全文获取类型
收费全文 | 11447篇 |
免费 | 1606篇 |
国内免费 | 715篇 |
专业分类
电工技术 | 220篇 |
综合类 | 697篇 |
化学工业 | 2318篇 |
金属工艺 | 597篇 |
机械仪表 | 1976篇 |
建筑科学 | 392篇 |
矿业工程 | 192篇 |
能源动力 | 126篇 |
轻工业 | 798篇 |
水利工程 | 111篇 |
石油天然气 | 221篇 |
武器工业 | 118篇 |
无线电 | 1919篇 |
一般工业技术 | 1540篇 |
冶金工业 | 205篇 |
原子能技术 | 113篇 |
自动化技术 | 2225篇 |
出版年
2024年 | 50篇 |
2023年 | 228篇 |
2022年 | 357篇 |
2021年 | 412篇 |
2020年 | 433篇 |
2019年 | 437篇 |
2018年 | 361篇 |
2017年 | 482篇 |
2016年 | 536篇 |
2015年 | 539篇 |
2014年 | 695篇 |
2013年 | 763篇 |
2012年 | 760篇 |
2011年 | 758篇 |
2010年 | 556篇 |
2009年 | 559篇 |
2008年 | 598篇 |
2007年 | 603篇 |
2006年 | 606篇 |
2005年 | 526篇 |
2004年 | 470篇 |
2003年 | 464篇 |
2002年 | 374篇 |
2001年 | 297篇 |
2000年 | 258篇 |
1999年 | 263篇 |
1998年 | 215篇 |
1997年 | 190篇 |
1996年 | 155篇 |
1995年 | 113篇 |
1994年 | 114篇 |
1993年 | 105篇 |
1992年 | 69篇 |
1991年 | 71篇 |
1990年 | 52篇 |
1989年 | 33篇 |
1988年 | 48篇 |
1987年 | 22篇 |
1986年 | 33篇 |
1985年 | 40篇 |
1984年 | 28篇 |
1983年 | 35篇 |
1982年 | 21篇 |
1981年 | 13篇 |
1980年 | 4篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1964年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
采用高速摄像与ESPI技术相结合,将运动中的被测物位移随时间变化的状态以序列图像的形式实时记录,并运用图像处理技术,成功地实现了ESPI动态测量。测量了悬臂梁的自由振动过程,获得了悬臂梁的振动周期、振动频率和阻尼系数等动态特性,实验结果与理论计算值相吻合。 相似文献
62.
杨洪梅 《陶瓷研究与职业教育》2006,4(4):29-30
形象思维足语文教学内容的一个重要组成部分,是语言表达的基础.语文课应该重视对学生形象思维的培养与训练. 相似文献
63.
Peichun Li Amar Zerroukhi Jianding Chen Yvan Chalamet Thomas Jeanmaire Zhean Xia 《应用聚合物科学杂志》2008,110(6):3990-3998
Chemical shrinkage was used for the in situ measurement of the progressing chemical stabilization reactions and the influence of ozone during the stabilization of polyacrylonitrile. A method for evaluating the activation energy through the sensitivity temperature is presented. The calculated results show that the activation energies were 161.57 kJ/mol in air and 181.23 kJ/mol in ozone-enriched air. Therefore, the chemical reactions were postponed during stabilization in ozone-enriched air. Ozone seemed to act in three ways: first, ozone promoted the formation of the serious skin–core structure. Second, ozone accelerated the chemical reactions and shortened the stabilization time at lower heating rates. Third, ozone postponed the chemical reactions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008 相似文献
64.
Changes in thermomechanical behavior with structural relaxation taking place in epoxy glasses were studied. Differential scanning calorimetry measurements and thermostimulated strain recovery tests were performed for specimens deformed and then aged under fixed strain. In the course of heating, the specimens started to absorb thermal energy, whereas plastic strain was still stable. At higher temperatures, plastic strain started recovery, which was accompanied by exothermic behavior of the specimen. With an increase in the aging duration, the endothermic peak signified and moved to a higher temperature. These results indicated that the longer the aging duration was, the harder the plastic strain and strain energy were frozen in the glassy structure. This freeze‐strain phenomenon was observed for crosslinked epoxy glass, as well as polymeric glasses with linear molecular structures, aged under strain. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
65.
66.
67.
68.
Haruo Mimura Ryusei Sato Yu Sasaki Yuichi Furuyama Akira Taniike Kazutoshi Yoshida Akira Kitamura 《International journal of molecular sciences》2008,9(10):1989-2002
Tributyltin (TBT) released into seawater from ship hulls is a stable marine pollutant and obviously remains in marine environments. We isolated a TBT resistant marine Pseudoalteromonas sp. TBT1 from sediment of a ship’s ballast water. The isolate (109.3 ± 0.2 colony-forming units mL−1) adsorbed TBT in proportion to the concentrations of TBTCl externally added up to 3 mM, where the number of TBT adsorbed by a single cell was estimated to be 108.2. The value was reduced to about one-fifth when the lysozyme-treated cells were used. The surface of ethanol treated cells became rough, but the capacity of TBT adsorption was the same as that for native cells. These results indicate that the function of the cell surface, rather than that structure, plays an important role to the adsorption of TBT. The adsorption state of TBT seems to be multi-layer when the number of more than 106.8 TBT molecules is adsorbed by a single cell. 相似文献
69.
Current understanding of the mechanisms involved in osseointegration following implantation of a biomaterial has led to adhesion quantification being implemented as an assay of cytocompatibility. Such measurement can be hindered by intra-sample variation owing to morphological changes associated with the cell cycle. Here we report on a new scanning electron microscopical method for the simultaneous immunogold labelling of cellular focal adhesions and S-phase nuclei identified by BrdU incorporation. Prior to labelling, cellular membranes are removed by tritonization and antigens of non-interest blocked by serum incubation. Adhesion plaque–associated vinculin and S-phase nuclei were both separately labelled with a 1.4 nm gold colloid and visualized by subsequent colloid enhancement via silver deposition. This study is specifically concerned with the effects microgroove topographies have on adhesion formation in S-phase osteoblasts. By combining backscattered electron (BSE) imaging with secondary electron (SE) imaging it was possible to visualize S-phase nuclei and the immunogold-labelled adhesion sites in one energy 'plane' and the underlying nanotopography in another. Osteoblast adhesion to these nanotopographies was ascertained by quantification of adhesion complex formation. 相似文献
70.
Legendre orthogonal moments have been widely used in the field of image analysis. Because their computation by a direct method is very time expensive, recent efforts have been devoted to the reduction of computational complexity. Nevertheless, the existing algorithms are mainly focused on binary images. We propose here a new fast method for computing the Legendre moments, which is not only suitable for binary images but also for grey level images. We first establish a recurrence formula of one-dimensional (1D) Legendre moments by using the recursive property of Legendre polynomials. As a result, the 1D Legendre moments of order p, Lp=Lp(0), can be expressed as a linear combination of Lp-1(1) and Lp-2(0). Based on this relationship, the 1D Legendre moments Lp(0) can thus be obtained from the arrays of L1(a) and L0(a), where a is an integer number less than p. To further decrease the computation complexity, an algorithm, in which no multiplication is required, is used to compute these quantities. The method is then extended to the calculation of the two-dimensional Legendre moments Lpq. We show that the proposed method is more efficient than the direct method. 相似文献