全文获取类型
收费全文 | 11702篇 |
免费 | 979篇 |
国内免费 | 226篇 |
专业分类
电工技术 | 465篇 |
综合类 | 1633篇 |
化学工业 | 2418篇 |
金属工艺 | 359篇 |
机械仪表 | 912篇 |
建筑科学 | 744篇 |
矿业工程 | 262篇 |
能源动力 | 438篇 |
轻工业 | 1075篇 |
水利工程 | 219篇 |
石油天然气 | 1082篇 |
武器工业 | 208篇 |
无线电 | 577篇 |
一般工业技术 | 1150篇 |
冶金工业 | 379篇 |
原子能技术 | 83篇 |
自动化技术 | 903篇 |
出版年
2024年 | 21篇 |
2023年 | 75篇 |
2022年 | 138篇 |
2021年 | 314篇 |
2020年 | 271篇 |
2019年 | 234篇 |
2018年 | 503篇 |
2017年 | 482篇 |
2016年 | 506篇 |
2015年 | 281篇 |
2014年 | 527篇 |
2013年 | 801篇 |
2012年 | 572篇 |
2011年 | 454篇 |
2010年 | 345篇 |
2009年 | 373篇 |
2008年 | 297篇 |
2007年 | 925篇 |
2006年 | 1190篇 |
2005年 | 634篇 |
2004年 | 894篇 |
2003年 | 1086篇 |
2002年 | 479篇 |
2001年 | 303篇 |
2000年 | 343篇 |
1999年 | 181篇 |
1998年 | 133篇 |
1997年 | 87篇 |
1996年 | 53篇 |
1995年 | 43篇 |
1994年 | 18篇 |
1993年 | 25篇 |
1992年 | 22篇 |
1991年 | 13篇 |
1990年 | 19篇 |
1989年 | 11篇 |
1988年 | 34篇 |
1987年 | 25篇 |
1986年 | 20篇 |
1985年 | 37篇 |
1984年 | 27篇 |
1983年 | 24篇 |
1982年 | 8篇 |
1981年 | 18篇 |
1980年 | 11篇 |
1979年 | 5篇 |
1978年 | 8篇 |
1976年 | 6篇 |
1974年 | 8篇 |
1973年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
Can Ercan S. Esra Safran Artuğ Türkmenoğlu Uğur Karabakal 《Journal of surfactants and detergents》2021,24(1):139-147
Garzan oil field is located at the south east of Turkey. It is a mature oil field and the reservoir is fractured carbonate reservoir. After producing about 1% original oil in place (OOIP) reservoir pressure started to decline. Waterflooding was started in order to support reservoir pressure and also to enhance oil production in 1960. Waterflooding improved the oil recovery but after years of flooding water breakthrough at the production wells was observed. This increased the water/oil ratio at the production wells. In order to enhance oil recovery again different techniques were investigated. Chemical enhanced oil recovery (EOR) methods are gaining attention all over the world for oil recovery. Surfactant injection is an effective way for interfacial tension (IFT) reduction and wettability reversal. In this study, 31 different types of chemicals were studied to specify the effects on oil production. This paper presents solubility of surfactants in brine, IFT and contact angle measurements, imbibition tests, and lastly core flooding experiments. Most of the chemicals were incompatible with Garzan formation water, which has high divalent ion concentration. In this case, the usage of 2-propanol as co-surfactant yielded successful results for stability of the selected chemical solutions. The results of the wettability test indicated that both tested cationic and anionic surfactants altered the wettability of the carbonate rock from oil-wet to intermediate-wet. The maximum oil recovery by imbibition test was reached when core was exposed 1-ethly ionic liquid after imbibition in formation water. Also, after core flooding test, it is concluded that considerable amount of oil can be recovered from Garzan reservoir by waterflooding alone if adverse effects of natural fractures could be eliminated. 相似文献
3.
4.
Multimedia Tools and Applications - Recently, many concepts in technology has been changed. According to the digital transformation trends, Internet of Things (IoT) represents an interested... 相似文献
5.
采用X射线荧光分析仪、X射线衍射仪、N2物理吸附仪、场发射扫描电子显微镜等仪器表征了苏州、广西和美国佐治亚州3个产地的高岭土,并以此3种高岭土为原料制备了模型催化裂化(FCC)催化剂,在ACE评价装置上对比了模型催化剂的反应性能。结果表明:苏州及广西高岭土主要组分为高岭石,佐治亚高岭土主要组分为地开石及珍珠陶土;苏州高岭土呈片状,还含有少量棒状颗粒;广西高岭土呈多层片状,晶粒粒径较大;佐治亚高岭土呈薄片状,晶粒粒径较小;3种高岭土制备的模型催化剂反应活性、Na2O及RE2O3质量分数相近;广西高岭土制备的模型催化剂具有最大的孔体积和磨损指数,但比表面积最小,具有较强的重油转化能力,其目标产物(液化气+汽油)和副产物(干气+焦炭)收率都高于苏州、佐治亚高岭土制备的催化剂的。 相似文献
6.
Uzun İlhan Orak İkram Yağmur Hatice Karaer Karakaplan Mehmet Yalman Murat 《SILICON》2021,13(12):4703-4713
Silicon - 5-(2,4-dichlorophenyl)-2-furoic acid and anthraquinone-2-carboxylic acid were reacted separately with chitin. The synthesized products were characterized by various spectroscopic methods... 相似文献
7.
8.
ABSTRACTThe thermal characterization of aluminum flat grooved heat pipes is performed experimentally for different groove dimensions. Three heat pipes with groove widths of 0.2?mm, 0.4?mm, and 1.5?mm are used in the experiments. The effect of the amount of the working fluid is extensively studied for each groove width. The results reveal that, although all three succeed in dissipating the heat input through the phase change of the working fluid by continuous evaporation and condensation, the effectiveness of the heat transfer increases with reduced groove width. Furthermore, it is observed that there exists an optimum operating point, where the temperature difference between the heating and cooling sections is at a minimum, and the magnitude of this temperature difference is a strong function of the groove width. To the best of the authors’ knowledge, the combined effects of groove dimensions and the amount of the working fluid, from fully flooded to dry, is reported for the first time for aluminum flat grooved heat pipes. 相似文献
9.
Some picture fuzzy Bonferroni mean operators with their application to multicriteria decision making
In this paper, we extend the Bonferroni mean (BM) operator with the picture fuzzy numbers (PFNs) to propose novel picture fuzzy aggregation operators and demonstrate their application to multicriteria decision making (MCDM). On the basis of the algebraic operational rules of PFNs and BM, we introduce some aggregation operators: the picture fuzzy Bonferroni mean, the picture fuzzy normalized weighted Bonferroni mean, and the picture fuzzy ordered weighted Bonferroni mean. Then, a new picture fuzzy MCDM method is proposed with the help of the proposed operators. Lastly, a practical application of proposed model is given to verify the developed model and related results of the proposed model is compared with the results of the existing models to indicate its applicability. 相似文献