全文获取类型
收费全文 | 25738篇 |
免费 | 2340篇 |
国内免费 | 1605篇 |
专业分类
电工技术 | 765篇 |
技术理论 | 1篇 |
综合类 | 3181篇 |
化学工业 | 7803篇 |
金属工艺 | 2379篇 |
机械仪表 | 852篇 |
建筑科学 | 1372篇 |
矿业工程 | 819篇 |
能源动力 | 785篇 |
轻工业 | 1598篇 |
水利工程 | 476篇 |
石油天然气 | 1238篇 |
武器工业 | 295篇 |
无线电 | 1055篇 |
一般工业技术 | 3208篇 |
冶金工业 | 1759篇 |
原子能技术 | 331篇 |
自动化技术 | 1766篇 |
出版年
2024年 | 88篇 |
2023年 | 303篇 |
2022年 | 495篇 |
2021年 | 694篇 |
2020年 | 746篇 |
2019年 | 671篇 |
2018年 | 589篇 |
2017年 | 799篇 |
2016年 | 904篇 |
2015年 | 911篇 |
2014年 | 1388篇 |
2013年 | 1634篇 |
2012年 | 1837篇 |
2011年 | 1885篇 |
2010年 | 1369篇 |
2009年 | 1463篇 |
2008年 | 1335篇 |
2007年 | 1592篇 |
2006年 | 1558篇 |
2005年 | 1374篇 |
2004年 | 1192篇 |
2003年 | 1053篇 |
2002年 | 891篇 |
2001年 | 734篇 |
2000年 | 650篇 |
1999年 | 572篇 |
1998年 | 445篇 |
1997年 | 389篇 |
1996年 | 325篇 |
1995年 | 315篇 |
1994年 | 308篇 |
1993年 | 225篇 |
1992年 | 191篇 |
1991年 | 164篇 |
1990年 | 131篇 |
1989年 | 106篇 |
1988年 | 86篇 |
1987年 | 73篇 |
1986年 | 41篇 |
1985年 | 30篇 |
1984年 | 33篇 |
1983年 | 19篇 |
1982年 | 33篇 |
1981年 | 9篇 |
1980年 | 9篇 |
1979年 | 9篇 |
1976年 | 2篇 |
1960年 | 1篇 |
1959年 | 2篇 |
1951年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
引用优化设计中一维搜索和黄金分割法,针对数控加工中非圆曲线的处理,给出实用、简洁和新颖的宏程序实现方法,解决在数控系统中求解方程组的问题,是数控用户快速解决相关应用问题的有效手段。 相似文献
32.
Designing Metallic and Insulating Nanocrystal Heterostructures to Fabricate Highly Sensitive and Solution Processed Strain Gauges for Wearable Sensors 下载免费PDF全文
Woo Seok Lee Seung‐Wook Lee Hyungmok Joh Mingi Seong Haneun Kim Min Su Kang Ki‐Hyun Cho Yun‐Mo Sung Soong Ju Oh 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(47)
All‐solution processed, high‐performance wearable strain sensors are demonstrated using heterostructure nanocrystal (NC) solids. By incorporating insulating artificial atoms of CdSe quantum dot NCs into metallic artificial atoms of Au NC thin film matrix, metal–insulator heterostructures are designed. This hybrid structure results in a shift close to the percolation threshold, modifying the charge transport mechanism and enhancing sensitivity in accordance with the site percolation theory. The number of electrical pathways is also manipulated by creating nanocracks to further increase its sensitivity, inspired from the bond percolation theory. The combination of the two strategies achieves gauge factor up to 5045, the highest sensitivity recorded among NC‐based strain gauges. These strain sensors show high reliability, durability, frequency stability, and negligible hysteresis. The fundamental charge transport behavior of these NC solids is investigated and the combined site and bond percolation theory is developed to illuminate the origin of their enhanced sensitivity. Finally, all NC‐based and solution‐processed strain gauge sensor arrays are fabricated, which effectively measure the motion of each finger joint, the pulse of heart rate, and the movement of vocal cords of human. This work provides a pathway for designing low‐cost and high‐performance electronic skin or wearable devices. 相似文献
33.
在满足机构许用压力角条件下,采用0.618法最优确定盘状摆动凸轮机械的最小基圆半径。 相似文献
34.
Jung Hyeon Bae Gun Hee Kim Woong Hee Jeong Hyun Jae Kim 《Journal of the Society for Information Display》2011,19(5):404-409
Abstract— Non‐volatile memory effects of an all‐solution‐processed oxide thin‐film transistor (TFT) with ZnO nanoparticles (NPs) as the charge‐trapping layer are reported. The device was fabricated by using a soluble MgInZnO active channel on a ZrHfOx gate dielectric. ZnO NPs were used as the charge‐trapping site at the gate‐insulator—channel interface, and Al was used for source and drain electrodes. Transfer characteristics of the device showed a large clockwise hysteresis, which can be used to demonstrate its memory function due to electron trapping in the ZnO NP charge‐trapping layer. This memory effect has the potential to be utilized as a memory application on displays and disposable electronics. 相似文献
35.
In this paper, we consider the following nonlinear fractional three-point boundary value problem
36.
37.
Summary In this paper, we investigate the discretization of an elliptic boundary value problem in 3D by means of the hp-version of the finite element method using a mesh of tetrahedrons. We present several bases based on integrated Jacobi polynomials
in which the element stiffness matrix has nonzero entries, where p denotes the polynomial degree. The proof of the sparsity requires the assistance of computer algebra software. Several numerical
experiments show the efficiency of the proposed bases for higher polynomial degrees p.
相似文献
38.
简介了电炉法CS2 废气吸附的原理及工艺流程 ,开辟了H2 S利用的新途径 ,具有较好的环境效益和经济效益 相似文献
39.
对我公司硝铵装置降膜蒸发工序存在的问题进行分析 ,并通过技术改进 ,使干燥洗涤液全部返回系统 ,造粒塔粘塔问题得到缓解 ,取得可观的经济效益和环保效益 相似文献
40.
《国际计算机数学杂志》2012,89(7):865-870
Necessary and sufficient conditions for the matrix equation X+A T X ?2 A=I to have a real symmetric positive definite solution X are derived. Based on these conditions, some properties of the matrix A as well as relations between the solution X and A are derived. 相似文献