全文获取类型
收费全文 | 66818篇 |
免费 | 7089篇 |
国内免费 | 2640篇 |
专业分类
电工技术 | 3017篇 |
综合类 | 4959篇 |
化学工业 | 14911篇 |
金属工艺 | 6657篇 |
机械仪表 | 3214篇 |
建筑科学 | 6410篇 |
矿业工程 | 1319篇 |
能源动力 | 9347篇 |
轻工业 | 4792篇 |
水利工程 | 559篇 |
石油天然气 | 3147篇 |
武器工业 | 885篇 |
无线电 | 2131篇 |
一般工业技术 | 7839篇 |
冶金工业 | 4361篇 |
原子能技术 | 1250篇 |
自动化技术 | 1749篇 |
出版年
2024年 | 291篇 |
2023年 | 1035篇 |
2022年 | 1817篇 |
2021年 | 2138篇 |
2020年 | 2252篇 |
2019年 | 1882篇 |
2018年 | 1706篇 |
2017年 | 2027篇 |
2016年 | 2375篇 |
2015年 | 2280篇 |
2014年 | 3885篇 |
2013年 | 4016篇 |
2012年 | 4548篇 |
2011年 | 4777篇 |
2010年 | 3589篇 |
2009年 | 3706篇 |
2008年 | 2945篇 |
2007年 | 4155篇 |
2006年 | 3892篇 |
2005年 | 3431篇 |
2004年 | 3080篇 |
2003年 | 2693篇 |
2002年 | 2522篇 |
2001年 | 2059篇 |
2000年 | 1737篇 |
1999年 | 1396篇 |
1998年 | 1094篇 |
1997年 | 977篇 |
1996年 | 772篇 |
1995年 | 654篇 |
1994年 | 567篇 |
1993年 | 433篇 |
1992年 | 395篇 |
1991年 | 261篇 |
1990年 | 212篇 |
1989年 | 203篇 |
1988年 | 136篇 |
1987年 | 104篇 |
1986年 | 79篇 |
1985年 | 67篇 |
1984年 | 88篇 |
1983年 | 65篇 |
1982年 | 69篇 |
1981年 | 20篇 |
1980年 | 19篇 |
1979年 | 14篇 |
1977年 | 7篇 |
1975年 | 5篇 |
1959年 | 28篇 |
1951年 | 23篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Zenan Yu Julian Moore Jean Calderon Lei Zhai Jayan Thomas 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(39):5289-5295
Cable‐shaped supercapacitors (SCs) have recently aroused significant attention due to their attractive properties such as small size, lightweight, and bendability. Current cable‐shaped SCs have symmetric device configuration. However, if an asymmetric design is used in cable‐shaped supercapacitors, they would become more attractive due to broader cell operation voltages, which results in higher energy densities. Here, a novel coil‐type asymmetric supercapacitor electrical cable (CASEC) is reported with enhanced cell operation voltage and extraordinary mechanical‐electrochemical stability. The CASECs show excellent charge–discharge profiles, extraordinary rate capability (95.4%), high energy density (0.85 mWh cm−3), remarkable flexibility and bendability, and superior bending cycle stability (≈93.0% after 4000 cycles at different bending states). In addition, the CASECs not only exhibit the capability to store energy but also to transmit electricity simultaneously and independently. The integrated electrical conduction and storage capability of CASECS offer many potential applications in solar energy storage and electronic gadgets. 相似文献
2.
M. R. Thompson 《Drug development and industrial pharmacy》2015,41(8):1223-1231
Twin screw granulation (TSG) is a new process of interest to the pharmaceutical community that can continuously wet granulate powders, doing so at lower liquid concentrations and with better product consistency than found by a high shear batch mixer. A considerable body of research has evolved over the short time since this process was introduced but generally with little comparison of results. A certain degree of confidence has been developed through these studies related to how process variables and many attributes of machinery configuration will affect granulation but some major challenges still lay ahead related to scalability, variations in the processing regimes related to degree of channel fill and the impact of wetting and granulation of complex powder formulations. This review examines the current literature for wet granulation processes studied in twin screw extrusion machinery, summarizing the influences of operational and system parameters affecting granule properties as well as strives to provide some practical observations to newly interested users of the technique. 相似文献
3.
Load testing of applications is an important and costly activity for software provider companies. Classical solutions are very difficult to set up statically, and their cost is prohibitive in terms of both human and hardware resources. Virtualized cloud computing platforms provide new opportunities for stressing an application's scalability, by providing a large range of flexible and less expensive (pay‐per‐use model) computation units. On the basis of these advantages, load testing solutions could be provided on demand in the cloud. This paper describes a Benchmark‐as‐a‐Service solution that automatically scales the load injection platform and facilitates its setup according to load profiles. Our approach is based on: (i) virtualization of the benchmarking platform to create self‐scaling injectors; (ii) online calibration to characterize the injector's capacity and impact on the benched application; and (iii) a provisioning solution to appropriately scale the load injection platform ahead of time. We also report experiments on a benchmark illustrating the benefits of this system in terms of cost and resource reductions. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
4.
5.
6.
7.
美国固体照明技术进展概况 总被引:2,自引:0,他引:2
介绍了美国能源部于2002年开始实施的固体照明(SSL)技术的"下一代照明计划".同时对美国SSL技术的研发、生产和使用现状以及召开学术会议的情况做了叙述. 相似文献
8.
600 A IGBT开关电路及其散热系统设计 总被引:1,自引:0,他引:1
采用IGBT开关电路,对大功率电阻带进行直流脉宽调制控制,实现了内燃机车大功率直流发电机负载实验中的负载大小的连续调节。为了避免在实验过程中IGBT器件的温度过高,采用独特的双管IGBT结构和双向强迫风冷的散热系统。实验表明该电路运行稳定、可靠。 相似文献
9.
实体造型中的几何约束 总被引:5,自引:0,他引:5
实体造型是一个基于约束的过程,完成从功能约束到几何约束、再到代数约束的转化而得到实体模型。本文讨论了几何约束的层次性及其表示,并且对几何约束同设计意图的关系进行了研究,提出了基于CSG/GCG/B-rep的模型表示。 相似文献
10.
This paper presents a model of heterogenous diffusion in capillary porous materials during the process of drying. The governing heat and mass transfer equations have been established using the liquid as well as vapor flow. Two models have been presented. Model 1 does not consider the heat conduction while the model 2 has been established by considering the conduction. The developed models and the numerical solutions of the resulting differential equations can take into account the moisture and temperature dependent thermophysical properties of the product. All equations have been established in spherical coordinates but the programme written for the purpose of calculations can be used for other geometries also. Numerical calculations have been performed for gas concrete and tiles using model 1, while model 2 has been used for gas concrete only because of the lack of data for thermophysical properties of the tile. For gas concrete it was seen that conduction has only marginal effect on the drying process and the numerical predictions of the drying process were reasonably accurate. 相似文献