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排序方式: 共有363条查询结果,搜索用时 15 毫秒
91.
Jason Pierson José Jesús Fernández Erik Bos Shoaib Amini Helmut Gnaegi Matthijn Vos Bennie Bel Freek Adolfsen José L. Carrascosa Peter J. Peters 《Journal of structural biology》2010,169(2):219-225
Cryo-electron tomography of vitreous cryo-sections is the most suitable method for exploring the 3D organization of biological samples that are too large to be imaged in an intact state. Producing good quality vitreous cryo-sections, however, is challenging. Here, we focused on the major obstacles to success: contamination in and around the microtome, and attachment of the ribbon of sections to an electron microscopic grid support film. The conventional method for attaching sections to the grid has involved mechanical force generated by a crude stamping or pressing device, but this disrupts the integrity of vitreous cryo-sections. Furthermore, attachment is poor, and parts of the ribbon of sections are often far from the support film. This results in specimen instability during image acquisition and subsequent difficulty with aligning projection images.Here, we have implemented a protective glove box surrounding the cryo-ultramicrotome that reduces the humidity around and within the microtome during sectioning. We also introduce a novel way to attach vitreous cryo-sections to an EM grid support film using electrostatic charging. The ribbon of vitreous cryo-sections remains in place during transfer and storage and is devoid of stamping related artefacts. We illustrate these improvements by exploring the structure of putative cellular 80S ribosomes within 50 nm, vitreous cryo-sections of Saccharomyces cerevisiae. 相似文献
92.
93.
Amini H Javan M Ahmadiani A 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2006,830(2):368-371
Sensitive and selective determination of valproic acid in plasma by high-performance liquid chromatography (HPLC) is usually achieved with pre-column derivatization. In the present work, the derivatization is omitted due to using a simple but highly selective plasma extraction procedure and an optimized chromatographic condition. Valproic acid and the internal standard octanoic acid were extracted from plasma samples with n-hexane under acidic condition followed by back-extraction into diluted triethylamine. Chromatography was performed on a CN column (250 x 4.6 mm, 5 microm) under isocratic elution with acetonitrile-40 mM aqueous sodium dihydrogen phosphate (30:70, v/v), pH 3.5. Detection was made at 210 nm and analyses were run at a flow-rate of 1 ml/min. The method was specific and sensitive with a quantification limit of 1.25 microg/ml and a detection limit of 0.1 microg/ml in plasma. The mean absolute recovery for valproic acid using the present plasma extraction procedure was 75.8%. The intra- and inter-day coefficient of variation and percent error values of the assay method were all in acceptable range. Calibration curves were linear (r>0.999) from 1.25 to 320 microg/ml in plasma. 相似文献
94.
Mohammad Ali Faramarzi Mojtaba Tabatabaei Yazdi Hadi Ghostinroudi Mohsen Amini Younes Ghasemi Hoda Jahandar Homeira Arabi 《Annals of microbiology》2006,56(3):253-256
Nostoc muscorum PTCC 1636 was examined for its ability to convert androst-4-en-3,17-dione (AD) and androst-1,4-dien-3,17-dione (ADD) to their 17-hydroxy related derivatives in BG-11 medium. Bioconversion procedures were carried out at 25 °C without shaking. The metabolites obtained were purified using chromatographic methods and characterized as testosterone and 1-dehydrotestosterone on the basis of their spectroscopic features. In both cases, the bioreaction characteristics observed were 17-carbonyl reduction. 相似文献
95.
Protein pattern changes in tomato under in vitro salt stress 总被引:2,自引:0,他引:2
F. Amini A. A. Ehsanpour Q. T. Hoang J. Sh. Shin 《Russian Journal of Plant Physiology》2007,54(4):464-471
The investigation of salt-induced changes in the proteome would highlight important genes because of a high resolution of
protein separation by two-dimensional gel electrophoresis (2-DE) and protein identification by mass spectrometry and database
search. Tomato (Lycopersicon esculentum Mill.) is a model plant for studying the mechanisms of plant salt tolerance. Seeds of tomato cv. Shirazy were germinated
on water-agar medium. After germination, seedlings were transferred to Murashige and Skoog nutrient medium supplemented with
0, 40, 80, 120, and 160 mM NaCl. After 24 days, leaf and root samples were collected for protein extraction and shoot dry
weight measurement. Alterations induced in leaf and root proteins under salt stress treatments were studied by one-dimensional
SDS-PAGE. Leaf proteins were also analyzed by 2-DE. With increasing salt concentration in the medium, shoot dry weight decreased.
SDS-PAGE showed induction of at least five proteins with mol wts of 30, 62, and 75 kD in roots and 38 and 46 kD in leaves.
On the 2-DE gel, more than 400 protein spots were reproducibly detected. At least 18 spots showed significant changes under
salt stress. Three of them corresponded to new proteins, while six proteins were up-regulated and five proteins were down-regulated
by salt stress. In addition, salinity inhibited the synthesis of four leaf proteins. Ten spots were analyzed by matrix-assistant
laser desorption/ionization-time of flight (MALDI-TOF), which led to the identification of some proteins, which could play
a physiological role under salt stress. The expression of new proteins(enoyl-CoA hydratase, EGF receptor-like protein, salt
tolerance protein, phosphoglycerate mutase-like protein, and M2D3.3 protein) under salt stress indicates that tomato leaf
cells respond to salt stress by changes in different physiological processes. All identified proteins are somehow related
to various salt stress responses, such as cell proliferation.
Published in Russian in Fiziologiya Rastenii, 2007, Vol. 54, No. 4, pp. 526–533.
The text was submitted by the authors in English. 相似文献
96.
97.
Yazdi MT Arabi H Faramarzi MA Ghasemi Y Amini M Shokravi S Mohseni FA 《Phytochemistry》2004,65(15):2205-2209
Hydrocortisone was converted in the culture of an isolated strain of the cyanobacterium Nostoc muscorum PTCC 1636 into some androstane and pregnane derivatives. The microorganism was, isolated during a screening program from soil samples collected from paddy fields of north of Iran. The bioproducts obtained were purified using chromatographic methods and identified as 11beta-hydroxytestosterone, 11beta-hydroxyandrost-4-en-3,17-dione and 11beta,17alpha,20beta,21-tetrahydroxypregn-4-en-3-one on the basis of their spectroscopic features. 相似文献
98.
Nigar Sehrish Nazneen Shahla Khan Sardar Ali Neelum Sarwar Tasneem 《Journal of Plant Growth Regulation》2023,42(1):121-133
Journal of Plant Growth Regulation - The response of Vigna radiata L. (mung bean) to tropospheric ozone (O3) phytotoxicity using Ethylenediurea (EDU) and magnesium nitrate (Mg(NO3)2,... 相似文献
99.
100.
Bahrami G Mirzaeei S Mohammadi B Kiani A 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2005,822(1-2):322-325
Topiramate has no ultraviolet, visible or fluorescence absorption. Analysis of the drug in human serum has been reported by high performance liquid chromatography (HPLC) with either mass detector or fluorescence detection after precolumn derivatization using 9-fluorenylmethyl chloroformate as fluorescent labeling agent. This study was aimed to validate derivatization and analysis of topiramate in human serum with HPLC using UV detection. The drug was extracted from human serum by liquid-liquid extraction and subjected to derivatization with 9-fluorenylmethyl chloroformate. Analysis was performed on a phenyl column using of spectrophotometer detection operated at wavelength of 264 nm. A mixture of phosphate buffer (0.05M) containing triethylamine (1 ml/l, v/v; pH 2.3) and methanol (28:72, v/v) at a flow rate of 2.5 ml/min was used as mobile phase. No interference was found with endogenous substances. Validity of the method was studied and the method was precise and accurate with a linearity range from 40 ng/ml to 40 microg/ml. The limit of quantification was 40 ng/ml of serum. The correlation coefficient between HPLC methods using fluorescence and UV detections was studied and found to be 0.992. 相似文献