全文获取类型
收费全文 | 100805篇 |
免费 | 8746篇 |
国内免费 | 4964篇 |
专业分类
电工技术 | 4984篇 |
技术理论 | 12篇 |
综合类 | 9605篇 |
化学工业 | 16373篇 |
金属工艺 | 1688篇 |
机械仪表 | 2397篇 |
建筑科学 | 14398篇 |
矿业工程 | 7147篇 |
能源动力 | 5645篇 |
轻工业 | 5350篇 |
水利工程 | 19410篇 |
石油天然气 | 8114篇 |
武器工业 | 299篇 |
无线电 | 3329篇 |
一般工业技术 | 4573篇 |
冶金工业 | 4129篇 |
原子能技术 | 1149篇 |
自动化技术 | 5913篇 |
出版年
2024年 | 316篇 |
2023年 | 1116篇 |
2022年 | 2218篇 |
2021年 | 2758篇 |
2020年 | 2978篇 |
2019年 | 2471篇 |
2018年 | 2383篇 |
2017年 | 2943篇 |
2016年 | 3362篇 |
2015年 | 3464篇 |
2014年 | 6340篇 |
2013年 | 6275篇 |
2012年 | 7631篇 |
2011年 | 7724篇 |
2010年 | 5798篇 |
2009年 | 5961篇 |
2008年 | 5311篇 |
2007年 | 6958篇 |
2006年 | 6456篇 |
2005年 | 5831篇 |
2004年 | 4588篇 |
2003年 | 4197篇 |
2002年 | 3556篇 |
2001年 | 2861篇 |
2000年 | 2369篇 |
1999年 | 1836篇 |
1998年 | 1348篇 |
1997年 | 1085篇 |
1996年 | 849篇 |
1995年 | 757篇 |
1994年 | 560篇 |
1993年 | 436篇 |
1992年 | 334篇 |
1991年 | 261篇 |
1990年 | 193篇 |
1989年 | 199篇 |
1988年 | 126篇 |
1987年 | 134篇 |
1986年 | 105篇 |
1985年 | 112篇 |
1984年 | 100篇 |
1983年 | 61篇 |
1982年 | 35篇 |
1981年 | 13篇 |
1980年 | 24篇 |
1979年 | 23篇 |
1978年 | 6篇 |
1977年 | 15篇 |
1976年 | 9篇 |
1951年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
211.
212.
213.
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
214.
C. N. Haas B. F. Severin D. Roy R. S. Engelbrecht A. Lalchandani S. Farooq 《Water research》1985,19(3):323-329
This paper summarizes studies on the presence of acid-fast and yeast organisms in wastewater and water treatment plants and in surface water. These organisms were found to satisfy three of Bonde's criteria for indicator organisms: presence whenever pathogens are likely to be present; resistance at least equal to that of pathogens; and lack of regrowth in the post-treatment environment. This, plus prior data, indicates that these organisms are at least as acceptable as indicators of disinfection efficiency than the coliform group. 相似文献
215.
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
216.
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
217.
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
218.
219.
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
220.
The Environmental Effects Committee of the ASCE Energy Engineering Division has been developing a report on “Energy Production and Reservoir Water Quality” for publication. The report covers the regulatory framework that dictates much of the procedures for studies related to this topic, the fundamental reservoir hydrodynamics and water quality modeling used in preparing studies, the kinds of studies that can be prepared at different levels of analysis, and a series of applications that illustrate the problems encountered and applications of the various techniques. This study of hydrothermal modeling as applied to examining cooling tower alternatives for an existing steam electric station on a moderately large reservoir is included in this report and is presented here as an illustration of the types of studies included. This particular study subtended the usual steam electric plant cooling water discharge studies that relate to specific regulatory thermal plume size standards, and had to be designed around developing plant and cooling tower operations that would meet specific fisheries requirements for a zone of passage and refuge for fishes throughout the receiving embayment. After being used in developing cooling tower and plant operating details for the designers to work with, it was required that the hydrothermal modeling results be verified under actual tower operating conditions. In addition, it was required that the impact of the combined operations on dissolved oxygen be examined in detail. This paper covers the background to setting up the study, the kinds of statistical comparisons used to verify the hydrothermal studies, and similar studies for the analysis of dissolved oxygen distributions. 相似文献