全文获取类型
收费全文 | 99327篇 |
免费 | 8037篇 |
国内免费 | 4851篇 |
专业分类
电工技术 | 4976篇 |
技术理论 | 8篇 |
综合类 | 8498篇 |
化学工业 | 20916篇 |
金属工艺 | 1751篇 |
机械仪表 | 2273篇 |
建筑科学 | 13864篇 |
矿业工程 | 5212篇 |
能源动力 | 6255篇 |
轻工业 | 5574篇 |
水利工程 | 18873篇 |
石油天然气 | 8628篇 |
武器工业 | 213篇 |
无线电 | 1338篇 |
一般工业技术 | 4349篇 |
冶金工业 | 3489篇 |
原子能技术 | 3615篇 |
自动化技术 | 2383篇 |
出版年
2024年 | 284篇 |
2023年 | 1071篇 |
2022年 | 2100篇 |
2021年 | 2613篇 |
2020年 | 2928篇 |
2019年 | 2472篇 |
2018年 | 2398篇 |
2017年 | 2923篇 |
2016年 | 3278篇 |
2015年 | 3188篇 |
2014年 | 6028篇 |
2013年 | 6558篇 |
2012年 | 7249篇 |
2011年 | 7392篇 |
2010年 | 5512篇 |
2009年 | 5755篇 |
2008年 | 5066篇 |
2007年 | 6599篇 |
2006年 | 6158篇 |
2005年 | 5685篇 |
2004年 | 4443篇 |
2003年 | 4132篇 |
2002年 | 3599篇 |
2001年 | 2936篇 |
2000年 | 2409篇 |
1999年 | 1924篇 |
1998年 | 1408篇 |
1997年 | 1157篇 |
1996年 | 899篇 |
1995年 | 834篇 |
1994年 | 621篇 |
1993年 | 486篇 |
1992年 | 379篇 |
1991年 | 341篇 |
1990年 | 254篇 |
1989年 | 239篇 |
1988年 | 152篇 |
1987年 | 179篇 |
1986年 | 119篇 |
1985年 | 123篇 |
1984年 | 106篇 |
1983年 | 63篇 |
1982年 | 33篇 |
1981年 | 15篇 |
1980年 | 20篇 |
1979年 | 17篇 |
1977年 | 8篇 |
1976年 | 5篇 |
1959年 | 33篇 |
1951年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Yun‐Hwei Shen 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(5):581-586
A novel strategy of sweep coagulation to treat low turbidity water is presented herein. Study findings demonstrated that an Na+‐saturated bentonite with medium cation exchange capacity (CEC) resulted in significant turbidity removal at a bentonite dosage of 30 mg dm?3. Bentonite dispersion with fully delaminated platelets tended to undergo a more porous type of coagulation with intense face‐to‐face interactions of platelets and effectively entrapped TiO2 particles in band‐type structures. This type of coagulation usually results in a large volume of settled flocs with a fluffy structure and excellent turbidity removal efficiency for sweep coagulation. The sign and magnitude of electrical charge on TiO2 particles has a minor effect on the efficiency of sweep coagulation. Copyright © 2005 Society of Chemical Industry 相似文献
72.
Hung‐Yee Shu 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(3):273-280
Liquid–liquid two‐phase epoxidation from cyclohexene and cyclooctene in aqueous potassium peroxymonosulfate (commercially available as Oxone®) solution was studied as an application in pollution prevention. To avoid potential emissions of volatile organic compounds an aqueous solution was employed to replace the usual chlorinated solvents used in epoxide production. A droplet column reactor and stirred tank reactor were used to investigate two‐phase synthesis of epoxide. An aqueous Oxone® solution was used to oxidize a dispersion of alkene droplets and form epoxide. The study of aqueous epoxidation in both reactors showed that the epoxidation of alkenes can be represented as a first order reaction with respect to alkene. The salting out effect of Oxone® concentration was studied in both reactors and found to be very similar at optimal conditions. In comparing the two reactors, it was found that the droplet column reactor produces larger quantities of product per unit reactor volume for the same reaction time. The objective of this study is to provide an alternative reactor design and synthesis route that can meet pollution prevention goals. Copyright © 2004 Society of Chemical Industry 相似文献
73.
In this paper we present some preliminary results about the coupling of shallow water equations for free surface flows and Darcy equation for groundwater flows. A suitable set of interface conditions is discussed: the Beavers and Joseph formula for the bottom stress is used. An iterative algorithm to solve the coupled problem is proposed and some numerical results are presented. 相似文献
74.
介绍了天铁炼钢厂中间包水模实验原理和过程,分析了斜、直、圆三种型式挡渣墙模拟结果,提出了合理的挡渣控流方案,在生产实践中使用效果良好。 相似文献
75.
对两种煤代油方式——水煤浆和煤制混合煤气进行了燃料价格、设备投资及运行费用的分析对比。结果表明,两种代油方法均有可观的经济效益,燃料费用可分别节约52.4%和45.2%。如果原燃油工业炉窑由于工艺需要已装有除尘设备而又可用产生的蒸汽做雾化剂时,则水煤浆代油更具有经济优势。 相似文献
76.
77.
Catherine J. Harrison Yann A. Le Gouellec Robert C. Cheng Amy E. Childress 《Canadian Metallurgical Quarterly》2007,133(11):1004-1014
A dual-staged nanofiltration process is being evaluated as an alternative to reverse osmosis for seawater desalination. The primary goal of this system is to reduce energy consumption while producing potable water at an acceptable recovery rate. Investigation of this system at the bench-scale level focused on membrane surface characterization, ion rejection (including boron, bromide, and iodide rejection), and flux decline. Results from this study showed that two commercially available nanofiltration membranes can effectively desalinate seawater. Although fouling was apparent—and resulted in approximately 20% flux decline over 3 days—a critical flux was not identifiable. Operation of the system at different cross-flow velocities revealed the significance of hydrodynamic conditions on the polarization modulus, and hence on membrane performance. 相似文献
78.
79.
一种复合型数值方法的改进与算法实现 总被引:3,自引:1,他引:2
文中对原有的复合方法进行了改进,提出了一种新的复合型数值方法,这种方法解决了原方法求解含源项的问题时存在数值震荡的缺点。为了验证算法的有效性,对计算流体力学中一阶浅水波问题的两个典型的算例进行了数值模拟,在解的光滑性、锐利性等几个方面做了分析,结果表明改进后的方法既消除了数值震荡现象,又能准确地逼近真解,求出锐利的间断,是一种行之有效的数值方法。 相似文献
80.
官泓 《有色冶金设计与研究》2003,24(3):49-51
阐述水厂设计中对水厂规模、水源地、净水厂位置及净水工艺的确定过程,根据原水的特点,通过分析对无阀滤池进行改良。 相似文献