全文获取类型
收费全文 | 24638篇 |
免费 | 2064篇 |
国内免费 | 1154篇 |
专业分类
电工技术 | 1462篇 |
综合类 | 1597篇 |
化学工业 | 4218篇 |
金属工艺 | 1758篇 |
机械仪表 | 1506篇 |
建筑科学 | 1884篇 |
矿业工程 | 868篇 |
能源动力 | 609篇 |
轻工业 | 1688篇 |
水利工程 | 508篇 |
石油天然气 | 1813篇 |
武器工业 | 243篇 |
无线电 | 2441篇 |
一般工业技术 | 3085篇 |
冶金工业 | 1270篇 |
原子能技术 | 248篇 |
自动化技术 | 2658篇 |
出版年
2024年 | 90篇 |
2023年 | 384篇 |
2022年 | 687篇 |
2021年 | 1059篇 |
2020年 | 793篇 |
2019年 | 653篇 |
2018年 | 702篇 |
2017年 | 823篇 |
2016年 | 703篇 |
2015年 | 1026篇 |
2014年 | 1283篇 |
2013年 | 1426篇 |
2012年 | 1541篇 |
2011年 | 1741篇 |
2010年 | 1477篇 |
2009年 | 1431篇 |
2008年 | 1299篇 |
2007年 | 1425篇 |
2006年 | 1397篇 |
2005年 | 1183篇 |
2004年 | 780篇 |
2003年 | 690篇 |
2002年 | 690篇 |
2001年 | 571篇 |
2000年 | 580篇 |
1999年 | 664篇 |
1998年 | 468篇 |
1997年 | 440篇 |
1996年 | 398篇 |
1995年 | 344篇 |
1994年 | 311篇 |
1993年 | 208篇 |
1992年 | 159篇 |
1991年 | 109篇 |
1990年 | 80篇 |
1989年 | 60篇 |
1988年 | 62篇 |
1987年 | 37篇 |
1986年 | 25篇 |
1985年 | 10篇 |
1984年 | 11篇 |
1983年 | 13篇 |
1982年 | 11篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1959年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 209 毫秒
11.
Yuxi Guo Xuefeng Chen Pin Gong Fuxin Chen Dandan Cui Mengrao Wang 《International Journal of Food Science & Technology》2021,56(10):4970-4982
In vitro digestion models are widely used to study the structural changes, digestion and release of food components under simulated gastrointestinal conditions. As compared to the in vivo digestion tests, the in vitro digestion reflects the digestion and utilisation of food after ingestion and has the advantages of being time consuming, inexpensive, reproducible and free from moral and ethical restrictions. This study reviewed the current research studies on the in vitro simulated digestion of polysaccharides conducted in the last 5 years and focused on the oral, gastric and intestinal digestion models, with the aim of providing a basis for the further testing of changes in the content, structure and active ingredients of polysaccharides before and after digestion. 相似文献
12.
Journal of Computer Science and Technology - DOACROSS loops are significant parts in many important scientific and engineering applications, which are generally exploited pipeline/wave-front... 相似文献
13.
目前瞬变电磁法勘探广泛运用在煤矿系统,主要解决地下水的问题.随着科技的发展和进步,瞬变电磁法勘探仪器大致分2类,国外仪器一般采用大功率、大线框的大定源框内回装置;国内仪器一般采用小功率小线圈、低电压、高电流的重叠回线装置.在作业过程中,瞬变电磁法发射线框与接收设备受电磁干扰较为严重,不同的工作装置优势不同,抗干扰能力不同.通过对山西潞安集团李村矿的工作研究,证明了采用不同工作装置在高压线附近进行勘探,可起到互补的作用,达到勘探的目的 . 相似文献
14.
Shensong Wang Zheng Wu Jie Chen Jiangping Ma Jingshi Ying Shouchen Cui Shigang Yu Yongming Hu Jinhe Zhao Yanmin Jia 《Ceramics International》2019,45(9):11703-11708
In this work, the hydrothermally-synthesized sodium niobate nanowires were used to decompose Rhodamine B dye solution through the piezo-catalytic effect. With the sodium niobate catalyst, a high piezo-catalytic degradation ratio of ~80% was achieved under the excitation of vibration for the Rhodamine B dye solution (~5?mg/l). These active species in the catalytic process, hydroxyl radicals and superoxide radicals with the strong oxidation ability, were also observed, which confirmed the key role of piezoelectric effect for piezo-catalysis. The piezo-catalysis of sodium niobate nanowires provides a high-efficiency and reusable tool in application in depredating the dye wastewater. 相似文献
15.
Synergistic flame retardant effects of activated carbon and molybdenum oxide in poly(vinyl chloride) 下载免费PDF全文
Mengjiao Zhang Weihong Wu Shaorui He Xue Wang Yunhong Jiao Hongqiang Qu Jianzhong Xu 《Polymer International》2018,67(4):445-452
The synergistic effects of activated carbon (AC) and molybdenum oxide (MoO3) in improving the flame retardancy of poly(vinyl chloride) (PVC) were investigated. The effects of AC, MoO3 and their mixture with a mass ratio of 1:1 on the flame retardancy and smoke suppression properties of PVC were studied using the limiting oxygen index and cone calorimeter tests. It was found that the flame retardancy of the relatively cheaper AC was slightly weaker than that of MoO3. In addition, the incorporation of AC and MoO3 greatly reduced the total heat release and improved smoke suppressant property of PVC composites. When the total content of AC and MoO3 was 10 phr, PVC/AC/MoO3 had the lowest peak heat release rate and peak smoke production rate values of 173.80 kW m?2 and 0.1472 m2 s?1, which represented reductions of 47.3 and 59.9%, respectively, compared with those of PVC. Furthermore, thermogravimetric analysis and gel content tests were used to analyze the flame retardant mechanism of AC and MoO3, with results showing that AC could promote early crosslinking in PVC. Char residue left after heating at 500 °C was analyzed using scanning electron microscopy and Raman spectroscopy, and the results showed that MoO3 produced the most compact char, with the smallest and most organized carbonaceous microstructures. © 2017 Society of Chemical Industry 相似文献
16.
17.
18.
针对郭庄煤业选煤厂振动筛振动筛分方式可靠性差、筛分效率低下、物料筛分率低的难题,本文提出了三种新的振动筛分方案,对不同筛分方案的实际应用效果进行了分析。结果表明三移动一摆动的振动筛分方式对物料的综合分散度最高,稳定性好,该筛分方案已在郭庄煤业选煤厂煤炭筛分过程中得到了全面的应用。 相似文献
20.
Yong Liu Kangzhuang Chen Fengbo Dong Shuai Peng Yongjie Cui Chenyu Zhang Keqing Han Muhuo Yu Hui Zhang 《Ceramics International》2018,44(9):10199-10203
In this paper, polyborosilazane precursor was synthesied from HMDZ, HSiCl3, BCl3 and CH3NH2 using a multistep method. By controlling the storage conditions, parts of the polyborosilazane fibers were hydrolyzed. FT-IR, NMR, XRD, TEM and monofilament tensile strength test were employed to study the effects of hydrolysis of precursor on the structures and properties of polymer-derived SiBN ceramic fibers. FT-IR and NMR results indicate that Si-N group in PBSZ reacts with H2O to form Si-O-Si group. After pyrolysis reaction at 1400℃, Si-O-Si group will finally transformed into highly ordered cristobalite and β-quartz, resulting in formation of the wrinkled surface of the obtained SiBN ceramic fiber. The strip-like defects on fiber surface, according to monofilament tensile strength test, had a significant effect on mechanical property of the obtained SiBN ceramic fiber and caused no increase in fiber tensile strength of hydrolytic polyborosilazane fiber before and after pyrolytic process. 相似文献