全文获取类型
收费全文 | 23584篇 |
免费 | 1587篇 |
国内免费 | 880篇 |
专业分类
电工技术 | 549篇 |
技术理论 | 1篇 |
综合类 | 1755篇 |
化学工业 | 3593篇 |
金属工艺 | 734篇 |
机械仪表 | 2301篇 |
建筑科学 | 1823篇 |
矿业工程 | 682篇 |
能源动力 | 464篇 |
轻工业 | 4042篇 |
水利工程 | 590篇 |
石油天然气 | 737篇 |
武器工业 | 96篇 |
无线电 | 760篇 |
一般工业技术 | 2984篇 |
冶金工业 | 1480篇 |
原子能技术 | 291篇 |
自动化技术 | 3169篇 |
出版年
2024年 | 101篇 |
2023年 | 332篇 |
2022年 | 512篇 |
2021年 | 640篇 |
2020年 | 637篇 |
2019年 | 614篇 |
2018年 | 651篇 |
2017年 | 693篇 |
2016年 | 821篇 |
2015年 | 696篇 |
2014年 | 1117篇 |
2013年 | 1545篇 |
2012年 | 1417篇 |
2011年 | 1474篇 |
2010年 | 1310篇 |
2009年 | 1432篇 |
2008年 | 1198篇 |
2007年 | 1577篇 |
2006年 | 1564篇 |
2005年 | 1266篇 |
2004年 | 1175篇 |
2003年 | 1041篇 |
2002年 | 825篇 |
2001年 | 685篇 |
2000年 | 577篇 |
1999年 | 455篇 |
1998年 | 289篇 |
1997年 | 264篇 |
1996年 | 206篇 |
1995年 | 183篇 |
1994年 | 141篇 |
1993年 | 128篇 |
1992年 | 98篇 |
1991年 | 77篇 |
1990年 | 51篇 |
1989年 | 43篇 |
1988年 | 38篇 |
1987年 | 35篇 |
1986年 | 42篇 |
1985年 | 26篇 |
1984年 | 11篇 |
1983年 | 19篇 |
1982年 | 8篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1977年 | 2篇 |
1962年 | 2篇 |
1961年 | 2篇 |
1959年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
101.
This paper presents the results of an experimental investigation undertaken to evaluate different purging solutions to enhance the removal of multiple heavy metals, particularly chromium, nickel, and cadmium, from a low buffering clay, specifically kaolin, during electrokinetic remediation. Experiments were conducted on kaolin spiked with Cr(VI), Ni(II), and Cd(II) in concentrations of 1,000, 500, and 250 mg/kg, respectively, which simulate typical electroplating waste contamination. A total of five different tests were performed to investigate the effect of different electrode purging solutions on the electrokinetic remedial efficiency. A constant DC voltage gradient of 1 V/cm was applied for all the tests. The removal of heavy metals from the soil using tap water as the purging solution was very low. When 1 M acetic acid was used as the purging solution in the cathode, the removal of chromium, nickel, and cadmium was increased to 20, 19, and 13%, respectively. Using 0.1 M ethylene diamine tetraacetic acid as the purging solution in the cathode, 83% of the initial Cr was removed; however, the nickel and cadmium removal was very low. A sequentially enhanced electrokinetic remediation approach involving the use of water as a purging solution at both the anode and cathode initially, followed by the use of acetic acid as the cathode purging solution and a NaOH alkaline solution as the anode purging solution was tested. This sequential approach resulted in a maximum removal of chromium, nickel, and cadmium of 68–71, 71–73, and 87–94%, respectively. This study shows that the sequential use of appropriate electrode purging solutions, rather than a single electrode purging solution, is necessary to remediate multiple heavy metals in soils using electrokinetics. 相似文献
102.
Dielectric anisotropy phenomenon of coal was detectable by many dielectric measurements. The paper presented that it was attributed to coal interior moisture distribution. A new model describing interior moisture distribution was developed basing on microstructure observation of coal. In the model, coal interior moisture distribution was analyzed and simulated numerically, the relationship between interior moisture distribution and coal dielectric property was constructed, the character of the permittivity varying with moisture content had also been studied and coal dielectric anisotropy was deduced. Corresponding experiment results were well satisfied with the model analysis, demonstrating that the interior moisture content could cause coal dielectric anisotropy. 相似文献
103.
介绍了使用HMS87C1408B作为主控芯片的籽棉、菜籽和粮食水分综合测试仪的实现方法,重点说明了阻抗变换、软件驱动LCD和语音播报技术的实施. 相似文献
104.
105.
106.
107.
Preference mapping with 10 pears identified 3 segments among New Zealand consumers. While 1 segment preferred ripe European cultivars, another rejected only the seedling with strong off‐flavors. A 3rd segment combined the 2 former segments, but also rejected 2 hybrid samples. Survey responses to the question “To me, the ideal pear is ?” from a 2nd consumer sample confirmed the general preference for juicy and sweet pears, the key characteristics of ripeness. A separate appearance evaluation revealed 4 segments based on color and shape. Combining information from several sources resulted in suggestions for new breeding directions for pears, while highlighting the importance of appearance and the need for more extensive measurements. 相似文献
108.
David L. Spooner 《Journal of Intelligent Manufacturing》1994,5(1):13-21
A product database for a design and manufacturing enterprise serves as a repository for the data needed to manufacture a product. This paper discusses how an object-oriented persistent object manager named ROSE, under development at Rensselaer, has been used in the Rensselaer CIM program to develop a STEP/PDES-compliant product database for its research test bed. In so doing, it provides an overview of the requirements for a product database system in an integrated design and manufacturing facility, and it discusses how the chosen system meets these requirements. 相似文献
109.
丙烯酸接枝聚丙烯纤维的结构与性能 总被引:15,自引:2,他引:13
本文研究了用化学引发剂引发丙烯酸接枝聚丙烯纤维的某些影响因素。红外光谱分析表明,丙烯酸接枝在聚丙烯大分子链的叔碳原子上。X-射线衍射和DSC分析指出,纤维接枝后结晶度有所增加,接枝前纤维存在的β-变体转化成了α-变体,接枝纤维的吸湿性、离子交换容量和染色性随接枝率增加而增大。接枝纤维的力学性能有所下降。 相似文献
110.
叙述了利用MS-EXCEL通用电子表格软件中的规划求解模块优化油品调合的方法,并以汽油调合为例,说明构造数学模型的方法,以及实施优化求解的具体过程。 相似文献