全文获取类型
收费全文 | 5663篇 |
免费 | 530篇 |
国内免费 | 201篇 |
专业分类
电工技术 | 76篇 |
综合类 | 399篇 |
化学工业 | 1534篇 |
金属工艺 | 218篇 |
机械仪表 | 88篇 |
建筑科学 | 309篇 |
矿业工程 | 239篇 |
能源动力 | 49篇 |
轻工业 | 1806篇 |
水利工程 | 161篇 |
石油天然气 | 44篇 |
武器工业 | 11篇 |
无线电 | 324篇 |
一般工业技术 | 468篇 |
冶金工业 | 516篇 |
原子能技术 | 30篇 |
自动化技术 | 122篇 |
出版年
2024年 | 28篇 |
2023年 | 151篇 |
2022年 | 215篇 |
2021年 | 229篇 |
2020年 | 245篇 |
2019年 | 209篇 |
2018年 | 196篇 |
2017年 | 193篇 |
2016年 | 187篇 |
2015年 | 206篇 |
2014年 | 318篇 |
2013年 | 326篇 |
2012年 | 464篇 |
2011年 | 463篇 |
2010年 | 342篇 |
2009年 | 331篇 |
2008年 | 240篇 |
2007年 | 362篇 |
2006年 | 328篇 |
2005年 | 241篇 |
2004年 | 224篇 |
2003年 | 162篇 |
2002年 | 151篇 |
2001年 | 98篇 |
2000年 | 91篇 |
1999年 | 67篇 |
1998年 | 72篇 |
1997年 | 54篇 |
1996年 | 41篇 |
1995年 | 45篇 |
1994年 | 28篇 |
1993年 | 22篇 |
1992年 | 13篇 |
1991年 | 8篇 |
1990年 | 7篇 |
1989年 | 8篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1982年 | 5篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有6394条查询结果,搜索用时 15 毫秒
1.
Hassan Hajjaj Gerard Goma Jean M. François 《International Journal of Food Science & Technology》2015,50(8):1731-1736
In submerged cultures performed in chemically defined fermentation medium containing glucose and glutamate, the growth and production of water‐soluble red pigments and citrinin by the filamentous fungus Monascus ruber were studied under various carbon/nitrogen (C/N) ratios. The specific production of the red pigments was optimal at a glucose/glutamate ratio of about 10 and then steadily decreased at higher C/N ratio. In contrast, the production of the mycotoxin increased with increased C/N with an optimum in the range of 30–45. In a fed‐batch mode, it was also found that the production of pigments was not favoured in fed‐batch mode by feeding the medium with glucose while keeping the C/N ratio lower than 10. This low production likely resulted from concurrent high accumulation of L‐malic acid that was reported to inhibit this production. In contrast, this mode of cultivation was rather favourable for the production of the mycotoxin. 相似文献
2.
The work focuses on the synthesis of a red ceramic pigment by inclusion of hematite in a fumed silica matrix with different specific surface areas. Iron(II) sulfate was used as hematite precursor. Mixtures of iron(II) sulfate and fumed silica with different mole ratios were heated at different temperatures from 1000 to 1300 °C for 4 h. 相似文献
3.
Comments on the article "A house divided? The psychology of red and blue America" by D. C. Seyle and M. L. Newman (see record 2006-11202-001). Seyle and Newman concluded that the red and blue metaphor is inaccurate and proposed a purple America strategy to better convey that the majority of people do not align themselves with political extremes. There is interdisciplinary agreement on this. Although not cited by Seyle and Newman, the findings by Professor Fiorina of Stanford University were reported by the APA Monitor on Psychology in its coverage of the 2005 APA State Leadership Conference (Murray Law, 2005). In contrast to their social psychological analysis, Seyle and Newman were incorrect in concluding that "[a]s psychologists, we are not in a position to change either the elements of the American political system that may spur this conflict or even the decisions made by pundits, politicians, and reporters about the terms they choose to use in political discussion" (p. 579). (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
4.
论文介绍了一种针对铁水鱼雷罐车铁水液位检测的较为可行的低成本方案。采用车上间接称重、远红外非接触传输信号方式,解决了对移动铁水罐车进行实时监测的难题。 相似文献
5.
本文将2,3-酸在甲苯溶剂中用氯化亚砜酰氯化合成2-羟基萘-3-甲酰氯,将其分别和正丁胺、正辛胺、正十二胺和正十八胺反应制得4种不同碳链长度的2-羟基萘-3-甲酰烷基胺,用对硝基苯胺重氮盐与其偶合分别制得了对硝基苯偶氮2-羟基萘-3-甲酰正丁胺、对硝基苯偶氮2-羟基萘-3-甲酰正辛胺、对硝基苯偶氮2-羟基萘-3-甲酰正十二胺和对硝基苯偶氮2-羟基萘-3-甲酰正十八胺系聚丙烯纤维用红色染料。熔点分别为189.8℃、96.2℃、115.8℃和108.1℃;热分解点分别为273.1℃、216.0℃、258.0℃和221.0℃;最大吸收波长分别为515.8nm、516.8nm、513.6nm和514.2nm。在染色条件下,4支染料在聚丙烯纤维上的上染率分别37.6%、41.8%、42.4%和44.7%。 相似文献
6.
7.
YAG:Ce Phosphors for WLED via Nano-Pesudoboehmite Sol-Gel Route 总被引:5,自引:0,他引:5
The sub-micron sized YAG : Ce phosphors were synthesized via a modified sol-gel method by peptizing nano-pesudoboehmite particulate. It is found that YAG phase from the dried gel powders appears at 1000 ℃ then the pure YAG phase exists at a relatively lower sintering temperature of 1400 ℃. The smaller sizes of phosphors in the ranges of 1 - 3 μm are obtained due to the contribution of seeding effects of nano-sized alumina particles to strengthen each step of the processes. Both the excitation and emission spectra of photoluminescence of the phosphor obtained at 1400 ℃ meet well with the spectroscopic requirements of the WLED phosphors. 相似文献
8.
Y1.94-xMgxO2S:0.06Ti (0≤x≤0.10) phosphors with long afterglow were synthesized by solid state reaction route. The photoluminescence spectra, decay curves, thermoluminescent spectra and chromaticity coordinate curves were investigated. The results show that the luminescence intensity of Y1.94-xMgxO2S:0.06Ti (0≤x≤0.10) phosphors decrease gradually with increasing Mg2 ion content, and the shape of luminescence spectra and chromaticity coordinate change as well. Furthermore, two thermoluminescent peaks in single Ti-doped Y2O2S sample are found at 91.8 and 221.5 ℃, respectively. Nevertheless, significant different spectra were found for the Mg, Ti co-doped Y2O2S samples that three thermoluminescence peaks appear at 52.3, 141.7 and 226.8 ℃, respectively. These results indicate that the co-doped Mg ion changes the inherent trap depth of single Ti-doped Y2O2S:Ti phosphor, and induces simultaneously a new trap level in the Y1.94-xMgxO2S:0.06Ti phosphor. Based on the analysis of thermoluminescent spectra, photoluminescent spectra, decay curve and crystal structure defect, it was proposed that the varied structure defect and introduced new trap level by the doped Mg2 ions should be responsible for reducing luminescence intensity and varying color in the Y1.94-xMgxO2S:0.06Ti phosphor. 相似文献
9.
用FOSECS研究了中性红的光谱电化学特性,测定了它的热力学函数、条件平衡常数和参加电极反应的H^+数,其结果与文献值一致。 相似文献
10.
《中国稀土学报(英文版)》2022,40(5):709-716
A series of new oxyapatite red phosphors Ca3Y7(BO4)(SiO4)5O doped with different concentrations of Eu3+ were successfully synthesized by high temperature solid state method. The X-ray diffraction (XRD) Rietveld refinement results show that the structure of the phosphor belongs to space group P63/m and Eu3+ ion replaces Y3+ ion. The emission spectrum consists of the characteristic emission peaks corresponding to Eu3+ under the excitation of 274 nm and the dominant emission peak is at 614 nm (5D0→7F2 of Eu3+). The concentration quenching effect occurs and the optimized Eu3+ concentration is 4.0 mol%. The energy level diagram for luminous mechanism is also given and the non-radiative energy transfer mechanism between Eu3+ is mainly exchange interaction. The CIE coordinate is close to the ideal red light and the color purity is higher than 99.79%. Moreover, the phosphor exhibits moderate thermal stability because the photoluminescence intensity at 423 K is still maintained at higher than 78.97% of that at room temperature. The internal quantum efficiency of Ca3Y7(BO4)(SiO4)5O:4.0 mol%Eu3+ phosphor is 58.2%. A red light emitting diode (LED) device based on it can emit bright red light. The CCT values of the device are basically unchanged when driven by various bias current. The results show that Ca3Y7(BO4)(SiO4)5O:Eu3+ is a new type of oxyapatite red fluorescent material with good comprehensive performances. 相似文献