全文获取类型
收费全文 | 43682篇 |
免费 | 4364篇 |
国内免费 | 2382篇 |
专业分类
电工技术 | 1373篇 |
综合类 | 3342篇 |
化学工业 | 12453篇 |
金属工艺 | 4953篇 |
机械仪表 | 1846篇 |
建筑科学 | 5341篇 |
矿业工程 | 835篇 |
能源动力 | 1648篇 |
轻工业 | 1931篇 |
水利工程 | 436篇 |
石油天然气 | 1228篇 |
武器工业 | 629篇 |
无线电 | 1726篇 |
一般工业技术 | 10339篇 |
冶金工业 | 1306篇 |
原子能技术 | 130篇 |
自动化技术 | 912篇 |
出版年
2024年 | 230篇 |
2023年 | 603篇 |
2022年 | 1089篇 |
2021年 | 1377篇 |
2020年 | 1452篇 |
2019年 | 1235篇 |
2018年 | 1180篇 |
2017年 | 1656篇 |
2016年 | 1693篇 |
2015年 | 1739篇 |
2014年 | 2365篇 |
2013年 | 2451篇 |
2012年 | 2873篇 |
2011年 | 3199篇 |
2010年 | 2537篇 |
2009年 | 2692篇 |
2008年 | 2185篇 |
2007年 | 2969篇 |
2006年 | 2763篇 |
2005年 | 2256篇 |
2004年 | 1846篇 |
2003年 | 1682篇 |
2002年 | 1444篇 |
2001年 | 1254篇 |
2000年 | 1098篇 |
1999年 | 893篇 |
1998年 | 723篇 |
1997年 | 630篇 |
1996年 | 532篇 |
1995年 | 429篇 |
1994年 | 363篇 |
1993年 | 305篇 |
1992年 | 193篇 |
1991年 | 145篇 |
1990年 | 84篇 |
1989年 | 55篇 |
1988年 | 52篇 |
1987年 | 34篇 |
1986年 | 7篇 |
1985年 | 19篇 |
1984年 | 21篇 |
1983年 | 19篇 |
1982年 | 22篇 |
1980年 | 17篇 |
1979年 | 8篇 |
1977年 | 1篇 |
1967年 | 1篇 |
1957年 | 1篇 |
1956年 | 1篇 |
1951年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
PENGLiming MAOXiemin XUKuangdi DINGWenjiang 《稀有金属(英文版)》2002,21(1):62-66
In order to develop a new type of contact cable with high strength and high electrical conductivity, Cu-Cr alloy series were selected as materials and Cu-Cr alloy castings were produced by means of directional solidification continuous casting (DSCC) process. The results show that the fibrillar strengthening phase, 13-Cr, orderly arranges among the copper matrix phase along the wire direction; and a microstructure of in-situ composite forms, which retains the basic property of good conductivity of the copper matrix and meanwhile obtains the strengthening effect of [3-Cr phase. The production technology as well as the mechanical property, electrical property, and synthetic property of the in-situ composite contact cables was discussed. 相似文献
73.
本文研究了用冠醚树脂二苯并-18-冠-6甲醛聚合物(简称PDB-18C6)对T1(Ⅰ),Au(Ⅲ),Cu(Ⅱ)的吸附行为。实验表明,在盐酸溶液中冠醚树脂的吸附效率顺序为Au(Ⅲ)>T1(Ⅰ)>Cu(Ⅱ)。用高氯酸和乙二醇乙醚淋洗T1(Ⅰ),Au(Ⅲ),它们的回收率一般在82-98.9%和98-100%。还在1.2m回旋加速器的外靶装置上,用25-27MeV的α粒子轰击金靶,累计束流强度为27μA·h,经处理分离后得到仅含0.50%~(200)T1的较高纯度的~(199)T1。 相似文献
74.
On the basis of generalization of the results of investigation of the operation of rodlike elements of composite materials, we make a conclusion that the influence of various factors on the deformability of these elements is studied incompletely. The comparison of the stress-strain states for different models of concrete and reinforced-concrete elements makes it possible to describe the effect of longitudinal reinforcement (coefficient of reinforcement, strength and deformation characteristics) on the critical level of strains in the cross section. According to the results of our investigations, we give recommendations concerning the evaluation of the critical value of the coefficient of reinforcement above which one may observe the effect of reinforcement on the deformability of the analyzed sections. It is shown that the compression strength of the brittle base of the composite with inhomogeneous structure decreases as a result of the fracture processes. It is also demonstrated that the existing procedure used for the evaluation of the indicated decrease in strength requires significant improvement. The problem of evaluation of the ultimate value of the coefficient of reinforcement is also analyzed. 相似文献
75.
本文采用粉末冶金法制备了不同成分的PSZ/Mo复合材料。并对其密度、弹性模量和热膨胀系数进行了测量和分析 ,用XRD进行了物相分析。实验结果表明 :纳米氧化锆的烧结性能比金属钼好 ;弹性模量估算选用简单混合法则进行计算时应进行修正 ;钼和氧化锆在烧结时不发生化学反应。通过热压PSZ/Mo功能梯度材料的断口扫描分析发现 :虽然金属钼和纳米氧化锆具有一定增韧作用 ,但材料断裂方式仍以脆性断裂为主 相似文献
76.
王芬 《武汉理工大学学报(材料科学英文版)》2005,20(Z1)
1Introduction Harmfulbacteriaexistanywhereintheworldsuchas soil,air,water,surfacesofobjectsandourskins,etc.Thenumberofbacteriumisenormous,withmanydiffer entspecies.Theyhavethreatenedthehealthofhuman beingsseriously.Withthedevelopmentofeconomyand environme… 相似文献
77.
A Oyane M Kasahara N Ichinose Y Yokoyama M Uchida A Ito 《武汉理工大学学报(材料科学英文版)》2005,20(B12):220-222
A synthetic polymer with a laminin-apatite composite layer on its surface would be useful as a percutaneous device. The preparation of such a composite was attempted in the present study using poly( ethylene terephthalate ) (PET) and polyethylene (PE) as the synthetic polymer. PET and PE plates and those pretreated with an oxygen plasma were alternately dipped in calcium and phosphate ion solutions, and then immersed in a metastable calcium phosphate solution supplemented with laminin ( LCP solution ). The PET and PE plates pretreated with an oxygen plasma formed a uniform and continuous layer of a laminin-apatite composite on their surfaces. In contrast, the PET and PE plates that had not been pretreated with an oxygen plasma did not form a continuous layer of a laminin-apatite composite on their surfaces. The hydrophilic functional groups on the PET and PE surfaces introduced by the plasma treatment were responsible for the successful laminin-apatite coruposite coating. 相似文献
78.
79.
The bonding of β'-Al2O3 and pyrex glass to Al matrix composites by anodic bonding process is achieved. The microstructure of the bonded interface and the joining mechanisms are analyzed with scanning electron microscope (SEM), energy dispersive X-ray fluorescence spectrometer (EDX). It is observed that the bonding region across the interface consists of the metal layer, oxide transitional layer and the ceramic layer, with the transitional layer composed of surface region and sub-surface region. The bonding process can mainly be categorized into anodic bonding process and solid state diffusing process. The pile-up of the ions and its drift in the interface area are the main reasons for anode oxidation and joining of the interface. The temperature, voltage and the drift ions in the ceramic or glass during the bonding process are the essential conditions to solid state diffusing and oxide bonding at the interface. The voltages, temperature, pressure as well as the surface state are the main factors that influence the anodic bonding. 相似文献
80.
In order to improve the physical properties and slag corrosion resistance of refractory materials for hot metal pretreatment, different contents of composite metal powders (CMP) were introduced into Al2O3-SiC-C refractory castables. The effect of CMP on the microstructure, physical properties and slag corrosion resistance of Al2O3-SiC-C refractory castables were studied. The results show that the multi scale reinforcing phases including flake crystals, rod shaped fibers, filamentous fibers and whiskers are in situ formed in the samples with addition of CMP, which result to the improvement of the cold modulus of rupture and cold crushing strength. When the addition of CMP is 6 wt.%, the high temperature modulus of rupture increases by 231%, the thermal shock resistance increases by 77% after thermal shock by water cooling 5 times and the percentage of the slag resistant area reduces by 37.2%. 相似文献