全文获取类型
收费全文 | 343834篇 |
免费 | 9765篇 |
国内免费 | 3690篇 |
专业分类
电工技术 | 9432篇 |
技术理论 | 9篇 |
综合类 | 4936篇 |
化学工业 | 52170篇 |
金属工艺 | 14596篇 |
机械仪表 | 13676篇 |
建筑科学 | 13028篇 |
矿业工程 | 3037篇 |
能源动力 | 8821篇 |
轻工业 | 27673篇 |
水利工程 | 3984篇 |
石油天然气 | 8358篇 |
武器工业 | 556篇 |
无线电 | 44791篇 |
一般工业技术 | 60941篇 |
冶金工业 | 50945篇 |
原子能技术 | 6234篇 |
自动化技术 | 34102篇 |
出版年
2022年 | 3158篇 |
2021年 | 5040篇 |
2020年 | 3804篇 |
2019年 | 4007篇 |
2018年 | 5644篇 |
2017年 | 5987篇 |
2016年 | 6017篇 |
2015年 | 5219篇 |
2014年 | 8010篇 |
2013年 | 16264篇 |
2012年 | 11741篇 |
2011年 | 14333篇 |
2010年 | 11834篇 |
2009年 | 12501篇 |
2008年 | 13068篇 |
2007年 | 12932篇 |
2006年 | 12380篇 |
2005年 | 11209篇 |
2004年 | 9597篇 |
2003年 | 9189篇 |
2002年 | 8525篇 |
2001年 | 8454篇 |
2000年 | 8412篇 |
1999年 | 8768篇 |
1998年 | 16546篇 |
1997年 | 12108篇 |
1996年 | 9796篇 |
1995年 | 7812篇 |
1994年 | 6874篇 |
1993年 | 6430篇 |
1992年 | 5181篇 |
1991年 | 4729篇 |
1990年 | 4435篇 |
1989年 | 4121篇 |
1988年 | 3929篇 |
1987年 | 3328篇 |
1986年 | 3212篇 |
1985年 | 3709篇 |
1984年 | 3465篇 |
1983年 | 3087篇 |
1982年 | 2905篇 |
1981年 | 2995篇 |
1980年 | 2797篇 |
1979年 | 2675篇 |
1978年 | 2511篇 |
1977年 | 2977篇 |
1976年 | 3566篇 |
1975年 | 2330篇 |
1974年 | 2321篇 |
1973年 | 2326篇 |
排序方式: 共有10000条查询结果,搜索用时 671 毫秒
61.
62.
To improve the convertibility of reconfigurable manufacturing system (RMS), the concept of delayed reconfigurable manufacturing system (D-RMS) was proposed. RMS and D-RMS are both constructed around part family. However, D-RMS may suffer from ultra-long system problem with unacceptable idle machines using generic RMS part families. Besides, considering the complex basic system structure of D-RMS, machine selection of D-RMS should be addressed, including dedicated machine, flexible machine, and reconfigurable machine. Therefore, a system design method for D-RMS based on part family grouping and machine selection is proposed. Firstly, a part family grouping method is proposed for D-RMS that groups the parts with more former common operations into the same part family. The concept of longest relative position common operation subsequence (LPCS) is proposed. The similarity coefficient among the parts is calculated based on LPCS. The reciprocal value of the operation position of LPCS is adopted as the characteristic value. The average linkage clustering (ALC) algorithm is used to cluster the parts. Secondly, a machine selection method is proposed to complete the system design of D-RMS, including machine selection rules and the dividing point decision model. Finally, a case study is given to implement and verify the proposed system design method for D-RMS. The results show that the proposed system design method is effective, which can group parts with more former common operations into the same part family and select appropriate machine types. 相似文献
63.
既有公共建筑能耗中,围护结构节能潜力巨大。以兰州某既有办公建筑为例,采用DeST-C软件模拟围护结构不同材料厚度、窗型,得出系列负荷,通过对数据分析、比较,得出如下结论:外墙外保温适宜材料为50mm的挤塑板,最大热负荷节能率为45.66%;屋面适宜保温材料为65mm的挤塑板,最大热负荷节能率为4.25%;外窗各个朝向全部更换玻璃,推荐选用内张膜中空玻璃(双膜),最大热负荷节能率为7.36%;单独更换南向外窗材料,推荐选用真空镀膜复合中空玻璃,最大热负荷节能率为1.78%。 相似文献
64.
Lin Haicheng Huang Wantong Zhao Kun Qiao Shuang Liu Zheng Wu Jian Chen Xi Ji Shuai-Hua 《Nano Research》2020,13(1):133-137
Nano Research - The isostructural and isoelectronic transition-metal-dichalcogenides 1T-TaS2 and 1T-TaSe2 are layered materials with intricate electronic structures. Combining the molecular beam... 相似文献
65.
66.
67.
68.
Pasquale Stano Tereza Pereira de Souza Paolo Carrara Emiliano Altamura Erica D’Aguanno Margherita Caputo 《先进材料力学与结构力学》2015,22(9):748-759
Here we report some recent biophysical issues on the preparation of solute-filled lipid vesicles and their relevance to the construction of “synthetic cells.” First, we introduce the “semi-synthetic minimal cells” as the liposome-based cell-like systems, which contain a minimal number of biomolecules required to display simple and complex biological functions. Next, we focus on recent aspects related to the construction of synthetic cells. Emphasis is given to the interplay between the methods of synthetic cell preparation and the physics of solute encapsulation. We briefly introduce the notion of structural and compositional “diversity” in synthetic cell populations. 相似文献
69.
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
70.