全文获取类型
收费全文 | 959篇 |
免费 | 6篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 13篇 |
综合类 | 1篇 |
化学工业 | 110篇 |
金属工艺 | 8篇 |
机械仪表 | 17篇 |
建筑科学 | 21篇 |
矿业工程 | 1篇 |
能源动力 | 22篇 |
轻工业 | 56篇 |
水利工程 | 1篇 |
石油天然气 | 2篇 |
无线电 | 125篇 |
一般工业技术 | 177篇 |
冶金工业 | 232篇 |
原子能技术 | 6篇 |
自动化技术 | 174篇 |
出版年
2023年 | 10篇 |
2022年 | 14篇 |
2021年 | 19篇 |
2020年 | 12篇 |
2019年 | 22篇 |
2018年 | 18篇 |
2017年 | 14篇 |
2016年 | 29篇 |
2015年 | 13篇 |
2014年 | 21篇 |
2013年 | 39篇 |
2012年 | 22篇 |
2011年 | 51篇 |
2010年 | 26篇 |
2009年 | 25篇 |
2008年 | 32篇 |
2007年 | 37篇 |
2006年 | 35篇 |
2005年 | 24篇 |
2004年 | 23篇 |
2003年 | 25篇 |
2002年 | 34篇 |
2001年 | 15篇 |
2000年 | 18篇 |
1999年 | 22篇 |
1998年 | 61篇 |
1997年 | 45篇 |
1996年 | 34篇 |
1995年 | 20篇 |
1994年 | 22篇 |
1993年 | 29篇 |
1992年 | 10篇 |
1991年 | 8篇 |
1990年 | 10篇 |
1989年 | 11篇 |
1988年 | 10篇 |
1986年 | 8篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1977年 | 6篇 |
1976年 | 7篇 |
1975年 | 6篇 |
1974年 | 5篇 |
1973年 | 7篇 |
1971年 | 3篇 |
1969年 | 5篇 |
排序方式: 共有966条查询结果,搜索用时 15 毫秒
91.
Flavio Abreu Araujo Tristan da Cmara Santa Clara Gomes Luc Piraux 《Advanced Electronic Materials》2019,5(8)
Spin‐related effects in thermoelectricity can be used to design more efficient refrigerators and offer promising applications for the harvesting of thermal energy. The key challenge is to design structural and compositional magnetic material systems with sufficiently high efficiency and power output for transforming thermal energy into electric energy and vice versa. The fabrication of large‐area 3D interconnected Co/Cu nanowire networks is demonstrated, thereby enabling the controlled Peltier cooling of macroscopic electronic components with an external magnetic field. The flexible, macroscopic devices overcome the inherent limitations of nanoscale magnetic structures that are caused by insufficient power generation capability limiting the heat management applications. From properly designed experiments, large spin‐dependent Seebeck and Peltier coefficients of −9.4 µV K−1 and −2.8 mV at room temperature, respectively, are found. The resulting power factor of Co/Cu nanowire networks at room temperature (≈ 7.5 mW K−2 m−1) is larger than those of state‐of‐the‐art thermoelectric materials, such as BiTe alloys, and the magnetopower factor ratio reaches about 100% over a wide temperature range. Validation of magnetic control of heat flow achieved by taking advantage of the spin‐dependent thermoelectric properties of flexible macroscopic nanowire networks lays the groundwork to design shapeable thermoelectric coolers exploiting the spin degree of freedom. 相似文献
92.
Flavio Y. Bruno Siobhan McKeown Walker Sara Ricc Alberto de la Torre Zhiming Wang Anna Tamai Timur K. Kim Moritz Hoesch Mohammad S. Bahramy Felix Baumberger 《Advanced Electronic Materials》2019,5(5)
2D electron gases (2DEGs) in oxides show great potential for the discovery of new physical phenomena and at the same time hold promise for electronic applications. In this work, angle‐resolved photoemission is used to determine the electronic structure of a 2DEG stabilized in the (111)‐oriented surface of the strong spin–orbit coupling material KTaO3. The measurements reveal multiple sub‐bands that emerge as a consequence of quantum confinement and form a sixfold symmetric Fermi surface. This electronic structure is well reproduced by self‐consistent tight‐binding supercell calculations. Based on these calculations, the spin and orbital texture of the 2DEG is determined. It is found that the 2DEG Fermi surface is derived from bulk J = 3/2 states and exhibits an unconventional anisotropic Rashba‐like lifting of the spin‐degeneracy. Spin‐momentum locking holds only for high‐symmetry directions and a strong out‐of‐plane spin component renders the spin texture threefold symmetric. It is found that the average spin‐splitting on the Fermi surface is an order of magnitude larger than in SrTiO3, which should translate into an enhancement in the spin–orbitronic response of (111)‐KTaO3 2DEG‐based devices. 相似文献
93.
Francesco Massa Amir Moqanaki min Baumeler Flavio Del Santo Joshua A. Kettlewell Borivoje Daki Philip Walther 《Advanced Quantum Technologies》2019,2(11)
Superposition of two or more states is one of the most fundamental concepts of quantum mechanics and provides a basis for several advantages offered by quantum information processing. This work reports the experimental demonstration of two‐way communication between two distant parties that can exchange only a single particle once, an impossible task in classical physics. This is achieved through preparation of a single photon in a coherent superposition of the two parties' locations. Furthermore, it is shown that this concept allows the parties to perform secure and anonymous quantum communication employing one particle per transmitted bit. These important features can lead to the realization of new quantum communication schemes, which are simultaneously anonymous, secure, and resource‐efficient. 相似文献
94.
Salvatore Ventre Flavio Calvano Grégoire Pichenot Pierre Calmon Antonello Tamburrino 《NDT & E International》2011,44(4):376-386
This paper is focused on the Eddy Current Testing (ECT) method applied to important industrial applications such as the inspection of tubes in nuclear power plants and the inspection of planar surface from aeronautical industry. Specifically, we consider the prediction of the signatures produced by small defects through two fully three-dimensional numerical models developed for ECT. In particular we consider the responses to small defects described in two experimental benchmarks from nuclear power industry and one experimental benchmark from aeronautical applications. Despite of the small size of the defects that, in some cases, is of the order of few millimetres, the numerical models reproduce correctly the experimental responses provided in the benchmarks, including the challenging case of a defect (in a tube) close to the support plate. 相似文献
95.
Mohammad Masoumi Cleiton Carvalho Silva Igor Anjos Lemos Luis Flavio Gaspar Herculano Hamilton Ferreira Gomes de Abreu 《Journal of Materials Engineering and Performance》2017,26(4):1531-1539
The microstructural and textural evolution was analyzed during rolling at room temperature to obtain detailed information about the failure behavior in HSLA grade-420 steel. Electron backscatter diffraction measurements were carried out in both non-cracked and cracked areas after cold rolling to find a correlation between microstructural parameters (i.e., grain orientation, grain boundary characteristics and Taylor factor) and crack propagation. The results showed that the crack tended to propagate along grains oriented with {001} planes parallel to the normal direction with high Taylor factor value. The special boundaries associated with the {111}, {110} and {221} planes were indicated as crack resistance, while ∑ 5, 13a and 17a, which related to the {001} planes, were crack-susceptible. Transgranular cracking was subjected within grains with high Taylor factor, while mismatch in Taylor factor between neighboring grains could provide an easy path for intergranular crack propagation. 相似文献
96.
Pedersoli E Capotondi F Cocco D Zangrando M Kaulich B Menk RH Locatelli A Mentes TO Spezzani C Sandrin G Bacescu DM Kiskinova M Bajt S Barthelmess M Barty A Schulz J Gumprecht L Chapman HN Nelson AJ Frank M Pivovaroff MJ Woods BW Bogan MJ Hajdu J 《The Review of scientific instruments》2011,82(4):043711
We present a compact modular apparatus with a flexible design that will be operated at the DiProI beamline of the Fermi@Elettra free electron laser (FEL) for performing static and time-resolved coherent diffraction imaging experiments, taking advantage of the full coherence and variable polarization of the short seeded FEL pulses. The apparatus has been assembled and the potential of the experimental setup is demonstrated by commissioning tests with coherent synchrotron radiation. This multipurpose experimental station will be open to general users after installation at the Fermi@Elettra free electron laser in 2011. 相似文献
97.
98.
A dimensionless methodology to evaluate the water saving obtainable from large-scale implementation of domestic rain water harvesting (RWH) systems in urban areas is presented. The methodology combines the use of regressive relationships for water saving evaluation based on the results of the dimensionless rainwater tank water balance and of catchment-wide information obtained from geospatial databases. The adopted RWH scheme included internal use of rainwater for toilet flushing and external use for garden irrigation. An application to a portion of the city of Rome, Italy showed the methodology to allow systematic and accurate evaluation of RWH system performance at the selected urban scale. Results pointed out high water saving potential for toilet flushing ranging between 38–65% for tank sizes within 1–50 m3. Furthermore, more than one third of the systems provided water saving benefit for irrigation larger than 20% by using a 50 m3 tank. 相似文献
99.
This paper describes the behaviour under cyclic shear compression of an innovative reinforced masonry system, composed of horizontally perforated units, having common steel bars or prefabricated trusses as horizontal reinforcement. At the wall edges or crossings, confining columns for vertical reinforcement are built with vertically perforated units. Experimental tests to obtain information on the in-plane cyclic behaviour of the construction system were performed on masonry panels made of horizontally perforated units and on completed reinforced masonry walls. Tests on the entire system were repeated for two wall aspect ratios and two vertical stress levels, in order to force shear type and flexural behaviour. In particular, this paper presents: (a) results of shear compression tests in terms of strength, ductility parameters, energy dissipation, viscous damping and stiffness degradation, (b) strains and the effectiveness of reinforcement, (c) the influence of various parameters such as axial load, aspect ratio, and reinforcement type on the behaviour of the reinforced masonry walls, and (d) comparison of walls built with and without vertical reinforcement. 相似文献
100.
In 1991, the U.S. Geological Survey (USGS) began the first cycle of its National Water Quality Assessment (NAWQA) Program. The Program encompassed 51 river basins that collectively accounted for more than 70% of the total water use (excluding power generation), and 50% of the drinking water supply in the U.S. The basins represented a variety of hydrologic settings, rock types (geology), land-use categories, and population densities. One aspect of the first cycle included bed sediment sampling; sites were chosen to represent baseline and important land-use categories (e.g., agriculture, urban) in each basin. In total, over 1200 bed sediment samples were collected. All samples were size-limited (< 63 µm) to facilitate spatial and/or temporal comparisons, and subsequently analyzed for a variety of chemical constituents including major (e.g., Fe, Al,) and trace elements (e.g., Cu, Zn, Cd), nutrients (e.g., P), and carbon. The analyses yielded total (≥ 95% of the concentrations present), rather than total-recoverable chemical data.Land-use percentages, upstream underlying geology, and population density were determined for each site and evaluated to asses their relative influence on sediment chemistry. Baseline concentrations for the entire U.S. also were generated from a subset of all the samples, and are based on material collected from low population (≤ 27 p km− 2) density, low percent urban (≤ 5%), agricultural or undeveloped areas. The NAWQA baseline values are similar to those found in other national and global datasets. Further, it appears that upstream/underlying rock type has only a limited effect (mostly major elements) on sediment chemistry. The only land-use category that appears to substantially affect sediment chemistry is percent urban, and this result is mirrored by population density; in fact, the latter appears more consistent than the former. 相似文献