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排序方式: 共有268条查询结果,搜索用时 46 毫秒
261.
Sangeetha K.Abhijit Roy Satish SinghBoeun Lee Prashant N. Kumta 《Materials Science and Engineering: B》2011,176(20):1703-1710
Coatings on yttrium doped magnesium (Mg4Y) alloy substrates were prepared using alginate hydrogels by dip coating method to improve the surface bioactive properties of the substrate. Furthermore, composite coatings containing nano-sized calcium phosphate corresponding to hydroxyapatite (HA) phase entrapped within alginate hydrogel were also synthesized on the Mg4Y substrates. Surface characteristics of these coated substrates have been investigated using FTIR-ATR, SEM and EDS. The results show that the coatings with alginate alone are not stable in vitro; however, incorporation of NanoCaPs slightly improves the stability of these coatings. In addition, these composite coatings showed cell attachments with fibronectin incorporation. These results indicate that alginate hydrogels have the potential to be used as bioactive coating materials for different biofunctional applications. 相似文献
262.
Sergey N. Kosourov Maria L. GhirardiMichael Seibert 《International Journal of Hydrogen Energy》2011,36(3):2044-2048
Photoproduction of H2 gas was examined in the Chlamydomonas reinhardtii tla1 strain, CC-4169, containing a truncated light-harvesting antenna, along with its parental CC-425 strain. Although enhanced photosynthetic performance of truncated antenna algae has been demonstrated previously (Polle et al. Planta 2003; 217:49-59), improved H2 photoproduction has yet to be reported. Preliminary experiments showed that sulfur-deprived, suspension cultures of the tla1 mutant could not establish anaerobiosis in a photobioreactor, and thus, could not photoproduce H2 gas under conditions typical for the sulfur-deprived wild-type cells (Kosourov et al. Biotech Bioeng 2002; 78:731-40). However, they did produce H2 gas when deprived of sulfur and phosphorus after immobilization within thin (∼300 μm) alginate films. These films were monitored for long-term H2 photoproduction activity under light intensities ranging from 19 to 350 μE m−2 s−1 PAR. Both the tla1 mutant and the CC-425 parental strain produced H2 gas for over 250 h under all light conditions tested. Relative to the parental strain, the CC-4169 mutant had lower maximum specific rates of H2 production at low and medium light intensities (19 and 184 μE m−2 s−1), but it exhibited a 4-times higher maximum specific rate at 285 μE m−2 s−1 and an 8.5-times higher rate at 350 μE m−2 s−1 when immobilized at approximately the same cell density as the parental strain. As a result, the CC-4169 strain accumulated almost 4-times more H2 than CC-425 at 285 μE m−2 s−1 and over 6-times more at 350 μE m−2 s−1 during 250-h experiments. These results are the first demonstration that truncating light-harvesting antennae in algal cells can increase the efficiency of H2 photoproduction in mass culture at high light intensity. 相似文献
263.
《Advanced Powder Technology》2014,25(5):1541-1546
Alginate microspheres were prepared by a water-in-oil emulsion solvent diffusion method. The alginate microspheres were post-cross-linked with Ca2+ ions. Influence of Ca2+ concentration on the characteristics and drug release behaviors of alginate microspheres was evaluated. Blue dextran was used as a water-soluble model drug. The non-cross-linked alginate microspheres were less than 100 μm in size and had a spherical shape. The cross-linked alginate microspheres were also spherical in shape with a rougher surface but their particle sizes were larger than 100 μm. The drug encapsulation efficiency of the non-cross-linked alginate microspheres was very high (82%). The drug encapsulation efficiency of alginate microspheres cross-linked with 5% and 10% Ca2+ concentrations were similar to the non-cross-linked microspheres. The in vitro drug releases of the cross-linked alginate microspheres showed prolong release profiles. The cumulative release of blue dextran decreased as the Ca2+ concentration increased. Thus, Ca2+-post-cross-linked alginate microspheres show possibility for use as controlled-release drug carriers. 相似文献
264.
Jong-Whan Rhim 《LWT》2004,37(3):323-330
Properties of sodium alginate films were modified using two different methods of CaCl2 treatment, i.e. the direct addition of CaCl2 into film making solution (mixing films) and the immersion of alginate films into CaCl2 solutions (immersion films), and their treatment effects on tensile strength (TS), percentage elongation at break (E), water vapor permeability (WVP), and water solubility (WS) of the films were investigated. TS and E of the mixing films were not changed considerably, but those of the immersion films changed considerably with significant (P<0.05) increase in TS and decrease in E. WVP of the immersion films decreased significantly (P<0.05), but that of the mixing films did not decreased. Water resistance measured by WS was not improved with the mixing films, but the alginate films became water resistant when they treated by immersing in higher than 2 g/100 ml CaCl2 solutions. Water adsorption by the films also decreased in the immersion films. Swelling ratio (SR) of the immersion film decreased with temperature without affecting WS of the films. 相似文献
265.
用陶瓷颗粒吸附糖化酶后,再以不同配比的聚乙烯醇-海藻酸钠复合溶胶覆膜,分别对固定化条件、米氏常数、酶活残留率进行了研究,结果表明:陶瓷颗粒聚乙烯醇复合溶胶固定化糖化酶的条件是:聚乙烯醇:海藻酸钠配比为6∶4,溶胶浓度为7%,固化时间为120min。米氏常数为60.17mg/mL,酶活残留率为78%;陶瓷颗粒覆海藻酸钠复合溶胶固定化糖化酶的条件是:海藻酸钠∶聚乙烯醇配比是8∶2,溶胶浓度为1.5%,固化时间为90min。米氏常数为35.5mg/mL,酶活残留率为38%。 相似文献
266.
Ekambaram Nakkeeran Rangaswamy Subramanian Sukumaran Umesh-Kumar 《Journal of Bioscience and Bioengineering》2010,109(2):101-106
Purification of polygalacturonase (PG) from the cultures of Aspergillus carbonarius obtained by acetate buffer extraction after solid-state fermentation was attempted by integrated membrane process and alginate affinity precipitation. The carbohydrates were completely eliminated (98%–99%) with a PG recovery of 72%–80% during integrated membrane process, which would otherwise interfere with the purification process and lead to enzyme loss. However, specific activity of PG did not improve (1.19–1.21 fold) due to the presence of other similar molecular mass proteins. Under optimum conditions of affinity precipitation, the specific activity of PG enhanced to 2450 U/mg (4 fold) with almost complete elimination of carbohydrates and colour compounds resulting in a PG recovery of 61%. PG purity obtained with ultrafiltration (UF) was comparable with the conventional dialysis during desalting eluted PG, besides UF rendered a concentrated PG. The enzyme purity stated was as descend by SDS–PAGE. The results suggested suitability of affinity precipitation for PG purification from solid-state cultures and the potential of UF as a single step process for handling eluted PG. 相似文献
267.
《Journal of food engineering》2013,118(3):312-325
To ensure sterility of a solid–liquid mixture processed in continuous-flow ohmic systems, the slowest-heating solid particle needs to receive sufficient heat treatment at the outlet of the holding section. We describe herein, the development of a mathematical model for solid–liquid mixtures in a commercial ohmic heater with electric field oriented perpendicular to the flow. The fastest moving particle velocity was identified using over 299 particles and a radio-frequency identification technique, and used as an input to the model for the worst-case heating scenario. Thermal verification was conducted by comparing predicted and measured fluid temperatures at heater and hold tube outlets; the model showed good agreement between calculated and experimental fluid temperatures (P > 0.05) with a maximum error of 0.4 °C. The model predicted a hold tube length of 15.85 m at 134.0 °C process temperature to achieve a target lethal effect at the cold spot of the slowest-heating particle. Using this length of hold tube, microbiological tests were conducted using at least 299 chicken/alginate particles inoculated with Clostridium sporogenes spores per run. These tests showed the absence of viable microorganisms at the target treatment and positive growth when temperatures were below target, thereby verifying model predictions. 相似文献
268.