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991.
Zsolt Tokaji Elfrieda Fodor Andrea Szabó-Nagy Tibor Páli 《European biophysics journal : EBJ》2010,39(12):1605-1611
The light-catalysed reaction of hydroxylamine (HA) with retinal is one of the basic features of bacteriorhodopsin (BR). Surprisingly, according to recent results, neither the photocycle and proton pumping of BR, nor the trans–cis isomerisation of retinal is prerequisite for photobleaching of BR in the presence of HA. How, then, is the accessibility of retinal to HA enhanced on illumination? We studied whether local thermal denaturation of BR, proposed recently, could provide an explanation for HA-promoted bleaching. According to our results, HA does not alter the absorption spectrum and the photocycle kinetics of BR substantially at room temperature, even at molar concentrations, but grossly affects the temperature of thermal denaturation. At pH 7, the presence of 0.5 M HA reduces the denaturation temperature from 100°C to as low as 72°C. The decrease is proportional to the logarithm of the HA concentration over more than three orders of magnitude, and even 0.5 mM HA has a significant effect. In addition, photobleaching becomes considerably faster with increasing temperature in the presence of HA, it takes a few seconds at 50–60°C. Our results suggest that photobleaching of BR in the presence of HA can be explained by overall destabilisation of the structure of the protein and local thermal denaturation that has already accounted for the photobleaching of the HA-free BR at elevated temperatures. These results further support the importance of thermooptic effects in protein photoreactions and identify HA as a thermal destabiliser of BR. 相似文献
992.
Characterization of the novel antifungal chitosanase PgChP and the encoding gene from Penicillium chrysogenum 总被引:1,自引:0,他引:1
Andrea Rodríguez-Martín Raquel Acosta Susan Liddell Félix Núñez María José Benito Miguel A. Asensio 《Applied microbiology and biotechnology》2010,88(2):519-528
The protein PgChP is a new chitosanase produced by Penicillium chrysogenum AS51D that showed antifungal activity against toxigenic molds. Two isoforms were found by SDS-PAGE in the purified extract
of PgChP. After enzymatic deglycosylation, only the smaller isoform was observed by SDS-PAGE. Identical amino acid sequences
were obtained from the two isoforms. Analysis of the molecular mass by electrospray ionization-mass spectrometry revealed
six major peaks from 30 to 31 kDa that are related to different levels of glycosylation. The pgchp gene has 1,146 bp including four introns and an open reading frame encoding a protein of 304 amino acids. The translated
open reading frame has a predicted mass of 32 kDa, with the first 21 amino acids comprising a signal peptide. Two N glycosylation
consensus sequences are present in the protein sequence. The deduced sequence showed high identity with fungal chitosanases.
A high level of catalytic activity on chitosan was observed. PgChP is the first chitosanase described from P. chrysogenum. Given that enzymes produced by this mold species are granted generally recognized as safe status, PgChP could be used as
a food preservative against toxigenic molds and to obtain chitosan oligomers for food additives and nutraceuticals. 相似文献
993.
Andrea Bshary Redouan Bshary 《Ethology : formerly Zeitschrift fur Tierpsychologie》2010,116(8):681-690
The conditions under which humans benefit from contributing to a public good have attracted great interest; in particular the potential role of punishment of cheaters is hotly debated. In contrast, similar studies on other animals are lacking. In this study, we describe for the first time how the course of interactions between parasitic sabre‐tooth blennies (the cheaters) and their reef fish victims can be used to study both punishment and the emergence of public goods. Sabre tooth blennies (Plagiotremus sp.) sneak up from behind to bite off small pieces of scales and/or mucus from other fish. Victims regularly show spontaneous aggression as well as aggressive responses to blenny attacks. In a between species comparison, we tested how the probability of chasing a blenny is affected by (1) the option of avoiding interactions with a blenny by avoiding its small territory, and (2) variation in local abundance of conspecifics. We found that resident victim species are more aggressive towards blennies than visiting species. This difference persisted when we controlled for victim size and territoriality, suggesting that it is the enforced repeated game structure that causes residents to chase blennies. In residents, we also found a negative correlation between aggression towards blennies and local abundance, which suggests that the benefits of chasing are diluted with increasing local abundance. We discuss the implication of these results for future studies. 相似文献
994.
Andrea Marino 《Ethology : formerly Zeitschrift fur Tierpsychologie》2010,116(11):999-1010
According to current theory, anti‐predator benefits promote group formation in open‐dwelling ungulates. An inverse relationship between vigilance effort and group size has been documented frequently and thought to reflect the consequent decrease in perceived predation risk as group size increases. In contrast, competition costs are supposed to set the upper limit to the number of individuals that can forage together. As anti‐predator behavior is no longer functional in the absence of predation and competition costs might be affected by resource distribution, the net benefit of aggregation will depend on the particular combination of predation risk and habitat structure experienced by the individual. To test this hypothesis, group‐size effects on female time allocation and within‐group aggression rate were compared between two guanaco populations exposed to contrasting levels of puma predation. Habitat structure within both sites consisted of mosaics of shrublands and grasslands, and group‐size effects were also compared between these habitat types. Females under predation risk showed a strong reduction in vigilance as the number of adults in the group increased, whereas females from the predator‐free population showed overall low levels of vigilance, regardless of group size. These results emphasize the anti‐predator significance of the group‐size effect on female vigilance, as well as guanaco plasticity to adjust time allocation to local conditions. On the other hand, within‐group aggression rate increased with the number of adults in the group. Aggression rate was almost null within groups located in grasslands but was significantly higher in shrublands, regardless of predation risk, suggesting that the more heterogeneous distribution of shrubs increases the interference competition level. These results strengthen the notion of predation pressure and habitat structure as major determinants of the balance between costs and benefits of group living, and highlight the potential of individual behavioral patterns to make qualitative predictions about group‐size variation within territorial ungulates. 相似文献
995.
Balázs Gulyás Damian Brockschnieder Sangram Nag Elena Pavlova Péter Kása Zsuzsa Beliczai Ádám Légrádi Károly Gulya Andrea Thiele Thomas Dyrks Christer Halldin 《Neurochemistry international》2010,56(6-7):789-798
Earlier post-mortem histological and autoradiographic studies have indicated a reduction of cell numbers in the locus coeruleus (LC) and a corresponding decrease in norepinephrine transporter (NET) in brains obtained from Alzheimer's disease (AD) patients as compared to age-matched healthy controls. In order to test the hypothesis that the regional decrease of NET is a disease specific biomarker in AD and as such, it can be used in PET imaging studies for diagnostic considerations, regional differences in the density of NET in various anatomical structures were measured in whole hemisphere human brain slices obtained from AD patients and age-matched control subjects in a series of autoradiographic experiments using the novel selective PET radioligand for NET (S,S)-[18F]FMeNER-D2. (S,S)-[18F]FMeNER-D2 appears to be a useful imaging biomarker for quantifying the density of NET in various brain structures, including the LC and the thalamus wherein the highest densities are found in physiological conditions. In AD significant decreases of NET densities can be demonstrated with the radioligand in both structures as compared to age-matched controls. The decreases in AD correlate with the progress of the disease as indicated by Braak grades. As the size of the LC is below the spatial resolution of the PET scanners, but the size of the thalamus can be detected with appropriate spatial accuracy in advanced scanners, the present findings confirm our earlier observations with PET that the in vivo imaging of NET with (S,S)-[18F]FMeNER-D2 in the thalamus is viable. Nevertheless, further studies are warranted to assess the usefulness of such an imaging approach for the early detection of changes in thalamic NET densities as a disease-specific biomarker and the possible use of (S,S)-[18F]FMeNER-D2 as a molecular imaging biomarker in AD. 相似文献
996.
Asha Nair Manuela Simonetti Elsa Fabbretti Andrea Nistri 《Cellular and molecular neurobiology》2010,30(4):505-509
Cdk5 is an endogenous kinase activated by the neuronal-specific protein p35 and implicated in multiple neuronal functions,
including modulation of certain pain responses. We investigated whether Cdk5 could regulate ATP-gated P2X3 receptors that are members of the family of membrane proteins expressed by sensory neurons to transduce nociception in baseline
and chronic pain. To study the potential P2X3 receptor modulation by Cdk5, we co-transfected rat P2X3 receptors and Cdk5 into HEK cells and observed increased P2X3 receptor serine phosphorylation together with downregulation of receptor currents only when these genes were transfected
together with the gene of the Cdk5 activator p35. The changes in receptor responses were limited to depressed current amplitude
as desensitization and recovery were not altered. Transfection of p35 with P2X3 similarly downregulated receptor responses, suggesting that this phenomenon could be observed even with constitutive Cdk5.
The present data indicate a novel target to express the action of Cdk5 on membrane proteins involved in pain perception. 相似文献
997.
998.
Emanuela Viggiano Marcellino Monda Alessandro Viggiano Andrea Viggiano Caterina Aurilio Bruno De Luca 《Molecular and cellular biochemistry》2010,339(1-2):149-154
Previous studies have demonstrated that there is an increase in oxidative stress in the cerebral cortex of rats after repeated painful stimulation and that long-lasting pain increases the production of superoxide ion (O2 ?), nitric oxide and peroxynitrite due to the activation of AMPA and NMDA receptors. The purpose of the present study was to evaluate the possible role of O2 ? in the transmission of oro-facial pain. Formaldehyde 1% was injected subcutaneously into one vibrissal pad of adult male Sprague-Dawley rats as a model of persistent pain, then O2 ? production and superoxide dismutase (SOD) activity were evaluated in the left and right spinal trigeminal nuclei. O2 ? production was revealed using dihidroetidium (DHE) injected at 10 or 45 min after the formalin injection in conscious or anaesthetized rats. A histochemical assay for SOD was performed to evaluate the activity of SOD at 10 min after the formalin injection. The results showed a significant increase in O2 ? production in the homolateral nucleus at 45 min. However, there was no significant difference between the two sides at 10 min after the formalin injection. No significant difference was observed in SOD activity between the two sides of the spinal trigeminal nucleus. This study demonstrated that there is an increased production of O2 ? in the second phase but not in the first phase of the formalin test; thus O2 ? is involved in pain induced by inflammation, but not in acute pain. 相似文献
999.
Ákos Boros Ildikó Somogyi Péter Engelmann Andrea Lubics Dóra Reglodi Edit Pollák László Molnár 《Cell and tissue research》2010,339(3):649-653
Pituitary adenylate cyclase activating polypeptide (PACAP)-like molecules have been shown to be present in cocoon albumin
and in Eisenia fetida embryos at an early developmental stage (E1) by immunocytochemistry and radioimmunoassay. Here, we focus on detecting the
stage at which PAC1 receptor (PAC1R)-like immunoreactivity first appears in germinal layers and structures, e.g., various
parts of the central nervous system (CNS), in developing earthworm embryos. PAC1R-like immunoreactivity was revealed by Western
blot and Far Western blot as early as the E2 developmental stage, occurring in the ectoderm and later in specific neurons
of the developing CNS. Labeled CNS neurons were first seen in the supraesophageal ganglion (brain) and subsequently in the
subesophageal and ventral nerve cord ganglia. Ultrastructurally, PAC1Rs were located mainly on plasma membranes and intracellular
membranes, especially on cisternae of the endoplasmic reticulum. Therefore, PACAP-like compounds probably influence the differentiation
of germinal layers (at least the ectoderm) and of some neurons and might act as signaling molecules during earthworm embryonic
development. 相似文献
1000.
Belli Mauro Ottolenghi Andrea Weiss Wolfgang 《Radiation and environmental biophysics》2010,49(3):463-468
Health effects of exposures at low doses and/or low dose rates are recognized as requiring intensive research activity to
answer several questions. To address these issues at a strategic level in Europe, with the perspective of integrating national
and EC efforts (in particular those within the Euratom research programmes), a “European High Level and Expert Group (HLEG)
on low dose risk research” was formed and carried out its work during 2008. The Group produced a report published by the European
Commission in 2009 and available on the website . The more important research issues identified by the HLEG were as follows: (a) the shape of dose–response for cancer; (b)
the tissue sensitivities for cancer induction; (c) the individual variability in cancer risk; (d) the effects of radiation
quality (type); (e) the risks from internal radiation exposure; and (f) the risks of, and dose response relationships for,
non-cancer diseases. In this paper, the radiation quality issues are especially considered, since they are closely linked
to health problems and related radioprotection in space and in emerging radiotherapeutic techniques (i.e., hadrontherapy).
The peculiar features of low-fluence, high-LET radiation exposures can question in particular the validity of the radiation-weighting
factor (w
R
) approach. Specific strategies are therefore needed to assess such risks. A multi-scale/systems biology approach, based on
mechanistic studies coordinated with molecular-epidemiological studies, is considered essential to elucidate differences and
similarities between specific effects of low- and high-LET radiation. 相似文献