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551.
552.
Priscila Fernandes De Souza Cristina M. Ribas Dos Santos Joseph Ree Miguel Pedro Guerra Rosete Pescador 《Grana》2021,60(1):20-34
Abstract Little is known about the reproduction of Dendrocalamus asper because it flowers only every 100 to 120 years. In the present work we describe some reproductive features of this bamboo and characterise flowers and pollen at various developmental stages. Number of pollen grains and ovules per flower, pollen/ovule ratio, in vitro twinning and pollen grain viability in vivo were evaluated and the different stages of floral development identified. Further, we performed a morphological analysis of androecium and pollen development. Seven distinct stages of flower development were identified; four initial stages, a pre-anthetic stage, and two stages of anthetic. Dendrocalamus asper pseudospikelets avoid inbreeding by means of protogyny. The floral and pollen characteristics suggest that the species is anemophilous. The ultrastructural characteristics of free microspores (stage two of floral development), vacuolated microspores (stage five) and mature pollen (anthetic) were analysed. During maturation, pollen grains accumulate larger and more numerous amyloplasts and organelles such as mitochondria. Pollen disperse in the tricellular development stage. Pollen is monoporate with an operculum-like pore, with a rugulate structure and a spinose tectum. 相似文献
553.
Thamires Quadros Froes Bianca Trindade Chaves Marina Sena Mendes Rafael Matos Ximenes Ivanildo Mangueira da Silva Priscila Brando Gomes da Silva Julianna Ferreira Cavalcanti de Albuquerque Marcelo Santos Castilho 《Journal of enzyme inhibition and medicinal chemistry》2021,36(1):1217
The thiazolidinone ring is found in compounds that have widespan biology activity and there is mechanism-based evidence that compounds bearing this moiety inhibit P. aeruginosa PhzS (PaPzhS), a key enzyme in the biosynthesis of the virulence factor named pyocyanin. Ten novel thiazolidinone derivatives were synthesised and screened against PaPhzS, using two orthogonal assays. The biological results provided by these and 28 other compounds, whose synthesis had been described, suggest that the dihydroquinazoline ring, found in the previous hit (A- Kd = 18 µM and LE = 0.20), is not required for PaPzhS inhibition, but unsubstituted nitrogen at the thiazolidinone ring is. The molecular simplification approach, pursued in this work, afforded an optimised lead compound (13- 5-(2,4-dimethoxyphenyl)thiazolidine-2,4-dione) with 10-fold improvement in affinity (Kd= 1.68 µM) and more than 100% increase in LE (0.45), which follows the same inhibition mode as the original hit compound (competitive to NADH).
Executive summary
- PhzS is a key enzyme in the pyocyanin biosynthesis pathway in P. aeruginosa.
- Orthogonal assays (TSA and FITC) show that fragment-like thiazolidinedione derivatives bind to PaPhzS with one-digit micromolar affinity.
- Fragment-like thiazolidinedione derivatives bind to the cofactor (NADH) binding site in PaPhzS.
- The molecular simplification optimised the ligand efficiency and affinity of the lead compound.
554.
Marcia R. Nagaoka Luciana Gomiero Felipe O. Teixeira Fernando G. Agostino José Eduardo P. Pouza Priscila Mimary Durval R. Borges Maria Kouyoumdjian 《Biochimica et Biophysica Acta (BBA)/General Subjects》2006
Bradykinin elicits an intrahepatic vascular response (IHVR) mediated by the constitutive B2 receptor (B2R). The biological effects of kinins may also be mediated by the inducible B1 receptor (B1R). Aim: To verify if the hepatic B1R expression modulates IHVR to kinins. Method: We evaluated the ability of bradykinin and B1R agonists to elicit an IHVR in normal rats and in those submitted to acute or chronic inflammatory stimuli, fibrosis, cirrhosis, or hepatic regeneration. Results: Bradykinin-induced IHVR was similar in all groups. B1R agonists did not elicit in any of them either a hypertensive or a hypotensive response. B1 receptor induction was observed in all experimental groups (Western blot), except for the acute inflammatory group. Conclusion: B1R hepatic expression did not modulate IHVR to kinins. 相似文献
555.