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21.
Hatchery-reared mature male Atlantic salmon parr were shorter than immature parr of the same age through the winter period and this difference increased prior to smolting in spring. Stripping had no effect on growth. In autumn mature male parr had a higher condition factor (CF) than immature parr, but from early January no difference was observed between unstripped mature males and immature parr. Stripping reduced the CF of male parr but the difference had disappeared by the time of smolting when the CFs of both mature groups were lower than that of immature fish. The quantity of expressible milt in stripped males decreased from c . 3% body weight in November and December to <0.05% by 2 March, after which no further milt expression was recorded. Milt expression in previously unstripped males was about 1% of body weight on 2 March, similar to that of stripped males 1 month earlier. 相似文献
22.
Corey M. Helchowski 《Biochemical and biophysical research communications》2009,388(2):240-246
For internalization experiments that use fluorescent antibody (Ab) staining to distinguish between inside versus outside cellular localization of various receptor targeting ligands, it is critical that there be efficient removal of all residual surface-bound fluorescent Ab. To achieve this, a fluorescent Ab removal technique is commonly employed in receptor internalization assays that utilizes low pH glycine-based buffers to wash off the residual non-internalized fluorescent Ab retained on cell surfaces. In this study, we highlight the shortcomings of this technique and propose an alternative in situ proteolytic approach that we found to be non-deleterious to the cells and significantly more effective in removing the residual fluorescence resulting from non-internalized surface-bound Ab. 相似文献
23.
Meruva NK Penn JM Farthing DE 《Journal of industrial microbiology & biotechnology》2004,31(10):482-488
Several microbial volatile organic compounds (MVOCs) that can serve as potential chemical markers for microbial contamination in tobacco have been identified. Four different fungal species, Aspergillus niger (AN), A. ornatus (AO), Pencillium chrysogenum (PC) and Rhizopus stolonifer (RS), commonly reported in moldy tobacco were cultured and screened for MVOCs. Because the MVOCs emitted by a microbial species are substrate specific, the fungal strains were separately grown on potato dextrose agar (PDA) and tobacco products. MVOCs from the mold cultures grown on PDA and tobacco products were extracted using closed-loop stripping analysis (CLSA) and identified by gas chromatography/time-of-flight mass spectrometry (GC/TOF-MS). Some of the prominent tobacco mold markers identified by this method include: 1-octen-3-ol; 2-octen-1-ol; 2-methyl-1-butanol; 3-methyl-1-butanol; 1-octene and 2-pentanone. In particular, 1-octen-3-ol was detected in all the mold cultures and moldy tobacco samples analyzed. Olfactory evaluation of 1-octen-3-ol indicated a characteristic musty odor and the odor threshold was determined to be approximately 200 ng/ml. The limits of detection for 1-octen-3-ol using GC/TOF-MS and GC/mass selective detector (MSD) in the full-scan mode and selected ion monitoring (SIM) mode were investigated. The CLSA-GC/TOF-MS demonstrates a fast, sensitive and semi-quantitative analytical technique for screening tobacco materials for the presence of mold via chemical markers of microbial contamination. 相似文献
24.
Separation and preconcentration of copper and cadmium ions from multielemental solutions using Nostoc muscorum-based biosorbents 总被引:2,自引:0,他引:2
Nostoc-based biosorbents (AlgaSORBs) useful as chromatographic column-packing materials were prepared by immobilizing cyanobacteria
onto solid support in three different fashions: (i) cyanobacterial biofilm (Nostoc-dimethylformamide slurry) over polymer-modified silica gel, (ii) cyanobacterial biofilm over bare silica gel, and (iii) cyanobacteria
as such onto polymer-modified silica gel. The materials were characterized for their stabilities and metal sorption/elution
conditions under static and dynamic equilibrations. Preconcentrated metals from a test sample were detected following `standard
addition' method using a differential pulse anodic stripping voltammetric technique. All sorbents showed 100% affinity for
Cd2+ ion in a multielemental sample at pH 6.9 and a flow rate of 0.5 ml/min with a preconcentration factor varying between 28-
and 75-fold. The first type of AlgaSORB was also found to be selective for Cu2+ ion in multielemental analysis at pH 5.2 and a flow rate of 1.0 ml/min with a preconcentration factor of 75. The low capacity
and favourable kinetics of these sorbents for Cu2+, Cd2+, Zn2+ and Pb2+ ions reflect the suitability of AlgaSORB columns for satisfactory performance in single column ion-chromatography. The polymer
spacer between cyanobacterial biofilm and silica gel plays a vital role in holding the immobilized biofilm resulting in better
endurance and recyclability for the first type of biosorbent.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
25.
DNA immobilized on a nylon membrane can be re-probed multiple times with different probes. Protocols typically recommend that
DNA blots be stored either dry at room temperature or wet at 4 or −20°C after a probe is removed. This study shows substantial
differences in the effect of these storage options on the performance of uncharged nylon membranes in subsequent hybridizations.
Uncharged membranes, air-dried and stored at room temperature after probe removal, could not be successfully re-probed. However,
excellent rehybridization results were obtained following probe removal when wet membranes were wrapped in plastic and stored
at −20°C. 相似文献
26.
27.
Xuefang Li Wanzhi Wei Xiandong Zeng Jinxiang Zeng Jian Yin Ling Wu 《World journal of microbiology & biotechnology》2007,23(10):1465-1471
This paper provided information on the use of linear sweep anodic stripping voltammetry for evaluating the process of copper
biosorption onto Pseudomonas aeruginosa. This technique was suited to determine the concentration of free copper ion on site on the mercaptoethane sulfonate modified
gold electrode surface without any pretreatment. It was in favor of the study of kinetic process as the fast changing kinetic
data characteristic just after the beginning of biosorption could be accurately depicted. Based on the electrochemical results,
the kinetics and equilibrium of biosorption were systematically examined. The pseudo-second-order kinetic model was used to
correlate the kinetic experimental data and the kinetic parameters were evaluated. The Langmuir and Freundlich models were
applied to describe the biosorption equilibrium. It was found that the Langmuir isotherm fitted the experimental data better
than the Freundlich isotherm. Maximum adsorption capacity of copper ion onto Pseudomonas aeruginosa was 0.9355 μmol mg−1 (about 59.4417 mg g−1). 相似文献
28.
29.
Richter H Qureshi N Heger S Dien B Cotta MA Angenent LT 《Biotechnology and bioengineering》2012,109(4):913-921
n‐Butanol was produced continuously in a two‐stage fermentor system with integrated product removal from a co‐feed of n‐butyric acid and glucose. Glucose was always required as a source of ATP and electrons for the conversion of n‐butyrate to n‐butanol and for biomass growth; for the latter it also served as a carbon source. The first stage generated metabolically active planktonic cells of Clostridium saccharoperbutylacetonicum strain N1‐4 that were continuously fed into the second (production) stage; the volumetric ratio of the two fermentors was 1:10. n‐Butanol was removed continuously from the second stage via gas stripping. Implementing a two‐stage process was observed to dramatically dampen metabolic oscillations (i.e., periodical changes of solventogenic activity). Culture degeneration (i.e., an irreversible loss of solventogenic activity) was avoided by periodical heat shocking and re‐inoculating stage 1 and by maintaining the concentration of undissociated n‐butyric acid in stage 2 at 3.4 mM with a pH‐auxostat. The system was successfully operated for 42 days during which 93% of the fed n‐butyrate was converted to n‐butanol at a production rate of 0.39 g/(L × h). The molar yields Yn‐butanol/n‐butyrate and Yn‐butanol/glucose were 2.0, and 0.718, respectively. For the same run, the molar ratio of n‐butyrate to glucose consumed was 0.358. The molar yield of carbon in n‐butanol produced from carbon in n‐butyrate and glucose consumed (Yn‐butanol/carbon) was 0.386. These data illustrate that conversion of n‐butyrate into n‐butanol by solventogenic Clostridium species is feasible and that this can be performed in a continuous system operating for longer than a month. However, our data also demonstrate that a relatively large amount of glucose is required to supply electrons and ATP for this conversion and for cell growth in a continuous culture. Biotechnol. Bioeng. 2012; 109:913–921. © 2011 Wiley Periodicals, Inc. 相似文献
30.