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981.
982.
Cunha Ade C Chierrito TP Machado GM Leon LL da Silva CC Tanaka JC de Souza LM Gon?alves RA de Oliveira AJ 《Phytomedicine》2012,19(5):413-417
The present study was designated to evaluate semi-quantitative antileishmanial activity of alkaloidal extracts that were obtained from 1g of different parts of Aspidosperma ramiflorum (leaves, roots, seeds, and stem barks). Alkaloidal extracts of barks and leaves presented a good activity against the extracellular form (promastigotes) of Leishmania (L.) amazonensis. It is known that compounds responsible for the antileishmanial activity in the alkaloidal extracts from A. ramiflorum are the monoterpenoid indole alkaloids ramiflorine A and ramiflorine B, therefore extracts obtained from different plant parts were analyzed by electrospray ionization mass spectrometry (ESI-MS) in order to evidence the presence of these bioactive alkaloids. Based on these findings, alkaloidal extract from leaves was fractionated on preparative thin-layer chromatography in a bioassay-guided fractionation affording individual purified ramiflorines A and B. Both ramiflorines A and B showed significant activity against Leishmania (L.) amazonensis (LD(50) values of 18.5±6.5μg/ml and 12.63±5.52μg/ml, respectively). Our results are showing that alkaloidal extract from leaves is a promising alternative to the use of stem barks from A. ramiflorum. 相似文献
983.
The yeast bud site selection system represents a paradigm for understanding how fungal cells regulate the formation of a polarity axis. In Saccharomyces cerevisiae, Bud4 and Axl2 are components of the axial bud site marker. To address the possibility that these proteins regulate cellular morphogenesis in filamentous fungi, we have characterized homologues of Bud4 and Axl2 in Aspergillus nidulans. Our results show that Bud4 is involved in septum formation in both hyphae and developing conidiophores. Whereas Axl2 appears to have no obvious role in hyphal growth, it is required for the regulation of phialide morphogenesis during conidiation. In particular, Axl2 localizes to the phialide-spore junction, where it appears to promote the recruitment of septins. Furthermore, the developmental regulators BrlA and AbaA control the expression of Axl2. Additional studies indicate that Axl2 is also involved in the regulation of sexual development, not only in A. nidulans, but also in the phylogenetically unrelated fungus Fusarium graminearum. Our results suggest that Axl2 plays a key role in phialide morphogenesis and/or function during conidiation in the aspergilli. 相似文献
984.
Danielle Karla Alves da Silva Camilla Maciel Rabelo Pereira Renata Gomes de Souza Gladstone Alves da Silva Fritz Oehl Leonor Costa Maia 《Biodiversity and Conservation》2012,21(9):2361-2373
Strong anthropogenic pressure, mainly mineral extraction, is one of the main factors leading to degradation of the Brazilian coastal environment. Strategies to recover these areas include replanting native plant species, and symbiotic fungi from the neighboring area might be important for the establishment of the new vegetation. Species richness, diversity and community composition of arbuscular mycorrhizal fungi (AMF) were investigated in NE Brazil in two natural areas, ‘restinga’ forest and seaside ‘restinga’, and in two areas of revegetated dunes after mining activity 20 and 8?years ago. Soil samples were collected during the dry (March) and wet (September) seasons of 2009 in Mataraca, Paraíba State, Brazil. Based on glomerospore morphology, 34 species of AMF were recorded, of which 29 were identified in field samples and five after trap culturing, with the greatest diversity and richness found in the dune revegetated 8?years ago. The sampling effort allowed an assessment of between 70 and 80?% of the species estimated for the areas by the first-order Jackknife index. Among the generalist species Gigaspora margarita was the only one found in all areas and during both collection periods. The similarity of AMF species between the revegetated areas and the seaside ‘restinga’ was >60?%, supporting the hypothesis that this area represents a source of propagules, but the substrate used for seedling production may also bring other species, enabling the recovery of the AMF community in the mined and revegetated dunes. 相似文献
985.
Lacerda DI Cysne-Finkelstein L Nunes MP De-Luca PM Genestra Mda S Leon LL Berrêdo-Pinho M Mendonça-Lima L Matos DC Medeiros MA de Mendonça SC 《Memórias do Instituto Oswaldo Cruz》2012,107(2):238-245
In Leishmania amazonensis, kinetoplastid membrane protein-11 (KMP-11) expression increases during meta-cyclogenesis and is higher in amastigotes than in promastigotes, suggesting a role for this protein in the infection of the mammalian host. We show that the addition of KMP-11 exacerbates L. amazonensis infection in peritoneal macrophages from BALB/c mice by increasing interleukin (IL)-10 secretion and arginase activity while reducing nitric oxide (NO) production. The doses of KMP-11, the IL-10 levels and the intracellular amastigote loads were strongly, positively and significantly correlated. The increase in parasite load induced by KMP-11 was inhibited by anti-KMP-11 or anti-IL-10 neutralising antibodies, but not by isotype controls. The neutralising antibodies, but not the isotype controls, were also able to significantly decrease the parasite load in macrophages cultured without the addition of KMP-11, demonstrating that KMP-11-induced exacerbation of the infection is not dependent on the addition of exogenous KMP-11 and that the protein naturally expressed by the parasite is able to promote it. In this study, the exacerbating effect of KMP-11 on macrophage infection with Leishmania is for the first time demonstrated, implicating it as a virulence factor in L. amazonensis. The stimulation of IL-10 production and arginase activity and the inhibition of NO synthesis are likely involved in this effect. 相似文献
986.
Mendoza-Juez B Martínez-González A Calvo GF Pérez-García VM 《Bulletin of mathematical biology》2012,74(5):1125-1142
We propose a mathematical model of tumor cell nutrient uptake governed by the presence of two key biomolecular fuels: glucose
and lactate. The model allows us to describe, in a remarkably simple way, different in vitro scenarios previously reported
in experiments of tumor cell metabolism using distinct energy sources. The predictions of our model show good agreement with
all the examined tumor cell lines (cervix, colon, and glioma) and provide a first step toward the development of more comprehensive
frameworks accounting for in vivo cancer dynamics under complex spatial heterogeneities. 相似文献
987.
988.
989.
Calvo E Barasoain I Matesanz R Pera B Camafeita E Pineda O Hamel E Vanderwal CD Andreu JM López JA Díaz JF 《Biochemistry》2012,51(1):329-341
Cyclostreptin is the first microtubule-stabilizing agent whose mechanism of action was discovered to involve formation of a covalent bond with tubulin. Treatment of cells with cyclostreptin irreversibly stabilizes their microtubules because cyclostreptin forms a covalent bond to β-tubulin at either the T220 or the N228 residue, located at the microtubule pore or luminal taxoid binding site, respectively. Because of its unique mechanism of action, cyclostreptin overcomes P-glycoprotein-mediated multidrug resistance in tumor cells. We used a series of reactive cyclostreptin analogues, 6-chloroacetyl-cyclostreptin, 8-chloroacetyl-cyclostreptin, and [(14)C-acetyl]-8-acetyl-cyclostreptin, to characterize the cellular target of the compound and to map the binding site. The three analogues were cytotoxic and stabilized microtubules in both sensitive and multidrug resistant tumor cells. In both types of cells, we identified β-tubulin as the only or the predominantly labeled cellular protein, indicating that covalent binding to microtubules is sufficient to prevent drug efflux mediated by P-glycoprotein. 6-Chloroacetyl-cyclostreptin, 8-chloroacetyl-cyclostreptin, and 8-acetyl-cyclostreptin labeled both microtubules and unassembled tubulin at a single residue of the same tryptic peptide of β-tubulin as was labeled by cyclostreptin (219-LTTPTYGDLNHLVSATMSGVTTCLR-243), but labeling with the analogues occurred at different positions of the peptide. 8-Acetyl-cyclostreptin reacted with either T220 or N228, as did the natural product, while 8-chloroacetyl-cyclostreptin formed a cross-link to C241. Finally, 6-chloroacetyl-cyclostreptin reacted with any of the three residues, thus labeling the pathway for cyclostreptin-like compounds, leading from the pore where these compounds enter the microtubule to the luminal binding pocket. 相似文献
990.
Moreira CK Capurro Mde L Calvo E Silva PI James AA deBianchi AG Marinotti O 《Insect biochemistry and molecular biology》2003,33(4):389-395
The Musca domestica larval hexamerin (MdHex-L) is a hexameric glycoprotein with an apparent native molecular weight of 500 kDa. Seven different cDNAs that encode MdHex-L subunits were cloned and sequenced. Furthermore, amino acid sequences of isolated subunits were determined by the Edman degradation method and compared to the conceptual translation products derived from the cloned cDNAs. The obtained data indicate the existence of multiple forms of MdHex-L subunits and that these multiple forms may be grouped into three categories according to their percentages of nucleotide sequence identity. 相似文献