全文获取类型
收费全文 | 1099篇 |
免费 | 4篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 14篇 |
综合类 | 3篇 |
化学工业 | 291篇 |
金属工艺 | 38篇 |
机械仪表 | 20篇 |
建筑科学 | 34篇 |
能源动力 | 40篇 |
轻工业 | 74篇 |
水利工程 | 5篇 |
石油天然气 | 1篇 |
无线电 | 145篇 |
一般工业技术 | 226篇 |
冶金工业 | 51篇 |
原子能技术 | 18篇 |
自动化技术 | 144篇 |
出版年
2023年 | 7篇 |
2022年 | 11篇 |
2021年 | 12篇 |
2020年 | 9篇 |
2019年 | 16篇 |
2018年 | 10篇 |
2017年 | 11篇 |
2016年 | 12篇 |
2015年 | 5篇 |
2014年 | 31篇 |
2013年 | 66篇 |
2012年 | 49篇 |
2011年 | 57篇 |
2010年 | 57篇 |
2009年 | 60篇 |
2008年 | 51篇 |
2007年 | 48篇 |
2006年 | 51篇 |
2005年 | 50篇 |
2004年 | 30篇 |
2003年 | 35篇 |
2002年 | 37篇 |
2001年 | 15篇 |
2000年 | 14篇 |
1999年 | 29篇 |
1998年 | 27篇 |
1997年 | 21篇 |
1996年 | 22篇 |
1995年 | 25篇 |
1994年 | 22篇 |
1993年 | 9篇 |
1992年 | 18篇 |
1991年 | 11篇 |
1990年 | 9篇 |
1989年 | 10篇 |
1988年 | 12篇 |
1987年 | 13篇 |
1986年 | 9篇 |
1985年 | 10篇 |
1984年 | 12篇 |
1983年 | 9篇 |
1982年 | 12篇 |
1981年 | 16篇 |
1980年 | 14篇 |
1979年 | 7篇 |
1977年 | 5篇 |
1976年 | 10篇 |
1975年 | 6篇 |
1974年 | 7篇 |
1971年 | 5篇 |
排序方式: 共有1104条查询结果,搜索用时 15 毫秒
141.
142.
Measurements have been made of the length changes due to self-irradiation damage at 4.2 K for over 1300 h in a U-Pu-Mo bcc alloy (containing 20 at% plutonium and 15 at% molybdenum) stabilized by quenching. These are the first measurements of this type carried out on a bcc alloy. The initial rate of increase of δl/l was If it is assumed that each α desintegration forms 1800 Frenkel pairs, it is found that Frenkel pairs have a formation volume equal to 0.5 atomic volume. 相似文献
143.
144.
Jean-Pierre Bastide Bernard Bonnetot Jean-Marie Létoffé Pierre Claudy 《Materials Research Bulletin》1980,15(12):1779-1787
The structural relationships in magnesium hydride have been studied under P-T conditions up to 80 kbar and 900°C. α-MgH2 of rutile structure in normal conditions transforms into two new phases under high pressures : β-MgH2 and γ-MgH2 respectively with a hexagonal (pseudocubic) and an orthorhombic unit-cell structure·β-MgH2 maybe related to a fluorite type form (with an eight-coordination for Mg) transforming when releasing pressure into γ-MgH2 of α-PbO2 type (with a six-coordination for Mg). The density of α-MgH2 and γ-MgH2 are very similar but the density of the β-MgH2 fluorite form is some 25 % greater than that of the rutile type. Thus MgH2 seems to exhibit under high pressure conditions the typical behavior of number of rutile type compounds MX2 such as fluorides or oxides. 相似文献
145.
146.
Jean-Pierre Bonnet Jean-Claude Grenier Marc Onillon Michel Pouchard Paul Hagenmuller 《Materials Research Bulletin》1979,14(1):67-75
The type of point defects in non-stoichiometric Ca2LaFe3O8+x ferrite has been studied by measuring the variation of electrical conductivity with oxygen partial pressure at various temperatures. Several ordering possibilities occur. The oxygen atoms inserted, mostly 1-charged, have a strong tendency to couple at sufficient oxygen pressure and at low temperature. Interstitial oxygen atoms in the lattice vacancies induce structural evolution as non-stoichiometry becomes significant enough. 相似文献
147.
Quinton L Le Caer JP Phan G Ligny-Lemaire C Bourdais-Jomaron J Ducancel F Chamot-Rooke J 《Analytical chemistry》2005,77(20):6630-6639
The standard analytical procedure for screening the proteomic profile of a venom often relies on an appropriate combination of sample extraction, electrophoresis, reversed-phase high-performance liquid chromatography, mass spectrometry, and Edman degradation. We present in this study a new approach for venom screening based on Fourier transform mass spectrometry (FTMS) analysis directly on the crude venom. The venom chosen is a unique sample from Atractaspis irregularis, a species never studied at the molecular level previously. This snake belongs to the Atractaspidae family that is known to produce highly toxic venoms containing endothelin-like peptides called sarafotoxins (SRTXs). Nanoelectrospray-FTMS spectrum of the crude venom allowed the identification of 60 distinct compounds with molecular masses from 600 to 14,000 Da, which would have been impossible without the resolution of this kind of instrument. De novo sequencing within the entire venom confirmed the sequences of two new families of sarafotoxins, whose precursors had been cloned, and allowed the characterization of a third one. One particularly interesting point was that the propolypeptides appeared processed not in one unique compound, but rather in different length molecules ranging from 15 for the shorter to 30 amino acids for the longer. Moreover, our results clearly establish that in the case of A. irregularis only one copy of mature sarafotoxin emerges from each precursor, which is a totally different organization in comparison of other precursors of SRTXs. 相似文献
148.
149.
Projection of transmembrane helices using a Uniform B-spline Algorithm is a tool for the visualization of interactions between helices in membrane proteins. It allows the user to generate projections of 3D helices, no matter what their deviations from a canonical helix might be. When associated with adapted coloring schemes it facilitates the comprehension of helix-helix interactions. Examples of transmembrane proteins were chosen to illustrate the advantages that this method provides. In the glycophorin A dimer we can easily appreciate the structural features behind homodimerisation. Using the structure of the fumarate reductase we analyze the contact surfaces inside a helical bundle and thanks to structures from a molecular dynamics simulation we see how modifications in structure and electrostatics relate to their interaction. We propose the use of this tool as an aid to the visualization and analysis of transmembrane helix surfaces and properties. 相似文献
150.
Jean-Michel Lucas Philippe Berticat Bernard Chabert Jean-Pierre Soulier Louis Gavet Noëlle Valentin 《大分子材料与工程》1977,65(1):103-120
Sizing is generally employed to protect yarns when submitted to mechanical stress during weaving. Two commercial acrylic copolymers used for sizing of polyester yarns are studied: an acrylonitril-acrylic acid copolymer (A) as a bad sizing product and an acrylonitril-acrylic acid-ethyl acrylate copolymer (B) as a good one. A relationship has been established between physico-chemical parameters and sizing efficiency. Interactions between polyester yarn and size (and samples used as models) are studied both in solution and in dry state. It must be pointed out that the action of water is basically due to its plasticizing properties. The presence of ethyl acrylate favorizes the polyester yarn impregnation with size B in aqueous solution. Adhesion in the dry state is mainly caused by acrylic acid. Finally the action of neutralizing agents and imbeding oils is discussed. 相似文献