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991.
Tatiana L. Rose Alexandre da Silva Conceição Jose Xavier-Filho Lev A. Okorokov Kátia V. S. Fernandes Francis Marty Danièle Marty-Mazars André O. Carvalho Valdirene M. Gomes 《Plant and Soil》2006,286(1-2):181-191
Plants exude a variety of substances through their roots, germinating seeds and aerial parts. Some of these released compounds seem to have an inhibitory effect against pathogens. The aim of this work was to investigate and identify antifungal proteins present in exudates from imbibed cowpea seeds (Vigna unguiculata (L.) Walp). The obtained exudation was analyzed in regard to specific protein activities by enzymatic or immunological assays for plant defense proteins, from 4 h to 48 h of seed imbibition. Our results show that cowpea seeds exudates present several defense related proteins characterized as β-1,3-glucanases, cystatins, vicilins and lipid transfer proteins (LTPs), as well as a storage vacuole membrane α-TIP protein, since the very first hours of imbibition. These exudates also have an “in vitro” inhibitory effect on the growth of the fungus Fusarium oxysporum f. sp. phaseoli. Our results suggest that seed exudates should promote seed protection from soil pathogens. 相似文献
992.
Betoni JE Mantovani RP Barbosa LN Di Stasi LC Fernandes Junior A 《Memórias do Instituto Oswaldo Cruz》2006,101(4):387-390
Searches for substances with antimicrobial activity are frequent, and medicinal plants have been considered interesting by some researchers since they are frequently used in popular medicine as remedies for many infectious diseases. The aim of this study was to verify the synergism between 13 antimicrobial drugs and 8 plant extracts--"guaco" (Mikania glomerata), guava (Psidium guajava), clove (Syzygium aromaticum), garlic (Allium sativum), lemongrass (Cymbopogon citratus), ginger (Zingiber officinale), "carqueja" (Baccharis trimera), and mint (Mentha piperita)--against Staphylococcus aureus strains, and for this purpose, the disk method was the antimicrobial susceptibility test performed. Petri dishes were prepared with or without dilution of plant extracts at sub-inhibitory concentrations in Mueller-Hinton Agar (MHA), and the inhibitory zones were recorded in millimeters. In vitro anti-Staphylococcus aureus activities of the extracts were confirmed, and synergism was verified for all the extracts; clove, guava, and lemongrass presented the highest synergism rate with antimicrobial drugs, while ginger and garlic showed limited synergistic capacity. 相似文献
993.
Fernandes L Ceravolo GS Fortes ZB Tostes R Santos RA Santos JA Mori MA Pesquero JB de Carvalho MH 《Regulatory peptides》2006,136(1-3):92-97
We investigated the expression and localization of B1 receptor in tissues of rats submitted to a renin-dependent model of hypertension (2K-1C), and analyzed the influence of endogenous Ang II in modulating the in vivo expression of these receptors. B1 mRNA levels in the heart, kidney and thoracic aorta were quantified by real time PCR, B1 receptor protein expression was assessed by immunohistochemistry, plasma Ang II levels were analyzed by radioimmunoassay and the effects of AT1 receptor blockade were determined after losartan treatment. 2K-1C rats presented a marked increase in Ang II levels when compared to sham-operated rats. In parallel, cardiac- (but not renal and aortic) B1 mRNA levels were 15-fold higher in 2K-1C than in sham rats. In 2K-1C, B1 expression was detected in the endothelium of small cardiac arteries and in cardiomyocytes. Losartan completely reverted the increased B1 mRNA levels and significantly decreased the protein expression observed in 2K-1C rats, despite reducing, but not normalizing blood pressure. We conclude that in the 2K-1C rat, induction of cardiac B1 receptor might be tightly linked to AT1 receptor activation. These data suggest the existence of a new site of interaction between kinins and angiotensins, and might provide important contributions for a better understanding of the pathophysiology of hypertension. 相似文献
994.
Cells in living organisms are regulated by chemical and physical stimuli from their environment. Often, ligands interact with
membrane receptors to trigger responses and Sargent and Schwyzer conceived a model to describe this process, “membrane catalysis”.
There is a notion that the physical organization of membranes can control the response of cells by speeding up reactions.
We revisit the “membrane catalysis” model in the light of recent technical, methodological and theoretical advances and how
they can be exploited to highlight the details of membrane mediated ligand–receptor interactions. We examine the possible
effects that ligand concentration causes in the membrane catalysis and focus our attention in techniques used to determine
the partition constant. The hypothetical diffusional advantage associated with membrane catalysis is discussed and the applicability
of existing models is assessed. The role of in-depth location and orientation of ligands is explored emphasizing the contribution
of new analysis methods and spectroscopic techniques. Results suggest that membranes can optimize the interaction between
ligands and receptors through several different effects but the relative contribution of each must be carefully investigated.
We certainly hope that the conjugation of the methodological and technical advances here reported will revive the interest
in the membrane catalysis model. 相似文献
995.
B. Angelova P. Fernandes A. Cruz H.M. Pinheiro S. Mutafov J.M.S. Cabral 《Enzyme and microbial technology》2005,37(7):718-722
The use of organic solvent-based media for microbial 9-hydroxylation of androstenedione (AD) by resting Rhodococcus sp. cells was evaluated. Product yields higher than 90% were observed in a two-phase phthalate-buffer transformation medium (3:1, v/v) containing 1.0 g L−1 AD. The results suggest that in these conditions the reaction of Δ1-dehydrogenation is considerably inhibited. The successful hydroxylation reaction with a product yield exceeding 60% was found to take place also in a phthalate medium under simultaneous forced aeration and maintenance of a minimum water content of about 3% (v/v). 相似文献
996.
Pereira JM Severino RP Vieira PC Fernandes JB da Silva MF Zottis A Andricopulo AD Oliva G Corrêa AG 《Bioorganic & medicinal chemistry》2008,16(19):8889-8895
Chagas' disease, a parasitic infection caused by the flagellate protozoan Trypanosoma cruzi, is a major public health problem affecting millions of individuals in Latin America. On the basis of the essential role in the life cycle of T. cruzi, the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) has been considered an attractive target for the development of novel antitrypanosomatid agents. In the present work, we describe the inhibitory effects of a small library of natural and synthetic anacardic acid derivatives against the target enzyme. The most potent inhibitors, 6-n-pentadecyl- and 6-n-dodecylsalicilic acids, have IC(50) values of 28 and 55 microM, respectively. The inhibition was not reversed or prevented by the addition of Triton X-100, indicating that aggregate-based inhibition did not occur. In addition, detailed mechanistic characterization of the effects of these compounds on the T. cruzi GAPDH-catalyzed reaction showed clear noncompetitive inhibition with respect to both substrate and cofactor. 相似文献
997.
A. Cruz B. Angelova P. Fernandes J. M. S. Cabral H. M. Pinheiro 《Biocatalysis and Biotransformation》2004,22(3):189-194
The selective side-chain cleavage of β-sitosterol by free cells of Mycobacterium sp. NRRL B-3805 is a well-established multi-enzymatic process for the production of the pharmaceutical steroid precursors androstenedione (AD) and androstadienedione (ADD). In this study, bis(2-ethylhexyl) phthalate (BEHP) was used as a reaction medium for carrying out the process with freely suspended cells. The work aimed to show that microbial sitosterol side-chain cleavage is possible in this essentially mono-phasic organic medium, provided that some important parameters are adequately controlled. The effects of the biocatalyst/substrate mass ratio, system aeration rate and minimum buffer addition to the organic medium on the product yield and the reaction rate were thus evaluated. 相似文献
998.
Sucrose Metabolism in Lupinus albus L. Under Salt Stress 总被引:3,自引:0,他引:3
Salt stress (50 and 150 mM NaCl) effects on sucrose metabolism was determined in Lupinus albus L. Sucrose synthase (SS) activity increased under salt stress and sucrose phosphate synthase activity decreased. Acid invertase
activity was higher at 50 mM NaCl and decreased to control levels at 150 mM NaCl. Alkaline invertase activity increased with
the salt stress. Glucose content decreased with salt stress, sucrose content was almost three times higher in plants treated
with 150 mM NaCl and fructose content did not change significantly. The most significant response of lupin plants to NaCl
excess is the increase of sucrose content in leaves, which is partially due to SS activity increase under salinity.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
999.
Claudino MJ Soares D Van Keulen F Marques MP Cabral JM Fernandes P 《Bioresource technology》2008,99(7):2304-2311
Silicone rubbers are hydrophobic, a feature that may prove advantageous if this material is to be used as immobilization matrix in bioconversion systems where hydrophobic species are present, such as sterols and mycobacterial cells. Mycobacterium sp. cells with sitosterol side chain cleavage activity were accordingly effectively adsorbed onto silicone and the potential application of the concept was assessed by matching the behavior of the resulting immobilized biocatalyst with free cells and Celite immobilized cells. Mass transfer, kinetics, thermal and storage stability characterization of a biotransformation system based in the use of the silicone immobilized biocatalyst was performed. The feasibility of biocatalyst reutilization was tentatively explored. 相似文献
1000.
Fernandes L Fischer FL Ribeiro CW Silveira GP Sá MM Nome F Terenzi H 《Bioorganic & medicinal chemistry letters》2008,18(16):4499-4502
Hydrolysis of DNA is of increasing importance in biotechnology and medicine. In this Letter, we present the DNA-cleavage potential of metal-free hydroxylamines and oximes as new members of nucleic acid cleavage agents. 相似文献