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91.
92.
Romain Boulho Christel Marty Yolanda Freile-Pelegrín Daniel Robledo Nathalie Bourgougnon Gilles Bedoux 《Journal of applied phycology》2017,29(5):2219-2228
Carrageenan yield, physicochemical properties, and antiviral activity of the carrageenan from Solieria chordalis (Rhodophyceae, Solieriaceae) harvested at the Brittany coast (France) were investigated. S. chordalis carrageenan was extracted by conventional and the microwave-assisted extraction (MAE) methods. The effect of different parameters during MAE extraction such as alkali concentration (0, 0.5 and 1% KOH), extraction time (10, 20, and 25 min) and temperature (90 and 105 °C) were evaluated. Native carrageenan extracted by MAE had the highest yield (29.3%) after 10 min at 90 °C. After alkali treatment, carrageenan yield ranged from 10.7 to 18.4%. No significant differences in the carrageenan yield were observed between MAE and conventional method under alkaline conditions. Chemical analysis and FTIR spectra revealed the presence of a predominant iota-carrageenan. Evaluation of the antiviral activity of S. chordalis carrageenan against HSV-1 (Herpes simplex virus type 1) showed a EC50 of the iota-carrageenans fractions in the range of 3.2 to 54.4 μg mL?1 (MOI 0.01 ID50 mL?1) without cytotoxicity in that range of concentrations. 相似文献
93.
Epichloë fungal endophytes and the formation of synthetic symbioses in Hordeeae (=Triticeae) grasses
Wayne R. SIMPSON Marty J. FAVILLE Roger A. MORAGA Warren M. WILLIAMS Michael T. MCMANUS Richard D. JOHNSON 《植物分类学报:英文版》2014,52(6):794-806
This review examines two classes of organism that live in symbiosis; grasses, and fungi. Specifically it deals with grasses of the tribe Hordeeae (formerly Triticeae) of the subfamily Poöideae and the Epichloë fungi of family Clavicipitaceae. Epichloë endophytes, particularly asexual forms, have important roles in pastoral agricultural systems in the Americas, Australia, and New Zealand. Selected strains add value to some grass-based forage systems by providing both biotic and abiotic stress resistance. The importance of cereal grasses such as wheat, barley, rye, and oats to human and animal nutrition and indeed to the foundation and maintenance of human civilization is well documented. Both organism classes, Epichloë endophytes and cereal grasses, are of great importance in their own contexts. Here, we seek to review these two classes of organism and examine the possibility of bringing them together in symbiosis with the ultimate goal of improving cereal production systems. 相似文献
94.
Pagnucco K Zanette L Clinchy M Leonard ML 《Proceedings. Biological sciences / The Royal Society》2008,275(1638):1061-1065
Nestlings of many avian brood parasites are virtuosos at mimicking host nestling vocalizations, which, like egg mimicry, presumably ensures acceptance by host parents. Having been accepted, parasitic nestlings then often exaggerate the aspects of the host's display to increase parental care. Host nestlings may, in turn, exaggerate their vocalizations to keep up with the parasite, though this possibility has not been evaluated. We experimentally parasitized song sparrow (Melospiza melodia) nests with a brown-headed cowbird (Molothrus ater) chick to evaluate how host nestlings respond. Vocalizations emitted from experimentally parasitized nests were higher in frequency, and louder, than those from unparasitized nests, consistent with the cowbird exaggerating its signalling. In response, host nestlings exaggerated the frequency and amplitude of their vocalizations, such that they resembled the cowbird's while they 'scaled back' on calls per parental provisioning bout. Sparrows in parasitized nests were fed equally often as sparrows in unparasitized nests, suggesting that exaggerating some aspects of vocalization while scaling back on others can help host nestlings confronted with a cowbird. Our results support the recently proposed hypothesis that signalling in parasitized nests involves a dynamic interaction between parasitic and host nestlings, rather than a one-way process of mimicry by the parasite. 相似文献
95.
96.
Some studies suggest that offspring might coordinate their begging displays to send a more effective brood signal, which in turn, could increase parental feeding rates. In tree swallows Tachycineta bicolor , when nestlings call together, their calls are more similar in structure than when they call alone. Here, we tested the hypothesis that call convergence enhances the overall brood signal, thus increasing parental provisioning rates. We played back similar and dissimilar calls (as measured by cross-correlation) to parents during a one-h playback period, and filmed the response of parents and nestlings. Contrary to our hypothesis, parental feeding rates did not differ in relation to call similarity. Based on these results, call similarity does not appear to function as a coordinated brood signal in tree swallows. 相似文献
97.
Valdés-Ramírez G Gutiérrez M Del Valle M Ramírez-Silva MT Fournier D Marty JL 《Biosensors & bioelectronics》2009,24(5):1103-1108
An amperometric biosensor array has been developed to resolve pesticide mixtures of dichlorvos and methylparaoxon. The biosensor array has been used in a Flow Injection system, in order to operate automatically the inhibition procedure. The sensors used were three screen-printed amperometric biosensors that incorporated three different acetylcholinesterase enzymes: the wild type from Electric eel and two different genetically modified enzymes, B1 and B394 mutants, from Drosophila melanogaster. The inhibition response triplet was modelled using an Artificial Neural Network which was trained with mixture solutions that contain dichlorvos from 10(-4) to 0.1 microM and methylparaoxon from 0.001 to 2.5 microM. This system can be considered an inhibition electronic tongue. 相似文献
98.
Naomi J. Marty Dakshinamurthy Rajalingam Alicia D. Kight Nathaniel E. Lewis Daniel Fologea Thallapuranam Krishnaswamy Suresh Kumar Ralph L. Henry Robyn L. Goforth 《The Journal of biological chemistry》2009,284(22):14891-14903
The chloroplast signal recognition particle (cpSRP) and its receptor
(cpFtsY) function in thylakoid biogenesis to target integral membrane proteins
to thylakoids. Unlike cytosolic SRP receptors in eukaryotes, cpFtsY partitions
between thylakoid membranes and the soluble stroma. Based on sequence
alignments, a membrane-binding motif identified in Escherichia coli
FtsY appears to be conserved in cpFtsY, yet whether the proposed motif is
responsible for the membrane-binding function of cpFtsY has yet to be shown
experimentally. Our studies show that a small N-terminal region in cpFtsY
stabilizes a membrane interaction critical to cpFtsY function in
cpSRP-dependent protein targeting. This membrane-binding motif is both
necessary and sufficient to direct cpFtsY and fused passenger proteins to
thylakoids. Our results demonstrate that the cpFtsY membrane-binding motif may
be functionally replaced by the corresponding region from E. coli,
confirming that the membrane-binding motif is conserved among organellar and
prokaryotic homologs. Furthermore, the capacity of cpFtsY for lipid binding
correlates with liposome-induced GTP hydrolysis stimulation. Mutations that
debilitate the membrane-binding motif in cpFtsY result in higher rates of GTP
hydrolysis, suggesting that negative regulation is provided by the intact
membrane-binding region in the absence of a bilayer. Furthermore, NMR and CD
structural studies of the N-terminal region and the analogous region in the
E. coli SRP receptor revealed a conformational change in secondary
structure that takes place upon lipid binding. These studies suggest that the
cpFtsY membrane-binding motif plays a critical role in the intramolecular
communication that regulates cpSRP receptor functions at the membrane.Proper compartmentalization of proteins relies on the ability of protein
localization pathways to transport proteins efficiently from their sites of
synthesis to their sites of function. The signal recognition particle
(SRP)2 and its
receptor function in every kingdom of life to target proteins to the
endoplasmic reticulum (eukaryotes), cytoplasmic membrane (prokaryotes), and
thylakoid membrane (chloroplasts)
(1). The targeting function of
SRP relies on a conserved 54-kDa SRP subunit (SRP54; Ffh in Escherichia
coli and cpSRP54 in chloroplasts) as well as a conserved SRP receptor
(SRα; FtsY in E. coli and cpFtsY in chloroplasts). For
cytosolic SRPs (SRP54 and Ffh), interactions with a substrate signal sequence
and an SRP RNA moiety are prerequisite for interaction with the SRP receptor
(SRα and FtsY) (2). GTP
binding and hydrolysis by both SRP54 and SRα coordinate substrate
release from SRP to the translocon and release of SRP from SRα. In
chloroplasts, cpFtsY functions along with a unique SRP (cpSRP) to
post-translationally target nuclear encoded proteins to thylakoid membranes
(3). Light-harvesting
chlorophyll a/b-binding proteins (LHCPs) imported into the
chloroplast stroma are bound by cpSRP to form a soluble targeting complex,
which directs the LHCP substrate to the thylakoid membrane translocon Alb3
(Albino3) in a GTP- and cpFtsY-dependent manner
(14,
36). Although many general
steps of SRP protein targeting seem largely conserved across evolutionary
boundaries, the nature and dynamics of the receptor appear to have
diverged.In eukaryotic systems, SRα is peripherally bound to the membrane
through association with the integral membrane subunit SRβ. In contrast,
no chloroplast or bacterial homolog of SRβ has been identified. cpFtsY
and E. coli FtsY (EcFtsY) are found partitioned between the membrane
and the stroma or cytosol, respectively. The membrane-binding capacity of
EcFtsY serves to stimulate GTPase activity and appears critical in that only
membrane-associated EcFtsY supports the release of nascent chains from SRP to
the translocon (4,
5). However, the partitioning
activity is not strictly required because EcFtsY tethered to the membrane is
functional in vivo
(37). Given the conserved
nature of partitioning among bacterial and chloroplast SRP receptors,
partitioning may play an, as of yet, unidentified role in protein targeting by
SRP. Nevertheless, differences in lipid composition between bacterial and
thylakoid membranes make it interesting to speculate that there are
mechanistic differences in membrane partitioning.Like many prokaryotic FtsY homologs (e.g. Thermus aquaticus),
cpFtsY lacks the N-terminal acidic domain (A domain) implicated in EcFtsY
membrane binding (6). Although
the highly conserved FtsY GTPase domain (NG domain) of EcFtsY
(EcFtsYNG) fails to support protein targeting, the addition of the
last A domain residue, Phe-196 of a conserved double-Phe motif
(EcFtsYNG+1), restores protein targeting in vivo
(7). In vitro studies
also show that EcFtsYNG+1 retains the capacity to bind membranes
and support integration of SRP-dependent substrates, although at significantly
reduced levels compared with full-length EcFtsY
(8). A resolved structure of
EcFtsYNG+1 suggests that the amphipathic nature of the region
containing Phe-196 plays a critical role in membrane association
(9). Furthermore, it has been
demonstrated that liposomes stimulate GTP hydrolysis rates of SRP with
EcFtsYNG+1, but not with EcFtsYNG, supporting the idea
that the A domain in its entirety is not strictly required.For cpFtsY, the necessity and functional role(s) of partitioning between a
thylakoid-bound and a soluble phase, as well as the role of N-terminal
residues in these functions, remain unknown. In addition, both the
conformational state of membrane-bound cpFtsY and EcFtsY and the mechanism
responsible for controlling membrane partitioning and altered GTPase activity
remain unclear. Because of the gain of function exhibited by
EcFtsYNG+1 and the conserved nature of the surrounding motif
(9), it seems likely that this
conserved region is necessary to support membrane binding and corresponding
functions not only in EcFtsY but also in FtsY homologs.To examine the functional role of the N-terminal region of cpFtsY, we have
utilized deletion and point mutants in assays that reconstitute cpFtsY
activities, including the cpSRP-dependent integration of LHCP. Together, our
data indicate that the conserved lipid-binding motif identified in bacterial
FtsY homologs is present in cpFtsY and is both necessary and sufficient for
thylakoid binding and critical for LHCP targeting. 相似文献
99.
Spitsbergen JM Blazer VS Bowser PR Cheng KC Cooper KR Cooper TK Frasca S Groman DB Harper CM Law JM Marty GD Smolowitz RM St Leger J Wolf DC Wolf JC 《Comparative biochemistry and physiology. Toxicology & pharmacology : CBP》2009,149(2):249-257
Utilization of finfish and aquatic invertebrates in biomedical research and as environmental sentinels has grown dramatically in recent decades. Likewise the aquaculture of finfish and invertebrates has expanded rapidly worldwide as populations of some aquatic food species and threatened or endangered aquatic species have plummeted due to overharvesting or habitat degradation. This increasing intensive culture and use of aquatic species has heightened the importance of maintaining a sophisticated understanding of pathology of various organ systems of these diverse species. Yet, except for selected species long cultivated in aquaculture, pathology databases and the workforce of highly trained pathologists lag behind those available for most laboratory animals and domestic mammalian and avian species. Several factors must change to maximize the use, understanding, and protection of important aquatic species: 1) improvements in databases of abnormalities across species; 2) standardization of diagnostic criteria for proliferative and nonproliferative lesions; and 3) more uniform and rigorous training in aquatic morphologic pathology. 相似文献
100.
Melinda L. Irwin Marty Alvarez‐Reeves Lisa Cadmus Eileen Mierzejewski Susan T. Mayne Herbert Yu Gina G. Chung Beth Jones M. Tish Knobf Loretta DiPietro 《Obesity (Silver Spring, Md.)》2009,17(8):1534-1541
Given the negative effects of a breast cancer diagnosis and its treatments on body weight and bone mass, we investigated the effects of a 6‐month randomized controlled aerobic exercise intervention vs. usual care on body composition in breast cancer survivors. Secondary aims were to examine the effects stratified by important prognostic and physiologic variables. Seventy‐five physically inactive postmenopausal breast cancer survivors were recruited through the Yale–New Haven Hospital Tumor Registry and randomly assigned to an exercise (n = 37) or usual care (n = 38) group. The exercise group participated in 150 min/week of supervised gym‐ and home‐based moderate‐intensity aerobic exercise. The usual care group was instructed to maintain their current physical activity level. Body composition was assessed at baseline and 6‐months through dual‐energy X‐ray absorptiometry (DXA) by one radiologist blinded to the intervention group of the participants. On an average, exercisers increased moderate‐intensity aerobic exercise by 129 min/week over and above baseline levels compared with 45 min/week among usual care participants (P < 0.001). Exercisers experienced decreases in percent body fat (P = 0.0022) and increases in lean mass (P = 0.047) compared with increases in body fat and decreases in lean mass in usual care participants. Bone mineral density (BMD) was also maintained among exercisers compared with a loss among usual care participants (P = 0.043). In summary, moderate‐intensity aerobic exercise, such as brisk walking, produces favorable changes in body composition that may improve breast cancer prognosis. 相似文献