全文获取类型
收费全文 | 15100篇 |
免费 | 1540篇 |
国内免费 | 558篇 |
专业分类
电工技术 | 343篇 |
技术理论 | 1篇 |
综合类 | 1238篇 |
化学工业 | 3883篇 |
金属工艺 | 306篇 |
机械仪表 | 230篇 |
建筑科学 | 1206篇 |
矿业工程 | 207篇 |
能源动力 | 196篇 |
轻工业 | 6271篇 |
水利工程 | 253篇 |
石油天然气 | 567篇 |
武器工业 | 92篇 |
无线电 | 403篇 |
一般工业技术 | 1148篇 |
冶金工业 | 216篇 |
原子能技术 | 60篇 |
自动化技术 | 578篇 |
出版年
2024年 | 64篇 |
2023年 | 217篇 |
2022年 | 368篇 |
2021年 | 511篇 |
2020年 | 499篇 |
2019年 | 460篇 |
2018年 | 436篇 |
2017年 | 601篇 |
2016年 | 579篇 |
2015年 | 648篇 |
2014年 | 885篇 |
2013年 | 953篇 |
2012年 | 1199篇 |
2011年 | 1215篇 |
2010年 | 891篇 |
2009年 | 876篇 |
2008年 | 701篇 |
2007年 | 988篇 |
2006年 | 838篇 |
2005年 | 731篇 |
2004年 | 548篇 |
2003年 | 553篇 |
2002年 | 463篇 |
2001年 | 324篇 |
2000年 | 283篇 |
1999年 | 253篇 |
1998年 | 185篇 |
1997年 | 130篇 |
1996年 | 116篇 |
1995年 | 131篇 |
1994年 | 104篇 |
1993年 | 87篇 |
1992年 | 90篇 |
1991年 | 58篇 |
1990年 | 53篇 |
1989年 | 35篇 |
1988年 | 25篇 |
1987年 | 30篇 |
1986年 | 14篇 |
1985年 | 20篇 |
1984年 | 9篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 10篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1972年 | 2篇 |
1968年 | 1篇 |
1957年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 20 毫秒
1.
Silvina Patricia Meriles Roxana Piloni Georgina Vanesa Cáceres María Cecilia Penci María Andrea Marín Pablo Ribotta Marcela Lilian Martínez 《International Journal of Food Science & Technology》2022,57(8):4689-4696
The study was conducted to evaluate the effect of non-traditional and highly available and nutrient-dense ingredients in the production of value-added crackers. The crackers were prepared by combining partially defatted chia flour, wheat germ, quinoa, and oat. The antioxidant activity and the polyphenol content were 7.0–8.4 times higher in crackers produced with non-traditional ingredients compared to the control snack. The hydroperoxide value indicated a low oxidative deterioration of the oil. The sample with 10% of partially defatted chia flour was selected for shelf-life test under storage conditions and sensory evaluation. Modified atmosphere exerted a protective effect on the lipid stability regardless of the incorporation of BHT to the formulation. All the evaluated attributes scored highly during consumer acceptance. The formulated cracker presented a relevant content of protein, dietary fibre and omega-3 and -6 fatty acids. Based on these results, the crackers containing non-traditional ingredients resulted in a product with a good potential for both consumer acceptance and outstanding nutritional benefits. 相似文献
2.
Wenfei Tian Yi Zheng Weiqun Wang Donghai Wang Michael Tilley Guorong Zhang Zhonghu He Yonghui Li 《Comprehensive Reviews in Food Science and Food Safety》2022,21(3):2274-2308
The health benefits of whole wheat consumption can be partially attributed to wheat's phytochemicals, including phenolic acids, flavonoids, alkylresorcinols, carotenoids, phytosterols, tocopherols, and tocotrienols. It is of increasing interest to produce whole wheat products that are rich in bioactive phytochemicals. This review provides the fundamentals of the chemistry, extraction, and occurrence of wheat phytochemicals and includes critical discussion of several long-lasting issues: (1) the commonly used nomenclature on distribution of wheat phenolic acids, namely, soluble-free, soluble-conjugated, and insoluble-bound phenolic acids; (2) different extraction protocols for wheat phytochemicals; and (3) the chemistry and application of in vitro antioxidant assays. This review further discusses recent advances on the effects of genotypes, environments, field management, and processing techniques including ultrafine grinding, germination, fermentation, enzymatic treatments, thermal treatments, and food processing. These results need to be interpreted with care due to varied sample preparation protocols and limitations of in vitro assays. The bioaccessibility, bioavailability, metabolism, and potential health benefits of wheat phytochemicals are also reviewed. This comprehensive and critical review will benefit scientific researchers in the field of bioactive compounds of cereal grains and also those in the cereal food industry to produce high-quality functional foods. 相似文献
3.
Dr. Chandan Pal Prof. Tushar Kanti Chakraborty 《Chembiochem : a European journal of chemical biology》2020,21(13):1837-1842
Among the non-canonical structures of B-DNA, the G-quadruplex is of particular interest because of its well-defined conformation, high stability, and versatility. Herein we report our studies on the development of an amide-linked minimal diguanosinyl motif that forms a G-quadruplex-like structure in solution in the presence of potassium cations; various linear guanosine amino acid dimers were synthesized with linkers of different chain lengths to investigate the optimum flexibility required to form such structures. 相似文献
4.
采用低温等离子体技术对海绵铁表面进行改性,并将其用于活化过硫酸盐(PS)处理含酚废水。通过氮气等温吸附(BET)、X射线衍射(XRD)和扫描电子显微镜(SEM)等手段对改性前后的海绵铁进行表征分析。以苯酚为目标污染物,通过静态实验考察催化剂投加量、催化剂/PS摩尔比、pH和苯酚初始浓度对等离子体改性海绵铁活化PS处理含酚废水的影响。结果表明,改性后的海绵铁比表面积、孔容及孔径均有增大,活化PS能力显著提高;在最佳反应条件(等离子改性海绵铁的投加量为0.4g/L,催化剂/PS摩尔比为1∶15,溶液pH为2,苯酚的初始浓度为250mg/L)下,苯酚的去除率可达95%;反应过程符合二级反应动力学,主要是硫酸根自由基和羟基自由基起氧化作用。等离子体技术改性海绵铁活化过硫酸钠可有效去除水中苯酚,为实际含酚废水的处理提供一些思路。 相似文献
5.
6.
7.
8.
改型Wollaston棱镜(MWP)无需中继,可构建微型傅里叶变换光谱仪。回顾了MWP的基本原理,从调制度定义出发,计算得到准单色光源的复相干度,找到调制度的影响因素——扩展视场、剪切结构、焦面探测等。建立一般的干涉定域分析模型后,由像点逆光路追迹给出MWP的厚度计算公式,代入调制度约束参数得到不同参量的误差容限。通过FRED记录不同视场扩展情况的灰度与辐照度,结果显示,调制度为0.9时,视场与理论估算值1.24°基本相符;不同剪切量的灰度与辐照度变化特性表明,结构角会使定域垂直系统光轴的入射角发生变化,与晶轴倾角共同影响双折射率差;2.5和8μm像元探测采样表现出调制度差异,描述了定域深度或离焦的影响。以准单色光源、复相干度表示调制度,可将不同影响因素统一至约束参数中,相关变量误差容限可作为MWP-FTS的设计依据。 相似文献
9.
10.
Variations in yield and gluten proteins in durum wheat varieties under late‐season foliar versus soil application of nitrogen fertilizer in a northern Mediterranean environment 下载免费PDF全文