全文获取类型
收费全文 | 29794篇 |
免费 | 2835篇 |
国内免费 | 1456篇 |
专业分类
电工技术 | 470篇 |
综合类 | 1586篇 |
化学工业 | 9676篇 |
金属工艺 | 1169篇 |
机械仪表 | 1458篇 |
建筑科学 | 1551篇 |
矿业工程 | 492篇 |
能源动力 | 974篇 |
轻工业 | 6515篇 |
水利工程 | 174篇 |
石油天然气 | 1786篇 |
武器工业 | 263篇 |
无线电 | 2051篇 |
一般工业技术 | 3323篇 |
冶金工业 | 1039篇 |
原子能技术 | 634篇 |
自动化技术 | 924篇 |
出版年
2024年 | 153篇 |
2023年 | 534篇 |
2022年 | 810篇 |
2021年 | 1164篇 |
2020年 | 1204篇 |
2019年 | 1213篇 |
2018年 | 1069篇 |
2017年 | 1178篇 |
2016年 | 1245篇 |
2015年 | 1194篇 |
2014年 | 1713篇 |
2013年 | 2015篇 |
2012年 | 2126篇 |
2011年 | 2109篇 |
2010年 | 1425篇 |
2009年 | 1446篇 |
2008年 | 1250篇 |
2007年 | 1670篇 |
2006年 | 1498篇 |
2005年 | 1323篇 |
2004年 | 1099篇 |
2003年 | 995篇 |
2002年 | 850篇 |
2001年 | 781篇 |
2000年 | 669篇 |
1999年 | 603篇 |
1998年 | 501篇 |
1997年 | 428篇 |
1996年 | 320篇 |
1995年 | 308篇 |
1994年 | 207篇 |
1993年 | 209篇 |
1992年 | 168篇 |
1991年 | 103篇 |
1990年 | 86篇 |
1989年 | 64篇 |
1988年 | 59篇 |
1987年 | 39篇 |
1986年 | 37篇 |
1985年 | 48篇 |
1984年 | 45篇 |
1983年 | 29篇 |
1982年 | 21篇 |
1981年 | 22篇 |
1980年 | 19篇 |
1978年 | 7篇 |
1976年 | 5篇 |
1974年 | 3篇 |
1959年 | 3篇 |
1951年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
THERMODYNAMICSANDPHASEEQUILIBRIUMOFCu-Y-O,Cu-Y-S,Cu-Y-O-SLIQUIDSOLUTIONS¥Du,Ting;Li,Guodong(CentralIronandSteelResearchinstit... 相似文献
32.
Abhishek K. Srivastava Vladimir G. Chigrinov Hoi Sing Kwok 《Journal of the Society for Information Display》2015,23(6):253-272
The ferroelectric liquid crystals, because of their fast electro‐optical response, are one of the most important classes of liquid crystals. Here, in this review, we have summarized the different electro‐optical modes for ferroelectric liquid crystals. Clark–Lagerwall effect (surface stabilized ferroelectric liquid crystal), deformed helix ferroelectric (DHF) effect, electrically suppressed helix (ESH) mode, DHF orientational Kerr effect, and ESH diffraction modes have been discussed. All of the crucial features, that is, optics, electro‐optics, dynamics, and their dependence on material parameters, operational regime, and applications, have been reviewed. 相似文献
33.
将常规的数字温度仪与压力计通过串行口和计算机连接,构建基于LabVIEW 8.0测定纯液体蒸发焓的虚拟仪器,实现实验数据的动态采集、实时显示、自动绘制p~T曲线并显示曲线方程、自动数据处理和写成结果报告等。应用结果表明:基于LabVIEW构建的测定纯液体蒸发焓的虚拟仪器,免除人工操作的繁琐和人为误差,测定乙醇和苯蒸发焓的相对误差分别为0.86%、-2.97%,提高了测量结果的准确度,且具有界面友好,操作简便和功能易扩展等诸多优点。 相似文献
34.
I. ledziska J. Sotysiak W. Staczyk 《Journal of Inorganic and Organometallic Polymers》1994,4(2):199-204
The synthesis and properties of individual liquid crystal oligo(cyclosiloxanes),, wherex=4–8 andR is a 4-methoxyphenyl-4-alkyloxybenzoate type of mesogenic group, is described. Preliminary results concerning the effect of ring size on the mesophase formation are included. X-ray diffraction studies have shown that the cyclosiloxanes form a smectic A1 phase. 相似文献
35.
This chapter focuses on multielectron reactions in organized assemblies of molecules at the liquid/liquid interface. We describe the thermodynamic and kinetic parameters of such reactions, including the structure of the reaction centers, charge movement along the electron transfer pathways, and the role of electric double layers in artificial photosynthesis. Some examples of artificial photosynthesis at the oil/water interface are considered, including water photooxidation to the molecular oxygen, oxygen photoreduction, photosynthesis of amphiphilic compounds and proton evolution by photochemical processes. 相似文献
36.
Yuan Deng Yihai Yang Yuanhang Xiao He-Lou Xie Ruochen Lan Lanying Zhang Huai Yang 《Advanced functional materials》2023,33(35):2301319
Switchable passive radiative cooling (PRC) smart windows can modulate sunlight transmission and spontaneously emit heat to outer space through atmospheric transparent window, presenting great potential in building energy conservation. However, realizing stable and on-demand control of the cooling efficiency for PRC materials is still challenging. Herein, an electro-controlled polymer-dispersed liquid crystal (PDLC) smart window showing PRC property is designed and prepared by adding mid-infrared emitting reactive monomers into the conventional PDLC matrix. It is found that not only the electro-optical properties but also the PRC efficiency of PRC PDLC film are tunable by regulating the content of the mid-infrared emitting components, film thickness, and micromorphology. This advanced PRC PDLC material achieves a near/sub-ambient temperature when the solar irradiance is below 400 W m−2 and can dynamically manage daytime cooling efficiency. Importantly, its PRC efficiency is capable of being tuned in an on-demand and ultrafast millisecond-scale way, whose controllable transparency enables multistage heat regulation. This study is hoped to provide new inspiration in the preparation of advanced optical devices and energy-efficient equipment. 相似文献
37.
38.
39.
J. W. Magee 《International Journal of Thermophysics》1998,19(5):1381-1395
The p--T relationships have been measured for 1,1-difluoroethane (R152a) and 1,1,1-trifluoroethane (R143a) by an isochoric method with gravimetric determinations of the amount of substance. Temperatures ranged from 158 to 400 K for R152a and from 166 to 400 K for R143a, while pressures were up to 35 MPa. Measurements were conducted on compressed liquid samples. Determinations of saturated liquid densities were made by extrapolating each isochore to the vapor pressure, and determining the temperature and density at the intersection. Published p--T data are in good agreement with this study. For the p--T apparatus, the uncertainty of the temperature is ±0.03 K, and for pressure it is ±0.01% at p>3 MPa and ±0.05% at p<3 MPa. The principal source of uncertainty is the cell volume (28.5 cm3), which has a standard uncertainty of ±0.003 cm3. When all components of experimental uncertainty are considered, the expanded relative uncertainty (with a coverage factor k=2 and thus a two-standard deviation estimate) of the density measurements is estimated to be ±0.05%. 相似文献
40.
基于测定推进剂A现有分析方法准确度低,神经网络法对仪器要求高等不足,提出了的一种新的分析方法。该方法利用已知酸的电位滴定数据建立多元线性回归数学模型,利用化学因子分解该模型,对未知样进行浓度测定。实际测定结果表明本方法的最大分析误差不超过0.17%,标准偏差不超过1.9%,满足样品分析要求。 相似文献