全文获取类型
收费全文 | 1237篇 |
免费 | 21篇 |
国内免费 | 4篇 |
学科分类
工业技术 | 1262篇 |
出版年
2022年 | 11篇 |
2021年 | 21篇 |
2020年 | 7篇 |
2019年 | 9篇 |
2018年 | 7篇 |
2017年 | 13篇 |
2016年 | 23篇 |
2015年 | 13篇 |
2014年 | 31篇 |
2013年 | 62篇 |
2012年 | 47篇 |
2011年 | 82篇 |
2010年 | 46篇 |
2009年 | 49篇 |
2008年 | 71篇 |
2007年 | 69篇 |
2006年 | 57篇 |
2005年 | 47篇 |
2004年 | 43篇 |
2003年 | 52篇 |
2002年 | 45篇 |
2001年 | 33篇 |
2000年 | 23篇 |
1999年 | 28篇 |
1998年 | 38篇 |
1997年 | 30篇 |
1996年 | 21篇 |
1995年 | 21篇 |
1994年 | 16篇 |
1993年 | 21篇 |
1992年 | 15篇 |
1991年 | 20篇 |
1990年 | 14篇 |
1989年 | 13篇 |
1988年 | 19篇 |
1987年 | 11篇 |
1986年 | 14篇 |
1985年 | 16篇 |
1984年 | 18篇 |
1983年 | 8篇 |
1982年 | 8篇 |
1981年 | 8篇 |
1980年 | 9篇 |
1979年 | 16篇 |
1978年 | 11篇 |
1976年 | 6篇 |
1974年 | 4篇 |
1973年 | 4篇 |
1970年 | 2篇 |
1968年 | 3篇 |
排序方式: 共有1262条查询结果,搜索用时 78 毫秒
991.
The physical aging of a poly(methyl methacrylate) (PMMA) copolymer having a small amount of ethyl methacrylate was investigated below its glass transition temperature (Tg) using dynamic viscoelastic measurements. The results were compared with those from homo-PMMAs to investigate how the comonomer in the copolymer affects the physical aging of the glass. Annealing temperatures were classified into two categories by the glass transition temperature of a poly(ethyl methacrylate) (TgPEMA; ca. 65°C). The relaxation rate of the copolymer was faster than those of the homo-PMMAs when the samples were aged below TgPEMA, but the rates were equal when aged at above TgPEMA. The experimental results are discussed in terms of the segmental motion. 相似文献
992.
Ogawa A Nosaka N Kasai M Aoyama T Okazaki M Igarashi O Kondo K 《Journal of oleo science》2007,56(6):283-287
This study investigated the effects of a liquid meal containing medium- and long-chain triacylglycerols (MLCT) on diet-induced thermogenesis (DIT) and was conducted in double-blind cross-over manner. Twenty subjects participated in this examination. The subjects consumed the liquid meal, which was made with 14 g of canola oil (LCT, long-chain triacylglycerols) or MLCT containing about 12% medium-chain fatty acids (MCFA). Oxygen consumption and carbon dioxide production were measured by indirect calorimetry. Resting energy expenditure (REE) was determined based on there parameters, applying the equation of Weir. Increase in DIT after ingesting the liquid meal with MLCT during 6h was significantly greater than with LCT (P<0.05). The results suggest that the substitution of MLCT for cooking oil is useful to control body weigh and fat in subjects. 相似文献
993.
994.
Shimaoka M Takenaka Y Kurahashi O Kawasaki H Matsui H 《Journal of Bioscience and Bioengineering》2007,103(3):255-261
The effect of a phosphoribosylpyrophosphate (PRPP) synthetase gene (prs) that was desensitized to feedback inhibition by ADP on inosine accumulation was investigated using an inosine-producing mutant of Escherichia coli. At the same time, various types of plasmid having a PRPP amidotransferase gene (purF) that was desensitized to feedback inhibition by AMP and GMP were also investigated to improve inosine productivity using a compatible plasmid containing prs with a plasmid containing purF. The recombinant E. coli I-9 harboring a low-copy-number plasmid having the desensitized-purF (pMWKQ) accumulated 3.6 g/l inosine from 40 g/l glucose in a 2-d culture. Furthermore, desensitized-prs amplification, in addition to purF, resulted in the accumulation of 6.2 g/l inosine. Additionally, through these experiments, a spontaneous mutant with an enhanced inosine-producing ability compared with the parent strain I-9 was obtained. The spontaneous mutant I-9m harboring only pMWKQ and I-9m harboring both pMWKQ and pSTVDA (a plasmid having the desensitized-prs) accumulated 6.7 g/l and 7.5 g/l inosine, respectively, from 40 g/l glucose in a 3-d culture. 相似文献
995.
Ino K Ito A Wu Y Saito N Hibino E Takai O Honda H 《Journal of Bioscience and Bioengineering》2007,104(5):420-423
In this study, we applied an ultra-water-repellent film to cell culture. We cultured cells in droplets on the film and fabricated cell aggregates. Furthermore, we allocated cells on micropatterned surfaces consisting of ultra-water-repellent regions and cell culture-treated regions. The results show that the material is useful for cell culture. 相似文献
996.
The coexistence of protein disulfide isomerase (PDI) in the oxidative refolding of a fully reduced hen egg white lysozyme brought about a final recovered activity significantly exceeding 100% in addition to the expected acceleration effect. This increase could not be explained by the simple increase produced by suppressing aggregation. After examination of the starting material and assay system, it was concluded that PDI enhances the activity of renatured lysozyme. 相似文献
997.
Supercritical water impregnation is a novel method, which utilizes high diffusivity of the fluid with hydrothermal synthesis
allowing nano-particles to deposit on porous materials in well-dispersed condition. In this work, silver nano-particles were
deposited on the surface of α-alumina supports using metal acetate solution. TEM-EDS analyses clearly identified the silver
particle of two kinds, those deposited on α-alumina surface and those gathering in bulk phase. Their particle size distribution
showed differences in propensity, implying that particle formation were via different mechanism. The difference in particle
deposition mechanism was also confirmed from the results of other operational factors investigated. Furthermore, the mechanism
of particle deposition to alumina support surface have been proposed based on the experimental results and reported observation
of nucleation and particle growth steps during the hydrothermal synthesis. In addition, the mechanism of silver particle formation
has been discussed in detail. 相似文献
998.
Endo T Hisamichi Y Kimura O Haraguchi K Baker CS 《The Science of the total environment》2008,401(1-3):73-80
Total mercury (T-Hg), methyl mercury (M-Hg), cadmium (Cd), selenium (Se), zinc (Zn) and copper (Cu) concentrations in the organs of melon-headed whales from a mass stranding on the Japanese coast were analyzed. The mean concentration of T-Hg in the liver (126+/-97 microg/wet g, n=13) was markedly higher than those in kidney (6.34+/-2.36 microg/wet g, n=12) and muscle (4.90+/-2.33 microg/wet g, n=15). In contrast, the mean concentration of M-Hg in the liver (9.08+/-2.24 microg/wet g) was similar to those in the kidney (3.47+/-0.91 microg/wet g) and muscle (3.78+/-1.53 microg/wet g). The mean percentage of M-Hg in the T-Hg found in the liver (13.1+/-10.3) was significantly lower than those in the kidney (58.3+/-15.0) and muscle (78.9+/-8.4). The molar ratio of T-Hg to Se in the liver was effectively 1.0, but those in the kidney and muscle were markedly lower. Conversely, the mean concentration of Cd was markedly higher in the kidney (24.4+/-7.4 microg/wet g) than in the liver (7.24+/-2.08 microg/wet g) and muscle (less than 0.05 microg/wet g). These results suggest that the formation of Hg-Se compounds mainly occurs in the liver after the demethylation of M-Hg, and Cd preferentially accumulates in the kidney of melon-headed whales. 相似文献
999.
Keita Yunoki Osamu Kukino Yoshitaka Nadachi Takehiko Fujino Masao Ohnishi 《Journal of the American Oil Chemists' Society》2008,85(5):427-433
Complex lipids including sphingolipid and plasmalogens were expected to be used as functional supplement, although their physiological
activities have not been fully demonstrated. Although these complex lipids exist voluminously in brain and nervous tissues,
hardly any animal resources of these lipids have been used since the outbreak of bovine spongiform encephalopathy. Thus, the
chemical composition and concentration method of complex lipids from the skin of mature laying hens, a huge amount of which
is wasted every year, has been investigated. Total lipid yield (32 g/100 g) prepared from chicken skin contained 2% complex
lipids. Total lipids predominantly consisted of triacylglycerol (TAG), with phosphatidylcholine, sphingomyelin (SM) and phosphatidylethanolamine
(PE) generally predominant as complex lipids. PE was primarily plasmalogens (62 mol%), of which arachidonic acid (47.6 mol%)
and docosahexaenoic acid (11.2 mol%) were the predominant fatty acids. The component sphingoid base of sphingomyelin was almost
totally 4-trans sphingenine (sphingosine). The complex lipids were able to be separated from an ethanol extract of minced skin in good yield
by solvent fractionation with a hexane/ethanol system. Moreover, highly purified SM (>95 wt%) was prepared by a combination
of solvent fractionation and alkaline/acidic hydrolysis from the ethanol extract. Thus, it was shown that culled chicken skin
could be a potential resource of the antioxidant phospholipid plasmalogens and human-type sphingolipid. 相似文献
1000.
Injection molded optical plastic parts require accurate replication of micro‐scale features. The effects of melt viscosity and molding conditions on replication of microscopic v‐groove features in injection molded parts were examined for PC with different molecular weight. The micro‐scale feature size was a continuous v‐groove with 20 μm in depth and 50 μm in width. For injection molding conditions, melt temperature, mold temperature, injection velocity and holding pressure were varied in three levels. As the result, the mold temperature had significantly affected replication for all polymers with different molecular weight. Additionally, the molding conditions that lower melt viscosity led to improved replication. In the case of polymer with high molecular weight, the viscosity decreased with increasing melt temperature. It has been found that high replication of micro‐scale features could be achieved by higher mold temperature and higher melt temperature even with high viscosity PC. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers 相似文献