全文获取类型
收费全文 | 1404篇 |
免费 | 8篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 5篇 |
化学工业 | 61篇 |
金属工艺 | 6篇 |
机械仪表 | 6篇 |
建筑科学 | 7篇 |
矿业工程 | 2篇 |
能源动力 | 11篇 |
轻工业 | 27篇 |
水利工程 | 1篇 |
石油天然气 | 2篇 |
无线电 | 12篇 |
一般工业技术 | 24篇 |
冶金工业 | 1222篇 |
原子能技术 | 2篇 |
自动化技术 | 25篇 |
出版年
2023年 | 3篇 |
2022年 | 2篇 |
2021年 | 6篇 |
2020年 | 6篇 |
2019年 | 5篇 |
2018年 | 4篇 |
2017年 | 11篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 7篇 |
2013年 | 22篇 |
2012年 | 9篇 |
2011年 | 15篇 |
2010年 | 9篇 |
2009年 | 8篇 |
2008年 | 6篇 |
2007年 | 7篇 |
2006年 | 9篇 |
2005年 | 11篇 |
2004年 | 10篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 5篇 |
1999年 | 46篇 |
1998年 | 385篇 |
1997年 | 219篇 |
1996年 | 150篇 |
1995年 | 72篇 |
1994年 | 62篇 |
1993年 | 72篇 |
1992年 | 14篇 |
1991年 | 13篇 |
1990年 | 14篇 |
1989年 | 18篇 |
1988年 | 25篇 |
1987年 | 16篇 |
1986年 | 9篇 |
1985年 | 16篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 7篇 |
1980年 | 9篇 |
1978年 | 2篇 |
1977年 | 18篇 |
1976年 | 58篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1967年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1413条查询结果,搜索用时 15 毫秒
91.
Maria Virginia Gelfuso Juan Oswaldo Montoya Uribe Daniel Thomazini 《International Journal of Applied Ceramic Technology》2019,16(2):868-882
The influence of the CuO–TiO2 phase (CT) on dielectric properties of the CCTO ceramic was investigated. CaCuXTiYO12 (CCXTYO) powders were prepared based on the coprecipitated method, where 2.70 ≤ x ≤ 3.30 and 3.25 ≤ y ≤ 4.75. XRD patterns confirmed the presence of CCTO and also the secondary phases as CuO, TiO2, and CaTiO3 for each sample and aided in its quantification. Scanning Electron Microscopy (SEM) shows secondary phases evolution in the grain boundaries, and its influence on size and morphology of the grains. Impedance spectroscopy measurements showed that the ceramics with lower amount of CuO and TiO2 phases (CT/deficient ceramics) exhibited the highest ε′ values (2.1 × 104 at 1 kHz for CC2.9T3.75O ceramic). Also, CT/deficient ceramics showed lower tanδ values (0.090 at 1 kHz for CC2.9T3.75O ceramic) than ceramics prepared with excessive CuO–TiO2 phase (0.241 at 1 kHz for CC3.1T4.25O ceramics). The deficiency of CuO and TiO2 phases associated with high percentage of CCTO and CaTiO3 phases resulted in ceramics with the higher ε′ values. 相似文献
92.
93.
MA Crosby C Miller T Alon KL Watson CP Verrijzer R Goldman-Levi NB Zak 《Canadian Metallurgical Quarterly》1999,19(2):1159-1170
The genes of the trithorax group (trxG) in Drosophila melanogaster are required to maintain the pattern of homeotic gene expression that is established early in embryogenesis by the transient expression of the segmentation genes. The precise role of each of the diverse trxG members and the functional relationships among them are not well understood. Here, we report on the isolation of the trxG gene moira (mor) and its molecular characterization. mor encodes a fruit fly homolog of the human and yeast chromatin-remodeling factors BAF170, BAF155, and SWI3. mor is widely expressed throughout development, and its 170-kDa protein product is present in many embryonic tissues. In vitro, MOR can bind to itself and it interacts with Brahma (BRM), an SWI2-SNF2 homolog, with which it is associated in embryonic nuclear extracts. The leucine zipper motif of MOR is likely to participate in self-oligomerization; the equally conserved SANT domain, for which no function is known, may be required for optimal binding to BRM. MOR thus joins BRM and Snf5-related 1 (SNR1), two known Drosophila SWI-SNF subunits that act as positive regulators of the homeotic genes. These observations provide a molecular explanation for the phenotypic and genetic relationships among several of the trxG genes by suggesting that they encode evolutionarily conserved components of a chromatin-remodeling complex. 相似文献
94.
J.‐L. Molina‐Cano A. Rubi E. Igartua P. Gracia J.‐L. Montoya 《Journal of the Institute of Brewing》2000,106(2):111-116
Malt extract yield (EXT) and barley protein content (BPROT) data from 346 EBC trials located across all the EBC countries, and composed of many different varieties, from the years 1980, 1982 to 1990, inclusive, and 1993 to 1995, thus covering 13 seasons, were used to detect regional trends affecting the negative correlation between these two variables. Quadratic curves were fitted to data from each European region (North, Central, West and South), all of which showed very high coefficients of determination (r2). A common trend in all regions, and also in the overall European analysis, was of EXT decreasing when BPROT increased, although the extent of decrease varied among the regions. Two different geographical patterns of variation in EXT with changes in BPROT have been observed, on the one hand those of the Iberian Peninsula and West region, and on the other, those of the North and Central regions. In the first case, the rate of decrease in EXT was almost constant across the full range of variation of BPROT, whereas, in the second case, the decrease in EXT grew progressively with increases in BPROT. Therefore, although “Bishop's law” on EXT decrease with BPROT increase holds true as a general statement, it would be necessary to take climatic differences into account when estimating EXT values from BPROT data. 相似文献
95.
96.
Hartmann and Hasher (1991) used a garden-path task in which younger and older adults generated the final word for each of a series of high-cloze sentences. Under instructions to remember the final word, the experiment included critical sentences for which the generated word was replaced by a new, to-be-remembered target. Using an implicit priming task, the first experiment replicated a basic finding: Younger adults showed priming only for the target words, whereas older adults showed priming for both the generated and target words. Two experiments explored the boundary conditions. One showed that an additional sentence that interpreted the new target word enabled older adults to narrow access to only the target word. The provision of additional time following the introduction of the new target word did not. Specific information, not more time, is required for inefficient inhibitory mechanisms to clear the recent past from memory. 相似文献
97.
A method of improving the bondability of cured RTV silicone is described. The method is based on the use of excited oxygen plasma in a glow discharge chamber. Surface characteristics and bond strength, before and after treatment, are reported. Significance of the results in the light of present adhesion theory is also discussed. 相似文献
98.
G Ginther RM Edelstein CP Forsyth K Gamarnik AE Kreymer RJ Lipton JM McQuade DM Potter JS Russ L Spiegel DE Johnson D Buchholz LM Cremaldi SW Delchamps HS Mao JL Rosen W Sakumoto RA Schluter SB Sontz C Winter JM Bishop NN Biswas NM Cason L Dauwe J Godfrey VP Kenney P Mooney R Pemper E Rojek RC Ruchti M Sarmiento WD Shephard 《Canadian Metallurgical Quarterly》1987,35(5):1541-1552
99.
100.