全文获取类型
收费全文 | 763篇 |
免费 | 41篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 304篇 |
金属工艺 | 11篇 |
机械仪表 | 14篇 |
建筑科学 | 16篇 |
能源动力 | 31篇 |
轻工业 | 103篇 |
水利工程 | 3篇 |
石油天然气 | 4篇 |
无线电 | 61篇 |
一般工业技术 | 100篇 |
冶金工业 | 22篇 |
原子能技术 | 3篇 |
自动化技术 | 128篇 |
出版年
2023年 | 6篇 |
2022年 | 41篇 |
2021年 | 60篇 |
2020年 | 31篇 |
2019年 | 25篇 |
2018年 | 29篇 |
2017年 | 21篇 |
2016年 | 38篇 |
2015年 | 22篇 |
2014年 | 43篇 |
2013年 | 63篇 |
2012年 | 53篇 |
2011年 | 44篇 |
2010年 | 41篇 |
2009年 | 37篇 |
2008年 | 30篇 |
2007年 | 27篇 |
2006年 | 20篇 |
2005年 | 15篇 |
2004年 | 13篇 |
2003年 | 14篇 |
2002年 | 11篇 |
2001年 | 7篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1998年 | 9篇 |
1997年 | 4篇 |
1996年 | 9篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 6篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1972年 | 2篇 |
1971年 | 3篇 |
1959年 | 1篇 |
1939年 | 1篇 |
1937年 | 1篇 |
1933年 | 2篇 |
1916年 | 2篇 |
排序方式: 共有804条查询结果,搜索用时 15 毫秒
1.
2.
Photonic Network Communications - Optical packet switching is a prominent technology proposing not only a reduction in the energy consumption by the elimination of numerous... 相似文献
3.
Vitamin D Compounds PRI-2191 and PRI-2205 Enhance Anastrozole Activity in Human Breast Cancer Models
Beata Filip-Psurska Mateusz Psurski Artur Anisiewicz Patrycja Libako Ewa Zbrojewicz Magdalena Maciejewska Micha Chodyski Andrzej Kutner Joanna Wietrzyk 《International journal of molecular sciences》2021,22(5)
1,25-Dihydroxycholecalciferol, the hormonally active vitamin D3 metabolite, is known to exhibit therapeutic effects against breast cancer, mainly by lowering the expression of estrogen receptors and aromatase activity. Previously, the safety of the vitamin D active metabolite (24R)-1,24-dihydroxycholecalciferol (PRI-2191) and 1,25(OH)2D3 analog PRI-2205 was tested, and the in vitro activity of these analogs against different cancer cell lines was studied. We determined the effect of the two vitamin D compounds on anastrozole (An) activity against breast cancer based on antiproliferative activity, ELISA, flow cytometry, enzyme inhibition potency, PCR, and xenograft study. Both the vitamin D active metabolite and synthetic analog regulated the growth of not only estrogen receptor-positive cells (T47D and MCF-7, in vitro and in vivo), but also hormone-independent cancer cells such as SKBR-3 (HER-2-positive) and MDA-MB-231 (triple-negative), despite their relatively low VDR expression. Combined with An, PRI-2191 and PRI-2205 significantly inhibited the tumor growth of MCF-7 cells. Potentiation of the antitumor activity in combined treatment of MCF-7 tumor-bearing mice is related to the reduced activity of aromatase by both An (enzyme inhibition) and vitamin D compounds (switched off/decreased aromatase gene expression, decreased expression of other genes related to estrogen signaling) and by regulation of the expression of the estrogen receptor ERα and VDR. 相似文献
4.
Lydia Saidi Dr. Djenisa H. A. Rocha Dr. Oualid Talhi Dr. Yamina Bentarzi Prof. Dr. Bellara Nedjar-Kolli Dr. Khaldoun Bachari Dr. Filipe A. Almeida Paz Dr. Luisa A. Helguero Prof. Dr. Artur M. S. Silva 《ChemMedChem》2019,14(10):1041-1048
Breast and prostate cancers are frequently treated with chemotherapy. Several novel chemicals are being reported for this purpose, particularly synthetic and natural benzophenones. This work reports the synthesis of substituted 2-hydroxybenzophenones through 1,4-conjugate addition/intramolecular cycloaddition/dehydration of nitromethane on key intermediate chromones. Structures were extensively studied by means of 2D NMR spectroscopy and single-crystal XRD. Their cytotoxicity was evaluated in vitro in two breast cancer cell lines (MDA-MB-231 and T47-D) and one prostate cancer cell line (PC3). The most potent compound exhibited good cytotoxic effects against the three cancer cell lines (IC50 values ranging from 12.09 to 26.49 μm ) and induced cell-cycle retardation only on prostate cancer cells, which suggested that it might exert cell-type-specific effects. 相似文献
5.
Further evidence was delivered that certain impurities, which could be contained in MgO samples, might be responsible for observed variability in MgO basicity and catalytic performance in oxidative coupling of methane. The surface basicity/base strength distribution of a series of MgO samples containing or not containing Ca and Na impurities was determined by a temperature-programmed desorption of CO2. It was revealed that samples containing Ca and Na impurities have much more medium, strong and very strong basic sites. The surface basicity of MgO samples containing added alkali or alkaline earth compounds or water was characterized by a test reaction of transformation of 2-butanol. It was confirmed that the introduction of these compounds to a pure MgO enhanced both its basicity and activity in oxidative coupling of methane. 相似文献
6.
7.
Marek Markowski Ireneusz Bialobrzewski Janusz Bowszys Stanislaw Suchecki 《Drying Technology》2007,25(9):1527-1536
A neural-deterministic simulation model applied for calculating distributions of temperatures and moisture content in a bed of wheat stored in a steel silo without aeration is presented in the article. The model consists of differential equations of heat and moisture transfer, initial and boundary conditions, and three artificial neural networks used during simulated ambient air conditions. Experiments and computer simulations were carried out in order to determine temperature fields in wheat grain stored in a steel silo for two months. The computer simulations were carried using MATLAB and FEMLAB software. The difference between measured and simulated temperature in grain near the silo wall at a height of 2.5 m from the bottom was less than 3.0°C. On the basis of the analysis performed it was concluded that the temperature distributions obtained with the model were consistent with the measured results obtained for grain stored in a steel silo without aeration. 相似文献
8.
Maciej Winiewski Artur Jakubiak Jan Szymanowski 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1995,63(3):209-214
Decyl isonicotiniate and decyl nicotiniate permit a rapid extraction of palladium(II) from its hydrochloride solutions. Decyl picoliniate is not a suitable extractant. 4-Octylphenylamine can act as a phase transfer catalyst when its concentration in the organic phase is at least 2·5 × 10?4 M . It seems that the interfacial adsorption of pyridine carboxylates and of 4-octylphenylamine is not the decisive phenomenon in palladium(II) extraction. The negligible protonation of the pyridine-type extractants and the phase transfer catalysis explains well the quick extraction of palladium(II) with the commercial and highly hydrophobic extractant ACORGA CLX-50. 相似文献
9.
The paper presents investigations of the structure and properties of multicomponent and multilayer hard coatings based on Ta, Mo, Ti, W, Al and their nitrides, obtained using standard and improved bias activated reactive evaporation methods. The results of secondary ion mass spectrometry investigation as well as X-ray diffraction and energy-dispersive analysis of X-rays are presented. The potentiokinetic curves of deposited layers are also shown. 相似文献
10.
Artur Lugmayr Bjoern Stockleben Yaning Zou Sonja Anzenhofer Mika Jalonen 《Multimedia Tools and Applications》2014,71(1):119-157
“Design Thinking” – a cross-disciplinary and user centered method – is an approach towards the discovery of solutions and sparks innovative thinking in many ways. It also can be argued, that designers put themselves in the place of the user rather than co-creating with the consumer. Innovation is one of the current keywords across many industries, and many attempt to find new solutions to daily problems. Design Thinking as method allows to understand user needs and understand their principle problems in daily life. The design process uses intensive collaboration in cross-disciplinary settings and is divided into the exploration of the problem space and the solution space to achieve new ways of solving existing problems. Design Thinking has to integrate into the innovation process and into organizational structures right from the beginning. It constitutes a complement to classical analytical processes for problems that require lateral, not linear thinking. This article reviews the practical application of this energetic methodology in the academic context and presents some hands-on examples. The course series has been established by the Entertainment and Media Management Lab. (EMMi Lab.) at the Tampere University of Technology (TUT) and was held in cooperation with students from the University of Tampere (UTA), and the Tampere University of Applied Sciences (TAMK). One course has been held in cooperation with the University of Applied Sciences Magdeburg-Stendal, Germany. This article describes how to train students especially with strong technical background and analytical mind-sets in the development of innovations in the field of media, foster creative thinking, and achieve problem solutions beyond the current state of the art. We present the basic curriculum, course structure, goals & objectives, applied methods, settings, and theoretical aspects of Design Thinking. Our experience and reflections on conducting the courses concludes this article. The article shall be an introductory guide for anyone who intends to organize a similar course in the university context. 相似文献