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991.
He X Azarov I Jeffers A Presley T Richardson J King SB Gladwin MT Kim-Shapiro DB 《Free radical biology & medicine》2008,44(7):1420-1432
Release of hemoglobin from the erythrocyte during intravascular hemolysis contributes to the pathology of a variety of diseased states. This effect is partially due to the enhanced ability of cell-free plasma hemoglobin, which is primarily found in the ferrous, oxygenated state, to scavenge nitric oxide. Oxidation of the cell-free hemoglobin to methemoglobin, which does not effectively scavenge nitric oxide, using inhaled nitric oxide has been shown to be effective in limiting pulmonary and systemic vasoconstriction. However, the ferric heme species may be reduced back to ferrous hemoglobin in plasma and has the potential to drive injurious redox chemistry. We propose that compounds that selectively convert cell-free hemoglobin to ferric, and ideally iron-nitrosylated heme species that do not actively scavenge nitric oxide, would effectively treat intravascular hemolysis. We show here that nitroxyl generated by Angeli's salt (sodium alpha-oxyhyponitrite, Na2N2O3) preferentially reacts with cell-free hemoglobin compared to that encapsulated in the red blood cell under physiologically relevant conditions. Nitroxyl oxidizes oxygenated ferrous hemoglobin to methemoglobin and can convert the methemoglobin to a more stable, less toxic species, iron-nitrosyl hemoglobin. These results support the notion that Angeli's salt or a similar compound could be used to effectively treat conditions associated with intravascular hemolysis. 相似文献
992.
Animals experiencing a trade-off between predation risk and resource acquisition must accurately predict ambient levels of
predation risk to maximize fitness. We measure this trade-off explicitly in larvae of the damselfly Enallagma antennatum, comparing consumption rates in the presence of chemical cues from predators and injured prey. Damselflies distinguished among
types of chemical cues based on species of prey injured or eaten. Injured coexisting heterospecific and unknown heterospecific
chemical cues did not reduce foraging relative to starved predator cues, while cues arising from predators eating a coexisting
heterospecific did decrease foraging. This study shows a cost in terms of reduced foraging in response to chemical cues and
further defines the ability of prey to respond discerningly to chemical cues. 相似文献
993.
Routing nitrate through backwaters of regulated floodplain rivers to increase retention could decrease loading to nitrogen
(N)-sensitive coastal regions. Sediment core determinations of N flux were combined with inflow–outflow fluxes to develop
mass balance approximations of N uptake and transformations in a flow-controlled backwater of the Upper Mississippi River
(USA). Inflow was the dominant nitrate source (>95%) versus nitrification and varied as a function of source water concentration
since flow was constant. Nitrate uptake length increased linearly, while uptake velocity decreased linearly, with increasing
inflow concentration to 2 mg l−1, indicating limitation of N uptake by loading. N saturation at higher inflow concentration coincided with maximum uptake
capacity, 40% uptake efficiency, and an uptake length 2 times greater than the length of the backwater. Nitrate diffusion
and denitrification in sediment accounted for 27% of the backwater nitrate retention, indicating that assimilation by other
biota or denitrification on other substrates were the dominant uptake mechanisms. Ammonium export from the backwater was driven
by diffusive efflux from the sediment. Ammonium increased from near zero at the inflow to a maximum mid-lake, then declined
slightly toward the outflow due to uptake during transport. Ammonium export was small compared to nitrate retention.
Handling editor: J. Padisak 相似文献
994.
We have functionally produced the outer membrane cytochrome OmcA from Shewanella oneidensis in Escherichia coli. Substrate accessibility experiments indicate that OmcA is surface exposed in an E. coli B strain but not in a K-12 strain. We show that a functional type II secretion system is required for surface localization. 相似文献
995.
De Yang Qian Chen Joost J. Oppenheim Pentti Kuusela John W. Taylor David Wade 《Letters in Peptide Science》2003,10(2):99-110
Summary Several naturally occurring antimicrobial peptides, from mammals and insects, have previously been shown to be chemotactic
for human inflammatory cells. Based on this evidence, ten synthetic analogs of naturally occurring antibiotic peptides from
the skin secretions of three species of Ranid frogs and the venom of one species of Vespid wasp (i.e., T/V-like peptides)
were tested for their abilities to induce migration of human neutrophils and monocytes. These included temporin A (TA fromRana temporaria), temporin 1P (T1P fromR. pipens), ranateurin 6 (Rana-6 fromR. catesbeiana)], three TA analogs [all D-amino acids (D-TA), reversed sequence (Rev-TA), and Pro3→Gly (G3-TA)], two frog skin-related T/V-like
peptide consensus sequences (I4S10-Con and I4G10-Con), VesCP-M (VCP-M fromVespa mandarinia), and a hybrid peptide composed of portions of the insect antibiotic peptide, cecropin A (CA), and TA (CATA). TA, T1P, Rana-6,
VCP-M, G3-TA, I4S10-Con, I4G10-Con, and CATA all induced cell migration at micromolar concentrations. D-TA and Rev-TA did
not induce cell migration, suggesting that this process involves a chiral interaction, such as receptor binding, and also
depends on the order of amino acids within TA. The results demonstrate, for the first time, that certain T/V-like antibiotic
peptides are capable of inducing chemotaxis of human phagocytes and suggest that these peptides are multifunctional molecules
with antimicrobial, hemolytic, and chemotactic capabilities. 相似文献
996.
Molly A. Bower Mare Cudic William Campbell John D. Wade Laszlo Otvos 《International journal of peptide research and therapeutics》2003,10(5-6):463-473
Analogs of pyrrhocoricin, a proline-rich antibacterial peptide with a potential therapeutic use, show multiple actions on
bacterial cells. We used a dual-fluorochrome membrane viability assay to provide evidence that the lead drug candidate, Pip-pyrr-MeArg
dimer derivative, kills bacteria better than the native peptide due to an improved activity on bacterial membranes. This assay
was also instrumental in documenting that activity on bacterial membranes and toxicity to human cells can be correlated, and
the predominant mode of action can be changed from intracellular DnaK inhibition to membrane disintegration. Similar analyses
with an alanine-scan on pyrrhocoricin identified Lys3 as a crucial player to interaction with bacterial membranes, three prolines
in mid-chain position as being responsible for maintaining structural integrity and Asp2, Tyr6, Leu7, and Arg9 as putative
contact points to the D-E helix of the bacterial target protein DnaK. 相似文献
997.
Yang De Chen Qian Oppenheim Joost J. Kuusela Pentti Taylor John W. Wade David 《International journal of peptide research and therapeutics》2003,10(2):99-110
Summary Several naturally occurring antimicrobial peptides, from mammals and insects, have previously been shown to be chemotactic
for human inflammatory cells. Based on this evidence, ten synthetic analogs of naturally occurring antibiotic peptides from
the skin secretions of three species of Ranid frogs and the venom of one species of Vespid wasp (i.e., T/V-like peptides)
were tested for their abilities to induce migration of human neutrophils and monocytes. These included temporin A (TA fromRana temporaria), temporin 1P (T1P fromR. pipens), ranateurin 6 (Rana-6 fromR. catesbeiana)], three TA analogs [all D-amino acids (D-TA), reversed sequence (Rev-TA), and Pro3→Gly (G3-TA)], two frog skin-related T/V-like
peptide consensus sequences (I4S10-Con and I4G10-Con), VesCP-M (VCP-M fromVespa mandarinia), and a hybrid peptide composed of portions of the insect antibiotic peptide, cecropin A (CA), and TA (CATA). TA, T1P, Rana-6,
VCP-M, G3-TA, I4S10-Con, I4G10-Con, and CATA all induced cell migration at micromolar concentrations. D-TA and Rev-TA did
not induce cell migration, suggesting that this process involves a chiral interaction, such as receptor binding, and also
depends on the order of amino acids within TA. The results demonstrate, for the first time, that certain T/V-like antibiotic
peptides are capable of inducing chemotaxis of human phagocytes and suggest that these peptides are multifunctional molecules
with antimicrobial, hemolytic, and chemotactic capabilities. 相似文献
998.
A number of explanations have been advanced to account for the increased frequency and intensity at which jellyfish (pelagic
cnidarians and ctenophores) blooms are being observed, most of which have been locally directed. Here, we investigate seasonal
and inter-annual patterns in abundance and distribution of jellyfish in the North Atlantic Ocean to determine if there have
been any system-wide changes over the period 1946–2005, by analysing records of the presence of coelenterates from the Continuous
Plankton Recorder (CPR) survey. Peaks in jellyfish abundance are strongly seasonal in both oceanic and shelf areas: oceanic
populations have a mid-year peak that is more closely related to peaks in phyto- and zooplankton, whilst the later peak of
shelf populations mirrors changes in SST and reflects processes of advection and aggregation. There have been large amplitude
cycles in the abundance of oceanic and shelf jellyfish (although not synchronous) over the last 60 years, with a pronounced
synchronous increase in abundance in both areas over the last 10 years. Inter-annual variations in jellyfish abundance in
oceanic areas are related to zooplankton abundance and temperature changes, but not to the North Atlantic Oscillation or to
a chlorophyll index. The long-term inter-annual abundance of jellyfish on the shelf could not be explained by any environmental
variables investigated. As multi-decadal cycles and more recent increase in jellyfish were obvious in both oceanic and shelf
areas, we conclude that these are likely to reflect an underlying climatic signal (and bottom-up control) rather than any
change in fishing pressure (top-down control). Our results also highlight the role of the CPR data in investigating long-term
changes in jellyfish, and suggest that the cnidarians sampled by the CPR are more likely to be holoplanktic hydrozoans and
not the much larger meroplanktic scyphozoans as has been suggested previously.
Guest editors: K. A. Pitt & J. E. Purcell
Jellyfish Blooms: Causes, Consequences, and Recent Advances 相似文献
999.
U. Izagirre E. Angulo S. C. Wade I. ap Gwynn I. Marigómez 《Cell and tissue research》2009,335(2):441-454
In environmental toxicology, the most commonly used techniques used to visualise lysosomes in order to determine their responses
to pollutants (LSC test: lysosomal structural changes test; LMS test: lysosomal membrane stability test) are based on the
histochemical application of lysosomal marker enzymes. In mussel digestive cells, the marker enzymes used are β-glucuronidase
(β-Gus) and hexosaminidase (Hex). The present work has been aimed at determining the distribution of these lysosomal marker
enzymes in the various compartments of the endo-lysosomal system (ELS) of mussel digestive cells and at exploring whether
intercellular transfer of lysosomal enzymes occurs between digestive and basophilic cells. Immunogold cytochemistry has allowed
us to conclude that β-Gus is present in every compartment of the digestive cell ELS, whereas Hex is not so widely distributed.
Moreover, Hex is intimately linked to the lysosomal membrane, whereas β-Gus appears to be not necessarily membrane-bound.
Therefore, two populations of heterolysosomes with different enzyme load and membrane stability have been distinguished in
the digestive cell. In addition, heterolysosomes of different electron density have been commonly observed merging together
by contact; we suggest that some might act as storage granules for lysosomal enzymes. On the other hand, β-Gus seems to be
released to the digestive alveolar lumen in secretory lysosomes produced by basophilic cells and endocytosed by digestive
cells. Regarding the implications of the present study on the interpretation of lysosomal biomarkers, we conclude that β-Gus,
but not Hex, histochemistry provides an appropriate marker for the LSC test and that, although both lysosomal marker enzymes
can be employed in the LMS test, different values would be obtained depending on the marker enzyme employed.
This study was funded by the University of the Basque Country through a grant to Consolidated Research Groups. U.I. is a recipient
of a pre-doctoral fellowship from the Basque Government. 相似文献
1000.
Oscar Godoy David M. Richardson Fernando Valladares Pilar Castro-D��ez 《Annals of botany》2009,103(3):485-494