全文获取类型
收费全文 | 80076篇 |
免费 | 10066篇 |
国内免费 | 6674篇 |
专业分类
电工技术 | 5534篇 |
技术理论 | 1篇 |
综合类 | 9662篇 |
化学工业 | 10449篇 |
金属工艺 | 6160篇 |
机械仪表 | 6087篇 |
建筑科学 | 14226篇 |
矿业工程 | 3596篇 |
能源动力 | 1877篇 |
轻工业 | 2988篇 |
水利工程 | 3084篇 |
石油天然气 | 2612篇 |
武器工业 | 1233篇 |
无线电 | 4322篇 |
一般工业技术 | 9905篇 |
冶金工业 | 3872篇 |
原子能技术 | 347篇 |
自动化技术 | 10861篇 |
出版年
2024年 | 460篇 |
2023年 | 1292篇 |
2022年 | 2344篇 |
2021年 | 2731篇 |
2020年 | 2836篇 |
2019年 | 2389篇 |
2018年 | 2479篇 |
2017年 | 3140篇 |
2016年 | 3446篇 |
2015年 | 3497篇 |
2014年 | 4947篇 |
2013年 | 5247篇 |
2012年 | 6211篇 |
2011年 | 6165篇 |
2010年 | 4763篇 |
2009年 | 4791篇 |
2008年 | 4589篇 |
2007年 | 5514篇 |
2006年 | 4878篇 |
2005年 | 4127篇 |
2004年 | 3396篇 |
2003年 | 2844篇 |
2002年 | 2417篇 |
2001年 | 2141篇 |
2000年 | 1879篇 |
1999年 | 1554篇 |
1998年 | 1255篇 |
1997年 | 1052篇 |
1996年 | 867篇 |
1995年 | 737篇 |
1994年 | 623篇 |
1993年 | 495篇 |
1992年 | 375篇 |
1991年 | 280篇 |
1990年 | 256篇 |
1989年 | 236篇 |
1988年 | 135篇 |
1987年 | 95篇 |
1986年 | 38篇 |
1985年 | 43篇 |
1984年 | 49篇 |
1983年 | 35篇 |
1982年 | 35篇 |
1981年 | 16篇 |
1980年 | 36篇 |
1979年 | 34篇 |
1978年 | 5篇 |
1964年 | 4篇 |
1959年 | 5篇 |
1955年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
41.
42.
Aggregates of carbon black (CB) in a polymer matrix have a tendency to form a CB network. The dynamic mechanical properties of binary systems of chlorinated polyethylene (CPE) and CB or 3,9‐bis{1,1‐dimethyl‐2[β‐(3‐tert‐butyl‐4‐hydroxy‐5‐methylphenyl)propionyloxy]ethyl}‐2,4,8,10‐tetraoxaspiro[5,5]‐undecane (AO‐80) and their ternary systems were investigated. It was found that the dynamic mechanical properties of those systems depend on the colloidal properties, surface oxides, and surface modification of CB. For binary systems of CPE and CB, oxidized CB gives a high modulus at low strain amplitude and a large Payne effect compared with untreated CB. In contrast, the reverse effect was observed for their ternary systems. Consequently, a good micro‐dispersion is obtainable by surface modification due to physical adsorption of AO‐80 on oxidized CB particles via hydrogen bonds. © 2003 Society of Chemical Industry 相似文献
43.
Jorge Soriano-Santos† Setsuko Iwabuchi Kenshiro Fujimoto 《International Journal of Food Science & Technology》1992,27(3):337-346
Nitrogen was extracted more efficiently from amaranth seed with 0.04 M Na2 SO4 (5% w/v) than with either 0.09 M or 0.17 M NaCl (5% or 10% w/v), despite both solutions having the same ionic strength (μ= 1). Solubility of saline soluble proteins (albumin ± globulin) was very poor in either water or 1M NaCl, but increased in 0.4M NaCl at alkaline pH between 7 and 10. Globulins were very soluble in 0.4M NaCl at a pH 9. Albumin was the main storage protein. Saline soluble proteins formed very weak gels. 相似文献
44.
本文为了克服精馏塔静态仿真不易收敛和初值难以给定等难题,巧妙地利用隐含数值积分方法的特点,将稳态与动态数学模型耦合起来,用以求解高难度的非理想精馏塔静态仿真问题。所得静动态混俣模型大大提高了精馏塔静态仿真的鲁棒性,对于高度非理想精馏塔的仿真尤为有效。通过对某丙烯腈萃取精馏塔的静态仿真,充分证明了这种混合模型化方法的可行性。 相似文献
45.
预测控制算法的统一格式及其在电加热炉的应用 总被引:4,自引:0,他引:4
本文根据常用的两类预测控制算法推出一种新型预测控制算法。并将其应用于一双输入/双输出的力学持久机电加热炉的温度控制系统上,获得了满意的结果:控温精度为±1.5℃/300℃,且适用于非最小相位系统。 相似文献
46.
Evaluating Liquefaction Strength of Partially Saturated Sand 总被引:1,自引:0,他引:1
A method is presented for evaluating the liquefaction strength of partially saturated sand using the compression wave velocity (P-wave velocity), a new indicator of saturation. Based on laboratory test results, an empirical correlation that relates the liquefaction strength with the pore pressure coefficient B is firstly proposed. The strength is defined as the cyclic stress ratio required to cause liquefaction at a specified number of cycles. With the aid of a theoretical relation between B and the P-wave velocity, an explicit correlation of more interest is then established between the liquefaction strength of sand and its P-wave velocity. A comparison of the predictions using this explicit correlation with laboratory measurements shows a satisfactory agreement. The significance of this method lies in that it makes it possible to evaluate the liquefaction strength of sand as affected by saturation through the measurement of P-wave velocity, which can be made not only in the laboratory but particularly in the field. 相似文献
47.
Plastisols, which are a blend of poly(vinyl chloride) resin and a plasticizer (DEHP), were used as a toughening agent of a resol resin in order to improve the mechanical properties. It was not possible to formulate resol blends by adding more than 10 % of plastisol owing to a lack of apparent homogeneity in the systems, which also showed many air bubbles. The relationship between dynamic mechanical, mechanical and thermal properties and the amount of plastisol added was studied. It was determined from the infrared spectroscopy and dynamic mechanical results that the resol–plastisol blends seem to be formed by a reaction between the phenol and PVC giving a higher crosslinked structure. An improvement in the thermal resistance of the blends at lower temperatures was observed with an increase in the percentage of plastisol. Flexural analysis showed the elastic behaviour of the systems. However, it was not possible to observe the effect of the plasticizer (DEHP) owing to the low quantity of plastisol that was added to the resol. Copyright © 2004 Society of Chemical Industry 相似文献
48.
49.
50.