全文获取类型
收费全文 | 10989篇 |
免费 | 1119篇 |
国内免费 | 531篇 |
专业分类
电工技术 | 649篇 |
技术理论 | 2篇 |
综合类 | 839篇 |
化学工业 | 1766篇 |
金属工艺 | 607篇 |
机械仪表 | 710篇 |
建筑科学 | 884篇 |
矿业工程 | 257篇 |
能源动力 | 323篇 |
轻工业 | 1128篇 |
水利工程 | 248篇 |
石油天然气 | 456篇 |
武器工业 | 86篇 |
无线电 | 1186篇 |
一般工业技术 | 1275篇 |
冶金工业 | 454篇 |
原子能技术 | 105篇 |
自动化技术 | 1664篇 |
出版年
2024年 | 52篇 |
2023年 | 249篇 |
2022年 | 400篇 |
2021年 | 558篇 |
2020年 | 456篇 |
2019年 | 326篇 |
2018年 | 360篇 |
2017年 | 406篇 |
2016年 | 358篇 |
2015年 | 494篇 |
2014年 | 602篇 |
2013年 | 680篇 |
2012年 | 789篇 |
2011年 | 770篇 |
2010年 | 666篇 |
2009年 | 650篇 |
2008年 | 667篇 |
2007年 | 505篇 |
2006年 | 532篇 |
2005年 | 452篇 |
2004年 | 329篇 |
2003年 | 395篇 |
2002年 | 384篇 |
2001年 | 328篇 |
2000年 | 206篇 |
1999年 | 235篇 |
1998年 | 151篇 |
1997年 | 137篇 |
1996年 | 113篇 |
1995年 | 88篇 |
1994年 | 82篇 |
1993年 | 54篇 |
1992年 | 47篇 |
1991年 | 33篇 |
1990年 | 24篇 |
1989年 | 19篇 |
1988年 | 14篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 4篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1959年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
992.
Zhao‐Sheng Cai Zhan‐Qian Song Chun‐Sheng Yang Shi‐Bin Shang Yan‐Bai Yin 《应用聚合物科学杂志》2009,111(6):3010-3015
N,O‐(2‐carboxyethyl)chitosan (N,O‐2‐CEC) was prepared from chitosan with 3‐chloropropionic acid as modifying agent and NaOH as binding‐acid agent. 2‐Hydroxypropyl dimethylbenzylammonium N,O‐(2‐carboxyethyl) chitosan chloride (HPDMBA‐CEC) was obtained by the reaction of N,O‐2‐CEC with glycidyl dimethyl benzyl ammonium chloride (GDMBA) using NaOH as catalyst. The structures of chitosan derivatives were characterized by FTIR, 1H NMR, and gel permeation chromatography. The antimicrobial activity of HPDMBA‐CEC was evaluated against a Gram‐negative bacterium Escherichia coli (E.coli) and a Gram‐positive bacterium Staphylococcus aureus (S. aureus). Compared with CTS, N,O‐2‐CEC, and HPDMBA‐CTS, HPDMBA‐CEC had much stronger antimicrobial activity, and this activity increased with increasing substitution degree of quaternary ammonium group (DQ). When the substitution degree of carboxyethylation (DS of CE) was 0.72 and DQ was 0.60, the minimum inhibitory concentrations (MICs) of HPDMBA‐CEC were 3.1 and 6.3 μg/mL against S. aureus and E. coli, respectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
993.
工控软件中应用多线程技术的研究 总被引:2,自引:0,他引:2
本文概述了工控软件中应用多线程技术的原因,并进而论述了线程与进程的区别,线程的创建,终止,优先级及MFC类库对多线程技术的支持最后,本文提出了用MFC类库开发工控软件时采用多线程技术所遇到的问题,并给出解决方案。 相似文献
994.
不锈钢容器及管道的局部腐蚀 总被引:3,自引:0,他引:3
针对在化工行业中局部腐蚀的危险性,本文着重介绍了局部腐蚀中的晶间腐蚀和应力腐蚀发生的条件、机理以及防范的措施。 相似文献
995.
Fanan Wei Chao Yin Jianghong Zheng Ziheng Zhan Ligang Yao 《IET nanobiotechnology / IET》2019,13(7):651
By integrating organic parts achieved through evolution and inorganic parts developed by human civilisation, the cyborg microrobot is rising by taking advantage of the high flexibility, outstanding energy efficiency, extremely exquisite structure in the natural components and the fine upgradability, nice controllability in the artefact parts. Compared to the purely synthetic microrobots, the cyborg microrobots, due to the exceptional biocompatibility and biodegradability, have already been utilised in in situ diagnosis, precise therapy and other biomedical applications. In this review, through a thorough summary of recent advances of cyborg microrobots, the authors categorise the cyborg microrobots into four major classes according to the configuration between biomaterials and artefact materials, i.e. microrobots integrated inside living cell, microrobots modified with biological debris, microrobots integrated with single cell and microrobots incorporated with multiple cells. Cyborg microrobots with the four types of configurations are introduced and summarised with the combination approaches, actuation mechanisms, applications and challenges one by one. Moreover, they conduct a comparison among the four different cyborg microrobots to guide the actuation force promotion, locomotion control refinement and future applications. Finally, conclusions and future outlook of the development and potential applications of the cyborg microrobots are discussed.Inspec keywords: medical robotics, cellular biophysics, mobile robots, molecular biophysics, polymers, microrobotsOther keywords: locomotion control refinement, actuation force promotion, combination approaches, biological debris, living cell, artefact materials, biomaterials, biomedical applications, biodegradability, exceptional biocompatibility, natural components, energy efficiency, human civilisation, purely synthetic microrobots, cyborg microrobot 相似文献
996.
Xulin Yang Zicheng Wang Yingqing Zhan Jian Yang Yanke Zou Rui Zhao Xiaobo Liu 《Polymer International》2013,62(4):629-637
The different filler effects of identical nitrile‐functionalized carbon nanotubes (CNTs) and graphene nanoplatelets (GNs) in a poly(arylene ether nitrile) (PEEN) matrix were investigated. PEEN/CNT and PEEN/GN composites were prepared by a facile solution‐casting method and systematically investigated for their differences in morphological, thermal and rheological properties. In the PEEN matrix GNs contact one another in a plane‐to‐plane manner, while CNTs are separated. Compared with PEEN/CNT composites, PEEN/GN composites below 2 wt% filler content exhibited higher thermal stability. Rheological properties of the resulting composites indicated that PEEN/GN composites were more sensitive to strain and exhibited higher η*, G′ and G″ than PEEN/CNT composites. The rheological percolation for CNTs is over 2 wt%, higher than that for GNs (around 1 wt%). All these differences originate from the different dimensions and structures of CNTs and GNs: GNs with a flake‐like structure and larger surface area can have stronger physical and interfacial interactions with the polymer matrix. This work gives a comparative view of the different filler effects that functionalized CNTs and GNs can have in the polymer host. With identical processing technology, GNs can show a stronger filler effect than CNTs. © 2012 Society of Chemical Industry 相似文献
997.
In this paper, the electrochemical behavior of the reduction products in solution for Li/S cell is studied by UV-visual spectroscopy and electrochemical impedance spectroscopy (EIS). The results tell that the redox process of the polysulfide intermediate contains five charge-transfer steps in the practical Li/S cell. The formation of final reduction product of Li2S and the final re-oxidation product of S8 is completely irreversible. The transform between polysulfide and Li2S2 is electrochemical sluggish. The peaks corresponding to transformation Li2Sx ↔ Li2Sy (2 < x < y ≤ 6) are still symmetrical in spite of an increasing polarization with the proceeding of CV scan. While the redox process corresponding to Li2Sm ↔ Li2Sn (4 < m < n ≤ 8) is reversible. The dissolution long-chain polysulfide and deposition of short-chain polysulfide contribute mostly to the electrode deterioration even electrode blockage. Therefore, homogeneous mixing element sulfur with conductive components and alleviating the polysulfide dissolution are equally important to improving the active material utilization and rechargeability for rechargeable Li/S battery. 相似文献
998.
Yadi Liu Shaorong WangJiqin Qian Xianshuang XinZhongliang Zhan Tinglian Wen 《International Journal of Hydrogen Energy》2013
The perovskite structured oxide La0.75Sr0.25Cr0.5−xFexMn0.5O3−δ (LSCFMx, x = 0.05, 0.1, 0.15, 0.2, 0.25) powder is prepared by the liquid phase method, using iron as dopant to replace the chromium. According to XRD patterns, perovskite-like LSCFMx are stable in pure H2, except for LSCFM0.25. Thus the maximum content of Fe doping is 0.2. The calculated lattice volume increases along with the content of iron and the powders show excellent chemical compatibility with yttria-stabilized zirconia (YSZ). The electrical conductivities for LSCFM0.15 and LSCFM0.2 are very comparative, and they exhibit similar performance as catalytic materials. In contrast, the different sintered temperature with the LSCFM0.2 catalytic layer, at 1300 °C exhibits higher electrochemical performance. When dry methane is used as the fuel, the ohmic resistance and polarization resistance are 0.15 and 0.55 Ω cm2, respectively, and the power density reaches 550 mW cm−2. 相似文献
999.
介绍了以聚四氟乙烯废料制备四氟乙烯的工艺路线和设备构成,分析了该工艺的优势及存在的问题,认为利用废料裂解生产四氟乙烯是投资省、成本低、适应性广、资源综合利用的好项目。 相似文献
1000.
Qing Xu Di Zhan Han-Xing Liu Wen Chen Duan-Ping Huang Feng Zhang 《Acta Materialia》2013,61(12):4481-4489
BaZrxTi1?xO3 (x = 0.2, 0.25, 0.3) ceramics were prepared by a citrate method. The ferroelectric phase transition behavior and bias electric-field-induced dielectric nonlinearity of the ceramics were investigated. With increasing zirconium content, the phase transition behavior of the ceramics changed from a diffusion phase transition to relaxor-like behavior. Applying bias electric field in diverse manners led to differing effects on the dielectric nonlinearity, depending on the zirconium content of the ceramics. These dielectric phenomena were related to the polarization response of polar nano-regions (PNRs) embedded in the ceramics, which are macroscopically in the paraelectric state at room temperature. The characteristic parameters of PNRs were determined by fitting the dielectric constants under bias electric field to a multipolarization mechanism model. It was found that the size of PNRs was decreased with increasing zirconium content. The evolution of the phase transition behavior and dielectric nonlinearity with zirconium content was interpreted in relation to the size change of PNRs. 相似文献