全文获取类型
收费全文 | 2436篇 |
免费 | 303篇 |
国内免费 | 255篇 |
专业分类
电工技术 | 14篇 |
综合类 | 123篇 |
化学工业 | 900篇 |
金属工艺 | 409篇 |
机械仪表 | 100篇 |
建筑科学 | 21篇 |
矿业工程 | 45篇 |
能源动力 | 36篇 |
轻工业 | 81篇 |
水利工程 | 4篇 |
石油天然气 | 72篇 |
武器工业 | 39篇 |
无线电 | 182篇 |
一般工业技术 | 528篇 |
冶金工业 | 292篇 |
原子能技术 | 129篇 |
自动化技术 | 19篇 |
出版年
2024年 | 17篇 |
2023年 | 74篇 |
2022年 | 91篇 |
2021年 | 107篇 |
2020年 | 117篇 |
2019年 | 115篇 |
2018年 | 91篇 |
2017年 | 120篇 |
2016年 | 96篇 |
2015年 | 109篇 |
2014年 | 143篇 |
2013年 | 171篇 |
2012年 | 152篇 |
2011年 | 137篇 |
2010年 | 90篇 |
2009年 | 110篇 |
2008年 | 82篇 |
2007年 | 135篇 |
2006年 | 148篇 |
2005年 | 106篇 |
2004年 | 100篇 |
2003年 | 78篇 |
2002年 | 100篇 |
2001年 | 83篇 |
2000年 | 61篇 |
1999年 | 58篇 |
1998年 | 46篇 |
1997年 | 37篇 |
1996年 | 36篇 |
1995年 | 35篇 |
1994年 | 20篇 |
1993年 | 8篇 |
1992年 | 20篇 |
1991年 | 28篇 |
1990年 | 22篇 |
1989年 | 22篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1983年 | 4篇 |
1982年 | 1篇 |
1981年 | 4篇 |
1976年 | 1篇 |
1959年 | 3篇 |
排序方式: 共有2994条查询结果,搜索用时 31 毫秒
11.
12.
硼泥在混合砂浆中的应用 总被引:3,自引:0,他引:3
介绍硼泥混合砂浆的技术性能,通过试验,证明了硼泥在混合砂浆中的作用。 相似文献
13.
辽东含硼岩系条痕状角闪混合岩特征及其找矿意义 总被引:1,自引:1,他引:0
痕状角闪混合岩与其围岩变(浅)粒岩为渐变过渡关系.并呈现一些特殊的结构构造.其岩石化学成份变化波动性较大,说明岩石化学成分不稳定,与矿化含量的不稳定性一致.其特殊的岩石化学组成显示为混合岩特征.条痕状角闪混合岩石稀土总量ΣREE的平均值为207.18 ppm;(Ce/ΣY平均值为3.25;La/Yb为平均值为 6.48,δEu平均为 0.48,Eu/Sm平均值为0.16.这些特点与里尔峪组的各种变(浅)粒岩相似,是层状混合花岗岩. 相似文献
14.
根据冲天炉的冶金还原反应原理,在炉后加入廉价的硼矿石,代替昂贵的硼铁合金生产气缸套,取得显著的经济效益。 相似文献
15.
Shishan Xue Guanfei Liu Jingjuan Lai Peng An Yang Liu Yuanpeng Wu Yu Wang Zhiyong Ye Qiao Tang Hongwei Zhou 《大分子材料与工程》2021,306(11):2100415
Self-healing hydrogels often possess poor mechanical properties which largely limits their applications in many fields. In this work, boron nitride nanosheets are introduced into a network of the poly(vinyl alcohol)/borax (PVA/borax) hydrogels to enhance the mechanical properties of the hydrogel without compromising the self-healing abilities. The obtained hydrogels exhibit excellent mechanical properties with a tensile strength of 0.410 ± 0.007 MPa, an elongation at break of 1712%, a Young's Modulus of 0.860 ± 0.023 MPa, and a toughness of 3.860 ± 0.075 MJ m−3. In addition, the self-healing efficiency of the hydrogels is higher than 90% within 10 min at room temperature. Benefiting from the excellent self-healing properties, the shapeability of the hydrogel fragments is observed using different molds. In addition, the hydrogels display rapid pH-driven shape memory effects and can recover to their original shape within 260 s. Overall, this work provides a new approach to hydrogels with integrated excellent mechanical properties, self-healing abilities, and rapid pH-driven shape memory effects. 相似文献
16.
Asok Aparna A. S Sethulekshmi Jitha S. Jayan Appukuttan Saritha Kuruvilla Joseph 《大分子材料与工程》2021,306(11):2100429
Boron nitride (BN) is an eminent inorganic compound having many interesting characteristics such as improved oxidation resistance, mechanical strength, good thermal conductivity (TC), higher bandgap, high chemical stability, thermal stability, high hydrophobicity, and electrical insulation. The use of BN as a filler in polymers is a well-established strategy to tailor the properties of polymer composites. Recent studies depict an interesting urge to reap the synergistic effect of various nanofillers with BN in the form of hybrids. Hence the consolidation of the works on BN based hybrid fillers would definitely attract researchers so that these new filler systems could be transformed into useful polymer nanocomposites in future. This review article focuses on the synthesis and characterization of various boron nitride based hybrids in detail. Moreover, the review also throws light on different BN hybrid reinforced polymer nanocomposites (PNCs) and their thermal, electrical, electronic as well as biomedical applications in a detailed manner. Thus the review anticipates serving as a tool toward understanding the recent trends in the field of boron nitride hybrid based ternary polymer composites. 相似文献
17.
18.
19.
Costs in precision cylindrical grinding are compared for different abrasives, machines and grinding conditions. The analysis is for repeated batch production. Account is taken of machine cost and abrasive cost. Cost comparisons were based on extensive trials to assess re-dress life against workpiece quality requirements. Experiments show that different workpiece materials require different strategies to reduce costs. Easy-to-grind AISI 52100 and difficult-to-grind Inconel 718 materials were ground at conventional speeds and at high speeds. It is shown that wheel speed affects production rate through acceptable values of re-dress life, removal rate and dwell time. Advantages were gained using vitrified CBN at conventional speed and at high speed. For both materials, vitrified CBN wheels used at high speed, gave better quality at lower cost than conventional abrasives. Wheel costs became negligible and labour costs greatly reduced. Re-dress life trials, usually neglected, are shown to be essential to reduce costs and maintain quality [1]. 相似文献
20.