全文获取类型
收费全文 | 7808篇 |
免费 | 367篇 |
国内免费 | 15篇 |
专业分类
电工技术 | 159篇 |
综合类 | 21篇 |
化学工业 | 1525篇 |
金属工艺 | 218篇 |
机械仪表 | 402篇 |
建筑科学 | 170篇 |
矿业工程 | 5篇 |
能源动力 | 297篇 |
轻工业 | 605篇 |
水利工程 | 42篇 |
石油天然气 | 21篇 |
无线电 | 1457篇 |
一般工业技术 | 1357篇 |
冶金工业 | 720篇 |
原子能技术 | 89篇 |
自动化技术 | 1102篇 |
出版年
2023年 | 61篇 |
2022年 | 86篇 |
2021年 | 126篇 |
2020年 | 110篇 |
2019年 | 129篇 |
2018年 | 167篇 |
2017年 | 146篇 |
2016年 | 214篇 |
2015年 | 187篇 |
2014年 | 311篇 |
2013年 | 544篇 |
2012年 | 443篇 |
2011年 | 481篇 |
2010年 | 351篇 |
2009年 | 426篇 |
2008年 | 364篇 |
2007年 | 332篇 |
2006年 | 335篇 |
2005年 | 288篇 |
2004年 | 274篇 |
2003年 | 251篇 |
2002年 | 277篇 |
2001年 | 206篇 |
2000年 | 186篇 |
1999年 | 176篇 |
1998年 | 375篇 |
1997年 | 221篇 |
1996年 | 162篇 |
1995年 | 133篇 |
1994年 | 114篇 |
1993年 | 114篇 |
1992年 | 60篇 |
1991年 | 71篇 |
1990年 | 56篇 |
1989年 | 58篇 |
1988年 | 40篇 |
1987年 | 44篇 |
1986年 | 39篇 |
1985年 | 31篇 |
1984年 | 29篇 |
1983年 | 20篇 |
1982年 | 14篇 |
1981年 | 23篇 |
1980年 | 16篇 |
1979年 | 9篇 |
1978年 | 15篇 |
1977年 | 14篇 |
1976年 | 21篇 |
1974年 | 6篇 |
1973年 | 8篇 |
排序方式: 共有8190条查询结果,搜索用时 0 毫秒
91.
Jae Kyeong Jeong Jong Han Jeong Hui Won Yang Tae Kyung Ahn Minkyu Kim Kwang Suk Kim Bon Seog Gu Hyun‐Joong Chung Jin‐Seong Park Yeon‐Gon Mo Hye Dong Kim Ho Kyoon Chung 《Journal of the Society for Information Display》2009,17(2):95-100
Abstract— A full‐color 12.1‐in.WXGA active‐matrix organic‐light‐emitting‐diode (AMOLED) display was, for the first time, demonstrated using indium‐gallium‐zinc oxide (IGZO) thin‐film transistors (TFTs) as an active‐matrix backplane. It was found that the fabricated AMOLED display did not suffer from the well‐known pixel non‐uniformity in luminance, even though the simple structure consisting of two transistors and one capacitor was adopted as the unit pixel circuit, which was attributed to the amorphous nature of IGZO semiconductors. The n‐channel a‐IGZO TFTs exhibited a field‐effect mobility of 17 cm2/V‐sec, threshold voltage of 1.1 V, on/off ratio >109, and subthreshold gate swing of 0.28 V/dec. The AMOLED display with a‐IGZO TFT array is promising for large‐sized applications such as notebook PCs and HDTVs because the a‐IGZO semiconductor can be deposited on large glass substrates (larger than Gen 7) using the conventional sputtering system. 相似文献
92.
In this paper, we review the state-of-the-art in surface-enhanced Raman scattering (SERS) based optical detection techniques
with an application focus on cancer diagnostics. As we describe herein, SERS has several analytical, biological and engineering
advantages over other methods including extremely high sensitivity, inherent molecular specificity of unlabeled targets, and
narrow spectral bands. We review advances in both in vitro and in vivo applications of SERS and examine how technical issues
with the technology are being addressed. A special technology focus is given to emerging optofluidic devices which aim to
merge microfluidic and optical detection technologies into simple packages. We conclude with a brief discussion of some of
the emerging challenges in the field and some of the approaches that are likely to enhance their application.
Y. S. Huh and A. J. Chung contributed equally. 相似文献
93.
3-D manipulation of millimeter- and micro-sized objects using an acoustically excited oscillating bubble 总被引:1,自引:1,他引:0
This communication describes novel 3-D manipulations of objects using an acoustically excited oscillating bubble deposited
on a hydrophobic rod tip. The oscillating bubble captures various millimeter- and micron-sized neighboring objects including
glass and polystyrene beads (~100 μm), fish egg, and live water flea (~1 mm). The captured objects are carried in a 3-D space
by traversing the bubble tip, and released at desired positions by simply turning off the oscillation. Carrying performance
is characterized along with high-speed imaging of oscillating bubbles by varying the frequency and amplitude of the acoustic
excitation and the carrying speed. The higher the oscillation amplitude, the higher the carrying efficiency. The maximum carrying
speed is measured at over 3 mm/s. This method is effective with a low-level acoustic excitation (bubble oscillation amplitude
relative to the diameter ≤5%), possibly providing a cost-effective, soft-contact manipulating tool for handling biological
objects. 相似文献
94.
In order to effectively pump liquid in a fluidic chip, the PDMS or SU8 channels were frequently modified by surface treatments
to obtain the hydrophilic surface but encountered the problem of the hydrophobic recovery. In this article, long-term highly
hydrophilic fluidic chips were demonstrated using rapid fabrication of low-power CO2 laser ablation and low-temperature glass bonding with an interlayer of liquid crystal polymer (LCP). The intrinsic hydrophilic
materials of glass and LCP were beneficial for self-driven flow in the long-term fluidic chip by surface-tension force with
no extra fluidic pumps. The higher viscosity fluid could increase the difficulty of self-driven capability. The stability
of contact angle and flow test of the chip after 2 months is similar to that at beginning. The high-viscosity human whole
blood was successfully driven at an average moving velocity of about 1.89 mm/s for the beginning and at 2.04 mm/s after 2 months.
Our fluidic chip simplifies the traditional complex fabrication procedure of glass chips and conquers the problem of traditional
hydrophobic recovery. 相似文献
95.
In this article, the method for increasing dynamic stability of quadruped robot is proposed. Previous researches on dynamic
walking of quadruped robots have used only walking pattern called central pattern generator (CPG). In this research, different
from walking generation with only CPG, a instinctive stability measure called landing accordance ratio, is proposed and used
for increasing dynamic stability. In addition, dynamic balance control and control to adjust walking trajectory for increasing
dynamic stability measure is also proposed. Proposed methods are verified with dynamic simulation and a large number of experiments
with quadruped robot platform. 相似文献
96.
The reaction between silicon carbide and aluminium to form silicon and Al4C3 in SiC particle-reinforced aluminium fabricated by liquid aluminium infiltration was most severe near the original interface between liquid aluminium and the SiC preform. This resulted in the highest concentration of Al4C3 and the lowest concentrations of silicon and SiC in the part of the composite near this interface. In particular, the silicon concentration was highest in the bottom centre of the composite when infiltration occurred from the top, because silicon diffused toward the surrounding aluminium melt before solidification. These non-uniform phase distributions, as measured by X-ray diffraction and differential scanning calorimetry, did not cause any non-uniform shear strength distribution. However, excessive reaction between SiC and aluminium, as observed for an infiltration (=mould=liquid metal) temperature of 780° C, caused the tensile strength to decrease. In the case where a steel mould was used during infiltration at 780° C, iron-containing precipitates, such as ternary Al-Fe-Si, were observed in the part of the composite within 5 mm from the above-mentioned interface; their formation was related to the silicon out-diffusion in the form of liquid Al-Si; they caused the shear strength to be lower in this part of the composite; larger such precipitates (up to 100 m) were observed in the excess aluminium adjacent to the cast composite. For pure aluminium as the infiltrating metal, the optimum infiltration temperature for the highest tensile strength was 700° C. An infiltration temperature of 670° C resulted in incomplete infiltration, which was more severe when a steel mould rather than a graphite mould was used because of the higher thermal conductivity of the former. 相似文献
97.
Supervisory control using variable lookahead policies 总被引:1,自引:1,他引:0
This paper deals with the efficient on-line calculation of supervisory controls for discrete event systems (DES's) in the framework of limited lookahead control policies (or LLPs) that we introduced in previous papers. In the LLP scheme, the control action after a given trace of events has been executed is calculated on-line on the basis of anN-step ahead projection of the behavior of the DES. To compute these controls, one must calculate after the execution of each event the supremal controllable sublanguage of a finite language with respect to another finite larger language. In our previous work, we showed how the required supremal controllable sublanguage calculation can be performed by using a backward dynamic programming algorithm over the nodes of the tree representation of these two languages. In this paper, we pursue the same approach for the calculation of LLP controls, but instead we adopt a forward calculation procedure over theN-level tree of interest. This forward procedure improves upon previous work by avoiding the explicit consideration of all the nodes of theN-level tree, while still permitting tree-to-tree recursiveness as enabled events are executed by the system. The forward search ends whenever a control decision can be made unambiguously or whenever the boundary of theN-level tree is reached, whichever comes first. This motivates the name Variable Lookahead Policy (or VLP) for this implementation of the LLP supervisory control scheme. This paper presents a general VLP algorithm and studies the properties of several special cases of it. The paper also discusses the implementation of the VLP algorithms and presents computational results regarding the application of these algorithms to a time-varying DES. 相似文献
98.
Effects of the thermally grown wustite on the fatigue crack initiation and growth in HSLA steel are evaluated as a function of oxide thickness, strain amplitude, and gaseous environment in the push-pull plastic strain control mode, with special attention being given to the early stage of microcrack initiation. Specimens with a wustite surface layer thermally grown to 0.2 and 0.6 m thicknesses show predominantly intergranular cracking at plastic strain amplitudes of 5×10–4 and 1×10–3 both in air and in ultrahigh vacuum (UHV), in contrast to the as-polished specimens where slip band cracking is the favoured mode. The cracking mode in the oxide layer is discussed in terms of the strain amplitude and the dislocation behaviour near the oxide/metal interface. The features of microcrack initiation in the oxide layer is not affected by the gaseous environment. Once, however, the surface oxide fractures, the rate of crack growth through the base metal is greatly reduced in UHV. 相似文献
99.
Aluminium nitride substrates were immersed in acid, basic solutions and deionized water for 1–120 h at room temperature. The corrosion rates are higher in basic solutions (NaOH and KOH) than those in acid solutions (CH3COOH, HCOOH, HNO3, HCl and H2SO4) and deionized water. The weight loss of AIN corroded in alkali aqueous reaches 70% and results in an increase in surface roughness ranging from 10 nm to 7 m after 3 days corrosion. However, the weight loss in acid solution is only 1/700 of the alkali case. Violent chemical reactions between AIN and basic solutions were observed. Na2O, or Na2Al2O4·6H2O, is the intermediate product, and NaOH is a catalytic agent of the reaction. The surface morphology of the AIN etched by alkaline solutions is coral-like in microscopic view and appears like hills. In contrast, only several atomic layers of AIN surface are etched off in acid solutions and in deionized water. The lightly etched surface is mirror-like and flat, and the shapes of the grains are visible under the microscope, as the corrosion rate of each AIN grain varies with different crystal orientations. Consequently, after etching in acid solutions, the resulting microscopic surface morphology looks like a map of a jigsaw puzzle. 相似文献
100.
Changmin Lee Youngjae Hong Dongho Kim Younghwan Lim Jang Wook Choi Sung-Yoon Chung 《Advanced functional materials》2023,33(44):2303763
Protons in aqueous electrolytes can perform as an additional type of charge carrier for insertion/extraction in addition to the primary carrier cations in aqueous rechargeable batteries. Despite many diverse claims regarding the effect of protons, mutually conflicting experimental results and their interpretations without direct evidence have been reported over the last decade. Systematic examinations and analyses are thus imperative to clarify the conditions of proton insertion in aqueous rechargeable batteries. Utilizing V2O5 as a model cathode and beaker-type cells with a sufficient amount of ZnSO4 aqueous electrolytes in this work, it is demonstrated that protons are inserted into the cathode prior to Zn-ions in low-pH conditions (pH ≤ 3.0). In stark contrast, the influence of protons on the discharge voltage and capacity is insignificant, when either the pH becomes higher (pH ≥ 4.0) or the electrolyte volume is considerably low in coin-type cells. Similar behavior of pH-dependent proton insertion is also verified in Na–, Mg–, and Al-ion electrolytes. Providing a resolution to the controversy regarding proton insertion, the present study emphasizes that the influence of protons substantially varies depending on the pH and relative volume of electrolytes in aqueous batteries. 相似文献