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661.
Annalisa Tassoni Nello Bagni Maura Ferri Marina Franceschetti Alex Khomutov Maria Paula Marques Sonia M. Fiuza Alina R. Simonian Donatella Serafini-Fracassini 《Plant Physiology and Biochemistry》2010,48(7):496-505
The earliest studies concerning polyamines (PAs) in plants were performed by using in vitro cultured explants of Helianthus tuberosus dormant tuber. This parenchyma tissue was particularly useful due to its susceptibility to several growth substances, including PAs. During tuber dormancy, PA levels are too low to sustain cell division; thus Helianthus represents a natural PA-deficient model. When cultivated in vitro in the presence of auxins, Helianthus tuber dormant parenchyma cells at the G0 stage start to divide synchronously acquiring meristematic characteristics. The requirement for auxins to induce cell division can be substituted by aliphatic PAs such as putrescine, spermidine or spermine. Cylinders or slices of explanted homogeneous tuber parenchyma were cultured in liquid medium for short-term studies on the cell cycle, or on solid agar medium for long-term experiments. Morphological and physiological modifications of synchronously dividing cells were studied during the different phases of the cell cycle in relation to PAs biosynthesis and oxidation. Long-term experiments led to the identification of the PAs as plant growth regulators, as the sole nitrogen source, as tuber storage substances and as essential factors for morphogenetic processes and cell homeostasis. More recently this system was used to study the effects on plant cell proliferation of platinum- or palladium-derived drugs (cisplatin and platinum or palladium bi-substituted spermine) that are used in human cancer cell lines as antiproliferative and cytotoxic agents. Cisplatin was the most active both in cell proliferation inhibition and on PA metabolism. Similar experiments were performed using three agmatine analogous. Different effects of these compounds were observed on cell proliferation, free PA levels and enzyme activities, leading to a hypothesis of a correlation between their chemical structure and the agmatine metabolism in plants. 相似文献
662.
Feniouk BA Rebecchi A Giovannini D Anefors S Mulkidjanian AY Junge W Turina P Melandri BA 《Biochimica et biophysica acta》2007,1767(11):1319-1330
H(+)-F(O)F(1)-ATP synthase couples proton flow through its membrane portion, F(O), to the synthesis of ATP in its headpiece, F(1). Upon reversal of the reaction the enzyme functions as a proton pumping ATPase. Even in the simplest bacterial enzyme the ATPase activity is regulated by several mechanisms, involving inhibition by MgADP, conformational transitions of the epsilon subunit, and activation by protonmotive force. Here we report that the Met23Lys mutation in the gamma subunit of the Rhodobacter capsulatus ATP synthase significantly impaired the activation of ATP hydrolysis by protonmotive force. The impairment in the mutant was due to faster enzyme deactivation that was particularly evident at low ATP/ADP ratio. We suggest that the electrostatic interaction of the introduced gammaLys23 with the DELSEED region of subunit beta stabilized the ADP-inhibited state of the enzyme by hindering the rotation of subunit gamma rotation which is necessary for the activation. 相似文献
663.
Donatella Valdembri Patrick T Caswell Kurt I Anderson Juliane P Schwarz Ireen Knig Elena Astanina Francesca Caccavari Jim C Norman Martin J Humphries Federico Bussolino Guido Serini 《PLoS biology》2009,7(1)
Neuropilin 1 (Nrp1) is a coreceptor for vascular endothelial growth factor A165 (VEGF-A165, VEGF-A164 in mice) and semaphorin 3A (SEMA3A). Nevertheless, Nrp1 null embryos display vascular defects that differ from those of mice lacking either VEGF-A164 or Sema3A proteins. Furthermore, it has been recently reported that Nrp1 is required for endothelial cell (EC) response to both VEGF-A165 and VEGF-A121 isoforms, the latter being incapable of binding Nrp1 on the EC surface. Taken together, these data suggest that the vascular phenotype caused by the loss of Nrp1 could be due to a VEGF-A164/SEMA3A-independent function of Nrp1 in ECs, such as adhesion to the extracellular matrix. By using RNA interference and rescue with wild-type and mutant constructs, we show here that Nrp1 through its cytoplasmic SEA motif and independently of VEGF-A165 and SEMA3A specifically promotes α5β1-integrin-mediated EC adhesion to fibronectin that is crucial for vascular development. We provide evidence that Nrp1, while not directly mediating cell spreading on fibronectin, interacts with α5β1 at adhesion sites. Binding of the homomultimeric endocytic adaptor GAIP interacting protein C terminus, member 1 (GIPC1), to the SEA motif of Nrp1 selectively stimulates the internalization of active α5β1 in Rab5-positive early endosomes. Accordingly, GIPC1, which also interacts with α5β1, and the associated motor myosin VI (Myo6) support active α5β1 endocytosis and EC adhesion to fibronectin. In conclusion, we propose that Nrp1, in addition to and independently of its role as coreceptor for VEGF-A165 and SEMA3A, stimulates through its cytoplasmic domain the spreading of ECs on fibronectin by increasing the Rab5/GIPC1/Myo6-dependent internalization of active α5β1. Nrp1 modulation of α5β1 integrin function can play a causal role in the generation of angiogenesis defects observed in Nrp1 null mice. 相似文献
664.
Silvia Primativo Donatella Spinelli Pierluigi Zoccolotti Maria De Luca Marialuisa Martelli 《PloS one》2016,11(4)
Adults read at high speed, but estimates of their reading rate vary greatly, i.e., from 100 to 1500 words per minute (wpm). This discrepancy is likely due to different recording methods and to the different perceptual and cognitive processes involved in specific test conditions. The present study investigated the origins of these notable differences in RSVP reading rate (RR). In six experiments we investigated the role of many different perceptual and cognitive variables. The presence of a mask caused a steep decline in reading rate, with an estimated masking cost of about 200 wpm. When the decoding process was isolated, RR approached values of 1200 wpm. When the number of stimuli exceeded the short-term memory span, RR decreased to 800 wpm. The semantic context contributed to reading speed only by a factor of 1.4. Finally, eye movements imposed an upper limit on RR (around 300 wpm). Overall, data indicate a speed limit of 300 wpm, which corresponds to the time needed for eye movement execution, i.e., the most time consuming mechanism. Results reconcile differences in reading rates reported by different laboratories and thus provide suggestions for targeting different components of reading rate. 相似文献
665.
Bruno Maras Sofia Valiante Roberta Chiaraluce Valerio Consalvi Laura Politi Mario De Rosa Francesco Bossa Roberto Scandurra Donatella Barra 《The protein journal》1994,13(2):253-259
The complete amino acid sequence of glutamate dehydrogenase from the archaebacteriumPyrococcus furiosus has been determined. The sequence was reconstructed by automated sequence analysis of peptides obtained after cleavage with cyanogen bromide, Asp-N endoproteinase, trypsin, or pepsin. The enzyme subunit is composed of 420 amino acid residues yielding a molecular mass of 47,122 D. In the recently determined primary structure of glutamate dehydrogenase from another thermophilic archaebacterium,Sulfolobus solfataricus, the presence of some methylated lysines was detected and the possible role of this posttranslational modification in enhancing the thermostability of the enzyme was discussed (Maras, B., Consalvi, V., Chiaraluce, R., Politi, L., De Rosa, M., Bossa, F., Scandurra, R., and Barra, D. (1992),Eur. J. Biochem. 203, 81–87). In the primary structure reported here, such posttranslational modification has not been found, indicating that the role of lysine methylation should be revisited. Comparison of the sequence of glutamate dehydrogenase fromPyrococcus furiosus with that ofS. solfataricus shows a 43.7% similarity, thus indicating a common evolutionary pathway. 相似文献
666.
de Pascale D Cusano AM Autore F Parrilli E di Prisco G Marino G Tutino ML 《Extremophiles : life under extreme conditions》2008,12(3):311-323
The genome of the Antarctic bacterium Pseudoalteromonas haloplanktis TAC125 was searched for the presence of genes encoding ester-hydrolysing enzymes. Amongst the others, the gene PSHAa0051
coding for a putative secreted esterase/lipase was selected. The psychrophilic gene was cloned, functionally over-expressed
in P. haloplanktis TAC125, and the recombinant product (after named PhTAC125 Lip1) was purified. PhTAC125 Lip1 was found to be associated to the outer membrane and exhibited higher enzymatic activity towards synthetic substrates
with long acyl chains. A structural model was constructed using the structure of carboxylesterase Est30 from Geobacillus stearothermophilus as template. The model covered the central part of the protein with the exceptions of PhTAC125 Lip1 N- and C-terminal regions, where the psychrophilic protein displays extra-domains. The constructed model showed
a typical α/β-hydrolase fold, and confirmed the presence of a canonical catalytic triad consisting of Ser, Asp and His. The
sequence analysis showed that PhTAC125 Lip1 is distantly related to other lipolytic enzymes, but closely related to other putative psychrophilic esterases/lipases.
The aligned proteins share common features, such as: (1) a conserved new active-site pentapeptide motif (LGG(F/L/Y)STG); (2)
the likely extra-cytoplasmic localization, (3) the absence of a typical calcium-binding pocket, and (4) the absence of a canonical
lid. These observations strongly suggest that aligned proteins constitute a novel lipase family, typical of psychrophilic
marine γ-proteobacteria, and PhTAC125 Lip1 could be considered the first characterised member of this family.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
D. de Pascale and A. M. Cusano equally contributed to the work. 相似文献
667.
Marazziti D Baroni S Fabbrini L Italiani P Catena M Dell'Osso B Betti L Giannaccini G Lucacchini A Cassano GB 《Neurochemical research》2006,31(3):361-365
The dopamine transporter (DAT) is a protein regulating dopamine concentration in the synaptic cleft through the re-uptake mechanism. The DAT is the main target of psychostimulants and seems to play a pivotal role in neuronal degeneration and different neuropsychiatric disorders involving the dopamine system. Exhaustive research, however, regarding the presence of this protein in human platelets is still inconclusive, although it is thought that it might provide a peripheral tool to serve as a mean of exploring the same structure present in the brain. Therefore, we assessed some binding assays in platelets derived from healthy human subjects by means of 3H-WIN 35,428, a compound which is considered a selective ligand for the labelling of this protein, and by means of 125I-RTI-121, another compound with high specificity for DAT. The results showed that the binding of 3H-WIN-35,428 was too low to enable the detection of any structure; the binding of 125I-RTI-121, on the other hand, revealed the presence of two binding sites with pharmacological profiles similar to that of the serotonin transporter (SERT). In conclusions, therefore, platelets would not seem to be a useful model for exploring the DAT, given the prevalence therein of the SERT and the difficulty of labelling the DAT with the currently available ligands. 相似文献
668.
In plants the post-translational modification of proteins by polyamines catalysed by transglutaminases has been studied since
1987; it was identified by the production of glutamyl-polyamine derivatives, biochemical features, recognition by animal antibodies
and modification of typical animal substrates. Transglutaminases are widespread in all plant organs and cell compartments
studied until now, chloroplast being the most studied. Substrates are: photosynthetic complexes and Rubisco in chloroplasts,
cytoskeleton and cell wall proteins. Roles either specific of plants or in common with animals are related to photosynthesis,
fertilisation, stresses, senescence and programmed cell death, showing that the catalytic function is conserved across the
kingdoms. AtPng1p, the first plant transglutaminase sequenced shows undetectable sequence homology to the animal enzymes,
except for the catalytic triad. It is, however, endowed with a calcium-dependent activity that allowed us to build a three-dimensional
model adopting as a template the animal tranglutaminase 2. 相似文献
669.
Clara Iannuzzi Margherita Borriello Antonella D’Agostino Donatella Cimini Chiara Schiraldi Ivana Sirangelo 《Journal of cellular physiology》2019,234(4):3814-3828
Glycosaminoglycans are extracellular matrix components related to several biological functions and diseases. Chondroitin sulfate is a sulphated glycosaminoglycan synthesized as part of proteoglycan molecules. They are frequently associated with amyloid deposits and possess an active role in amyloid fibril formation. Recently, a neuroprotective effect of extracellular matrix components against amyloid toxicity and oxidative stress has been reported. Advanced glycation end products (AGEs), the end products of the glycation reaction, have been linked to amyloid-based neurodegenerative disease as associated with oxidative stress and inflammation. In this study we have analyzed the effect of chondroitin sulfate isolated from different species, in comparison with a new biotechnological unsulfated chondroitin, in the amyloid aggregation process of insulin, as well as the ability to prevent the formation of AGEs and related toxicity. The results have showed a determining role of chondroitin sulfate groups in modulating insulin amyloid aggregation. In addition, both sulfated and unsulfated chondroitins have shown protective properties against amyloid and AGEs-induced toxicity. These data are very relevant as a protective effect of these glycosaminoglycans in the AGE-induced toxicity was never observed before. Moreover, considering the issues related to the purity and safety of chondroitin from natural sources, this study suggests a new potential application for the biotechnological chondroitin. 相似文献
670.
Montesano V Negro D Sarli G De Lisi A Laghetti G Hammer K 《Journal of ethnobiology and ethnomedicine》2012,8(1):15
ABSTRACT: BACKGROUND: The paper refers to the knowledge and uses of plants and to the linked ritual practices as referred by Matteo (It.'Zi Matteo', En. 'Uncle Matthew'), one of the last elder healers in the Basilicata Region (South Italy). Particular attention is also paid to the uses of 'Vruca' (Tamarix gallica L.) as a medicinal and magical plant used to heal common warts on various parts of the body. METHODS: After obtaining prior informed consent, we collected data through an open interview about the uses of the plants and on the associated ritual practices. For each species, data were collected that included the vernacular names, preparation, plant parts utilized and their method of use. RESULTS: The uses of 52 taxa are described. Among these, 43 are or were employed medicinally, eight as culinary foodstuffs, and 4 for domestic, handicraft or ethnoveterinary uses. Among the major findings: the ritual and magical use of Tamarix gallica L. to heal warts is described in detail; so far, no records of similar use were found in any Italian ethnobotanical studies conducted in southern Italy. CONCLUSION: Phytotherapy in the Basilicata region is practiced by elderly people who resort to medicinal plants for mild illnesses; we interviewed one of those traditional healers who is very experienced in the field, and possesses rich ethno-pharmacological knowledge. 相似文献