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排序方式: 共有470条查询结果,搜索用时 31 毫秒
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本研究以糙米为主要培养基并结合真空干燥(-0.1 MPa)和冷冻保藏(-80℃)工艺开发出一种米曲霉长期保藏技术。生产实验表明,利用该方法保藏20年的米曲霉菌种直接制备的大曲中中性蛋白酶、酸性蛋白酶、淀粉酶和葡萄糖淀粉酶的酶活分别达到1871、319、256和2110 U/g干曲。利用该大曲所生产的酱油总氮、氨基酸态氮、总糖、还原糖、无盐固形物含量及原料蛋白质利用率分别达到1.53、0.92、5.39、3.52、19.88 g/100 mL和82.20%。上述指标显著优于利用常规冻干管法保藏20年的米曲霉所制备大曲和酱油的相应指标(p0.05),与利用常规冻干管法保藏5年的米曲霉所制备大曲和酱油的相应指标无显著差异(p0.05)。由聚类分析可知,本方法可比冻干管法延长米曲霉保藏时间15年,在实际生产中可减少菌株复壮次数,避免传代过程中米曲霉突变和污染的几率,进而提高酱油质量稳定性。 相似文献
463.
采用红曲霉与啤酒酵母或米曲霉在液态大米粉培养基上混合培养。当紫红曲霉No.1-18—54培养1d后,加入啤酒酵母或米曲霉混合培养108h,色价明显提高,尤其是与啤酒酵母混合培养,红色素色价提高了32%,高达88.1U/mL。 相似文献
464.
产中性蛋白酶种曲培养基的优化及酶学特性研究 总被引:1,自引:0,他引:1
以中性蛋白酶活力为检验指标,采用响应面法对米曲霉产中性蛋白酶的种曲培养基进行优化,确定其最佳配方组成为:面粉用量2.24g,花生粕用量8.46g,氯化钙用量0.028g,种曲中性蛋白酶活力高达15559.40U/g。经研究纯化后中性蛋白酶酶学特性,发现中性蛋白酶的最适pH为7.0,在pH5.0-7.0范围内具有良好的稳定性;最适作用温度为50℃,在40-55℃条件下能保持较高的酶活力;试验金属离子对蛋白酶没有显著的激活作用,Ba^2+、Fe^2+、Zn^2+和Cu^2+具有显著的抑制作用。 相似文献
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The wild type strain Rhizopus oryzae PW352 was mutated by means of nitrogen ion implantation (15 keV, 7.8×10^14 ~ 2.08 ×10^15 ions/cm^2) to find an industrial strain with a higher L(+)-lactic acid yield, and two mutants RE3303 and RF9052 were isolated. In order to discuss the mechanism primarily, Lactate Dehydrogenase of Rhizopus oryzae was studied. While the two mutants produced L(+)-lactic acid by 75% more than the wild strain did, their specific activity of Lactate Dehydrogenase was found to be higher than that in the wild strain. The optimum temperature of Lactate Dehydrogenase in Rhizopus oryzae RF9052 was higher. Compared to the wild strain, the Michaelis constant (Km) value of Lactate Dehydrogenase in the mutants was Changed. All these changes show that L(+)-lactic acid production has a correlation with the specific activity of Lactate Dehydrogenase. The low-energy ions, implanted into the strain, may improve the specific activity of Lactate Dehydrogenase by influencing its gene structure and protein structure. 相似文献
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Chenghao Li Dai Shi Andrea K. Stone Yixiao Wang Janitha P. D. Wanasundara Takuji Tanaka Michael T. Nickerson 《Journal of the American Oil Chemists' Society》2023,100(7):529-538
In this study, the effects of solid-state fermentation (SSF), including strain (Aspergillus niger NRRL 334 and A. oryzae NRRL 5590) and fermentation time (24, 48, and 72 h) on the nutritional value of cold-pressed (CP) and hexane-extracted (HE) canola meals were examined. SSF increased the protein content of both types of meals (from ~36% to ~40%) while reducing the oil content of CP meals (from ~12% to 9%). There was a significant reduction (~80%) in the phytic acid content of both types of meals after fermentation using either fungi. Overall, fermented samples showed a decrease in the total phenolic content from 2.7–3.1 to ~1.0 mg gallic acid equivalents (GAE)/g dry meal (DM) (a ~65% reduction), of which specifically the HE meal fermented with A. niger sample had the greatest decrease from 3.1 to 0.6 mg GAE/g DM (~81% reduction). Seventy-two hours of fermentation decreased the in vitro protein digestibility (IVPD) of A. oryzae fermented meals. In contrast, a shorter fermentation time (24 h) increased the IVPD for most samples as compared to the controls (from ~72%–73% to 77%–81%), with the exception of the CP meal fermented with A. niger which had similar IVPD at all fermentation times. Overall, the changes indicate that SSF using A. niger or A. oryzae can be useful to positively modify the composition of different canola meals and improve their nutritional value by significantly increasing the protein content, decreasing the levels of antinutrients, while only slightly reducing IVPD. 相似文献
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