全文获取类型
收费全文 | 796篇 |
免费 | 10篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 61篇 |
综合类 | 2篇 |
化学工业 | 195篇 |
金属工艺 | 10篇 |
机械仪表 | 19篇 |
建筑科学 | 15篇 |
能源动力 | 19篇 |
轻工业 | 70篇 |
水利工程 | 3篇 |
无线电 | 58篇 |
一般工业技术 | 132篇 |
冶金工业 | 113篇 |
原子能技术 | 26篇 |
自动化技术 | 86篇 |
出版年
2022年 | 11篇 |
2021年 | 11篇 |
2020年 | 9篇 |
2019年 | 6篇 |
2018年 | 11篇 |
2017年 | 5篇 |
2016年 | 14篇 |
2015年 | 8篇 |
2014年 | 7篇 |
2013年 | 40篇 |
2012年 | 32篇 |
2011年 | 49篇 |
2010年 | 25篇 |
2009年 | 32篇 |
2008年 | 27篇 |
2007年 | 33篇 |
2006年 | 22篇 |
2005年 | 38篇 |
2004年 | 26篇 |
2003年 | 30篇 |
2002年 | 21篇 |
2001年 | 16篇 |
2000年 | 16篇 |
1999年 | 21篇 |
1998年 | 54篇 |
1997年 | 36篇 |
1996年 | 21篇 |
1995年 | 11篇 |
1994年 | 16篇 |
1993年 | 13篇 |
1992年 | 10篇 |
1991年 | 13篇 |
1990年 | 4篇 |
1989年 | 12篇 |
1988年 | 7篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 11篇 |
1983年 | 11篇 |
1982年 | 12篇 |
1980年 | 8篇 |
1979年 | 4篇 |
1977年 | 4篇 |
1976年 | 7篇 |
1975年 | 4篇 |
1973年 | 3篇 |
1971年 | 3篇 |
1968年 | 2篇 |
1967年 | 2篇 |
排序方式: 共有809条查询结果,搜索用时 15 毫秒
101.
Morita N Takamura N Ashizawa K Shimasaki T Yamashita S Okumura Y 《Radiation protection dosimetry》2005,113(3):326-329
To understand the current situation of internal radiation exposure in the population around the Chernobyl Nuclear Power Plant (CNPP), we examined the 137Cs body burden in six residents of Belarus, Ukraine and Russia in 2002 and 2004 using the whole-body counter (WBC) at Nagasaki University (Japan). The data were compared with those of our previous study performed in 1993-1994 using the same method. In 2002 and 2004, peaks of 137Cs were detected in two residents from Gomel, which was heavily contaminated by the CNPP accident, one from Minsk (Belarus) and one from Kiev (Ukraine), but another resident from Minsk showed no 137Cs peaks. The results of the present study suggests that residents around the CNPP are still exposed to chronic 137Cs internal irradiation, probably due to the daily consumption of contaminated domestic foods, but the risk of any disease by the irradiation is quite low. Long-term follow-up of WBC around the CNPP is useful and may contribute to radiation safety regulation together with a reduction of unnecessary radiophobia for the residents. 相似文献
102.
Toshio Oishi Morinori Kamuo Katsutoshi Ono Joichiro Moriyama 《Metallurgical and Materials Transactions B》1983,14(1):101-104
The thermodynamic properties of silica-saturated iron silicate slags in equilibrium with liquid copper have been studied from oxygen partial pressure measurements in the temperature range from 1490 to 1580 K by means of a solid electrolyte galvanic cell. The following cells were used: Pt, Ni-NiO/O=/slag-Cu(l), Cr2O3, Pt; Pt, Fe-FeO/O=/slag-Cu(Fe sat.), Fe. A strong correlation was found between oxygen pressure and the copper content of the slag; the copper content increased from less than 1 pct near iron saturation to about 4 pct at an oxygen partial pressure of 7.2 x 10?3 Pa. A similar correlation was found between the ferric iron/total iron ratio and the oxygen pressure. The oxygen content in liquid copper decreased with increasing iron content in liquid copper and increased slightly near iron saturation. This behavior could be explained qualitatively by using the standard free energy of formation of FeO and the activities of components. 相似文献
103.
Noboru Kikuchi 《Computer Methods in Applied Mechanics and Engineering》1983,37(1):109-123
Three-node triangular elements obtained from the intersecting diagonals of quadrilaterals are thoroughly investigated for the penalty method formulation of incompressible problems such as Stokes flow, Navier-Stokes flow, and small-deformation rubber elasticity. Equivalence of the present formulation to the one using 4-node quadrilateral isoparametric elements with selective reduced integration, is presented. Convergence, instability phenomenon, smoothing of the pressure distribution are studied together with decompositions into triangular elements. 相似文献
104.
105.
Noboru Yamazaki Seiichi Nakahama Akira Hirao Juheiji Kawabata Hiromichi Noguchi Yasuzo Uchida 《Polymer Bulletin》1980,2(4):269-274
Summary Catalysis of cationic polyelectrolytes for the decarboxylation of 6-nitrobenzisoxazole-3-carboxylate anion was studied in a buffer solution (pH=9.0). Cross-linked poly (4-vinylpyridinium) salts prepared from 4-vinylpyridine and , -dibromides were used as cationic catalysts. The cross-linked catalysts were found to accelerate markedly the decarboxylation in comparison with the linear water-soluble analogues. Effect of the polymer structure such as the length of (CH2)x linkages between positive charges on the catalytic activity was examined. It was suggested that the acceleration by the cross-linked polymer catalysts would be due to the hydrophobic microenvironment around the catalytic sites. 相似文献
106.
107.
The thickness of the glass substrate used in liquid crystal displays continues to be decreased from its original thickness of 1.1 mm for the purpose reducing size and weight. The aim of this study was to clarify the influence of the glass substrate thickness during laser scribing with crack propagation caused by laser heating followed by quick quenching. The laser scribe conditions for soda-lime glass substrates with thickness equal to or less than 1.1 mm were obtained in laser irradiation experiments. Two-dimensional thermal elasticity analysis was conducted with a finite element method based on the scribable conditions obtained in the experiment. The laser scribable conditions can then be estimated by the upper limit of the maximum surface temperature, Tmax, and the lower limit of the maximum tensile stress, σtmax, in the cooling area, regardless of the glass substrate thickness. There is a substrate thickness with which the maximum tensile stress σtmax becomes the largest under each scribe condition. The substrate thickness with which σtmax becomes the largest is obtained at a faster scribe velocity for thinner glass substrate and at slower scribe velocity for thicker glass substrate. Owing to these relations, the crack depth also has almost the same tendency as σtmax. 相似文献
108.
Yuki Hirai Hirosato Monobe Norihiro Mizoshita Masaya Moriyama Kenji Hanabusa Yo Shimizu Takashi Kato 《Advanced functional materials》2008,18(11):1668-1675
Discotic liquid‐crystalline (LC) physical gels have been prepared by combining the self‐assembled fibers of a low‐molecular‐weight gelator and semiconducting LC triphenylene derivatives. The hole mobilities of the discotic LC physical gels measured by a time‐of‐flight method become higher than those of LC triphenylenes alone. The introduction of the finely dispersed networks of the gelator in the hexagonal columnar phases may affect the molecular dynamics of the liquid crystals, resulting in the enhancement of hole transporting behavior in the LC gel state. 相似文献
109.
Pseudomonas aeruginosa as a model microorganism for investigation of chemotactic behaviors in ecosystem 总被引:1,自引:0,他引:1
Kato J Kim HE Takiguchi N Kuroda A Ohtake H 《Journal of Bioscience and Bioengineering》2008,106(1):1-7
Motile bacteria sense changes in the concentration of chemicals in environments and respond in a behavioral manner. This behavioral response is called chemotaxis. Bacterial chemotaxis can be viewed as an important prelude to metabolism, prey-predator relationships, symbiosis, infections, and other ecological interactions in biological communities. Genome analysis reveals that a large number of environmental motile bacteria possess a number of genes involved in chemosensing and chemotatic signal transduction. Pseudomonas aeruginosa has a very complex chemosensory system with more than 20 chemotaxis (che) genes in five distinct clusters and 26 chemoreceptor (methyl-accepting chemotaxis protein [mcp]) genes. Among the 26 MCPs of P. aeruginosa, nine have been identified as MCPs for amino acids, inorganic phosphate, oxygen, ethylene, and volatile chlorinated aliphatic hydrocarbons, whereas 3 MCPs were demonstrated to be involved in biofilm formation and biosynthesis of type IV pilus. Six che genes are essential for chemotactic responses, while genes in Pil-Chp cluster and Wsp cluster are involved in type IV pilus synthesis and twitching motility and biofilm formation, respectively. P. aeruginosa, with its complex chemotaxis system, is a better model microorganism for investigating ecological aspects of chemotaxis in environmental bacteria than Escherichia coli and Salmonella enterica serovar Typhimurium, which possess a relatively simpler chemotaxis system. 相似文献
110.
Kazuko Iwamoto Shinichi Matsumura Yuri Yoshioka Ayami Yamamoto Shohei Makino Tatsuya Moriyama Nobuhiro Zaima 《Lipids》2019,54(5):311-320
Accumulation of amyloid-β peptide is associated with Alzheimer's dementia. Previously, we reported that sesamin and sesamolin inhibited β-secretase activity in vitro, and each was transported to the serum and brain in mice after oral administration. However, the bioavailability of sesamin and sesamolin was poor in mice. In this study, we aimed to improve the bioavailability of sesamin and sesamolin. We found that the levels of sesamin and sesamolin in mouse serum and brain were higher after the administration of a mixture of sesame extract and turmeric oil (MST) than those after administering sesame extract alone. Serum sesamin and sesamolin contents in the MST-treated group were 23-fold and 15-fold higher, respectively, than those in the sesame extract-treated group. Brain sesamin and sesamolin contents in the MST-treated group were 14-fold and 11-fold higher, respectively, than those in the sesame extract-treated group. These results suggest that turmeric oil is an effective solvent to enhance the bioavailability of sesamin and sesamolin. 相似文献