全文获取类型
收费全文 | 8872篇 |
免费 | 797篇 |
国内免费 | 16篇 |
专业分类
电工技术 | 121篇 |
综合类 | 15篇 |
化学工业 | 2148篇 |
金属工艺 | 350篇 |
机械仪表 | 431篇 |
建筑科学 | 135篇 |
矿业工程 | 3篇 |
能源动力 | 348篇 |
轻工业 | 915篇 |
水利工程 | 35篇 |
石油天然气 | 7篇 |
武器工业 | 1篇 |
无线电 | 1522篇 |
一般工业技术 | 2105篇 |
冶金工业 | 594篇 |
原子能技术 | 83篇 |
自动化技术 | 872篇 |
出版年
2024年 | 11篇 |
2023年 | 134篇 |
2022年 | 196篇 |
2021年 | 330篇 |
2020年 | 231篇 |
2019年 | 232篇 |
2018年 | 315篇 |
2017年 | 337篇 |
2016年 | 406篇 |
2015年 | 354篇 |
2014年 | 462篇 |
2013年 | 639篇 |
2012年 | 649篇 |
2011年 | 841篇 |
2010年 | 587篇 |
2009年 | 550篇 |
2008年 | 448篇 |
2007年 | 390篇 |
2006年 | 323篇 |
2005年 | 259篇 |
2004年 | 263篇 |
2003年 | 220篇 |
2002年 | 165篇 |
2001年 | 153篇 |
2000年 | 157篇 |
1999年 | 137篇 |
1998年 | 230篇 |
1997年 | 127篇 |
1996年 | 105篇 |
1995年 | 57篇 |
1994年 | 64篇 |
1993年 | 46篇 |
1992年 | 36篇 |
1991年 | 23篇 |
1990年 | 23篇 |
1989年 | 24篇 |
1988年 | 16篇 |
1987年 | 10篇 |
1986年 | 15篇 |
1985年 | 7篇 |
1984年 | 10篇 |
1983年 | 11篇 |
1981年 | 6篇 |
1980年 | 7篇 |
1979年 | 6篇 |
1977年 | 7篇 |
1976年 | 9篇 |
1974年 | 7篇 |
1971年 | 7篇 |
1970年 | 6篇 |
排序方式: 共有9685条查询结果,搜索用时 15 毫秒
131.
Yang-Il Jung Byoung-Ki Lee Suk-Joong L. Kang 《Journal of the American Ceramic Society》2004,87(4):739-741
A structural transition of Ba6 Ti17 O40 /BaTiO3 interfaces from faceted to rough was induced by reducing oxygen partial pressure in the atmosphere. As the oxygen partial pressure decreased, the number densities of {111} twins and abnormal grain decreased. TEM observation showed that the twin formation was governed only by the faceting of the interface. Experimental evidence of {111} twin-assisted abnormal growth of faceted BaTiO3 grains was also obtained. 相似文献
132.
Jae-Sang?ParkEmail author Young?Jung?Kee 《Journal of Mechanical Science and Technology》2015,29(8):3153-3163
This paper conducts the aeromechanics study using the two different rotorcraft computational structural dynamics (CSD) codes, CAMRAD II and DYMORE II, for the rotor in low-speed descending flight. The three test cases of the HART (Higher-harmonic control aeroacoustic rotor test) I -baseline, minimum noise, and minimum vibration- are considered in this study of the blade-vortex interaction (BVI) airloads, rotor trim, blade elastic deformations, and blade structural loads. The two prediction results are compared to each other for a code-to-code comparison study as well as to the measured data. Although CAMRAD II and DYMORE II use different theories and models, most of the prediction results are similar to each other and compared fairly well with the wind tunnel test data. For all the three test cases, the two rotorcraft CSD analyses show good prediction on the fluctuations of the section normal force (M2Cn) due to BVI, but both over-predict the trimmed collective pitch angle. The blade elastic deformations, such as flap deflection and elastic torsion deformation at the tip, are reasonably predicted by both rotorcraft CSD analyses. But, the CAMRAD II result using the multiple-trailer wake model with consolidation is slightly better than the DYMORE II prediction with the single wake panel model particularly for the elastic torsion deformation in the baseline case. In addition, CAMRAD II and DYMORE II both correlate reasonably the blade structural loads, such as flap bending, lead-lag bending, and torsion moments, with the measured data; however, the CAMRAD II results are moderately better than the DYMORE II predictions. 相似文献
133.
Junpeng Xue Zhongkai Yu Hyeon Mi Noh Jung Hyun Jeong Byung Chun Choi Sung Heum Park Bo Ram Lee Peng Du Mingjun Song 《Journal of the American Ceramic Society》2021,104(10):5086-5098
Ce3+/Tb3+ co-doped NaMgBO3 phosphors were successfully synthesized by solid-state method. Under 381 nm excitation, the cyan emission owing to the 5d → 4f of Ce3+ ions and green emissions arising from the 5D4 → 7FJ (J = 6, 5, 4, and 3) transitions of Tb3+ ions were seen in all the phosphors. Through theoretical analysis, one knows that the energy transfer from Ce3+ to Tb3+ ions with high efficiency of 83.74% was contributed by dipole–dipole transition. Furthermore, the internal quantum efficiency of NaMgBO3:0.01Ce3+,0.03Tb3+ phosphor was 54.28%. Compared with that of at 303 K, the emission intensity of the developed products at 423 K still kept 73%, revealing the splendid thermal stability of the studied phosphors. Through utilizing the resultant phosphors as cyan-green components, the fabricated white-LED device exhibited an excellent correlated color temperature of 2785 K, high color-rendering index of 85.73, suitable luminance efficiency of 25.00 lm/W, and appropriate color coordinate of (0.4279, 0.3617). Aside from the superior photoluminescence, the synthesized phosphors also exhibited excellent cathode-luminescence properties which were sensitive to the current and accelerating voltage. Furthermore, the NaMgBO3:0.01Ce3+,0.03Tb3+ phosphors with multi-mode emissions were promising candidates for optical anti-counterfeiting. All the results indicated that the Ce3+/Tb3+ co-doped NaMgBO3 phosphors were potential multi-platforms toward white-LED, field emission displays, and optical anti-counterfeiting applications. 相似文献
134.
Ahn Kyu-Hong Hwang Jong-Hyuk Song Kyung-Guen Jung Yong-Ho Cho Eul-Saeng Lim Byung-Ran Kim Kwang-Soo 《Metals and Materials International》2004,10(2):167-170
The performance of an attached growth wastewater treatment process was investigated in an effort to improve nitrogen removal
efficiency. Recycled Yakult (lactic acid fermentation drink) bottles made of polystyrene were used as a biofilm media. The
use of Yakult bottles as a biofilm media has been attempted by numerous researchers in Japan for the removal of solids and
organics. However, these studies focused only on the removal of solids and organics. This study extended their application
to the removal of nitrogen for domestic sewage treatment. Yakult media was placed in a reactor with 70% apparent reactor volume
in a conventional A/O process. The bottom of the Yakult media was removed, and randomly filled Yakult media were effectively
able to reduce the flow in tanks, resulting in an increase in the contact time between pollutants and microorganisms. With
higher HRT, the nitrogen removal efficiency was increased by up to 83% with 12 hr of HRT. Nitrification appeared to be the
limiting factor of nitrogen removal at an HRT that is less than 12 hr, indicating that the Yakult process requires more retention
time to achieve nitrification compared to other biofilm processes. The removal efficiencies of organics and solids were high
regardless of the change of operational parameters.
This article is based on a presentation in “The 7th Korea-China Workshop On Advanced Materials” organized by the Korea-China
Advanced Materials Cooperation Center and the China-Korea Advanced Materials Cooperation Center, held at Ramada Plaza Jeju
Hotel, Jeju Island, Korea on August 24–27, 2003. 相似文献
135.
Sang Chul Seo Hyun Jung Kim Byung Ho Park Kwang Suk Son Sung Keun Lee Sun Bae Kang Donggyu Kim 《Metals and Materials International》2006,12(3):273-277
In a continuous casting steelmaking operation, the surface of a slab is under a condition that can be characterized as high-temperature,
low-cycle fatigue in which the tensile and compressive stress is repeatedly developed. For this reason, for the evaluation
of the hot ductility of a slab, considering the fatigue deformation is more feasible before a tensile or compressive test.
In this study, the effects of low-cycle fatigue on the hot ductility of steels with a carbon content of 0.06–0.8 wt.% are
investigated at various temperatures. For a carbon content of 0.06%, there were no significant differences between the RA
values from a simple tensile test and those from a tensile test after fatigue deformation. The tendency of ductility deterioration
with fatigue deformation is evident in 0.1 %C steel, and is due to the deformation-induced ferrite film that forms around
the prior austenite grain. Conversely, high carbon steel containing 0.8 %C did not show a recovery of hot ductility in a low
temperature region, and the specimen on which the tensile was measured after fatigue showed a higher hot ductility in the
low temperature region, which is thought to result from the pearlite refinement effects. As the results obtained in this work
showed noticeable differences in the hot ductility of carbon steel through the test conditions, it is suggested that for more
accurate data, fatigue deformation be adopted in which the temperature range in an unbending operation is determined in the
steelmaking factory. 相似文献
136.
Jae?H.?KimEmail author Jung?M.?Lee Ho?C.?Shin Young?H.?Paik 《Metals and Materials International》2003,9(6):593-597
It is known that oxide inclusions in liquid metal carry mostly positive charges on their surfaces. In an electrostatic field,
therefore, such charged particles suspended in a liquid metal experience forces and accumulate in the region of the negatively
charged surface, resulting in the separation of oxide inclusions from the liquid metal. In this study, this principle was
experimentally demonstrated for the case of a capacitor cell by the imposition of a d.c. potential on electrodes. The capacitor
cell consisted of a dielectric container of Pyrex tube, a high voltage d.c. source, and two electrodes, which were symmetrically
attached onto the outer surface of the Pyrex. tube. Experiments were carried out for suspensions of liquid tin/metal oxides,
such as SnO2, WO3, and PbO under an applied potential of up to 12 kV. All experimental results were in good agreement with the theoretical
prediction and showed that the degree of separation was significantly increased with the applied potential. 相似文献
137.
The Cd−Zn system has been thermodynamically reassessed with the CALPHAD method by combining more recent experimental data,
in particular the activities of zinc in the liquid phase. A good agreement is obtained between the calculated and experimental
thermodynamic parameters as well asphase boundaries. 相似文献
138.
Jung Lee 《Behaviour & Information Technology》2015,34(1):57-68
This study challenges the conventional assumption that online customers with high purchase intention routinely move to the purchase stage. To this end, the process of how online customers form purchase intention and behaviour is examined. On the basis of product value distribution (PVD), we propose that the hypothetically expected product value (i.e. PVD average) determines purchase intention, whereas the actual probability of attaining the expected product value (i.e. PVD variance) moderates purchase behaviour. This proposal indicates that the expected product value has significance only when repeated purchase is assumed given that most consumers do not repeatedly purchase the same product in reality. Thus, the actual probability of attaining the expected product value more critically affects customer behaviour than does its expected value. The effectiveness of the research model is verified by conducting a survey on 300 online mall shoppers in Korea. The results confirm model effectiveness. 相似文献
139.
A disturbance observer based practical coordinated tracking controller for uncertain heterogeneous multi‐agent systems
下载免费PDF全文
![点击此处可从《国际强度与非线性控制杂志<br>》网站下载免费的PDF全文](/ch/ext_images/free.gif)
This paper presents a coordinated tracking controller for multi‐agent systems. We assume that agents are uncertain, nonidentical, and affected by external disturbances. The information available to the tracking controller is a weighted sum of relative measurements. A coordinated tracking controller based on the disturbance observer, which is known as a robust output feedback controller, is designed so that the disturbances acting on agents are attenuated and at the same time the weighted sum of relative measurements approximately satisfies a differential equation defined by the leader's dynamics, which results in practical coordinated tracking. Systematic design procedures of the controller as well as numerical simulations are provided. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
140.
This study examines the reasons underlying gender swapping and its impacts on online gaming behavior. While previous studies considered gender swapping to be an abnormal or rare exception in one's self‐presentation, this study hypothesized that people swap genders as a rational choice based on practical benefits. An online survey was conducted with 318 male players of MMORPGs in Korea. Players swapped gender in games to gain benefits from other players under the condition of anonymity rather than to represent their own gender identity. Men playing female avatars displayed more socially amiable behaviors conventionally characterized as more feminine. Moreover, players were more willing to purchase virtual goods to decorate their gender swapped avatars, mediated by their emotional attachment to their avatar. 相似文献