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21.
Synthesis of reference standards is needed to determine the presence and function of steroid glucuronides in the brain or other tissues, because commercial sources of steroid glucuronide standards are limited or unavailable. In the present study porcine, rat, and bovine liver microsomes were tested to evaluate their ability to glucuronidate eight neurosteroids and neuroactive steroids of various types: dehydroepiandrosterone, pregnenolone, isopregnanolone, 5alpha-tetrahydrodeoxycorticosterone, corticosterone, cortisol, beta-estradiol, and testosterone. In general, the glucuronidation efficiency of rat liver was rather poor compared with that of bovine and porcine liver microsomes. Since porcine liver apparently has a relatively large amount of dehydrogenase, its microsomes also produced dehydrogenated steroids and their glucuronides, as well as various regioisomers in which the site of glucuronidation varied. In contrast, bovine liver microsomes produced mainly a single major glucuronidation product and few dehydrogenation products and gave the best overall yield for two-third of the steroids tested. The enzymatic synthesis of five glucuronides of four steroids was carried out and the conditions, purification, and analytical methods for the glucuronidation products were optimized. The steroid glucuronides synthesized were characterized by nuclear magnetic resonance spectroscopy (NMR) and liquid chromatography-mass spectrometry (LC-MS). The stereochemically pure steroid glucuronide conjugates were recovered in milligram amounts (yield 10-78%) and good purity (>85-90%), which is sufficient for LC-MS/MS method development and analyses of steroid glucuronides in biological matrices such as brain, urine, or plasma. 相似文献
22.
Kim H Blomqvist Jesper Lundbom Nina Lundbom Raimo E Sepponen 《Biomedical engineering online》2011,10(1):1-9
Background
Parkinson's disease (PD) is a neurodegenerative disorder resulting in motor disturbances that can impact normal gait. Although PD initially responds well to pharmacological treatment, as the disease progresses efficacy often fluctuates over the course of the day, and clinical management would benefit from long-term objective measures of gait. We have previously described a small device worn on the shank that uses acceleration and angular velocity sensors to calculate stride length and identify freezing of gait in PD patients. In this study we extend validation of the gait monitor to 24-h using simultaneous video observation of PD patients.Methods
A sleep laboratory was adapted to perform 24-hr video monitoring of patients while wearing the device. Continuous video monitoring of a sleep lab, hallway, kitchen and conference room was performed using a 4-camera security system and recorded to hard disk. Subjects (3) wore the gait monitor on the left shank (just above the ankle) for a 24-h period beginning around 5 pm in the evening. Accuracy of stride length measures were assessed at the beginning and end of the 24-h epoch. Two independent observers rated the video logs to identify when subjects were walking or lying down.Results
The mean error in stride length at the start of recording was 0.05 m (SD 0) and at the conclusion of the 24 h epoch was 0.06 m (SD 0.026). There was full agreement between observer coding of the video logs and the output from the gait monitor software; that is, for every video observation of the subject walking there was a corresponding pulse in the monitor data that indicated gait.Conclusions
The accuracy of ambulatory stride length measurement was maintained over the 24-h period, and there was 100% agreement between the autonomous detection of locomotion by the gait monitor and video observation. 相似文献23.
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Rasimus S Mikkola R Andersson MA Teplova VV Venediktova N Ek-Kommonen C Salkinoja-Salonen M 《Applied and environmental microbiology》2012,78(10):3732-3743
Paenilide is a novel, heat-stable peptide toxin from Paenibacillus tundrae, which colonizes barley. P. tundrae produced 20 to 50 ng of the toxin mg(-1) of cells (wet weight) throughout a range of growth temperatures from +5°C to +28°C. Paenilide consisted of two substances of 1,152 Da and 1,166 Da, with masses and tandem mass spectra identical to those of cereulide and a cereulide homolog, respectively, produced by Bacillus cereus NS-58. The two components of paenilide were separated from those of cereulide by high-performance liquid chromatography (HPLC), showing a structural difference suggesting the replacement of O-Leu (cereulide) by O-Ile (paenilide). The exposure of porcine spermatozoa and kidney tubular epithelial (PK-15) cells to subnanomolar concentrations of paenilide resulted in inhibited motility, the depolarization of mitochondria, excessive glucose consumption, and metabolic acidosis. Paenilide was similar to cereulide in eight different toxicity endpoints with porcine and murine cells. In isolated rat liver mitochondria, nanomolar concentrations of paenilide collapsed respiratory control, zeroed the mitochondrial membrane potential, and induced swelling. The toxic effect of paenilide depended on its high lipophilicity and activity as a high-affinity potassium ion carrier. Similar to cereulide, paenilide formed lipocations, i.e., lipophilic cationic compounds, with K(+) ions already at 4 mM [K(+)], rendering lipid membranes electroconductive. Paenilide-producing P. tundrae was negative in a PCR assay with primers specific for the cesB gene, indicating that paenilide was not a product of plasmid pCER270, encoding the biosynthesis of cereulide in B. cereus. Paenilide represents the first potassium ionophoric compound described for Paenibacillus. The findings in this paper indicate that paenilide from P. tundrae is a potential food-poisoning agent. 相似文献
26.
Falasca P Evangelista G Cotugno R Marco S Masullo M De Vendittis E Raimo G 《Extremophiles : life under extreme conditions》2012,16(3):539-552
The endogenous components of the thioredoxin system in the Antarctic eubacterium Pseudoalteromonas haloplanktis have been purified and characterised. The temperature dependence of the activities sustained by thioredoxin (PhTrx) and thioredoxin reductase (PhTrxR) pointed to their adaptation in the cold growth environment. PhTrxR was purified as a flavoenzyme and its activity was significantly enhanced in the presence of molar concentration of monovalent
cations. The energetics of the partial reactions leading to the whole electron transfer from NADPH to the target protein substrate
in the reconstituted thioredoxin system was also investigated. While the initial electron transfer from NADPH to PhTrxR was energetically favoured, the final passage to the heterologous protein substrate enhanced the energetic barrier of
the whole process. The energy of activation of the heat inactivation process essentially reflected the psychrophilic origin
of PhTrxR. Vice versa, PhTrx possessed an exceptional heat resistance (half-life, 4.4 h at 95 °C), ranking this protein among the most thermostable
enzymes reported so far in psychrophiles. PhTrxR was covalently modified by glutathione, mainly by its oxidised or nitrosylated forms. A mutagenic analysis realised on
three non catalytic cysteines of the flavoenzyme allowed the identification of C303 as the target for the S-glutathionylation reaction. 相似文献
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Paavo N?rhi Maarit Middleton Nils Gustavsson Eija Hyv?nen Marja-Liisa Sutinen Raimo Sutinen 《Biogeochemistry》2011,102(1-3):239-249
To focus conservation efforts into forest areas with high biodiversity, more information is needed about soil-vegetation dependencies in Finnish Lapland. We studied understory vegetation and soil variables along a transect across a felsic?Cmafic lithological sequence in central Finnish Lapland. At 119 northern boreal forest sites, coverages of understory vegetation, several mineral soil chemical elements, soil electrical conductivity, pH, and dielectric permittivity, as a measure of soil volumetric water content, were measured. We found that soil Ca concentration and Ca:Al ratio were the main variables determining vegetation composition and diversity. Ca-rich soils were characterised by high electrical conductivity, pH, and Mg concentration, and by low concentration of Al, S, Zn, and low C:N ratio. Soil Ca concentration is a diagnostic measure of plant diversity as concentration higher than 100 mg kg?1 resulted in a considerable increase in plant diversity. Sites with Ca concentration this high were rare, and probably important in maintaining high biodiversity. The median soil Ca:Al ratio was only 0.02, suggesting, according to general theory, a considerable risk for aluminium stress. We found Geranium sylvaticum and Rubus saxatilis to be good indicators for Ca-rich regimes and high plant diversity. 相似文献