全文获取类型
收费全文 | 63431篇 |
免费 | 4732篇 |
国内免费 | 3367篇 |
专业分类
电工技术 | 3447篇 |
综合类 | 4639篇 |
化学工业 | 9518篇 |
金属工艺 | 6359篇 |
机械仪表 | 4557篇 |
建筑科学 | 5444篇 |
矿业工程 | 2147篇 |
能源动力 | 2903篇 |
轻工业 | 3630篇 |
水利工程 | 1177篇 |
石油天然气 | 2700篇 |
武器工业 | 383篇 |
无线电 | 5912篇 |
一般工业技术 | 10224篇 |
冶金工业 | 4252篇 |
原子能技术 | 1043篇 |
自动化技术 | 3195篇 |
出版年
2024年 | 254篇 |
2023年 | 645篇 |
2022年 | 1399篇 |
2021年 | 1630篇 |
2020年 | 1708篇 |
2019年 | 1399篇 |
2018年 | 1327篇 |
2017年 | 1846篇 |
2016年 | 1859篇 |
2015年 | 1967篇 |
2014年 | 3499篇 |
2013年 | 3651篇 |
2012年 | 4337篇 |
2011年 | 4861篇 |
2010年 | 3598篇 |
2009年 | 3678篇 |
2008年 | 3201篇 |
2007年 | 4133篇 |
2006年 | 3845篇 |
2005年 | 3234篇 |
2004年 | 2969篇 |
2003年 | 2585篇 |
2002年 | 2285篇 |
2001年 | 2090篇 |
2000年 | 1761篇 |
1999年 | 1496篇 |
1998年 | 1206篇 |
1997年 | 972篇 |
1996年 | 836篇 |
1995年 | 756篇 |
1994年 | 624篇 |
1993年 | 471篇 |
1992年 | 344篇 |
1991年 | 282篇 |
1990年 | 187篇 |
1989年 | 193篇 |
1988年 | 107篇 |
1987年 | 76篇 |
1986年 | 38篇 |
1985年 | 19篇 |
1984年 | 34篇 |
1983年 | 26篇 |
1982年 | 21篇 |
1981年 | 17篇 |
1980年 | 14篇 |
1979年 | 15篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1963年 | 4篇 |
1959年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
通过对接轨站设置位置和布置图型主要影响因素的分析。按照能够充分反映接轨站作业特点的交接方式。对接轨站所采用的布置图型进行了归纳和分类。 相似文献
2.
Edible film from water-soluble fish proteins were developed by casting film solution on leveled trays and effects of pH (9.5, 10.0 and 10.5), heating temperature (60, 70 and 80 °C), and heating time (10, 20 and 30 min) of the film solution on various film properties were determined using Response Surface Methodology (RSM). The impact of pH and heating temperature of film solution was more significant, overall, on the film's properties than heating time. Contour plots of tensile strength and elongation at break was highest at pH of 10.0 at 70 °C (2.75-3.02 MPa) but low in elongation at break (6.35-9.16%), while water vapor permeability and oxygen permeability were at their lowest (58.55-65.96 g mm/m2 d kPa and 351.33-624.18 cm3 μm/m2 d kPa). There was a direct correlation between the films’ and proteins’ solubility on one hand, and heating temperature of film solution on the other, which reversed with change in pH of film solution. Film color was darker and more yellowish with increase in the pH of film solution. 相似文献
3.
4.
1 Influence of PAMAon Boundary Fil mFormation and Friction1.1 Experi mental methodsUltra-thin optical interferometry has been used tostudy thinlubricating fil ms for more than a decade and theexperi mental details of this technique have been reportedpreviously[1].The principle of the test setup is shown inFigure1.A polished steel ball is loaded and rolled againstthe flat surface of a glass disc that is coated with a thinsemi-reflecting chromiumlayer and a silica spacer of about500nmthickne… 相似文献
5.
热镀锌板(卷)工程设计中的环境保护问题 总被引:1,自引:0,他引:1
对热镀锌板(卷)的生产工艺、主要生产设备进行了简要介绍,并就其污染源(工序)、生产过程中产生的污染物及其控制措施进行了评述,同时就设计和生产中宜注意的几个环保问题进行了分析。 相似文献
6.
A nonstationary model of SO2 absorption from a gas phase to a countercurrent falling film of absorbing slurry was developed. Laminar, wavy and turbulent film structures were considered based on published information. Resistances to the mass transfer on the gas and the liquid sides of the interphase were considered, together with chemical reactions in the liquid phase. Relevant chemical equilibria in the liquid phase were modeled. Original experimental data on the neutralization reagent dissolution rate presented as a polydispersed two‐phase system of solids and on the rate of dissolved sulfite oxidation were used. The model was verified with experimental data from a laboratory‐scale falling‐film absorber using a single vertical tube under various geometrical and operating conditions, and a very good agreement was found with the experiment. Parametric sensitivity analysis showed the critical parts of the model. 相似文献
7.
A.L. Pan H.G. ZhengZ.P. Yang F.X. Liu Z.J. Ding Y.T. Qian 《Materials Research Bulletin》2003,38(5):789-796
Small Ag particles or clusters dispersed mesoporous SiO2 composite films were prepared by a new method: First the matrix SiO2 films were prepared by sol-gel process combined with the dip-coating technique, then they were soaked in AgNO3 solutions followed by irradiation of γ-ray at room temperature and in ambient pressure. The structures of these films were examined by X-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), and optical absorption spectroscopy. It has been shown that the Ag particles grown within the porous SiO2 films are very small, and they are isolated and dispersed from each other with very narrow size distributions. With increasing the soaking concentration and an additional annealing, an opposite peakshift effect of the surface plasmon resonance (SPR) was observed in the optical absorption measurements. 相似文献
8.
The three-dimensional morphology of polyethylene single crystals grown from dilute solution has been examined by atomic force microscopy. Single crystals were deposited on a soft ground of aqueous solution of poly(vinyl alcohol) (PVA) to avoid the collapse of thin lamellar crystals with thickness of 10 nm. The observation of single crystals on dried PVA clarifies the morphology of a chair type crystal as well as well-known hollow pyramidal type. It has been confirmed that the screw dislocations in the chair type follow a selection rule of the handedness in a manner to relieve the distortion in the chair type. 相似文献
9.
根据石油开采业对石油机械产品的需求 ,利用机械理论基础知识 ,通过实践设计 ,提出了对几何尺寸长的金属管类进行调质处理后的均匀冷却方法 ,以满足其性能要求。 相似文献
10.
本文就利用诸如蛋白石这样的疏松多孔矿料同灰土构成的混合料,在路面结构中表现出的独特有效的抗冻作用机理作了深入分析,并结合足尺试验数据加以验证。阐述了所谓多孔板体结构的概念、机制和材料组成要求。 相似文献