全文获取类型
收费全文 | 248057篇 |
免费 | 13056篇 |
国内免费 | 6505篇 |
专业分类
电工技术 | 9497篇 |
技术理论 | 9篇 |
综合类 | 10906篇 |
化学工业 | 38312篇 |
金属工艺 | 14648篇 |
机械仪表 | 12997篇 |
建筑科学 | 11909篇 |
矿业工程 | 4491篇 |
能源动力 | 4722篇 |
轻工业 | 12816篇 |
水利工程 | 4398篇 |
石油天然气 | 9875篇 |
武器工业 | 1062篇 |
无线电 | 26523篇 |
一般工业技术 | 42553篇 |
冶金工业 | 13655篇 |
原子能技术 | 5064篇 |
自动化技术 | 44181篇 |
出版年
2024年 | 729篇 |
2023年 | 2358篇 |
2022年 | 4651篇 |
2021年 | 6268篇 |
2020年 | 4712篇 |
2019年 | 4034篇 |
2018年 | 19118篇 |
2017年 | 18559篇 |
2016年 | 14800篇 |
2015年 | 6242篇 |
2014年 | 7531篇 |
2013年 | 9090篇 |
2012年 | 12596篇 |
2011年 | 19410篇 |
2010年 | 16779篇 |
2009年 | 13913篇 |
2008年 | 15023篇 |
2007年 | 15514篇 |
2006年 | 7423篇 |
2005年 | 7406篇 |
2004年 | 5871篇 |
2003年 | 5853篇 |
2002年 | 5269篇 |
2001年 | 4413篇 |
2000年 | 3920篇 |
1999年 | 3374篇 |
1998年 | 2672篇 |
1997年 | 2236篇 |
1996年 | 2017篇 |
1995年 | 1740篇 |
1994年 | 1474篇 |
1993年 | 1251篇 |
1992年 | 1227篇 |
1991年 | 1096篇 |
1990年 | 1089篇 |
1989年 | 1009篇 |
1988年 | 905篇 |
1987年 | 841篇 |
1986年 | 763篇 |
1985年 | 715篇 |
1984年 | 701篇 |
1981年 | 668篇 |
1979年 | 736篇 |
1978年 | 777篇 |
1977年 | 739篇 |
1976年 | 755篇 |
1975年 | 713篇 |
1974年 | 719篇 |
1973年 | 723篇 |
1972年 | 705篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
The basic methods of verifying continuous automatic belt weighers are described. A comparative analysis of these methods on the basis of experimental studies is made and ways of implementing the results in industry are recommended. 相似文献
62.
Yu. I. Golovin D. V. Lopatin R. K. Nikolaev A. V. Umrikhin 《Technical Physics Letters》2004,30(5):426-428
The effect of crystal orientation on the photogeneration of free charge carriers was studied for C60 single crystals in a weak magnetic field. The photoconductivity sharply depends on the orientation of magnetic field with
respect to the crystallographic directions, showing a 5–8% increase for seven axes of the C60 crystal. 相似文献
63.
世界经济东移已成共识,20世纪是美国的世纪。21世纪是亚洲世纪。历史告诉我们:20世纪的标志性产业之一无疑是LSI。LSI是电子设备的心脏,正是它领导了电子工业的前进,当然地成了美国的重要战略产业。21世纪是视图时代,新世纪引领电子工业发展的是FPD,它是人与电子设备鲜活的界面,是提高和改善人类生活的重要一环,肯定是新世纪的标志性产业之一。事实证明,它已成为今天亚洲国家或地区的重要战略产业。
针对我国实际,作者2004年便提出了我国电子产业要由大变强,必需LSI与FPD“双业并举,共同发展”,不能再走先LSI后FPD的老路。为此,本刊不断发表文章,大力呼吁,愿智者垂听,愿读者赐教。[编者按] 相似文献
64.
Ferrite particles coated with biocompatible phases can be used for hyperthermia treatment of cancer. We have synthesized substituted
calcium hexaferrite, which is not stable on its own but is stabilized with small substitution of La. Hexaferrite of chemical
composition (CaO)0.75(La203)0.20(Fe2O3)6 was prepared using citrate gel method. Hydroxyapatite was prepared by precipitating it from aqueous solution of Ca(NO3)2 and (NH4)2HPO4 maintaining pH above 11. Four different methods were used for coating of hydroxyapatite on ferrite particles. SEM with EDX
and X-ray diffraction analysis shows clear evidence of coating of hydroxyapatite on ferrite particles. These coated ferrite
particles exhibited coercive field up to 2 kOe, which could be made useful for hysteresis heating in hyperthermia. Studies
by culturing BHK-21 cells and WBC over the samples show evidence of biocompatibility. SEM micrographs and cell counts give
clear indication of cell growth on the surface of the sample. Finally coated ferrite particle was implanted in Kasaulli mouse
to test its biocompatibility. The magnetic properties and biocompatibility studies show that these hydroxyapatite coated ferrites
could be useful for hyperthermia. 相似文献
65.
Mechanical behavior of a two-dimensional elastoplastic solid with rectilinear cracks is investigated. Plastic strip model is used to reduce plasticity problem to the equivalent linear elasticity formulation. Two realizations of the mixed mode plastic strip model are considered: in-line plastic strips as proposed by Becker and Gross [Int. J. Fract. 37 (1988) 163], and inclined plastic strips of Panasyuk and Savruk [Appl. Mech. Rev. 47 (1994) 151]. The effective mechanical response predictions are based on the procedure presented in Kachanov et al., [Appl. Mech. Rev. 47 (1994) 151]. Stress-strain relations are obtained for parallel and randomly oriented non-interacting cracks. Results are compared with known elastic solutions. 相似文献
66.
Xue‐Yong Liu Xiao‐Bin Ding Zhao‐Hui Zheng Yu‐Xing Peng Albert S
C Chan C
W Yip Xin‐Ping Long 《Polymer International》2003,52(2):235-240
Amphiphilic magnetic microspheres ranging in diameter from 5 to 100 µm were prepared by dispersion copolymerization of styrene and poly(ethylene oxide) vinylbenzyl (PEO‐VB) macromonomer (MPEO) in the presence of Fe3O4 magnetic fluid. The effects of various polymerization parameters on the average particle size were systematically investigated. The average particle size was found to increase with increasing styrene concentration and initiator concentration. It also increased with decreasing stabilizer concentration and molecular weight of MPEO. The content of the hydroxyl groups localized in the microspheres ranged from 0.01 to 0.2 mmol g?1. © 2003 Society of Chemical Industry 相似文献
67.
Chloride doped polyaniline conducting polymer films have been prepared in a protic acid medium (HCl) by potentiodynamic method
in an electrochemical cell and studied by cyclic voltammetry and FTIR techniques. The FTIR spectra confirmed Cl- ion doping in the polymers. The polymerization rate was found to increase with increasing concentration of aniline monomer.
But the films obtained at high monomer concentration were rough having a nonuniform flaky polyaniline distribution. Results
showed that the polymerization rate did not increase beyond a critical HCl concentration. Cyclic voltammetry suggested that,
the oxidation-reduction current increased with an increase in scan rate and that the undoped polyaniline films were not hygroscopic
whereas chloride doped polyaniline films were found to be highly hygroscopic. 相似文献
68.
69.
番禺30-1砂岩强水驱气藏储层非均质性研究 总被引:7,自引:5,他引:2
针对垂向非均质性严重且边底水能量强的番禺30-1气田面临的潜在开发问题,通过岩心分析及测井二次解释,对其夹层特征及储层非均质性等进行了研究,划分出19个流动单元并定量描述了各流动单元的特征参数,建立了该气田的精细地质模型。综合评价表明,新建的地质模型具有较高的精度,为该气藏合理开发提供了坚实的地质基础。 相似文献
70.
杨宇 《中国室内装饰装修天地》2006,(7):54-61
华风气象影视大楼总面积4万平方米,根据空间功能不同分为办公大楼和商务写字楼两部分,办公大楼是集演播室、制作机房、办公室为一体的九层综合性建筑。设计师杨宇在刚接触到这个项目的时候,面对的是一个既成事实的建筑。 相似文献