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71.
Biooxidation of ferrous iron by immobilized Acidithiobacillus ferrooxidans in poly(vinyl alcohol) cryogel carriers 总被引:4,自引:0,他引:4
PVA-cryogels entrapping about 109 cells of Acidithiobacillus ferrooxidans per ml of gel were prepared by freezing-thawing procedure, and the biooxidation of Fe2+ by immobilized cells was investigated in a 0.365 l packed-bed bioreactor. Fe2+ oxidation fits a plug-flow reaction model well. A maximum oxidation rate of 3.1 g Fe2+ l–1 h–1 was achieved at the dilution rate of 0.4 h–1 or higher, while no obvious precipitate was determined at this time. In addition, cell-immobilized PVA-cryogels packed in bioreactor maintained their oxidative ability for more than two months under non-sterile conditions.
Nomenclature:
C
A0 – Concentration of Fe2+ in feed stream (g l–1) C
A – Concentration of Fe2 + in outlet stream (g l– 1) D – Dilution rate of the packed-bed bioreactor (h–1) F – Volumetric flow rate of iron solution (l h–1) F
A0 – Mass flow rate of Fe2+ in the feed stream (g h–1) K – Kinetic constant (l l–1 h–1) r
A – Oxidation rate of Fe2+ (g l–1 h–1) V – Volume of packed-bed bioreactor (l) X
A – Conversion ratio of Fe2+ (%) 相似文献
72.
Packed-bed bioreactors containing activated carbon as support carrier were used to produce H2 anaerobically from a sucrose-limiting medium while acclimated sewage sludge was used as the H2 producer. The effects of bed porosity (b) and substrate loading rate on H2 fermentation were examined using packed beds with b of 70–90% being operated at hydraulic retention times (HRT) of 0.5–4 h. Higher b and lower HRT favored H2 production. With 20 g COD l–1 of sucrose in the feed, the optimal H2 production rate (7.4 l h–1 l–1) was obtained when the bed with b=90% was operated at HRT = 0.5 h. Flocculation of cells enhanced the retention of sludge for stable operations of the bioreactor at low HRTs. The gas products resulting from fermentative H2 production consisted of 30–40% H2 and 60–70% CO2. Butyric acid was the primary soluble product, followed by propionic acid and valeric acid. 相似文献
73.
Removal and destruction of high concentrations of gaseous toluene in a two-phase partitioning bioreactor by Alcaligenes xylosoxidans 总被引:1,自引:0,他引:1
A two-phase bioreactor consisting of hexadecane dispersed in an aqueous, cell-containing medium (organic fraction = 0.33) was used to trap toluene vapours from an air stream. The affinity for toluene by the solvent resulted in high efficiency of removal and transfer to the aqueous phase based on equilibrium transfer. The system was readily able to handle a loading capacity of 748 mg l–1 h–1 at a toluene degradation efficiency of greater than 98%. 相似文献
74.
Hematopoietic stem cells have applications in bone marrow transplantations for the treatment of hematopoietic disorders. When murine hematopoietic stem cells were cultured in 50 ml stirred bioreactors for 14 d, stem-cell-antigen-1 positive cells (hematopoietic primitive progenitor cells) and long-term culture-initiating cells (hematopoietic stem cells) grew by 5-fold and 4-fold, respectively. These results show the possibility of growing hematopoietic stem cells using a stirred bioreactor. 相似文献
75.
A comparative study of two modifications of enzymic reduction of ethyl N-{2-{4-[(2-oxo-cyclohexyl)methyl]phe- noxy}ethyl} carbamate (1), an insect juvenile hormone bioanalog, was performed using Saccharomyces cerevisiae in two bioreactors of different size, 250-ml shake-flask and 1-l fermenter. The two major products of this reduction were obtained in 45–49% (w/w) yields but with > 99% enantiomeric purity. Their absolute configurations were assigned as ethyl (1S,2S)-N-{2-{4-[(2-hydroxycyclohexyl)methyl]phenoxy}ethyl}carbamate (2a) and ethyl (1R,2S)-N-{2-{4-[(2-hydroxycyclohexyl)methyl]phenoxy}ethyl}carbamate (3a). 相似文献
76.
l-Lactic acid was produced from raw cassava starch, by simultaneous enzyme production, starch saccharification and fermentation in a circulating loop bioreactor with Aspergillus awamori and Lactococcus lactis spp. lactis immobilized in loofa sponge. A. awamori was immobilized directly in cylindrical loofa sponge while the L. lactis was immobilized in a loofa sponge alginate gel cube. In the loofa sponge alginate gel cube, the sponge serves as skeletal support for the gel with the cells. The alginate gel formed a hard outer layer covering the soft porous gel inside. By controlling the rate and frequency of broth circulation between the riser and downcomer columns, the riser could be maintained under aerobic condition while the downcomer was under anaerobic condition. Repeated fed-batch l-lactic acid production was performed for more than 400 h and the average lactic acid yield and productivity from raw cassava starch were 0.76 g lactic acid g–1 starch and 1.6 g lactic acid l–1 h–1, respectively. 相似文献
77.
Fan Z South C Lyford K Munsie J van Walsum P Lynd LR 《Bioprocess and biosystems engineering》2003,26(2):93-101
Conversion of paper sludge to ethanol was investigated with the objective of operating under conditions approaching those expected of an industrial process. Major components of the bleached Kraft sludge studied were glucan (62 wt.%, dry basis), xylan (11.5%), and minerals (17%). Complete recovery of glucose during compositional analysis required two acid hydrolysis treatments rather than one. To avoid the difficulty of mixing unreacted paper sludge, a semicontinuous solids-fed laboratory bioreactor system was developed. The system featured feeding at 12-h intervals, a residence time of 4 days, and cellulase loading of 15 to 20 FPU/g cellulose. Sludge was converted to ethanol using simultaneous saccharification and fermentation (SSF) featuring a -glucosidase-supplemented commercial cellulase preparation and glucose fermentation by Saccharomyces cerevisiea. SSF was carried out for a period of 4 months in a first-generation system, resulting in an average ethanol concentration of 35 g/L. However, steady state was not achieved and operational difficulties were encountered. These difficulties were avoided in a retrofitted design that was operated for two 1-month runs, achieving steady state with good material balance closure. Run 1 with the retrofitted reactor produced 50 g/L ethanol at a cellulose conversion of 74%. Run 2 produced 42 g/L ethanol at a conversion of 92%. For run 2, the ethanol yield was 0.466 g ethanol/g glucose equivalent fermented and >94% of the xylan fed to the reactor was solubilized to a mixture of xylan oligomers and xylose. 相似文献
78.
A general approach is described for the implementation of a networked multi-unit computer integrated control system. The use
of data acquisition hardware and graphical programming tools alleviates tedious programming and maintains potency and flexibility.
One application of the control system, the control of a mammalian cell perfusion culture based on a key nutrient glucose concentration,
was demonstrated. The control system offers customized user interface for all process control parameters and allows the flexibility
for continued improvement and implementation of new tailored functions. The temperature, pH, dissolved oxygen and glucose
level were accurately controlled.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
79.
S.J. Setford 《Biotechnology Techniques》1998,12(9):701-705
Viscosity regulation allowed the sedimentation of dextran to be increased from 1.89 to 2.89 g.h–1 within a novel centrifugal bioreactor. At an enzyme activity of 187 U, dextran pelleting was 1.66 mg g.h–1. U which was 50% greater than at an enzyme activity of 1344 U. Reactor productivity, at 1.5–2 g.h–1, was similar for both batch and semi-continuous trials. Rotor core design influenced productivity. © Rapid Science Ltd. 1998 相似文献
80.
Production, extraction and purificationof violacein: an antibiotic pigment producedby Chromobacterium violaceum 总被引:1,自引:0,他引:1
A procedure for the production, extraction, and purification of violacein was developed using Chromobacterium violaceum (CCT 3496) cultivated on cotton, in modified 1 litre Roux bottles. A surface tray bioreactor was built to perform these experiments. Violacein was extracted with commercial ethanol, and purified by filtration, Soxhlet extraction, crystallization and high performance liquid chromatography. The violacein was analysed and identified by proton and carbon-13 NMR spectroscopies, thermogravimetric analysis, mass spectrometry, UV-VIS spectroscopy and infrared spectroscopy. It was concluded that the product was highly purified violacein. 相似文献