全文获取类型
收费全文 | 144篇 |
免费 | 13篇 |
专业分类
化学工业 | 101篇 |
金属工艺 | 2篇 |
轻工业 | 10篇 |
无线电 | 4篇 |
一般工业技术 | 21篇 |
冶金工业 | 13篇 |
自动化技术 | 6篇 |
出版年
2023年 | 9篇 |
2022年 | 25篇 |
2021年 | 40篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 5篇 |
2017年 | 6篇 |
2016年 | 2篇 |
2015年 | 10篇 |
2014年 | 2篇 |
2013年 | 11篇 |
2012年 | 2篇 |
2011年 | 7篇 |
2010年 | 6篇 |
2009年 | 2篇 |
2007年 | 1篇 |
2006年 | 1篇 |
2004年 | 1篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1992年 | 1篇 |
1976年 | 2篇 |
1966年 | 1篇 |
排序方式: 共有157条查询结果,搜索用时 15 毫秒
61.
Patrycja Gorzelak Gracjana Klein Satish Raina 《International journal of molecular sciences》2021,22(10)
To identify the physiological factors that limit the growth of Escherichia coli K-12 strains synthesizing minimal lipopolysaccharide (LPS), we describe the first construction of strains devoid of the entire waa locus and concomitantly lacking all three acyltransferases (LpxL/LpxM/LpxP), synthesizing minimal lipid IVA derivatives with a restricted ability to grow at around 21 °C. Suppressors restoring growth up to 37 °C of Δ(gmhD-waaA) identified two independent single-amino-acid substitutions—P50S and R310S—in the LPS flippase MsbA. Interestingly, the cardiolipin synthase-encoding gene clsA was found to be essential for the growth of ΔlpxLMP, ΔlpxL, ΔwaaA, and Δ(gmhD-waaA) bacteria, with a conditional lethal phenotype of Δ(clsA lpxM), which could be overcome by suppressor mutations in MsbA. Suppressor mutations basS A20D or basR G53V, causing a constitutive incorporation of phosphoethanolamine (P-EtN) in the lipid A, could abolish the Ca++ sensitivity of Δ(waaC eptB), thereby compensating for P-EtN absence on the second Kdo. A single-amino-acid OppA S273G substitution is shown to overcome the synthetic lethality of Δ(waaC surA) bacteria, consistent with the chaperone-like function of the OppA oligopeptide-binding protein. Furthermore, overexpression of GcvB sRNA was found to repress the accumulation of LpxC and suppress the lethality of LapAB absence. Thus, this study identifies new and limiting factors in regulating LPS biosynthesis. 相似文献
62.
Patrycja Kopytko Katarzyna Piotrowska Joanna Janisiak Maciej Tarnowski 《International journal of molecular sciences》2021,22(6)
Garcinol extracted from Garcinia indica fruit peel and leaves is a polyisoprenylated benzophenone. In traditional medicine it was used for its antioxidant and anti-inflammatory properties. Several studies have shown anti-cancer properties of garcinol in cancer cell lines and experimental animal models. Garcinol action in cancer cells is based on its antioxidant and anti-inflammatory properties, but also on its potency to inhibit histone acetyltransferases (HATs). Recent studies indicate that garcinol may also deregulate expression of miRNAs involved in tumour development and progression. This paper focuses on the latest research concerning garcinol as a HAT inhibitor and miRNA deregulator in the development and progression of various cancers. Garcinol may be considered as a candidate for next generation epigenetic drugs, but further studies are needed to establish the precise toxicity, dosages, routes of administration, and safety for patients. 相似文献
63.
1. The everted-sac technique has been used to study the time-dependent effect of low-calcium diet on calcium active transport along rat small intestine. 2. In animals maintained on standard diet active translocation of calcium was limited to proximal 10 cm of the intestine. 3. In response to calcium restriction, calcium transport in duodenum was highly stimulated after 3 days, then gradually declined and after 28 days almost disappeared. In proximal jejunum it was the highest between 7 and 21 days. In distal ileum, the transport appeared after 3 days and increased progressively until 21 days, but markedly decreased at the 28-th day. The normal pattern of calcium transport was reestablished on refeeding the animals with standard diet. 相似文献
64.
Magdalena Wypij Patrycja Golinska Hanna Dahm Mahendra Rai 《IET nanobiotechnology / IET》2017,11(3):336
In this study, silver nanoparticles (AgNPs) were biosynthesised by using acidophilic actinobacterial SH11 strain isolated from pine forest soil. Isolate SH11 was identified based on 16S rRNA gene sequence to Streptomyces kasugaensis M338‐M1T and S. celluloflavus NRRL B‐2493T (99.8% similarity, both). Biosynthesised AgNPs were analysed by UV–visible spectroscopy, which revealed specific peak at λ = 420 nm. Transmission electron microscopy analyses showed polydispersed, spherical nanoparticles with a mean size of 13.2 nm, while Fourier transform infrared spectroscopy confirmed the presence of proteins as the capping agents over the surface of AgNPs. The zeta potential was found to be −16.6 mV, which indicated stability of AgNPs. The antibacterial activity of AgNPs from SH11 strain against gram‐positive (Staphylococcus aureus and Bacillus subtilis) and gram‐negative (Escherichia coli) bacteria was estimated using disc diffusion, minimum inhibitory concentration and live/dead analyses. The AgNPs showed the maximum antimicrobial activity against E. coli, followed by B. subtilis and S. aureus. Further, the synergistic effect of AgNPs in combination with commercial antibiotics (kanamycin, ampicillin, tetracycline) was also evaluated against bacterial isolates. The antimicrobial efficacy of antibiotics was found to be enhanced in the presence of AgNPs.Inspec keywords: antibacterial activity, silver, nanoparticles, electrokinetic effects, Fourier transform infrared spectra, microorganisms, nanofabricationOther keywords: actinobacterial mediated synthesis, silver nanoparticles, pathogenic bacteria, biosynthesis, acidophilic actinobacterial SH11 strain, pine forest soil, 16S rRNA gene sequence, Streptomyces kasugaensis M338‐M1T, S. celluloflavus NRRL B‐2493T, UV–visible spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, zeta potential, gram positive bacteria, Staphylococcus aureus, Bacillus subtilis, gram negative bacteria, Escherichia coli, disc diffusion, wavelength 420 nm, Ag 相似文献
65.
Amelia C. Y. Liu Timothy J. Davis Toon Coenen Sangeetha Hari Lenard M. Voortman Zhou Xu Gangcheng Yuan Patrycja M. Ballard Alison M. Funston Joanne Etheridge 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(33):2207747
The waveguide modes in chemically-grown silver nanowires on silicon nitride substrates are observed using spectrally- and spatially-resolved cathodoluminescence (CL) excited by high-energy electrons in a scanning electron microscope. The presence of a long-range, travelling surface plasmon mode modulates the coupling efficiency of the incident electron energy into the nanowires, which is observed as oscillations in the measured CL with the point of excitation by the focused electron beam. The experimental data are modeled using the theory of surface plasmon polariton modes in cylindrical metal waveguides, enabling the complex mode wavenumbers and excitation strength of the long-range surface plasmon mode to be extracted. The experiments yield insight into the energy transfer mechanisms between fast electrons and coherent oscillations in surface charge density in metal nanowires and the relative amplitudes of the radiative processes excited in the wire by the electron. 相似文献
66.
Patrycja Juchniewicz Ewa Piotrowska Anna Kloska Magdalena Podlacha Jagoda Mantej Grzegorz Wgrzyn Stefan Tukaj Joanna Jakbkiewicz-Banecka 《International journal of molecular sciences》2021,22(9)
Through the use of new genomic and metabolomic technologies, our comprehension of the molecular and biochemical etiologies of genetic disorders is rapidly expanding, and so are insights into their varying phenotypes. Dosage compensation (lyonization) is an epigenetic mechanism that balances the expression of genes on heteromorphic sex chromosomes. Many studies in the literature have suggested a profound influence of this phenomenon on the manifestation of X-linked disorders in females. In this review, we summarize the clinical and genetic findings in female heterozygotic carriers of a pathogenic variant in one of ten selected X-linked genes whose defects result in metabolic disorders. 相似文献
67.
Konrad Szustakiewicz Marcin Wodarczyk Magorzata Gaziska Karolina Rudnicka Przemysaw Pociski Patrycja Szymczyk-Zikowska Grzegorz Zikowski Monika Biernat Katarzyna Sieja Micha Grzymajo Piotr J
wiak Sylwia Michlewska Andrzej W. Trochimczuk 《International journal of molecular sciences》2021,22(7)
In this research, we prepared foam scaffolds based on poly(l-lactide) (PLLA) and apatite whiskers (HAP) using thermally induced phase separation technique supported by the salt leaching process (TIPS-SL). Using sodium chloride having a size of (a) 150–315 μm, (b) 315–400 μm, and (c) 500–600 μm, three types of foams with different pore sizes have been obtained. Internal structure of the obtained materials has been investigated using SEM as well as μCT. The materials have been studied by means of porosity, density, and compression tests. As the most promising, the composite prepared with salt size of 500–600 μm was prepared also with the l-lysine modified apatite. The osteoblast hFOB 1.19 cell response for the scaffolds was also investigated by means of cell viability, proliferation, adhesion/penetration, and biomineralization. Direct contact cytotoxicity assay showed the cytocompatibility of the scaffolds. All types of foam scaffolds containing HAP whiskers, regardless the pore size or l-lysine modification induced significant stimulatory effect on the cal-cium deposits formation in osteoblasts. The PLLA/HAP scaffolds modified with l-lysine stimulated hFOB 1.19 osteoblasts proliferation. Compared to the scaffolds with smaller pores (150–315 µm and 315–400 µm), the PLLA/HAP foams with large pores (500–600 µm) promoted more effective ad-hesion of osteoblasts to the surface of the biomaterial. 相似文献
68.
Kowalska P Cheeseman JR Razmkhah K Green B Nafie LA Rodger A 《Analytical chemistry》2012,84(3):1394-1401
This paper reports the development of the new technique of Raman linear difference (RLD) spectroscopy and its application to small molecules: anthracene and nucleotides adenosine-5'-monophosphate, thymidine-5'-monophosphate, guanosine-5'-monophosphate, and cytidine-5'-monophosphate. In this work we also present a new alignment method for Raman spectroscopy where stretched polyethylene films are used as the matrix. Raman spectra using light polarized along the orientation direction and perpendicular to it are reported. The polyethylene (PE) film spectra are consistent with powder samples and films deposited on quartz. RLD spectra determined from the difference of the parallel and perpendicular polarized light Raman spectra are also reported. The equations describing RLD are derived, and RLD spectra of anthracene and thymidine are calculated from these equations using Density Functional Theory and assuming perfect orientation of the samples. Because of the wealth of spectroscopic information in the vibrational spectra of biomolecules together with our ability to calculate spectra as a function of orientation, we conclude that RLD has the potential to provide structural information for biological samples that currently cannot be extracted from any other method. 相似文献
69.
Agnieszka Maria Jastrzębska Patrycja Kurtycz Andrzej Roman Olszyna Joanna Jureczko Antoni Ryszard Kunicki 《International Journal of Applied Ceramic Technology》2014,11(4):738-744
The present article presents first comparative study on three different dry solgel methods of producing new alumina‐based dark violet, light pink ceramic nanopigments as well as ruby‐red ceramic nanopigment — an alternative to the Purple of Cassius. Gold nanoparticles are built directly on a carrier of an aluminum oxide nanopowder, which finally yields Al2O3/Au nanopowders possessing colors ranging from light pink to light violet as well as ruby‐red. 相似文献
70.
Conducting composites prepared by the reduction of silver ions with poly(p‐phenylenediamine) 下载免费PDF全文
Przemysław Magdziarz Patrycja Bober Miroslava Trchová Zuzana Morávková Michal Bláha Jan Prokeš Jaroslav Stejskal 《Polymer International》2015,64(4):496-504
Poly(p‐phenylenediamine) (PPDA) and also its ladder‐like analogue were prepared by oxidation of p‐phenylenediamine with ammonium peroxydisulfate in an aqueous solution of 0.4 mol L?1 hydrochloric acid and converted to PPDA bases. These were used as reductants of silver nitrate to silver nanoparticles in 1 mol L?1 methanesulfonic acid or in water at various mole ratios of silver nitrate to p‐phenylenediamine units from 0 to 1.8. The original conductivity of the PPDA, 10?12 S cm?1, increased to the order of 100 S cm?1 for the PPDA–silver composites containing 27–40 wt% (i.e. 4.5–6.6 vol%) silver. Fourier transform infrared spectra indicated a practically unchanged molecular structure of PPDA in the composites. In contrast, Raman spectroscopy showed the existence of regions with unchanged molecular structure of PPDA as well as the presence of regions containing silver particles and oxidized PPDA moieties. © 2014 Society of Chemical Industry 相似文献