全文获取类型
收费全文 | 285274篇 |
免费 | 37659篇 |
国内免费 | 14284篇 |
专业分类
电工技术 | 20211篇 |
技术理论 | 6篇 |
综合类 | 19710篇 |
化学工业 | 51392篇 |
金属工艺 | 15298篇 |
机械仪表 | 17145篇 |
建筑科学 | 22226篇 |
矿业工程 | 7259篇 |
能源动力 | 8357篇 |
轻工业 | 25742篇 |
水利工程 | 6216篇 |
石油天然气 | 11809篇 |
武器工业 | 2651篇 |
无线电 | 37568篇 |
一般工业技术 | 37011篇 |
冶金工业 | 11282篇 |
原子能技术 | 2899篇 |
自动化技术 | 40435篇 |
出版年
2024年 | 890篇 |
2023年 | 3760篇 |
2022年 | 7368篇 |
2021年 | 10896篇 |
2020年 | 9047篇 |
2019年 | 8900篇 |
2018年 | 9576篇 |
2017年 | 11137篇 |
2016年 | 10534篇 |
2015年 | 14138篇 |
2014年 | 17073篇 |
2013年 | 20923篇 |
2012年 | 21278篇 |
2011年 | 22205篇 |
2010年 | 20689篇 |
2009年 | 19637篇 |
2008年 | 18983篇 |
2007年 | 18059篇 |
2006年 | 16602篇 |
2005年 | 13246篇 |
2004年 | 9500篇 |
2003年 | 8144篇 |
2002年 | 7946篇 |
2001年 | 6930篇 |
2000年 | 5994篇 |
1999年 | 4791篇 |
1998年 | 3385篇 |
1997年 | 2863篇 |
1996年 | 2593篇 |
1995年 | 2183篇 |
1994年 | 1750篇 |
1993年 | 1275篇 |
1992年 | 1012篇 |
1991年 | 765篇 |
1990年 | 622篇 |
1989年 | 501篇 |
1988年 | 392篇 |
1987年 | 277篇 |
1986年 | 238篇 |
1985年 | 171篇 |
1984年 | 130篇 |
1983年 | 92篇 |
1982年 | 96篇 |
1981年 | 101篇 |
1980年 | 92篇 |
1979年 | 59篇 |
1978年 | 42篇 |
1977年 | 43篇 |
1976年 | 64篇 |
1973年 | 27篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
72.
Scientometrics - University–industry R&;amp;D collaboration is a key driver of participating firms’ technological capability. However, there is still debate on the determinants of a... 相似文献
73.
74.
随着信息时代的迅速发展,云计算数据访问安全已经成为了用户最关心的问题。身份认证技术是确保参与者在开放的网络环境中实现安全通信的一种重要手段,如何利用身份认证技术为云环境安全保驾护航,成为学者研究的热点。文中通过公钥基础设施(Public Key Infrastructure,PKI)颁发CA证书以在不同云服务间建立信任,将多个采用身份密码体制(Identity-Based Encryption,IBE)的云联合起来;采用分层身份加密体系,引入共享密钥技术,通过选取成环结构,提出一种PKI-IBE混合认证模型方案,并对方案的安全性进行分析,从理论上证明了云环境下PKI-IBE(Public Key Infrastructure-Identity-Based Encryption)同层成环模型提供服务的可行性。同时文中设计了一种基于该模型的签密技术,通过公私密钥对实现云内认证以及跨云认证。安全性理论证明与性能分析表明,该方案在计算量稍增加的前提下,保证了足够的安全性,更加满足云环境下的用户分属不同云域的认证以及用户安全访问的需求,有效解决了云环境中数据访问的安全问题。 相似文献
75.
文章主要研究用水浸法提取落葵浆果天然染料及研究浸提液对羊毛织物的染色性能。以水为提取剂提取落葵浆果天然染料,探讨提取工艺中料液比、提取温度及时间等因素对落葵浆果天然染料提取效果的影响。研究结果表明,落葵浆果水浸提法优化工艺为:料液比1∶20、提取温度70℃、提取时间30 min。落葵浆果天然染料可以对羊毛织物进行染色,媒染染色与直接染色相比,染色深度深且会呈现不同的颜色。由于媒染剂的络合作用,媒染染色色牢度比直接染色普遍高1~2级。 相似文献
76.
Molecular structure and granule morphology of native and heat‐moisture‐treated pinhão starch
下载免费PDF全文
![点击此处可从《International Journal of Food Science & Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Vania Z. Pinto Khalid Moomand Nathan L. Vanier Rosana Colussi Franciene A. Villanova Elessandra R. Zavareze Loong‐Tak Lim Alvaro R. G. Dias 《International Journal of Food Science & Technology》2015,50(2):282-289
Pinhão seed is an unconventional source of starch and the pines grow up in native forests of southern Latin America. In this study, pinhão starch was adjusted at 15, 20 and 25% moisture content and heated to 100, 110 and 120 °C for 1 h. A decrease in λ max (starch/iodine complex) was observed as a result of increase in temperature and moisture content of HMT. The ratio of crystalline to amorphous phase in pinhão starch was determined via Fourier transform infra red by taking 1045/1022 band ratio. A decrease in crystallinity occurred as a result of HMT. Polarised light microscopy indicated a loss of birefringence of starch granules under 120 °C at 25% moisture content. Granule size distribution was further confirmed via scanning electron microscopy which showed the HMT effects. These results increased the understanding on molecular and structural properties of HMT pinhão starch and broadened its food and nonfood industrial applications. 相似文献
77.
Effect of gums on viability and β‐galactosidase activity of Lactobacillus spp. in milk drink during refrigerated storage
下载免费PDF全文
![点击此处可从《International Journal of Food Science & Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Bernice D. Karlton‐Senaye Reza Tahergorabi Valerie L. Giddings Salam A. Ibrahim 《International Journal of Food Science & Technology》2015,50(1):32-40
The viability and β‐galactosidase activity of four Lactobacillus strains in milk drink containing gums during 28 days of refrigerated storage at 4 °C were assessed. The population of Lactobacillus rhamnosus GGB101 and Lactobacillus rhamnosus GGB103 were maintained, whereas the population of Lactobacillus reuteri DSM20016 and Lactobacillus reuteri SD2112 significantly decreased. The recommended level of 6 log CFU g?1 was exceeded for all tested trains throughout storage. The highest viable number of Lactobacillus rhamnosus GGB103 (8.76 ± 0.03 log CFU mL?1) was obtained in the product containing carrageenan–maltodextrin. The addition of guar–locust bean–carrageenan led to 20‐fold increase in the level of β‐galactosidase activity for L. rhamnosus GGB101 (1208 ± 2.12 Miller units mL?1) compared to the control (61 ± 2.83 Miller units mL?1). Our results suggested that gums could be added to milk to improve viability and enhance β‐galactosidase activity of Lactobacillus. 相似文献
78.
79.
80.
Yuanyuan Zhang Haiyan Lu Bing Wang Zhuo Zhang Xiaorong Lin Zhongzheng Chen Bin Li 《International Journal of Food Science & Technology》2015,50(6):1397-1404
Removal of imidacloprid and acetamiprid in tea infusions by microfiltration membrane using dead‐end model was investigated in the present study. The results showed that microfiltration significantly promoted the removal of both pesticides (P < 0.05) in tea infusions. Furthermore, the extent of removal was strongly influenced by the pore size of membrane, operational pressure and the concentrations of tea infusions. The initial concentration of imidacloprid and acetamiprid showed no significant effect on their removal rates. The maximum removal rates were 79.7% for imidacloprid and 81.9% acetamiprid. The changes in major chemical components of tea infusions after microfiltration were evaluated. The results indicated that microfiltration caused no considerable changes in total polyphenols and total free amino acids, and small but statistically significant losses (6.3–18.0%) of eight catechins and three methylxanthines when filtration volume reached to 200 mL. The present study validated the application of microfiltration as a potentially feasible and promising method for the removal of imidacloprid and acetamiprid residues from tea infusions. 相似文献