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81.
82.
83.
K Hochstrasser P Reisinger G J Albrecht E Wachter O L Sch?nberger 《Hoppe-Seyler's Zeitschrift für physiologische Chemie》1984,365(9):1123-1130
Two crude fractions of acid-resistant trypsin inhibitors (apparent molecular masses 44 and 20 kDa, respectively) were prepared from human urine by gel permeation chromatography. From both preparations the pure inhibitors were isolated by high performance liquid chromatography (HPLC). Their N-terminal amino-acid sequences were determined and compared with those of HI-30 and HI-14 as isolated by reversible binding to either immobilized trypsin or immobilized chymotrypsin. The N-terminal amino-acid sequence of the high-molecular mass inhibitor UI-I isolated by HPLC was identical with those of HI-30 and UI-C-I isolated via immobilized trypsin or chymotrypsin, respectively. The low-molecular mass inhibitors UI-II and UI-C-II differ from HI-14 by the N-terminal extension Glu-Val-Thr-Lys-when obtained by HPLC or by the extension Thr-Lys-when obtained via immobilized chymotrypsin, respectively. The comparison of these N-termini with the amino-acid sequence of HI-30 (Ala1-...-Val16-Thr-Glu-Val-Thr-Lys-HI-14) defines the low molecular urinary trypsin inhibitors as proteolytic degradation products of the high-molecular urinary inhibitor. Proteolysis may occur at different bonds. The existing discrepancies in molecular architecture and in molecular masses of the urinary trypsin inhibitors are discussed. 相似文献
84.
Purification and properties of a stilbene synthase from induced cell suspension cultures of peanut 总被引:16,自引:0,他引:16
Stilbene synthase ( resveratrol -forming) converts one molecule of rho- coumaroyl -CoA and three molecules of malonyl-CoA into 3,4',5- trihydroxystilbene . Following selective induction of stilbene synthesis in cell suspension cultures of peanut (Arachis hypogaea), the enzyme was extracted and purified to apparent homogeneity by chromatography on DEAE-cellulose and hydroxylapatite. The enzyme was found to be a dimer of estimated Mr = 90,000 exhibiting under denaturing conditions a subunit Mr of approximately 45,000. The isoelectric point was determined with pI = 4.8. The enzyme's high selectivity towards rho- coumaroyl -CoA (Km = 2 microM) as substrate qualified it as resveratrol -forming stilbene synthase. Structurally related CoA esters, e.g. dihydro-rho- coumaroyl -CoA and cinnamoyl-CoA, were converted less than 1/10 as efficiently as rho- coumaroyl -CoA. Malonyl-CoA (Km = 10 microM) could not be substituted by acetyl-CoA. The purified enzyme was free of chalcone synthase activity. Antibodies raised against stilbene synthase were shown to be monospecific and not to cross-react with chalcone synthase. 相似文献
85.
Dr. A. Gebauer Dr. T. Scheper Prof. Dr. K. Schügerl 《Bioprocess and biosystems engineering》1987,2(2):55-58
Enzyme production with E. coli ATCC 11105, in a complex medium using phenylacetic acid as inducer is carried out in a stirred-tank reactor of 10 dm3 and an airlift tower-loop reactor of 60 dm3 with outer loop at a temperature of 27 °C. The optimum inducer concentration was 0.8 kg/m3, which was kept constant by fed-batch operation. The optimum of the relative dissolved O2-concentration with regard to saturation is below 10% in a stirred-tank reactor and at 35% in a tower-loop reactor. It was kept constant by parameter-adaptive control of the aeration rate. In a stirred-tank enzyme productivity is slightly higher than in a tower-loop reactor, and much higher than in a bubble column reactor.List of Symbols CPR kg/(m3 h)
CO2-production rate
- OTR kg/(m3 h)
O2-transfer rate
- OUR kg/(m3 h)
O2-utilization rate
- PAA
phenylacetic acid (inducer)
- RQ = CPR/OUR
respiratory quotient
-
X kg/m3
cell mass concentration
-
m h–1
maximum specific growth rate 相似文献
86.
Dr. A. Gebauer Dr. T. Scheper Prof. Dr. K. Schügerl 《Bioprocess and biosystems engineering》1987,2(1):13-23
E. coli ATCC 11105 was cultivated in a 10-1 stirred tank reactor and in a 60-1 tower loop reactor in batch and continuous operation. By on-line measurements of O2 and CO2 concentrations in the outlet gas, pH, temperature, cell mass concentration X as well as dissolved O2 concentration along the tower in the broth, gas holdup, broth recirculation rate through the loop and by offline measurements of substrate concentration DOC and cell mass concentration along the tower, the maximum specific growth rate
m
, yield coefficients Y
X/S. Y
X/DOC and
were evaluated in stirred tank and tower loop in batch and continuous cultures with and without motionless mixers in the tower and at different broth circulation rates through the loop. To control the accuracy of the measurements the C balance was calculated and 95% of the C content was covered.The biological parameters determined depend on the mode of operation as well as on the reactor used. Furthermore, they depend on the recirculation rate of the broth and built-ins in the tower. The unstructured cell and reactor models are unable to explain these differences. Obviously, structured cell and reactor models are needed. The cell mass concentration can be determined on line by NADH fluorescence in balanced growth, if the model parameters are determined under the same operational conditions in the same reactor.List of Symbols
a, b
empirical parameters in Eq. (1)
- CPR kg/(m3 h)
CO2 production rate
-
C kg/m3
concentration
-
D l/h
dilution rate
- DOC kg/m3
dissolved organic carbon
-
I
net. fluorescence intensity
-
K
S
kg/m3
Monod constant
-
k
L
a l/h
volumetric mass transfer coefficient
- OTR kg/(m3 h)
oxygen transfer rate
- OUR kg/(m3 h)
oxygen utilization rate
- RQ = CPR/OUR
respiratory quotient
-
S kg/m3
substrate concentration
-
t h,min, s
time
-
t
u
min
recirculation time
-
t
M
min
mixing time
-
v m3/h
volumetric flow rate through the loop
-
X kg/m3
(dry) cell mass concentration
-
Y
X/S
yield coefficient of cell mass with regard to the consumed substrate
-
Y
X/DOC
yield coefficient of the cell mass with regard to the consumed DOC
-
Y
X/O
yield coefficient of the cell mass with regard to the consumed oxygen
-
Z
relative distance in the tower from the aerator with regard to the height of the aerated broth
-
l/h
specific growth rate
-
m
l/h
maximum specific growth rate
Indices
f
feed
-
e
outlet 相似文献
87.
Spatiotemporal receptive fields: a dynamical model derived from cortical architectonics 总被引:1,自引:0,他引:1
G Krone H Mallot G Palm A Schüz 《Proceedings of the Royal Society of London. Series B, Containing papers of a Biological character. Royal Society (Great Britain)》1986,226(1245):421-444
We assume that the mammalian neocortex is built up out of some six layers which differ in their morphology and their external connections. Intrinsic connectivity is largely excitatory, leading to a considerable amount of positive feedback. The majority of cortical neurons can be divided into two main classes: the pyramidal cells, which are said to be excitatory, and local cells (most notably the non-spiny stellate cells), which are said to be inhibitory. The form of the dendritic and axonal arborizations of both groups is discussed in detail. This results in a simplified model of the cortex as a stack of six layers with mutual connections determined by the principles of fibre anatomy. This stack can be treated as a multi-input-multi-output system by means of the linear systems theory of homogeneous layers. The detailed equations for the simulation are derived in the Appendix. The results of the simulations show that the temporal and spatial behaviour of an excitation distribution cannot be treated separately. Further, they indicate specific processing in the different layers and some independence from details of wiring. Finally, the simulation results are applied to the theory of visual receptive fields. This yields some insight into the mechanisms possibly underlying hypercomplexity, putative nonlinearities, lateral inhibition, oscillating cell responses, and velocity-dependent tuning curves. 相似文献
88.
Chris L. Schürmann Jan A. R. A. M. van Hooff 《International journal of primatology》1986,7(3):265-287
Recent field data indicate that MacKinnon’s model of the orang-utan’s sexual and agonistic activity needs to be revised. In
this model, male reproductive activity is concentrated in an extended phase of subadulthood and in early adulthood. According
to this model, the role of older adult males is primarily that of range guardian, and in that role they would ensure that
the offspring they had generated earlier would have safe access to food resources. This study presents cases suggesting that
subadult males, even though sexually active, may have low reproductive success. In previous studies adult males were shown
to display less sexual initiative than subadult males. In this study an adult male was at times involved infrequent mating
activity in response to proceptive activity of females in the course of consortship. This adult male proved to be a successful
breeder, thus refuting the hypothesis of adult male sterility. The female is most likely to conceive through cooperative mating
in lengthy consortships with the dominant resident adult male. We hypothesize that the extended subadult phase represents
a submissive strategy, allowing subadult males to remain in the home range of adult males but with minimal reproductive success. 相似文献
89.
Günther Schünzel Gerald Wolf Fritz Rothe Eberhard Seidler 《Cellular and molecular neurobiology》1986,6(1):31-42
Transmitter glutamate/aspartate synthesis is known to proceed along different metabolic pathways. In this light, the functional relevance of glutamate dehydrogenase in postnatally maturing glutamatergic/aspartatergic structures was studied by means of quantitative enzyme histochemistry. The basic requirements concerning the kinetics and calibration of the histochemical glutamate dehydrogenase reaction used were proved to be met in order to obtain valid quantitative data. The histochemically demonstrable activity of glutamate dehydrogenase (EC 1.4.1.3) in the hippocampal formation of the rat increased markedly during postnatal development. On day 30, the distribution pattern observed was similar to that in adult animals. While the enzyme activity rose within cell body layers from day 0 to day 30 by 240-285%, the increase in neuropil layers was found to be up to 830%. Maximum values were seen in the stratum lacunosum-moleculare of CA1 and CA3 and the stratum moleculare of the dentate fascia on day 30. Since the hippocampal neuropil is supposed to be copiously provided with glutamatergic (and aspartatergic?) structures which become functional in rats during the first weeks of postnatal life, the increase in enzyme activity is discussed to be primarily a consequence of maturing synaptic systems using glutamate and/or aspartate as transmitters. 相似文献
90.
Peptide patterns and immunological properties of the cytoplasmic and chloroplastic -1,4-glucan phosphorylase (EC 2.4.1.1) from spinach leaves have been studied and were compared with those of phosphorylases from other sources. The two spinach leaf phosphorylases were immunologically different; a limited cross-reactivity was observed only at high antigen or antibody concentrations. Peptide mapping of the two enzymes resulted in complex patterns composed of more than 20 fragments; but no peptide was electrophoretically identical in both proteins. Approximately 13 to 15 of the fragments exhibited antigeneity but no cross-reactivity of any peptide was observed. Therefore, the two compartment-specific phosphorylase forms from spinach leaves represent isoenzymes possessing different primary structures. Peptide patterns of potato tuber and rabbit muscle phosphorylase were different from those of the two spinach leaf enzymes. Although the potato tuber phosphorylase resides in the plastidic compartment and is kinetically closely related to the chloroplastic spinach enzyme, it reacted more strongly with the anti-cytoplasmic-phosphorylase immunoglobulin G. Similar results were obtained with rabbit muscle phosphorylase. These observations support the assumption that the chloroplast-specific phosphorylase isoenzyme has a higher structural diversity than does the cytoplasmic counterpart.Abbreviations EDTA
ethylenediaminetetraacetic acid
- Hepes
4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid
- PEG
polyethylene glycol (approx. MW 8000)
I=Schächtele and Steup 1986 相似文献