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91.
Characterization of proteoglycans synthesized by rabbit articular chondrocytes in response to transforming growth factor-beta (TGF-beta) 总被引:2,自引:0,他引:2
F Redini M Daireaux A Mauviel P Galera G Loyau J P Pujol 《Biochimica et biophysica acta》1991,1093(2-3):196-206
The effect of transforming growth factor-beta (TGF-beta, 1 ng/ml) on proteoglycan synthesis by rabbit articular chondrocytes in culture was studied in the presence of fetal bovine serum. Exposure of confluent cells for 24 h to the factor resulted in a marked increase of 35S-labeled sulfate incorporation in the newly synthesized proteoglycans (PG), as estimated by glycosaminoglycan (GAG) radioactivity (+58%). The onset was observed 6 h after addition of the factor but was significant after 12 h. TGF-beta also enhanced the uptake of [35S]sulfate by chondrocytes, but had no effect on the release of PG by these cells. The effect of TGF-beta on the distribution of PG between the medium and the cell layer was shown to be dependent on the serum concentration in the medium: the relative proportion of cell-layer associated GAG of TGF-beta-treated cells decreased with increasing concentration of fetal bovine serum. The proportion of aggregated PG, the hydrodynamic size of PG monomers and GAG chains were not modified by TGF-beta, but the relative distribution of disaccharides 6- and 4-sulfate in GAG chains was altered by the factor: the proportion of chondroitin 6-sulfate (C6S) was decreased while that of chondroitin 4-sulfate (C4S) was augmented in presence of TGF-beta, leading to a decrease of the ratio C6S/C4S (-11 to -22%, P less than 0.01). The present study indicates that TGF-beta promotes the synthesis of a modified extracellular matrix in cultured articular chondrocytes. This mechanism could be relevant to some aspects of cartilage repair in osteoarticular diseases. 相似文献
92.
Sharma DK Maldonado JE Jhala YV Fleischer RC 《Proceedings. Biological sciences / The Royal Society》2004,271(Z3):S1-S4
All previously obtained wolf (Canis lupus) and dog (Canis familiaris) mitochondrial (mt) DNA sequences fall within an intertwined and shallow clade (the 'wolf-dog' clade). We sequenced mtDNA of recent and historical samples from 45 wolves from throughout lowland peninsular India and 23 wolves from the Himalayas and Tibetan Plateau and compared these sequences with all available wolf and dog sequences. All 45 lowland Indian wolves have one of four closely related haplotypes that form a well-supported, divergent sister lineage to the wolf-dog clade. This unique lineage may have been independent for more than 400,000 years. Although seven Himalayan wolves from western and central Kashmir fall within the widespread wolf-dog clade, one from Ladakh in eastern Kashmir, nine from Himachal Pradesh, four from Nepal and two from Tibet form a very different basal clade. This lineage contains five related haplotypes that probably diverged from other canids more than 800,000 years ago, but we find no evidence of current barriers to admixture. Thus, the Indian subcontinent has three divergent, ancient and apparently parapatric mtDNA lineages within the morphologically delineated wolf. No haplotypes of either novel lineage are found within a sample of 37 Indian (or other) dogs. Thus, we find no evidence that these two taxa played a part in the domestication of canids. 相似文献
93.
Carlos Roberto Maximiano da Silva Leandro Bento da Silva Célia Guadalupe Tardelli de Jesus Andrade Rafael Trevisan María Socorro González-Elizondo André Luís Laforga Vanzela 《Plant Systematics and Evolution》2012,298(2):391-398
Micromorphology of the achene surface of 26 Brazilian species of Eleocharis was studied by scanning electron microscopy in order to evaluate its usefulness in the taxonomy of the genus. The results
point out two patterns of cell organization according to silica structures of achenes. The first corresponds to a group of
species (group A) that have small to medium cells arranged vertically. The second is found in those species (group B) with
medium to large cells arranged horizontally. These data were useful in separating species of Eleocharis subgenus Scirpidium and E. subgenus Limnochloa (group B) from E. subgenus Eleocharis (group A). However, group A shows considerable variation in silica wall arrangement. Eleocharis
squamigera, previously considered as part of E. subgenus Eleocharis, shows features rather similar to those of Scirpidium, confirming recent phylogenies. The subgenus Limnochloa was clearly distinguished from others by achenes with large cells (over 55 μm width), presence of crenate or repand anticlinal
walls, and some orifices near the wall in some species. The silica wall ornamentation seems to be a useful morphological tool
for studying relationships between subgenera and distinguishes Limnochloa from the other subgenera. 相似文献
94.
95.
Molecular characterization of a fourth isoform of the catalytic subunit of protein phosphatase 2A from Arabidopsis thaliana 总被引:1,自引:0,他引:1
Antonio Casamayor Encarna Pérez-Callejón Gemma Pujol Joaquín Ariño Albert Ferrer 《Plant molecular biology》1994,26(1):523-528
We have recently reported the existence of multiple isoforms of the catalytic subunit of protein phosphatase 2A (PP2A) in Arabidopsis thaliana and the molecular cloning of cDNAs encoding three of these proteins (PP2A-1, PP2A-2, PP2A-3). The reported cDNA encoding PP2A-3 was truncated at the 5 terminus, lacking a short fragment of the N-terminal coding sequence. We have now isolated a near full-length cDNA encoding the entire PP2A-3 protein (313 residues). The clone includes 188 nucleotides of 5-untranslated region, where a 44 bp long poly(GA) track is found. We also describe the cloning of a cDNA encoding a fourth isoform of PP2A (PP2A-4). The polypeptide contains 313 residues being 98% identical to PP2A-3 and only 80% identical to both PP2A-1 and PP2A-2. The mRNA for PP2A-4 is 1.4 kb in length and, although predominantly expressed in roots, it is also found in other organs. It is concluded that in A. thaliana the isoforms of PP2A can be grouped in two extremely conserved subfamilies. 相似文献
96.
Two polyphenol oxidases (enzymes A and B) from Bartlett pear (Pyrus communis) peelings were purified to electrophoretic homogeneity according to polyacrylamide gel by a combination of Sephadex gel filtration, diethylaminoethyl cellulose chromatography and hydroxyl apatite chromatography. While the two enzymes differ electrophoretically at pH 9.3, chromatographically on hydroxyl apatite, and in the effect of ionic strength on activity, they are similar with respect to chromatography on diethylaminoethyl cellulose, substrate specificity, pH activity relations, inhibition by p-coumaric and benzoic acids, and heat stability. The two enzymes are o-diphenol oxidases with no detectable monophenolase or laccase activities. Pyrocatechol, 4-methyl catechol, chlorogenic acid, and d-catechin are good substrates of the enzymes with Km values in the range of 2 to 20 mm. Dependences of activity on oxygen and chlorogenic acid concentrations indicate a sequential mechanism for binding of these substrates to enzyme B. Vmax and Km values for oxygen and chlorogenic acid were 103 μmoles O2 uptake per minute per milligram of enzyme, 0.11 mm and 7.2 mm, respectively, for enzyme B at pH 4.0. Both enzymes had maximum activity at pH 4.0 on chlorogenic acid. Km values for chlorogenic acid were independent of pH from 3 to 7; the Vmax values for both enzymes gave bell-shaped curves as a function of pH. p-Coumaric acid is a simple, linear noncompetitive inhibitor with respect to chlorogenic acid at pH 6.2 with Ki values of 0.38 and 0.50 mm for enzymes A and B, respectively. Benzoic acid is a linear competitive inhibitor with respect to chlorogenic acid at pH 4.0 with Ki values of 0.04 and 0.11 mm for enzymes A and B, respectively. 相似文献
97.
Casagrande F Ratera M Schenk AD Chami M Valencia E Lopez JM Torrents D Engel A Palacin M Fotiadis D 《The Journal of biological chemistry》2008,283(48):33240-33248
The L-arginine/agmatine antiporter AdiC is a key component of the arginine-dependent extreme acid resistance system of Escherichia coli. Phylogenetic analysis indicated that AdiC belongs to the amino acid/polyamine/organocation (APC) transporter superfamily having sequence identities of 15-17% to eukaryotic and human APC transporters. For functional and structural characterization, we cloned, overexpressed, and purified wild-type AdiC and the point mutant AdiC-W293L, which is unable to bind and consequently transport L-arginine. Purified detergent-solubilized AdiC particles were dimeric. Reconstitution experiments yielded two-dimensional crystals of AdiC-W293L diffracting beyond 6 angstroms resolution from which we determined the projection structure at 6.5 angstroms resolution. The projection map showed 10-12 density peaks per monomer and suggested mainly tilted helices with the exception of one distinct perpendicular membrane spanning alpha-helix. Comparison of AdiC-W293L with the projection map of the oxalate/formate antiporter from Oxalobacter formigenes, a member from the major facilitator superfamily, indicated different structures. Thus, two-dimensional crystals of AdiC-W293L yielded the first detailed view of a transport protein from the APC superfamily at sub-nanometer resolution. 相似文献
98.
99.
Vanessa Carregaro José M. Ribeiro Jesus G. Valenzuela Djalma L. Souza-Júnior Diego L. Costa Carlo J. F. Oliveira Laís A. Sacramento Manuela S. L. Nascimento Cristiane M. Milanezi Fernando Q. Cunha Jo?o S. Silva 《PLoS neglected tropical diseases》2015,9(4)
Background
Sand fly saliva plays a crucial role in establishing Leishmania infection. We identified adenosine (ADO) and adenosine monophosphate (AMP) as active pharmacologic compounds present in Phlebotomus papatasi saliva that inhibit dendritic cell (DC) functions through a PGE2/IL 10-dependent mechanism.Methodology/Principal Findings
Herein, we prepared a mixture of ADO and AMP in equimolar amounts similar to those present in the salivary-gland extract (SGE) form one pair of salivary glands of P. papatasi and co-injected it with Leishmania amazonensis or L. major into mouse ears. ADO+AMP mimicked exacerbative effects of P. papatasi saliva in leishmaniasis, increasing parasite burden and cutaneous lesions. Enzymatic catabolism of salivary nucleosides reversed the SGE-induced immunosuppressive effect associated with IL-10 enhancement. Immunosuppressive factors COX2 and IL-10 were upregulated and failed to enhance ear lesion and parasite burden in IL 10-/- infected mice. Furthermore, nucleosides increased regulatory T cell (Treg) marker expression on CD4+CD25- cells, suggesting induction of Tregs on effector T cells (T eff). Treg induction (iTreg) was associated with nucleoside-induced tolerogenic dendritic cells (tDCs) expressing higher levels of COX2 and IL-10. In vitro generation of Tregs was more efficient in DCs treated with nucleosides. Suppressive effects of nucleosides during cutaneous leishmaniasis were mediated through an A2AR-dependent mechanism. Using BALB/c mice deficient in A2A ADO receptor (A2AR–/–), we showed that co-inoculated mice controlled infection, displaying lower parasite numbers at infection sites and reduced iTreg generation.Conclusion/Significance
We have demonstrated that ADO and AMP in P. papatasi saliva mediate exacerbative effects of Leishmania infection by acting preferentially on DCs promoting a tolerogenic profile in DCs and by generating iTregs in inflammatory foci through an A2AR mechanism. 相似文献100.
Anna Santoro Javier Conde Morena Scotece Vanessa Abella Ana Lois Veronica Lopez Jesus Pino Rodolfo Gomez Juan J. Gomez-Reino Oreste Gualillo 《PloS one》2015,10(8)