全文获取类型
收费全文 | 330篇 |
免费 | 10篇 |
专业分类
电工技术 | 14篇 |
综合类 | 1篇 |
化学工业 | 109篇 |
金属工艺 | 4篇 |
机械仪表 | 7篇 |
建筑科学 | 7篇 |
能源动力 | 6篇 |
轻工业 | 105篇 |
水利工程 | 1篇 |
无线电 | 11篇 |
一般工业技术 | 35篇 |
冶金工业 | 18篇 |
原子能技术 | 3篇 |
自动化技术 | 19篇 |
出版年
2023年 | 2篇 |
2022年 | 7篇 |
2021年 | 18篇 |
2020年 | 3篇 |
2019年 | 8篇 |
2018年 | 5篇 |
2017年 | 6篇 |
2016年 | 11篇 |
2015年 | 4篇 |
2014年 | 16篇 |
2013年 | 12篇 |
2012年 | 23篇 |
2011年 | 19篇 |
2010年 | 9篇 |
2009年 | 17篇 |
2008年 | 14篇 |
2007年 | 10篇 |
2006年 | 13篇 |
2005年 | 12篇 |
2004年 | 13篇 |
2003年 | 11篇 |
2002年 | 7篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 5篇 |
1998年 | 15篇 |
1997年 | 7篇 |
1996年 | 9篇 |
1995年 | 1篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1979年 | 6篇 |
1976年 | 1篇 |
排序方式: 共有340条查询结果,搜索用时 31 毫秒
261.
Taichi Sotani Hiroko Iwakiri Hirotaka Yamada Noritaka Shimosaraya Yu Miyagi Fumio Sanda 《大分子材料与工程》2019,304(9)
The Sonogashira–Hagihara coupling polymerization of ferrocene‐containing l ‐phenylalanine‐derived optically active o‐, m‐, p‐substituted bis(iodophenylene) monomers 1o , 1m , 1p with 1,4‐diethynylbenzene ( 2 ) and 1,4‐diethynyl‐2,5‐bis[2‐(2‐methoxyethoxy)ethoxy]benzene ( 3 ) is carried out to obtain the corresponding polymers consisting of ferrocene, amino acid, and phenyleneethynylene moieties. In the solution state, poly( 1o ‐ 2 ), poly( 1o‐3 ), and poly( 1m ‐ 2 ) exhibit no circular dichroism (CD) signals in N,N‐dimethylformamide (DMF), while poly( 1m‐3 ), poly( 1p ‐ 2 ), and poly( 1p ‐ 3 ) exhibit CD signals assignable to the main chain chromophore, indicating the formation of certain chiral structures. In the solid state, poly( 1o ‐ 2 ), poly( 1o‐3 ), poly( 1m ‐ 2 ), and poly( 1m‐3 ) exhibit CD signals in the solid state, while poly( 1p ‐ 2 ), poly( 1p ‐ 3 ) does not, indicating the different aggregation manners of the polymers in the solution and solid states. The monomer and the polymers exhibit redox properties assignable to the ferrocene moieties. Thermal gravimetry analysis (TGA) measurements reveal that a 30% weight reduction occurs at 500 °C yielding black ferromagnetic solids. 相似文献
262.
Ruthenium-based thick-film resistors (TFRs) with lead borosilicate glasses of various compositions have been examined for their electrical properties. A striking increase in resistivity has been observed with lead-depleted glasses, and analysis of this increase reveals that it is derived from the critical loss of Ru ions/clusters in the glass. With high-lead-content glasses, the resistivity decreases by two orders of magnitude, in conjunction with the structural inclination of glass toward PbO·SiO2 , 2PbO·SiO2 , and 4PbO·B2 O3 , which are believed to accommodate more Ru ions/clusters. These behaviors substantiate the role of Ru ions/clusters in glass as an indispensable entity for electrical conduction in TFRs. 相似文献
263.
Futami Junichiro; Seno Masaharu; Ueda Masakazu; Tada Hiroko; Yamada Hidenori 《Protein engineering, design & selection : PEDS》1999,12(11):1013-1019
Pancreatic-type RNases are considered to have cytotoxic potentialdue to their ability to degrade RNA molecules when they enterthe cytosol. However, most of these RNases show little cytotoxicitybecause cells have no active uptake mechanism for these RNasesand because the ubiquitous cytoplasmic RNase inhibitor is consideredto play a protective role against the endocytotic leak of RNasesfrom the outside of cells. To study the cytotoxic potentialof RNase toward malignant cells targeting growth factor receptors,the C-terminus of human RNase 1 was fused to the N-terminusof human basic fibroblast growth factor (bFGF). This RNaseFGFfused protein effectively inhibited the growth of mouse melanomacell line B16/BL6 with high levels of cell surface FGF receptor.This effect appeared to result from prolongation of the overallcell cycle rather than the killing of cells or specific arrestin a particular phase of the cell cycle. Thus, human RNase 1fused to a ligand of cell surface molecules, such as the FGFreceptor, is shown to be an effective candidate for a selectivecell targeting agent with low toxic effects on normal cell types. 相似文献
264.
Takashi Yamaguchi Hiroko Ayaki Lika Asai 《Journal of the American Ceramic Society》1993,76(4):993-997
Interfacial and powder reactions between CaTiO3 and 90PbO–10B2 O3 and 75PbO–25SiO2 binary glasses were studied. The reaction has been analyzed as the effect of B2 O3 and SiO2 additions on the interaction between CaTiO3 and PbO, and discussed from thermodynamic and kinetic points of view. For a fixed CaTiO3 /PbO ratio2 the product perovskite phase became enriched with lead as the amount of additives increased, which is more pronounced with B2 O3 addition. The reaction of CaTiO3 with the lead–boron glass was controlled by a dissolution-precipitation mechanism, and that with the lead-silica glass by a diffusion mechanism. 相似文献
265.
Kato H Izumi Y Hasunuma T Matsuda F Kondo A 《Journal of Bioscience and Bioengineering》2012,113(5):665-673
A method for a widely targeted analysis was developed for the metabolic profiling of yeast central metabolism. The widely targeted method consists of 2 analyses, namely, gas chromatography-quadrupole-mass spectrometry (GC-Q-MS) operated in selected ion monitoring mode with 25m/z channels, and liquid chromatography triple-stage quadrupole (LC-QqQ)-MS operated in multiple reaction monitoring mode. This platform was set up to identify and quantify preselected 99 compounds, including sugars, sugar phosphates, organic acids, amino acids, and cofactors. The method showed good sensitivity and a wide dynamic range. For example, limits of detection for lactate and l-phenylalanine were 1.4fmol and 2.0fmol, respectively. The dynamic ranges for GC-Q-MS analysis and LC-QqQ-MS analysis were approximately 10(2)-10(5) and 10(3)-10(4), respectively. The metabolite profiles of 2 yeast strains, YPH499 and BY4741, under glucose-fermenting conditions were compared using the developed method. Although YPH499 and BY4741 were derived from an identical experimental strain, the profiling analysis successfully revealed a variation in metabolic phenotypes among experimental yeast strains demonstrating that the widely targeted method could be a robust and useful method for the investigation of metabolic phenotypes of Saccharomyces cerevisiae. 相似文献
266.
Simultaneous determination of stevioside, rebaudioside A and glycyrrhizic acid in foods by HPLC 总被引:2,自引:0,他引:2
Sakamaki N Matsumoto H Hagino K Nakazato M Yasuda K 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2004,45(2):81-86
A method for the simultaneous determination of stevioside (Stev), rebaudioside A (RebA) and glycyrrhizic acid (GA) in foods was developed. These sweeteners were extracted from foods, except for dried fishes and shellfishes, by dialysis against Tris-HCl buffer (pH 9.0). Dried fishes and shellfishes were extracted with Tris-HCl buffer--methanol (2:8). The extracts were cleaned up with an Oasis MAX cartridge. The cartridge was washed with 0.05 mol/L sodium acetate (pH 4.0)--methanol (19:1), and the three sweeteners were eluted with 0.1 mol/L phosphoric acid--acetonitrile (1:1). Stev, RebA and GA in the eluate were chromatographed on a Develosil RPAQUEOUS-AR-5 (4.6 mm i.d. x 250 mm) column with 0.02 mol/L phosphoric acid-acetonitrile--methanol (90:55:5) as a mobile phase and monitored at 210 nm for Stev and RebA, and at 254 nm for GA. The recoveries of Stev, RebA and GA from 8 kinds of foods spiked at the level of 0.1 g/kg were 81.7-101%, 81.5-100% and 78.6-95.0%, respectively. The determination limits were 0.01 g/kg in samples. 相似文献
267.
Sakamaki N Nakazato M Matsumoto H Hagino K Yasuda K Nagayama T 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2006,47(2):85-88
A survey of vitamin K contents was carried out on 41 aojiru products and 10 vegetable juice products that were purchased from local markets. Aojiru is a health food made from green vegetables such as kale, ashitaba, mulberry leaf, barley grass and the like. The products are usually provided in various forms, such as frozen, powder and tablet. Vitamin K in samples was extracted with n-hexane, and separated on a C18 column with methanol-ethanol (95 : 5). After separation, vitamin K was converted to the hydroquinone form on a reduction column and determined with a fluorescence detector at lambdaex 240 nm and lambdaem 430 nm. The contents of vitamin K1 (phylloquinone) in frozen samples (n = 8), powder samples (n = 26) and tablet samples (n=7) were 90-190, 410-3,300, and 640-3,100 microg/100 g, respectively, and that in vegetable juice (n= 10) was 1-12 microg/100 g. Vitamin K2 (menaquinone) was not detected. The daily intake of vitamin K from aojiru products was estimated to be 99-380, 20-250 and 27-210 microg/day for frozen, powder and tablet types, respectively. These results suggest that patients prescribed warfarin should take care about their intake of vitamin K from aojiru products. 相似文献
268.
269.
Masao Tokunaga Shinya Kato Akiko Kawamura-Watabe Ryoichi Tanaka Hiroko Tokunaga 《Yeast (Chichester, England)》1998,14(14):1285-1295
Hsp70 is structurally composed of three domains, an amino-terminal ATPase domain, a proximal 18 kDa peptide-binding domain and a distal 10 kDa carboxy-terminal (C-terminal) domain. To dissect the functional significance of the distal 10 kDa domain, and the boundary region between the proximal and distal C-terminal domains of Kar2p in vivo in Saccharomyces cerevisiae, we constructed a series of plasmids which were truncated or had internal deletion mutations in this region. We found that all these mutations are recessive, and that the distal 10 kDa C-terminal domain, including the HDEL ER-retention sequence, is not essential for cell growth, although the major role of this 10 kDa C-terminal domain is due to the function of the HDEL ER-retention signal. We also found that the Kar2p region (Thr492–Thr512), corresponding to the β8-sheet in the peptide-binding domain, which constitutes the bottom plate of the binding pocket in E. coli DnaK, is essential for cell viability, and that the following Kar2p region (Glu513–Lys542), corresponding to α-helices A and B of E. coli DnaK, which was proposed to compose the lid of the binding pocket, is critical but not essential for yeast cell growth. This was further supported by the fact that the latter deletion showed a fully reversible ts phenotype in its growth and only a slight inhibitory effect on the secretion of α-amylase at non-permissive temperature. © 1998 John Wiley & Sons, Ltd. 相似文献
270.
The KlPCK1 gene encoding phosphoenolpyruvate carboxykinase (PEPCK; ATP-dependent) was cloned from the Kluyveromyces lactis genome using a PCR amplicon from Saccharomyces cerevisiae PCK1 gene as a probe. A DNA fragment of about 4·8 kb containing KlPCK1 complemented PEPCK activity of the mutant of S. cerevisiae defective in PEPCK. The KlPCK1 gene has an open reading frame of 1629 bp (543 amino acids). The KlPCK1 nucleotide sequence and deduced amino acid sequence showed 76% and 84% homologies to those of S. cerevisiae PCK1, respectively. Multiple alignment of ATP-dependent PEPCK genes shows highly conserved regions. The nucleotide sequence of KlPCK1 has been submitted to the DDBJ/GenBank/EMBL data bank with Accession Number U88575. © 1998 John Wiley & Sons, Ltd. 相似文献