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61.
62.
《Analytical letters》2012,45(10):825-836
Abstract A microbial electrode has been developed that uses im -mobilized Nocardia erythropolis for the determination of cholesterol. The relationship between the measuring signal and the cholesterol concentration was linear up from T5-130 um, with a reproducibility of 2 – 7 %. To shorten the measuring time the derivative of the current – time curve was monitored. The resulting response time was 35 – 70 sec. The sensor was usuable for more than 4 weeks. 相似文献
63.
64.
High pressure processing (HPP) has been shown to reduce microbial concentration in foods. The mechanisms of microbial inactivation by HPP have been associated with damage to cell membranes. The real-time response of bacteria to HPP was measured to elucidate the mechanisms of inactivation, which can aid in designing more effective processes. Different pressure cycling conditions were used to expose Enterobacter aerogenes cells to HPP. Propidium iodide (PI) was used as a probe, which fluoresces after penetrating cells with damaged membranes and binding with nucleic acids. A HPP vessel with sapphire windows was used for measuring fluorescence in situ. Membrane damage was detected during pressurization and hold time, but not during depressurization. The drop in fluorescence was larger than expected after pressure cycles at higher pressure and longer times. This indicated possible reversible disassociation of ribosomes resulting in additional binding of PI to exposed RNA under pressure and its release after depressurization. 相似文献
65.
The investigation of the combination of enzymatic and chemical synthetic processes for the production of useful compounds
has been carried out. This review focuses on the enzymatic transformation of chemically synthesized 3-chloroalanine into useful
amino acids. 相似文献
66.
T. Coviello W. Burchard M. Dentini V. Crescenzi V. J. Morris 《Journal of Polymer Science.Polymer Physics》1995,33(12):1833-1846
Three polysaccharides, Rhizobium leguminosarum 8002 EPS(I), Rhizobium trifolii TA1-EPS (II), Rhizobium leguminosarum 127K87 EPS (III), produced by bacteria of Rhizobium genus have been investigated by static and dynamic light scattering combined with chirooptical measurements. All three polymers have the same backbone but differ in the length of the side chains and in the content of minor substituents. An isothermal conformational transition coil → helix was observed with I and II by adding salt (NaCl). The molecular parameters of the polysaccharides in the ordered state were determined by light-scattering data. Increasing the ionic strength a shrinking of the helix was observed accompanied by a corresponding decrease in the radius of gyration. An extraordinary chain stiffness in terms of Kuhn segment lengths was found in both cases, similar to that already observed for other microbial polysaccharides. In the case of III no disorder → order transition was induced by the salt, and the scattering behavior corresponds to that of a rather flexible polymer with a characteristic ratio C∞ = 24. The incapability of III to form a helical structure is attributed to the effect of the very long side chain. The analysis of the time correlation functions revealed typical flexible chain behavior for all three polysaccharides. This behavior for the two ordered polymers is in agreement with a recent theory by Maggs and is due to bending modes of the rods. ©1995 John Wiley & Sons, Inc. 相似文献
67.
The adhesion of filamentous microbial cells such as Trichoderma reesei was studied by using carriers covered with polymers which were prepared by the radiation polymerization of ionic monomers. The weight of the cells adhering to the carriers increased with increasing cationic monomer content, indicating that the surface of the polymers prepared from cationic and hydrophobic monomers is suitable for the adhesion of the cells. The production of cellulase in the cells adhered to polymers from cationic monomers was higher than that in cells adhered to polymers prepared from anionic monomers. The growth of the cells adhered to the surfaces of the polymers was affected by the hydrophilicity of the polymers. 相似文献
68.
Olaf K. Horbaczuk Artur J
wik Jarosaw Wyrwisz Joanna Marchewka Agnieszka Wierzbicka 《Molecules (Basel, Switzerland)》2021,26(11)
The aim of this study was to evaluate the effect of the packaging system type on the physical characteristics and microbial changes in ostrich meat during refrigerated storage. The applied packaging systems were vacuum packaging (VP) and modified atmosphere packaging (MAP) using two combinations of gases: MAP1 (40% O2/40% CO2/20% N2) and MAP2 (60% O2/30% CO2/10% N2). Eight meat samples were obtained in three replicates for all parameters, except for pH, for which six replicates were obtained from the M. ilifibularis (IF) muscle, and were stored in a refrigerator at 2 °C and analyzed at 0, 4, 8, 12 and 16 days for the effect of packaging methods on physical meat quality. The initial pH (5.99) decreased at the end of the storage time for MAP1 to 5.81, whereas VP was stable from day 0 to 12 and increased up to 6.08 on day 16. Regarding meat color, the L* value increased during storage for MAP1 and MAP2 from 36.99 to 40.75 and 41.60, respectively, whereas it declined for VP to 34.22. The same tendencies were reported for redness (a*) and yellowness (b*). Drip loss was the lowest in MAP1 and highest in VP. The lowest total viable bacteria counts were identified in VP, as compared to MAP1 and MAP2. 相似文献
69.
Joseph Bagi Suleiman Mahaneem Mohamed Ainul Bahiyah Abu Bakar Victor Udo Nna Zaida Zakaria Zaidatul Akmal Othman Abdulqudus Bola Aroyehun 《Molecules (Basel, Switzerland)》2021,26(16)
The aim of the study was to determine the chemical profile, antioxidant properties and antimicrobial activities of Heterotrigona itama bee bread from Malaysia. The pH, presence of phytochemicals, antioxidant properties, total phenolic content (TPC) and total flavonoid content (TFC), as well as antimicrobial activities, were assessed. Results revealed a decrease in the pH of bee bread water extract (BBW) relative to bee bread ethanolic extract (BBE) and bee bread hot water extract (BBH). Further, alkaloids, flavonoids, phenols, tannins, saponins, terpenoids, resins, glycosides and xanthoproteins were detected in BBW, BBH and BBE. Also, significant decreases in TPC, TFC, DPPH activity and FRAP were detected in BBW relative to BBH and BBE. We detected phenolic acids such as gallic acid, caffeic acid, trans-ferulic acid, trans 3-hydroxycinnamic acid and 2-hydroxycinnamic acid, and flavonoids such as quercetin, kaempferol, apigenin and mangiferin in BBE using high-performance liquid chromatography analysis. The strongest antimicrobial activity was observed in Klebsilla pneumonia (MIC50 1.914 µg/mL), followed by E. coli (MIC50 1.923 µg/mL), Shigella (MIC50 1.813 µg/mL) and Salmonella typhi (MIC50 1.617 µg/mL). Bee bread samples possess antioxidant and antimicrobial properties. Bee bread contains phenolic acids and flavonoids, and could be beneficial in the management and treatment of metabolic diseases. 相似文献
70.
Songul Ulag Elif Ilhan Ramazan Demirhan Ali Sahin Betul Karademir Yilmaz Burak Aksu Mustafa Sengor Denisa Ficai Aurel Mihail Titu Anton Ficai Oguzhan Gunduz 《Molecules (Basel, Switzerland)》2021,26(9)
In this research, polyvinyl-alcohol (PVA)/gelatin (GEL)/propolis (Ps) biocompatible nanofiber patches were fabricated via electrospinning technique. The controlled release of Propolis, surface wettability behaviors, antimicrobial activities against the S. aureus and P. aeruginosa, and biocompatibility properties with the mesenchymal stem cells (MSCs) were investigated in detail. By adding 0.5, 1, and 3 wt.% GEL into the 13 wt.% PVA, the morphological and mechanical results suggested that 13 wt.% PVA/0.5 wt.% GEL patch can be an ideal matrix for 3 and 5 wt.% propolis addition. Morphological results revealed that the diameters of the electrospun nanofiber patches were increased with GEL (from 290 nm to 400 nm) and Ps addition and crosslinking process cause the formation of thicker nanofibers. The tensile strength and elongation at break enhancement were also determined for 13 wt.% PVA/0.5 wt.% GEL/3 wt.% Ps patch. Propolis was released quickly in the first hour and arrived at a plateau. Cell culture and contact angle results confirmed that the 3 wt.% addition of propolis reinforced mesenchymal stem cell proliferation and wettability properties of the patches. The antimicrobial activity demonstrated that propolis loaded patches had antibacterial activity against the S. aureus, but for P. aeruginosa, more studies should be performed. 相似文献