全文获取类型
收费全文 | 1830篇 |
免费 | 135篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 28篇 |
综合类 | 5篇 |
化学工业 | 482篇 |
金属工艺 | 26篇 |
机械仪表 | 75篇 |
建筑科学 | 49篇 |
矿业工程 | 2篇 |
能源动力 | 167篇 |
轻工业 | 182篇 |
水利工程 | 13篇 |
石油天然气 | 31篇 |
无线电 | 177篇 |
一般工业技术 | 377篇 |
冶金工业 | 46篇 |
原子能技术 | 17篇 |
自动化技术 | 300篇 |
出版年
2024年 | 10篇 |
2023年 | 71篇 |
2022年 | 134篇 |
2021年 | 147篇 |
2020年 | 104篇 |
2019年 | 108篇 |
2018年 | 121篇 |
2017年 | 97篇 |
2016年 | 129篇 |
2015年 | 73篇 |
2014年 | 127篇 |
2013年 | 171篇 |
2012年 | 106篇 |
2011年 | 101篇 |
2010年 | 80篇 |
2009年 | 74篇 |
2008年 | 50篇 |
2007年 | 40篇 |
2006年 | 39篇 |
2005年 | 22篇 |
2004年 | 19篇 |
2003年 | 15篇 |
2002年 | 15篇 |
2001年 | 14篇 |
2000年 | 6篇 |
1999年 | 12篇 |
1998年 | 17篇 |
1997年 | 6篇 |
1996年 | 13篇 |
1995年 | 5篇 |
1994年 | 8篇 |
1993年 | 6篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
排序方式: 共有1977条查询结果,搜索用时 31 毫秒
991.
Akon Higuchi Qing-Dong Ling S. Suresh Kumar Murugan Munusamy Abdullah A. Alarfajj Akihiro Umezawa Gwo-Jang Wu 《Progress in Polymer Science》2014
This review describes recent developments regarding the use of natural and synthetic polymers to support the propagation of human pluripotent stem cells (hPSCs), human embryonic stem cells (hESCs), and induced pluripotent stem cells (hiPSCs) while maintaining pluripotency in feeder-free and xeno-free cultures. The development of methods for culturing these cells without using mouse embryonic fibroblasts (MEFs) as a feeder layer will enable more reproducible culture conditions and reduce the risk of xenogenic contaminants, thus increasing the potential clinical applications of differentiated hPSCs. Human or recombinant fibronectin, laminin-511, and vitronectin, which are components of the extracellular matrix (ECM), have been used instead of Matrigel for the feeder-free growth of undifferentiated hPSCs. Successful hPSC cultures have been described for the following conditions: on oligopeptide-immobilized surfaces derived from vitronectin, on microcarriers prepared from synthetic polymers, and encapsulated within three-dimensional (3D) hydrogels composed of alginate and other hydrophilic natural polymers. Recently, synthetic biomaterials that allow hPSCs to maintain pluripotency by secreting endogenous ECM components have been designed. The combination of human ECM proteins or cell adhesion molecules (e.g., oligopeptides and poly-d-lysine) and synthetic biomaterials with well-designed surfaces and/or structures (e.g., scaffolds, hydrogels, microcarriers, microcapsules, or microfibers) in the presence of a chemically defined medium containing recombinant growth factors would offer a xeno-free alternative to feeder cells for culturing hPSCs and maintaining their pluripotency. 相似文献
992.
Bioinspired,Ultrastrong, Highly Biocompatible,and Bioactive Natural Polymer/Graphene Oxide Nanocomposite Films
下载免费PDF全文
![点击此处可从《Small (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
993.
Anish Khan Aftab Aslam Parwaz Khan Abdullah M. Asiri Samia A. Kosa 《Polymer-Plastics Technology and Engineering》2015,54(15):1615-1624
A new class of PANI/Sn(II)SiO3/FCNTs nanocomposite was synthesized by mixing polyaniline into the gel of Sn(II)SiO3 followed by FCNTs (Polyaniline/Sn(II)SiO3/Functionalized Carbon nanotubes). The physico-chemical characterization was carried out by scanning electron microscope, XRD (X-ray Diffraction), FTIR (Fourier Transform Infrared Spectroscopy), ultraviolet–visible spectroscopy, and simultaneous thermogravimetric analysis studies. The ion-exchange capacity (1.2 meq/g) and distribution studies were also determined to understand the ion-exchange capabilities. The DC electrical conductivity studies revile it in the range of 3–5 × 10?3 S/cm. On the basis of distribution studies, ion-selective membrane electrode was designed for Hg(II). The analytical utility of this membrane was established by using it as an indicator electrode in electrometric titrations. 相似文献
994.
Solubilization of graphene flakes through covalent modification with well‐defined azido‐terminated poly(ε‐caprolactone)
下载免费PDF全文
![点击此处可从《应用聚合物科学杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Nabihah Abdullah Kazuya Hatano Daiki Ando Masataka Kubo Akira Koshio Fumio Kokai 《应用聚合物科学杂志》2015,132(9)
A well‐defined poly(ε‐caprolactone) (PCL) with terminal azido group was prepared. Grafting‐on reaction between the azido‐terminated PCL (N3? PCL) and ultrasonication‐assisted exfoliated graphene flakes (GF) was carried out to obtain PCL‐grafted‐GF (PCL‐g‐GF) which showed good dispersibility in a wide variety of organic solvents. Gel permeation chromatography, 1H NMR, IR, Raman, UV‐vis, and TEM measurements indicated that PCL macromolecules were covalently introduced on the surface of GF without disrupting the structure of GF. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41569. 相似文献
995.
Abdullah?Kurt Bekir?Yal?in Nihat?YilmazEmail author 《The International Journal of Advanced Manufacturing Technology》2015,81(1-4):315-327
Precision hard machining is an interesting topic in manufacturing die and mold, automobile parts, and scientific research. While the hard machining has benefit advantages such as short cutting cycle time, process flexibility, and low surface roughness, there are several disadvantages such as high tooling cost, need of rigid machine tool, high cutting stresses, and residual stresses. Especially, tool stresses should be understood and dealt with to achieve successful performance of finish hard turning with ceramic cutting tool. So, the influence of cutting parameters on cutting stresses during dry finish turning of hardened (52 HRC) AISI H13 hot work steel with ceramic tool is investigated in this paper. For this aim, a series finish turning tests were performed, and the cutting forces were measured in tests. After literature procedure about finite element model (FEM), FEM is established to predict cutting stresses in finish turning of hardened AISI H13 steel with Ceramic 650 grade insert. As shown, effect of the cutting parameters on cutting tool stresses in finish turning of AISI H13 steel is obtained. The suggested results are helpful for optimizing the cutting parameters and decreasing the tool failure in finish turning applications of hardened steel. 相似文献
996.
Gocer Abdullah Karamis M. Baki 《Protection of Metals and Physical Chemistry of Surfaces》2021,57(3):579-588
Protection of Metals and Physical Chemistry of Surfaces - Ceramic reinforcements are used in metal matrix composite materials to enhance the mechanical properties. Ceramic particles also improve... 相似文献
997.
Structure and Disorder in Squaraine–C60 Organic Solar Cells: A Theoretical Description of Molecular Packing and Electronic Coupling at the Donor–Acceptor Interface
下载免费PDF全文
![点击此处可从《Advanced functional materials》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Yao‐Tsung Fu Demetrio A. da Silva Filho Gjergji Sini Abdullah M. Asiri Saadullah Gary Aziz Chad Risko Jean‐Luc Brédas 《Advanced functional materials》2014,24(24):3790-3798
Organic solar cells based on the combination of squaraine dyes (as electron donors) and fullerenes (as electron acceptors) have recently garnered much attention. Here, molecular dynamics simulations are carried out to investigate the evolution of a squaraine–C60 bilayer interface as a function of the orientation and order of the underlying squaraine layer. Electronic couplings between the main electronic states involved in exciton dissociation and charge (polaron pair) recombination are derived for donor–acceptor complexes extracted from the simulations. The results of the combined molecular‐dynamics?quantum‐mechanics approach provide insight into how the degree of molecular order and the dynamics at the interface impact the key processes involved in the photovoltaic effect. 相似文献
998.
Interfaces: Structure and Disorder in Squaraine–C60 Organic Solar Cells: A Theoretical Description of Molecular Packing and Electronic Coupling at the Donor–Acceptor Interface (Adv. Funct. Mater. 24/2014)
下载免费PDF全文
![点击此处可从《Advanced functional materials》网站下载免费的PDF全文](/ch/ext_images/free.gif)
999.
Ariffuddin Joret Mohammad Faiz Liew Abdullah Muhammad Suhaimi Sulong Asmarashid Ponniran Siti Zuraidah Zainudin 《中国电子科技》2014,(1):90-94
Moments have been used in all sorts of object classification systems based on image. There are lots of moments studied by many researchers in the area of object classification and one of the most preference moments is the Zernike moment. In this paper, the performance of object classification using the Zernike moment has been explored. The classifier based on neural networks has been used in this study. The results indicate the best performance in identifying the aggregate is at 91.4% with a ten orders of the Zernike moment. This encouraging result has shown that the Zernike moment is a suitable moment to be used as a feature of object classification systems. 相似文献
1000.
The oxidation and carbonization stages of viscose rayon fibers were performed in the presence of 3 % phosphoric acid and 4 % boric acid (PA–BA) impregnation. The results showed that PA–BA impregnation enhanced thermal stability and prevented the evolution of volatile by-products. During the oxidation stage carried out at 250 °C, the cellulose II crystalline structure was totally lost due to the decrystallization process. Carbonization was carried out in a pure nitrogen atmosphere at temperatures ranging from 600 to 1000 °C. The results obtained from the fiber thickness, linear density, carbon fiber yield, elemental analysis, volume density, X-ray diffraction, infrared (IR) and Raman spectroscopy, tensile testing, and electrical conductivity measurements showed that the carbonization temperature had a significant effect on the structure and properties of the resulting carbon fibers. Carbon fibers obtained from the oxidized viscose rayon fibers showed physical and chemical transformations with increasing carbonization temperature and were characterized by a reduction in fiber thickness and linear density values due to the removal of non-carbon elements together with increases in the carbon content, carbon to hydrogen ratio (C/H), volume density, tensile strength, tensile modulus, and electrical conductivity values. X-ray diffraction analysis showed that the interplanar d-spacing (d 002) decreased, and that the apparent crystallite thickness (L c) and the apparent crystallite width (L a) increased with increasing temperature. IR spectroscopy in agreement with the elemental analysis showed the total loss of OH, CH, C=O, CH2, C–O, and C–O–C groups arising from the completion of dehydration and dehydrogenation reactions indicating total elimination of the cellulose structure and the formation of amorphous carbon during high temperature treatment. 相似文献