全文获取类型
收费全文 | 753篇 |
免费 | 23篇 |
专业分类
电工技术 | 51篇 |
化学工业 | 188篇 |
金属工艺 | 4篇 |
机械仪表 | 12篇 |
建筑科学 | 14篇 |
能源动力 | 28篇 |
轻工业 | 51篇 |
水利工程 | 2篇 |
无线电 | 59篇 |
一般工业技术 | 138篇 |
冶金工业 | 115篇 |
原子能技术 | 15篇 |
自动化技术 | 99篇 |
出版年
2023年 | 10篇 |
2022年 | 17篇 |
2021年 | 17篇 |
2020年 | 9篇 |
2019年 | 11篇 |
2018年 | 13篇 |
2017年 | 14篇 |
2016年 | 21篇 |
2015年 | 15篇 |
2014年 | 27篇 |
2013年 | 47篇 |
2012年 | 41篇 |
2011年 | 41篇 |
2010年 | 39篇 |
2009年 | 34篇 |
2008年 | 36篇 |
2007年 | 32篇 |
2006年 | 15篇 |
2005年 | 22篇 |
2004年 | 17篇 |
2003年 | 22篇 |
2002年 | 19篇 |
2001年 | 12篇 |
2000年 | 8篇 |
1999年 | 21篇 |
1998年 | 44篇 |
1997年 | 33篇 |
1996年 | 14篇 |
1995年 | 19篇 |
1994年 | 9篇 |
1993年 | 15篇 |
1992年 | 8篇 |
1991年 | 6篇 |
1990年 | 7篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 7篇 |
1982年 | 2篇 |
1981年 | 7篇 |
1980年 | 1篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 6篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1971年 | 2篇 |
排序方式: 共有776条查询结果,搜索用时 296 毫秒
101.
Otsubo K. Matsuda M. Takada K. Okumura S. Ekawa M. Tanaka H. Ide S. Mori K. Yamamoto T. 《Electronics letters》2008,44(10):631-632
Uncooled 25 Gbit/s direct modulation of 1.3 mum DFB lasers is demonstrated. The 150 mum-long semi-insulating buried-heterostructure AIGalnAs quantum-well DFB lasers show clear eye-openings with dynamic extinction ratio of 5 dB up to 70degC. 13 km singlemode-fibre transmission experiments using the devices show low power penalty within 1.3 dB between 25 and 70degC. These characteristics are the first achievement by 1.3 mum directly modulated lasers. 相似文献
102.
Que Dan Nguyen Kosuke Kikuchi Basudev Maity Takafumi Ueno 《International journal of molecular sciences》2021,22(4)
Protein assemblies provide unique structural features which make them useful as carrier molecules in biomedical and chemical science. Protein assemblies can accommodate a variety of organic, inorganic and biological molecules such as small proteins and peptides and have been used in development of subunit vaccines via display parts of viral pathogens or antigens. Such subunit vaccines are much safer than traditional vaccines based on inactivated pathogens which are more likely to produce side-effects. Therefore, to tackle a pandemic and rapidly produce safer and more effective subunit vaccines based on protein assemblies, it is necessary to understand the basic structural features which drive protein self-assembly and functionalization of portions of pathogens. This review highlights recent developments and future perspectives in production of non-viral protein assemblies with essential structural features of subunit vaccines. 相似文献
103.
Hiroyuki Koide Satoshi Hirano Takafumi Ide Kazuhiro Saito Hikaru Suzuki Go Yasuno Yoshitaka Hamashima Sei Yonezawa Naoto Oku Tomohiro Asai 《Advanced functional materials》2021,31(3):2005641
Protein affinity reagents (e.g., antibodies) are often used for basic research, diagnostics, separations, and disease therapy. Although a lot of “synthetic” protein affinity reagents have been developed as a cost-effective alternative to antibodies, their low biocompatibility is a considerable problem for clinical application. Lipid nanoparticles (LNP) represent a highly biocompatible drug delivery agent. However, little has been reported that LNP itself works as a protein affinity reagent in living animals. Here, LNP is engineered for binding to and neutralizing a target toxic peptide in living animals by multifunctionalization with amino acid derivatives. Multifunctionalized LNP (MF-LNP) is prepared using amino acid derivative-conjugated lipids. Optimized MF-LNP exhibits nanomolar affinity to the target toxic peptide and inhibits toxic peptide-dependent hemolysis and cytotoxicity. In addition, MF-LNP captures and neutralizes the toxic peptide after intravenous injection in the bloodstream; in addition, MF-LNP does not release the toxic peptide in the accumulated organ. These results reveal the potential of using LNP as a highly biocompatible protein affinity reagent such as an antidote. 相似文献
104.
105.
Thermal desorption aerosol mass spectrometers (TDAMSs) with electron ionization are widely used for quantitative analysis of aerosol chemical composition, and the ionization efficiency of evolved gas molecules from aerosol particles is an important parameter for such analysis. We performed laboratory experiments using a custom-made TDAMS to investigate the key factors affecting ionization efficiency. Ammonium chloride (NH4Cl) and ammonium iodide (NH4I) were used as test compounds because their thermal decomposition products are expected to be simple (dominated by ammonia (NH3) and hydrogen halide (HX)). The ion signals originating from NH3 and HX were measured by altering the position of the ionizer relative to the vaporization point. The ratio of ion signal from NH3 to that from HX increased with increasing divergence angle of evolved gas plumes, which suggests that the angular distribution of gas molecules could be an important factor affecting the ionization efficiency.
Copyright © 2018 American Association for Aerosol Research 相似文献
106.
Masami Kojima Yukihisa Suzuki Kensuke Sasaki Masao Taki Kanako Wake Soichi Watanabe Maya Mizuno Takafumi Tasaki Hiroshi Sasaki 《Journal of Infrared, Millimeter and Terahertz Waves》2018,39(9):912-925
The objective of this study was to develop a model of ocular damage induced by 40, 75, and 95 GHz continuous millimeter waves (MMW), thereby allowing assessment of the clinical course of ocular damage resulting from exposure to thermal damage-inducing MMW. This study also examined the dependence of ocular damage on incident power density. Pigmented rabbit eyes were exposed to 40, 75, and 95 GHz MMW from a spot-focus-type lens antenna. Slight ocular damage was observed 10 min after MMW exposure, including reduced cornea thickness and reduced transparency. Diffuse fluorescein staining around the pupillary area indicated corneal epithelial injury. Slit-lamp examination 1 day after MMW exposure revealed a round area of opacity, accompanied by fluorescence staining, in the central pupillary zone. Corneal edema, indicative of corneal stromal damage, peaked 1 day after MMW exposure, with thickness gradually subsiding to normal. Three days after exposure, ocular conditions had almost normalized, though corneal thickness was slightly greater than that before exposure. The 50% probability of ocular damage (DD50) was in the order 40?>?95?≈?75 GHz at the same incident power densities. 相似文献
107.
Kastner Marc A. Ide Ichiro Nack Frank Kawanishi Yasutomo Hirayama Takatsugu Deguchi Daisuke Murase Hiroshi 《Multimedia Tools and Applications》2020,79(25-26):18167-18199
Multimedia Tools and Applications - Natural Language Processing and multi-modal analyses are key elements in many applications. However, the semantic gap is an everlasting problem, leading to... 相似文献
108.
Wen Shi Tian Song Takafumi Katayama Xiantao Jiang Takashi Shimamoto 《Journal of Real-Time Image Processing》2018,15(1):57-71
This paper proposes a downsampling information-based intra-coding scheme which consists of two parts, preprocessing stage and fast intra-coding stage. Three downsampling information-based fast decision algorithms are proposed in fast intra-coding stage. Moreover, a parallelized architecture for the proposed fast intra-coding scheme is proposed. The preprocessed downsampling stage can be executed with intra-coding stage in parallel. The proposed architecture fully makes use of this feature to improve the throughput and fragment data dependency. Experimental results demonstrate that the proposed algorithms achieves on average 60.4% reduction in encoding time with negligible coding efficiency loss, compared with original HEVC. 相似文献
109.
Yasunori Imada Takafumi Shido Ryuichiro Ohnishi Kiyoshi Isobe Masaru Ichikawa 《Catalysis Letters》1996,38(1-2):101-108
SiO2-impregnated complete and incomplete cubane-type molybdenum oxide clusters such as [(RhCp*)4Mo4O16] (I) and [(RhCp*)2Mo3O9(OMe)4] (II) were photoreduced with a UHP-Hg lamp (> 365 nm) in CO, resulting in the formation of catalytically active species for propene metathesis at 300 K. The CO-photoreduced Mo oxide clusters were characterized by EXAFS, IR, XPS and TPD technique. The results suggest that the Mo-O4c (four-centered bridging oxygens) in I were specifically reduced with CO under the illumination to produce two sets of subcarbonyl species, e.g., those characteristic of the IR bands at 2061 and 2021 cm–1, which were thermally inactive for the13CO exchange reaction but very active under illumination at 300 K, possibly assignable to Mo(CO)x (x = 2, 3), whereas those at 2092 and 2035 cm–1 due to Rh(CO)2, which were readily exchangeable with13CO at 300 K in dark. Removal of both carbonyls attached on Rh and Mo in photoreduced I and II by evacuation at 375–440 K led to the formation of oxygen-deficient Mo4+/Mo5+ sites, which exhibited high catalytic activities in propene metathesis at 300 K to produce an equimolar mixture of ethene and 2-butenes. The CO-photoreduced incomplete cubane Mo oxide cluster (II) exhibited higher activities and higher trans/cis ratios of 2-butenes in the reaction, compared with those on the photoreduced I. 相似文献
110.
Thermotropic liquid crystal polymers are a new class of polymeric materials that consist of rigid backbone molecules and thus, even in the quiescent condition, take extended chain conformation to form optically anisotropic melts. A systematic investigation was carried out on how this type of material responds to two basic flow fields: shear and elongation. Rheological properties of the polymer in these flow fields have also been measured. It was found that a high level of molecular orientation was readily obtained by elongational flow but not with shear flow. Specifically, extraordinarily high orientation was obtained when the melt was subjected to small elongational strains, whiel shear strain or shear rate had little effect. A possible mechanism to explain these behaviors is illustrated based on the existing observations or theories of rodlike molecules. This finding was used to interpret the orientation distribution in the extruded and injection-molded articles. 相似文献