全文获取类型
收费全文 | 149014篇 |
免费 | 16840篇 |
国内免费 | 11479篇 |
专业分类
电工技术 | 13569篇 |
技术理论 | 2篇 |
综合类 | 14146篇 |
化学工业 | 18546篇 |
金属工艺 | 10321篇 |
机械仪表 | 10626篇 |
建筑科学 | 11234篇 |
矿业工程 | 5203篇 |
能源动力 | 4144篇 |
轻工业 | 13316篇 |
水利工程 | 4864篇 |
石油天然气 | 6358篇 |
武器工业 | 2115篇 |
无线电 | 16966篇 |
一般工业技术 | 13832篇 |
冶金工业 | 7365篇 |
原子能技术 | 2503篇 |
自动化技术 | 22223篇 |
出版年
2024年 | 794篇 |
2023年 | 2121篇 |
2022年 | 4989篇 |
2021年 | 6691篇 |
2020年 | 4849篇 |
2019年 | 3566篇 |
2018年 | 3841篇 |
2017年 | 4663篇 |
2016年 | 4225篇 |
2015年 | 6398篇 |
2014年 | 8091篇 |
2013年 | 9486篇 |
2012年 | 11988篇 |
2011年 | 12630篇 |
2010年 | 12252篇 |
2009年 | 11489篇 |
2008年 | 11724篇 |
2007年 | 11157篇 |
2006年 | 9862篇 |
2005年 | 8054篇 |
2004年 | 5906篇 |
2003年 | 4695篇 |
2002年 | 4766篇 |
2001年 | 4211篇 |
2000年 | 2879篇 |
1999年 | 1586篇 |
1998年 | 951篇 |
1997年 | 731篇 |
1996年 | 584篇 |
1995年 | 441篇 |
1994年 | 339篇 |
1993年 | 266篇 |
1992年 | 173篇 |
1991年 | 142篇 |
1990年 | 134篇 |
1989年 | 134篇 |
1988年 | 67篇 |
1987年 | 60篇 |
1986年 | 49篇 |
1985年 | 24篇 |
1984年 | 17篇 |
1983年 | 21篇 |
1982年 | 20篇 |
1981年 | 30篇 |
1980年 | 36篇 |
1979年 | 22篇 |
1977年 | 44篇 |
1976年 | 81篇 |
1959年 | 18篇 |
1951年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
In vivo Kinetic Biodistribution of Nano‐Sized Outer Membrane Vesicles Derived from Bacteria 下载免费PDF全文
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
2.
Private information retrieval(PIR) is an important privacy protection issue of secure multi-party computation, but the PIR protocols based on classical cryptography are vulnerable because of new technologies,such as quantum computing and cloud computing. The quantum private queries(QPQ) protocols available, however, has a high complexity and is inefficient in the face of large database. This paper, based on the QKD technology which is mature now, proposes a novel QPQ protocol utilizing the key dilution and auxiliary parameter. Only N quits are required to be sent in the quantum channel to generate the raw key, then the straight k bits in the raw key are added bitwise to dilute the raw key, and a final key is consequently obtained to encrypt the database. By flexible adjusting of auxiliary parameters θ and k, privacy is secured and the query success ratio is improved. Feasibility and performance analyses indicate that the protocol has a high success ratio in first-trial query and is easy to implement, and that the communication complexity of O(N) is achieved. 相似文献
3.
4.
5.
6.
根据我国煤炭样品制备技术现状和国内外发展趋势,研究开发了自动化控制无人值守煤炭联合制样系统,并从系统制样程序设计、系统整体结构设计、各单元模块设计、系统性能试验等方面对该系统的主要功能及软硬件结构进行介绍,并从称重单元、输送单元、破碎单元、缩分单元、干燥单元、粉碎单元、样品接收包装单元、除尘清洗单元等重点阐述了各单元模块设计,可实现煤样制备全过程无人化、信息化及样品的安全可追溯,其性能试验符合国标GB 474—2008中的相应要求。 相似文献
7.
测向误差的减小一直以来都是无线电测向精度提高的一个难点,对于不同的测向体制所采用的减小测向误差的方法都不尽相同。本文主要介绍的是相关干涉仪测向体制的基本原理以及通过内插法的应用来减小测向误差的方法。 相似文献
8.
9.
10.
Shuang Shao Yong Liu Chun-Shui Xu Ying-Xuan Xu Bin Wu Xiao-Shu Zeng Xian-Feng Lu Xiang-Jie Yang 《金属学报(英文版)》2015,(1):7-14
The microstructure and mechanical properties of Mg–6Zn–1Y and Mg–6Zn–3Y(wt%) alloys under different cooling rates were investigated. The results show that the second dendrite arm spacing(SDAS) of Mg–6Zn–1Y and Mg–6Zn–3Y is reduced by 32 and 30% with increasing cooling rates(Rc) from 10.2 to 23 K/s, which can be predicted using a empirical model of SDAS=68 R 0:45:45cand SDAS=73 R 0c, respectively. The compressive strength of both alloys increases with increasing the cooling rate, which is attributed to the increase of volume fraction(Vf) of secondary phases under high cooling rate. The interaction of the cooling rate and component with SDAS has been theoretically analyzed using interdependence theory. 相似文献