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41.
42.
de Medeiros Bastos G Brenner RH Willke FW Neves JP de Oliveira JF Bragança JF Machado SA Porciúncula PM Gonçalves PB 《Theriogenology》2004,62(5):847-853
The objective was to develop a program for inducing estrus (followed by insemination) of suckled beef cows under nutritional stress (poor body condition). A total of 123 cows, from 60 to 75 days postpartum, were classified according to their body condition score (BCS; range from 1 to 5, in increments of 0.5) and allocated into two groups. On Day 0 (without regard to stage of the estrous cycle), cows (n = 59) in the hormone induction (HI) treatment group were given an intravaginal device (IVD) containing 250 mg of medroxiprogesterone acetate (MAP) and an i.m. injection of 2.5 mg estradiol benzoate (EB). On Day 6, these cows were given 500 IU eCG i.m. and calves were weaned for 96 h. The IVD were removed on Day 7. Cows detected in estrus by 45 h after IVD removal were inseminated 12 h after standing estrus; cows not in estrus by 45 h after IVD removal received an i.m. injection of 100 microg gonadorelin (GnRH) and were inseminated 16-18 h later. In the control group (C), cows (n = 64) only had their calves weaned at Day 6 (for 96 h), with estrus detection and AI from Days 6 to 11. Overall, the BCS ranged from 2.0 to 3.0. In the treatment group, estrus and pregnancy rates in cows with BCS 2.0 (20 and 30%, respectively) was lower (P < 0.05) than those with BCS 3.0 (50 and 66.6%, respectively), but did not differ (P > 0.05) from BCS 2.5 (23.3 and 47.6%). In C group, only 2 of 66 cows were detected in estrus and bred (neither was pregnant). In conclusion, the program for induction of ovulation using MAP, EB, eCG and GnRH increased the pregnancy rate in beef cows in poor body condition, enabling AI to be done in a 63-h interval. 相似文献
43.
We investigated the mode of action of aureocin A53 on living bacterial cells and model membranes. Aureocin A53 acted bactericidally against Staphylococcus simulans 22, with >90% of the cells killed within a few minutes. Cell death was followed by lysis, as indicated by a clearing of the cell suspension and Gram staining. Aureocin A53 rapidly dissipated the membrane potential and simultaneously stopped biosynthesis of DNA, polysaccharides, and protein. Aureocin A53 induced a rapid release of preaccumulated glutamate and Rb(+). Experiments on model membranes demonstrated that aureocin A53 provoked significant leakage of carboxyfluorescein (CF) exclusively from acidic liposomes but only at relatively high concentrations (0.5 to 8 mol%). Thus, the bactericidal activity of aureocin A53 derives from membrane permeation via generalized membrane destruction rather than by formation of discrete pores within membranes. Tryptophan emission fluorescence spectroscopy demonstrated interaction of aureocin A53 with both acidic and neutral membranes, as indicated by similar blue shifts. Since there was no significant aureocin A53-induced CF leakage from neutral liposomes, its appears that the peptide does interact with neutral lipids without provoking membrane damage. 相似文献
44.
Cellular prion protein transduces neuroprotective signals 总被引:27,自引:0,他引:27
Chiarini LB Freitas AR Zanata SM Brentani RR Martins VR Linden R 《The EMBO journal》2002,21(13):3317-3326
To test for a role for the cellular prion protein (PrP(c)) in cell death, we used a PrP(c)-binding peptide. Retinal explants from neonatal rats or mice were kept in vitro for 24 h, and anisomycin (ANI) was used to induce apoptosis. The peptide activated both cAMP/protein kinase A (PKA) and Erk pathways, and partially prevented cell death induced by ANI in explants from wild-type rodents, but not from PrP(c)-null mice. Neuroprotection was abolished by treatment with phosphatidylinositol-specific phospholipase C, with human peptide 106-126, with certain antibodies to PrP(c) or with a PKA inhibitor, but not with a MEK/Erk inhibitor. In contrast, antibodies to PrP(c) that increased cAMP also induced neuroprotection. Thus, engagement of PrP(c) transduces neuroprotective signals through a cAMP/PKA-dependent pathway. PrP(c) may function as a trophic receptor, the activation of which leads to a neuroprotective state. 相似文献
45.
Coordinated and distinct roles for IFN-alpha beta,IL-12, and IL-15 regulation of NK cell responses to viral infection 总被引:13,自引:0,他引:13
Nguyen KB Salazar-Mather TP Dalod MY Van Deusen JB Wei XQ Liew FY Caligiuri MA Durbin JE Biron CA 《Journal of immunology (Baltimore, Md. : 1950)》2002,169(8):4279-4287
NK cell cytotoxicity, IFN-gamma expression, proliferation, and accumulation are rapidly induced after murine CMV infections. Under these conditions, the responses were shown to be elicited in overlapping populations. Nevertheless, there were distinct signaling molecule requirements for induction of functions within the subsets. IL-12/STAT4 was critical for NK cell IFN-gamma expression, whereas IFN-alphabeta/STAT1 were required for induction of cytotoxicity. The accumulation/survival of proliferating NK cells was STAT4-independent but required IFN-alphabeta/STAT1 induction of IL-15. Taken together, the results define the coordinated interactions between the cytokines IFN-alphabeta, IL-12, and IL-15 for activation of protective NK cell responses during viral infections, and emphasize these factors' nonredundant functions under in vivo physiological conditions. 相似文献
46.
The isolation of ent-kaur-16-en-19-oic acid (1) from the leaves and bark of Annona glabra and its determination by reversed-phase HPLC with a photodiode array detector is described. The results indicate that 1 accumulates in the bark of the plant with only very low concentrations in the leaves. Levels of 1 varied throughout the year being highest for bark and leaves in the autumn (5.29 +/- 0.23 and 0.27 +/- 0.01 mg/g dry weight, respectively) and lowest in the spring for bark and in the winter for leaves (4.00 +/- 0.25 and 0.11 +/- 0.01 mg/g dry weight, respectively). 相似文献
47.
Fernandes E Carvalho F Silva AM Santos CM Pinto DC Cavaleiro JA Bastos Mde L 《Journal of enzyme inhibition and medicinal chemistry》2002,17(1):45-48
The purpose of this study was the evaluation of the xanthine oxidase (XO) inhibition produced by some synthetic 2-styrylchromones. Ten polyhydroxylated derivatives with several substitution patterns were synthesised, and these and a positive control, allopurinol, were tested for their effects on XO activity by measuring the formation of uric acid from xanthine. The synthesised 2-styrylchromones inhibited xanthine oxidase in a concentration-dependent and non-competitive manner. Some IC50 values found were as low as 0.55 microM, which, by comparison with the IC50 found for allopurinol (5.43 microM), indicates promising new inhibitors. Those 2-styrylchromones found to be potent XO inhibitors should be further evaluated as potential agents for the treatment of pathologies related to the enzyme's activity, as is the case of gout, ischaemia/reperfusion damage, hypertension, hepatitis and cancer. 相似文献
48.
Santos AL Souto-Padrón T Alviano CS Lopes AH Soares RM Meyer-Fernandes JR 《Archives of biochemistry and biophysics》2002,397(2):191-198
The secreted form of mouse meprin A is a homooligomer of meprin alpha subunits that contain a prosequence, a catalytic domain, and three domains designated as MAM (meprin, A5 protein, receptor protein-tyrosine phosphatase mu), MATH (meprin and TRAF homology), and AM (AfterMath). Previous studies indicated that wild-type mouse meprin alpha is predominantly a secreted protein, while the MAM deletion mutant (DeltaMAM) is degraded intracellularly. The work herein indicates that the DeltaMAM mutant is ubiquitinated and degraded via the proteasomal pathway. Both wild-type meprin alpha and the DeltaMAM mutant interact with the molecular chaperones calnexin and calreticulin in the endoplasmic reticulum. The interactions of the chaperones with the DeltaMAM mutant were significantly prolonged in the presence of lactacystin, a specific inhibitor of the proteasome, whereas those with the wild type were not affected by this inhibitor. Trimming of the Asn-linked core oligosaccharides of meprin subunits was required for interactions with the chaperones. The data indicated that folding of the wild-type protein was accelerated by chaperones, whereas the rate of dimerization was unaffected. Thus, calnexin and calreticulin are intimately involved in the correct folding and transport of meprin to the plasma membrane, as well as in retrograde transport of the DeltaMAM mutant to the ubiquitin-dependent proteasomal degradative pathway in the cytosol. 相似文献
49.
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