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1.
The mechanism responsible for the initial steps in the anaerobic degradation of trans-cinnamate and -phenylalkane carboxylates by the purple non-sulphur photosynthetic bacterium Rhodopseudomonas palustris was investigated. Phenylacetate did not support growth and there was a marked CO2 dependence for growth on acids with greater side-chain lengths. Here, CO2 was presumably acting as a redox sink for the disposal of excess reducing equivalents. Growth on benzoate did not require the addition of exogenous CO2. Aromatic acids with an odd number of side-chain carbon atoms (3-phenylpropionate, 5-phenylvalerate, 7-phenylheptanoate) gave greater apparent molar growth yields than those with an even number of side-chain carbon atoms (4-phenylbutyrate, 6-phenylhexanoate, 8-phenyloctanoate). HPLC analysis revealed that phenylacetate accumulated and persisted in the culture medium during growth on these latter compounds. Cinnamate and benzoate transiently accumulated in the culture medium during growth on 3-phenylpropionate, and benzoate alone accumulated transiently during the course of trans-cinnamate degradation. The transient accumulation of 4-phenyl-2-butenoic acid occurred during growth on 4-phenylbutyrate, and phenylacetate accumulated to a 1:1 molar stoichiometry with the initial 4-phenylbutyrate concentration. It is proposed that the initial steps in the anaerobic degradation of trans-cinnamate and the group of acids from 3-phenylpropionate to 8-phenyloctanoate involves -oxidation of the side-chain.Abbreviation 3-PP
3-phenylpropionic acid
- 4-PB
4-phenylbutyric acid
- 5-PV
5-phenylvaleric acid
- 6-PH
6-phenylhexanoic acid
- 7-PH
7-phenylheptanoic acid
- 8-PO
8-phenyloctanoic acid
- 4-P2B
4-phenyl-2-butenoic acid
- GC/MS
Gas chromatography/Mass spectrometry
- HPLC
High-pressure liquid chromatography 相似文献
2.
Tjakko Abee Jan Knol Klaas J. Hellingwerf Evert P. Bakker Annette Siebers Wil N. Konings 《Archives of microbiology》1992,158(5):374-380
Cells of the purple non-sulphur bacterium Rhodobacter sphaeroides express a high-affinity K+ uptake system when grown in media with low K+ concentrations. Antibodies againts the catalytic KdpB protein or the whole KdpABC complex of Escherichia coli crossreact with a 70.0 kDa R. sphaeroides protein that was expressed only in cells grown in media with low K+ concentrations. In membranes derived from R. sphaeroides cells grown with low K+ concentrations (induced cells), a high ATPase activity could be detected when assayed in Tris-HCl pH 8.0 containing 1 mM MgSO4. This ATPase activity increased upon addition of 1 mM KCl from 166 to 289 mol ATP hydrolysed x min-1 x g protein-1 (1.7-fold stimulation). The K+-stimulated ATPase activity was inhibited approximately 93% by 0.5 mM vanadate but hardly by N,N-dicyclohexylcarbo-diimide (DCCD). These results indicate that the inducible K+-ATPase in R. sphaeroides resembles the Kdp K+-translocating ATPase of Escherichia coli. This Kdp-like transport system is also expressed in R. capsulatus and Rhodospirillum rubrum during growth in media with low K+ concentrations suggesting a wide distribution of this transport system among phototrophic bacteria.Abbreviations
electrical potential difference across the cytoplasmic membrane
- pH
pH difference across the cytoplasmic membrane
- BSA
bovine serum albumine
- PAGE
polyacrylamide gel electrophoresis
- HEPES
4-(2-hydroxyethyl)-1-piperazine-ethanesulfonic acid
- PMSF
phenyl-methyl-sulfonyl fluoride
- DCCD
N,N-dicyclohexylcarbodiimide
- AIB
2--aminoisobutyric acid
- TMG
methyl--d-thiogalactopyranoside 相似文献
3.
From genomic libraries of the purple non-sulfur bacteria Rhodospirillum rubrum Ha and Rhodobacter sphaeroides ATCC 17023 in the broad-host range cosmid pVK100, we cloned a 15- and a 14-kbp HindIII restriction fragment, respectively. Each of these fragments restored the ability to accumulate poly(3-hydroxybutyrate) (PHB), in the PHB-negative mutant Alcaligenes eutrophus PHB-4. These hybrid cosmids also complemented PHB-negative mutants derived from wild-type R. rubrum or R. sphaeroides. Both fragments hybridized with the PHB synthase structural gene of A. eutrophus H16 and conferred the ability to express PHB synthase activity. Only the 15-kbp HindIII fragment from R. rubrum conferred on the mutant PHB-4 the ability to form large PHB granules (length up to 3.5 microns). 相似文献
4.
Investigations of the uptake of ammonium (NH
4
+
) by Rhodopseudomonas capsulata B100 supported the presence of an NH
4
+
transport system. Experimentally NH
4
+
was determined by electrode or indophenol assay and saturation kinetics were observed with two apparent K
m's of 1.7 M and 11.1 M (pH 6.8, 30°) and a V
max at saturation of 50–60 nmol/min·mg protein. The optimum pH and temperature were 7.0 and 33° C, respectively. The Q10 quotient was calculated to be 1.9 at 100 M NH
4
+
, indicating enzymatic involvement. In contrast to the wild type, B100, excretion of NH
4
+
, not uptake, was observed in a glutamine auxotroph, R. capsulata G29, which is derepressed for nitrogenase and lacks glutamine synthetase activity. G29R1, a revertant of G29, also took up NH
4
+
at the same rate as wild type and had fully restored glutamine synthetase activity. Partially restored derivatives, G29R5 and G29R6, grew more slowly than wild type on NH
4
+
as the nitrogen source, remained derepressed for nitrogenase in the presence of NH
4
+
, and displayed rates of NH
4
+
uptake in proportion to their glutamine synthetase activity. Ammonium uptake and glutamine synthetase activity were also restored in R. capsulata G29 exconjugants which had received the plasmid pPS25, containing the R. capsulata glutamine synthetase structural gene. These data suggest that NH
4
+
transport is tightly coupled to assimilation.Abbreviations used CHES
cyclohexylaminoethanesulfonic acid
- GS
glutamine synthetase
- SDS
sodium dodecylsulfate 相似文献
5.
We have reconstituted pigment-protein complexes isolated from Rhodopseudomonas palustris photosynthetic membranes into phospholipid liposomes. The various complexes were tested for their ability to promote adhesion of the liposome membrane in the presence and absence of Mg2+ ions. Samples containing a reaction center (RC)/light-harvesting I (LHI) complex appeared to stack in a manner resembling control thylakoids in 2 and 5 mM Mg2+. We also tested for the effects of Mg2+ on detergent extractablity of pigment-protein complexes from intact membranes. Mg2+ sharply reduced the amount of LHI solubilized from membranes, while having little effect on the extractability of the light harvesting II complex (LHII) and the RC. Based on these results we suggest that LHI is the principal adhesion factor of R. palustris thylakoids.Abbreviations LHC
light harvesting complex
- OG
octyl glucoside
- RC
reaction center
This paper is dedicated to Professor G. Drews on the occasion of his 60th birthday 相似文献
6.
Francisco Romero Francisco Javier Caballero Francisco Castillo José Manuel Roldán 《Archives of microbiology》1985,143(2):111-116
Anti-glutamine synthetase serum was raised in rabbits by injecting purified glutamine synthetase (GS) of the phototrophic bacterium Rhodopseudomonas capsulata E1F1. The antibodies were purified to monospecificity by immunoaffinity chromatography in GS-sepharose gel. These anti-GS antibodies were used to measure the antigen levels in crude extracts from bacteria, grown phototrophically with dinitrogen, nitrate, nitrite, ammonia, glutamate, glutamine or alanine as nitrogen sources. The amount of GS detected by rocket immunoelectrophoresis was proportional to Mn2+-dependent transferase activity measured in the crude extracts. Addition of GS inhibitor l-methionine-d,l-sulfoximine (MSX) to the actively growing cells promoted increased antigen levels, that were not found in the presence of glutamine or chloramphenicol. The ammonia-induced decrease in GS relative levels was reverted by MSX. GS levels remained constant when phototrophically growing cells were kept in the dark.Abbreviations GS
glutamine synthetase
- MOPS
2-(N-morpholine) propane sulfonate
- MSX
l-methionine-d,l-sulfoximine 相似文献
7.
Proton translocation during the reduction of NO
3
-
, NO
2
-
, N2O and O2, with endogenous substrates, in washed cells of Rhodopseudomonas sphaeroides f. denitrificans was investigated by an oxidant pulse method. On adding NO
2
-
to washed cells, anaerobically in the dark, an alkalinization occurred in the reaction mixture followed by acidification. When NO
3
-
, N2O or O2 was added to cells in the dark or with these compounds and NO
2
-
in light an acidification only was observed. Proton translocation was inhibited by carbonyl cyanide-m-chlorophenyl hydrazone.Valinomycin treated cells produced acid in response to the addition of either NO
3
-
, NO
2
-
, N2O or O2. The proton extrusion stoichiometry (
ratios) in illuminated cells were as follows: NO
3
-
0.5N2, 4.82; NO
2
-
0.5N2, 5.43; N2ON2, 6.20; and O2H2O, 6.43. In the dark the comparable values were 3.99, 4.10, 4.17 and 3.95. Thus, illuminated cells produced higher
values than those in the dark, indicating a close link between photosynthesis and denitrification in the generation of proton gradients across the bacterial cell membranes.When reduced benzyl viologen was the electron donor in the presence of 1 mM N-ethylmaleimide and 0.5 mM 2-n-heptyl-4-hydroxyquinoline-N-oxide in the dark, the addition of either NO
3
-
, NO
2
-
or N2O to washed cells resulted in a rapid alkalinization of the reaction mixture. The stoichiometries for proton consumption,
ratios without a permeant ion were NO
3
-
NO
2
-
,-1.95; NO
2
-
0.5 N2O,-3.03 and N2ON2,-2.02. The data indicate that these reductions occur on the periplasmic side of the cytoplasmic membrane.Abbreviations BVH
reduced benzyl viologen
- CCCP
carbonyl cyanide m-chlorophenyl hydrazone
- DIECA
N, N-diethyl-dithiocarbamate
- HOQNO
2-n-heptyl-4-hydroxyquinoline-N-oxide
- NEM
N-ethylmaleimide 相似文献
8.
The four amino acids of the aspartate family (l-lysine, l-methionine, l-threonine, and l-isoleucine) are produced in bacteria by a branched biosynthetic pathway. Regulation of synthesis of early common intermediates and of carbon flow through distal branches of the pathway requires operation of a number of subtle feedback controls, which are integrated so as to ensure balanced synthesis of the several end products. Earlier studies with nonsulfur purple photosynthetic bacteria were instrumental in revealing the existence of alternative regulatory schemes, and in this communication we report on the control pattern of a representative of this physiological group not previously investigated, Rhodopseudomonas palustris. The results obtained from study of the properties of four key regulatory enzymes of the aspartate family pathway (-aspartokinase, homoserine dehydrogenase, homoserine kinase, and threonine deaminase) and of the effects of exogenous amino acids (i. e., the end products) on growth of the bacterium indicate that the control schema in Rps. palustris differs substantially from the schemes described for other Rhodopseudomonas species, but resembles the regulatory pattern observed in Rhodospirillum rubrum.Abbreviations A
absorbancy
- AK
-aspartokinase
- ASA
aspartate -semialdehyde
- DTT
dithiothreitol
- HS
l-homoserine
- HSDH
homoserine dehydrogenase
- HSK
homoserine kinase
- I
l-isoleucine
- KU
Klett-Summerson photometer units
- L
l-lysine
- M
l-isoleucine
- KU
Klett-Summerson photometer units
- L
l-lysine
- M
l-methionine
- ME
-mercaptoethanol
- PABA
p-aminobenzoic acid
- T
l-threonine
- TD
threonine deaminase
- RCV
synthetic growth medium (see text)
- YP agar
medium containing 0.3% yeast extract, 0.3% peptone, and 1.5% agar
- Y2T
synthetic growth medium (see text) 相似文献
9.
S. Butz R. Benz T. Wacker W. Welte A. Lustig R. Plapp J. Weckesser 《Archives of microbiology》1993,159(4):301-307
Oligomeric porin of the phototrophic bacterium Rhodopseudomonas blastica DSM 2131 was obtained from cell envelopes by differential temperature extraction in the presence of detergent and salt. The isolated porin exhibited strong porin activity after reconstitution into lipid bilayer membranes. The effective channel diameter for the trimer was estimated as 1.5 nm from single channel conductance measurements in the presence of 1 M KCl. Moderate cation-selectivity was observed. Oligomeric porin migrated as a single band (apparent molecular weight 81 kDa) on sodium dodecyl sulfate polyacrylamide gelelectrophoresis when solubilized below 70 °C. The oligomers were converted into monomers on heating to 70 °C or above forming two bands with apparent molecular weight of 36 kDa and 35 kDa. The oligomer was not sensitive to EDTA. Its molecular weight was determined to be 119.3 kDa by analytical ultracentrifugation. The isoelectric point was 5.7. Circular dichroism data indicated a high content of -sheet structure. Gasphase sequencing of the N-terminal residues revealed the sequence: NH2-Glu-Ile-Ser-Leu-Asn-Gly-Tyr-Gly-Arg-Phe. Crystals with a maximal side length of 300 m and diffracting to 0.32 nm resolution were obtained with the porin oligomer in the presence of C8E4 and 1,2,3-heptanetriol by using the vapor phase equilibration technique.Abbreviations C8E4
n-octyl tetraoxyethylene
- Mr
apparent molecular weight
- Octyl-POE
n-octyl polyoxyethylene
- LDAO
N,N-dimethyl dodecyl aminoxide
- LPS
lipopolysaccharide
- PAGE
polyacrylamide gel-electrophoresis
- PEG
polyethylene glycol 相似文献
10.