全文获取类型
收费全文 | 9581篇 |
免费 | 1561篇 |
国内免费 | 576篇 |
专业分类
电工技术 | 376篇 |
技术理论 | 3篇 |
综合类 | 1525篇 |
化学工业 | 2328篇 |
金属工艺 | 265篇 |
机械仪表 | 498篇 |
建筑科学 | 934篇 |
矿业工程 | 807篇 |
能源动力 | 458篇 |
轻工业 | 357篇 |
水利工程 | 449篇 |
石油天然气 | 520篇 |
武器工业 | 297篇 |
无线电 | 375篇 |
一般工业技术 | 858篇 |
冶金工业 | 382篇 |
原子能技术 | 133篇 |
自动化技术 | 1153篇 |
出版年
2024年 | 20篇 |
2023年 | 96篇 |
2022年 | 276篇 |
2021年 | 359篇 |
2020年 | 332篇 |
2019年 | 282篇 |
2018年 | 256篇 |
2017年 | 328篇 |
2016年 | 385篇 |
2015年 | 404篇 |
2014年 | 659篇 |
2013年 | 663篇 |
2012年 | 739篇 |
2011年 | 750篇 |
2010年 | 622篇 |
2009年 | 618篇 |
2008年 | 522篇 |
2007年 | 610篇 |
2006年 | 564篇 |
2005年 | 509篇 |
2004年 | 456篇 |
2003年 | 333篇 |
2002年 | 322篇 |
2001年 | 253篇 |
2000年 | 237篇 |
1999年 | 212篇 |
1998年 | 147篇 |
1997年 | 143篇 |
1996年 | 95篇 |
1995年 | 105篇 |
1994年 | 80篇 |
1993年 | 46篇 |
1992年 | 50篇 |
1991年 | 41篇 |
1990年 | 44篇 |
1989年 | 27篇 |
1988年 | 27篇 |
1987年 | 14篇 |
1986年 | 15篇 |
1985年 | 7篇 |
1984年 | 10篇 |
1983年 | 13篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1979年 | 3篇 |
1977年 | 4篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1966年 | 4篇 |
1963年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
面对80亿元人民币投资我国子午胎产业的热潮,冷静解剖轮胎产业和市场,按照经济结构分析企业发展趋势,预测子午胎企业2003年市场需求和近几年发展总趋势。提出构筑子午胎企业竞争优势的战略大框架,建议组建国家级联合舰队,提升我国子午胎行业的国际竞争力,规避市场风险。 相似文献
102.
Ethylene–propylene–diene terpolymer (EPDM) was modified by bromination reaction. Blending the resulting brominated EPDM with natural rubber (STR5L) and blending the unmodified EPDM with STR5L at various compositions were carried out. The rheological properties of the blends were investigated using a capillary extrusion. Shear flow curves of the pure rubbers and their blends illustrated the pseudoplastic property as shear thinning behavior with a power law index n < 1. True shear viscosity of all blends showed the negative deviation in relation to their additive values. Rheological behavior and two Tg's found from the DSC thermograms at all blend compositions indicated blend incompatibility for both sets of blends. The incompatibility of the vulcanized blends was also found by measuring the spin–spin relaxation time T2 by pulsed NMR. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 837–847, 2003 相似文献
103.
P.L. Lin P.Y. Huang P.W. Huang H.C. Hsu C.C. Chen 《Computer methods and programs in biomedicine》2014
Teeth segmentation for periapical raidographs is one of the most critical tasks for effective periapical lesion or periodontitis detection, as both types of anomalies usually occur around tooth boundaries and dental radiographs are often subject to noise, low contrast, and uneven illumination. In this paper, we propose an effective scheme to segment each tooth in periapical radiographs. The method consists of four stages: image enhancement using adaptive power law transformation, local singularity analysis using Hölder exponent, tooth recognition using Otsu's thresholding and connected component analysis, and tooth delineation using snake boundary tracking and morphological operations. Experimental results of 28 periapical radiographs containing 106 teeth in total and 75 useful for dental examination demonstrate that 105 teeth are successfully isolated and segmented, and the overall mean segmentation accuracy of all 75 useful teeth in terms of (TP, FP) is (0.8959, 0.0093) with standard deviation (0.0737, 0.0096), respectively. 相似文献
104.
Fei Yan Josef Kittler David Windridge William Christmas Krystian Mikolajczyk Stephen Cox Qiang Huang 《Image and vision computing》2014
Fully automatic annotation of tennis game using broadcast video is a task with a great potential but with enormous challenges. In this paper we describe our approach to this task, which integrates computer vision, machine listening, and machine learning. At the low level processing, we improve upon our previously proposed state-of-the-art tennis ball tracking algorithm and employ audio signal processing techniques to detect key events and construct features for classifying the events. At high level analysis, we model event classification as a sequence labelling problem, and investigate four machine learning techniques using simulated event sequences. Finally, we evaluate our proposed approach on three real world tennis games, and discuss the interplay between audio, vision and learning. To the best of our knowledge, our system is the only one that can annotate tennis game at such a detailed level. 相似文献
105.
106.
107.
介绍软PLC技术的原理和在钢丝帘布小角度裁断机上的应用.小角度裁断机上的软PLC系统硬件由工业PC和远程分布式I/O系统组成,采用TwinCAT System软件(由系统说明、系统控制、PLC控制和系统管理器4部分组成),安装在Windows操作系统上.与传统PLC系统相比,软PLC系统方便和简化了小角度裁断机控制系统的设计和施工,减少了设计、安装、测试、维护和维修费用. 相似文献
108.
应用Monsanto加工性能试验机(MPT)对胎面胶进行压出流变试验。在实验条件下,考察试样熔体的流动特性及其影响因素,并作初步的分析和讨论。实验发现,试样的流动曲线可近似用指数方程描述;而熔体粘度对温度的依赖性则大体上符合Arrhenius方程。 相似文献
109.
110.
Pramod Kandanarachchi Andrew Guo Dmytro Demydov Zoran Petrovic 《Journal of the American Oil Chemists' Society》2002,79(12):1221-1225
The kinetics and mechanism of the hydroformylation of soybean oil by homogeneous ligand-modified rhodium catalysts were investigated
at 70–130°C and 4000–11,000 kPa. The effects of reaction rates on systematic variations in reaction parameters were evaluated
in order to develop an industrial process to convert vegetable oils to polyaldehydes. The activation energies in the presence
of triphenylphosphine (Ph3P) (61.1±0.8 kJ/mol) (mean±SD) and triphenyl phosphite [(PhO)3P] (77.4±5.0 kJ/mol) were determined. The catalyst was deactivated at temperatures higher than 100°C. An evaluation of the
effects of the reaction parameters on initial rates yielded the rate laws for Ph3P {rate=k [olefin][Rh(CO)2Acac]1.1 [Ph3P]−0.5 (pH2+pCO)1.4, where Rh(CO)2Acac is (acetylacetonato)dicarbonylrhodium (I)} and (PhO)3P {rate=[olefin] [Rh(CO)2Acac]1.2 [(PhO)3P]−0.8 (pH2+pCO)0.9 at total pressures lower than 7000 kPa, and rate =[olefin] [Rh(CO)2Acac]1.2 [(PhO)3P]−0.8(pH2+pCO)1.7 at total pressures higher than 7000 kPa}. 相似文献