全文获取类型
收费全文 | 2214篇 |
免费 | 211篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 33篇 |
综合类 | 1篇 |
化学工业 | 502篇 |
金属工艺 | 99篇 |
机械仪表 | 144篇 |
建筑科学 | 24篇 |
能源动力 | 81篇 |
轻工业 | 257篇 |
水利工程 | 6篇 |
石油天然气 | 2篇 |
无线电 | 432篇 |
一般工业技术 | 460篇 |
冶金工业 | 108篇 |
原子能技术 | 18篇 |
自动化技术 | 265篇 |
出版年
2023年 | 25篇 |
2022年 | 16篇 |
2021年 | 68篇 |
2020年 | 61篇 |
2019年 | 79篇 |
2018年 | 92篇 |
2017年 | 99篇 |
2016年 | 98篇 |
2015年 | 66篇 |
2014年 | 131篇 |
2013年 | 192篇 |
2012年 | 190篇 |
2011年 | 187篇 |
2010年 | 135篇 |
2009年 | 146篇 |
2008年 | 136篇 |
2007年 | 107篇 |
2006年 | 85篇 |
2005年 | 74篇 |
2004年 | 57篇 |
2003年 | 71篇 |
2002年 | 46篇 |
2001年 | 40篇 |
2000年 | 48篇 |
1999年 | 43篇 |
1998年 | 30篇 |
1997年 | 18篇 |
1996年 | 12篇 |
1995年 | 11篇 |
1994年 | 12篇 |
1993年 | 14篇 |
1992年 | 8篇 |
1991年 | 1篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1976年 | 3篇 |
排序方式: 共有2432条查询结果,搜索用时 15 毫秒
71.
Jin Kyung Song Duwoon Kim Jong-Bang Eun Byeong-Dae Choi Myung Joo Oh Sung Ju Jung 《Food science and biotechnology》2012,21(5):1405-1411
The edible ascidian, sea squirt Halocynthia roretzi (Drasche) is marine invertebrate that is a valuable source of foods and bioactive compounds. A severe disease of the sea squirt characterized by degeneration of tunic fibers formed of bundled cellulose microfibrils has occurred. We hypothesized that bacteria lyse the cellulose fibril structure, cellulase activity may be a causative agent of the disease. Among the bacteria isolated from diseased sea squirt, Pseudoalteromonas sp. NO3 had cellulase activity based on a Congo red overlay assay and starch-reducing activity. Sea squirts exhibited 40–100% cumulative mortality after injection with Pseudoalteromonas sp. NO3 using doses of 2×106?2×108 colony forming unit (CFU)/individual. Dead sea squirts possess thinner and ruptured tunics, which were similar to natural outbreaks. These results suggest that Pseudoalteromonas sp. NO3 possessing cellulase activity is one of the causes of tunic softness syndrome in sea squirt. 相似文献
72.
73.
Abstract: Hydrocarbons, gas compounds, and off‐odor volatiles were determined for irradiated (0 or 5 kGy) commercial sausages with different fat contents (16% and 29%) during a 60‐d storage period at 4 °C. Total of 4 hydrocarbons (C14:1, C15:0, C16:2, and C17:1) were detected only in irradiated sausages: the amount of C16:2 was the highest, followed by C17:1, C14:1, and C15:0. The concentrations of hydrocarbons decreased significantly (P < 0.05) with storage, but were still detectable at the end of 60‐d storage. Irradiated sausages produced significantly higher amounts of CO than the nonirradiated ones. CH4 was detected only in irradiated sausages. Dimethyl disulfide was detected only in irradiated sausages and its concentration decreased significantly (P < 0.05) with storage. Fat content of sausages showed a significant effect on the production and retention of hydrocarbons, gas compounds, and sulfur volatiles in irradiated sausages during storage. Some hydrocarbons (C16:2, C17:1, C14:1, and C15:0), CH4, and dimethyl disulfide were only found in irradiated sausages indicating that these compounds can be used as potential markers for irradiated sausages. 相似文献
74.
75.
Multimedia Tools and Applications - To catch up with the recent expansions of wireless platforms, the performance of quality management systems for wireless communication network services needs to... 相似文献
76.
Woo‐Hee Kim Min‐Kyu Kim Il‐Kwon Oh Wan Joo Maeng Taehoon Cheon Soo‐Hyun Kim Atif Noori David Thompson Schubert Chu Hyungjun Kim 《Journal of the American Ceramic Society》2014,97(4):1164-1169
Films of CeO2 were deposited by atomic layer deposition (ALD) using a Ce(mmp)4 [mmp = 1‐methoxy‐2‐methyl‐2‐propanolate] precursor and H2O reactant. The growth characteristics and film properties of ALD CeO2 were investigated. The ALD CeO2 process produced highly pure, stoichiometric films with polycrystalline cubic phases. Using the ALD CeO2 process, the effects of Ce doping into an HfO2 gate dielectric were systematically investigated. Regardless of Ce/(Ce + Hf) composition, all ALD CexHf1?xO2 films exhibited constant growth rates of approximately 1.3 Å/cycle, which is essentially identical to the ALD HfO2 growth rates. After high‐temperature vacuum annealing at 900°C, it was verified, based on X‐ray diffraction and high‐resolution cross‐sectional transmission electron microscopy results, that all samples with various Ce/(Ce + Hf) compositions were transformed from nanocrystalline to stabilized cubic or tetragonal HfO2 phases. In addition, the dielectric constant of the CexHf1?xO2 films significantly increased, depending on the Ce doping content. The maximum dielectric constant value was found to be nearly 39 for the Ce/(Ce + Hf) concentration of ~11%. 相似文献
77.
Park Joo Hyun Lee Jong-Woo Um Jong-Seok Yook Juhye Kim Kwangki Lim Soon-Bum 《The Journal of supercomputing》2021,77(6):6381-6407
The Journal of Supercomputing - Although Digital Accessible Information System, an international digital talking book standard, is conducting active research on upper level education for people... 相似文献
78.
79.
Bae Jin Lee Chang Wook Kang Seong-Joon Kim Suk Joo Bae 《The International Journal of Advanced Manufacturing Technology》2014,71(1-4):219-231
In this paper, we examine the preventive maintenance policies for systems/items which are degraded continuously in time and the degree of deterioration that can be observed through periodic inspection. The items will be replaced preventively if the wear process exceeds a limit at periodic inspection or replaced immediately on failure. The limit is assumed to be random in taking individual variation to withstand damages or unmeasurable variables latent to failure into account. Continuous wear process is modeled via a gamma process. We derive an optimal wear limit for preventive replacement so that the long-run total expected cost per unit time is minimized. The proposed method is applied to a problem of block mat inspection for the barrier’s seabed protection. 相似文献
80.
Investors in futures market used to employ trading system which depends on reference pattern (template) to detect real-time buy or sell signal from the market. Indeed they prepare in advance a number of reference patterns that market movement might follow, and then match the current market with one of reference patterns. One popular way to prepare templates is to fix a relatively small number of them which represent possible market movements efficiently. The underlying assumption of this approach is of course that the current market movement is close enough to one of the templates. However, there is always a calculated risk that the current market is close to none of them sufficiently. In this article we investigate the issue of appropriate number of templates (or template cardinality I) in terms of profitability. We will show that one may improve profitability by increasing I and that random pattern sampling plays a key role in such case. An empirical study is done on the Korean futures market. 相似文献