全文获取类型
收费全文 | 439篇 |
免费 | 36篇 |
国内免费 | 37篇 |
专业分类
电工技术 | 38篇 |
综合类 | 52篇 |
化学工业 | 134篇 |
金属工艺 | 24篇 |
机械仪表 | 4篇 |
建筑科学 | 27篇 |
矿业工程 | 2篇 |
能源动力 | 41篇 |
轻工业 | 97篇 |
水利工程 | 3篇 |
石油天然气 | 6篇 |
武器工业 | 4篇 |
无线电 | 7篇 |
一般工业技术 | 45篇 |
冶金工业 | 10篇 |
原子能技术 | 7篇 |
自动化技术 | 11篇 |
出版年
2023年 | 6篇 |
2022年 | 11篇 |
2021年 | 8篇 |
2020年 | 13篇 |
2019年 | 13篇 |
2018年 | 4篇 |
2017年 | 6篇 |
2016年 | 18篇 |
2015年 | 19篇 |
2014年 | 15篇 |
2013年 | 29篇 |
2012年 | 19篇 |
2011年 | 28篇 |
2010年 | 28篇 |
2009年 | 27篇 |
2008年 | 22篇 |
2007年 | 20篇 |
2006年 | 31篇 |
2005年 | 19篇 |
2004年 | 26篇 |
2003年 | 16篇 |
2002年 | 14篇 |
2001年 | 22篇 |
2000年 | 15篇 |
1999年 | 11篇 |
1998年 | 13篇 |
1997年 | 11篇 |
1996年 | 8篇 |
1995年 | 9篇 |
1994年 | 7篇 |
1993年 | 7篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1986年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有512条查询结果,搜索用时 125 毫秒
21.
针对商业化的圆柱型18650锂离子电池,对其在充放电过程中的可逆及不可逆产热参数分别进行测试和计算,结合绝热加速量热仪(ARC)对电池放热的实测数据进行拟合分析,结果表明:根据该测试方法计算的可逆及不可逆产热数值与实测值具有很好的吻合性;该电池在0.3 C充放电过程中的总产热功率变化情况由可逆产热功率决定;可逆产热功率在电池荷电态为20%~60%区间内呈现出一个最高峰,对应电池发生熵变的脱嵌锂电化学主反应;不可逆产热功率在低荷电态下较高,而在其他荷电区间内变化幅度较小;电池在充放电过程中的总产热功率曲线是以不可逆产热功率曲线为对称轴,而在形状上基本呈现为上下对称。 相似文献
22.
Guidelines for the Synthesis of Small‐Molecule Irreversible Probes Targeting G Protein‐Coupled Receptors 下载免费PDF全文
Irreversible probes have been proven to be useful pharmacological tools in the study of structural and functional features in drug receptor pharmacology. They have been demonstrated to be particularly valuable for the isolation and purification of receptors. Furthermore, irreversible probes are helpful tools for the identification and characterization of binding sites, thereby supporting the advancement of rational drug design. In this Minireview, we provide insight into universal strategies and guidelines to successfully synthesize irreversible probes that target G protein‐coupled receptors (GPCRs). We provide an overview of commonly used chemoreactive and photoreactive groups, and make a comparison of their properties and potential applications. Furthermore, there is a particular focus on synthetic approaches to introduce these reactive groups based on commercially available reagents. 相似文献
23.
投资机会成本量化的期权方法探讨 总被引:1,自引:1,他引:1
在传统的项目投资决策理论中,进行项目的可行性研究时,一个决定性的指标是净现值(NPV),认为只要NPV>0,那么项目是可行的,而NPV的计算基础是初始的有形实际投入加上对未来收益现金流的预期。这种方法存在着不科学性:初始投入只考虑了有形投入,而没有考虑由于未来收益具有不确定性而产生的机会成本。拟采用期权的方法对传统的投资方法进行修正,力图使投资决策做到更加科学。 相似文献
24.
气液填料反应塔的设计计算式大都没有解析解,一般只有数值解或用图解积分计算,既费时,又费力。本文导出了飞速不可逆反应和快速拟一级不可逆反应这两种特定情况下的解析计算式,可直接用于填料反应塔的设计计算。 相似文献
25.
从不可逆热力学角度出发,建立了有一定通用性、能涵盖各类冻融损伤要素的熵产理论分析方法。基于经典Pennes生物传热方程,导出了描述活体组织传热过程熵产率的热力学模型,初步提出了用以刻画低温手术过程中组织冻融损伤程度的公式,在此基础上,采用有限元数值计算并借助熵产公式,就血液灌注率、代谢产热及手术时间等因素对手术疗效的影响进行了考察,为从组织层次定量刻画低温手术过程中的冻融损伤提供了新的理论途径。 相似文献
26.
以转炉连续检测的烟气成分为过程参数,以质量平衡理论和不可逆过程的非平衡态热力学理论为基础建立转炉过程动态模型,推算吹炼过程熔池碳含量和温度.通过建立模型过程中引入氧枪枪位,并对烟气的流量、系统滞后时间进行校正,以及运用不可逆过程热力学确定熔池的反应温度,有效提高了模型的精度. 相似文献
27.
Amonrat Thanonkaew Soottawat Benjakul Wonnop Visessanguan Eric A. Decker 《Food chemistry》2007,102(1):219-224
Lipid oxidation, discoloration, loss of amine groups and pyrrolization of the liposome systems of cuttlefish (Sepia pharaonis) in the presence of FeCl3 and ascorbic acid were studied. Thiobarbituric acid-reactive substances (TBARS) and the b∗-value of cuttlefish liposomes increased with a coincidental decrease in amine groups when the incubation temperatures (0, 4, 25, and 37 °C) and incubation times (0–24 h) were increased (p < 0.05). As lipid oxidation and yellow pigment formation in the cuttlefish liposome proceeded, a loss of amine groups and pyrrolization were also detected. The effects of FeCl3 and ascorbic acid, at different concentrations, on TBARS production, b∗-value, loss of amine groups and pyrrolization of cuttlefish liposome were also investigated. Both FeCl3 and ascorbic acid showed prooxidative effects in cuttlefish liposome in a concentration-dependent manner. Sodium chloride (0–2%) reduced TBARS, b∗-values and pyrrole compounds. These results suggest a positive correlation between lipid oxidation and the development of yellow pigments in cuttlefish phospholipids. 相似文献
28.
Hygroscopic Coatings Control Surface White Discoloration of Peeled (Minimally Processed) Carrots During Storage 总被引:1,自引:0,他引:1
LUIS CISNEROS-ZEVALLOS MIKAL E. SALTVEIT JOHN M. KROCHTA 《Journal of food science》1997,62(2):363-366
White discoloration on peeled carrots is partially due to surface dehydration which can be controlled with hygroscopic coatings: e.g., polyhydric alcohols and salt solutions. This study was performed at 2.5, 7.5, 10, and 15°C, using a model system controlling relative humidity at 33, 75 or 98% or a commercial system with low-density polyethylene (LDPE) plastic film bags. The moisture sorption properties of propylene glycol, sorbitol, glycerol and calcium chloride enabled them to keep the carrot surface moist and maintain a transparent surface layer through which the underlying orange color was visible. This effect was only observed at high relative humidities (e.g., 98% RH). Similar effects were observed on treated peeled carrots stored in LDPE bags. The moisturized appearance provided by the hygroscopic coatings during storage was effective at several different temperatures. 相似文献
29.
30.
Soret-driven species transport causes concentration non-uniformities in the immediate vicinity of ‘cold’ surfaces immersed in undersaturated vapor-containing streams. These concentration non-uniformities, in turn, alter corresponding condensation onset temperatures, often by as much as 30 K (i.e., ca. 3%) in previously studied, near-atmospheric pressure combustion systems [see, e.g., Rosner, D.E. and Nagarajan, R., 1985. Chemical Engineering Science 40 (2), 177]. Because high-pressures often cause remarkable increases in the relevant binary Soret factor, αT,12, we investigate here the importance of these vapor phase ‘transport’ effects for ‘compressed’ N2 streams containing dilute quantities of an alkane: C12H26 (n-dodecane) or C8H18 (n-octane). We invoke the virial equation of state (VES) to predict gas phase non-ideality, and its appreciable effect on previously available ideal gas Soret factors. Our illustrative numerical results, valid for, say, nominally 1000 K N2 streams up to pressures of over 100 atm, reveal that high-pressure Soret ‘shifts’ in Tdp can amount to ca. 80%, even at surface temperatures above the equilibrium freezing points of these condensates. We conclude that these high-pressure vapor phase transport phenomena will not only influence the interpretation of such hot gas/‘cold’ surface ‘dew-point’ measurements, they will significantly raise the temperatures at which containment or immersed surfaces must be maintained to avoid the ravages of corrosive or insulating inorganic condensates [Rosner, D.E., Chen, B.K., Fryburg, G.C., Kohl, F.J., 1979. Combustion Science and Technology 20, 87; Rosner, D.E., 1988a. Invited paper, Benjamin G. Levich Memorial Issue of Journal of Physico-Chemical Hydrodynamics 10 (5/6), 663]. In principle, the present theory could itself be used to study the pressure dependence of the binary Soret factor—at least for systems with well-characterized saturation vapor pressures. 相似文献