全文获取类型
收费全文 | 3265篇 |
免费 | 127篇 |
国内免费 | 109篇 |
专业分类
电工技术 | 37篇 |
综合类 | 127篇 |
化学工业 | 2162篇 |
金属工艺 | 36篇 |
机械仪表 | 18篇 |
建筑科学 | 36篇 |
矿业工程 | 3篇 |
能源动力 | 14篇 |
轻工业 | 444篇 |
水利工程 | 5篇 |
石油天然气 | 21篇 |
武器工业 | 4篇 |
无线电 | 49篇 |
一般工业技术 | 312篇 |
冶金工业 | 10篇 |
原子能技术 | 165篇 |
自动化技术 | 58篇 |
出版年
2024年 | 11篇 |
2023年 | 25篇 |
2022年 | 56篇 |
2021年 | 63篇 |
2020年 | 42篇 |
2019年 | 47篇 |
2018年 | 37篇 |
2017年 | 53篇 |
2016年 | 51篇 |
2015年 | 65篇 |
2014年 | 135篇 |
2013年 | 200篇 |
2012年 | 207篇 |
2011年 | 225篇 |
2010年 | 193篇 |
2009年 | 202篇 |
2008年 | 163篇 |
2007年 | 203篇 |
2006年 | 180篇 |
2005年 | 194篇 |
2004年 | 146篇 |
2003年 | 188篇 |
2002年 | 157篇 |
2001年 | 129篇 |
2000年 | 91篇 |
1999年 | 112篇 |
1998年 | 62篇 |
1997年 | 62篇 |
1996年 | 52篇 |
1995年 | 31篇 |
1994年 | 33篇 |
1993年 | 29篇 |
1992年 | 33篇 |
1991年 | 14篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有3501条查询结果,搜索用时 15 毫秒
71.
The aim of this research was to create mathematical models for describing the changes in beer properties by using two chemometric methods applied on the experimental data. The models are intended to be useful and trustworthy for calculating four beer properties based on three easily measured ones. For that purpose, lager and malt beer were packaged in glass bottles, while lager beer was also packaged in polyethylene terephthalate (PET). Samples were placed at room temperature in the dark for 6 months. Fifteen physical and chemical properties of the beer were measured before bottling, immediately after bottling and once per month for the next 6 months. Standard MEBAK and Analytica‐EBC methods of analysis were applied. During the 6 month period, seven properties changed >1%. Two partial least squares regression methods [polynomial regression, partial least squares regression with polynomial regression (PLSR‐PR) and response surface method (PLSR‐RSM)] were used for modelling the relationships amongst multivariate measurements. Models with high statistical significance were determined and two PLSR methods were compared. Both chemometric methods were found to be suitable for modelling physical and chemical changes in the beers during their commercial shelf‐life. The PLS‐RSM method was found to be the more precise and confident method in describing property changes for lager and malt beer in glass bottles, while the polynomial regression model was found to be better for the lager beer packaged in PET. The R2 values determined for polynomial regression model were up to 0.939, while for the random surface method model the values were up to 1.000. Copyright © 2016 The Institute of Brewing & Distilling 相似文献
72.
以在不同剪切速率下自制的5种PET(聚对苯二甲酸乙二醇酯)沉析浆粕为原料,对其进行光学显微镜观察、比表面积测试及筛分分析,并对这5种浆粕的抄造性能进行了研究。结果表明,PET沉析浆粕的组分主要分布在16~30目之间,R16与R30组分比例之和随剪切速率的提高分别为90.7%、90%、84.8%、80.6%和65.6%,主要长度为0.596~1.192 mm,细小纤维(P200)比例随剪切速率的提高分别为1.9%、2.7%、3.4%、10.4%、25%,沉析浆粕的比表面积也随之增大。当PET沉析浆粕∶PET短切纤维=50∶50时,纸张的抗张指数和耐破指数最大,当PET沉析浆粕∶PET短切纤维=30∶70时,纸张的撕裂指数最大。 相似文献
73.
磁控溅射法制备防水透湿织物的性能研究 总被引:10,自引:3,他引:10
介绍子利用磁控溅射法制备透湿织物的基本原理及方法,通过对防水透湿织物憎水性及透湿性的测试分析,发现溅射后织物的憎水性明显提高,且憎水性随溅射功能的增大而减小,随压力的增大而增在,而溅射前后的透湿性受功率和压力的影响不大。 相似文献
74.
为探究不同PTT/PET自卷曲长丝织物在后整理中的表现及其最终成品的弹性性能,选用3个厂家生产的PTT/PET自卷曲长丝试织织物,并在相同工艺条件下进行染整处理,再与氨纶织物进行对比,得到4种织物的质量损失率、纬向染缩率、弹性伸长率、弹性回复率。结果表明:单丝纤度越大,质量损失率越小,染色率越大;织造密度越大,质量损失率越小;弹性伸长率越大,弹性回复率越小。通过光学显微镜、扫描电镜观察及DSC辅助分析发现,PTT/PET复合丝由于单丝比较细,比表面积大,在染整处理过程中受到碱液腐蚀过大而发生2种组分分离的现象,从而失去了双组分丝应有的高弹性。 相似文献
75.
76.
77.
The glass‐transition temperatures and melting behaviors of poly(ethylene terephthalate)/poly(ethylene 2,6‐naphthalate) (PET/PEN) blends were studied. Two blend systems were used for this work, with PET and PEN of different grades. It was found that Tg increases almost linearly with blend composition. Both the Gibbs–DiMarzio equation and the Fox equation fit experimental data very well, indicating copolymer‐like behavior of the blend systems. Multiple melting peaks were observed for all blend samples as well as for PET and PEN. The equilibrium melting point was obtained using the Hoffman–Weeks method. The melting points of PET and PEN were depressed as a result of the formation of miscible blends and copolymers. The Flory–Huggins theory was used to study the melting‐point depression for the blend system, and the Nishi–Wang equation was used to calculate the interaction parameter (χ12). The calculated χ12 is a small negative number, indicating the formation of thermodynamically stable, miscible blends. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 11–22, 2001 相似文献
78.
79.
80.
啤酒包装塑料化的研究开发近况 总被引:1,自引:0,他引:1
近年来,全球每年的啤酒生产产生了巨大的啤酒包装市场,其中玻璃瓶包装占了大约70%。因玻璃瓶存在运输、装卸费用高,洗瓶、灌装、运输等环节破损率高、损失大,还存在安全隐患等缺点,导致近年来国内外啤酒包装行业开始大力研究和开发PEN材料、生产高阻隔性的多层瓶和PET材料上的涂覆等技术,并取得较快的发展。啤酒包装容器的塑料化可减少运输、洗瓶、上瓶等环节的成本和提高生产效率,将逐渐成为国际、国内啤酒包装的新宠,PET瓶将逐渐替代玻璃瓶啤酒包装。(孙悟) 相似文献