全文获取类型
收费全文 | 12091篇 |
免费 | 1402篇 |
国内免费 | 466篇 |
专业分类
电工技术 | 147篇 |
综合类 | 1340篇 |
化学工业 | 3179篇 |
金属工艺 | 245篇 |
机械仪表 | 332篇 |
建筑科学 | 4037篇 |
矿业工程 | 830篇 |
能源动力 | 270篇 |
轻工业 | 601篇 |
水利工程 | 290篇 |
石油天然气 | 584篇 |
武器工业 | 57篇 |
无线电 | 229篇 |
一般工业技术 | 840篇 |
冶金工业 | 365篇 |
原子能技术 | 280篇 |
自动化技术 | 333篇 |
出版年
2024年 | 37篇 |
2023年 | 151篇 |
2022年 | 275篇 |
2021年 | 373篇 |
2020年 | 388篇 |
2019年 | 352篇 |
2018年 | 293篇 |
2017年 | 385篇 |
2016年 | 427篇 |
2015年 | 433篇 |
2014年 | 724篇 |
2013年 | 829篇 |
2012年 | 930篇 |
2011年 | 960篇 |
2010年 | 654篇 |
2009年 | 675篇 |
2008年 | 635篇 |
2007年 | 763篇 |
2006年 | 687篇 |
2005年 | 585篇 |
2004年 | 492篇 |
2003年 | 443篇 |
2002年 | 350篇 |
2001年 | 326篇 |
2000年 | 273篇 |
1999年 | 239篇 |
1998年 | 191篇 |
1997年 | 293篇 |
1996年 | 145篇 |
1995年 | 118篇 |
1994年 | 87篇 |
1993年 | 66篇 |
1992年 | 73篇 |
1991年 | 59篇 |
1990年 | 51篇 |
1989年 | 51篇 |
1988年 | 38篇 |
1987年 | 24篇 |
1986年 | 14篇 |
1985年 | 7篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 17篇 |
1979年 | 8篇 |
1974年 | 3篇 |
1963年 | 1篇 |
1959年 | 4篇 |
1951年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
为解决长江高填方护岸深厚覆盖层地基的抗滑稳定问题,采用振冲置换法对地基进行加固处理。计算分析表明,振冲碎石桩处理范围、桩间距、桩长等参数应结合地形、地质条件进行设计,振冲置换法与其他地基处理方式进行有机结合能够取得更好的处理效果;护岸地基通过振冲置换处理后,抗滑稳定性能够满足规范要求。采用振冲碎石桩对软弱地基进行置换形成复合地基,能够有效解决地基砂土液化问题、承载力问题及抗剪强度问题。 相似文献
73.
74.
以某工程为算例,分别选取合理板柱与梁板结构计算模型,按照相关规范进行大型广场在平时工况与战时工况顶板各构件承载力计算,并对其两种结构型式的受力性能分析对比,以总结出地下人防结构顶板的适用原则,为实际工程设计提供参考依据。 相似文献
75.
Air bubble – bitumen attachment is a critical step in the flotation of bitumen from mined oil sand. In this study, single bubble – bitumen drop attachment was observed directly using a novel experimental technique. Induction time is determined and used as an indication of bubble‐bitumen attachment potency for both hydrogen and oxygen bubbles. The attachment tests were conducted in deaerated municipal water (City of Edmonton tap water) at temperatures ranging from 22–50°C. Induction times measured for hydrogen bubble attachment were shorter than those for oxygen bubbles. Coalescence tests were also conducted in the absence of bitumen, and showed that hydrogen bubbles coalesced more rapidly than oxygen bubbles in both deaerated municipal water and clear (solids‐free) process water. 相似文献
76.
77.
J.F. Rejl T. Moucha E. Prokopová L. Valenz F. Hovorka 《Chemical engineering science》2006,61(18):6096-6108
Volumetric mass transfer coefficients in liquid and vapour phases in distillation column were measured by the method consisting of a fitting of the concentration profile of liquid phase along the column obtained by the integration of a differential model to the experimental one. The mathematical model of distillation process includes mass and energy balances and the heat and mass transfer equations. The film model flux expressions with the convective transport contributions have been considered in the transfer equations. Vapour and liquid phases are supposed to be at their saturated temperatures along the column. Effect of changes of phase flows and physical properties of phases on the mass transfer coefficients along the column and non-ideal thermodynamic behaviour of the liquid phase have been taken into account. The concentration profiles of liquid phase are measured in the binary distillation of the ethanol-water and methanol-ethanol systems at total reflux on metal Pall Rings and Intalox saddles 25 mm in the column with diameter of 150 mm. The distillation mass transfer coefficients obtained by the fitting procedure are compared with those calculated from absorption data using Onda's, Billet's and Linek's correlations. The distillation heat transfer coefficients calculated from the model assuming saturated temperatures in both phases are compared with those calculated from the Chilton-Colburn and penetration model analogy between mass and heat transfer. The results have confirmed an agreement neither between distillation and from absorption correlations calculated mass transfer coefficients nor between analogy and from enthalpy balance calculated heat transfer coefficients. Also the concentration profiles obtained by the integration of the differential model of the distillation column using the coefficients from absorption correlation have differed from the experimental profiles considerably. 相似文献
78.
79.
This paper presents a comparative study how reactor configuration, sludge loading and air flowrate affect flow regimes, hydrodynamics, floc size distribution and sludge solids-liquid separation properties. Three reactor configurations were studied in bench scale activated sludge bubble column reactor (BCR), air-lift reactor (ALR) and aerated stirred reactor (ASR). The ASR demonstrated the highest capacity of gas holdup and resistance, and homogeneity in flow regimes and shearing forces, resulting in producing large numbers of small and compact flocs. The fluid dynamics in the ALR created regularly directed recirculation forces to enhance the gas holdup and sludge flocculation. The BCR distributed a high turbulent flow regime and non-homogeneity in gas holdup and mixing, and generated large numbers of larger and looser flocs. The sludge size distributions, compressibility and settleability were significantly influenced by the reactor configurations associated with the flow regimes and hydrodynamics. 相似文献
80.
In order to supplement the literature data on VLE, isobaric bubble temperature data were collected for the binary systems phenol-i-amyl alcohol and phenol-n-amyl alcohol over the entire composition range by indirect method using a standard Swietoslawski type ebulliometer. The measurements were made at three sub-atmospheric pressures. The experimental t-x data were correlated with both equation of state method and gamma-phi methods. In the former approach, the Soave equation of state is used, whereas in the latter case Wilson, NRTL and UNIQUAC equations are used. 相似文献