全文获取类型
收费全文 | 93296篇 |
免费 | 2059篇 |
国内免费 | 703篇 |
专业分类
电工技术 | 1542篇 |
综合类 | 59篇 |
化学工业 | 14976篇 |
金属工艺 | 3780篇 |
机械仪表 | 2966篇 |
建筑科学 | 2152篇 |
矿业工程 | 543篇 |
能源动力 | 2222篇 |
轻工业 | 9984篇 |
水利工程 | 1062篇 |
石油天然气 | 2382篇 |
武器工业 | 43篇 |
无线电 | 7998篇 |
一般工业技术 | 19388篇 |
冶金工业 | 16667篇 |
原子能技术 | 2714篇 |
自动化技术 | 7580篇 |
出版年
2022年 | 792篇 |
2021年 | 1353篇 |
2020年 | 1105篇 |
2019年 | 1238篇 |
2018年 | 2318篇 |
2017年 | 2290篇 |
2016年 | 2497篇 |
2015年 | 1528篇 |
2014年 | 2308篇 |
2013年 | 4988篇 |
2012年 | 3490篇 |
2011年 | 3835篇 |
2010年 | 3244篇 |
2009年 | 3443篇 |
2008年 | 3418篇 |
2007年 | 3289篇 |
2006年 | 2686篇 |
2005年 | 2305篇 |
2004年 | 2260篇 |
2003年 | 2156篇 |
2002年 | 2033篇 |
2001年 | 1924篇 |
2000年 | 1884篇 |
1999年 | 1833篇 |
1998年 | 5115篇 |
1997年 | 3519篇 |
1996年 | 2513篇 |
1995年 | 1819篇 |
1994年 | 1570篇 |
1993年 | 1632篇 |
1992年 | 1083篇 |
1991年 | 1133篇 |
1990年 | 1149篇 |
1989年 | 1131篇 |
1988年 | 1016篇 |
1987年 | 930篇 |
1986年 | 943篇 |
1985年 | 1013篇 |
1984年 | 822篇 |
1983年 | 807篇 |
1982年 | 728篇 |
1981年 | 752篇 |
1980年 | 712篇 |
1979年 | 670篇 |
1978年 | 647篇 |
1977年 | 868篇 |
1976年 | 1117篇 |
1975年 | 595篇 |
1974年 | 566篇 |
1973年 | 556篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
72.
73.
74.
75.
76.
Effect of complexation of oxidised corn starch with mineral elements on physicochemical properties 下载免费PDF全文
Sławomir Pietrzyk Teresa Fortuna Lesław Juszczak Dorota Gałkowska Karolina Królikowska Karolina Zięba 《International Journal of Food Science & Technology》2015,50(4):934-941
The objective of this study was to determine the effect of complexation of oxidised starch with mineral elements on its physicochemical properties. Corn starch was oxidised with sodium hypochlorite and, afterwards, modified with ions of potassium, magnesium and iron. Thus, native and modified starches were analysed for: contents of mineral elements, colour parameters (L*a*b*), water binding capacity and solubility in water at temperature of 60 and 80 °C. Thermodynamic characteristics of gelatinisation by DSC, molecular weight distribution by GPC, intrinsic viscosity and pasting properties by RVA were studied. The efficiency of incorporation of metal ions into oxidised corn starch was about 30%, 20% and 20% for potassium, magnesium and iron ions, respectively. The complexation with potassium ions caused the greatest changes in the molecular weight distribution and the intrinsic viscosity of starches and viscosity of starch pastes. Only modification of starch with iron ions affected the colour parameters of the starch. Incorporation of metal ions into starch resulted also in changes in its water binding capacity and solubility in water. 相似文献
77.
In this study, further analysis of the osmotic drying process was conducted to identify the optimum combination of parameters for drying rectangular alumina-gelatin beams. This study was designed to determine the effect of three variables related to the osmotic drying process (osmotic pressure, molecular weight, and immersion time) on the interaction between the liquid desiccant and the submerged alumina-gelatin samples. The water loss from the alumina-gelatin samples was positively correlated with the molecular weight, osmotic pressure, and immersion time. Up to 40% by weight of the initial water content was removed during the osmotic drying process. The samples also experienced solids gain due to the counterflow of solute from the liquid desiccant. The least amount of solids gain resulted from drying for the shortest immersion time at low osmotic pressure and high molecular weight. Evidence of possible interactions between variables was noted for the sintered density metric. Statistical methods were used to form regression equations for the measured responses (water loss, solids gain, bulk density). A verification experiment was conducted to compare the experimental outcomes to the predicted outcomes. The responses were simultaneously optimized to identify the combination of variable settings required to meet specified goals. In order to maximize water loss, minimize solids gain, and maximize bulk density, the ceramic-gelatin object should be immersed for approximately 60?min in an aqueous solution of 100,000?g/mol poly(ethylene oxide) at an osmotic pressure of 2.50?MPa. These values are valid for the range of parameter settings tested and the sample fabrication and drying methods used. 相似文献
78.
O.N. Kondrateva G.E. Nikiforova A.V. Tyurin M.A. Ryumin V.M. Gurevich A.P. Kritskaya K.S. Gavrichev 《Ceramics International》2018,44(15):18103-18107
The heat capacity of ytterbium orthovanadate was first measured by adiabatic calorimetry in the temperature range T?=?12.28–344.06?K. No obvious anomalies were observed on the curve obtained. The values of standard thermodynamic functions in the temperature range T?=?0–400 K were calculated. Based on low-temperature calorimetry data obtained, previously published data on the high-temperature heat capacity of ytterbium orthovanadate were corrected. The anomalous contribution to heat capacity for YbVO4 was compared with the data known for YbPO4. 相似文献
79.
H. Cherfouh O. Fellahi T. Hadjersi B. Marsan 《International Journal of Hydrogen Energy》2018,43(6):3431-3440
This work aims at developing a new composite material based on nanosized semiconducting CuInS2 (CIS) particles combined with silicon nanowires grown on a silicon substrate (SiNWs/Si) for photoelectrochemical (PEC)-splitting of water. The CIS particles were prepared via a colloidal method using N-methylimidazole (NMI) as the solvent and an annealing treatment. The SiNWs were obtained by chemical etching of silicon (100) substrates assisted by a metal. The CIS/SiNWs/Si composite material was obtained by deposition of an aliquot of a suspension of CIS particles onto the SiNWs/Si substrate, using spin coating followed by a drying step. The XRD pattern demonstrated that CuInS2 grows in the tetragonal/chalcopyrite phase, while SiNWs/Si presents a cubic structure. The SEM images show semi-spherical particles (~10 nm) distributed on the surface of silicon nanowires (~10 μm). The EIS measurements reveal n-type conductivity for CIS, SiNWs/Si and CIS/SiNWs/Si materials, which could favour the oxidation reaction of water molecules. 相似文献