全文获取类型
收费全文 | 7931篇 |
免费 | 1182篇 |
国内免费 | 364篇 |
专业分类
电工技术 | 190篇 |
综合类 | 398篇 |
化学工业 | 2396篇 |
金属工艺 | 404篇 |
机械仪表 | 209篇 |
建筑科学 | 253篇 |
矿业工程 | 143篇 |
能源动力 | 164篇 |
轻工业 | 653篇 |
水利工程 | 51篇 |
石油天然气 | 374篇 |
武器工业 | 63篇 |
无线电 | 501篇 |
一般工业技术 | 564篇 |
冶金工业 | 271篇 |
原子能技术 | 164篇 |
自动化技术 | 2679篇 |
出版年
2024年 | 23篇 |
2023年 | 112篇 |
2022年 | 222篇 |
2021年 | 266篇 |
2020年 | 210篇 |
2019年 | 234篇 |
2018年 | 253篇 |
2017年 | 450篇 |
2016年 | 472篇 |
2015年 | 425篇 |
2014年 | 561篇 |
2013年 | 655篇 |
2012年 | 516篇 |
2011年 | 648篇 |
2010年 | 545篇 |
2009年 | 502篇 |
2008年 | 488篇 |
2007年 | 418篇 |
2006年 | 349篇 |
2005年 | 299篇 |
2004年 | 223篇 |
2003年 | 167篇 |
2002年 | 214篇 |
2001年 | 254篇 |
2000年 | 201篇 |
1999年 | 160篇 |
1998年 | 97篇 |
1997年 | 76篇 |
1996年 | 80篇 |
1995年 | 49篇 |
1994年 | 62篇 |
1993年 | 47篇 |
1992年 | 43篇 |
1991年 | 29篇 |
1990年 | 25篇 |
1989年 | 14篇 |
1988年 | 12篇 |
1987年 | 11篇 |
1986年 | 12篇 |
1985年 | 14篇 |
1984年 | 11篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1973年 | 3篇 |
1968年 | 1篇 |
1964年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有9477条查询结果,搜索用时 15 毫秒
1.
本文对微球聚焦测井仪小极板进行研究,利用有限元法计算了小极板的均质及非均质K值,并与实验结果进行了比较,结果表明理论值怀实验值吻合较好,说明了理论计算的正确性,给出了对应于小极板的泥饼校正图版及屏流比曲线,对小极板的推广应用有实用价值。 相似文献
2.
王小龙 《理化检验(物理分册)》1998,34(9):17-20
通过比较多种材料的光滑薄圆筒和切口薄壁圆筒试样的扭断裂曲线,测向两种试验的断裂韧性KIIC相同,从而间接证实了利用光滑薄壁筒测定延性金属断裂韧性KC方法的正确性。 相似文献
3.
简单介绍了碳氧比测井的原理及通常的数据处理方法。分析了由常规数据处理所得曲线仍然存在的问题及可能的成因 ,并给出了可行的修正办法。讨论了另一种可行的曲线异常数据的检测、剔除方法。实践表明 :文章讨论的两点建议都是可行的 ,并且在提高测量曲线质量的同时也提高了地层含油饱和度的解释精度。 相似文献
4.
通过对国际岩石力学委员会JV 公式的论证 ,指出了该公式不符合数理逻辑。结合工程勘察实践 ,拟建了Ky新公式 ,提高了工程岩体完整程度评价方法的科学性。 相似文献
5.
6.
Poly[2‐methoxy‐5‐(2′‐ethyl‐hexyloxy)‐para‐phenylene vinylene] (MEH‐PPV)/silica nanoparticle hybrid films were prepared and characterised. Three kinds of materials were compared: parent MEH‐PPV, MEH‐PPV/silica (hybrid A films), and MEH‐PPV/coupling agent MSMA/silica (hybrid B films), in which MSMA is 3‐(trimethoxysilyl) propyl methacrylate. It was found that the hybrid B films could significantly prevent macrophase separation, as evidenced by scanning electron and fluorescence microscopy. Furthermore, the thermal characteristics of the hybrid films were largely improved in comparison with the parent MEH‐PPV. The UV‐visible absorption spectra suggested that the incorporation of MSMA‐modified silica into MEH‐PPV could confine the polymer chain between nanoparticles and thus increase the conjugation length. The photoluminescence (PL) studies also indicated enhancement of the PL intensity and quantum efficiency by incorporating just 2 wt% of MSMA‐modified silica into MEH‐PPV. However, hybrid A films did not show such enhancement of optoelectronic properties as the hybrid B films. The present study suggests the importance of the interface between the luminescent organic polymers and the inorganic silica on morphology and optoelectronic properties. Copyright © 2004 Society of Chemical Industry 相似文献
7.
Human facial gestures often exhibit such natural stochastic variations as how often the eyes blink, how often the eyebrows and the nose twitch, and how the head moves while speaking. The stochastic movements of facial features are key ingredients for generating convincing facial expressions. Although such small variations have been simulated using noise functions in many graphics applications, modulating noise functions to match natural variations induced from the affective states and the personality of characters is difficult and not intuitive. We present a technique for generating subtle expressive facial gestures (facial expressions and head motion) semi‐automatically from motion capture data. Our approach is based on Markov random fields that are simulated in two levels. In the lower level, the coordinated movements of facial features are captured, parameterized, and transferred to synthetic faces using basis shapes. The upper level represents independent stochastic behavior of facial features. The experimental results show that our system generates expressive facial gestures synchronized with input speech. 相似文献
8.
文章通过对五口井的现场应用介绍,阐述了快速色谱分析技术在油气层识别和解释方面的准确性,探讨了该技术在薄油气层的发现和评价、快速钻进条件下油气层的发现、对油气层全烃组份变化的统一、水平井的地质导向以及排除钻井液添加荆对油气显示的影响五个方面的优势,从而论证了快速色谱分析技术在油气勘探中的应用价值。 相似文献
9.
Joel P. Martin J. Edward Swan II Robert J. Moorhead II Zhanping Liu Shangshu Cai 《Computer Graphics Forum》2008,27(3):991-998
We present the results from a user study looking at the ability of observers to mentally integrate wind direction and magnitude over a vector field. The data set chosen for the study is an MM5 (PSU/NCAR Mesoscale Model) simulation of Hurricane Lili over the Gulf of Mexico as it approaches the southeastern United States. Nine observers participated in the study. This study investigates the effect of layering on the observer's ability to determine the magnitude and direction of a vector field. We found a tendency for observers to underestimate the magnitude of the vectors and a counter‐clockwise bias when determining the average direction of a vector field. We completed an additional study with two observers to try to uncover the source of the counter‐clockwise bias. These results have direct implications to atmospheric scientists, but may also be able to be applied to other fields that use 2D vector fields. 相似文献
10.
No authorship indicated 《Canadian Metallurgical Quarterly》2007,62(5):391
Announces the 2007 recipient of the Gold Medal Award for Life Achievement in the Psychology in the Public Interest: Rhoda K. Unger. A brief biography, highlighting areas of special focus in Unger's work, is provided. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献