全文获取类型
收费全文 | 973篇 |
免费 | 21篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 35篇 |
综合类 | 1篇 |
化学工业 | 232篇 |
金属工艺 | 25篇 |
机械仪表 | 41篇 |
建筑科学 | 21篇 |
能源动力 | 37篇 |
轻工业 | 64篇 |
水利工程 | 3篇 |
无线电 | 85篇 |
一般工业技术 | 224篇 |
冶金工业 | 116篇 |
原子能技术 | 22篇 |
自动化技术 | 91篇 |
出版年
2023年 | 4篇 |
2022年 | 17篇 |
2021年 | 15篇 |
2020年 | 5篇 |
2019年 | 9篇 |
2018年 | 8篇 |
2017年 | 19篇 |
2016年 | 8篇 |
2015年 | 14篇 |
2014年 | 15篇 |
2013年 | 47篇 |
2012年 | 36篇 |
2011年 | 39篇 |
2010年 | 36篇 |
2009年 | 39篇 |
2008年 | 62篇 |
2007年 | 52篇 |
2006年 | 45篇 |
2005年 | 44篇 |
2004年 | 22篇 |
2003年 | 37篇 |
2002年 | 34篇 |
2001年 | 30篇 |
2000年 | 20篇 |
1999年 | 15篇 |
1998年 | 48篇 |
1997年 | 31篇 |
1996年 | 37篇 |
1995年 | 27篇 |
1994年 | 16篇 |
1993年 | 20篇 |
1992年 | 10篇 |
1991年 | 11篇 |
1990年 | 7篇 |
1989年 | 11篇 |
1988年 | 8篇 |
1987年 | 7篇 |
1986年 | 9篇 |
1985年 | 14篇 |
1984年 | 6篇 |
1983年 | 10篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 10篇 |
1978年 | 5篇 |
1977年 | 3篇 |
1976年 | 8篇 |
1975年 | 3篇 |
1969年 | 3篇 |
1967年 | 2篇 |
排序方式: 共有997条查询结果,搜索用时 683 毫秒
1.
2.
Ichiro Hirosawa Tetsuo Honma Kazuo Kato Naoto Kijima Yasuo Shimomura 《Journal of the Society for Information Display》2004,12(3):269-273
Abstract— We studied the influence of annealing in air on doped europium in BaMgAl10O17 by performing x‐ray absorption fine‐structure measurements. We determined the oxidation of doped divalent europium by annealing in air at over 500°C. The interatomic distance between the europium and the surrounding oxygen atoms was compressed by oxidation. It also appears that the oxidation process of europium is determined by the diffusion of oxygen into BaMgAl10O17. 相似文献
3.
Photoinduced Formation of Small Gold Particles in Silica Gels 总被引:2,自引:0,他引:2
AuCl− 4 ions in sol-gel-derived silica gels (Au/silica gels) were photoreduced by ultraviolet light irradiation at room temperature. In the presence of ethylene glycol in the silica gels, small Au particles were effectively formed by the irradiation. When the storage temperature of the gels was increased in the dark after the irradiation, the surface plas-mon resonance absorption peak of the Au particles was shifted to longer wavelengths, indicating that the Au particles became large. At a storage temperature below 9°C, Au particles could not be observed in the silica gels. The apparent activation energy of Au particle formation was estimated to be 17. 3 kcal·tmol−1 . 相似文献
4.
5.
Yamaoka M. Shinozaki Y. Maeda N. Shimazaki Y. Kato K. Shimada S. Yanagisawa K. Osada K. 《Solid-State Circuits, IEEE Journal of》2005,40(1):186-194
An on-chip 1-Mb SRAM suitable for embedding in the application processor used in mobile cellular phones was developed. This SRAM supports three operating modes - high-speed active mode, low-leakage low-speed active mode, and standby mode - and uses a subdivisional power-line control (SPC) scheme. The combination of three operating modes and the SPC scheme realizes low-power operation under actual usage conditions. It operates at 300 MHz, with leakage of 25 /spl mu/A/Mb in standby mode, and 50 /spl mu/A/Mb at the low-leakage active mode. This SRAM also uses a self-bias write scheme that decreases of minimum operating voltage by about 100 mV. 相似文献
6.
Y Shinkai M Yoshimura M Morishima-Kawashima Y Ito H Shimada K Yanagisawa Y Ihara 《Canadian Metallurgical Quarterly》1997,42(6):899-908
To further investigate the process of amyloid beta-protein (Abeta) deposition, we determined, using sensitive enzyme immunoassays, the levels of Abeta40 and Abeta42 (Abetas) in the soluble and insoluble fractions of the leptomeninges (containing arachnoid mater and leptomeningeal vessels) and cerebral cortices from elderly control subjects showing various stages of Abeta deposition and from patients affected by Alzheimer's disease (AD). In both locations, insoluble Abeta levels were higher by orders of magnitude than soluble Abeta levels. Soluble Abeta levels in cortices were much lower than those in leptomeninges. In insoluble Abeta in the cortex, Abeta42 was by far the predominant species, and Abeta42 in AD cortices was characterized by the highest degree of modifications in the amino terminus. In contrast, this Abeta42 predominance was not observed in insoluble Abeta in the leptomeninges, which were found to be able to accumulate Abetas to an extent similar to that in the cortex, on a weight basis. The levels of insoluble Abeta in the leptomeninges or cortex generally correlated with the degree of cerebral amyloid angiopathy or the abundance of senile plaque, respectively. However, the presence of plaque-free cortical samples showing significant levels of insoluble Abeta42 suggests that biochemically detectable Abeta accumulation precedes immunocytochemically detectable Abeta deposition in the cortex. 相似文献
7.
Ureteral obstruction enhances eicosanoid production in cortical and medullary tubules of rat kidneys
We examined prostaglandin (PG) E2, 6-keto PGF1alpha, and thromboxane B2 (TxB2) production in cortical and medullary tubules from sham-operated control (SOC) rats and rats with bilateral ureteral obstruction (BUO) of 24 h duration. In SOC rats medullary tubules produced significantly greater amounts of the three eicosanoids than cortical tubules. Again, the production of PGE2, 6-keto PGF1alpha, and TxB2 by cortical and medullary tubules was significantly greater in BUO rats than in SOC rats. To elucidate the mechanisms involved, we examined the activity of phospholipase A2 (PLA2) reactive against phosphatidylcholine or phosphatidylethanolamine (PE), the activity of phospholipase C (PLC), and the levels of cyclooxygenase (COX) in cortical and medullary tubules from SOC and BUO rats. In SOC rats the activity of phosphatidylcholine-PLA2 and PE-PLA2, the activity of PLC, and the mass of COX were significantly greater in medullary tubules than in cortical tubules. On the other hand, the activity of PLC in membranes of cortical tubules and the activity of PE-PLA2 and PLC in membranes of medullary tubules, which were in active location, were significantly greater in BUO rats than in SOC rats. COX levels were also significantly greater in cortical and medullary tubules of BUO rats than in those of SOC rats. Thus, we indicate that medullary tubules from SOC rats have greater production of eicosanoids through increased activity of the PLA2 and PLC-COX pathway than cortical tubules from the same group of rats. Again, in rats with BUO, the tubular eicosanoid production may be enhanced via activation of the PLC-COX pathway in cortical tubules or through activation of the PE-PLA2 and PLC-COX pathway in medullary tubules. The enhanced production of tubular eicosanoids observed in rats with BUO may affect tubular function, particularly sodium and water reabsorption. 相似文献
8.
J Yanagisawa M Takahashi H Kanki H Yano-Yanagisawa T Tazunoki E Sawa T Nishitoba M Kamishohara E Kobayashi S Kataoka T Sato 《Canadian Metallurgical Quarterly》1997,272(13):8539-8545
Fas (APO-1/CD95), which is a member of the tumor necrosis factor receptor superfamily, is a cell surface receptor that induces apoptosis. A protein tyrosine phosphatase, Fas-associated phosphatase-1 (FAP-1), that was previously identified as a Fas binding protein interacts with the C-terminal 15 amino acids of the regulatory domain of the Fas receptor. To identify the minimal region of the Fas C-terminal necessary for binding to FAP-1, we employed an in vitro inhibition assay of Fas/FAP-1 binding using a series of synthetic peptides as well as a screen of random peptide libraries by the yeast two-hybrid system. The results showed that the C-terminal three amino acids (SLV) of human Fas were necessary and sufficient for its interaction with the third PDZ (GLGF) domain of FAP-1. Furthermore, the direct cytoplasmic microinjection of this tripeptide (Ac-SLV) resulted in the induction of Fas-mediated apoptosis in a colon cancer cell line that expresses both Fas and FAP-1. Since t(S/T)X(V/L/I) motifs in the C termini of several other receptors have been shown to interact with PDZ domain in signal transducing molecules, this may represent a general motif for protein-protein interactions with important biological functions. 相似文献
9.
This paper presents an application of digital signal processing to data acquired by the radio imaging method (RIM) that was adopted to measure moisture distribution inside the human body. RIM was originally developed for the mining industry; we are applying the method to a biomedical measurement because of its simplicity, economy, and safety. When a two‐dimensional image was constructed from the measured data, the method provided insufficient resolution because the wavelength of the measurement medium, a weak electromagnetic wave in a VHF band, was longer than human tissues. We built and measured a phantom, a model simulating the human body, consisting of two water tanks representing large internal organs. A digital equalizer was applied to the measured values as a weight function, and images were reconstructed that corresponded to the original shape of the two water tanks. As a result, a two‐dimensional image containing two individual peaks corresponding to the original two small water tanks was constructed. The result suggests the method was applicable to biomedical measurement by the assistance of digital signal processing. This technique may be applicable to home‐based medical care and other situations in which safety, simplicity, and economy are important. 相似文献
10.
Densification of silica gels by hydrothermal hot-pressing 总被引:1,自引:0,他引:1
K. Yanagisawa M. Nishioka K. Ioku N. Yamasaki 《Journal of Materials Science Letters》1993,12(14):1073-1075