全文获取类型
收费全文 | 1082篇 |
免费 | 25篇 |
专业分类
电工技术 | 19篇 |
化学工业 | 238篇 |
金属工艺 | 27篇 |
机械仪表 | 22篇 |
建筑科学 | 57篇 |
矿业工程 | 23篇 |
能源动力 | 14篇 |
轻工业 | 111篇 |
水利工程 | 21篇 |
石油天然气 | 3篇 |
无线电 | 75篇 |
一般工业技术 | 189篇 |
冶金工业 | 152篇 |
原子能技术 | 8篇 |
自动化技术 | 148篇 |
出版年
2022年 | 17篇 |
2021年 | 18篇 |
2020年 | 18篇 |
2019年 | 11篇 |
2018年 | 12篇 |
2017年 | 11篇 |
2016年 | 25篇 |
2015年 | 19篇 |
2014年 | 32篇 |
2013年 | 49篇 |
2012年 | 56篇 |
2011年 | 64篇 |
2010年 | 49篇 |
2009年 | 46篇 |
2008年 | 50篇 |
2007年 | 49篇 |
2006年 | 34篇 |
2005年 | 31篇 |
2004年 | 33篇 |
2003年 | 24篇 |
2002年 | 33篇 |
2001年 | 14篇 |
2000年 | 24篇 |
1999年 | 24篇 |
1998年 | 27篇 |
1997年 | 26篇 |
1996年 | 14篇 |
1995年 | 15篇 |
1994年 | 15篇 |
1993年 | 12篇 |
1992年 | 13篇 |
1991年 | 15篇 |
1990年 | 9篇 |
1989年 | 7篇 |
1988年 | 15篇 |
1987年 | 20篇 |
1986年 | 7篇 |
1985年 | 11篇 |
1984年 | 11篇 |
1983年 | 12篇 |
1982年 | 10篇 |
1981年 | 7篇 |
1980年 | 8篇 |
1979年 | 9篇 |
1978年 | 8篇 |
1977年 | 12篇 |
1975年 | 10篇 |
1972年 | 8篇 |
1971年 | 6篇 |
1970年 | 7篇 |
排序方式: 共有1107条查询结果,搜索用时 15 毫秒
81.
Hubert Laitko 《NTM》1999,7(1):118-119
Ohne Zusammenfassung 相似文献
82.
L. A. J. Garvie H. Hubert P. Rez P. F. McMillan P. R. Buseck 《Journal of Alloys and Compounds》1999,290(1-2)
Hexagonal boron nitride (hex BN) containing significant amounts of C and O substituting for N (hex BCNO) was synthesized at 75 kbar and 1700°C from mixtures of C, B2O3, and amorphous B contained in a hex BN crucible. Hex BCNO is a minor constituent of the product and occurs as small, <30 nm diameter, rounded pseudohexagonal particles adhering to materials with the α-rhombohedral B structure. Electron energy-loss spectroscopy with a transmission electron microscope was used to quantify their elemental ratios. Up to 50% of the N in hex BN is replaced by C and O, e.g., BN0.49O0.38C0.11. The electron energy-loss near-edge fine structure of the core-loss edges was used to elucidate the possible structures of hex BCNO. The core-loss edges of B, C, N, and O exhibit orientation-dependent intensity changes, which indicates that they occupy similar anisotropic bonding sites in graphite-like BCNO layers. For a composition of BN0.5O0.4C0.1, regions with B–N3, B–N2O, and B–NO2 units predominate. In addition, some grains have significant quantities of B–O3 and B–C3 units. Boron–boron bonding is either absent or infrequent. 相似文献
83.
Out-of-autoclave prepregs based on woven fabrics initially consist of dry tows and resin-rich areas. The tows allow air evacuation in the initial stages of processing and are subsequently infiltrated by surrounding matrix. The following study analyzes the relationship between material properties, process parameters and tow impregnation for three OOA prepregs. First, a representative model for tow impregnation is developed. Then, the model parameters are determined and the model predictions are correlated to impregnation data measured by X-ray microtomography. Finally, the model is used in a parametric study to investigate the effect of fibre architecture, cure cycle temperature and resin initial degree of cure on tow impregnation rate and to predict the possible occurrence of flow-induced micro-voids. 相似文献
84.
Allaoua Achouri Joyce Irene Boye Denis Belanger Tiphaine Chiron Varoujan A. Yaylayan Faustinus K. Yeboah 《Food research international (Ottawa, Ont.)》2010,43(5):1494-1504
This study describes an extraction process for the preparation of highly purified calcium precipitated glycinin (11S). Initial extraction of soy proteins using isoelectric precipitation at pH 6.8 followed by cryo-precipitation yielded 4.2% product (11S) recovery with 98% protein purity for the control extracted with NaOH. Addition of calcium chloride (CaCl2) doubled the extraction yield (9%) compared to the control and when two other salts were used (i.e., sodium (Na2SO4) and ammonium (NH4)2SO4 sulfate, average yields of 4.4% and 5.17%, respectively). Thermal and molecular stability under varying conditions (pH, salts, SDS as a protein structure perturbing agent), and effect of glycation on functional and structural properties were investigated. Size exclusion chromatography and electrophoresis confirmed the predominance of a major band with MW of ~342 kDa with 98.4% purity. Differential scanning calorimetry (DSC) yielded one endothermic transition peak at 95.5 °C. Denaturation temperatures were >100 °C for all salt concentrations studied. The pH had a dominant influence on the structural properties of glycinin. In the presence of NaCl and CaCl2 (0.2–1 M), the protein structure showed very little denaturation and no aggregation bands were observed even on heating to 95 °C. Lower SDS concentrations (0.5–1%) resulted in denaturation and aggregation, while at 2% SDS only denaturation was observed. Glycation did not alter the conformational structure of protein. Improvements in surface properties were observed with moderate degree of glycation (6–24 h). 相似文献
85.
Yang K. Marshall T. Forman M. Hubert J. Mirth L. Popovic Z. Katehi L.P.B. Whitaker J.F. 《Microwave Theory and Techniques》2001,49(5):849-857
Several Ka-band spatial-amplifier power combiners and their free-space feeds were characterized using a high-resolution extreme-near-field electrooptic measurement technique. The two-dimensional electric-field amplitude and phase maps obtained from several arrays are presented. The usefulness of the technique for diagnostic purposes during the design and prototyping stages of the active arrays is discussed. In particular, the electrooptic maps were shown to be valuable for making improvements in the bias line design in one case, and for isolating faulty unit cells in another case 相似文献
86.
87.
The “imponderables” which affect the framework within which the Plating Shop must be planned are listed. The grouping of vats, cleaners and rinses are discussed and alternative methods of hand operation of plating vats described. The importance of depth of plating vats is stressed and various methods of constructing floors, drainage and vat supports are briefly indicated. Layouts for barrel plating shops both with inclined and horizontal barrels are suggested, and the importance of correct housing for electrical and other ancillary plant is emphasised. 相似文献
88.
Hubert Cachet 《Electrochimica acta》2010,55(21):6233-10370
Macromolecules like proteins are able to adhere to tin oxide electrodes at open circuit potential as proved by electrogravimetry experiments. In this work, electrochemical impedance studies were performed at aqueous electrolyte/F- or Sb-doped semiconducting tin oxide interfaces, including natural seawater. By this way, it was possible to characterize the potential dependence of the interfacial capacitance in various physicochemical conditions, without or in the presence of bovine serum albumin (BSA). In the potential range where tin oxide is in the depletion regime (blocking interface), a capacitance excess is evidenced which can be attributed to the formation of surface states which are the signature of chemical bonding. By simulating the so-called surface state capacitance, three states have been pointed out. They are centred at 0.7, 0.9 and 1.1 eV in the tin oxide bandgap. On the basis of experimental arguments, the state at 1.1 eV was ascribed to the OH-terminated tin oxide surface, the two other states were found to be specific of the interaction of organic matter with the oxide surface. In the presence of BSA, the density of surface atoms (about 1013 cm−2) involved in bonding is of the order of magnitude of the surface concentration of one BSA monolayer. The lasting character of these bonds was also shown. This finding shows the definitive protein immobilisation at the SnO2 surface. 相似文献
89.
The world is not flat: from field ion microscopy to atom probe tomography Atom probe tomography has gained considerable importance in the past couple of years due to the steadily increasing demands on the capabilities of analytical tools for nanotechnology. Presently available preparation and instrumental methods allow the application of atom probe tomography also for technically relevant specimens. This affords a unique analytical approach for a quantitative and highly sensitive characterization of the chemical content of materials; by combining these features with the three dimensional registration of the elemental distributions, atomic spatial resolution can be achieved both laterally and in‐depth. For this reason, atom probe tomography is very well suited for the determination of the composition and morphology of crystalline and amorphous materials and nanostructures, and may have an enormous impact on research and development in various areas of material sciences. The first part of this contribution on modern atom probe tomography illustrates the evolution of the technique from its beginnings in the 1950s to the presently available commercial instruments. In the course of this overview, the basic physical and instrumental concepts will briefly be outlined. The second part will concentrate on the presentation of selected, current applications; these examples will serve also to emphasize some of the limitations of atom probe tomography. 相似文献