全文获取类型
收费全文 | 23846篇 |
免费 | 2209篇 |
国内免费 | 1076篇 |
专业分类
电工技术 | 981篇 |
综合类 | 1844篇 |
化学工业 | 7603篇 |
金属工艺 | 1419篇 |
机械仪表 | 553篇 |
建筑科学 | 2783篇 |
矿业工程 | 1657篇 |
能源动力 | 1773篇 |
轻工业 | 632篇 |
水利工程 | 1569篇 |
石油天然气 | 3221篇 |
武器工业 | 43篇 |
无线电 | 302篇 |
一般工业技术 | 1064篇 |
冶金工业 | 1082篇 |
原子能技术 | 182篇 |
自动化技术 | 423篇 |
出版年
2024年 | 60篇 |
2023年 | 262篇 |
2022年 | 519篇 |
2021年 | 635篇 |
2020年 | 629篇 |
2019年 | 520篇 |
2018年 | 534篇 |
2017年 | 604篇 |
2016年 | 757篇 |
2015年 | 709篇 |
2014年 | 1214篇 |
2013年 | 1445篇 |
2012年 | 1606篇 |
2011年 | 1650篇 |
2010年 | 1295篇 |
2009年 | 1265篇 |
2008年 | 1273篇 |
2007年 | 1455篇 |
2006年 | 1476篇 |
2005年 | 1272篇 |
2004年 | 1186篇 |
2003年 | 1090篇 |
2002年 | 980篇 |
2001年 | 864篇 |
2000年 | 669篇 |
1999年 | 591篇 |
1998年 | 490篇 |
1997年 | 396篇 |
1996年 | 353篇 |
1995年 | 307篇 |
1994年 | 233篇 |
1993年 | 164篇 |
1992年 | 146篇 |
1991年 | 105篇 |
1990年 | 94篇 |
1989年 | 64篇 |
1988年 | 44篇 |
1987年 | 66篇 |
1986年 | 24篇 |
1985年 | 19篇 |
1984年 | 17篇 |
1983年 | 8篇 |
1982年 | 8篇 |
1981年 | 2篇 |
1980年 | 5篇 |
1979年 | 11篇 |
1974年 | 1篇 |
1962年 | 1篇 |
1959年 | 2篇 |
1951年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
141.
S. Salar Behzadi Silvester Ölzant Reinhard Länger Christian Koban Frank M. Unger Helmut Viernstein 《European Food Research and Technology》2006,223(2):238-245
Inversion of sucrose is a stability problem particularly of candies with acidic taste that contain sucrose and small amounts of organic acids such as citric acid, since the free d-fructose produced by hydrolysis is hygroscopic. The following possibilities were investigated for preventing the hydrolysis of sucrose in tablets containing sucrose and citric acid: Adding various amounts of tri-sodium citrate to the formulation to neutralize the citric acid, (Hot) melt coating of citric acid and tri-sodium citrate with a vegetable fat at different coating ratios, variation of the ratio of coated citric acid and tri-sodium citrate in formulations, and compressing the formulations with different compression forces. After tablet processing and storage of tablets, the concentration of d-fructose was determined on the basis of enzymatic reactions. A response surface central composite design was used. The above-mentioned variations were chosen as independent variables and the amount of d-fructose was chosen as response variable. The lowest rates of inversion could be achieved by increasing the content of tri-sodium citrate and the ratio of coating material and decreasing the ratio of coated citric acid and tri-sodium citrate in the tablet formulations. The compression force had no significant effect on the inversion of sucrose. 相似文献
142.
143.
塔河油田三叠系水平井地质导向技术研究 总被引:3,自引:0,他引:3
针对塔河油田三叠系碎屑岩油气藏油层薄、储集层非均质性较强、泥质和低渗致密夹层纵横向变化大的地质特点,在分析、研究不同区块多口水平井资料的基础上,探讨了水平井不同地质情况下斜井段及目的层砂顶的预测和判别技术,以实例阐述了井眼轨迹调整方法,首次形成了一套适合于该地区碎屑岩非均质薄层油气藏水平井录井地质导向技术,在塔河油田水平井钻探开发中取得了显著的成效。 相似文献
144.
Athanasios Eftaxias Josep Font Agusti Fortuny Azael Fabregat Frank Stüber 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(6):677-687
The wet air oxidation of phenol over a commercial active carbon catalyst was studied in a trickle bed reactor (TBR) in the temperature and oxygen partial pressure ranges of 120–160 °C and 0.1–0.2 MPa, respectively. The performance of the active carbon was compared in terms of phenol and COD destruction. The weight change of active carbon due to reaction was also measured. Finally, oxic phenol adsorption isotherms were assessed in batch conditions at 25, 125 and 160 °C. In order to use the conversion data obtained from the TBR for a kinetic study, special care was taken to check the kinetic control in the TBR experiments. Several kinetic models including power law or Langmuir–Hinshelwood expressions were considered to describe the catalytic oxidation of phenol over active carbon. The simple power law model with first order dependence on both phenol and oxygen concentration predicted satisfactorily the experimental data not only over the entire range of operating conditions studied, but also outside its validity range. Copyright © 2005 Society of Chemical Industry 相似文献
145.
主要介绍了德国NEUMAG公司开发的新型高速卷统方式CPW(致密精密卷绕)的工艺技术特点,并对引进和应用该设备技术的生产情况及其产品质量做了对比分析. 相似文献
147.
根据南方风沙化地自然及气候的特点,提出并讨论了在风沙化土地区营造防风固沙林;建立沙地果业基地;发展沙区畜牧水产业;搞好沙地蔬菜生产;完善农防林体系建设,发展沙区工业等开发利用模式。 相似文献
148.
149.
Deterministic chaos theory offers useful quantitative tools to characterize the non-linear dynamic behavior of a fluidized bed and the developed complexity theory presents a new approach to evaluate finite sequences. In this paper,the non-linear,hydrodynamic behavior of the pressure flutuation signals in a reactor was discussed by chaos parameters and complexity measures.Coherent results were achieved by our multi-scale analysis,which further exposed the behavior in a gas-solid two-phase system. 相似文献
150.