全文获取类型
收费全文 | 70888篇 |
免费 | 6049篇 |
国内免费 | 4020篇 |
专业分类
电工技术 | 4195篇 |
技术理论 | 1篇 |
综合类 | 6895篇 |
化学工业 | 11049篇 |
金属工艺 | 3859篇 |
机械仪表 | 4465篇 |
建筑科学 | 4914篇 |
矿业工程 | 1623篇 |
能源动力 | 1900篇 |
轻工业 | 6337篇 |
水利工程 | 1451篇 |
石油天然气 | 2785篇 |
武器工业 | 546篇 |
无线电 | 8524篇 |
一般工业技术 | 7515篇 |
冶金工业 | 3022篇 |
原子能技术 | 979篇 |
自动化技术 | 10897篇 |
出版年
2024年 | 217篇 |
2023年 | 759篇 |
2022年 | 1452篇 |
2021年 | 2053篇 |
2020年 | 1623篇 |
2019年 | 1459篇 |
2018年 | 1559篇 |
2017年 | 1794篇 |
2016年 | 1784篇 |
2015年 | 2486篇 |
2014年 | 3353篇 |
2013年 | 4052篇 |
2012年 | 4804篇 |
2011年 | 5175篇 |
2010年 | 4900篇 |
2009年 | 4833篇 |
2008年 | 4826篇 |
2007年 | 4636篇 |
2006年 | 4537篇 |
2005年 | 3810篇 |
2004年 | 3145篇 |
2003年 | 2830篇 |
2002年 | 3392篇 |
2001年 | 2955篇 |
2000年 | 2008篇 |
1999年 | 1446篇 |
1998年 | 942篇 |
1997年 | 785篇 |
1996年 | 707篇 |
1995年 | 615篇 |
1994年 | 451篇 |
1993年 | 333篇 |
1992年 | 266篇 |
1991年 | 205篇 |
1990年 | 172篇 |
1989年 | 108篇 |
1988年 | 106篇 |
1987年 | 78篇 |
1986年 | 32篇 |
1985年 | 52篇 |
1984年 | 41篇 |
1983年 | 31篇 |
1982年 | 19篇 |
1981年 | 19篇 |
1980年 | 18篇 |
1979年 | 14篇 |
1978年 | 8篇 |
1977年 | 12篇 |
1976年 | 15篇 |
1951年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
孟政 《武汉理工大学学报(材料科学英文版)》2013,28(1):79-81
The oxidation state of sulfur is detected in Na2O-CaO-SiO2 float glass by synchrotron radiation X-ray absorption near edge structure (XANES) spectra at the sulfur K edge. The measured spectra show the only presence of S6+ in the Na2O-CaO-SiO2 float glass and the oxidation state of sulfur do not change with the increase of glass depth. It is also found that, after the melt has gone through the molten tin bath, the S6+ is the dominant species, but S2- is also present on both surfaces. It is not certain whether cation bonds to S2- or not, because there are many cations dissolved in the melted tin which makes the spectrum complicated. 相似文献
102.
通过建立数值模型进行编程计算,分析了锅炉过热器/再热器管道在不同的管道几何尺寸、烟气温度、蒸汽流量和温度下,各个界面热流密度的变化情况。通过回归分析得到了热流密度与管道内壁侧氧化层厚度和运行时间的关系表达式,即热流密度的评估关系式。 相似文献
103.
从媒体控制考察媒体工作者的性观念与性道德,围绕媒体工作者的双重身份——普通大众与媒体人,对媒体工作者进行实证调查,分析得出媒体工作者的性观念与性道德总体上趋于保守和规范,但仍存在偏离现象。 相似文献
104.
通过文献检索、问卷调查等方式,将在校生对学校教学环境的满意度、对学校和专业的认同感、对学校教学活动的认同感、参与学校管理的意识、见习状况、教学成效等因素的满意度作为高校教学质量评估体系构成的主要内容,对云南省4所综合类高校的教学质量进行调查研究,探讨云南省综合类高校教学质量存在的问题,并在此基础上提出相应对策。 相似文献
105.
本文采用Brookfield RVT型旋转粘度计进行粘度测定,研究协合协增稠剂的流变性,将粘度数据进行计算机处理,回归出Casson方程,获得屈服值和无穷大剪切粘度,以描述增稠体系的遮盖力、稳定性、流平和流挂、沉降等性质,并对耐电解质性和后增稠进行了测试。本方法通过对粘度的测定,提供了一种对增稠剂的应用性能进行综合评价的途径。 相似文献
106.
在一致Fb-凸函数,一致Fb-伪凸和一致Fb-拟凸等广义凸性函数的基础上,研究了一类分式半无限规划问题,得到了涉及这些广义凸性函数的一类非光滑分式半无限规划的一些最优条件。 相似文献
107.
The recently established spin-coating electrostatic self-assembly (SCESA) technique has been shown to facilitate not only the rapid fabrication of polyelectrolyte multilayer assemblies, but also allow each layer to be easily controlled on a monomolecular scale by minimizing the film thickness across a substrate surface. In this paper, the influence of polyelectrolyte concentration on the amount and thickness of spin-deposited polymer films has been examined for a multilayer system of poly(allyamine hydrochloride) (PAH) and poly(sodium 4-styrenesulfonate) (PSS), when the washing steps employed for removing weakly bound polyelectrolytes on a resultant film on a substrate are excluded from the standard fabrication procedure of the SCESA method. The thickness of the spin-deposited PAH/PSS bilayer increased linearly for the PSS concentrations in the range from 1 to 10 mM with PAH constant at 1 mM, which demonstrates the uniform deposition of each layer material onto the thin film. The thickness of PAH/PSS bilayers increased from 1.43 ± 0.06 to 3.37 ± 0.08 nm as the PSS concentration increased from 1 to 10 mM, while the PAH concentration was kept constant at 1 mM. The multilayer films were found to be stable in a good solvent (H2O) for at least 30 h, without any noticeable loss of the adsorbed layer component of the polyelectrolyte. This improvement to the SCESA method (exclusion of washing steps) provides a convenient way to create multilayer heterostructures with the thickness of each layer being easily adjusted. 相似文献
108.
109.
Seogil Oh Jungwoo Moon Taewook Kang Surin Hong Jongheop Yi 《Journal of Electroceramics》2006,17(2-4):999-1003
The use of surface plasmon resonance (SPR) spectroscopy has been applied to a wide variety of fields such as biosensors and
surface analysis instruments. In general, a SPR substrate is prepared using self-assembled monolayer (SAM) method of organic
molecules as receptor for the target on a layer of gold or silver. However, mesoporous inorganic materials such as SBA-15
have benefits as sensor substrate for SPR. Mesoporous silica has a large surface area which receptor molecule can be attached
and has a rigid body which has an excellent stability in the extreme condition compared to organic sensing layer. We prepared
an organic modified mesoporous silica and successfully immobilized it on a gold surface, in an attempt to use as a substrate
for SPR spectroscopy. For the comparison of sensitivity of prepared substrate, Pt2+ detection was selected as a model system. Substrate prepared in this study exhibited the capability of selective sensing
for Pt2+ ions. 相似文献
110.
Ki-Won Kim Pyeong-Seok Cho Jong-Heun Lee Seong-Hyeon Hong 《Journal of Electroceramics》2006,17(2-4):895-898
A new method for preparing SnO2 whiskers by the decomposition of SnC2O4 is suggested. A Whisker-like morphology of a SnC2O4 precipitate was attained via the gradual addition of an oxalic acid solution to a hot SnCl2 aqueous solution (T > 50∘C). In comparison, when the solution temperature was either lower than 50∘C or when ethanol was used as the solvent, the SnC2O4 precipitate showed an angular and relatively isotropic morphology. The morphology of the SnC2O4 precipitate remained even after its thermal decomposition into SnO2 at 400∘C indicating that SnC2O4 precipitation is a key step in preparing the whiskers. The formation mechanism of SnO2 whiskers was explained by the supersaturation during the precipitation of SnC2O4. 相似文献