全文获取类型
收费全文 | 11443篇 |
免费 | 887篇 |
国内免费 | 434篇 |
专业分类
电工技术 | 652篇 |
技术理论 | 1篇 |
综合类 | 780篇 |
化学工业 | 1907篇 |
金属工艺 | 871篇 |
机械仪表 | 758篇 |
建筑科学 | 796篇 |
矿业工程 | 263篇 |
能源动力 | 314篇 |
轻工业 | 577篇 |
水利工程 | 207篇 |
石油天然气 | 822篇 |
武器工业 | 105篇 |
无线电 | 1126篇 |
一般工业技术 | 1411篇 |
冶金工业 | 713篇 |
原子能技术 | 115篇 |
自动化技术 | 1346篇 |
出版年
2024年 | 54篇 |
2023年 | 173篇 |
2022年 | 262篇 |
2021年 | 374篇 |
2020年 | 299篇 |
2019年 | 272篇 |
2018年 | 312篇 |
2017年 | 335篇 |
2016年 | 317篇 |
2015年 | 404篇 |
2014年 | 493篇 |
2013年 | 684篇 |
2012年 | 645篇 |
2011年 | 768篇 |
2010年 | 688篇 |
2009年 | 671篇 |
2008年 | 709篇 |
2007年 | 689篇 |
2006年 | 647篇 |
2005年 | 586篇 |
2004年 | 374篇 |
2003年 | 295篇 |
2002年 | 337篇 |
2001年 | 291篇 |
2000年 | 300篇 |
1999年 | 347篇 |
1998年 | 276篇 |
1997年 | 241篇 |
1996年 | 194篇 |
1995年 | 168篇 |
1994年 | 121篇 |
1993年 | 112篇 |
1992年 | 78篇 |
1991年 | 59篇 |
1990年 | 48篇 |
1989年 | 48篇 |
1988年 | 25篇 |
1987年 | 18篇 |
1986年 | 18篇 |
1985年 | 5篇 |
1984年 | 7篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
国内外无机颜料工业的现状及发展趋势 总被引:1,自引:0,他引:1
阐述了国内外无机颜料的生产及需求现状,预测了无机颜料工业的发展趋势、产品发展方向,提出了发展我国无机颜料工业的策略。 相似文献
82.
扼要介绍了某选厂碎磨试验研究的情况.并根据研究结论,提出了该厂技术改造应当采用的流程与设备方案,以提高产品合格粒级产率。 相似文献
83.
本文就十余年来我国在冶金学领域使用国际单位制所遇到的问题,特别是关于热量和压力单位等问题,提出一些不同的意见;期望在冶金领域中使用国际单位更加顺利,又不要影响数据的精确性. 相似文献
85.
The flame‐retardant and smoke‐suppressant properties of inorganic tin compounds such as zinc hydroxystannate (ZHS) and zinc stannate (ZS) were investigated in a comparison with alumina trihydrate, magnesium hydroxide, and Sb2O3 through the limiting oxygen index test and smoke density test. The flame‐retardant mechanisms were studied through the char yield test, SEM, quantitative analysis, thermogravimetry and differential thermal analysis. The thermal degradation in air of flexible PVC treated with the above compounds was studied by thermal analysis from ambient temperature to 800°C. The results showed that tin compounds such as ZHS and ZS could be used as a highly effective flame retardant for flexible PVC, and it appears that the tin compound may exert its action in both the condensed and vapor phases, but mainly in condensed phases as a Lewis acid. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1469–1475, 2005 相似文献
86.
利用ANSYS软件,模拟了振动诱导单螺杆挤出机熔体输送段中非牛顿幂律流体的三维脉动流场,得到了三维脉动流场的瞬时速度分布及螺槽中物料的流动轨迹。结果表明,在脉动流场作用下,非牛顿流体的瞬时速度响应与在驱动壁面上所施加的正弦形式的脉动驱动形式不同,横螺槽方向的环流中心位置受幂律指数影响,且发生周期性改变。振动的引入使得在相同的时间内,物料的流动路程增加,且可增大物料的平均停留时间,有利于改善混合效果。 相似文献
87.
Yang Yu-Xiang Qu Xu-Ping Chen Ya-Ru Jia Xiang-Chen Zhang Jian-Bo Liu Xiang-Nong 《Journal of the American Ceramic Society》2007,90(7):2050-2056
Mesoporous silica materials with ordered hexagonal and parallel-arranged pore channel have been synthesized using cetyl trimethylammonium bromide as a template and Na2 SO4 as counterions. Their ordered mesostructures were characterized by infrared spectroscopy, X-ray diffraction patterns, scanning electron microscopy, transmission electron microscopy, and nitrogen sorption analysis. The effects of Na2 SO4 concentration on variations of morphology, specific surface area, and pore size were discussed; the results show that a high concentration of Na2 SO4 induces the formation of crystal threads with a "tubules-within-tubule" structure, and also leads to mesoporous silica materials with spherical, fabaceous, sheet-like, or prismatic shapes. The results also show that a high concentration of Na2 SO4 can make the pore size decrease, but cannot change pore wall thickness, demonstrating the stability of the hexagonal-shaped pores. 相似文献
88.
The supermolecular structure of photocross-linked polyethylene (XLPE) has been studied by small-angle light scattering (SALS). The data show that the spherulitic structure of XLPE gradually deteriorates with increasing degree of cross-linking and increasing irradiation temperature from well-developed spherulites to rodlike aggregates and disordered lamellar structures. A photocross-linked sample of PE has lower crystallinity, smaller crystallites, and smaller spherulites than does the original sample. At high degrees of cross-linking, the SALS patterns show little or no spherulitic structure. Results with photocross-linked polyethylene demonstrate that the overall effect of cross-linking on the morphological structure is similar to that of an increase in molecular weight of the polymer. © 1993 John Wiley & Sons, Inc. 相似文献
89.
Photoinitiated crosslinking of EVA in the presence of benzophenone (BP) as photoinitiator and triallyl isocyanurate (TAIC) as crosslinker and characterization of the related properties have been studied by gel determination, heat extension, DSC, DMTA, TGA, and mechanical measurements. The photoinitiated crosslinking efficiency of the EVA‐BP‐TAIC system and various factors affecting the crosslinking process, such as photoinitiator and crosslinker and their concentrations, irradiation temperature, and irradiation atmosphere were studied in detail and optimized by comparison of gel contents. The results show that the EVA samples with a thickness of 1 mm are readily crosslinked to a gel content of above 80% with 5 s UV‐irradiation under optimum conditions. The data from the heat extension and DSC show that the crosslinking density of photocrosslinked EVA increase and their crystallinities decrease with increasing the UV‐irradiation time. At the same time, photocrosslinking of EVA leads to a lowering of the melt temperature and a decrease of heat of fusion. The DMTA results show that photocrosslinking increases the amorphous phase and storage modulus of the crosslinked EVA, but does not change the glass transition temperature. The data from TGA and mechanical tests give evidence that the thermal stability and mechanical properties of photocrosslinked EVA samples are much better than those of the uncrosslinked EVA. POLYM. ENG. SCI., 47:1761–1767, 2007. © 2007 Society of Plastics Engineers 相似文献
90.
The effect of preparation method on MnO
x
–CeO2 mixed oxide catalysts for methane combustion at low temperature was investigated by means of BET, XRD, XPS, H2-TPR techniques and methane oxidation reaction. The catalysts were prepared by the conventional coprecipitation, plasma and
modified coprecipitation methods, respectively. It was found that the catalyst prepared by modified coprecipitation was the
most active, over which methane conversion reached 90% at a temperature as low as 390 °C. The XRD results showed the preparation
methods had no effect on the solid solution structure of MnO
x
–CeO2 catalysts. More Mn4+ and richer lattice oxygen were found on the surface of the modified coprecipitation prepared catalyst with the help of XPS
analysis, and its reduction and BET surface area were remarkably promoted. These factors could be responsible for its higher
activity for methane combustion at low temperature. 相似文献