全文获取类型
收费全文 | 21343篇 |
免费 | 1322篇 |
国内免费 | 55篇 |
专业分类
电工技术 | 309篇 |
综合类 | 25篇 |
化学工业 | 4533篇 |
金属工艺 | 878篇 |
机械仪表 | 1300篇 |
建筑科学 | 426篇 |
矿业工程 | 6篇 |
能源动力 | 856篇 |
轻工业 | 1840篇 |
水利工程 | 90篇 |
石油天然气 | 15篇 |
无线电 | 3648篇 |
一般工业技术 | 4612篇 |
冶金工业 | 1539篇 |
原子能技术 | 291篇 |
自动化技术 | 2352篇 |
出版年
2023年 | 264篇 |
2022年 | 132篇 |
2021年 | 654篇 |
2020年 | 470篇 |
2019年 | 496篇 |
2018年 | 699篇 |
2017年 | 661篇 |
2016年 | 769篇 |
2015年 | 602篇 |
2014年 | 938篇 |
2013年 | 1389篇 |
2012年 | 1456篇 |
2011年 | 1790篇 |
2010年 | 1298篇 |
2009年 | 1333篇 |
2008年 | 1213篇 |
2007年 | 938篇 |
2006年 | 815篇 |
2005年 | 711篇 |
2004年 | 638篇 |
2003年 | 590篇 |
2002年 | 593篇 |
2001年 | 518篇 |
2000年 | 437篇 |
1999年 | 410篇 |
1998年 | 677篇 |
1997年 | 399篇 |
1996年 | 371篇 |
1995年 | 255篇 |
1994年 | 167篇 |
1993年 | 152篇 |
1992年 | 109篇 |
1991年 | 99篇 |
1990年 | 75篇 |
1989年 | 86篇 |
1988年 | 74篇 |
1987年 | 63篇 |
1986年 | 51篇 |
1985年 | 43篇 |
1984年 | 36篇 |
1983年 | 28篇 |
1982年 | 31篇 |
1981年 | 26篇 |
1980年 | 27篇 |
1979年 | 13篇 |
1977年 | 21篇 |
1976年 | 33篇 |
1975年 | 16篇 |
1974年 | 13篇 |
1973年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Transient Electronics: Thermally Triggered Degradation of Transient Electronic Devices (Adv. Mater. 25/2015) 下载免费PDF全文
992.
DNA/Tannic Acid Hybrid Gel Exhibiting Biodegradability,Extensibility, Tissue Adhesiveness,and Hemostatic Ability 下载免费PDF全文
Mikyung Shin Ji Hyun Ryu Joseph P. Park Keumyeon Kim Jae Wook Yang Haeshin Lee 《Advanced functional materials》2015,25(8):1270-1278
DNA has emerged as a novel material in many areas of materials science due to its programmability. Especially, DNA hydrogels have been studied to incorporate new functions into gels. To date, only a few methods have been developed for fabricating DNA hydrogels, such as the use of complementary sequences or covalent bond. Herein, it is demonstrated that one of the most well‐known plant‐derived polyphenols, tannic acid (TA), can form a DNA hydrogel which is named TNA hydrogel ( T A + D NA ). TA plays a role as a “molecular glue” by a new mode of action reversibly connecting between phosphodiester bonds, which is different from the crosslinking utilizing complementary sequences. TA intrinsically degrades due to ester bonds connecting between pyrogallol groups, causing a degradable DNA hydrogel. Furthermore, TNA gel is multifunctional in that the gel is extensible upon pulling and adhesive to tissues because of the rich polyphenol groups in TA (ten phenols per TA). Unexpectedly, TNA gel exhibits superior in vivo hemostatic ability that can be useful for biomedical applications. This new DNA hydrogel preparation method represents a new technique for fabricating a large amount of DNA‐based hemostatic hydrogel without chemically modifying DNA or requiring the crosslinking by complementary sequences. 相似文献
993.
Yu Ra Jeong Heun Park Sang Woo Jin Soo Yeong Hong Sang‐Soo Lee Jeong Sook Ha 《Advanced functional materials》2015,25(27):4228-4236
Stretchable electronics have recently been extensively investigated for the development of highly advanced human‐interactive devices. Here, a highly stretchable and sensitive strain sensor is fabricated based on the composite of fragmentized graphene foam (FGF) and polydimethylsiloxane (PDMS). A graphene foam (GF) is disintegrated into 200–300 μm sized fragments while maintaining its 3D structure by using a vortex mixer, forming a percolation network of the FGFs. The strain sensor shows high sensitivity with a gauge factor of 15 to 29, which is much higher compared to the GF/PDMS strain sensor with a gauge factor of 2.2. It is attributed to the great change in the contact resistance between FGFs over the large contact area, when stretched. In addition to the high sensitivity, the FGF/PDMS strain sensor exhibits high stretchability over 70% and high durability over 10 000 stretching‐releasing cycles. When the sensor is attached to the human body, it functions as a health‐monitoring device by detecting various human motions such as the bending of elbows and fingers in addition to the pulse of radial artery. Finally, by using the FGF, PDMS, and μ‐LEDs, a stretchable touch sensor array is fabricated, thus demonstrating its potential application as an artificial skin. 相似文献
994.
High‐Performance Transition Metal Dichalcogenide Photodetectors Enhanced by Self‐Assembled Monolayer Doping 下载免费PDF全文
Dong‐Ho Kang Myung‐Soo Kim Jaewoo Shim Jeaho Jeon Hyung‐Youl Park Woo‐Shik Jung Hyun‐Yong Yu Chang‐Hyun Pang Sungjoo Lee Jin‐Hong Park 《Advanced functional materials》2015,25(27):4219-4227
Most doping research into transition metal dichalcogenides (TMDs) has been mainly focused on the improvement of electronic device performance. Here, the effect of self‐assembled monolayer (SAM)‐based doping on the performance of WSe2‐ and MoS2‐based transistors and photodetectors is investigated. The achieved doping concentrations are ≈1.4 × 1011 for octadecyltrichlorosilane (OTS) p‐doping and ≈1011 for aminopropyltriethoxysilane (APTES) n‐doping (nondegenerate). Using this SAM doping technique, the field‐effect mobility is increased from 32.58 to 168.9 cm2 V?1 s in OTS/WSe2 transistors and from 28.75 to 142.2 cm2 V?1 s in APTES/MoS2 transistors. For the photodetectors, the responsivity is improved by a factor of ≈28.2 (from 517.2 to 1.45 × 104 A W?1) in the OTS/WSe2 devices and by a factor of ≈26.4 (from 219 to 5.75 × 103 A W?1) in the APTES/MoS2 devices. The enhanced photoresponsivity values are much higher than that of the previously reported TMD photodetectors. The detectivity enhancement is ≈26.6‐fold in the OTS/WSe2 devices and ≈24.5‐fold in the APTES/MoS2 devices and is caused by the increased photocurrent and maintained dark current after doping. The optoelectronic performance is also investigated with different optical powers and the air‐exposure times. This doping study performed on TMD devices will play a significant role for optimizing the performance of future TMD‐based electronic/optoelectronic applications. 相似文献
995.
Kim JeongJu Sohn Ho-Seong Park Hee Seung Hsu Wei-Ting Ueda Osamnu Cho Hyung Hee 《Journal of Mechanical Science and Technology》2021,35(10):4575-4583
Journal of Mechanical Science and Technology - Recently, domestic gas turbines are primarily operated under partial loads. Hence, thermal expansion of components decreases, leading to a... 相似文献
996.
Delay‐ or Disruption‐Tolerant Networking (DTN) is a communications approach that is utilized in easily disrupted or delayed networks. Examples of such networks are often found in heterogeneous networks, mobile or extreme terrestrial networks, and planned networks in space. In this paper, we examine the metropolitan bus network as a research target of DTN for a public transport network. We analyze the metropolitan bus network through spatial and temporal modeling using an existing Bus Information System (BIS) database. On the basis of the results of our analysis, we propose and design an appropriate DTN routing scheme called Hybrid Position‐based DTN Routing. This scheme uses position‐based routing instead of address‐based routing by soliciting infrastructural help from nearby Access Points for the real‐time BIS location service. We simulated our scheme using a WLAN for the wideband DTN communication and evaluated it by comparing it with traditional Ad hoc flooding, Epidemic routing, and strategic protocol steps in our own algorithm. The results indicate that our scheme achieves reasonably high performance in terms of packet delivery ratio, latency, and resource usage. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
997.
Soohyun Kim Kashif Ghafoor Jooyoung Lee Mei Feng Jungyeon Hong Dong-Un Lee Jiyong Park 《Water research》2013,47(13):4403-4411
The effects of UV-assisted TiO2-photocatalytic oxidation (PCO) inactivation of pathogenic bacteria (Escherichia coli O157:H7, Listeria monocytogenes, Salmonella typhimurium) in a liquid culture using different domains of UV irradiation (A, B and C) were evaluated. Structural changes in super-coiled plasmid DNA (pUC19) and genomic DNA of E. coli were observed using gel electrophoresis to demonstrate the photodynamic DNA strand breaking activity of UV-assisted TiO2-PCO. Membrane damage in bacterial cells was observed using both a scanning electron microscope (SEM) and a confocal laser scanning microscope (CLSM). Both UVC-TiO2-PCO and UVC alone resulted in an earlier bactericidal phase (initial counts of approximately 6 log CFU/mL) in 60 s and 90 s, respectively, in liquid culture. UVC-TiO2-PCO treatment for 6 min converted all plasmid DNA to the linear form; however, under UVC irradiation alone, super-coiled DNA remained. Prolonged UVC-TiO2-PCO treatment resulted in structural changes in genomic DNA from E. coli. SEM observations revealed that bacteria suffered severe visible cell damage after UVC-TiO2-PCO treatment for 30–60 min. S. typhimurium cells showed visible damage after 30 min, which was confirmed using CLSM. All treated cells were stained red using propidium iodide under a fluorescent light. 相似文献
998.
One particular aspect of a wide range of HVAC research at the US Center for Building Technology concerned interfacing DDC with the pneumatic system for one of the existing air handling units at the CBT building itself. Using solenoid air valves induced both positive and negative air leaks in the pneumatic system; this did not occur with motorised pressure regulators, though these produced a time delay whenever the regulator's direction of rotation was reversed. Details are given of an adaptive PI algorithm with a self‐tuning regulator approach, developed at CBT and implemented on the air handler in question. From the experience, it is strongly recommended that such an algorithm should be implemented on a positional basis. 相似文献
999.
Jin-Ho Park 《The Journal of Architecture》2013,18(1):37-54
Rudolph Michael Schindler has been known as the first and foremost space architect, in his own words, whose devotion to space as defining architecture remained vital and remarkably consistent throughout his professional career. The purpose of this article is systematically to interpret Schindler's theory of space architecture, and then to discuss his theoretical project: Space Development. The first part investigates Schindler's underlying forms of conception. For Schindler, forms of architecture begin with the space architect's process of thinking, shaping, and feeling the building in the mind. Using a recently uncovered series of Schindler's 1916 lecture notes, from the Schindler archive at the University of California, Santa Barbara (UCSB), the investigation presents a new and critical examination of his theory. The second part interprets his theoretical project, Space Development, to strengthen the understanding of Schindler's notion of space architecture. Along with Space Development, Schindler also evolved two related projects in the same year, sharing the same compositional logic. This article further examines the spatial paradigm pertinent to his Space Development, investigates its relationship to two other designs, and demonstrates how his design theory became further clarified and strengthened through it in the final phase of his career. 相似文献
1000.
Sung Woo Park Se Woon Choi Hyo Seon Park 《The Structural Design of Tall and Special Buildings》2013,22(9):718-728
The differential length changes of vertical members in a high‐rise building due to elastic, creep and shrinkage shortenings are of primary concern since the differential shortening of the vertical members causes unexpected damages on structural and nonstructural members. In contrast to researches on prediction methods for calculation of the amount of the shortenings, only few methods or algorithms of compensation of the differential column shortenings have been reported. In this paper, a practical compensation method using moving average correction is presented. The proposed method is applied to the compensation of the differential shortenings of the vertical members in a 70‐story high‐rise building. The performance of the moving average correction method is compared with the optimal compensation method based on simulated annealing algorithm. It is demonstrated that the magnitude of the differential shortening or the degree of the slab tilt due to the length changes in the vertical members can be controlled without using structural optimization techniques. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献