全文获取类型
收费全文 | 258篇 |
免费 | 10篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 78篇 |
金属工艺 | 3篇 |
机械仪表 | 5篇 |
建筑科学 | 7篇 |
矿业工程 | 2篇 |
能源动力 | 16篇 |
轻工业 | 16篇 |
水利工程 | 3篇 |
石油天然气 | 1篇 |
无线电 | 17篇 |
一般工业技术 | 38篇 |
冶金工业 | 23篇 |
原子能技术 | 4篇 |
自动化技术 | 53篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 7篇 |
2021年 | 19篇 |
2020年 | 11篇 |
2019年 | 13篇 |
2018年 | 14篇 |
2017年 | 10篇 |
2016年 | 18篇 |
2015年 | 11篇 |
2014年 | 14篇 |
2013年 | 18篇 |
2012年 | 14篇 |
2011年 | 21篇 |
2010年 | 17篇 |
2009年 | 14篇 |
2008年 | 7篇 |
2007年 | 14篇 |
2006年 | 2篇 |
2005年 | 10篇 |
2004年 | 3篇 |
2003年 | 5篇 |
2002年 | 2篇 |
2001年 | 5篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有270条查询结果,搜索用时 10 毫秒
111.
Frederick F. Twigg Dr. Wenlong Cai Dr. Wei Huang Joyce Liu Dr. Michio Sato Tynan J. Perez Jiaxin Geng Moriel J. Dror Ismael Montanez Tate L. Tong Hyunsu Lee Prof. Dr. Wenjun Zhang 《Chembiochem : a European journal of chemical biology》2019,20(9):1145-1149
Triacsins are a family of natural products having in common an N-hydroxytriazene moiety not found in any other known secondary metabolites. Though many studies have examined the biological activity of triacsins in lipid metabolism, their biosynthesis has remained unknown. Here we report the identification of the triacsin biosynthetic gene cluster in Streptomyces aureofaciens ATCC 31442. Bioinformatic analysis of the gene cluster led to the discovery of the tacrolimus producer Streptomyces tsukubaensis NRRL 18488 as a new triacsin producer. In addition to targeted gene disruption to identify necessary genes for triacsin production, stable isotope feeding was performed in vivo to advance the understanding of N-hydroxytriazene biosynthesis. 相似文献
112.
Janire Orcajo Ismael Marcet Benjamín Paredes Mario Díaz 《Food and Bioproducts Processing》2013,91(4):457-463
Given its low-cholesterol content feature, granules from egg yolk can be used as a substitute of the whole egg yolk. However, the functional properties of the granular fraction should be improved. In this sense, hydrolysis of proteins frequently produces improvements in some of its nutritional and technological properties. For that reason, in this work egg yolk granules were treated with a proteolytic enzyme, trypsin (E.C. 3.4.21.4) with the purpose of making a comparative characterization of the products.Results showed that the enzymatic reaction produced a degree of hydrolysis of 12%, being the size of the different peptides obtained and quantified by chromatographic and electrophoretic techniques. Mayonnaises made with these hydrolysed granules resulted more stable to temperature changes between 4 and 20 °C than the one made with non-hydrolysed ones. In the rheological tests carried out, the mayonnaise elaborated with hydrolysed granules has the most similar rheological behaviour to that of a commercial one used as reference. In general, the results obtained suggest that the recipe elaborated with hydrolysed granules had better rheological characteristics than those prepared using non-hydrolysed granules, maintaining the low-cholesterol feature. 相似文献
113.
Esteve V Canela N Rodriguez-Vilarrupla A Aligué R Agell N Mingarro I Bachs O Pérez-Payá E 《Chembiochem : a European journal of chemical biology》2003,4(9):863-869
The cyclin-dependent kinase inhibitory protein p21(Cip1) might play multiple roles in cell-cycle regulation through interaction of its C-terminal domain with a defined set of cellular proteins such as proliferating cell nuclear antigen (PCNA), calmodulin (CaM), and the oncoprotein SET. p21(Cip1) could be described as an intrinsically unstructured protein in solution although the C-terminal domain adopts a well-defined extended conformation when bound to PCNA. However, the molecular mechanism of the interaction with CaM and the oncoprotein SET is not well understood, partly because of the lack of structural information. In this work, a peptide derived from the C-terminal domain of p21(Cip1) that covers the binding domain of the three above-mentioned proteins was used to demonstrate that the C-terminal domain of p21 recognizes multiple ligands through its ability to adopt multiple conformations. The conformation is dictated by tertiary contacts rather than by the primary sequence of the protein. Our results suggest that the C-terminal domain of p21(Cip1) adopts an extended structure when bound to PCNA and probably when bound to the oncoprotein SET, but an alpha helix when bound to CaM. 相似文献
114.
Tinja Olenius Theo Kurtén Oona Kupiainen-Määttä Henning Henschel Ismael K. Ortega Hanna Vehkamäki 《Aerosol science and technology》2014,48(6):593-603
We used quantum chemical formation free energies of hydrated sulfuric acid-containing molecular clusters and a dynamic model to simulate a flow tube measurement, and determined the effective diffusion coefficient of sulfuric acid as a function of relative humidity. This type of measurement was performed by Hanson and Eisele, who presented and applied a fitting method to obtain equilibrium constants K1 and K2 for the formation of sulfuric acid mono- and dihydrates, respectively, from the experimentally determined diffusion coefficients. The fit is derived assuming that only H2SO4 molecules hydrated by up to two water molecules are present. To study the sensitivity of the results to this assumption, we implemented the same fit to the modeled diffusion coefficient data, computed including also larger H2SO4 hydrates with more than two waters. We show that according to quantum chemical equilibrium constants, the larger hydrates are likely to be present in nonnegligible amounts, which affects the effective diffusion coefficient. This results in the fitted value obtained for K1 being lower and for K2 being higher than the actual values. The results are further altered if contaminant base molecules, such as amines, capable of binding to H2SO4 molecules, are able to enter the system, for example, with the water vapor. The magnitude and direction of the effect of the contaminants depends not only on the contaminant concentration, but also on the H2SO4 concentration and on the hygroscopicity of the H2SO4–base clusters.
Copyright 2014 American Association for Aerosol Research 相似文献
115.
Freitas Júnior IF Rupp de Paiva SA de Godoy I Smaili Santos SM Campana AO 《Archivos latinoamericanos de nutrición》2005,55(2):124-131
The aim of this study was to examine the agreement between the results of body fat (BF and BF%), fat-free mass (FFM) and FFM index (FFMI= FFM/height2) as estimated by skinfold anthropometry (ANT), bioelectrical impedance (BIA) and dual-energy X-ray absorptiometry (DXA) in two groups of men (> or = 50 y), one comprising healthy individuals (n=23) and the other, patients with chronic obstructive pulmonary disease (COPD) (n=24). Comparisons between body composition techniques were done by repeated measures ANOVA; the Bland & Altman procedure was used to analyse agreement. RESULTS AND CONCLUSIONS: 1) comparison between healthy and COPD groups showed significant differences between all studied variables; 2) in the healthy group, values for BF, BF%, FFM and FFMI were not significantly different when BIA or ANT was compared to DXA; however, in COPD, values for BF and BF% were significantly higher and for FFM and FFMI significantly lower when BIA was compared to DXA; in contrast, no differences were shown between values for these variables when ANT was compared with DXA; 3) Bland & Altman test, in both groups, showed no agreement between BIA and DXA and between ANT and DXA; it was also shown that body fat was overestimated and fat free mass underestimated by BIA in relation to DXA. 相似文献
116.
Camp and Stein’s velocity gradient definition and its application to the study of fine sediment flocculation under flow shear are revised in the light of basic fluid mechanics concepts. Local motion and energy dissipation of a viscous fluid under laminar flow are used to prove that the Camp and Stein analysis was inaccurate for a general laminar movement. A generalization of Smoluchowski local aggregation equation and an alternative deduction for the parameter that Camp and Stein called velocity gradient are presented for a general laminar flow. 相似文献
117.
Single protein junctions consisting of azurin bridged between a gold substrate and the probe of an electrochemical tunneling microscope (ECSTM) have been obtained by two independent methods that allowed statistical analysis over a large number of measured junctions. Conductance measurements yield (7.3 ± 1.5) × 10(-6)G(0) in agreement with reported estimates using other techniques. Redox gating of the protein with an on/off ratio of 20 was demonstrated and constitutes a proof-of-principle of a single redox protein field-effect transistor. 相似文献
118.
119.
Different fuels are being used daily in the city of Kirkuk, Iraq for operating vehicles with spark-ignition internal combustion engines. Aiming to address the effects of these fuels on both engines and the environment, this work conducts an experimental study where a single-cylinder, four-stroke small spark ignition engine is employed. Three types of benzene with different octane ratings (low with an additive [85.8%], medium [89.2%], and high [95.6%]) are utilized in the study as they are the most consumed fuel in the area of the study. Moreover, the low-octane fuel will be addressed with a commercial additive. In addition to engine performance, the exhaust gases and sound levels are analyzed as well. Through the outcomes, it is observed that the fuel with higher octane numbers relatively produces better engine performance and pollution. At normal engine speed, the fuel with a medium octane rating, however, has close engine performance results but with worse pollution effects. On the other hand, the engine fails to start with low-octane fuel without the additive. The additive improves the engine performance with the low octane fuel and surprisingly produces fewer pollution gases than the fuel with medium octane number. However, the engine still behaves worse than with the other fuels at normal engine speed. 相似文献
120.
Rola H. Ali Makia J. Marafie Milad S. Bitar Fahad Al-Dousari Samar Ismael Hussain Bin Haider Waleed Al-Ali Sindhu P. Jacob Fahd Al-Mulla 《International journal of molecular sciences》2014,15(10):17344-17365
Gender-related differences in colorectal cancer (CRC) are not fully understood. Recent studies have shown that CRC arising in females are significantly associated with CpG island methylator phenotype (CIMP-high). Using array comparative genomic hybridization, we analyzed a cohort of 116 CRCs (57 males, 59 females) for chromosomal copy number aberrations (CNA) and found that CRC in females had significantly higher numbers of gains involving chromosome arms 1q21.2–q21.3, 4q13.2, 6p21.1 and 16p11.2 and copy number losses of chromosome arm 11q25 compared to males. Interestingly, a subset of male CRCs (46%) exhibited a “feminization” phenomenon in the form of gains of X chromosomes (or an arm of X) and/or losses of the Y chromosome. Feminization of cancer cells was significantly associated with microsatellite-stable CRCs (p-value 0.003) and wild-type BRAF gene status (p-value 0.009). No significant association with other clinicopathological parameters was identified including disease-free survival. In summary, our data show that some CNAs in CRC may be gender specific and that male cancers characterized by feminization may constitute a specific subset of CRCs that warrants further investigation. 相似文献