全文获取类型
收费全文 | 6656篇 |
免费 | 643篇 |
国内免费 | 487篇 |
专业分类
电工技术 | 269篇 |
综合类 | 1105篇 |
化学工业 | 309篇 |
金属工艺 | 188篇 |
机械仪表 | 260篇 |
建筑科学 | 901篇 |
矿业工程 | 254篇 |
能源动力 | 192篇 |
轻工业 | 369篇 |
水利工程 | 848篇 |
石油天然气 | 215篇 |
武器工业 | 45篇 |
无线电 | 573篇 |
一般工业技术 | 331篇 |
冶金工业 | 223篇 |
原子能技术 | 26篇 |
自动化技术 | 1678篇 |
出版年
2024年 | 9篇 |
2023年 | 66篇 |
2022年 | 113篇 |
2021年 | 130篇 |
2020年 | 147篇 |
2019年 | 136篇 |
2018年 | 120篇 |
2017年 | 155篇 |
2016年 | 168篇 |
2015年 | 208篇 |
2014年 | 257篇 |
2013年 | 287篇 |
2012年 | 354篇 |
2011年 | 463篇 |
2010年 | 382篇 |
2009年 | 408篇 |
2008年 | 497篇 |
2007年 | 651篇 |
2006年 | 548篇 |
2005年 | 481篇 |
2004年 | 413篇 |
2003年 | 329篇 |
2002年 | 281篇 |
2001年 | 212篇 |
2000年 | 198篇 |
1999年 | 135篇 |
1998年 | 109篇 |
1997年 | 90篇 |
1996年 | 84篇 |
1995年 | 59篇 |
1994年 | 64篇 |
1993年 | 48篇 |
1992年 | 41篇 |
1991年 | 31篇 |
1990年 | 29篇 |
1989年 | 22篇 |
1988年 | 13篇 |
1987年 | 9篇 |
1986年 | 5篇 |
1984年 | 2篇 |
1983年 | 6篇 |
1981年 | 4篇 |
1976年 | 3篇 |
1974年 | 2篇 |
1965年 | 2篇 |
1963年 | 2篇 |
1962年 | 1篇 |
1961年 | 1篇 |
1955年 | 5篇 |
1954年 | 2篇 |
排序方式: 共有7786条查询结果,搜索用时 31 毫秒
991.
为解决超差双翻斗式雨量传感器在检定校准时精细定量调测问题,尤其针对:在大小雨强(4mm/min和1mm/min)测试时超差值为一正一负,目前只能通过目测观察法并依靠经验对容量调节螺母和定位螺母进行调节,这存在着一定的盲目性并且成功率低。提出了一套检定流程并利用红外光电传感器和步进电机模块,实现了上翻斗和计量翻斗的左右斗的翻动数据的定量测量以及定位螺母和容量调节螺母的自动调节,并且可自动记录和上传检定数据到上位机。结果表明:本系统能有效地判定和解决翻斗翻动平衡和协调性问题,并可为业务人员积累检定数据以便后续分析处理。 相似文献
992.
Bismark Sarkodie Collins Acheampong Benjamin Asinyo Xun Zhang Benjamin Tawiah 《Color research and application》2019,44(3):396-410
Novel treatments of pigments with inorganic materials have tremendous industrial and commercial prospects. Specific treatment of pigment has a marked effect on its behavior during application. The treatment allows a broad modification of the surface characteristics of pigment particles which leads to improved functionalities. Surface modification of pigments is achieved via coating, polymerization with modifying reagent, treatment with derivatives or polymers, which alter either the optical, conductivity or dispersibility during processing and application. These and many other distinguishing factors that affect the characteristics of pigments such as the class, crystal structure, particle morphology, particle size, hiding power, pigment volume concentration, surface character, and surface treatment have been reviewed. Various organic pigments such as those from fungus and bacteria, and the various families of pigment types such as metallic pigment, light interference, and diffractive pigments which presents decorative quality such as leafing, nonleafing, pearlscent, and Fabry‐Perot effects on substrates have also been reviewed in addition to those from inorganic sources with emphasis on the structure and physiochemical modifications using metal and nonmetal Ions. 相似文献
993.
994.
Manish Aggarwal 《国际智能系统杂志》2019,34(5):733-753
Attitudinal Choquet integral (ACI) extends Choquet integral (CI) through a consideration of a decision-maker's (DM's) attitudinal character. In this paper, we generalize ACI, and the resulting operator is termed as generalized ACI (GACI). GACI adds to the efficacy of the ACI in the representation of a DM's unique and complex attitudinal character. It also generates a vast range of exponential ACI operators, such as harmonic ACI, ACI, quadratic ACI, to name a few. We further present induced GACI to consider additional information that may be associated with the arguments of aggregation. The special cases of the proposed operators are investigated. The usefulness of the proposed operators in modelling human decision behavior is shown through a case study. 相似文献
995.
This study aims to investigate the defensible character of the Lahore railway station built in response to “the war of independence in 1857,” which greatly impacted the location and design of the building. This study demonstrates the integral role played by the railway station in the development of the new colonial city, which the British wants to be defensive in every aspect. Railways were introduced in Pakistan (India) soon after their inauguration in Britain. Beginning from the mode of transportation, the multifaced contribution of railways toward the urban growth, new architectural style, mode of construction, and technology cannot be recanted. The research is based on the documentation and analysis of the history of Lahore railway station design. First, this study uses primary and secondary data to offer a history of the Lahore railway station from its inception to final execution. Second, it explores the criteria adopted by the British for its site selection to make the station a defensible post. The research finding includes the visual features that enhanced the architectural character of the building. Qualitative methods are used including several other approaches, namely, literature review, archival data collection, analysis of photographs, and study of architectural drawings and old maps, to achieve the objectives. 相似文献
996.
997.
《International Journal of Hydrogen Energy》2021,46(74):36801-36810
Sodium 9,10-anthraquinone-2,6-disulfonate (Na2AQ26DS, 130 mAh g−1) with polyanionic character and two O–Na ionic bonds is used as an organic cathode for Li-ion batteries. Na2AQ26DS exhibits highly impressive cycle stability in ether electrolytes due to its polyanionic character and the effective suppression of solvent-molecule co-intercalation. In half cells (1–3.9 V vs. Li+/Li) using 1 M bis(trifluoromethanesulphonyl)imide lithium salt (LiTFSI) in 1,3-dioxolane/dimethoxyethane (DOL/DME), Na2AQ26DS delivers a highly stable specific capacity of 123 mAh g−1 at 50 mA g−1 for 900 cycles (6-month test) and realizes ∼69 mAh g−1 for 2800 cycles at 500 mA g−1. In the full cells with the reduced state (Li4TP) of lithium terephthalate (Li2TP) as the organic anode, the resulting Li4TP II Na2AQ26DS organic lithium-ion batteries (OLIBs) can display a highly stable average discharge capacity of 120 mAh g−1cathode for 100 cycles at 50 mA g−1 and ∼63 mAh g−1cathode for 1200 cycles at 500 mA g−1 in 0.2–3.3 V. 相似文献
998.
A novel technique for binarization with stroke preservation of faint characters in degraded documents is proposed. It works in a multi-scale framework with an adaptive–interpolative thresholding technique. Instead of computing a global threshold value, it computes the local threshold values for a small set of grid points by observing the intensity pattern of the pixels lying in the concerned grid cells. Estimated thresholds are used, in turn, to compute the threshold values of all the remaining pixels using a fast-yet-efficient interpolation procedure. To handle noises in degraded images, this grid-based adaptive thresholding is applied in successively reducing scales to obtain the near-optimal binarization as a set of connected components. After a post-processing meant for stroke preservation with these connected components, we get the final output. Exhaustive experimentation and comparison with other existing methods have been successfully carried out with benchmark datasets and also with our own datasets. 相似文献
999.
球笼式万向节的等速性 总被引:1,自引:0,他引:1
球笼式万向节在具有很大轴间角时仍能平稳传递转速和转矩,且具有等速性。从结构和投影几何学两方面证明了其等速性,并对主动轴和从动轴的线速度进行了分析,为设计开发不等偏心距球笼式万向节提供了理论基础。 相似文献
1000.
曾钊新 《机械工业高教研究》2007,(3):5-13
德性是科学的天然品格。学术虚假、学术盗窃、学术廉价、学术歧视是科学研究者当今尤为突出的道德过失。科研工作者的道德过失常常发生在学术阶段。学术是前进在真理路上的知识,是科学明星升空的前奏,是学问诞生的必经之路。因为真理是定型阶段,科学是完成阶段,谁是真理的发现者,谁是科学的创造者,已经定论,已经公认了。唯有学术阶段是动态的、未成型的、未归主的,所以争论者、沾光者、冒名者、扒窃者都云集在这个阶段作祟。这是知识治安的空白地带,是学术安全最没有保障的地带,是学术多发事端的地带。振兴科学,必须首先拯救研究者的学术良心,从而让他们自我纠正在学术阶段中的道德过失。 相似文献