全文获取类型
收费全文 | 6781篇 |
免费 | 2241篇 |
国内免费 | 486篇 |
专业分类
电工技术 | 144篇 |
综合类 | 234篇 |
化学工业 | 2083篇 |
金属工艺 | 463篇 |
机械仪表 | 217篇 |
建筑科学 | 93篇 |
矿业工程 | 62篇 |
能源动力 | 454篇 |
轻工业 | 292篇 |
水利工程 | 14篇 |
石油天然气 | 104篇 |
武器工业 | 50篇 |
无线电 | 1531篇 |
一般工业技术 | 3328篇 |
冶金工业 | 104篇 |
原子能技术 | 31篇 |
自动化技术 | 304篇 |
出版年
2024年 | 82篇 |
2023年 | 335篇 |
2022年 | 373篇 |
2021年 | 630篇 |
2020年 | 687篇 |
2019年 | 748篇 |
2018年 | 740篇 |
2017年 | 851篇 |
2016年 | 740篇 |
2015年 | 684篇 |
2014年 | 728篇 |
2013年 | 648篇 |
2012年 | 486篇 |
2011年 | 361篇 |
2010年 | 175篇 |
2009年 | 139篇 |
2008年 | 135篇 |
2007年 | 141篇 |
2006年 | 93篇 |
2005年 | 107篇 |
2004年 | 87篇 |
2003年 | 67篇 |
2002年 | 44篇 |
2001年 | 68篇 |
2000年 | 63篇 |
1999年 | 47篇 |
1998年 | 61篇 |
1997年 | 41篇 |
1996年 | 34篇 |
1995年 | 16篇 |
1994年 | 27篇 |
1993年 | 17篇 |
1992年 | 8篇 |
1991年 | 6篇 |
1990年 | 12篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1975年 | 1篇 |
1951年 | 9篇 |
排序方式: 共有9508条查询结果,搜索用时 15 毫秒
21.
针对炉型设计涉及的原始数据量庞大,合理炉型的界定范围广,界限模糊等问题,提出应用基于实例的推理方法辅助炉型初始方案的生成.分析了高炉炉型设计的特征属性,并建立了层次结构,针对其特征索引较多,权重系数小,检索效率低等问题,建立一种多层动态索引策略来改进传统的最近邻法,实现了炉型初始设计方案的智能生成.从而提高了相似实例检索的准确性和有效性,为后续对比调整提供了具有可比性和高参考价值的设计方案. 相似文献
22.
23.
人类能够与用户图像界面进行交互是依赖于一个清晰正常的视觉。然而,屈光不正(例如近视、远视、散光等)能使人眼视网膜中所显示的图像质量退化。图像质量的好坏严重影响了我们在军事、医学、娱乐领域所取得的研究成果。目前,对于人眼屈光度校正算法的研究主要有五种方法:1.应用一个维纳滤波的预补偿算法来校正人眼屈光度;2.用一个全变差的方法绘制图像对人眼屈光度进行校正;3.用视觉分析系统来校正人眼屈光度;4.使用多层显示器来校正视觉畸变;5.使用可计算的光场显示器来校正视觉畸变。通过研究这几种算法的优缺点提出现有算法的改进以及新的算法研究。 相似文献
24.
Cross-linked chitosan(CS),cross-linked chitosan/graphene(CS/RGO10) and cross-linked chitosan/graphene oxide(CS/GO10) were prepared as adsorbents for Cu(Ⅱ).The effects of pH,contact time,adsorbent dosage and initial concentration of Cu(Ⅱ) on the adsorbing abilities of CS,CS/RGO10 and CS/GO10 to Cu(Ⅱ) were investigated.The results demonstrate that the adsorption capacities of CS/GO10 and CS/RGO10 are greater than that of CS,especially at pH 5.0 and the adsorption capacities are 202.5,150 and 137.5 mg/g,respectively.Their behaviors obey the Freundlich isotherm model very well.Additionally,CS/GO10 has the shortest time to achieve adsorption equilibrium among them and can be used as a perspective adsorbent for Cu(Ⅱ). 相似文献
25.
Soubhik De Abhinav Omprakash Fulmali Krishna Chaitanya Nuli Rajesh Kumar Prusty B. Gangadhara Prusty Bankim Chandra Ray 《应用聚合物科学杂志》2021,138(15):50208
In this article, modification of carbon fiber surface by carbon based nanofillers (multi-walled carbon nanotubes [CNT], carbon nanofibers, and multi-layered graphene) has been achieved by electrophoretic deposition technique to improve its interfacial bonding with epoxy matrix, with a target to improve the mechanical performance of carbon fiber reinforced polymer composites. Flexural and short beam shear properties of the composites were studied at extreme temperature conditions; in-situ cryo, room and elevated temperature (−196, 30, and 120°C respectively). Laminate reinforced with CNT grafted carbon fibers exhibited highest delamination resistance with maximum improvement in flexural strength as well as in inter-laminar shear strength (ILSS) among all the carbon fiber reinforced epoxy (CE) composites at all in-situ temperatures. CNT modified CE composite showed increment of 9% in flexural strength and 17.43% in ILSS when compared to that of unmodified CE composite at room temperature (30°C). Thermomechanical properties were investigated using dynamic mechanical analysis. Fractography was also carried out to study different modes of failure of the composites. 相似文献
26.
Yasar Andelib Aydin 《应用聚合物科学杂志》2021,138(18):50339
Composite adsorbent films with amine and hydroxyl functionalities were synthesized from chitosan (CS), polyvinyl alcohol (PVA), and amine-modified carbon nanotubes (a-MWCNT) by solvent casting method. Weight proportions of CS to PVA and weight percent of a-MWCNT were optimized to achieve highest chromate removal capacity. Structural characteristics of the composites were investigated using scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and thermal gravimetric analysis. Accordingly, incorporation of a-MWCNT to CS/PVA structure resulted in the generation of nanochannels, which enhanced adsorption capacity. Moreover, the composite comprising 0.4% wt. a-MWCNT provided over 99% of Cr (VI) removal from 50 mg L−1 Cr (VI) solution within five minutes of contact time. Redlich–Peterson and Radke–Prausnitz isotherm models provided the highest conformity to adsorption data. Maximum chromate sorption capacity of CS/PVA/a-MWCNT composite film was determined as 134.2 mg g−1 being 172% higher than that of CS/PVA. Regeneration was best achieved in 1.0 M NaOH and the composite was shown to retain at least 70% of its original capacity after five consecutive adsorption–desorption cycles. 相似文献
27.
Yuji Ma Mei Fang Ming Huang Na Zhang Bo Lu Peipei Yang Chuntai Liu Changyu Shen 《应用聚合物科学杂志》2021,138(36):50924
Up to now, it is a major challenge to protect leading edge of the blades from solid particle erosion. Herein, we propose a structure optimization strategy to fabricate non-woven (NW) enhanced thermoplastic polyurethane nanocomposite films (thermoplastic polyurethane [TPU] - NW@G/Cx) with “sandwich - like” structure by hot pressing technology. TPU NW/graphene nanoplates/carbon nanotube (NW@G/Cx) interlayer film were first fabricated by spraying method. Then the interlayer film was laminated between TPU films to fabricate nanocomposite films. Such prepared TPU - NW@G/Cx film shows excellent solid particle erosion resistance and high-tensile strength. For example, the “steel-and-mortar” structure of NW fabric in TPU film results in high-tensile strength of 45 MPa and storage modulus of 21.2 MPa for TPU - NW@G/C1.0, increasing by 25% and 171% compared with original TPU film (35 MPa, 8 MPa), respectively. In addition, compared with pure TPU film, the “sandwich - like” structure endows TPU - NW@G/C1.2 with excellent solid particle erosion resistance and the thermal conductivity (0.251 W/m·K). These superior properties extends application of the TPU - NW@G/Cx film on wind turbine blades. 相似文献
28.
Soubhik De P.N. Shivangi Saswat Choudhury Abhinav Omprakash Fulmali Bankim Chandra Ray Rajesh Kumar Prusty 《应用聚合物科学杂志》2021,138(42):51231
Carbon fiber reinforced epoxy (CE) composite is ideal for a cryogenic fuel storage tank in space applications due to its unmatched specific strength and modulus. In this article, inter-laminar shear strength (ILSS) of carbon fiber/epoxy (CE) composite is shown to be considerably improved by engineering the interface with carboxyl functionalized multi-walled carbon nanotube (FCNT) using electrophoretic deposition technique. FCNT deposited fibers from different bath concentrations (0.3, 0.5, and 1.0 g/L) were used to fabricate the laminates, which were then tested at room (30°C) and in-situ liquid nitrogen (LN) (−196°C) temperature as well as conditioning for different time durations (0.25, 0.5, 1, 6, and 12 h) followed by immediate RT testing to study the applicability of these engineered materials at the cryogenic environment. A maximum increment in ILSS was noticed at bath concentration of 0.5 g/L, which was ~21% and ~ 17% higher than neat composite at 30°C and − 196°C, respectively. Short-term LN conditioning was found to be detrimental due to developed cryogenic shock, which was further found to be compensated by cryogenic interfacial clamping upon long-term exposure. 相似文献
29.
Hamza El Marouazi Benoit van der Schueren Damien Favier Anaëlle Bolley Samuel Dagorne Thierry Dintzer Izabela Janowska 《应用聚合物科学杂志》2021,138(44):51300
Four series of polylactide (PLA) based composite films containing horizontally aligned few layer graphene (FLG) flakes of high aspect ratio and adsorbed albumin are prepared. The mechanical and thermal properties varies with percentage, dispersion degree and size of FLG flakes. Great improvement up to 290% and 360% of tensile modulus and strength respectively were obtained for the composite containing high lateral size of FLG at 0.17% wt, and up to 60% and 80% for the composite with very well dispersed 0.02% wt FLG. The composites of PLA and PEG-PLLA containing very well dispersed FLG flakes at 0.07% wt are ductile showing enhancement of elongation at break up to respectively 80% and 88%. Relatively high electrical conductivity, 5 × 10−3 S/cm, is measured for PLA film charged with 3% of FLG. 相似文献
30.
Elaine C. Lopes Pereira Bluma G. Soares Adriana A. Silva Guilherme M. O. Barra 《应用聚合物科学杂志》2021,138(39):51164
Conducting polymer composites constituted by co-continuous poly (vinylidene fluoride) (PVDF)/ ethylene- vinyl acetate copolymer (EVA) blends with multiwalled carbon nanotube (CNT) were prepared by melt mixing using different procedures. The effect of the master batch approach on the conductivity, morphology, mechanical, thermal and rheological properties of PVDF/EVA/CNT nanocomposites was compared with that based on one step mixing strategy. The selective extraction experiments revealed that CNT was preferentially localized in the EVA phase in all situations, even when PVDF@CNT master batch was employed. Nanocomposites prepared with EVA@CNT master batch displayed higher conductivity, whose value reached around 10−1 S m−1 with the addition of 0.56 vol% of CNT. The better electrical performance was attributed to the better distribution of the filler, as indicated by transmission electron microscopy and rheological behavior. The electrical and rheological behavior were also investigated as a function of the CNT content. 相似文献