne has been realized showing a white luminance of 2040 cd/m2 and an efficacy of 2.3 lm/W for continuous sustaining at 50 kHz with a sustain voltage of 225 V. 相似文献
53.
张建平 《中国农村水电及电气化》2013,(7):8-11
混凝土面板堆石坝是由防渗系统和堆石体构成的,在我国科学技术不断提高的情况下,面板堆石坝得到了空前的发展,常用于水利建设工程中,经调查发现,有很多的高坝面板结构出现了裂缝。基于此本文对水利工程混凝土面板堆石坝的设计措施进行了探讨。 相似文献
54.
为了使新型碳晶板地热电采暖系统能在民用采暖领域更广泛地应用,更好地发挥其清洁、调控方便等优点,通过实验测试和模拟研究相结合的方法,测试和模拟分析了采用碳晶电热板系统的标准实验小室的动态加热过程;并利用经实验验证的模拟模型,对北京市某房间内碳晶电热板系统24 h温控调节过程进行数值模拟,提出了合理的温控控制因素和调节方案,确定了温控装置的温度限值以实现温控过程,为该电采暖系统的节能运行,提供了技术支撑. 相似文献
55.
尾板对重型载货汽车尾部流场的影响 总被引:1,自引:0,他引:1
为了降低风的阻力,对某牵引式重型载货汽车加装了4种不同形式和尺寸的尾板。并采用数值仿真的方法分析了尾板对流场的影响,探索了风阻产生机理和降低原因。仿真工况模拟正常车辆行驶速度25m/s,未考虑侧风影响。计算结果表明:安装4种尾板后风阻系数均有降低,降幅最大为2.8%,获得了较满意的降阻效果。对比分析了4种方案的整车气动阻力系数、流速分布及总压为零等值面的计算结果。研究发现:尾板对车身周围气流的影响集中在货箱尾部,改变了尾流中原有的环形漩涡结构,从而降低了风阻。 相似文献
56.
Mahdi Ghasemi-Varnamkhasti Seyed Saeid MohtasebiMaria Luz Rodriguez-Mendez Jesus LozanoSeyed Hadi Razavi Hojat AhmadiConstantin Apetrei 《Expert systems with applications》2012,39(4):4315-4327
Sensory evaluation is the application of knowledge and skills derived from several different scientific and technical disciplines, physiology, chemistry, mathematics and statistics, human behavior, and knowledge about product preparation practices. This research was aimed to evaluate aftertaste sensory attributes of commercial non-alcoholic beer brands (P1, P2, P3, P4, P5, P6, P7) by several chemometric tools. These attributes were bitter, sour, sweet, fruity, liquorice, artificial, body, intensity and duration. The results showed that the data are in a good consistency. Therefore, the brands were statistically classified in several categories. Linear techniques as Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA) were performed over the data that revealed all types of beer are well separated except a partial overlapping between zones corresponding to P4, P6 and P7. In this research, for the confirmation of the groups observed in PCA and in order to calculate the errors in calibration and in validation, PLS-DA technique was used. Based on the quantitative data of PLS-DA, the classification accuracy values were ranked within 49-86%. Moreover, it was found that the classification accuracy of LDA was much better than PCA. It shows that this trained sensory panel can discriminate among the samples except an overlapping between two types of beer. Also, two types of artificial networks were used: Probabilistic Neural Networks (PNN) with Radial Basis Functions (RBF) and FeedForward Networks with Back Propagation (BP) learning method. The highest classification success rate (correct predicted number over total number of measurements) of about 97% was obtained for RBF followed by 94% for BP. The results obtained in this study could be used as a reference for electronic nose and electronic tongue in beer quality control. 相似文献
57.
由纸蜂窝和玻璃布面板制成的蜂窝夹层板具有质轻、比强度高、隔音、隔热和防潮等特点,是一种极有前途的新型建筑材料,研制了一种具有成本低、污染小、阻燃等特点,可满足建筑用蜂窝板的制造工艺和使用性能要求的胶粘剂。 相似文献
58.
Jeong-Ryeol Kim Geun-Kyu Choi Dong Kyun Yim Jong-Sung Park Kug Sun Hong 《Journal of Electroceramics》2006,17(1):65-69
Glasses in the ZnO-B2O3-MO3(M = W, Mo) ternary were examined as potential replacements to PbO-B2O3-SiO2-ZnO glass frits with the low firing temperature (500–600∘C) for the dielectric layer of a plasma display panels (PDPs). Glasses were melted in air at 950–1150∘C in a narrow region of the ternary using standard reagent grade materials. The glasses were evaluated for glass transition
temperature (T
g
), softening temperature (T
d
), the coefficient of thermal expansion (CTE), dielectric constant (ε
r
), and optical property. The glass transition temperature of the glasses varied between 470 and 560∘C. The coefficient of thermal expansion and the dielectric constant of the glasses were in the range of 5–8 × 10− 6/∘C and 8–10, respectively. The addition of MO3to ZnO-B2O3binary could induce the expansion of glass forming region, the reduction of T
g
and the increase in the CTE and the dielectric constant of the glasses. Also, the effect of the addition of MO3to ZnO-B2O3binary on the transmittance in the visible-light region (350–700 nm) was investigated. 相似文献
59.
60.
黄险峰 《哈尔滨建筑大学学报》2003,(10)
根据工字型建筑构件的构造特点,应用统计能量分析理论,建立工字型构件的隔声计算模型。通过求解能量传递与平衡方程,计算各子系统的损耗系数和子系统之间的耦合损耗系数,得出构件两边的声压级差。与隔声实验和质量定律计算的结果相比,应用统计能量分析方法计算的结果与实验符合得很好,具有较高的精确性。此方法可以进一步解决构造复杂墙体的隔声问题,通过改进墙体构造,提高隔声性能。 相似文献