全文获取类型
收费全文 | 91254篇 |
免费 | 9619篇 |
国内免费 | 5766篇 |
专业分类
电工技术 | 7210篇 |
技术理论 | 2篇 |
综合类 | 7373篇 |
化学工业 | 13538篇 |
金属工艺 | 5442篇 |
机械仪表 | 6224篇 |
建筑科学 | 7133篇 |
矿业工程 | 2610篇 |
能源动力 | 2854篇 |
轻工业 | 6744篇 |
水利工程 | 2003篇 |
石油天然气 | 4535篇 |
武器工业 | 1119篇 |
无线电 | 11109篇 |
一般工业技术 | 10203篇 |
冶金工业 | 3524篇 |
原子能技术 | 1174篇 |
自动化技术 | 13842篇 |
出版年
2024年 | 408篇 |
2023年 | 1414篇 |
2022年 | 2564篇 |
2021年 | 3741篇 |
2020年 | 2841篇 |
2019年 | 2420篇 |
2018年 | 2655篇 |
2017年 | 2917篇 |
2016年 | 2728篇 |
2015年 | 3885篇 |
2014年 | 4756篇 |
2013年 | 5725篇 |
2012年 | 6266篇 |
2011年 | 6763篇 |
2010年 | 6274篇 |
2009年 | 6065篇 |
2008年 | 5829篇 |
2007年 | 5624篇 |
2006年 | 5454篇 |
2005年 | 4638篇 |
2004年 | 3401篇 |
2003年 | 3209篇 |
2002年 | 3431篇 |
2001年 | 3020篇 |
2000年 | 2226篇 |
1999年 | 1794篇 |
1998年 | 1213篇 |
1997年 | 1046篇 |
1996年 | 968篇 |
1995年 | 793篇 |
1994年 | 571篇 |
1993年 | 449篇 |
1992年 | 384篇 |
1991年 | 250篇 |
1990年 | 214篇 |
1989年 | 164篇 |
1988年 | 140篇 |
1987年 | 83篇 |
1986年 | 76篇 |
1985年 | 46篇 |
1984年 | 26篇 |
1983年 | 25篇 |
1982年 | 35篇 |
1981年 | 23篇 |
1980年 | 19篇 |
1979年 | 13篇 |
1974年 | 8篇 |
1973年 | 7篇 |
1959年 | 7篇 |
1951年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Lü Qing Xu Bin Yu Yang Zhan Wei Zhao Yu Zheng Jun Ji Jian 《Bulletin of Engineering Geology and the Environment》2021,80(8):6513-6525
Bulletin of Engineering Geology and the Environment - Many uncertainties exist in pile-stabilized slopes which make their design substantially complicated. In this paper, a first-order reliability... 相似文献
22.
Yude Ji Yanping Guo Yuejuan Liu Yun Tian 《International Journal of Adaptive Control and Signal Processing》2020,34(3):283-297
This article focuses on the consensus problem of leader-following fractional-order multi-agent systems (MASs) with general linear and Lipschitz nonlinear dynamics. First, the distributed adaptive protocols for linear and nonlinear fractional-order MASs are constructed, respectively. We allow the control coupling gains to be time varying for each agent. Moreover, the adaptive modification schemes for the control gain are designed, which renders smaller control gains and thus requires smaller amplitude on the control input without sacrificing consensus convergence. Second, based on fractional-order Lyapunov stability theorem and Barbalat's lemma, two novel sufficient conditions in terms of linear matrix inequalities are provided to ensure that the leader-following consensus can be obtained in the case for any undirected connected communication graph. Furthermore, we show that the proposed algorithm also works for consensus of agents with intrinsic Lipschitz nonlinear dynamics. As a result, the proposed framework requires no global information and thus can be implemented in a fully distributed manner. Finally, the numerical simulations are given to demonstrate the effectiveness of obtained the theoretical results. 相似文献
23.
为了避免回收单一钕铁硼废料中有价元素带来的操作复杂和资源浪费等问题,本研究采用共沉淀法共沉淀出钕铁硼废料中的有价元素Me(Nd,Pr,Co,Fe),制备可用于生产再生钕铁硼的原料;根据质量守恒和同时平衡原理,采用MATLAB软件建立Me(Nd,Pr,Co,Fe)-OH--NH3热力学模型,绘制lg[Me]-p H曲线模拟共沉淀工艺,并根据模拟结果确立了共沉淀工艺;模拟和实验的结果表明:根据lg[Me]-p H模拟结果可以确立一步共沉淀法的p H:6~10,Fe3+比Fe2+更易于沉淀完全;在上述条件下获得的共沉淀粉末主相均为Nd,Pr,Co,Fe的化合物,且有价元素的百分比含量均大于99.4%;其中,当p H值在8左右时回收率最高,在该条件下金属元素Me(Nd,Pr,Co,Fe)的沉淀效率分别为:98.7%,99.9%,93.6%,99.9%。该结果也表明共沉淀法工艺不仅高效,而且所制备的共沉淀粉末可以满足制备二次钕铁硼的需要。 相似文献
24.
25.
In vivo Kinetic Biodistribution of Nano‐Sized Outer Membrane Vesicles Derived from Bacteria
下载免费PDF全文
![点击此处可从《Small (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Su Chul Jang Sae Rom Kim Yae Jin Yoon Kyong‐Su Park Ji Hyun Kim Jaewook Lee Oh Youn Kim Eun‐Jeong Choi Dae‐Kyum Kim Dong‐Sic Choi Yoon‐Keun Kim Jaesung Park Dolores Di Vizio Yong Song Gho 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(4):456-461
Evaluation of kinetic distribution and behaviors of nanoparticles in vivo provides crucial clues into their roles in living organisms. Extracellular vesicles are evolutionary conserved nanoparticles, known to play important biological functions in intercellular, inter‐species, and inter‐kingdom communication. In this study, the first kinetic analysis of the biodistribution of outer membrane vesicles (OMVs)—bacterial extracellular vesicles—with immune‐modulatory functions is performed. OMVs, injected intraperitoneally, spread to the whole mouse body and accumulate in the liver, lung, spleen, and kidney within 3 h of administration. As an early systemic inflammation response, increased levels of TNF‐α and IL‐6 are observed in serum and bronchoalveolar lavage fluid. In addition, the number of leukocytes and platelets in the blood is decreased. OMVs and cytokine concentrations, as well as body temperature are gradually decreased 6 h after OMV injection, in concomitance with the formation of eye exudates, and of an increase in ICAM‐1 levels in the lung. Following OMV elimination, most of the inflammatory signs are reverted, 12 h post‐injection. However, leukocytes in bronchoalveolar lavage fluid are increased as a late reaction. Taken together, these results suggest that OMVs are effective mediators of long distance communication in vivo. 相似文献
26.
27.
在目前市场需求呈现规模扩张和品类个性化的冲击下,制造业面对的竞争压力愈发明显.且随着新时代自动化、信息化、大数据智能化等先进制造特征的兴起,更加促使制造业向转型升级不断进军.以空调制造业的控制器版块为例,从制约此单位效率的SMT车间切换浪费为切入点,在SMED快速换模的理念基础上,通过使用IE分析工具对切换流程进行研究,提炼出一套多模组固定料站切换模型,同时结合自动化、信息化等智能制造技术引进,完成SMT车间人力投入减少35人,日均产出点数提升18.29%,设备运行率提升15.46%,综合成本降低110.6万元/年的效益.成功推广应用至电子物料拣选版块,并开发信息化看板,夯实应用效益,再次证实"多模组固定料站"快速切换模型是典型小、多、高生产模式,具有可行性的解决方案. 相似文献
28.
Wireless Personal Communications - The purpose of this study is to construct a structural equation model of shared bicycle added psychological factors proceeding from the theory of planned... 相似文献
29.
30.
Anxiang Su Gaoxing Ma Minhao Xie Yang Ji Xiangfei Li Liyan Zhao Qiuhui Hu 《International Journal of Food Science & Technology》2019,54(6):2277-2287
In this study, in vitro digestion and fermentation of Flammulina velutipes -derived polysaccharides (FVP) were investigated. It was found that FVP mainly consisted of 48.45% glucose, 15.40% mannose, 14.60% xylose, 11.80% fucose and 9.90% galactose. The -human saliva, simulated gastric and small intestinal juices conditions did not break down the FVP. Based on in vitro fermentation tests, FVP modulated the composition of gut microbiota by elevating the amounts of Bifidobacteriaceae and Bacteroidaceae and reducing the numbers of genera Lachnospiraceae and Enterococcaceae. Meanwhile, FVP affected the synthesis of short-chain fatty acids derived from gut microbiota. 相似文献