全文获取类型
收费全文 | 2377篇 |
免费 | 98篇 |
国内免费 | 15篇 |
专业分类
电工技术 | 28篇 |
综合类 | 9篇 |
化学工业 | 525篇 |
金属工艺 | 71篇 |
机械仪表 | 89篇 |
建筑科学 | 73篇 |
矿业工程 | 8篇 |
能源动力 | 209篇 |
轻工业 | 372篇 |
水利工程 | 20篇 |
石油天然气 | 25篇 |
无线电 | 149篇 |
一般工业技术 | 487篇 |
冶金工业 | 86篇 |
原子能技术 | 35篇 |
自动化技术 | 304篇 |
出版年
2024年 | 10篇 |
2023年 | 43篇 |
2022年 | 86篇 |
2021年 | 104篇 |
2020年 | 98篇 |
2019年 | 97篇 |
2018年 | 129篇 |
2017年 | 125篇 |
2016年 | 111篇 |
2015年 | 76篇 |
2014年 | 89篇 |
2013年 | 222篇 |
2012年 | 149篇 |
2011年 | 151篇 |
2010年 | 111篇 |
2009年 | 145篇 |
2008年 | 153篇 |
2007年 | 109篇 |
2006年 | 81篇 |
2005年 | 62篇 |
2004年 | 44篇 |
2003年 | 42篇 |
2002年 | 24篇 |
2001年 | 16篇 |
2000年 | 19篇 |
1999年 | 14篇 |
1998年 | 28篇 |
1997年 | 16篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 7篇 |
1993年 | 12篇 |
1992年 | 14篇 |
1991年 | 11篇 |
1990年 | 8篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 7篇 |
1986年 | 10篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 6篇 |
1979年 | 3篇 |
1976年 | 3篇 |
1971年 | 1篇 |
1970年 | 3篇 |
1968年 | 1篇 |
1967年 | 3篇 |
排序方式: 共有2490条查询结果,搜索用时 15 毫秒
41.
Lorenzo Landini Daniel Souza Monteiro de Araujo Mustafa Titiz Pierangelo Geppetti Romina Nassini Francesco De Logu 《International journal of molecular sciences》2022,23(9)
The transient receptor potential ankyrin 1 (TRPA1), a member of the TRP superfamily of channels, is primarily localized in a subpopulation of primary sensory neurons of the trigeminal, vagal, and dorsal root ganglia, where its activation mediates neurogenic inflammatory responses. TRPA1 expression in resident tissue cells, inflammatory, and immune cells, through the indirect modulation of a large series of intracellular pathways, orchestrates a range of cellular processes, such as cytokine production, cell differentiation, and cytotoxicity. Therefore, the TRPA1 pathway has been proposed as a protective mechanism to detect and respond to harmful agents in various pathological conditions, including several inflammatory diseases. Specific attention has been paid to TRPA1 contribution to the transition of inflammation and immune responses from an early defensive response to a chronic pathological condition. In this view, TRPA1 antagonists may be regarded as beneficial tools for the treatment of inflammatory conditions. 相似文献
42.
Cagatay Yelkarasi Nina Recek Kursat Kazmanli Janez Kova
Miran Mozeti
Mustafa Urgen Ita Junkar 《International journal of molecular sciences》2022,23(9)
Nanoporous ceramic coatings such as titania are promoted to produce drug-free cardiovascular stents with a low risk of in-stent restenosis (ISR) because of their selectivity towards vascular cell proliferation. The brittle coatings applied on stents are prone to cracking because they are subjected to plastic deformation during implantation. This study aims to overcome this problem by using a unique process without refraining from biocompatibility. Accordingly, a titanium film with 1 µm thickness was deposited on 316 LVM stainless-steel sheets using magnetron sputtering. Then, the samples were anodized to produce nanoporous oxide. The nanoporous oxide was removed by ultrasonication, leaving an approximately 500 nm metallic titanium layer with a nanopatterned surface. XPS studies revealed the presence of a 5 nm-thick TiO2 surface layer with a trace amount of fluorinated titanium on nanopatterned surfaces. Oxygen plasma treatment of the nanopatterned surface produced an additional 5 nm-thick fluoride-free oxide layer. The samples did not exhibit any cracking or spallation during plastic deformation. Cell viability studies showed that nanopatterned surfaces stimulate endothelial cell proliferation while reducing the proliferation of smooth muscle cells. Plasma treatment further accelerated the proliferation of endothelial cells. Activation of blood platelets did not occur on oxygen plasma-treated, fluoride-free nanopatterned surfaces. The presented surface treatment method can also be applied to other stent materials such as CoCr, nitinol, and orthopedic implants. 相似文献
43.
Yongchao Tang Yue Wei Anthony F.Hollenkamp Mustafa Musameh Aaron Seeber Tao Jin Xin Pan Han Zhang Yanan Hou Zongbin Zhao Xiaojuan Hao Jieshan Qiu Chunyi Zhi 《纳微快报(英文)》2021,(11):280-293
As promising anodes for sodium-ion batteries, metal sulfides ubiquitously suffer from low-rate and high-plateau issues, greatly hindering their application in f... 相似文献
44.
Esra Maltas Mustafa Ozmen Hasibe Cingilli Vural Salih Yildiz Mustafa Ersoz 《Materials Letters》2011,65(23-24):3499-3501
The magnetite (Fe3O4) nanoparticles were prepared by the co-precipitation of ferrous and ferric salts with NH4OH, and then modified with 3-aminopropyltriethoxysilane (APTES) by silanization reaction and subsequent reaction with glutaraldehyde (GA) to obtain functional groups on their surface. The influence of different terminated groups on protein binding was studied with bare and modified magnetite nanoparticles. Amine terminated magnetite nanoparticles were shown the highest binding ability for immobilization process compared to Fe3O4 NPs and GA bonded NPs. This binding ability was shown by using sodium dodecyl polyacrylamide gel electrophoresis technique (SDS-PAGE). Albumin attached magnetite nanoparticles were also examined by Scanning Electron Microscopy (SEM). 相似文献
45.
Mustafa Aslan Gary Chinga-Carrasco Bent F. S?rensen Bo Madsen 《Journal of Materials Science》2011,46(19):6344-6354
Due to the typical large variability in the measured mechanical properties of flax fibres, they are often employed only in low grade composite applications. The present study aims to investigate the reasons for the variability in tensile properties of flax fibres. It is found that an inaccuracy in the determination of the cross-sectional area of the fibres is one major reason for the variability in properties. By applying a typical circular fibre area assumption, a considerable error is introduced into the calculated mechanical properties. Experimental data, together with a simple analytical model, are presented to show that the error is increased when the aspect ratio of the fibre cross-sectional shape is increased. A variability in properties due to the flax fibres themselves is found to originate from the distribution of defects along the fibres. Two distinctive types of stress–strain behaviours (linear and nonlinear) of the fibres are found to be correlated with the amount of defects. The linear stress–strain curves tend to show a higher tensile strength, a higher Young’s modulus, and a lower strain to failure than the nonlinear curves. Finally, the fibres are found to fracture by a complex microscale failure mechanism. Large fracture zones are governed by both surface and internal defects; and these cause cracks to propagate in the transverse and longitudinal directions. 相似文献
46.
This paper presents the synthesis and characterization of three new Y-based high temperature-superconducting compounds having relatively higher transition temperature T c compared with that of the Y-123, Y-124, and Y-247. The electrical resistivity measurements indicate the onset critical temperatures as high as 98 K. Atomic compositions of these new Y-Ba-Cu-O superconductors are Y2Ba3Cu5.2O x , Y2Ba5Cu9O x , and YBa4Cu5O x . The X-ray analysis has shown that they have a similar crystalline structure as Y-123 phases. 相似文献
47.
A Self Organizing Map (SOM), is a machine learning method that represents high-dimensional data in low-dimensional form without losing topological relations of the data. After an unsupervised learning process, it organizes the data on the basis on similarity. In the current study, a SOM based algorithm has been developed which not only produces 2-D maps to analyze the relationship between various factors and crew productivity, but also predicts productivity under given conditions. Validation of the model has been achieved both by using artificial data set and data from 144 concrete pouring, 101 formwork and 101 reinforcement crews. The results show that maps which are produced by the model are satisfactory in clustering the data and prediction performance of the model is superior to similar artificial neural network models. 相似文献
48.
The proper optimization criterion to be chosen for the optimum design of the heat engines may differ depending on their purposes and working conditions. In this study, a comparative performance analysis is carried out for a reversible Otto cycle based on three alternative performance criteria namely maximum power (mp), maximum power density (mpd) and maximum efficient power (mep). The power density criterion is defined as the power per minimum specific volume in the cycle and the efficient power criterion is defined as multiplication of the power by the efficiency of the Otto cycle. Maximizing the efficient power gives a compromise between power and efficiency. Three different objective functions are defined and maximization of these functions is carried out under different design parameters of the Otto engine. The variations of power, power density and efficient power outputs are derived and presented with respect to the thermal efficiency of the cycle for various temperature ratios. It has been found that the design parameters at mep conditions lead to more efficient engines than that at the mp condition and the mep criterion may have a significant power advantage compared with mpd criterion. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
49.
Ring Opening of Epoxidized Soybean Oil with Compounds Containing Two Different Functional Groups 下载免费PDF全文
Kemal Karadeniz Hatice Akı Mustafa Yasin Sen Yakup Çalıkoğlu 《Journal of the American Oil Chemists' Society》2015,92(5):725-731
Epoxidized vegetable oils are desirable chemicals due to their eco‐friendly characteristics and their being a major source of many green products. Ring opening is one of the ways to convert these epoxidized oils to some new intermediates. The use of mono‐functional amines, alcohols, acid anhydrides and thioethers for epoxy ring opening has been reported in the literature. In this study, thioglycolic acid (TGA) bearing thiol and carboxylic acid as two different functional groups and methyl ester of thioglycolic acid (TGAME) were used. Currently, there is no reported literature describing epoxy ring opening using chemicals bearing two different functional groups simultaneously. In this way, two new polyols were synthesized, one with TGA (polyol 1) and one with TGAME (polyol 2). FTIR and 1H‐ and 13C‐NMR spectroscopy confirmed that the ring was opened by the carboxylic acid group of TGA, and the thiol group was not involved in the ring opening whereas the ring was opened by the thiol group in the case of TGAME. 相似文献
50.
Changes in Volatile Compounds of Black Cumin Oil and Hazelnut Oil by Microwave Heating Process 下载免费PDF全文
Mustafa Kiralan S. Sezer Kiralan 《Journal of the American Oil Chemists' Society》2015,92(10):1445-1450
Black cumin and hazelnut oils were subjected to a heating process in a microwave oven for a duration of 2, 4, 6 and 8 min at a constant frequency of 2450 MHz and a power of 0.45 kW. The ultraviolet absorption and volatile products of the oils were investigated in detail during the processes. The experimental evidences obtained show that K232 and K270 parameters reach values of 4.69 and 1.30 for black cumin oil, 3.22 and 1.75 for hazelnut oil, respectively with the increment of heating time. The headspace SPME method was used to analyze volatile compounds extracted from black cumin and hazelnut oils being exposed to the microwave heating process. The SPME–GC/MS method allowed the detection of 17 identified volatile compounds (hexanal, α‐thujene, α‐pinene, sabinene, β‐pinene, 2‐heptenal, α‐terpinene, limonene, p‐cymene, γ‐terpinene, E‐2‐octenal, nonanal, 4‐terpineol, thymoquinone, E,E‐2,4‐decadienal, α‐longipinene and isolongifolene) in black cumin oils. Of the products, hexanal, 2‐heptenal, E‐2‐octenal, nonanal and E,E‐2,4‐decadienal were determined to be the predominant volatile oxidation products. In fact, the hexanal was found as a major volatile oxidation compound and reached a local maximum point of 7.41 × 106 AU at the end of heating. On the other hand, only 8 volatile oxidation products (hexanal, heptanal, 2‐heptenal, nonanal, E‐2‐decenal, E,Z‐2,4‐decadienal, E,E‐2,4‐decadienal and E‐2‐tridecenal) were identified in hazelnut oils as a consequence of the heating process. Based on the experimental evidence observed, it is reasonable to conclude that the nonanal content dramatically increased at the end of heating and reached a value of 9.22 × 106 AU. 相似文献