全文获取类型
收费全文 | 24540篇 |
免费 | 2570篇 |
国内免费 | 1439篇 |
专业分类
电工技术 | 1785篇 |
综合类 | 2030篇 |
化学工业 | 3465篇 |
金属工艺 | 1195篇 |
机械仪表 | 1355篇 |
建筑科学 | 1746篇 |
矿业工程 | 571篇 |
能源动力 | 527篇 |
轻工业 | 3492篇 |
水利工程 | 717篇 |
石油天然气 | 706篇 |
武器工业 | 188篇 |
无线电 | 2725篇 |
一般工业技术 | 2575篇 |
冶金工业 | 980篇 |
原子能技术 | 334篇 |
自动化技术 | 4158篇 |
出版年
2024年 | 158篇 |
2023年 | 484篇 |
2022年 | 1001篇 |
2021年 | 1199篇 |
2020年 | 937篇 |
2019年 | 797篇 |
2018年 | 799篇 |
2017年 | 988篇 |
2016年 | 854篇 |
2015年 | 1263篇 |
2014年 | 1515篇 |
2013年 | 1933篇 |
2012年 | 1965篇 |
2011年 | 2073篇 |
2010年 | 1808篇 |
2009年 | 1674篇 |
2008年 | 1644篇 |
2007年 | 1501篇 |
2006年 | 1332篇 |
2005年 | 1057篇 |
2004年 | 751篇 |
2003年 | 478篇 |
2002年 | 395篇 |
2001年 | 371篇 |
2000年 | 293篇 |
1999年 | 208篇 |
1998年 | 132篇 |
1997年 | 101篇 |
1996年 | 89篇 |
1995年 | 71篇 |
1994年 | 55篇 |
1993年 | 55篇 |
1992年 | 56篇 |
1991年 | 30篇 |
1990年 | 38篇 |
1989年 | 31篇 |
1988年 | 28篇 |
1987年 | 31篇 |
1986年 | 38篇 |
1985年 | 25篇 |
1984年 | 35篇 |
1983年 | 25篇 |
1982年 | 23篇 |
1981年 | 22篇 |
1980年 | 28篇 |
1979年 | 21篇 |
1978年 | 19篇 |
1977年 | 23篇 |
1976年 | 11篇 |
1975年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
In this paper, we discuss the critical issues with the implementation of electronic medical records and argue that the emerging e-services will not fully resolve the issues if they do not work together. To meet the challenge, we propose an integrated e-service model consisting of both process- and data-oriented grids that glue together distributed electronic medical services, records, and application services. We also provide an implementation architecture and prototype that validates the model. 相似文献
92.
Robert Van Dam Irene Langkilde-Geary Dan Ventura 《Knowledge and Information Systems》2013,35(3):525-552
The ADtree, a data structure useful for caching sufficient statistics, has been successfully adapted to grow lazily when memory is limited and to update sequentially with an incrementally updated dataset. However, even these modified forms of the ADtree still exhibit inefficiencies in terms of both space usage and query time, particularly on datasets with very high dimensionality and with high-arity features. We propose four modifications to the ADtree, each of which can be used to improve size and query time under specific types of datasets and features. These modifications also provide an increased ability to precisely control how an ADtree is built and to tune its size given external memory or speed requirements. 相似文献
93.
94.
Donglai Lu Jun Wang Limin Wang Dan Du Charles Timchalk Richard Barry Yuehe Lin 《Advanced functional materials》2011,21(22):4371-4378
A novel disposable electrochemical immunosensor for highly selective and sensitive detection of organophosphorylated butyrylcholinesterase (OP‐BChE), a specific biomarker for exposure to toxic organophosphorus agents, is presented. In this new approach, zirconia nanoparticles (ZrO2) were employed to selectively capture the OP moiety of OP‐BChE adducts, followed by quantum dot (QD)‐tagged anti‐BChE antibodies for amplified quantification. The captured CdSe‐QD tags can be sensitively detected by stripping voltammetry using an in situ bismuth‐plating method. The OP agent, diisopropylfluorophosphate (DFP), was selected to prepare OP‐BChE adducts in various matrices. The formation of OP‐BChE adducts in plasma sample was confirmed using mass spectroscopy. The developed electrochemical immunosensor demonstrates a highly linear voltammetric response over the range of 0.1 to 30 nM OP‐BChE, with a detection limit of 0.03 nM (based on signal/noise = 3), coupled with a good reproducibility (relative standard deviation 4.5%). Moreover, the immunosensor has been validated with biomonitoring of OP‐BChE adducts in the plasma samples. This novel nanoparticle‐based electrochemical immunosensor thus provides an alternative way for designing a sensitive and cost‐effective sensing platform for on‐site screening/evaluating exposure to a variety of OP agents. 相似文献
95.
Purification of cadmium by selective volatilization in vacuum in presence of oxide phase on its melt
Purification of cadmium in the presence of a thin (~0·001?mm) oxide layer on the surface of the molten metal was carried out using a simple system designed and fabricated locally. The analytical results revealed that the distillation through oxide layer gave better separation for Co, Ni, Cu, Zn, Ag, Sn, Hg and Tl, when compared to the distillation without oxide layer. This was attributed due to the impurity metal oxide phases formation on the surface of the molten metal. The influence of oxygen flow time on the distillation rate of cadmium was established. There was no excess oxygen (O) retained in the distillate after two consecutive vacuum distillations through oxide route. The experiments were conducted at the level of nearly 1·5?kg a batch to study the impurities behaviour due to upscaling. The detailed chemical analysis of 58 impurity elements in Cd in presence and absence of oxide layer was carried out by glow discharge mass spectrometry (GDMS). 相似文献
96.
97.
Stress corrosion crack growth rates of 304L stainless steel after one-directionally warm-rolled along the longitudinal (L) direction were measured in oxygenated and deoxygenated pure water at 288 °C. The fracture mode is mainly intergranular in the Transverse-longitudinal (T-L) orientation specimen, while it is occasionally intergranular in the Longitudinal-transverse (L-T) orientation specimen. The crack growth rates in the T-L orientation are higher than those in the L-T orientation in both oxygenated and deoxygenated environments, which is related to the effective cracking growth path as the result of microstructural anisotropy and applied loading direction. 相似文献
98.
99.
SHU XiaYun ZHANG HongHai LIU HuaYong XIE Dan & XIAO JunFeng School of Mechanical Science Engineering Huazhong University of Science Technology Wuhan China Division of MOEMS Wuhan National Laboratory of Optoelectronics 《中国科学:信息科学(英文版)》2010,(1)
Fluid dispensing is a method by which fluid materials(such as epoxy,adhesive,and encapsulant) are delivered in a controlled manner in electronics packaging.Fluid jetting,derived from inkjet technology,is a noncontact,data-driven fluid dispensing technology.But ideal fluid materials for packaging are usually high viscous,which is difficult to realize by traditional inkjet technology.In this paper,a mechanical micro-droplet jetting system for high viscosity fluid was proposed.It consists of dispensing valve,m... 相似文献
100.