全文获取类型
收费全文 | 9911篇 |
免费 | 831篇 |
国内免费 | 349篇 |
专业分类
电工技术 | 558篇 |
综合类 | 497篇 |
化学工业 | 1486篇 |
金属工艺 | 413篇 |
机械仪表 | 461篇 |
建筑科学 | 538篇 |
矿业工程 | 186篇 |
能源动力 | 338篇 |
轻工业 | 794篇 |
水利工程 | 143篇 |
石油天然气 | 364篇 |
武器工业 | 64篇 |
无线电 | 1077篇 |
一般工业技术 | 1240篇 |
冶金工业 | 1764篇 |
原子能技术 | 112篇 |
自动化技术 | 1056篇 |
出版年
2024年 | 21篇 |
2023年 | 108篇 |
2022年 | 230篇 |
2021年 | 322篇 |
2020年 | 257篇 |
2019年 | 256篇 |
2018年 | 246篇 |
2017年 | 274篇 |
2016年 | 300篇 |
2015年 | 312篇 |
2014年 | 495篇 |
2013年 | 553篇 |
2012年 | 573篇 |
2011年 | 667篇 |
2010年 | 596篇 |
2009年 | 508篇 |
2008年 | 505篇 |
2007年 | 465篇 |
2006年 | 393篇 |
2005年 | 408篇 |
2004年 | 270篇 |
2003年 | 275篇 |
2002年 | 287篇 |
2001年 | 273篇 |
2000年 | 190篇 |
1999年 | 203篇 |
1998年 | 564篇 |
1997年 | 342篇 |
1996年 | 233篇 |
1995年 | 176篇 |
1994年 | 129篇 |
1993年 | 129篇 |
1992年 | 56篇 |
1991年 | 47篇 |
1990年 | 49篇 |
1989年 | 45篇 |
1988年 | 32篇 |
1987年 | 31篇 |
1986年 | 16篇 |
1985年 | 17篇 |
1984年 | 11篇 |
1983年 | 12篇 |
1982年 | 11篇 |
1981年 | 17篇 |
1980年 | 21篇 |
1978年 | 7篇 |
1977年 | 28篇 |
1976年 | 108篇 |
1975年 | 6篇 |
1955年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Senior nursing students described their interactions with faculty in a journal writing assignment. These interactions were categorized by the ethical perspectives of justice, autonomy, beneficence, and caring. An ethical analysis of faculty-student interactions is a strategy that may help nursing faculty and students understand differing perceptions about their relationships. 相似文献
32.
BACKGROUND: We have previously observed a potentiation of the metabolic response to cachectin/tumor necrosis factor (TNF) by total parenteral nutrition (TPN) but not in anorexic orally fed animals. We hypothesized that nutritional status might affect TNF clearance kinetics. METHODS: We compared the clearance of a bolus of labeled TNF in TPN-fed animals given sufficient nutrients to grow called weight-gaining rats (WGR) with those given 50% of the WGR called weight-losing rats (WLR) and with orally fed rats (OFR). Data were analyzed using a two-compartment open system model and by linear systems analysis. RESULTS: The data from both types of analysis indicator that although metabolic clearance was similar, WGR had a slower fractional TNF clearance rate (FCR) as well as a larger volume of distribution than WLR or OFR. Further analysis showed that an increased proportion of the total mass of TNF resided in a plasma-associated compartment in WGR compared with WLR and OFR. In addition, WGR had reduced uptake of labeled TNF by the kidney. CONCLUSION: The data suggest that nutrition support influences either the distribution of TNF or the FCR, resulting in a greater retention in the plasma-associated compartment with intact absolute removal rates. This study has important implications concerning the type of nutrition support provided to the critically ill patient because our data suggest that clinical states with increased circulating TNF levels may be adversely affected by currently available nutritional practices. 相似文献
33.
34.
35.
The notion of pseudorandomness is the theoretical foundation on which to consider the soundness of a basic structure used in some block ciphers. We examine the pseudorandomness of the block cipher KASUMI, which will be used in the next‐generation cellular phones. First, we prove that the four‐round unbalanced MISTY‐type transformation is pseudorandom in order to illustrate the pseudorandomness of the inside round function FI of KASUMI under an adaptive distinguisher model. Second, we show that the three‐round KASUMI‐like structure is not pseudorandom but the four‐round KASUMI‐like structure is pseudorandom under a non‐adaptive distinguisher model. 相似文献
36.
JaeHyunKim JounHoLee JiChulLim ChangHoonLee MooHyoungSong JuYeonYoon HeeDongChoi JeomJaeKim ChangHoOh SangDeogYeo 李路海 《现代显示》2004,31(5):31-33
薄膜晶体管液晶电视(TFT-LCD TV)因为具有薄、轻、紧凑和可随意放置的特点,已经占据了大部分电视机市场。除了这些物理特性以外,最重要的特性是已具有了良好像质的对比度。为了将对比度提高到1:600以上,对偏振片膜、背光源板、滤色片树脂、电极锥角和摩擦条件等都进行了研究。优化的背光板组合,光滑的电极锥角和摩擦方法的控制是提高对比度的主要控制因素。应用新开发的滤色片树脂,对获得高对比度最为有效。 相似文献
37.
With video compression standards such as MPEG‐4, a transmission error happens in a video‐packet basis, rather than in a macroblock basis. In this context, we propose a semantic error prioritization method that determines the size of a video packet based on the importance of its contents. A video packet length is made to be short for an important area such as a facial area in order to reduce the possibility of error accumulation. To facilitate the semantic error prioritization, an efficient hardware algorithm for face tracking is proposed. The increase of hardware complexity is minimal because a motion estimation engine is efficiently re‐used for face tracking. Experimental results demonstrate that the facial area is well protected with the proposed scheme. 相似文献
38.
疏水缔合型聚丙烯酰胺的合成与性能评价 总被引:1,自引:0,他引:1
为了提高高相对分子质量的聚丙烯酰胺的抗温抗盐性能,利用自制的两亲表面活性单体与丙烯酰胺共聚合成了疏水缔合型聚丙烯酰胺并进行室内评价。结果表明,在高温、高盐、高钙条件下,合成的疏水缔合型聚丙烯酰胺具有良好的增粘性和较强的热稳定性;克服了疏水缔合型聚合物在盐水中溶解性差的问题,可用各种矿化度的盐水和油田产出污水配制;具有良好的无机盐增粘性能和抗温性能。 相似文献
39.
后浇带质量控制的措施 总被引:1,自引:0,他引:1
后浇带起着超长建筑的温度伸缩、高层建筑高层部分与裙房间沉降缝的作用,已普遍采用,但有些工程由于施工不当,设了后浇带起不到应有作用,本文就施工中如何采取有效措施,对后浇带的质量进行控制,作了探讨,以期能真正发挥后浇带的作用。 相似文献
40.