全文获取类型
收费全文 | 1313篇 |
免费 | 40篇 |
国内免费 | 55篇 |
专业分类
电工技术 | 24篇 |
综合类 | 57篇 |
化学工业 | 193篇 |
金属工艺 | 32篇 |
机械仪表 | 271篇 |
建筑科学 | 77篇 |
矿业工程 | 22篇 |
能源动力 | 29篇 |
轻工业 | 196篇 |
水利工程 | 20篇 |
石油天然气 | 305篇 |
武器工业 | 2篇 |
无线电 | 23篇 |
一般工业技术 | 49篇 |
冶金工业 | 56篇 |
原子能技术 | 9篇 |
自动化技术 | 43篇 |
出版年
2024年 | 10篇 |
2023年 | 13篇 |
2022年 | 25篇 |
2021年 | 41篇 |
2020年 | 48篇 |
2019年 | 36篇 |
2018年 | 52篇 |
2017年 | 41篇 |
2016年 | 38篇 |
2015年 | 45篇 |
2014年 | 68篇 |
2013年 | 68篇 |
2012年 | 65篇 |
2011年 | 100篇 |
2010年 | 65篇 |
2009年 | 56篇 |
2008年 | 56篇 |
2007年 | 77篇 |
2006年 | 85篇 |
2005年 | 65篇 |
2004年 | 67篇 |
2003年 | 56篇 |
2002年 | 52篇 |
2001年 | 27篇 |
2000年 | 22篇 |
1999年 | 17篇 |
1998年 | 21篇 |
1997年 | 17篇 |
1996年 | 16篇 |
1995年 | 11篇 |
1994年 | 8篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1979年 | 2篇 |
1972年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有1408条查询结果,搜索用时 15 毫秒
61.
通过常温下不同储藏方式的谷糙对照储藏试验表明;稻谷与糙米的储藏品质变化和粮情变化因储藏方式不同差异明显,而相同储藏方式与储藏条件下的稻谷糙米之间却差异较小.常温下的早籼稻谷,当水分在安全标准(13%)以内时,其糙米双低储藏与常规储藏是可行的. 相似文献
62.
63.
微生物油脂主要是微生物利用碳水化合物合成的甘油酯,其脂肪酸组成和植物油相近,有的还含有较丰富的多不饱和脂肪酸,具有广阔的开发应用前景。介绍了从微生物油脂中分离纯化具有功能性的多不饱和脂肪酸的方法,继而阐述了以微生物油脂为原料,甲醇作酯交换剂,在催化剂的作用下制备生物柴油的方法和技术。同时对微生物柴油的可行性进行了分析。 相似文献
64.
65.
Lysophosphatidic acid (lysoPtdOH) levels have previously been reported to decrease in rodents with short-term fasting. We investigated whether a 16 h fast would change expression of autotaxin, the predominant phospholipase D responsible for adipose-derived lysoPtdOH synthesis, or any of the lysophosphatidic acid receptors (1–6) in four white adipose tissue (WAT) depots and interscapular brown adipose tissue (BAT) in male C57Bl/6J mice fed ad libitum, or fasted for 16 h. Aside from small inductions of Lpar1 in epididymal WAT and Lpar2 in epididymal and inguinal WAT, no significant changes were observed in expression of the Lpar family members, or autotaxin in perirenal, retroperitoneal, epididymal, or inguinal WAT or BAT with fasting. Comparison of the relative expression of Lpar1-6 in various depots showed that Lpar6 was the predominant Lpar in both WAT and BAT, and suggests that further work on the adipose-specific role of Lpar6 is warranted. 相似文献
66.
67.
Michael Weinstock 《Architectural Design》2008,78(2):26-33
Architecture is on the cusp of systemic change, driven by the dynamics of climate and economy, of new technologies and new means of production. There is a growing interest in the dynamics of fluidity, in networks and in the new topologies of surfaces and soft boundaries. This is part of a general cultural response to the contemporary reconfiguration of the concept of ‘nature’ within the discourse of architecture; a change from metaphor to model, from ‘nature’ as a source of formal inspiration to ‘nature’ as a mine of interrelated dynamic processes that are available for analysis and digital simulation. Michael Weinstock presents an account of the dynamics of natural metabolisms, and suggests an agenda for the development of metabolic morphologies of buildings and cities. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
68.
Mirjam Frischknecht Theodorus H.E. Meuwissen Beat Bapst Franz R. Seefried Christine Flury Dorian Garrick Heidi Signer-Hasler Christian Stricker Anna Bieber Ruedi Fries Ingolf Russ Johann Sölkner Alessandro Bagnato Birgit Gredler-Grandl 《Journal of dairy science》2018,101(2):1292-1296
The accuracy of genomic prediction determines response to selection. It has been hypothesized that accuracy of genomic breeding values can be increased by a higher density of variants. We used imputed whole-genome sequence data and various single nucleotide polymorphism (SNP) selection criteria to estimate genomic breeding values in Brown Swiss cattle. The extreme scenarios were 50K SNP chip data and whole-genome sequence data with intermediate scenarios using linkage disequilibrium-pruned whole-genome sequence variants, only variants predicted to be missense, or the top 50K variants from genome-wide association studies. We estimated genomic breeding values for 3 traits (somatic cell score, nonreturn rate in heifers, and stature) and found differences in accuracy levels between traits. However, among different SNP sets, accuracy was very similar. In our analyses, sequence data led to a marginal increase in accuracy for 1 trait and was lower than 50K for the other traits. We concluded that the inclusion of imputed whole-genome sequence data does not lead to increased accuracy of genomic prediction with the methods. 相似文献
69.
70.
The brown pigment in sautéed onion was characterized by a microbiological procedure (involving microbial decolorization) and a chemical procedure (involving metal-chelating chromatography with a Sepharose 6B column). The suitability of the chemical procedure as a method for classifying brown pigments was also examined.The pigment from sautéed onion was about 40% decolorized by Coriolus versicolor IFO 30340, as were the model pigments caramel and model melanoidin (MM). The phenol-type model pigments (PTMP) were approximately 40-60% decolorized by Paecilomyces canadensis NC-1, but the sautéed-onion pigment, the MM and the caramel were merely 5% decolorized by it. The pigment from sautéed onion was separated into two components by Cu2+, Fe2+, or Zn2+-chelating chromatography, as were caramel and MM; the PTMP was not separated into multiple components by either Cu2+ or Fe2+-chelating chromatography. The results from both methods indicate that the pigment from sautéed onion is similar to MM and caramel but not the phenol-type pigment. 相似文献