全文获取类型
收费全文 | 1521111篇 |
免费 | 25904篇 |
国内免费 | 6966篇 |
专业分类
电工技术 | 34337篇 |
综合类 | 6386篇 |
化学工业 | 270975篇 |
金属工艺 | 64499篇 |
机械仪表 | 42518篇 |
建筑科学 | 46101篇 |
矿业工程 | 11454篇 |
能源动力 | 50308篇 |
轻工业 | 112673篇 |
水利工程 | 15365篇 |
石油天然气 | 37634篇 |
武器工业 | 135篇 |
无线电 | 196774篇 |
一般工业技术 | 284826篇 |
冶金工业 | 176942篇 |
原子能技术 | 33947篇 |
自动化技术 | 169107篇 |
出版年
2021年 | 15544篇 |
2020年 | 11811篇 |
2019年 | 14602篇 |
2018年 | 15569篇 |
2017年 | 15022篇 |
2016年 | 21253篇 |
2015年 | 17326篇 |
2014年 | 28629篇 |
2013年 | 87886篇 |
2012年 | 35452篇 |
2011年 | 47896篇 |
2010年 | 42602篇 |
2009年 | 50964篇 |
2008年 | 44686篇 |
2007年 | 41979篇 |
2006年 | 44567篇 |
2005年 | 39381篇 |
2004年 | 41629篇 |
2003年 | 41391篇 |
2002年 | 40431篇 |
2001年 | 37676篇 |
2000年 | 36035篇 |
1999年 | 35495篇 |
1998年 | 49806篇 |
1997年 | 41911篇 |
1996年 | 37089篇 |
1995年 | 31674篇 |
1994年 | 29603篇 |
1993年 | 29516篇 |
1992年 | 26316篇 |
1991年 | 23402篇 |
1990年 | 23776篇 |
1989年 | 22794篇 |
1988年 | 21335篇 |
1987年 | 19599篇 |
1986年 | 18965篇 |
1985年 | 22304篇 |
1984年 | 22400篇 |
1983年 | 20337篇 |
1982年 | 19316篇 |
1981年 | 19472篇 |
1980年 | 18022篇 |
1979年 | 18572篇 |
1978年 | 17816篇 |
1977年 | 17737篇 |
1976年 | 19047篇 |
1975年 | 16075篇 |
1974年 | 15554篇 |
1973年 | 15615篇 |
1972年 | 13098篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
251.
252.
253.
Physical Stability of Octenyl Succinate–Modified Polysaccharides and Whey Proteins for Potential Use as Bioactive Carriers in Food Systems 下载免费PDF全文
The high cost and potential toxicity of biodegradable polymers like poly(lactic‐co‐glycolic)acid (PLGA) has increased the interest in natural and modified biopolymers as bioactive carriers. This study characterized the physical stability (water sorption and state transition behavior) of selected starch and proteins: octenyl succinate–modified depolymerized waxy corn starch (DWxCn), waxy rice starch (DWxRc), phytoglycogen, whey protein concentrate (80%, WPC), whey protein isolate (WPI), and α‐lactalbumin (α‐L) to determine their potential as carriers of bioactive compounds under different environmental conditions. After enzyme modification and particle size characterization, glass transition temperature and moisture isotherms were used to characterize the systems. DWxCn and DWxRc had increased water sorption compared to native starch. The level of octenyl succinate anhydrate (OSA) modification (3% and 7%) did not reduce the water sorption of the DWxCn and phytoglycogen samples. The Guggenheim–Andersen–de Boer model indicated that native waxy corn had significantly (P < 0.05) higher water monolayer capacity followed by 3%‐OSA‐modified DWxCn, WPI, 3%‐OSA‐modified DWxRc, α‐L, and native phytoglycogen. WPC had significantly lower water monolayer capacity. All Tg values matched with the solid‐like appearance of the biopolymers. Native polysaccharides and whey proteins had higher glass transition temperature (Tg) values. On the other hand, depolymerized waxy starches at 7%‐OSA modification had a “melted” appearance when exposed to environments with high relative humidity (above 70%) after 10 days at 23 °C. The use of depolymerized and OSA‐modified polysaccharides blended with proteins created more stable blends of biopolymers. Hence, this biopolymer would be suitable for materials exposed to high humidity environments in food applications. 相似文献
254.
255.
256.
257.
H. Cherfouh O. Fellahi T. Hadjersi B. Marsan 《International Journal of Hydrogen Energy》2018,43(6):3431-3440
This work aims at developing a new composite material based on nanosized semiconducting CuInS2 (CIS) particles combined with silicon nanowires grown on a silicon substrate (SiNWs/Si) for photoelectrochemical (PEC)-splitting of water. The CIS particles were prepared via a colloidal method using N-methylimidazole (NMI) as the solvent and an annealing treatment. The SiNWs were obtained by chemical etching of silicon (100) substrates assisted by a metal. The CIS/SiNWs/Si composite material was obtained by deposition of an aliquot of a suspension of CIS particles onto the SiNWs/Si substrate, using spin coating followed by a drying step. The XRD pattern demonstrated that CuInS2 grows in the tetragonal/chalcopyrite phase, while SiNWs/Si presents a cubic structure. The SEM images show semi-spherical particles (~10 nm) distributed on the surface of silicon nanowires (~10 μm). The EIS measurements reveal n-type conductivity for CIS, SiNWs/Si and CIS/SiNWs/Si materials, which could favour the oxidation reaction of water molecules. 相似文献
258.
259.
Wireless Personal Communications - This paper considers half-duplex cooperative spectrum sharing scheme where both primary and secondary systems mutually cooperate with each other to exploit... 相似文献
260.