全文获取类型
收费全文 | 4974篇 |
免费 | 282篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 51篇 |
综合类 | 4篇 |
化学工业 | 1153篇 |
金属工艺 | 93篇 |
机械仪表 | 191篇 |
建筑科学 | 192篇 |
矿业工程 | 15篇 |
能源动力 | 133篇 |
轻工业 | 855篇 |
水利工程 | 34篇 |
石油天然气 | 31篇 |
无线电 | 313篇 |
一般工业技术 | 832篇 |
冶金工业 | 689篇 |
原子能技术 | 31篇 |
自动化技术 | 642篇 |
出版年
2024年 | 10篇 |
2023年 | 44篇 |
2022年 | 114篇 |
2021年 | 186篇 |
2020年 | 122篇 |
2019年 | 160篇 |
2018年 | 154篇 |
2017年 | 167篇 |
2016年 | 221篇 |
2015年 | 126篇 |
2014年 | 192篇 |
2013年 | 320篇 |
2012年 | 262篇 |
2011年 | 329篇 |
2010年 | 222篇 |
2009年 | 272篇 |
2008年 | 234篇 |
2007年 | 184篇 |
2006年 | 157篇 |
2005年 | 250篇 |
2004年 | 228篇 |
2003年 | 174篇 |
2002年 | 103篇 |
2001年 | 75篇 |
2000年 | 63篇 |
1999年 | 50篇 |
1998年 | 155篇 |
1997年 | 132篇 |
1996年 | 88篇 |
1995年 | 56篇 |
1994年 | 40篇 |
1993年 | 62篇 |
1992年 | 37篇 |
1991年 | 12篇 |
1990年 | 16篇 |
1989年 | 20篇 |
1988年 | 21篇 |
1987年 | 17篇 |
1986年 | 13篇 |
1985年 | 18篇 |
1984年 | 11篇 |
1983年 | 13篇 |
1982年 | 14篇 |
1981年 | 13篇 |
1980年 | 11篇 |
1979年 | 11篇 |
1978年 | 11篇 |
1977年 | 9篇 |
1976年 | 22篇 |
1975年 | 8篇 |
排序方式: 共有5259条查询结果,搜索用时 15 毫秒
1.
Shin Hansub Sim Sungyong Kwon Hyukyoon Hwang Sangheum Lee Younho 《International Journal of Information Security》2022,21(1):25-36
International Journal of Information Security - This paper deals with a well-known problem in the area of the smudge attacks: when a user draws a pattern to unlock the pattern lock on a smartphone... 相似文献
2.
Vanessa Modelski Schatkoski Thaís Larissa do Amaral Montanheiro Beatriz Rossi Canuto de Menezes Raissa Monteiro Pereira Karla Faquine Rodrigues Renata Guimarães Ribas Diego Morais da Silva Gilmar Patrocínio Thim 《Ceramics International》2021,47(3):2999-3012
Studies related to biomaterials that stimulate the repair of living tissue have increased considerably, improving the quality of many people's lives that require surgery due to traumatic accidents, bone diseases, bone defects, and reconstructions. Among these biomaterials, bioceramics and bioactive glasses (BGs) have proved to be suitable for coating materials, cement, scaffolds, and nanoparticles, once they present good biocompatibility and degradability, able to generate osteoconduction on the surrounding tissue. However, the role of biomaterials in hard tissue engineering is not restricted to a structural replacement or for guiding tissue regeneration. Nowadays, it is expected that biomaterials develop a multifunctional role when implanted, orchestrating the process of tissue regeneration and providing to the body the capacity to heal itself. In this way, the incorporation of specific metal ions in bioceramics and BGs structure, including magnesium, silver, strontium, lithium, copper, iron, zinc, cobalt, and manganese are currently receiving enhanced interest as biomaterials for biomedical applications. When an ion is incorporated into the bioceramic structure, a new category of material is created, which has several unique properties that overcome the disadvantages of primitive material and favors its use in different biomedical applications. The doping can enhance handling properties, angiogenic and osteogenic performance, and antimicrobial activity. Therefore, this review aims to summarize the effect of selected metal ion dopants into bioceramics and silicate-based BGs in bone tissue engineering. Furthermore, new applications for doped bioceramics and BGs are highlighted, including cancer treatment and drug delivery. 相似文献
3.
The design of a microstrip‐fed annular‐ring slot antenna (ARSA) with circular polarization (CP) radiation is initially studied. To obtain CP radiation with broad 3‐dB axial ratio (AR) bandwidth that can cover the WiMAX 2.3 GHz (2305–2320 MHz, 2345–2360 MHz) and WLAN 2.4 GHz (2400–2480 MHz) bands, a novel technique of extending an inverted L‐shaped slot from the bottom section of the annular‐ring is proposed. To suppress the harmonic modes induced by the CP ARSA, the technique of integrating a defected ground structure into the annular‐ring slot is further introduced. From the measured results, 10‐dB impedance bandwidth and 3‐dB AR bandwidth of 44.86 and 9.68% were achieved by the proposed harmonic suppressed CP ARSA. Furthermore, average gain and radiation efficiency of ~4.7 dBic and 71%, respectively, were also exhibited across the bands of interest. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:337–345, 2015. 相似文献
4.
Ricardo Cambraia Parreira Diana Paola Gmez‐Mendoza Itamar Couto Guedes de Jesus Rafael Pereira Lemos Anderson Kennedy Santos Cristiana Perdigo Rezende Henrique Csar Pereira Figueiredo Mauro Cunha Xavier Pinto Frank Kjeldsen Silvia Guatimosim Rodrigo Ribeiro Resende Thiago Verano‐Braga 《Proteomics. Clinical applications》2020,14(4)
5.
6.
7.
The present study focuses on the sintering of silicon carbide-based ceramics (SiC) by liquid phase sintering (LPS) followed by characterization of the produced ceramics. AlN/Re2O3 mixtures were used as additives in the LPS process. In the first step, the LPS-SiC materials were produced in a graphite resistance furnace in the form of discs at different temperatures. The conditions with the best results regarding real density and relative density were taken as reference for sintering in the form of prismatic bars. In the second step, these samples were evaluated regarding fracture toughness (KIC), by the Single Edge V Notch Beam – SEVNB – method, and flexural strength. KIC behavior was evaluated according to the depth and curvature radius of the notches. Reliable KIC values were presented when the ceramic displayed a small curvature radius at the notch tip. When the radius was large, it did not maintain the square root singularity of the notch tip. Tests were carried out to determine KIC values in atmospheric air and water. KIC results were lower in water than air, with a decrease ranging between 2.56% and 11.26%. The observations indicated a direct grain size correlation between KIC values and fracture strength of the SiC ceramics. 相似文献
8.
DeLongis Anita; Capreol Martha; Holtzman Susan; O'Brien Tess; Campbell Jennifer 《Canadian Metallurgical Quarterly》2004,18(3):470
In response to recent calls in the literature for within-person examinations of social support processes over time, this study explores the relationships of spousal support, spousal strain, and well-being among husbands and wives, both within the same day and across days. Eighty-three couples were interviewed and completed a structured diary twice daily for 1 week. The results of multilevel hierarchical modeling suggest that both spousal support and spousal strain made significant, independent contributions to concurrent negative affect, although only spousal support was a significant predictor of next-day negative affect. Spousal strain interacted with spousal support to predict next-day negative affect. Direct and moderating effects of perceived marital adjustment on negative affect were discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
Surveyed 70 practicing attorneys and 150 law students to determine the extent to which they felt it was their responsibility to inform clients they referred for psychological testing about the testing process and about the validity scales on tests. Results showed that almost 50% of the attorneys and over 33% of the students believe that clients referred for testing always or usually should be informed of validity scales on tests. These results suggest that many test takers, particularly in forensic settings, may have information about validity scales that facilitates their giving biased responses without detection. Psychologists doing forensic evaluations should be alert to this possibility and should consider using more than one approach to detect response distortions. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
10.
The wetting of Ti–Cu alloys on Si3N4 was analyzed by the sessile drop method, using an imaging system with a CCD camera during the heating under argon flow. The contact angle was measured as a function of temperature and time. The samples were cut transversally and characterized by scanning electron microscopy and energy dispersive spectrometry (SEM/EDS). Wettability of the Ti–Cu alloy on Si3N4 is influenced by the reaction between the Ti and the ceramic. The TC1 and TC2 alloys presented low final contact angle values around 2° and 26°, respectively, indicating good wetting on Si3N4. 相似文献