全文获取类型
收费全文 | 1617篇 |
免费 | 38篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 70篇 |
综合类 | 1篇 |
化学工业 | 281篇 |
金属工艺 | 44篇 |
机械仪表 | 38篇 |
建筑科学 | 33篇 |
能源动力 | 59篇 |
轻工业 | 123篇 |
水利工程 | 5篇 |
石油天然气 | 8篇 |
无线电 | 232篇 |
一般工业技术 | 201篇 |
冶金工业 | 411篇 |
原子能技术 | 28篇 |
自动化技术 | 124篇 |
出版年
2023年 | 6篇 |
2022年 | 14篇 |
2021年 | 25篇 |
2020年 | 8篇 |
2019年 | 6篇 |
2018年 | 21篇 |
2017年 | 20篇 |
2016年 | 21篇 |
2015年 | 17篇 |
2014年 | 29篇 |
2013年 | 63篇 |
2012年 | 43篇 |
2011年 | 66篇 |
2010年 | 55篇 |
2009年 | 62篇 |
2008年 | 52篇 |
2007年 | 56篇 |
2006年 | 59篇 |
2005年 | 45篇 |
2004年 | 41篇 |
2003年 | 45篇 |
2002年 | 51篇 |
2001年 | 40篇 |
2000年 | 45篇 |
1999年 | 41篇 |
1998年 | 151篇 |
1997年 | 98篇 |
1996年 | 84篇 |
1995年 | 49篇 |
1994年 | 42篇 |
1993年 | 44篇 |
1992年 | 19篇 |
1991年 | 28篇 |
1990年 | 10篇 |
1989年 | 16篇 |
1988年 | 17篇 |
1987年 | 20篇 |
1986年 | 16篇 |
1985年 | 27篇 |
1984年 | 16篇 |
1983年 | 12篇 |
1982年 | 11篇 |
1981年 | 12篇 |
1980年 | 7篇 |
1979年 | 10篇 |
1977年 | 7篇 |
1976年 | 13篇 |
1975年 | 5篇 |
1972年 | 5篇 |
1971年 | 2篇 |
排序方式: 共有1658条查询结果,搜索用时 15 毫秒
71.
Makoto Tanaka Mikio Taguchi Tsuysohi Takahama Toru Sawada Shigeru Kuroda Takao Matsuyama Shinya Tsuda Akio Takeoka Shoichi Nakano Hiroshi Hanafusa Yukinori Kuwano 《Progress in Photovoltaics: Research and Applications》1993,1(2):85-92
A new solar cell structure named HIT (Heterojunction with Intrinsic Thin layer) has been developed based on new artificially constructed junction (ACJ) technology. In this structure a non-doped a-Si thin layer was inserted between the p(a-Si)/n(c-Si) heterojunction, improving the output characteristics and achieving a conversion efficiency of 18.1%. This structure was applied to cast polycrystalline silicon solar cells of a practical size. A high conversion efficeincy of 13.6% was obtained with a cell size of 10 cm × 10 cm using various technologies, including hydrogen plasma passivation. 相似文献
72.
A. Takeoka Y. Fukuda M. Suzuki M. Hasunuma E. Sakoguchi H. Tokizaki S. Kouzuma M. Waki M. Ohnishi S. Nakano Y. Kuwano 《Progress in Photovoltaics: Research and Applications》1993,1(1):47-54
We have successfully developed and industrialized a solar-powered air conditioner that operates through a combination of photovoltaic (PV) arrays and commercial power supplies. In order to achieve the most efficient operation possible from a one-horsepower inverter-type household air conditioner, we selected a PV array output of 540 W under standard test conditions, based on single-day power use patterns for air conditioners as well as on solar cell output patterns. When using a 540-W PV array, we have shown that the system can supply at least 90% of the power consumed by an air conditioner during peak power periods in summer. We have confirmed that on average the power generated by the PV array can satisfy at least 50% of the power consumed by an air conditioner in summer. We also confirmed that the system functions according to system design specifications. There is little doubt that the introduction and widespread use of this system will play an important role in reducing peak power energy requirements in summer. 相似文献
73.
Masato Nishikuni Tsuyoshi Takahama Shingo Okamoto Kunimoto Ninomiya Hidenori Nishiwaki Shinya Tsuda Akio Takeoka Michotoshi Ohnishi Shoichi Nakano Yukinori Kuwano 《Progress in Photovoltaics: Research and Applications》1994,2(3):211-219
A new approach to high-performance a-Si solar cells was studied. a-Si films prepared at a high substrate temperature (> 250°C) have a higher absorption coefficient and a low Si H2 bond density. the effect of deposition temperature on the open-circuit voltage (Voc) has been investigated systematically for glass/SnO2 Ipin/metal and glass/metal/nip/indium tin oxide (ITO) structure a-Si solar cells. The Voc is found to depend strongly on the thermal history of the p/i interface. A short-circuit current of 19.5 mA/cm−−2 was achieved for an a-Si solar cell using an a-Si i-layer with a thickness of 4000 Å, which was prepared at a substrate temperature of 270°C. 相似文献
74.
Mutational analysis of structure--activity relationships in human tumor necrosis factor-alpha 总被引:1,自引:0,他引:1
Yamagishi Jun-ichi; Kawashima Hitoshi; Matsuo Noriyuki; Ohue Mayumi; Yamayoshi Michiko; Fukui Toshikazu; Kotani Hirotada; Furuta Ryuji; Nakano Katsuji; Yamada Masaaki 《Protein engineering, design & selection : PEDS》1990,3(8):713-719
To determine the region of human tumor necrosis factor-alpha(TNF-), essential for cytotoxic activity against mouse L-M cells,single amino-acid-substituted TNF- mutant proteins (muteins)were produced in Escherichia coli by protein engineering techniques.An expression plasmid for TNF- was mutagenized by passage throughan E.coli mutD5 mutator strain and by oligonucleotide-directedmutagenesis. Approximately 100 single amino-acid-substitutedTNF- muteins were produced and assayed for cytotoxic activity.The cytotoxic activities of purified TNF- muteins, e.g. TNF-31T,-32Y, -82D, -85H, -115L, -141Y, -144K and -146E, were < 1%of that of parent TNF-. These results indicate that the integrityof at least four distinct regions of the TNF- molecule is requiredfor full biological activity. These regions are designated asfollows: region I, from position 30 to 32; region II, from position82 to 89; region III, from position 115 to 117; region FV, fromposition 141 to 146. In addition, TNF-141Y could not completelycompete with parent TNF- for binding to the receptor. This demonstratesthat region IV, and at least aspartk acid at position 141, mustbe involved in the TNF receptor binding site. 相似文献
75.
Noriaki Ikenaga Yoichi Kishi Zenjiro Yajima Noriyuki Sakudo Shizuka Nakano Hisato Ogiso 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2009,267(8-9):1509-1513
TiNi alloy samples implanted with various fluences of 3 MeV Cu2+ ions were characterized by transmission electron microscope (TEM) and X-ray diffractometer. Cross-sectional TEM images of the samples showed that amorphous region was seen at the fluence of 1014 ions cm?2 in case of ion implantation at 300 K of the substrate temperature, but in case of ion implantation at 100 K it did not appear even at 1015 ions cm?2. These results were also confirmed by X-ray diffraction profiles of the same samples. Consequently, the extent of microstructure change of TiNi alloy by ion implantation was different depending on the substrate temperature. 相似文献
76.
77.
J. Yamamatsu N. Kawano T. Arashi A. Sato Y. Nakano T. Nomura 《Journal of power sources》1996,60(2):199-203
The reliability of multilayer ceramic capacitors (MLCCs) with Ni internal electrodes has been studied trom the viewpoint of partial oxygen pressure (PO2) during firing. It is shown that the load-life time of the insulation resistance (1R) was prolonged by firing under low Po2 annealing after firing, and the addition of dopants. It is also shown that the generation of oxygen vacancies led to the degradation of IR. Annealing treatment for the oxidation of the dielectric body accelerates the dielectric aging of MLCCs. It is found that the appropriate control of the PO2 during firing can improve the reliability of MLCCs with Ni electrodes to a level as high as that of MLCCs with precious metal electrodes. Thus, we have developed an MLCC with Ni electrodes that features high reliability and a large capacitance of 10 μF for the Y5V characteristic and 4.7 μF for the X7R characteristic, both in the case of the C3216 (3.2 mm × 1.6 mm × 1.4 mm) form. 相似文献
78.
Carbon Nanotubes: Simple Salt‐Coordinated n‐Type Nanocarbon Materials Stable in Air (Adv. Funct. Mater. 18/2016)
下载免费PDF全文
![点击此处可从《Advanced functional materials》网站下载免费的PDF全文](/ch/ext_images/free.gif)
79.
Effect of Ultrasonication on the Microstructure and Tensile Elongation of Zirconia-Dispersed Alumina Ceramics Prepared by Colloidal Processing 总被引:1,自引:0,他引:1
Tohru S. Suzuki Yoshio Sakka Keishi Nakano Keijiro Hiraga 《Journal of the American Ceramic Society》2001,84(9):2132-2134
To obtain dense, fine-grained ceramics, fine particles and advanced powder processing, such as colloidal processing, are needed. Al2 O3 and ZrO2 particles are dispersed in colloidal suspensions by electrosteric repulsion because of polyelectrolyte absorbed on their surfaces. However, additional redispersion treatment such as ultrasonication is required to obtain dispersed suspensions because fine particles tend to agglomerate. The results demonstrate that ultrasonication is effective in improving particle dispersion in suspensions and producing a homogeneous fine microstructure of sintered materials. Superplastic tensile ductility is improved by ultrasonication in preparing suspensions because of the dense and homogeneous fine microstructure. 相似文献
80.
Keiichiro Sugimoto Sayaka Sakamoto Kazuya Nakagawa Shuichi Hayashi Naoki Harada Ryoichi Yamaji Yoshihisa Nakano Hiroshi Inui 《Food chemistry》2011
Eucalyptus leaf extract (ELE) is rich in hydrolyzable tannins. We examined the effects of ELE and its constituents on lipopolysaccharide (LPS)-induced liver injury in mice. Mice fed a diet supplemented with 1% ELE were intraperitoneally administered LPS. Six hours later, the serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities were significantly lower in the ELE-supplemented mice than in the controls; LPS-induced hepatic inducible nitric oxide synthase (iNOS) expression was also suppressed. ELE lowered LPS-stimulated iNOS expression in cultured RAW 264.7 macrophages. Furthermore, the aglycones of hydrolyzable tannins, gallic acid (GA) and ellagic acid (EA), inhibited iNOS induction to a greater extent than did ELE (15-fold higher). When mice were fed a 1% GA or EA diet, the increase in the serum ALT and AST activities and hepatic iNOS expression in response to the LPS challenge were significantly attenuated. Thus, hydrolyzable tannins in ELE ameliorate LPS-induced liver injury. 相似文献