全文获取类型
收费全文 | 21313篇 |
免费 | 2445篇 |
国内免费 | 1344篇 |
专业分类
电工技术 | 1796篇 |
综合类 | 2395篇 |
化学工业 | 1662篇 |
金属工艺 | 851篇 |
机械仪表 | 1584篇 |
建筑科学 | 4438篇 |
矿业工程 | 1123篇 |
能源动力 | 669篇 |
轻工业 | 541篇 |
水利工程 | 1119篇 |
石油天然气 | 941篇 |
武器工业 | 342篇 |
无线电 | 2104篇 |
一般工业技术 | 2906篇 |
冶金工业 | 480篇 |
原子能技术 | 293篇 |
自动化技术 | 1858篇 |
出版年
2024年 | 94篇 |
2023年 | 335篇 |
2022年 | 618篇 |
2021年 | 794篇 |
2020年 | 788篇 |
2019年 | 683篇 |
2018年 | 614篇 |
2017年 | 747篇 |
2016年 | 864篇 |
2015年 | 895篇 |
2014年 | 1456篇 |
2013年 | 1262篇 |
2012年 | 1618篇 |
2011年 | 1782篇 |
2010年 | 1327篇 |
2009年 | 1428篇 |
2008年 | 1240篇 |
2007年 | 1474篇 |
2006年 | 1268篇 |
2005年 | 1046篇 |
2004年 | 757篇 |
2003年 | 705篇 |
2002年 | 628篇 |
2001年 | 529篇 |
2000年 | 385篇 |
1999年 | 297篇 |
1998年 | 288篇 |
1997年 | 215篇 |
1996年 | 198篇 |
1995年 | 147篇 |
1994年 | 144篇 |
1993年 | 87篇 |
1992年 | 64篇 |
1991年 | 52篇 |
1990年 | 52篇 |
1989年 | 34篇 |
1988年 | 32篇 |
1987年 | 20篇 |
1986年 | 20篇 |
1985年 | 21篇 |
1984年 | 17篇 |
1983年 | 11篇 |
1982年 | 15篇 |
1981年 | 7篇 |
1980年 | 12篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1959年 | 10篇 |
1958年 | 2篇 |
1956年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
31.
本文叙述了杨凌国际会展中心基桩静力载荷试验的试验过程 ;通过对三根灌注桩承载力的试验结果分析 ,认为后压浆技术对提高灌注桩单桩极限承载力有很大作用 相似文献
32.
33.
ARAM·ARIES SPM-Lite便携式遥测地震数据采集系统是加拿大GEO-X公司在2002年下半年推出的全新小型便携式地震数据采集系统。该仪器运用了当今最先进的计算机制造技术、网络化技术和微电子技术,除继承了ARAM-ARIES地震数据采集系统所有功能和技术外,它还简化了硬件结构,使体积更小,重量更轻,功能性更强。更加适应地矿、煤田、丛林和山区进行地震勘探。 相似文献
34.
Transmission of signals, whether on-chip or off-chip, places severe constraints on timing and extracts a large price in energy. New silicon device technologies, such as back-plane CMOS, provide a programmable and adaptable threshold voltage as an additional tool that can be used for low power design. We show that one particularly desirable use of this freedom is energy-efficient high-speed transmission across long interconnects using multi-valued encoding. Our multi-valued CMOS circuits take advantage of the threshold voltage control of the transistors, by using the signal-voltage-to-threshold-voltage span, in order to make area-efficient implementations of 4-PAM (pulse amplitude modulation) transceivers operating at high speed. In a comparison of a variety of published technologies, for signal transmission with interconnects of 10-15 mm length, we show up to 50% improvement in energy for on-chip signal transmission over binary encoding together with higher limits for operating speeds without a penalty in circuit noise margin. 相似文献
35.
The aim of this study was to investigate the drug‐loading effects on release and mechanical properties of a scleroglucan gel, with the intention of considering them in delivery systems formulations. The rheological and kinetic properties of a 2 % w/w scleroglucan gel matrix loaded with 0, 0.02, 0.04, 0.06, 0.2 and 0.4 % w/w of theophylline (Th, used as a model drug) were investigated. Rheological measurements were performed in a controlled‐stress rotational‐shear rheometer under isothermal conditions. For theophylline release from the gel a flat Franz cell was used and the kinetic parameters were derived applying a semi‐empirical power law. The influence of scleroglucan molar weight on kinetic and rheological behaviour was also studied. Results suggest two possible effects of drug loading on the gel network: in the 0.04–0.06 % w/w Th range a plasticizing effect and in the 0.2–0.4 % w/w Th range a rigidization effect. In the first range mentioned, the changes in the gel structural properties tested by means of rheological measurements are coincident with changes in drug‐release kinetics. Copyright © 2005 Society of Chemical Industry 相似文献
36.
Reinforced concrete slabs are among the most common structural elements. In spite of the large number of slabs designed and built, the effect of their details on their behavior under impact loads are not always appreciated or properly taken into account. This experimental study was aimed at understanding the dynamic behavior of structural concrete slabs under impact loading to improve the state of the art of protective design. This study investigated the effects of different types of slab reinforcements and the applied impact loads on the dynamic response and behavior of reinforced concrete slabs. 相似文献
37.
The present study is an investigation on the behaviors of concrete-filled thin-walled steel tubular members subjected to combined loading, such as compression and torsion, bending and torsion, compression, bending and torsion. ABAQUS software is used in this paper for the finite element analysis (FEA). A comparison of results calculated using this modeling shows generally good agreement with test results. The FEA modeling is then used to investigate the influence of important parameters that determine the ultimate strength of the composite members under combined loading, such as compression and torsion, bending and torsion, compression, bending and torsion. The parametric studies provide information for the development of formulae for calculating the ultimate strength of the composite members subjected to combined loading. 相似文献
38.
对称配筋小偏心受压构件的截面设计 总被引:4,自引:1,他引:3
对小偏心受压构件在对称配筋情况下的截面配筋计算,提出用最佳一次逼近多项式简化基本公式,直接按二次方程求解ξ的近似方法,具有精度高,相对误差小,计算方便等优点,可供工程设计人员参考。 相似文献
39.
介绍了选针片式小提花横机常见选针故障的各种原因,并对不同原因导致的选针故障提出了针对性解决方法。 相似文献
40.
嵌入式Web服务器在中小水电信息采集系统中的应用 总被引:1,自引:1,他引:0
中小水电站大多数建在偏远山区,并网管理难度非常大,解决中小水电站的信息传输是主要的技术难点之一。随着计算机技术的发展,嵌入式Web服务器技术在远程监控和实时通信系统中的应用越来越广泛。将Web技术引入中小水电站信息采集系统中,可以实现对中小水电站基于浏览器方式的远程监控。文中结合中小水电站通信结构,介绍了嵌入式Web服务器技术在中小水电站信息采集系统中的应用。 相似文献