全文获取类型
收费全文 | 890篇 |
免费 | 22篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 31篇 |
综合类 | 4篇 |
化学工业 | 256篇 |
金属工艺 | 29篇 |
机械仪表 | 9篇 |
建筑科学 | 11篇 |
能源动力 | 69篇 |
轻工业 | 78篇 |
水利工程 | 3篇 |
石油天然气 | 2篇 |
无线电 | 79篇 |
一般工业技术 | 174篇 |
冶金工业 | 82篇 |
原子能技术 | 19篇 |
自动化技术 | 70篇 |
出版年
2022年 | 5篇 |
2021年 | 20篇 |
2020年 | 13篇 |
2019年 | 12篇 |
2018年 | 13篇 |
2017年 | 9篇 |
2016年 | 13篇 |
2015年 | 12篇 |
2014年 | 39篇 |
2013年 | 45篇 |
2012年 | 49篇 |
2011年 | 53篇 |
2010年 | 45篇 |
2009年 | 49篇 |
2008年 | 47篇 |
2007年 | 48篇 |
2006年 | 52篇 |
2005年 | 34篇 |
2004年 | 24篇 |
2003年 | 22篇 |
2002年 | 27篇 |
2001年 | 20篇 |
2000年 | 9篇 |
1999年 | 12篇 |
1998年 | 36篇 |
1997年 | 20篇 |
1996年 | 17篇 |
1995年 | 12篇 |
1994年 | 9篇 |
1993年 | 11篇 |
1992年 | 13篇 |
1991年 | 16篇 |
1990年 | 13篇 |
1989年 | 11篇 |
1988年 | 6篇 |
1987年 | 9篇 |
1986年 | 8篇 |
1985年 | 11篇 |
1984年 | 6篇 |
1983年 | 8篇 |
1982年 | 2篇 |
1981年 | 6篇 |
1979年 | 2篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1973年 | 4篇 |
1972年 | 3篇 |
1970年 | 3篇 |
排序方式: 共有916条查询结果,搜索用时 402 毫秒
61.
Cytochrome c oxidase activity in preosteoclasts induced by experimental tooth movement 总被引:1,自引:0,他引:1
Cytochrome c oxidase activity was detected in preosteoclasts induced by experimental tooth movement. Mitochondria with reaction products of the enzyme in the inner membrane and outer compartment, which we classified as type 1 mitochondria, were observed in preosteoclasts. The number of type 1 mitochondria in the preosteoclasts, however, was distinctly fewer as compared with those in active osteoclasts described in our previous studies. Also, some of preosteoclasts adjacent to the bone surface contained more type 1 mitochondria than preosteoclasts separated from the bone surface. These results suggest that cytochrome c oxidase activity is closely related to functional differentiation of preosteoclasts, and additionally can be used as an indicator of functional differentiation from preosteoclast to osteoclast. 相似文献
62.
One thousand two hundred cycles of accelerated exposure experiment with combined salt water spray simulating atmospheric corrosion was performed for investigating the effect of weld line direction and paint orientation on the corrosion and paint deterioration characteristics of welded part of the steel. The corrosion depth of the weld toe of transverse weld line became 1.35 times as large as that of the base metal part because of the remained salt water on the weld toe. The coating thickness at the weld toe became thin by vertically painting on the transverse weld line. When the scribe line was installed at the thin painted weld toe under the transverse weld line, the paint blister area became 15% larger than that of the base metal part. The paint coating thickness at the weld toe in different weld line directions and paint orientations should be confirmed and ensured from the viewpoints of manufacturing and maintaining steel structures. 相似文献
63.
Hideyuki Nakano Toru Takahashi Takahiro Tanino Yasuhiko Shirota 《Dyes and Pigments》2010,84(1):102-107
Novel azobenzene-based photo-responsive amorphous molecular materials, 4-[bis(9,9-dimethylfluoren-2-yl)amino]-4′-cyanoazobenzene and 4-[bis(9,9-dimethylfluoren-2-yl)amino]-4′-nitroazobenzene, have been synthesized and the formation of surface relief grating on their amorphous films has been investigated. It was found that a relatively large surface relief grating could be inscribed on both amorphous films upon interference exposure to the writing laser beams. The modulation depth of the surface relief grating inscribed on the amorphous film of the cyano-substituted material was found to be larger than that inscribed on the film of the nitro-substituted one and seemed to be comparable to that inscribed on the amorphous film of the parent material, 4-[bis(9,9-dimethylfluoren-2-yl)amino]azobenzene. These results were discussed from the viewpoint of their trans–cis photoisomerizations as amorphous films and glass-transition temperatures. 相似文献
64.
Effect of cellular inositol content on ethanol tolerance of Saccharomyces cerevisiae in sake brewing
The effect of cellular inositol content on the ethanol tolerance of sake yeast was investigated. In a static culture of strain K901 in a synthetic medium, when cells were grown in the presence of inositol in limited amount (L-cells), the inositol content of cells decreased by one-third that of cells grown in the presence of inositol in sufficient amount (H-cells). L-cells exhibited a higher death rate constant than H-cells in the presence of 12-20% ethanol, while no difference in specific ethanol production rate in the presence of 0-18% ethanol between the two cell types was observed. L-cells leaked more intracellular components, such as nucleotides, phosphate and potassium, in the presence of ethanol than H-cells. L-cells exhibited a lower intracellular pH value than H-cells, which represented the lowering of cell vitality by the decrease in H(+) extrusion activity. Furthermore, the plasma membrane H(+)-ATPase activity of L-cells was approximately one-half of that of H-cells. Therefore, it was considered that the decrease in viability in the presence of ethanol due to inositol limitation results from the lowering of H(+)-ATPase activity, which maintains the permeability barrier of the yeast membrane, ensuring the homeostasis of ions in the cytoplasm of yeast cells. It is assumed that the lowering of H(+)-ATPase activity due to inositol limitation is caused by the change in lipid environment of the enzyme, which is affected by inositol-containing glycerophospholipids such as phosphatidylinositol (PI), because in the PI-saturated mixed micellar assay system, the difference in H(+)-ATPase activity between L- and H-cells disappeared. In the early stage of sake mash, inositol limitation lowers the ethanol tolerance due to the decrease in H(+)-ATPase activity as in static culture. In the final stage of sake mash, the disruption of the ino1 gene responsible for inositol synthesis, resulted in a decrease in cell density. Furthermore, the ino1 disruptant, which was not capable of increasing the cellular inositol level in the final stage, exhibited a significantly higher methylene blue-staining ratio than the parental strain. It was suggested that the yeast cellular inositol level is one of the important factors which contribute to the high ethanol tolerance implied by the increased cell viability in the presence of ethanol. 相似文献
65.
Tomoya Nagira Hideyuki Yasuda Takumi Sakimura Kentarou Yoshida 《Journal of the European Ceramic Society》2012,32(10):2137-2143
It has been reported that solidification of the Al2O3–YAG equilibrium eutectic structure follows melting of the Al2O3–YAP metastable eutectic structure. Since the exothermic heat due to solidification was consumed by the endothermic heat due to melting, a fine and uniform eutectic structure was obtained. However, the composition of the Al2O3–YAG eutectic structure is restricted to the metastable eutectic composition. In this paper, Al2O3–YAG eutectic compacts with an off-metastable eutectic composition were prepared by the addition of Al2O3 particles to Al2O3–YAP eutectic particles with diameters less than 20 μm. In compositions ranging from 18.5 mol%Y2O3 to 13.5 mol%Y2O3, dense Al2O3–YAG eutectic compacts were formed without any Al2O3 segregation. The flexural strength and the fracture toughness remained almost unchanged with the increase in the Al2O3 phase. The addition of Al2O3 particles to the Al2O3–YAP eutectic particles enabled the matrix phase to change from the YAG phase to the Al2O3 phase. 相似文献
66.
Takashi Minemoto Shunichi Fukushige Hideyuki Takakura 《Solar Energy Materials & Solar Cells》2009,93(6-7):1062-1065
Differences in the outdoor performances of bulk (multi- and single-crystalline Si) and thin-film (amorphous Si(a-Si), a-Si/micro-crystalline Si and a-Si/a-SiGe/a-SiGe) photovoltaic (PV) modules are analyzed. The influence of module temperature and solar spectrum distribution on the PV output is clarified. The PV outputs almost only depend on module temperature in bulk-type Si PV modules while that depend both module temperature and spectrum distribution in thin-film ones. Also, the PV outputs of the bulk-type Si PV modules at most frequent condition at outdoor are lower than that at the standard test condition; in contrast, it was the other way round for thin-film ones. 相似文献
67.
Song Yu Guo Shuxiang Yin Xuanchun Zhang Linshuai Wang Yu Hirata Hideyuki Ishihara Hidenori 《Microsystem Technologies》2018,24(2):909-918
Microsystem Technologies - In this paper, a magnetorheological (MR) fluids based haptic interface has been developed in master site to provide the haptic sensation to the interventionalist during... 相似文献
68.
Sea urchin shells are generally discarded as food waste after removal of edible gonads, although they possess significant amount of polyhydroxylated naphtoquinone pigments having potent antioxidant property. In this study, separation and quantification of the pigment mixtures from purple sea urchin shells were performed using a C18 reversed-phase HPLC with isocratic elution of 50% mixture of solvent (A) formic acid: water (0.1: 100, v/v) and solvent (B) MeOH: acetonitrile (5: 9, v/v) at a flow rate of 0.5 mL/min. The pigment mixtures were separated into four major peaks in 30 min, which assumed to be spinochromes A, B and C and echinochrome A on the basis of UV-Vis absorption spectra obtained by a diode array detector. LC-MS analysis also supported these results by producing the predominant base peaks at m/z 221.1, 279.1, 265.1, and 263.1 corresponding to the pseudomolecular ions [M-H]− of the respective compounds. The HPLC method also showed good correlations (r2 > 0.98) between injected amounts of these pigments and peak areas recorded at 340 and 520 nm. These results indicated that the HPLC method developed in this study would be applicable for the separation and quantification of these major pigments in sea urchin shells. 相似文献
69.
A lower bound for the determinant of the solution to the Lyapunov matrix differential equation is derived. It is shown that this bound is obtained as a solution to a simple scalar differential equation. In the limiting case where the solution to the Lyapunov differential equation becomes stationary, the result reduces to one of the existing bounds for the algebraic equation. 相似文献
70.