全文获取类型
收费全文 | 68217篇 |
免费 | 7102篇 |
国内免费 | 4168篇 |
专业分类
电工技术 | 5520篇 |
技术理论 | 4篇 |
综合类 | 5553篇 |
化学工业 | 9451篇 |
金属工艺 | 4330篇 |
机械仪表 | 4887篇 |
建筑科学 | 5465篇 |
矿业工程 | 2122篇 |
能源动力 | 2173篇 |
轻工业 | 4556篇 |
水利工程 | 1691篇 |
石油天然气 | 3433篇 |
武器工业 | 746篇 |
无线电 | 7863篇 |
一般工业技术 | 7229篇 |
冶金工业 | 2975篇 |
原子能技术 | 857篇 |
自动化技术 | 10632篇 |
出版年
2024年 | 304篇 |
2023年 | 1031篇 |
2022年 | 1962篇 |
2021年 | 2715篇 |
2020年 | 2016篇 |
2019年 | 1703篇 |
2018年 | 1997篇 |
2017年 | 2111篇 |
2016年 | 2043篇 |
2015年 | 2822篇 |
2014年 | 3712篇 |
2013年 | 4262篇 |
2012年 | 4998篇 |
2011年 | 5391篇 |
2010年 | 4854篇 |
2009年 | 4580篇 |
2008年 | 4647篇 |
2007年 | 4545篇 |
2006年 | 4200篇 |
2005年 | 3636篇 |
2004年 | 2690篇 |
2003年 | 2267篇 |
2002年 | 2323篇 |
2001年 | 2027篇 |
2000年 | 1527篇 |
1999年 | 1200篇 |
1998年 | 751篇 |
1997年 | 645篇 |
1996年 | 605篇 |
1995年 | 448篇 |
1994年 | 336篇 |
1993年 | 239篇 |
1992年 | 229篇 |
1991年 | 144篇 |
1990年 | 113篇 |
1989年 | 99篇 |
1988年 | 72篇 |
1987年 | 55篇 |
1986年 | 43篇 |
1985年 | 20篇 |
1984年 | 19篇 |
1983年 | 13篇 |
1982年 | 16篇 |
1981年 | 10篇 |
1980年 | 18篇 |
1979年 | 15篇 |
1974年 | 6篇 |
1973年 | 3篇 |
1959年 | 4篇 |
1951年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 14 毫秒
11.
12.
13.
Dongdong Ji Zheng Liu Bailing Jiang Xiaofei Luo 《International Journal of Hydrogen Energy》2021,46(27):13960-13970
The evaluation of cell's weatherability is of practical interest. To further improve the soluble lead flow battery's weatherability, physiochemical properties of electrolytes containing fluoborate, perchlorate, methanesulfonate and trifluoromethanesulfonate are investigated from ?60 to 50 °C. Activities of CF3SO3H and HClO4 are poor in trifluoromethanesulfonate and perchlorate solutions due to common anion effect. The solubility of lead salt can be improved by increasing temperature, but worsened by increasing acid's content. With the temperature increasing, the conductivity is enhanced, and the viscosity is lowered for four solutions. The same results have been found by increasing acid's content except for CF3SO3H. The high energy efficiency can be achieved for cells over ?40–0 °C using fluoborate and perchlorate solutions, 73.2% at ?40 °C and 78.1% at ?30 °C respectively. Over the temperature range of 20–50 °C, the cells with methanesulfonate and trifluoromethanesulfonate solutions have good performance, 77.4% and 73.7% at 50 °C respectively. 相似文献
14.
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
15.
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
16.
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
17.
18.
19.
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
20.
Priyadarshi Chakraborty Yiming Tang Tomoya Yamamoto Yifei Yao Tom Guterman Shai Zilberzwige-Tal Nofar Adadi Wei Ji Tal Dvir Ayyalusamy Ramamoorthy Guanghong Wei Ehud Gazit 《Advanced materials (Deerfield Beach, Fla.)》2020,32(9):1906043
Self-assembled peptide hydrogels represent the realization of peptide nanotechnology into biomedical products. There is a continuous quest to identify the simplest building blocks and optimize their critical gelation concentration (CGC). Herein, a minimalistic, de novo dipeptide, Fmoc-Lys(Fmoc)-Asp, as an hydrogelator with the lowest CGC ever reported, almost fourfold lower as compared to that of a large hexadecapeptide previously described, is reported. The dipeptide self-assembles through an unusual and unprecedented two-step process as elucidated by solid-state NMR and molecular dynamics simulation. The hydrogel is cytocompatible and supports 2D/3D cell growth. Conductive composite gels composed of Fmoc-Lys(Fmoc)-Asp and a conductive polymer exhibit excellent DNA binding. Fmoc-Lys(Fmoc)-Asp exhibits the lowest CGC and highest mechanical properties when compared to a library of dipeptide analogues, thus validating the uniqueness of the molecular design which confers useful properties for various potential applications. 相似文献