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61.
Agustina Falibene Roxana Josens 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2008,194(5):491-500
Dynamics of fluid feeding has been deeply studied in insects. However, the ability to vary the nectar-intake rate depending
only on the carbohydrate deprivation has been clearly demonstrated only in Camponotus mus ants. When insect morphometry and fluid properties remain constant, changes in intake rate could only be attributed to variations
in sucking pump activity. Previous records of the electrical activity generated during feeding in C.
mus have revealed two different signal patterns: the regular (RP, frequencies: 2–5 Hz) and the irregular (IP, frequencies: 7–12 Hz). This work studies the mechanism underlying food intake-rate modulation in ants by analysing whether
these patterns are involved. Behaviour and electrical activity generated by ants at different starvation levels were analysed
during feeding on sucrose solutions. Ants were able to modulate the intake rate for a variety of sucrose concentrations (10,
40 and 60%w/w). The IP only occurred for 60% of solutions and its presence did not affect the intake rate. However, during
the RP generated under the starved state, we found frequencies up to 7.5 Hz. RP frequencies positively correlated with the
intake-rate for all sucrose concentrations. Hence, intake-rate modulation according to sugar deprivation is mainly achieved
by the ant’s ability to vary the pumping frequency. 相似文献
62.
63.
Paula Pifarré María Antonia Baltrons Istvan Földi Agustina García 《The international journal of biochemistry & cell biology》2009,41(8-9):1719-1730
NO-sensitive guanylyl cyclase (GCNO), the major NO target, is involved in important regulatory functions in the cardiovascular, gastrointestinal and central nervous systems. GCNO exists as heterodimers of α(1/2) and β1 subunits. Deletion of the obligate β1 dimerizing partner abrogates NO/cGMP signaling and shortens the life span of KO mice. Localization studies in the CNS have shown that β1 is more widespread than α subunits and in some areas is the only GCNO subunit expressed, suggesting that β1 may have GCNO-independent functions. GCNO is predominantly cytosolic, but association to membranes and other intracellular structures has been described. Here, we show localization of β1 in cytoplasm and nucleus of cells expressing α subunits and GCNO activity (astrocytes, C6 cells), as well as in cells devoid of α subunits and GCNO activity (microglia). In both cell types β1 associates peripherally to chromosomes in all phases of mitosis. Immunodepletion of β1 in C6 cells enhances chromatin condensation in an in vitro assay. Moreover, silencing β1 by siRNA induces cell cycle re-entry as determined by flow cytometry, and increases proliferation rate in a MTT-assay, whereas infection with β1-containing adenovirus has the opposite effect. These actions are independent of cGMP formation. We postulate that β1 is a multifunctional protein that regulates chromatin condensation and cell cycle progression, in addition to being an obligate monomer in functional GCNO heterodimers. 相似文献
64.
Herrera EA Riquelme RA Ebensperger G Reyes RV Ulloa CE Cabello G Krause BJ Parer JT Giussani DA Llanos AJ 《American journal of physiology. Regulatory, integrative and comparative physiology》2010,299(6):R1676-R1684
We determined whether postnatal pulmonary hypertension induced by 70% of pregnancy at high altitude (HA) persists once the offspring return to sea level and investigated pulmonary vascular mechanisms operating under these circumstances. Pregnant ewes were divided into two groups: conception, pregnancy, and delivery at low altitude (580 m, LLL) and conception at low altitude, pregnancy at HA (3,600 m) from 30% of gestation until delivery, and return to lowland (LHL). Pulmonary arterial pressure (PAP) was measured in vivo. Vascular reactivity and morphometry were assessed in small pulmonary arteries (SPA). Protein expression of vascular mediators was determined. LHL lambs had higher basal PAP and a greater increment in PAP after N(G)-nitro-L-arginine methyl ester (20.9 ± 1.1 vs. 13.7 ± 0.5 mmHg; 39.9 ± 5.0 vs. 18.3 ± 1.3 mmHg, respectively). SPA from LHL had a greater maximal contraction to K(+) (1.34 ± 0.05 vs. 1.16 ± 0.05 N/m), higher sensitivity to endothelin-1 and nitroprusside, and persistence of dilatation following blockade of soluble guanylate cyclase. The heart ratio of the right ventricle-to-left ventricle plus septum was higher in the LHL relative to LLL. The muscle area of SPA (29.3 ± 2.9 vs. 21.1 ± 1.7%) and the protein expression of endothelial nitric oxide synthase (1.7 ± 0.1 vs. 1.1 ± 0.2), phosphodiesterase (1.4 ± 0.1 vs. 0.7 ± 0.1), and Ca(2+)-activated K(+) channel (0.76 ± 0.16 vs. 0.30 ± 0.01) were greater in LHL compared with LLL lambs. In contrast, LHL had decreased heme oxygenase-1 expression (0.82 ± 0.26 vs. 2.22 ± 0.44) and carbon monoxide production (all P < 0.05). Postnatal pulmonary hypertension induced by 70% of pregnancy at HA promotes cardiopulmonary remodeling that persists at sea level. 相似文献
65.
Miguel Cantamutto Lluis Torres Alejandro Presotto Agustina Gutierrez Soledad Ureta Mónica Poverene 《Biological invasions》2010,12(3):541-551
There is a high interest to understand and recreate the invasive process of successful non-native plant invaders. The genetic
tools provide scanty information when the invasion is recent and there is gene flow among the invader and its crop relative.
The concern about the government and private companies’ responsibilities in the diffusion process and the risk of occupancy
of new areas motivated the interest in two wild annual Helianthus species naturalized in the central agricultural lands of Argentina. We used multivariate techniques and random tests to estimate
the successive steps accomplished by the plant invaders across transportation routes, following an environmental and ecological
gradient. A minimum connection tree through road distances was created considering dispersal from a unique dispersal point
for each species. The proposed tree minimized, at the same time, the environmental and the ecological distances calculated
by Euclidean and Gower indexes with abiotic and biotic habitat variables, being significantly different from random (P ≤ 0.05). Our methodology allowed the development of an approach for the best estimation of the invasion route. This could
be used to clarify the role of different agents involved in the diffusion process and to develop management strategies to
prevent the plant invasion. The migration pattern suggests that after their historical introduction, both wild species moved
in successive steps across a biotic and abiotic gradient, aided by anthropogenic activity along the road connection infrastructure.
There were no evidences of escapes from sunflower breeding stations. 相似文献
66.
Douglas Nam Chih-Wen Ni Amir Rezvan Jin Suo Klaudia Budzyn Alexander Llanos David G. Harrison Don P. Giddens Hanjoong Jo 《Journal of visualized experiments : JoVE》2010,(40)
Despite the well-known close association, direct evidence linking disturbed flow to atherogenesis has been lacking. We have recently used a modified version of carotid partial ligation methods [1,2] to show that it acutely induces low and oscillatory flow conditions, two key characteristics of disturbed flow, in the mouse common carotid artery. Using this model, we have provided direct evidence that disturbed flow indeed leads to rapid and robust atherosclerosis development in Apolipoprotein E knockout mouse [3]. We also developed a method of endothelial RNA preparation with high purity from the mouse carotid intima [3]. Using this mouse model and method, we found that partial ligation causes endothelial dysfunction in a week, followed by robust and rapid atheroma formation in two weeks in a hyperlipidemic mouse model along with features of complex lesion formation such as intraplaque neovascularization by four weeks. This rapid in vivo model and the endothelial RNA preparation method could be used to determine molecular mechanisms underlying flow-dependent regulation of vascular biology and diseases. Also, it could be used to test various therapeutic interventions targeting endothelial dysfunction and atherosclerosis in considerably reduced study duration.Download video file.(125M, mp4) 相似文献
67.
Llanos P Henriquez M Minic J Elmorjani K Marion D Riquelme G Molgó J Benoit E 《The FEBS journal》2006,273(8):1710-1722
Puroindoline-a (PIN-a) and alpha1-purothionin (alpha1-PTH), isolated from wheat endosperm of Triticum aestivum sp., have been suggested to play a role in plant defence mechanisms against phytopathogenic organisms. We investigated their ability to form pores when incorporated into giant liposomes using the patch-clamp technique. PIN-a formed cationic channels (approximately 15 pS) with the following selectivity K(+) > Na(+) > Cl(-). Also, alpha1-PTH formed channels of approximately 46 pS and 125 pS at +100 mV, the selectivity of which was Ca(2+) > Na(+) approximately K(+) > Cl(-) and Cl(-) > Na(+), respectively. In isolated mouse neuromuscular preparations, alpha1-PTH induced muscle membrane depolarization, leading to blockade of synaptic transmission and directly elicited muscle twitches. Also, alpha1-PTH caused swelling of differentiated neuroblastoma NG108-15 cells, membrane bleb formation, and disorganization of F-actin. In contrast, similar concentrations of PIN-a had no detectable effects. The cytotoxic actions of alpha1-PTH on mammalian cells may be explained by its ability to induce cationic-selective channels. 相似文献
68.
Copper is an essential trace element that can be extremely toxic in excess due to the pro-oxidant activity of copper ions. Inherited disorders of copper transport, Menkes disease (copper deficiency), and Wilson disease (copper toxicosis) are caused by mutations of two closely related Cu transporting-ATPases, and demonstrate the essentiality and potential toxicity of copper. Other copper toxicosis conditions in humans and animals have been described, but are not well understood at a molecular level. Copper homeostatic mechanisms are being discovered. One such mechanism is copper-induced trafficking of the Cu-ATPases, which allows cells to provide copper to secreted cupro-proteins but also to efflux excess copper. Oxidative damage induced by copper may be involved in the pathogenesis of neurodegenerative conditions such as Alzheimer's disease, familial amyotrophic lateral sclerosis, and prion diseases. 相似文献
69.
María Agustina Domínguez-Martín Antonio López-Lozano Jesús Diez Guadalupe Gómez-Baena Oriol Alberto Rangel-Zú?iga José Manuel García-Fernández 《PloS one》2014,9(7)
The enzyme isocitrate dehydrogenase (ICDH; EC 1.1.1.42) catalyzes the oxidative decarboxylation of isocitrate, to produce 2-oxoglutarate. The incompleteness of the tricarboxylic acids cycle in marine cyanobacteria confers a special importance to isocitrate dehydrogenase in the C/N balance, since 2-oxoglutarate can only be metabolized through the glutamine synthetase/glutamate synthase pathway. The physiological regulation of isocitrate dehydrogenase was studied in cultures of Prochlorococcus sp. strain PCC 9511, by measuring enzyme activity and concentration using the NADPH production assay and Western blotting, respectively. The enzyme activity showed little changes under nitrogen or phosphorus starvation, or upon addition of the inhibitors DCMU, DBMIB and MSX. Azaserine, an inhibitor of glutamate synthase, induced clear increases in the isocitrate dehydrogenase activity and icd gene expression after 24 h, and also in the 2-oxoglutarate concentration. Iron starvation had the most significant effect, inducing a complete loss of isocitrate dehydrogenase activity, possibly mediated by a process of oxidative inactivation, while its concentration was unaffected. Our results suggest that isocitrate dehydrogenase responds to changes in the intracellular concentration of 2-oxoglutarate and to the redox status of the cells in Prochlorococcus. 相似文献
70.