全文获取类型
收费全文 | 808142篇 |
免费 | 30200篇 |
国内免费 | 12338篇 |
专业分类
电工技术 | 24851篇 |
技术理论 | 31篇 |
综合类 | 17928篇 |
化学工业 | 128239篇 |
金属工艺 | 36366篇 |
机械仪表 | 33485篇 |
建筑科学 | 35449篇 |
矿业工程 | 11790篇 |
能源动力 | 22327篇 |
轻工业 | 63491篇 |
水利工程 | 9971篇 |
石油天然气 | 29554篇 |
武器工业 | 2271篇 |
无线电 | 90588篇 |
一般工业技术 | 134633篇 |
冶金工业 | 118113篇 |
原子能技术 | 13349篇 |
自动化技术 | 78244篇 |
出版年
2023年 | 5751篇 |
2022年 | 11025篇 |
2021年 | 16207篇 |
2020年 | 11915篇 |
2019年 | 11725篇 |
2018年 | 15825篇 |
2017年 | 16696篇 |
2016年 | 15810篇 |
2015年 | 16597篇 |
2014年 | 22832篇 |
2013年 | 40202篇 |
2012年 | 32145篇 |
2011年 | 39236篇 |
2010年 | 32290篇 |
2009年 | 33341篇 |
2008年 | 33277篇 |
2007年 | 32548篇 |
2006年 | 31247篇 |
2005年 | 28150篇 |
2004年 | 22488篇 |
2003年 | 21148篇 |
2002年 | 19780篇 |
2001年 | 19168篇 |
2000年 | 18828篇 |
1999年 | 20977篇 |
1998年 | 39424篇 |
1997年 | 28570篇 |
1996年 | 22781篇 |
1995年 | 17458篇 |
1994年 | 14959篇 |
1993年 | 13552篇 |
1992年 | 10012篇 |
1991年 | 8988篇 |
1990年 | 8410篇 |
1989年 | 7930篇 |
1988年 | 7211篇 |
1987年 | 6279篇 |
1986年 | 6041篇 |
1985年 | 6525篇 |
1984年 | 6079篇 |
1983年 | 5288篇 |
1982年 | 5030篇 |
1981年 | 5052篇 |
1980年 | 4773篇 |
1979年 | 4633篇 |
1978年 | 4410篇 |
1977年 | 5334篇 |
1976年 | 6971篇 |
1975年 | 3796篇 |
1973年 | 3665篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
Journal of Computer and Systems Sciences International - It is shown that the Lyapunov theorem on the distribution properties of the sum of random variables with different distribution densities... 相似文献
6.
Multimedia Tools and Applications - Mammograms are the images used by radiologists to diagnose breast cancer. Breast cancer is one of the most common cancers in women. The early detection of breast... 相似文献
7.
8.
Peng Wang Yan Li Yujiao Qu Baowei Wang Jingxin Sun Chunwei Miao Ming Huang He Huang Congxiang Zhang 《International Journal of Food Science & Technology》2022,57(6):3428-3439
The effects of cellulose microfibres (CMFs, Average size: 100 ± 5 μm) and cellulose nanofibres (CNFs, Average size: 60 ± 3 nm) on the properties of myofibrillar protein (MP) gels from duck breast meat were studied. The results demonstrated that CMFs and CNFs were mostly connected to MP by non-covalent bonds, the diffusion and cross-linking of MP molecules was promoted, and a denser and more complete gel network was formed. With the increases of CMFs and CNFs concentration (0–10%), the hardness was increased by 13.15% and 19.78% for CMFs10% and CNFs10% gels, respectively, and the elasticity was increased by 40% and 80%, respectively. At the same concentration (0–10%), the increase in gel hardness, viscoelasticity and immobilised water content was greater in the CNFs-MP group than in the CMFs-MP group. The CNFs-MP group had a tighter gel network, and CNFs had a better potential to improve the gelation performance of MP. 相似文献
9.
Sinan Zhang Yadonga Zhao Xueshuang Yao Zhenhong Zheng Chuyao Zheng Zhuo Jiang 《International Journal of Food Science & Technology》2022,57(7):4245-4253
Ripe carambolas are hard to store and transport, while freeze-dried ones are easy to store. However, its long production time leads to higher costs. This study shows that high hydrostatic pressure (HHP) treatment could shorten the freeze-drying time of carambola slices. After HHP treatment (25–250 MPa), the drying time of the fresh sample can be shortened by 33.3–44.4% and the distribution of water and pigment in tissues is much uniform. With the increment of the pressure, 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical scavenging rate are increased. At 250 MPa, the total phenolic content (TPC) increased from 11.34 to 13.36 mg GAE g−1, and the total flavonoid content (TFC) of the control sample was increased from 10.77 to 12.73 mg RE g−1. Compared with the untreated sample, HHP treatment can enhance the flavour and shorten the freeze-drying time. This work guides the application of HHP technology for drying food processing. 相似文献
10.
Mengru Liu Weihai Zhang Limin Ma 《International Journal of Adaptive Control and Signal Processing》2022,36(1):69-87
The article investigates the finite-time adaptive fuzzy control for a class of nonlinear systems with output constraint and input dead-zone. First, by skillfully combining the barrier Lyapunov function, backstepping design method, and finite-time control theory, a novel adaptive state-feedback tracking controller is constructed, and the output constraint of the nonlinear system is not violated. Second, the fuzzy logic system is used to approximate unknown function in the nonlinear system. Third, the finite-time command filter is introduced to avoid the problem of “complexity explosion” caused by repeated differentiations of the virtual control signal in conventional backstepping control schemes. Meanwhile, a new saturation function is added in the compensating signal for filter error to improve control accuracy. Finally, based on Lyapunov stability analysis, all the signals of the closed-loop are proved to be semi-globally uniformly ultimately bounded, and the tracking error converges to a small neighborhood region of the origin in a finite time. A simulation example is presented to demonstrate the effectiveness for the proposed control scheme. 相似文献