全文获取类型
收费全文 | 1005篇 |
免费 | 46篇 |
国内免费 | 114篇 |
专业分类
电工技术 | 16篇 |
综合类 | 97篇 |
化学工业 | 254篇 |
金属工艺 | 70篇 |
机械仪表 | 5篇 |
建筑科学 | 7篇 |
矿业工程 | 9篇 |
能源动力 | 18篇 |
轻工业 | 30篇 |
水利工程 | 2篇 |
石油天然气 | 18篇 |
武器工业 | 5篇 |
无线电 | 68篇 |
一般工业技术 | 205篇 |
冶金工业 | 192篇 |
原子能技术 | 153篇 |
自动化技术 | 16篇 |
出版年
2023年 | 11篇 |
2022年 | 7篇 |
2021年 | 19篇 |
2020年 | 21篇 |
2019年 | 13篇 |
2018年 | 20篇 |
2017年 | 22篇 |
2016年 | 27篇 |
2015年 | 18篇 |
2014年 | 43篇 |
2013年 | 79篇 |
2012年 | 95篇 |
2011年 | 90篇 |
2010年 | 101篇 |
2009年 | 93篇 |
2008年 | 59篇 |
2007年 | 86篇 |
2006年 | 87篇 |
2005年 | 71篇 |
2004年 | 28篇 |
2003年 | 24篇 |
2002年 | 24篇 |
2001年 | 25篇 |
2000年 | 14篇 |
1999年 | 14篇 |
1998年 | 9篇 |
1997年 | 11篇 |
1996年 | 7篇 |
1995年 | 11篇 |
1994年 | 7篇 |
1993年 | 10篇 |
1992年 | 4篇 |
1991年 | 9篇 |
1990年 | 1篇 |
1987年 | 1篇 |
1983年 | 2篇 |
1980年 | 2篇 |
排序方式: 共有1165条查询结果,搜索用时 15 毫秒
11.
Eu3 ions were incorporated in sol and gel by a sol-gel processing using 3-glycidoxypropyltrimethoxysilane(CH2OCHCH2O(CH2)3Si(OCH3)3, GPTMS) and ethyl silicate (TEOS) as precursors. The basic chemical-physical properties such as DTA curve, FF-IR spectra and specific surface area were recorded. The characteristics of their optical spectra were measured and investigated. The results indicate that the emission intensity of Eu3 ion in ormocer is much higher and the global line width is wider than those in SiO2 gel. The relationship between the composition and structure of gels and the fluorescence intensity and width were discussed. The obtained ormocer shows good mechanical strength, which can be cut and polished in machine without broken. 相似文献
12.
Bright red luminescent Eu3+ doped polyvinyl alcohol (PVA) films were made by solution casting technique. The emission performance of these films was studied from the measurement of excitation, emission, and lifetimes. On irradiation with an UV source, the doped films emitted bright red light. Such luminescent polymer films are expected to find potential applications as new optical materials. Emission process in the system was explained by an energy level scheme. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3273–3276, 2006 相似文献
13.
14.
A spherical acoustic resonator was developed for measuring sound velocities in the gaseous phase and ideal-gas specific heats for new refrigerants. The radius of the spherical resonator, being about 5 cm, was determined by measuring sound velocities in gaseous argon at temperatures from 273 to 348 K and pressures up to 240 kPa. The measurements of 23 sound velocities in gaseous HFC-134a (1,1,1,2-tetrafluoroethane) at temperatures of 273 and 298 K and pressures from 10 to 250 kPa agree well with the measurements of Goodwin and Moldover. In addition, 92 sound velocities in gaseous HFC-152a (1,1-difluoroethane) with an accuracy of ±0.01% were measured at temperatures from 273 to 348 K and pressures up to 250 kPa. The ideal-gas specific heats as well as the second acoustic virial coefficients have been obtained for both these important alternative refrigerants. The second virial coefficients for HFC-152a derived from the present sound velocity measurements agree extremely well with the reported second virial coefficient values obtained with a Burnett apparatus.Paper dedicated to Professor Joseph Kestin. 相似文献
15.
Experimental vapor pressures andP--T data of an important alternative refrigerant, 1, 1-difluoroethane (HFC-152a), have been measured by means of a constant-volume method coupled with expansion procedures. SixtyP--T data were measured along eight isochores in a range of temperaturesT from 330 to 440 K, at pressuresP from 1.6 to 9.3 MPa, and at densities from 51 to 811 kg·m–3. Forty-six vapor pressures were also measured at temperatures from 320 K to the critical temperature. The uncertainties of the temperature and pressure measurements are within ±7mK and ±2kPa, respectively, while the uncertainty of the density values is within ±0.1%. The purity of the sample used is 99.9 wt%. On the basis of the measurements along each isochore, five saturation points were determined and the critical pressure was determined by correlating the vapor-pressure measurements. The second and third virial coefficients for temperatures from 360 to 440 K have also been determined. 相似文献
16.
萃取预分离法分离富铕中钇矿新工艺 总被引:2,自引:0,他引:2
采用一种新的串级萃取方式--萃取预分离法分离富铕中钇矿的新工艺.原料首先流入十几的三出口预先粗分离工艺,其萃余液La~Gd(TbDy)直接流入Nd/Sm工艺;中间出口流入(Gd)Tb~HoY(Er)Gd~Dy/Ho~LuY细分离工艺;出口负载有机相(Ho)Er~LuY流入Gd~Dy/Ho~LuY的洗涤段.结果表明,新工艺的粗分离工艺将占原料约70%的La~Gd(TbDy)预分离掉,使流入Gd~Dy/Ho~LuY工艺的稀土量减少约70%;由于Gd~Dy/Ho~LuY分组的萃余液GdTbDy含Ho2O3小于0.03%,省去原工艺的GdTbDy/HoY分离;新工艺的处理能力提高30%,酸碱消耗减少20%以上,贵重稀土元素Eu和Tb的存槽量大大减少. 相似文献
17.
18.
聚乙烯转光棚膜的加工及应用研究 总被引:8,自引:3,他引:8
本文对聚乙烯转光棚膜的加工和光转换剂的作用、配比关系及物理性能进行了讨论。 相似文献
19.
综合利用岩心,录井,测井及化验分析资料,以现代沉积学和层序地层学理论为基础,对安塞王窑南长612层沉积微相精细研究,搞清了骨架相砂体类型和几何形态,总结了长612小层各沉积期沉积微相平面时空演化规律,确定其为一套三角洲沉积,其中三角洲前缘较为发育,进一步可以划分为水下分流河道,河口砂坝,远砂坝,水下天然堤,席状砂,水下分流河道间6种微相类型。通过沉积相带对油气的控制作用分析,指出有利的油气聚集带,为油气开发提供了方向。 相似文献
20.
对X射线辐照后的BaFCl:Eu样品,通过研究紫外线辐照对光激励发光的影响,发现在一定条件下紫外线对光激励发光有增强的作用,并且根据光谱研究提出了光激励发光的过程为Eu^2 和陷阱争夺激发态电子的观点,从机理上对这一现象进行了解释。 相似文献