全文获取类型
收费全文 | 15348篇 |
免费 | 1073篇 |
国内免费 | 31篇 |
专业分类
电工技术 | 179篇 |
综合类 | 13篇 |
化学工业 | 3422篇 |
金属工艺 | 630篇 |
机械仪表 | 849篇 |
建筑科学 | 322篇 |
矿业工程 | 10篇 |
能源动力 | 532篇 |
轻工业 | 1458篇 |
水利工程 | 54篇 |
石油天然气 | 22篇 |
无线电 | 2349篇 |
一般工业技术 | 3161篇 |
冶金工业 | 1705篇 |
原子能技术 | 184篇 |
自动化技术 | 1562篇 |
出版年
2023年 | 156篇 |
2022年 | 242篇 |
2021年 | 396篇 |
2020年 | 297篇 |
2019年 | 359篇 |
2018年 | 435篇 |
2017年 | 460篇 |
2016年 | 541篇 |
2015年 | 455篇 |
2014年 | 699篇 |
2013年 | 1033篇 |
2012年 | 919篇 |
2011年 | 1125篇 |
2010年 | 788篇 |
2009年 | 802篇 |
2008年 | 761篇 |
2007年 | 621篇 |
2006年 | 530篇 |
2005年 | 474篇 |
2004年 | 451篇 |
2003年 | 419篇 |
2002年 | 368篇 |
2001年 | 310篇 |
2000年 | 257篇 |
1999年 | 277篇 |
1998年 | 599篇 |
1997年 | 412篇 |
1996年 | 271篇 |
1995年 | 203篇 |
1994年 | 202篇 |
1993年 | 200篇 |
1992年 | 134篇 |
1991年 | 102篇 |
1990年 | 105篇 |
1989年 | 103篇 |
1988年 | 70篇 |
1987年 | 65篇 |
1986年 | 66篇 |
1985年 | 79篇 |
1984年 | 79篇 |
1983年 | 49篇 |
1982年 | 43篇 |
1981年 | 44篇 |
1980年 | 43篇 |
1979年 | 40篇 |
1978年 | 34篇 |
1977年 | 52篇 |
1976年 | 81篇 |
1975年 | 41篇 |
1973年 | 33篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
Chun Woo Young; Kruglanski Arie W.; Sleeth-Keppler David; Friedman Ronald S. 《Canadian Metallurgical Quarterly》2011,101(5):1124
This research examines the possibility that people's choices in the service of an explicit focal goal may also reflect their tendency to fulfill implicit background goals and in that sense are multifinal. We carried out 5 experimental studies to investigate this notion. In Experiment 1, a primed implicit goal affected individuals' choices even when those avowedly served an explicit “focal” goal. Experiment 2 replicated this finding with a different type of implicit goals. Experiment 3 found that primed implicit goals had no effect on choices where the options that served them undermined the explicit goal. Experiment 4 found that a primed implicit goal served by a multifinal option does not privilege it over a unifinal option if that goal had been already attained by a different means. Finally, Experiment 5, via 3 types of control groups, showed that choices were affected by both the explicit and implicit goals in isolation, and they shifted toward multifinality when these goals were conjointly present. The discussion considers the integrative potential of the multifinality framework and its implications for a variety of phenomena in the domain of motivated cognition. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
82.
Tae Woo Kim Hana Yoo In Young Kim Hyung‐Wook Ha Ah Reum Han Jong‐San Chang Ji Sun Lee Seong‐Ju Hwang 《Advanced functional materials》2011,21(12):2301-2310
Manganese oxide nanocrystals are combined with aluminum oxide nanocrystals to improve their crystallinity via calcination without a significant increase of crystal size. A nanocomposite, consisting of two metal oxides, can be synthesized by the reaction between permanganate anions and aluminum oxyhydroxide keggin cations. The as‐prepared manganese oxide–aluminum oxide nanocomposite is X‐ray amorphous whereas heat‐treatment gives rise to the crystallization of an α‐MnO2 phase at 600 °C and Mn3O4/Mn2O3 and γ‐Al2O3 phases at 800 °C. Electron microscopy and N2 adsorption‐desorption‐isotherm analysis clearly demonstrate that the as‐prepared nanocomposite is composed of a porous assembly of monodisperse primary particles with a size of ~20 nm and a surface area of >410 m2 g?1. Of particular interest is that the small particle size of the as‐prepared nanocomposite is well‐maintained up to 600 °C, a result of the prevention of the growth of manganate grains through nanoscale mixing with alumina grains. The calcined nanocomposite shows very‐high catalytic activity for the oxidation of cyclohexene with an extremely high conversion efficiency of >95% within 15 min. The present results show that the improvement of the crystallinity without significant crystal growth is very crucial for optimizing the catalytic activity of manganese oxide nanocrystals. 相似文献
83.
Vivanti Giacomo; McCormick Carolyn; Young Gregory S.; Abucayan Floridette; Hatt Naomi; Nadig Aparna; Ozonoff Sally; Rogers Sally J. 《Canadian Metallurgical Quarterly》2011,47(3):841
Typically developing children understand and predict others' behavior by extracting and processing relevant information such as the logic of their actions within the situational constraints and the intentions conveyed by their gaze direction and emotional expressions. Children with autism have difficulties understanding and predicting others' actions. With the use of eye tracking and behavioral measures, we investigated action understanding mechanisms used by 18 children with autism and a well-matched group of 18 typically developing children. Results showed that children with autism (a) consider situational constraints in order to understand the logic of an agent's action and (b) show typical usage of the agent's emotional expressions to infer his or her intentions. We found (c) subtle atypicalities in the way children with autism respond to an agent's direct gaze and (d) marked impairments in their ability to attend to and interpret referential cues such as a head turn for understanding an agent's intentions. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
84.
This study describes the development process of Kor-Factor, which is a novel composite evaluation index that was developed to promote Korean domestic academic journals. As more data accumulate, the Kor-Factor’s optimization process was modified in an attempt to address possible drawbacks of the original form; the result is presented in this study. This study compares Kor-Factor with the Impact Factor, which is the most well-known single element evaluation index. We found that Kor-Factor demonstrates a better power of differentiation and a greater capacity to reflect the reputability of key journals. The modified Kor-Factor, which has been developed through an optimization process, reveals a greater power of differentiation than the original Kor-Factor; however, the modified version has less capacity to reflect reputability. The evaluation elements of the modified Kor-Factor are better and are more evenly reflected on the index value than those of the original version. Finally, we propose the establishment of an appropriate data measurement period for the actual application of the index. 相似文献
85.
The notion of a BCK-valued function on a set is introduced, and related properties are investigated. Codes generated by BCK-valued functions are established. 相似文献
86.
K. Young T. Ouchi B. Reichman W. Mays R. Regmi G. Lawes M.A. Fetcenko A. Wu 《Journal of Alloys and Compounds》2010,489(1):202-210
The structural, electrochemical, and gas phase hydrogen storage properties of predominantly C14 crystalline phase alloys with partial replacement by Co (up to 2.5 at%) are reported. Minor phases, including C15 and cubic TiNi, were found by X-ray diffraction and contributed to the improved hydrogen diffusion through the alloy. The optimal Co-content of between 1.0 and 1.5 at% provides easy activation, high gas phase capacity, and a high discharge capacity. An optimized alloy formula also provided the smallest metallic nickel cluster size embedded in the surface oxide and the largest number of nickel clusters. In sealed cell studies, a Co-content of 1.5% gives the best performance in formation, cycle life, and charge retention, but has worse specific power and low temperature performance than some other compositions. The high-rate dischargeabilities at lower rates were found to be limited by surface reactions, not bulk diffusion. 相似文献
87.
Kee Do Woo Jae Hwang Kim Eui Pyo Kwon Min Seok Moon Hyun Bom Lee Tatsuo Sato Zhiguang Liu 《Metals and Materials International》2010,16(2):213-218
To fabricate an Al-V matrix composite reinforced with submicron-sized Al2O3 and AlxVy (Al3V, Al10V) phases, high energy mechanical milling (HEMM) and sintering were employed. By increasing the milling time, the size of mechanically milled powder was significantly reduced. In this study, the average powder size of 59 μm for Al, and 178 μm for V2O5 decreased with the formation of a new product, Al-Al2O3-AlxVy, with a size range from 1.3 μm to 2.6 μm formed by the in-situ combustion reaction during sintering of HEM milled Al and V2O5 composite powders. The in-situ reaction between Al and V2O5 during the HEMM and sintering transformed the Al2O3 and AlxVy (Al3V, Al10V) phases. Most of the reduced V reacted with excess the Al to form AlxVy (Al3V, Al10V) with very little V dissolved into Al matrix. By increasing the milling time and weight percentage of V2O5, the hardness of the Al-Al2O3-AlxVy composite sintered at 1173 K increased. The composite fabricated with the HEMM Al-20wt.%V2O5 composite powder and sintering at 1173 K for 2 h had the highest hardness. 相似文献
88.
Nac‐Woo Kim Byung‐Tak Lee Young‐Sun Kim 《International Journal of Communication Systems》2013,26(11):1382-1394
In this paper, we propose a personally customizable content authoring service (C2Channel) using an Internet Protocol television (IPTV) platform, in which a user terminal such as a PC or set‐top box sends various kinds of multimedia files from a camera or camcorder to a remotely located authoring server (C2Channel server). The C2Channel server creates personalized content in real time by combining special effects with the multimedia files transmitted from the user terminal and then retransmits them to a predefined relevant service group as a personal IPTV channel through an IPTV network provider. This content authoring service supplies an automatic multimedia editing/composition service and offers unicast, multicast, and groupcast services for a large number of interested groups via an IPTV‐based real‐time media delivery platform (Open Live IPTV Engine [OLIVE]), in which a service management server is used for user identification through the IPTV personal channel. Because this platform uses a remote server resource when authoring personally customizable content, resources remaining at the user's terminal can be variously utilized. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
89.
Gyeonghye Yim Seounghun Kang Hyungjun Kim Young‐Jin Kim Yeong‐Gyu Gil Young‐Kwan Kim Dal‐Hee Min Hongje Jang 《Advanced functional materials》2020,30(9)
The synthesis of nanostructures using homogeneous precursors in the solution phase is widely used to achieve uniformity and well‐defined morphological control. However, drawbacks such as the lack of diversity due to the limited reaction rate modulation exist. One‐step, core–shell nanorod formation using simultaneous covering synthesis using solid and ionic heterogeneous precursors is proposed in this study. A Te‐Bi2Te3/TeO2 core–shell structure is successfully synthesized by precisely controlling various influencing factors, including concentration, temperature, and pH, and its physicochemical and photochemical properties are thoroughly investigated. The proposed nanostructure overcomes the oxidation susceptibility of Te and can be applied to multipotent cancer theranostics in vitro and in vivo in combination with computed tomography imaging. 相似文献
90.
Seung-Chul Lee Young-Deuk Jeon Jong-Kee Kwon Jongdae Kim 《Solid-State Circuits, IEEE Journal of》2007,42(12):2688-2695
This paper describes a 10-bit 205-MS/s pipeline analog-to-digital converter (ADC) for flat panel display applications with the techniques to alleviate the design limitations in the deep-submicron CMOS process. The switched source follower combined with a resistor-switch ladder eliminates the sampling switches and achieves high linearity for a large single-ended input signal. Multistage amplifiers adopting the complementary common-source topology increase the output swing range with lower transconductance variation and reduce the power consumption. The supply voltage for the analog blocks is provided by the low drop-out regulator for a high power-supply rejection ratio (PSRR) under the noisy operation environment. The pipeline stages of the ADC are optimized in the aspect of power consumption through the iterated calculation of the sampling capacitance and transconductance. The ADC occupies an active area of 1.0 mm2 in a 90-nm CMOS process and achieves a 53-dB PSRR for a 100-MHz noise tone with the regulator and a 55.2-dB signal-to-noise-and-distortion ratio for a 30-MHz 1.0-VPP single-ended input at 205 MS/s. The ADC core dissipates 40 mW from a 1.0-V nonregulated supply voltage. 相似文献