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121.
Rafael Alique Pilar Luna Teresa Hernández M. Angel Martínez 《European Food Research and Technology》2009,229(4):661-669
Atomised hot water vapour at between 46 and 54 °C for 60 min was tested as a method of delaying ripening and extending shelf
life in cv “Fino de Jete” cherimoya fruit (Annona cherimola Mill.). Heat treatment at 46 °C stimulated the respiration rate and starch degradation, induced ethylene production, increased
the accumulation of soluble sugars and α-amylase activity, and moved the onset of ethylene production (OEP) forward. Treatment
at 50 °C, and especially at 52 °C, delayed the climacteric peak and the OEP, decreased sugar and organic acid accumulation,
and reduced α-amylase and invertase activity. The results obtained indicate that temperatures higher than 48 °C slowed physiological
processes and carbohydrate metabolism and extend the shelf life of the cherimoya fruits, while temperatures higher than 52 °C
blocked ripening irreversibly. 相似文献
122.
Wang Shujun Liu Hongyan Gao Wenyuan Chen Haixia Yu Jiugao Xiao Peigen 《Food chemistry》2006,99(1):30-37
The starches separated from four different Dioscorea opposita Thunb. cultivars were investigated for morphological, thermal, crystal, and physicochemical properties, such as amylose content, swelling power, solubility and water-binding capacity properties. Amylose content of D. oppositastarches from different cultivars ranged from 20.74% to 25.94%. The shape of starch granules separated from different D. opposita Thunb. cultivars varied from round to oval or elliptic. The mean particle diameter of starches ranged from 23.39 to 26.87 μm. The transition temperatures (To, Tp and Tc) and enthalpy of gelatinization (ΔHgel) were determined using differential scanning calorimetry (DSC). To, Tp and Tc varied from 73.6 to 74.8, 78.8 to 81.0, and 83.3 to 87.2 °C, respectively. D. opposita cv. Jinchengerhao starch showed the highest ΔHgel values (12.48 J/g) while D. opposita cv. Baiyu starch showed the lowest values (8.413 J/g). The crystal type of starches separated from different D. opposita cultivars was a typical CB-type pattern. The degrees of crystallinity of the four D. opposita cultivars starches were about 50.52%, 32.99%, 33.57% and 36.16%, respectively. 相似文献
123.
高取代度羧甲基淀粉醚的制备 总被引:6,自引:0,他引:6
通过正交设计的合成试验对影响羧甲基淀粉醚取代度的各因素及它们的交互作用进行了考察,通过方差分析检验它们的显著性,研究了各因素影响淀粉羧甲基化反应的机理。在所确立的最佳反应条件下一次醚化能制备取代度高达1.70的羧甲基淀粉醚。对高取代淀粉醚作为钻井泥浆降失水剂的性能进行了初步评价。 相似文献
124.
In the present study, the ultrasonication method was used to investigate the effect of ultrasonic energy on the hydrolysis of corn, rice, and wheat starch by using the alpha-amylase enzymes produced by Bacillus species and Bacillus licheniformis. The effects of sonifier operation variables such as duty cycle and acoustic power rate on the stability of alpha-amylase enzymes and hydrolysis degrees of three types of starches were investigated at a temperature of 40°C and pH 6.5. To determine the effect of temperature with sonication on the hydrolysis process, wheat starch hydrolysis experiments were also carried out at a temperature of 50°C. Then, the relation between duty cycle and enzyme stability during hydrolysis for each enzyme at 50°C was expressed by a zero-order inactivation model. 相似文献
125.
The effects of air humidity when drying with superheated steam (SHS) were examined considering displacement by SHS. A wetted raw starch sphere (ball) was used as the model material. It was found that the humidity profile strongly affects the mass change and properties of the products. The material became porous when it was dried with pure SHS from start to finish, which differs both from products dried with high-humidity air alone, and from products dried with air followed by SHS within a few minutes. A prediction method for adiabatic saturation temperature over a wide range of humidity is also proposed. 相似文献
126.
淀粉双酶传感器的研制 总被引:2,自引:0,他引:2
报导了一种测定淀粉的酶生物传感器法,它具有检测速度快、灵敏度高、操作简便、且样品需要量少等优点。酶生物传感器是由固定化的GOD、GA酶膜和氧电极组成,测试的最佳条件为温度30℃,pH=4.4,0.2mol/L醋酸缓冲液,响应时间2min。该法的精密度、准确度均良好,线性范围0.05%~0.8%。 相似文献
127.
小麦制粉是利用机械力作用将小麦胚乳与皮层和胚逐步分离后,再将其胚乳研磨成粉的过程。小麦籽粒中营养物质分布不均匀,在制粉过程中,受制粉系统、机械力作用、筛理分级等因素的影响,胚乳出现不同程度的破碎,不同粒度级的小麦粉营养组分含量及分布也存在着一定差异。同时,随着胚乳的破碎,细胞壁破裂、淀粉与蛋白分离,营养组分和酶的作用位点更多的暴露,从而提高营养组分的消化性和生物利用率。本文综述了制粉过程的相关因素对小麦粉营养品质影响机理研究现状,以了解小麦制粉过程中各营养素的变化和损失,为后续制粉过程中充分保留营养素、提高营养素利用率提供参考。 相似文献
128.
无机纳米助剂的使用效果分析 总被引:1,自引:0,他引:1
探讨使用无机纳米助剂提高浆膜和纱线性能的机理。采用无机纳米助剂KHM-01和淀粉进行煮浆、上浆、浆液成膜和退浆试验,利用等离子体发射光谱仪对上浆纱和退浆纱中纳米粒子的含量进行定量分析,采用红外光谱、红外透射和热重分析研究淀粉浆膜中纳米粒子与淀粉之间的作用,用纯棉坯布上浆的方式并利用红外光谱研究纳米粒子、淀粉和棉纤维之间的作用。指出:无机纳米助剂KHM-01通过纳米粒子与淀粉和棉纤维之间强烈的相互作用而提高了浆膜和纱线的性能,这种强烈的相互作用是因为纳米材料表面富含羟基。 相似文献
129.
The underlying reasons for three waxy rice varieties, Yang-fu-nuo (Y), Su-yu-nuo (S), and Guang-ling-xiang-nuo (G), having different flour pasting properties were examined. The pasting properties of the isolated waxy rice starches did not correlate with those of the corresponding waxy rice flours. Examining the pasting properties of the flours in 0.5 mM AgNO3 solution, treated with dithiothreitol and protease, suggested that rice protein and amylase activity were the main causes of the pasting property differences among the rice starches and flours. Starch isolated from Y flour had a larger proportion of A and B1 chains, longer average chain length and longer exterior chain length, which explained its higher gelatinisation temperature, higher pasting consistency, greater extent of retrogradation, and the firm texture of cooked Y rice. 相似文献
130.
Dialdehyde porous starch (DPS) was prepared by enzymatic hydrolysis and periodate oxidation. Urease was immobilized on DPS by several techniques including physical adsorption and covalent bonding. Optimum urease immobilization conditions for maximum enzyme activity were shown as following: immobilization pH 6.0, processing time of immobilization 25 h, immobilization temperature 25°C, aldehydic groups content 79.6% and ratio of supporter to urease 1:2 (w/v in g/mL). Temperature optimum of the free and immobilized urease were 60 and 70°C, respectively. The temperature curve of the immoblized urease was wider than that registered for the free urease. After being stored at ambient temperature for 42 days, the immobilized urease retained almost all of the original activity. DPS was found capable of holding the urease enzyme during a repeated cyclic test for ten times. An increase of the Km value for the immobilized urease was found. The foregoing data indicated that DPS is a fine supporter for urease and provided a basis for biosensor or bioreactor development with reduced costs and improved shelf life. 相似文献