全文获取类型
收费全文 | 567篇 |
免费 | 5篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 44篇 |
综合类 | 8篇 |
化学工业 | 232篇 |
金属工艺 | 15篇 |
机械仪表 | 10篇 |
建筑科学 | 10篇 |
能源动力 | 34篇 |
轻工业 | 24篇 |
水利工程 | 1篇 |
无线电 | 41篇 |
一般工业技术 | 83篇 |
冶金工业 | 31篇 |
原子能技术 | 20篇 |
自动化技术 | 21篇 |
出版年
2022年 | 4篇 |
2021年 | 8篇 |
2019年 | 3篇 |
2018年 | 6篇 |
2016年 | 5篇 |
2015年 | 7篇 |
2014年 | 7篇 |
2013年 | 15篇 |
2012年 | 20篇 |
2011年 | 25篇 |
2010年 | 14篇 |
2009年 | 23篇 |
2008年 | 16篇 |
2007年 | 19篇 |
2006年 | 21篇 |
2005年 | 12篇 |
2004年 | 12篇 |
2003年 | 22篇 |
2002年 | 21篇 |
2001年 | 12篇 |
2000年 | 10篇 |
1999年 | 20篇 |
1998年 | 20篇 |
1997年 | 11篇 |
1996年 | 14篇 |
1995年 | 19篇 |
1994年 | 15篇 |
1993年 | 12篇 |
1992年 | 11篇 |
1991年 | 7篇 |
1990年 | 8篇 |
1989年 | 6篇 |
1988年 | 2篇 |
1987年 | 16篇 |
1986年 | 12篇 |
1985年 | 15篇 |
1984年 | 14篇 |
1983年 | 10篇 |
1982年 | 7篇 |
1981年 | 13篇 |
1980年 | 7篇 |
1979年 | 16篇 |
1978年 | 10篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 6篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1968年 | 2篇 |
排序方式: 共有574条查询结果,搜索用时 125 毫秒
101.
Application of microbial genes to recalcitrant biomass utilization and environmental conservation 总被引:3,自引:0,他引:3
Recent papers concerning the application of microbial genes to recalcitrant biomass utilization and environmental conservation are reviewed. Microbial genes have been integrated and expressed in plants and microorganisms. When cellulose-degrading enzyme genes are expressed in rice plants, the transgenic plants exhibit swollen cell walls which increases the digestibility of rice straw in the rumen. When genes encoding aromatic compound-degrading enzymes are expressed in plants, it is expected that aromatic compounds contaminating soil would be degraded during the growth of the transgenic plants. The former transgenic plants are utilized as feed and the latter for phytoremediation. Dockerin and cohesin interactions occurring in the cellulase complex, cellulosome, are applied to the construction of artificial enzyme complexes and protein purification by expressing the genes in transformed bacteria and/or silkworms, respectively. In the case of the forced expression of bacterial genes encoding chitinase and/or hydrogenase in the wild-type bacteria, chitin degradation and hydrogen gas production in the transformed bacteria occur at much higher rates than in the wild type. 相似文献
102.
103.
We report here a simple method to identify the ‘emerging topics’ in life sciences. First, the keywords selected from MeSH
terms on PubMed by filtering the terms based on their increment rate of the appearance, and, then, were sorted into groups
dealing with the same topics by ‘co-word’ analysis. These topics were defined as ‘emerging topics’. The survey of the emerging
keywords with high increment rates of appearance between 1972 to 2006 showed that emerging topics changed dramatically year
by year, and that the major shift of the topics occurred in the late 90s; the topics that cover technical and conceptual aspects
in molecular biology to the more systematic ‘-omics’-related and nanoscience-related aspects. We further investigated trends
in emerging topics within various sub-fields in the life sciences. 相似文献
104.
Limited resources of fossil energy require the search for new energy conversion processes and the increase of the efficiency
of power plants to ensure the energy household in the future. Basically, changing the combustion mode from steady to pulse
combustion makes an enormous reduction of fuel consumption possible. Active control systems for pulse combustors installed
into the inlet further improve the efficiency and extend the operating range considerably. The control algorithm including
fuel rate - air rate - pressure characteristics and control strategies as well are presented. 相似文献
105.
Masaru Watanabe Makoto Mochiduki Shuhei Sawamoto Tadafumi Adschiri Kunio Arai 《The Journal of Supercritical Fluids》2001,20(3):2612
In this study, we show the results of partial oxidation experiments of n-hexadecane (n-C16) and polyethylene (PE) in supercritical water (SCW). The experiments were carried out at 673 or 693 K of reaction temperature and 5 or 30 min of reaction time using a 6 cm3 of a batch type reactor. Water density ranged from 0.1 to 0.52 g/cm3 (water pressure: 20–40 MPa). The loaded amount of oxygen was set to 0.3 of the ratio of oxygen atom to carbon atom. Some experiments were made using CO instead of oxygen for the partial oxidation of n-C16 and PE to explore the effect of water gas shift reaction. In the results of partial oxidation of n-C16, the yield of CO and some compounds containing oxygen atoms, such as aldehydes and ketones increased with increasing water density. Moreover, 1-alkene/ n-alkane ratio in the products decreased with increasing water density. The 1-alkene/n-alkane ratio was lower than that of pyrolysis in SCW. Also for the case of PE experiments, in dense SCW (0.42 g/cm3), the 1-alkene/n-alkane ratio in partial oxidation was lower than that in SCW pyrolysis. In the case of CO experiments for n-C16 and PE, 1-alkene/n-alkane ratio was a little lower than that of pyrolysis in SCW. These results show that the yield of n-alkane, which is a hydrogenated compound, was higher through water gas shift reaction in SCW and also through partial oxidation in SCW. Therefore, these results suggest the possibility of hydrogenation of hydrocarbon through partial oxidation followed by the water gas shift reaction. 相似文献
106.
Asep Bustanil Aripin Takashi Yamamoto Makoto Nishi Kunio Hayakawa 《Polymer-Plastics Technology and Engineering》2020,59(12):1308-1316
ABSTRACTCarbon fiber reinforced thermoplastic (CFRTP) has a good electromagnetic shielding property due to its higher conductivity and broad absorption frequency bandwidth while presenting high specific strength and stiffness, their easy process-ability, cost-effectiveness, and recyclability. In the present study, laminated CFRTP made of carbon fiber-polyamide 6 unidirectional tape (UD tape) were fabricated with different laminate configurations and arrangements (unidirectional, bidirectional, and quasi–isotropic) and then were compared with randomly chopped-tape CFRTP. Thereafter, estimated electromagnetic interference shielding effectiveness (EMI-SE) using Simon formalism and flexural properties of CFRTP were evaluated. The result showed a remarkable total EMI-SE of 31–44 dB in the Ultra High Frequency (UHF) range and strongly correlated with the laminate configuration of CFRTP. Whereas, randomly chopped-tape CFRTP has a lower total EMI-SE of 23–27 dB in the same frequency range. In addition, the flexural test result showed the flexural strength and modulus are strongly influenced by the tape layer configuration in the laminated CFRTP. Moreover, microscopy analysis was also conducted to verify the interlaminar structure and fiber-to-fiber contact in the composite. In conclusion, laminated CFRTP made of UD tape can be considered as electromagnetic interference shielding material for both functional and structural applications. 相似文献
107.
108.
The effect of chlorphentermine (CP) treatment (50 mg/kg/ day, per os [po]) on the incorporation of [14C]choline into rat lung phospholipid was studied.Total phospholipid content was increased 2.0-fold and 1.7-fold after seven
and 14 days, respectively, compared with the pair-fed rats. The incorporation of [14C]choline into phosphatidylcholine (PC) was significantly inhibited by either seven or 14 days of CP treatment. Nevertheless,
the PC content was significantly increased by day 7 and stayed elevated at day 14 of CP treatment. Choline and phosphorylcholine
contents were significantly decreased by the CP treatment. These results suggest that the higher accumulation of PC is due
to inhibition of enzymes involved in the hydrolysis of phospholipids rather than to a stimulation of the phospholipid synthesis.
Presented in part at the SOT Meeting, Atlanta, GA, March 1984 (abstracted inThe Toxicologist 4[1], 64). 相似文献
109.
Kunio Ishikawa Shozo Takagi Laurence C. Chow Yoshiko Ishikawa 《Journal of materials science. Materials in medicine》1995,6(9):528-533
The setting time of a calcium phosphate cement consisting of tetracalcium phosphate (TTCP) and dicalcium phosphate anhydrous (DCPA) was reduced from 30 to 5 min by use of a cement liquid that contained a phosphate concentration of 0.25 mol/l or higher. The diametral tensile strength and conversion of the cement ingredients to hydroxyapatite (OHAp) during the first 3 h were also significantly increased by the phosphate. However, the phosphate produced no significant effects on the properties of the 24-h cement samples. Results from additional experiments in a slurry system verified that the high phosphate concentration in the solution accelerated the formation of OHAp in the TTCP + DCPA system, and this reaction could explain the fast-setting properties of the cements.Certain commercial materials and equipment are identified in this paper to specify the experimental procedure. In no instance does such identification imply recommendation or endorsement by the American Dental Association or National Institute of Standards and Technology or that the materials or equipment identified is necessarily the best available for the purpose. 相似文献
110.
Ohnishi Kouhei Ueda Youzou Miyachi Kunio 《Industrial Electronics, IEEE Transactions on》1986,(3):217-223
The paper deals with a compensation method of the rotor-resistance variation in induction motor drives using high-performance slip-frequency control. Our proposed method is based on a discrete-type model reference adaptive system (MRAS), and it is implemented in an 8086 microprocessor. When an induction motor is driven by a controlled current source, the system sensitivity to the rotor resistance variation is increased. In the MRAS, the value of the rotor resistance is estimated and the slip-frequency gain is adjusted. Experimental and numerical results show that even if the value of the rotor resistance varies from its nominal value, the secondary flux level is maintained constant by using this compensation method. These results point out the validity of our proposed method. 相似文献