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81.
Thomsen M Görtz A Nägerl UV Kubein-Meesenburg D Görtz W Fanghänel J Nägerl H 《Journal of biomechanical engineering》2000,122(4):416-422
The paper presents a novel method for recording amplitude and phase of 6D-vibrations of a spatial pendulum over a wide frequency range (10 Hz up to 20 kHz). The six degrees of freedom of the pendulum mass were monitored by three electrodynamic stereo pickups. At rest, the tips of the needles and the pendulum's center of mass defined the reference system with respect to which the oscillations of the mass were recorded in terms of their amplitudes and phases. Its small dimensions, constant transfer characteristics, linearity, high dynamics, and virtual lack of reaction onto the moving system over the entire frequency range provided the advantages of the measuring system. This method was used to analyze the spatial 6D-vibrations of the head of a cemented femoral hip endoprosthesis when the femur was stimulated to bending vibrations. The head of the prosthesis carried out axial rotational vibrations at every frequency used to stimulate the femur. The amplitudes of the axial rotations of the cortical bone were small in comparison to the ones of the prosthesis head, indicating that axial rotational vibrations following femur bending vibrations mainly stressed the spongiosa and the cement layer. This was observed over the entire frequency range, including at the low frequencies relevant for gait. Over the low-frequency range, as well as at some of the higher resonance frequencies, stationary instantaneous helical axes characterized the vibrations. The measurements suggest the mechanism that the interface "implant-bone" may already be stressed by axial torsional loads when the femur is loaded by bending impacts that are known to occur during walking. 相似文献
82.
Summary When using shear activation of Clostridium acetobutylicum by pumping the cells through capillaries, the cell growth, glucose consumption and product formation rates are considerably increased. Shear-activated continuous cell culture can be used as an inoculum with a welldefined fermentation activity for batch cultures. Different runs of such batch cultivation yield well-reproducible results which could not be obtained from inocula of other cultures or even of heat-shocked spores. The cells can attain a growth rate higher than 1.6 h-1.The shear-activated continous culture growth is affected already at a butanol concentration lower than 1.6 g/l-1. 相似文献
83.
Penicillin V and/or G were extracted from fermentation broth by Amberlite LA-2 in n-butylacetate at pH 5 in a laboratory centrifugal extractor, Type SA 01 of Westfalia, up to an overall phase throughput rate of 30 L/h, in a bench-scale four-stage extraction system, consisting of Type TA 1 of Westfalia, up to an overall phase throughput rate of 110 L/h, and in a pilot-plant three-stage extraction unit, consisting of Type TA 7 extractors of Westfalia, up to a phase throughput rate of 990 L/h with very high degrees of extraction (up to 99%). The reextraction from the ion-pair complex, which contained organic solvent, was performed by phosphate, borate, or carbonate buffer at pH 7.5-8.5 in all three extractor systems with degrees of extraction up to 98%, but at considerably lower overall phase throughput rates than those of the extraction, since no satisfactory phase separation is possible at higher throughput rates. 相似文献
84.
Fluiddynamic characterization of airlift tower loop bioreactors with and without motionless mixtures
In a 60 l airlift tower reactor with outer loop fluiddynamical measurements were carried out in presence of three motionless mixer modules (Type SMV, Sulzer) in water, 0.6%, 0.9% and 1.2% CMC solutions. The global mixing properties were determined in the liquid and gas phases by tracers. Detailed local measurements revealed differences of local flow patterns and mixing properties in the unhindered riser and in the immediate wake of the mixer module. The local liquid velocities were measured by the pseudorandom heat pulse technique. The local bubble velocities were determined by the ultrasound Doppler technique. The dependence of liquid velocity, gas velocity and gas holdup on the superficial gas velocity were determined. The radial profiles of the mean liquid velocities and their standard deviations were evaluated in water and CMC solutions upstream and downstream of the motionless mixer modules. The radial profiles of the mean large-bubble velocities and mean small-bubble velocities and their standard deviations were determined as well. The influence of the presence of the motionless mixers in the riser on these properties was evaluated.List of Symbols
Bo
L
w
L
L/D
L
liquid Bo number
-
Bo
G
w
G
L/D
G
,gas Bo number
-
c
tracer concentration
-
CMC
carboxymelthylcellulose
-
D
G
gas dispersion coefficient
-
D
1
local liquid dispersion coefficient
-
D
L
liquid dispersion coefficient
-
D
r
riser diameter
-
d
distance between transmitter and detector of the heat pulse probe
-
E
G
gas holdup
-
HBV
horizontal bubble velocity
-
HLBV
horizontal large-bubble velocity
-
HSBV
horizontal small-bubble velocity
-
L
length of the column
-
l
relative distance of the detector position from the tracer injection with respect to L
-
LBV
large-bubble velocity
-
n
number of circulations
-
OHBV
overall horizontal bubble velocity
-
OVBV
overall vertical bubble velocity
-
P
power input
-
Pe
1
w
1d/D1, local liquid Peclet number
-
SBV
small-bubble-velocity
-
V
L
liquid volume
-
VBV
vertical bubble velocity
-
VLBV
vertical large-bubble velocity
-
VSBV
vertical small-bubble velocity
-
w
G
gas velocity
-
w
1
local liquid velocity
-
w
L
liquid velocity
-
w
SG
superficial gas velocity
-
w
SL
superficial liquid velocity
-
mean residence time of the liquid in the riser
H.M.R. thank the Verband der Chemischen Industrie for a Fund der Chemie scholarship 相似文献
85.
H. H. Lischke L. Brandes Xiaoan Wu K. Schügerl 《Bioprocess and biosystems engineering》1993,9(4):155-157
The influence of the acetate addeed to the M9 minimal medium and to the Luria-Bertani medium without and with glucose supplement on the growth of recombinant Escherichia coli J103 with three different types of multicopy plasmids and on the production of the fusion protein SpA :: EcoRI were investigated in shake flasks without and with induction of the gene expression by a temperature shift from 30 °C to 42 °C. At the beginning of the induction of gene expression concentrated LB-medium was added to the shake flask. Without this supplement of M9 medium no gene expression occurred.List of Symbols
LB
Luria Bertani cultivation medium (Table 2)
-
M9
cultivation medium (Table 1)
-
P
enzym activity [U ml–1]
-
te]TCC
total cell count [106 cells ml–1]
-
specific growth rate [h-1] 相似文献
86.
Summary
Chaetomium cellulolyticum (ATCC 32319) was cultivated on glucose, Avicel and/or Sigmacell in a 20-1 stirred tank batch reactor. The substrate (cellulose) concentration, the cell mass concentration (through protein and/or nitrogen content), reducing sugar concentration, the enzyme activity, the alkali consumption rate, the dissolved O2 and CO2 concentrations in the outlet gas were measured. The specific growth rate, the substrate yield coefficient, cell productivity, the oxygen consumption rate, the CO2 production rate and the volumetric mass transfer coefficient were determined. At the beginning of the growth phase the oxygen utilization rate exhibits a sharp maximum. This maximum could be used to start process control. Because of the long lag phase periodic batch operation is recommended.Symbols CP
cell protein concentration (g l–1)
- FPA
FP enzyme activity (IU l–1)
- GP
dissolved protein concentration (g l–1)
- IU
international unit of enzyme activity
- kLa
volumetric mass tranfer coefficient (h–1)
- LG
alkali (1 n NaOH) consumption (ml)
- LGX
specific alkali consumption rate per cell mass (ml g–1 h–1)
- P
cell mass productivity (g l–1 h–1)
-
specific oxygen consumption rate per cell mass (g g–1 h–1)
- Q
aeration rate (volumetric gas flow rate per volume of medium, vvm) (min–1)
- N
impeller speed (revolution per minute, rpm) (min–1)
- S
substrate concentration (g l–1)
- S0
S at tF=0 (g l–1)
- S0
S in feed (g l–1)
- SR
acid consumption (ml)
- TDW
total dry weight (g l–1)
- T
temperature (° C)
- tF
cultivation time (h)
- U
substrate conversion
- X
cell mass concentration (g l–1)
- YX/S
vield coefficient
-
specific growth rate (h–1)
- m
maximum specific growth rate (h–1) 相似文献
87.
I. M. Mishra S. A. El-Temtamy K. Schügerl 《Applied microbiology and biotechnology》1982,16(4):197-203
Summary Baker's yeast was aerobically grown in gaseous fluidized beds in the form of solid particles. Air was used as the fluidizing fluid and as a source of oxygen, while the concentrated nutrient solution was sprayed at the top of the bed. Five glucose concentrations 125, 160, 200, 250 und 350 gl–1 were used. A maximum in the growth rate and in the yield coefficient occurred at 250 and 200 g l–1, respectively. The calculated growth rates are one order of magnitude less than the growth rates in submerged cultures, but the maintenance energy coefficient is the same in both systems. Alcohol ppm level in the exhaust gases increased with increasing glucose concentration in the nutrient solution. Oscillations in the alcohol production indicated product inhibition of the cell growth under high glucose concentrations in the nutrient feed solution. 相似文献
88.
Summary
Hansenula polymorpha was cultured for long periods in 254 cm high single and three-stage countercurrent tower loop reactors 20 cm in diameter
using ethanol as a substrate in the absence and presence of antifoam agents (Desmophen 3600 and/or soy oil). In the absence
of antifoam agents in the three-stage column, much higher volumetric mass transfer coefficients were attained than in the
corresponding single-stage column. The cell productivity in the former, however, was only slightly higher than in the single-stage
column due to considerable enrichment of the cells in the foam and nonuniform cell concentration distribution in the three-stage
column. In the presence of antifoam agents the three-stage column has a higher cell productivity, OTR, kL a and a lower specific energy requirement with regard to the absorbed oxygen and/or produced cell mass than the single stage
column. The reactor performance is especially high if the bubbling layer height is reduced to 20 cm. Soy oil has considerably
less foam eliminating property than Desmophen. Since the soy oil is metabolized by the yeast, large amounts are needed to
operate these reactors. 相似文献
89.
R. Luttmann M. Thoma H. Buchholz W. Scheiding K. Schügerl 《Applied microbiology and biotechnology》1981,13(2):90-95
Summary Cultivation of Hansenula polymorpha with substrate ethanol in a bench-scale tower loop reactor was simulated by means of a distributed parameter model with regard
to the dissolved oxygen and substrate in the medium, oxygen and CO2 in the gas phase, and a lumped parameter model with regard to the cell mass. Space and time independence of the substrate
and oxygen limiting constants of the Monod model, KS and KO, was assumed. Time variations of the yield coefficients, YX/S and YX/O, were allowed for. 相似文献
90.
I. Adler H. Buchholz J. Voigt R. Wittler K. Schügerl 《Applied microbiology and biotechnology》1980,9(4):249-260
Summary Volumetric mass transfer coefficients (kLa) were measured by a steady state method in a twin bubble column to characterize the coalescence behaviour of the medium. Employing Hansenula polymorpha cultivation broths, kLa values were compared with those measured in model media in the presence and absence of antifoam agents. The ratio of the volumetric mass transfer coefficient in the system investigated to that in water,
, was employed to characterize the cultivation medium.Symbols a
Specific gas/liquid interfacial area with regard to the liquid volume in reactor
- de
Dynamical equilibrium bubble diameter
- dH
Perforated plate hole diameter
- dp
Primary bubble diameter
- dS
Sauter bubble diameter
- Fv
Liquid feed rate
- H
Bubbling layer height
- kL
Gas/liquid mass transfer coefficient
- kLa
Volumetric mass transfer coefficient
- m
kLa/(kLa)r coalescence index
- mcorr
Corrected coalescence index [Eq. (3)]
- OTR
Oxygen transfer rate
- PO
Dissolved O2-partial pressure in BS2
- P1
Dissolved O2-partial pressure in BS1
- PO
PO/PS relative oxygen saturation in BS2
- P1
P1/PS relative oxygen saturation in BS1
- PS
Saturation dissolved oxygen partial pressure
- Rc
dnB/dt coalescence rate
- S
Substrate concentration
- tF
Time since the beginning of the cultivation
- X
Biomass concentration
- V1
Liquid volume in BS1
- wSG
Superficial gas velocity in BS1
-
G
Gas holdup in BS1
- 1
V1/Fv mean liquid residence time in BS1
- BS1
O2 absorber column
- BS2
O2 desorber column
- D
Desmophen (antifoam agent)
- NS
Nutrient salt solution (Table 1) 相似文献