全文获取类型
收费全文 | 36825篇 |
免费 | 3849篇 |
国内免费 | 1849篇 |
专业分类
电工技术 | 932篇 |
综合类 | 1945篇 |
化学工业 | 6443篇 |
金属工艺 | 9365篇 |
机械仪表 | 2123篇 |
建筑科学 | 1021篇 |
矿业工程 | 1178篇 |
能源动力 | 1434篇 |
轻工业 | 1159篇 |
水利工程 | 286篇 |
石油天然气 | 765篇 |
武器工业 | 265篇 |
无线电 | 2608篇 |
一般工业技术 | 8183篇 |
冶金工业 | 3627篇 |
原子能技术 | 418篇 |
自动化技术 | 771篇 |
出版年
2024年 | 170篇 |
2023年 | 1036篇 |
2022年 | 960篇 |
2021年 | 1422篇 |
2020年 | 1506篇 |
2019年 | 1456篇 |
2018年 | 1183篇 |
2017年 | 1351篇 |
2016年 | 1202篇 |
2015年 | 1216篇 |
2014年 | 1804篇 |
2013年 | 2346篇 |
2012年 | 2090篇 |
2011年 | 2578篇 |
2010年 | 1728篇 |
2009年 | 1943篇 |
2008年 | 1779篇 |
2007年 | 2120篇 |
2006年 | 2104篇 |
2005年 | 1868篇 |
2004年 | 1580篇 |
2003年 | 1566篇 |
2002年 | 1221篇 |
2001年 | 1003篇 |
2000年 | 959篇 |
1999年 | 757篇 |
1998年 | 630篇 |
1997年 | 541篇 |
1996年 | 442篇 |
1995年 | 371篇 |
1994年 | 316篇 |
1993年 | 241篇 |
1992年 | 204篇 |
1991年 | 154篇 |
1990年 | 134篇 |
1989年 | 117篇 |
1988年 | 68篇 |
1987年 | 55篇 |
1986年 | 53篇 |
1985年 | 38篇 |
1984年 | 40篇 |
1983年 | 36篇 |
1982年 | 36篇 |
1981年 | 19篇 |
1980年 | 17篇 |
1979年 | 11篇 |
1978年 | 15篇 |
1977年 | 9篇 |
1976年 | 7篇 |
1975年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Martensitic stabilization caused by deformation in a TiNi shape memory alloy was studied.Special attention was paid to the deformed microstructures to identify the cause of martensitic stabilization.Martensitic stabilization was demonstrated by differential scanning calorimetry for the tensioned TiNi shape memory alloy.Transmission electron microscopy revealed that antiphase boundaries were formed because of the fourfold dissociation of[110]B19'super lattice dislocations and were preserved after reverse transformation due to the lattice correspondence.Martensitic stabilization was attributed to dislocations induced by deformation,which reduced the ordering degree of the microstructure,spoiled the reverse path from martensite to parent phase compared with thermoelastic transformation,and imposed resistance on phase transformation through the stress field. 相似文献
102.
103.
生物医用钛合金具有高强度、良好的耐蚀性能、较低的弹性模量、优异的生物相容性,已成为具有广阔应用前景的医用金属材料之一.与传统医用钛合金相比,超细晶医用钛合金具有更高的强度与更好的疲劳性能以及耐腐蚀性能.此外,超细晶钛合金可诱导骨组织向内生长,增加界面结合强度,加快骨修复进程,在硬组织修复材料领域具有广阔的应用前景.阐述了各种大塑性变形(Severe Plastic Deformation)法制备超细晶生物医用钛合金的研究状况与最新进展,指出了SPD法制备医用钛合金中存在的技术问题和发展方向,并展望了利用SPD法对生物医用钛合金改性将成为生物医用材料的研究热点. 相似文献
104.
105.
Nanocrystalline solid solution CeO2-Nd2O3 powders were prepared by low temperature combustion process.Special attention was paid to the influence of the glycine/metal ratio and calcination temperature on the powders phase structure, morphology and particle size.TG-DSC curves and XRD peaks of different glycine/metal ratio show that smaller particle size can be obtained with a slightly fuel-deficient ratio.XRD results indicate that the as-prepared powders are crystallized in a single fluorite structure.The crystalline size ranges from 9 to 24 nm, which increases with the increase of calcination temperature.The lower SEM images were characterized by the spongy and form-like microstructure of the powders.Organic agent may be gradually eliminated by high temperature calcination process. 相似文献
106.
王苏华 《西华大学学报(自然科学版)》1996,(2)
探讨了ZLN205A高强度铝铜合金的铸造性能和热处理工艺方法,阐述了ZL205A铝铜合金在T5热处理时,如何才能达到机械性能的工艺方法。 相似文献
107.
Zhonghao XIE 《等离子体科学和技术》2020,22(8):85503
Tegillarca granosa (T. granosa) is susceptible to heavy metals, which may pose a threat to
consumer health. Thus, healthy and polluted T. granosa should be distinguished quickly. This
study aimed to rapidly identify heavy metal pollution by using laser-induced breakdown
spectroscopy (LIBS) coupled with linear regression classification (LRC). Five types of T.
granosa were studied, namely, Cd-, Zn-, Pb-contaminated, mixed contaminated, and control
samples. Threshold method was applied to extract the significant variables from LIBS spectra.
Then, LRC was used to classify the different types of T. granosa. Other classification models
and feature selection methods were used for comparison. LRC was the best model, achieving an
accuracy of 90.67%. Results indicated that LIBS combined with LRC is effective and feasible
for T. granosa heavy metal detection. 相似文献
108.
《等离子体科学和技术》2020,22(7):74010
Accurate measurement of trace heavy metal mercury(Hg) in flue gas of coal-fired units is great significance for ecological and environmental protection.Mixed gas was used to simulate the actual flue gas of a power plant in this study.A laser-induced breakdown spectroscopy(LIBS)system for Hg measurement in mixed gas was built to study the effect of mixed gas pressure,Hg concentration in mixed gas and delay time on Hg measurement.The experimental results show that the appropriate low mixed gas pressure can obtain high Hg signal intensity and signal to noise ratio.The Hg signal intensity and signal to noise ratio increased with the increase of Hg concentration in mixed gas.The Hg signal intensity and signal to noise ratio decreased with the increase in delay time.According to the above results,the optimized measurement conditions can be determined.Different Hg concentrations in mixed gas were quantitatively analyzed by the internal standard method and traditional calibration method respectively.The relative error of prediction of the test sample obtained by the internal standard method was within 11.11%.The relative error of prediction of the traditional calibration method was less than 14.54%.This proved that the internal standard method can improve the accuracy of quantitative analysis of Hg concentration in flue gas using LIBS. 相似文献
109.
Christian Friebe Martin D. Hager Andreas Winter Ulrich S. Schubert 《Advanced materials (Deerfield Beach, Fla.)》2012,24(3):332-345
Electropolymerization represents a suitable and well‐established approach for the assembly of polymer structures, in particular with regard to the formation of thin, insoluble films. Utilization of monomers that are functionalized with metal complex units allows the combination of structural and functional benefits of polymers and metal moieties. Since a broad range of both electropolymerizable monomers and metal complexes are available, various structures and, thus, applications are possible. Recent developments in the field of synthesis and potential applications of metal‐functionalized polymers obtained via electropolymerization are presented, highlighting the significant advances in this field of research. 相似文献
110.
Lithium Intercalation Compound Dramatically Influences the Electrochemical Properties of Exfoliated MoS2 下载免费PDF全文
Adriano Ambrosi Zdeněk Sofer Martin Pumera 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(5):605-612
MoS2 and other transition metal dichalcogenides (TMDs) have recently gained a renewed interest due to the interesting electronic, catalytic, and mechanical properties which they possess when down‐sized to single or few layer sheets. Exfoliation of the bulk multilayer structure can be achieved by a preliminary chemical Li intercalation followed by the exfoliation due to the reaction of Li with water. Organolithium compounds are generally adopted for the Li intercalation with n‐butyllithium (n‐Bu‐Li) being the most common. Here, the use of three different organolithium compounds are investigated and compared, i.e., methyllithium (Me‐Li), n‐butyllithium (n‐Bu‐Li) and tert‐butyllithium (t‐Bu‐Li), used for the exfoliation of bulk MoS2. Scanning transmission electron microscopy (STEM), Raman spectroscopy, X‐ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV) are adopted for a comprehensive characterization of all materials under investigation. In addition, catalytic properties towards the hydrogen evolution reaction (HER) and capacitive properties are also tested. Different organolithium compounds exhibit different extent of Li intercalation resulting in different degrees of exfoliation. The inherent electrochemical behavior of MoS2 consisting of significant anodic and cathodic peaks as well as its capacitive behavior and catalytic properties towards hydrogen evolution reaction are strongly connected to the exfoliation compound used. This research significantly contributes to the development of large‐scale synthesis of electrocatalytic MoS2‐based materials. 相似文献