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191.
Wuhrer M Grimm C Zahringer U Dennis RD Berkefeld CM Idris MA Geyer R 《Glycobiology》2003,13(2):129-137
The acidic (glyco)lipids of the parasitic liver fluke Fasciola hepatica exhibited two different phosphate-containing species, designated AL-I and AL-II, which were analyzed by MALDI-TOF MS, ESI MS, NMR, methylation analysis, and combined GC-MS in conjunction with HF treatment. AL-I was structurally determined as 1-O-hexadecyl-sn-glycerol-3-phosphoinositol, an ether bond variant of lysophosphatidylinositol. The structure of AL-II was shown to be GlcNAcalpha1-HPO3-6Gal(1-1)ceramide. Ceramide analysis revealed as major components 2-hydroxyoctadecanoic acid [18:0(2-OH)] together with C18- and C20-phytosphingosines. AL-II was apparently highly antigenic and strongly recognized by both animal- and human-F. hepatica infection sera. Furthermore, inhibition ELISAs revealed that the unusual antigenic determinant GlcNAcalpha1-HPO3- phosphate might have a potential in the serodiagnosis of F. hepatica infections. 相似文献
192.
Coulet M Eeckhoutte C Larrieu G Sutra JF Alvinerie M Macé K Pfeifer A Zucco F Stammati AL De Angelis I Vignoli AL Galtier P 《Chemico-biological interactions》2000,127(2):109-124
Thiabendazole (TBZ), an anthelmintic and fungicide benzimidazole, was recently demonstrated to be extensively metabolized by cytochrome P450 (CYP) 1A2 in man and rabbit, yielding 5-hydroxythiabendazole (5OH-TBZ), the major metabolite furtherly conjugated, and two minor unidentified metabolites (M1 and M2). In this study, exposure of rabbit and human cells to 14C-TBZ was also shown to be associated with the appearance of radioactivity irreversibly bound to proteins. The nature of CYP isoforms involved in this covalent binding was investigated by using cultured rabbit hepatocytes treated or not with various CYP inducers (CYP1A1/2 by beta-naphthoflavone, CYP2B4 by phenobarbital, CYP3A6 by rifampicine, CYP4A by clofibrate) and human liver and bronchial CYP-expressing cells. The covalent binding to proteins was particularly increased in beta-naphthoflavone-treated rabbit cells (2- to 4-fold over control) and human cells expressing CYP1A2 (22- to 42-fold over control). Thus, CYP1A2 is a major isoenzyme involved in the formation of TBZ-derived residues bound to protein. Furthermore, according to the good correlation between covalent binding and M1 or 5OH-TBZ production, TBZ would be firstly metabolized to 5OH-TBZ and subsequently converted to a chemically reactive metabolic intermediate binding to proteins. This metabolic activation could take place preferentially in liver and lung, the main biotransformation organs, rather than in intestines where TBZ was shown to be not metabolized. Moreover, TBZ was rapidly transported by passive diffusion through the human intestinal cells by comparison with the protein-bound residues which were not able to cross the intestinal barrier. Consequently, the absence of toxicity measured in intestines could be related to the low degree of TBZ metabolism and the lack of absorption of protein adducts. Nevertheless, caution is necessary in the use of TBZ concurrently with other drugs able to regulate CYP1A2, particularly in respect to liver and lung tissues, recognised as sites of covalent-binding. 相似文献
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Transgenic Arabidopsis plants can accumulate polyhydroxybutyrate to up to 4% of their fresh weight 总被引:7,自引:0,他引:7
Bohmert K Balbo I Kopka J Mittendorf V Nawrath C Poirier Y Tischendorf G Trethewey RN Willmitzer L 《Planta》2000,211(6):841-845
Transgenic Arabidopsis thaliana (L.) Heynh. plants expressing the three enzymes encoding the biosynthetic route to polyhydroxybutyrate (PHB) are described.
These plants accumulated more than 4% of their fresh weight (≈40% of their dry weight) in the form of PHB in leaf chloroplasts.
These very high producers were obtained and identified following a novel strategy consisting of a rapid GC-MS analysis of
a large number of transgenic Arabidopsis plants generated using a triple construct, thus allowing the parallel transfer of all three genes necessary for PHB synthesis
in a single transformation event. The level of PHB produced was 4-fold greater than previously published values, thus demonstrating
the large potential of plants to produce this renewable resource. However, the high levels of the polymer produced had severe
effects on both plant development and metabolism. Stunted growth and a loss of fertility were observed in the high-producing
lines. Analysis of the metabolite composition of these lines using a GC-MS method that we have newly developed showed that
the accumulation of high levels of PHB was not accompanied by an appreciable change in either the composition or the amount
of fatty acids. Substantial changes were, however, observed in the levels of various organic acids, amino acids, sugars and
sugar alcohols.
Received: 2 February 2000 / Accepted: 31 March 2000 相似文献
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196.
Utility of Green Fluorescent Nucleic Acid Dyes and Aluminum Oxide Membrane Filters for Rapid Epifluorescence Enumeration of Soil and Sediment Bacteria 总被引:14,自引:7,他引:7
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High background fluorescence and unspecific staining hampered the epifluorescence enumeration of bacteria in 45% of the tested soil and sediment samples with 4′,6-diamidino-2-phenylindole (DAPI) and polycarbonate membrane filters. These problems of the determination of total cell counts can be circumvented by using green fluorescent high-affinity nucleic acid dyes and aluminum oxide membrane filters. Due to the bright staining of cells, we recommend SYBR Green II as dye. 相似文献
197.
Delphine S. Dupuis Christiane Palmier Francis C. Colpaert Petrus J. Pauwels 《Journal of neurochemistry》1998,70(3):1258-1268
Abstract: G protein activation mediated by serotonin 5-HT1A and 5-HT1B/D receptors in guinea pig brain was investigated by using quantitative autoradiography of agonist-stimulated [35S]GTPγS binding to brain sections. [35S]GTPγS binding was stimulated by the mixed 5-HT1A/5-HT1B/D agonist L694247 in brain structures enriched in 5-HT1A binding sites, i.e., hippocampus (+140 ± 14%), dorsal raphe (+70 ± 8%), lateral septum (+52 ± 12%), cingulate (+36 ± 8%), and entorhinal cortex (+34 ± 5%). L694247 caused little or no stimulation of [35S]GTPγS binding in brain regions with high densities of 5-HT1B/D binding sites (e.g., substantia nigra, striatum, central gray, and dorsal subiculum). The [35S]GTPγS binding response was antagonized by WAY100635 (10 µM) and methiothepin (10 µM). In contrast, the 5-HT1B inverse agonist SB224289 (10 µM) did not affect the L694247-mediated [35S]GTPγS binding response, and the mixed 5-HT1B/D antagonist GR127935 (10 µM) yielded a partial blockade. The distribution pattern of the [35S]GTPγS binding response and the antagonist profile suggest the L694247-mediated response in guinea pig brain to be mediated by 5-HT1A receptors. In addition to L694247, 8-hydroxy-2-(di-n-propylamino)tetralin, and flesinoxan also stimulated [35S]GTPγS binding; their maximal responses varied between 46 and 52% compared with L694247, irrespective of the brain structure being considered. Sumatriptan, rizatriptan, and zolmitriptan (10 µM) stimulated [35S]GTPγS binding in the hippocampus by 20–50%. Naratriptan, CP122638, and dihydroergotamine stimulated [35S]GTPγS binding to a similar level as L694247 in hippocampus, lateral septum, and dorsal raphe. It appears that under the present experimental conditions, G protein activation through 5-HT1A but not 5-HT1B/D receptors can be measured in guinea pig brain sections. 相似文献
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