全文获取类型
收费全文 | 777篇 |
免费 | 23篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 5篇 |
综合类 | 57篇 |
化学工业 | 129篇 |
金属工艺 | 5篇 |
机械仪表 | 1篇 |
建筑科学 | 29篇 |
矿业工程 | 20篇 |
能源动力 | 10篇 |
轻工业 | 411篇 |
水利工程 | 11篇 |
石油天然气 | 92篇 |
武器工业 | 1篇 |
无线电 | 6篇 |
一般工业技术 | 8篇 |
冶金工业 | 11篇 |
原子能技术 | 1篇 |
自动化技术 | 13篇 |
出版年
2022年 | 16篇 |
2021年 | 6篇 |
2020年 | 7篇 |
2019年 | 9篇 |
2018年 | 7篇 |
2017年 | 10篇 |
2016年 | 10篇 |
2015年 | 15篇 |
2014年 | 24篇 |
2013年 | 20篇 |
2012年 | 50篇 |
2011年 | 50篇 |
2010年 | 45篇 |
2009年 | 27篇 |
2008年 | 36篇 |
2007年 | 93篇 |
2006年 | 104篇 |
2005年 | 74篇 |
2004年 | 48篇 |
2003年 | 39篇 |
2002年 | 34篇 |
2001年 | 30篇 |
2000年 | 11篇 |
1999年 | 18篇 |
1998年 | 7篇 |
1997年 | 3篇 |
1996年 | 6篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1991年 | 1篇 |
排序方式: 共有810条查询结果,搜索用时 15 毫秒
1.
Dr. Kathrin Schindl Dr. Deepika Sharma Prof. Dr. Dieter Spiteller 《Chembiochem : a European journal of chemical biology》2020,21(21):3151-3157
When Streptomyces violaceoruber grows together with Streptomyces sp. MG7-G1, it reacts with strongly induced droplet production on its aerial mycelium. Initially the metabolite profile of droplets from S. violaceoruber in co-culture with Streptomyces sp. MG7-G1 was compared to samples from S. violaceoruber in single-culture by using high-performance liquid chromatography-mass spectrometry (HPLC-MS). Then, the exudate from agar plates of co-cultures and single cultures (after freezing and thawing) was also analysed. Several compounds were only observed when S. violaceoruber was grown in co-culture. Based on their high-resolution ESI mass spectra and their comparable retention times to the calcium-dependent antibiotics (CDAs) produced by S. violaceoruber, the new compounds were suspected to be deacylated calcium-dependent antibiotics (daCDAs), lacking the 2,3-epoxyhexanoyl residue of CDAs. This was verified by detailed analysis of the MS/MS spectra of the daCDAs in comparison to the CDAs. The major CDA compounds present in calcium ion-supplemented agar medium of co-cultures were daCDAs, thus suggesting that Streptomyces sp. MG7-G1 expresses a deacylase that degrades CDAs. 相似文献
2.
3.
LIU Guangzhen MA Zhanfang SHEN Jianquan 《武汉理工大学学报(材料科学英文版)》2006,21(4):16-18
1 IntroductionGold nanoparticles have attracted considerable atten-tionin manyfields duetotheir some special properties al-though goldis very popularfor beingchemicallyinert[1-3].For example ,gold nanoparticles as amplificationtags havebeenthe subject of research directed at gene analysis[4]and antibody or antigen detection[5-7]due to the large di-electric constant ,ease of preparation,andits biocompati-bility[8].Nanoparticles in the range of 1-10 nmin diameterwould display electronic structur… 相似文献
4.
5.
生物絮凝剂及其在水处理中的应用进展 总被引:7,自引:0,他引:7
介绍了微生物絮凝剂的种类、特点、絮凝机理和近几年来国内在不同废水处理中的应用情况,并对它的研究及应用前景做出展望。 相似文献
6.
To investigate species-specific decomposition rates of litter from native (Quercus faginea) and introduced (Eucalyptus globulus) tree species in Portugal, we monitored changes in the phenolic signature of leaf litter during decomposition as mediated by an aquatic, Proasellus coxalis (Isopoda: Asellota), and two terrestrial, Porcellio dispar and Eluma caelatum (Isopoda: Oniscidea), detritivores. Although the litter of Eucalyptus and Quercus did not differ in overall protein precipitation capacity, we detected differences in terms of contents of particular phenolic compounds and phenol oxidation products. Accordingly, we observed food-specific consumption rates in Proasellus, but not in the terrestrial isopods. Proasellus digested Eucalyptus at significantly higher rates than Quercus, whereas the opposite was the case for Eluma, and Porcellio digested both litter types equally well. Despite slight differences in detail, effects of Proasellus on changes in the signature of litter phenolics were similar for both litter types, whereas terrestrial isopods—Porcellio and Eluma, although they differed from each other—digestively degraded phenolic compounds in Eucalyptus and Quercus litter, respectively, in different ways. Overall, however, degradation of litter phenolics was similarly effective on both litter types. From these data, we conclude that decomposition of Eucalyptus litter does not proceed more slowly than of litter from native Portuguese trees. 相似文献
7.
8.
运用Plackett-Burman法确定了影响脂肽产量的3个重要因素:FeSO4、MnSO4和酵母粉,通过最陡爬坡试验确定了以上3个重要影响因素的最佳质量浓度范围,再利用Box-Behnken设计得出回归方程并利用Minitab软件进行回归分析,得到各因素的最佳质量浓度(g/L):FeSO40.011,MnSO40.204,酵母粉0.205,KH2PO43.4,Na2HPO41.5,NaNO34,MgSO4.7H2O 0.2,液体石蜡25。采用优化后的培养基进行发酵,发酵液的表面张力值降至38.4 mN/m,脂肽产量达到401 mg/L,提高了19.7%。 相似文献
9.
研究了投加酵母菌群、光合细菌群和混合菌群等多功能微生物菌群促进炼厂的剩余污泥的减量化效果。通过多次污泥减量试验,观察到在好氧消化基础上投加功能菌群能显著促进炼厂剩余污泥减量化。结果表明,与仅好氧曝气条件下相比,投加酵母菌群、光合细菌群、混合菌群的MLSS去除率明显提高了13.81%、30.58%、37.94%;投加功能菌群作用后的污泥沉降性能均优于投加前;pH值均逐渐降低。功能微生物降解效应使石油组分发生明显的变化,强化了对低中碳正构烷烃的降解程度,有利于将高碳链烃降解为低碳链烃。 相似文献
10.
微生物是影响材料尤其是金属材料腐蚀的主要因素之一.结合国内外的文献资料,介绍了易造成材料腐蚀的微生物的种类及微生物腐蚀的作用机理,阐述了微生物对材料腐蚀的现状,并说明了微生物腐蚀的危害和控制方法. 相似文献