全文获取类型
收费全文 | 31006篇 |
免费 | 2635篇 |
国内免费 | 845篇 |
专业分类
电工技术 | 2035篇 |
综合类 | 2061篇 |
化学工业 | 3960篇 |
金属工艺 | 970篇 |
机械仪表 | 1298篇 |
建筑科学 | 2430篇 |
矿业工程 | 1351篇 |
能源动力 | 1372篇 |
轻工业 | 10621篇 |
水利工程 | 780篇 |
石油天然气 | 1812篇 |
武器工业 | 99篇 |
无线电 | 939篇 |
一般工业技术 | 1227篇 |
冶金工业 | 1315篇 |
原子能技术 | 496篇 |
自动化技术 | 1720篇 |
出版年
2024年 | 153篇 |
2023年 | 380篇 |
2022年 | 945篇 |
2021年 | 1007篇 |
2020年 | 1072篇 |
2019年 | 963篇 |
2018年 | 852篇 |
2017年 | 965篇 |
2016年 | 1012篇 |
2015年 | 1117篇 |
2014年 | 1808篇 |
2013年 | 1972篇 |
2012年 | 2395篇 |
2011年 | 2274篇 |
2010年 | 1501篇 |
2009年 | 1511篇 |
2008年 | 1341篇 |
2007年 | 1819篇 |
2006年 | 1775篇 |
2005年 | 1447篇 |
2004年 | 1302篇 |
2003年 | 1136篇 |
2002年 | 1059篇 |
2001年 | 880篇 |
2000年 | 683篇 |
1999年 | 605篇 |
1998年 | 432篇 |
1997年 | 386篇 |
1996年 | 320篇 |
1995年 | 273篇 |
1994年 | 227篇 |
1993年 | 179篇 |
1992年 | 155篇 |
1991年 | 115篇 |
1990年 | 78篇 |
1989年 | 77篇 |
1988年 | 51篇 |
1987年 | 42篇 |
1986年 | 24篇 |
1985年 | 10篇 |
1984年 | 17篇 |
1983年 | 7篇 |
1982年 | 12篇 |
1981年 | 14篇 |
1980年 | 19篇 |
1979年 | 14篇 |
1977年 | 8篇 |
1976年 | 11篇 |
1975年 | 15篇 |
1973年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Hassan Hajjaj Gerard Goma Jean M. François 《International Journal of Food Science & Technology》2015,50(8):1731-1736
In submerged cultures performed in chemically defined fermentation medium containing glucose and glutamate, the growth and production of water‐soluble red pigments and citrinin by the filamentous fungus Monascus ruber were studied under various carbon/nitrogen (C/N) ratios. The specific production of the red pigments was optimal at a glucose/glutamate ratio of about 10 and then steadily decreased at higher C/N ratio. In contrast, the production of the mycotoxin increased with increased C/N with an optimum in the range of 30–45. In a fed‐batch mode, it was also found that the production of pigments was not favoured in fed‐batch mode by feeding the medium with glucose while keeping the C/N ratio lower than 10. This low production likely resulted from concurrent high accumulation of L‐malic acid that was reported to inhibit this production. In contrast, this mode of cultivation was rather favourable for the production of the mycotoxin. 相似文献
4.
Bioactive compounds and antioxidant activities of the Korean lotus leaf (Nelumbo nucifera) condiment: volatile and nonvolatile metabolite profiling during fermentation 下载免费PDF全文
Recent studies have shown that lotus (Nelumbo nucifera) leaf has various pharmacological effects. However, there have been no scientific investigations into these leaves as a fermented crude liquid. This study compared the in vitro antioxidant capacity of lotus leaf‐fermented broth (LLFB) with that of 57° Brix sugar broth (SB) as a control over a period of 6 months based on 1,1‐diphenyl‐2‐picrylhydrazyl radical scavenging activity, ferric ion reducing power, superoxide dismutase‐like activity, tyrosinase inhibition and nitrite scavenging activity. The dominant species during fermentation process were Leuconostoc lactis and Saccharomyces cerevisiae for LLFB. A total of thirty‐six metabolites such as alkaloids, fatty acids, organic acids, phenolics, sugar and sugar derivatives, ethyl esters and monoterpenoids differed between SB and LLFB using gas chromatography–mass spectrometry. Meanwhile, nine volatile compounds in LLFB contributed pleasant, slightly sweetish and fruity odour of condiment and sensory evaluation score of 4.06 ± 1.52 in the proportion of 1:9 LLFB/water. 相似文献
5.
Francielo Vendruscolo 《国际能源研究杂志》2015,39(3):293-302
Hydrogen is a clean energy carrier with great potential to be an alternative fuel. Anaerobic hydrogen fermentation seems to be more favorable, since hydrogen is yielded at high rates and various organic waste and wastewater enriched with carbohydrates as substrate result in low cost for hydrogen production. Abundant biomass from various industries could be a source for biohydrogen production where combination of waste treatment and energy production would be an advantage. Carbohydrate‐rich nitrogen‐deficient solid wastes such as starch residues can be used for hydrogen production by using suitable bioprocess technologies. Alternatively, converting biomass into gaseous fuels, such as biohydrogen, is possibly the most efficient way to use these agroindustrial residues. This review summarizes the potential of starch agroindustrial residues as a substrate for biohydrogen production. Types of potential starch agroindustrial residues, recent developments and bio‐processing conditions for biohydrogen production will be discussed. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
6.
This paper deals with the investigation of the effect of hygrothermal conditions on the bending of nanoplates using Levy type solution model employing the state-space concept. The nanoplates are assumed to be subjected to a hygrothermal environment. The two-unknown function plate theory is used to derive the governing differential equations on the basis of Eringen's nonlocal elasticity theory. The governing equations contain the small scale effect as well as hygrothermal and mechanical effects. These equations are converted into a set of first-order linear ordinary differential equations with constant coefficients. Analytical solution of bending response for nanoplates under combinations of simply supported, clamped and free boundary conditions is obtained. Comparison of the results with those being in the open literature is made. The influences played by small scale parameter, temperature rise, the degree of moisture concentration, boundary conditions, plate aspect ratio and side-to-thickness ratio are studied. 相似文献
7.
通过对接轨站设置位置和布置图型主要影响因素的分析。按照能够充分反映接轨站作业特点的交接方式。对接轨站所采用的布置图型进行了归纳和分类。 相似文献
8.
9.
The three-dimensional morphology of polyethylene single crystals grown from dilute solution has been examined by atomic force microscopy. Single crystals were deposited on a soft ground of aqueous solution of poly(vinyl alcohol) (PVA) to avoid the collapse of thin lamellar crystals with thickness of 10 nm. The observation of single crystals on dried PVA clarifies the morphology of a chair type crystal as well as well-known hollow pyramidal type. It has been confirmed that the screw dislocations in the chair type follow a selection rule of the handedness in a manner to relieve the distortion in the chair type. 相似文献
10.
江苏复杂小断块油藏老井侧钻实践与认识 总被引:2,自引:0,他引:2
利用停关、低效井实施老井侧钻,其条件包括油藏、井身及技术经济等3个方面。侧钻效益的好坏与油藏类型、侧钻目标有着很大关系,侧钻断块油层、挖掘构造高部位剩余油成功率高,边底水、高渗透油藏侧钻效果好。实践表明,老井侧钻是提高江苏复杂小断块油藏开发效果,降低投资、提高效益的一项重要手段。 相似文献