首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   25127篇
  免费   492篇
  国内免费   123篇
电工技术   535篇
综合类   66篇
化学工业   3581篇
金属工艺   984篇
机械仪表   741篇
建筑科学   615篇
矿业工程   70篇
能源动力   681篇
轻工业   2120篇
水利工程   231篇
石油天然气   187篇
武器工业   1篇
无线电   2766篇
一般工业技术   4408篇
冶金工业   6393篇
原子能技术   434篇
自动化技术   1929篇
  2022年   118篇
  2021年   242篇
  2020年   172篇
  2019年   209篇
  2018年   313篇
  2017年   316篇
  2016年   325篇
  2015年   243篇
  2014年   381篇
  2013年   949篇
  2012年   639篇
  2011年   894篇
  2010年   654篇
  2009年   717篇
  2008年   808篇
  2007年   821篇
  2006年   721篇
  2005年   767篇
  2004年   635篇
  2003年   673篇
  2002年   707篇
  2001年   695篇
  2000年   626篇
  1999年   651篇
  1998年   2238篇
  1997年   1456篇
  1996年   1100篇
  1995年   745篇
  1994年   641篇
  1993年   649篇
  1992年   363篇
  1991年   361篇
  1990年   364篇
  1989年   349篇
  1988年   298篇
  1987年   269篇
  1986年   250篇
  1985年   284篇
  1984年   220篇
  1983年   205篇
  1982年   192篇
  1981年   221篇
  1980年   205篇
  1979年   166篇
  1978年   156篇
  1977年   282篇
  1976年   393篇
  1975年   129篇
  1974年   111篇
  1973年   118篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
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   
2.
3.
4.
5.
Metal Science and Heat Treatment - The effect of solid boronizing at 950°C for 2 and 4 h on the phase composition, microstructure, hardness and abrasive wear of steel AISI 304L is studied...  相似文献   
6.
This study evaluated several physical and sensory parameters of different types of cheese available in the Polish market. The measurements of textural properties were conducted in an Instron universal testing machine, while the colour properties of cheeses were measured using a Minolta chromameter. The chemical composition was determined by means of the near‐infrared spectroscopy (NIRs). Moreover, a trained sensory panel was invited to assess the cheese texture‐related properties. Generally, cheeses with reduced fat content were characterised by higher hardness, adhesiveness, cohesiveness and elasticity. Texture‐related parameters of cheese with canola oil were comparable to that of most of full‐fat cheeses. The correlation analysis between physical and sensory attributes related to cheese textural properties indicated the potential applications of TPA, shear and penetration tests (= 0.766, = 0.75 and = 0.765, respectively) for the evaluation of sensory properties related to the hardness. Meanwhile, the elasticity of cheese obtained from sensory evaluation was strongly correlated with the elasticity determined from the shear test (= 0.722) and moderately correlated with the elasticity from penetration test (= 0.588), indicating a need to refine the method of penetration test. In addition, cheeses exhibited higher meltability during convection heating at 230 °C than microwave heating. The values of meltability for cheese with reduced fat content were lower than those of full‐fat cheese.  相似文献   
7.
8.
9.
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号