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101.
The abundance of newly settled recruits of coral reef fishes was monitored at a total of 11 sites at two islands and two coastal
locations in the central Philippines for a 20-month period (February 2008 to September 2009) that included two monsoon cycles.
Recruitment occurred throughout the year. Most of the abundant species exhibited protracted recruitment seasons. This confirms
the expectation of extended breeding of reef fishes at lower latitudes. The annual pattern of recruitment of reef fishes as
a group was predictable. Annual fluctuations of sea surface temperature and wind strength largely explained the pattern. Rainfall,
however, did not significantly influence the pattern of recruitment. Peaks in density and species richness of recruits occurred
during the southwest monsoon and the second inter-monsoonal period of the year (July to October) when temperatures were highest
and when most of the sites were sheltered from winds or when winds were weak. Conversely, lowest density and species richness
were observed during the northeast monsoon (November to March) when temperatures were lowest and most sites were exposed to
winds. The same pattern could also be seen in the recruitment of both damselfishes (Pomacentridae) and wrasses (Labridae),
notwithstanding a tenfold difference in abundance of recruits between the two families. The pattern was fairly consistent
across most sites, among most of the species that were examined, and between the 2 years that were sampled. This study is
one of the few to provide insights into the influence of environmental factors on the recruitment patterns of fishes on Indo-Pacific
coral reefs situated at lower latitudes. 相似文献
102.
Bettina Wahl Debora Reichmann Dimitri Niks Nina Krompholz Antje Havemeyer Bernd Clement Tania Messerschmidt Martin Rothkegel Harald Biester Russ Hille Ralf R. Mendel Florian Bittner 《The Journal of biological chemistry》2010,285(48):37847-37859
The mitochondrial amidoxime reducing component mARC is a newly discovered molybdenum enzyme that is presumed to form the catalytical part of a three-component enzyme system, consisting of mARC, heme/cytochrome b5, and NADH/FAD-dependent cytochrome b5 reductase. mARC proteins share a significant degree of homology to the molybdenum cofactor-binding domain of eukaryotic molybdenum cofactor sulfurase proteins, the latter catalyzing the post-translational activation of aldehyde oxidase and xanthine oxidoreductase. The human genome harbors two mARC genes, referred to as hmARC-1/MOSC-1 and hmARC-2/MOSC-2, which are organized in a tandem arrangement on chromosome 1. Recombinant expression of hmARC-1 and hmARC-2 proteins in Escherichia coli reveals that both proteins are monomeric in their active forms, which is in contrast to all other eukaryotic molybdenum enzymes that act as homo- or heterodimers. Both hmARC-1 and hmARC-2 catalyze the N-reduction of a variety of N-hydroxylated substrates such as N-hydroxy-cytosine, albeit with different specificities. Reconstitution of active molybdenum cofactor onto recombinant hmARC-1 and hmARC-2 proteins in the absence of sulfur indicates that mARC proteins do not belong to the xanthine oxidase family of molybdenum enzymes. Moreover, they also appear to be different from the sulfite oxidase family, because no cysteine residue could be identified as a putative ligand of the molybdenum atom. This suggests that the hmARC proteins and sulfurase represent members of a new family of molybdenum enzymes. 相似文献
103.
Simon Duval Joanne M. Santini Wolfgang Nitschke Russ Hille Barbara Schoepp-Cothenet 《The Journal of biological chemistry》2010,285(27):20442-20451
Here, we describe the characterization of the [2Fe-2S] clusters of arsenite oxidases from Rhizobium sp. NT-26 and Ralstonia sp. 22. Both reduced Rieske proteins feature EPR signals similar to their homologs from Rieske-cyt b complexes, with g values at 2.027, 1.88, and 1.77. Redox titrations in a range of pH values showed that both [2Fe-2S] centers have constant Em values up to pH 8 at ∼+210 mV. Above this pH value, the Em values of both centers are pH-dependent, similar to what is observed for the Rieske-cyt b complexes. The redox properties of these two proteins, together with the low Em value (+160 mV) of the Alcaligenes faecalis arsenite oxidase Rieske (confirmed herein), are in line with the structural determinants observed in the primary sequences, which have previously been deduced from the study of Rieske-cyt b complexes. Since the published Em value of the Chloroflexus aurantiacus Rieske (+100 mV) is in conflict with this sequence analysis, we re-analyzed membrane samples of this organism and obtain a new value (+200 mV). Arsenite oxidase activity was affected by quinols and quinol analogs, which is similar to what is found with the Rieske-cyt b complexes. Together, these results show that the Rieske protein of arsenite oxidase shares numerous properties with its counterpart in the Rieske-cyt b complex. However, two cysteine residues, strictly conserved in the Rieske-cyt b-Rieske and considered to be crucial for its function, are not conserved in the arsenite oxidase counterpart. We discuss the role of these residues. 相似文献
104.
Hauser JE Kadekaro AL Kavanagh RJ Wakamatsu K Terzieva S Schwemberger S Babcock G Rao MB Ito S Abdel-Malek ZA 《Pigment cell research / sponsored by the European Society for Pigment Cell Research and the International Pigment Cell Society》2006,19(4):303-314
Malignant transformation of melanocytes leads to melanoma, the most fatal form of skin cancer. Ultraviolet radiation (UVR)-induced DNA photoproducts play an important role in melanomagenesis. Cutaneous melanin content represents a major photoprotective mechanism against UVR-induced DNA damage, and generally correlates inversely with the risk of skin cancer, including melanoma. Melanoma risk is also determined by susceptibility genes, one of which is the melanocortin 1 receptor (MC1R) gene. Certain MC1R alleles are strongly associated with melanoma. We hereby present experimental evidence for the role of two melanoma risk factors, constitutive pigmentation, as assessed by total melanin, eumelanin and pheomelanin contents, and MC1R genotype and function, in determining the induction and repair of DNA photoproducts in cultured human melanocytes after irradiation with increasing doses of UVR. We found that total melanin and eumelanin contents (MC and EC) correlated inversely with the extent of UVR-induced growth arrest, apoptosis and induction of cyclobutane pyrimidine dimers (CPD), but not with hydrogen peroxide release in melanocytes expressing functional MC1R. In comparison, melanocytes with loss-of-function MC1R, regardless of their MC or EC, sustained more UVR-induced apoptosis and CPD, and exhibited reduced CPD repair. Therefore, MC, mainly EC, and MC1R function are independent determinants of UVR-induced DNA damage in melanocytes. 相似文献
105.
Stefan Krebs Ivica Medugorac Ingolf Russ Pete Ossent Ulrich Bleul Wolfgang Schmahl Martin Förster 《Mammalian genome》2006,17(1):67-76
Bovine spinal muscular atrophy (SMA), an autosomal recessive neurodegenerative disease, has been mapped at moderate resolution
to the distal part of Chromosome 24. In this article we confirm this location and fine-map the SMA locus to an interval of
approximately 0.8 cM at the very distal end of BTA24. Despite remarkable similarity to human SMA, the causative gene SMN can
be excluded in bovine SMA. However, the interval where the disease now has been mapped contains BCL2, like SMN an antiapoptotic
factor, and shown to bind to SMN. Moreover, knockout mice lacking the BCL2 gene show rapid motor neuron degeneration with
early postnatal onset, as observed in bovine SMA. A comparative cattle/human map of the distal end of BTA24, based on the
emerging bovine genome sequencing data, shows conserved synteny to HSA18 with hints of a segmental duplication and pericentic
inversion just after the last available bovine marker DIK4971. This synteny lets us conclude that SMA is in immediate vicinity of the telomere. Candidate gene analysis of BCL2, however,
excludes most of this gene, except its promoter region, and draws attention to the neighboring gene VPS4B, part of the endosomal
protein-sorting machinery ESCRT-III which is involved in several neurodegenerative diseases.
Stefan Krebs and Ivica Medugorac contributed equally to this work and agreed to be considered as first authors. 相似文献
106.
Myosin heavy-chain kinase A (MHCK A) catalyses the disassembly of myosin II filaments in Dictyostelium cells via myosin II heavy-chain phosphorylation. MHCK A possesses a 'coiled-coil'-enriched domain that mediates the oligomerization, cellular localization and actin-binding activities of the kinase. F-actin (filamentous actin) binding by the coiled-coil domain leads to a 40-fold increase in MHCK A activity. In the present study we examined the actin-binding characteristics of the coiled-coil domain as a means of identifying mechanisms by which MHCK A-mediated disassembly of myosin II filaments can be regulated in the cell. Co-sedimentation assays revealed that the coiled-coil domain of MHCK A binds co-operatively to F-actin with an apparent K(D) of approx. 0.5 muM and a stoichiometry of approx. 5:1 [actin/C(1-498)]. Further analyses indicate that the coiled-coil domain binds along the length of the actin filament and possesses at least two actin-binding regions. Quite surprisingly, we found that the coiled-coil domain cross-links actin filaments into bundles, indicating that MHCK A can affect the cytoskeleton in two important ways: (1) by driving myosin II-filament disassembly via myosin II heavy-chain phosphorylation, and (2) by cross-linking/bundling actin filaments. This discovery, along with other supporting data, suggests a model in which MHCK A-mediated bundling of actin filaments plays a central role in the recruitment and activation of the kinase at specific sites in the cell. Ultimately this provides a means for achieving the robust and highly localized disruption of myosin II filaments that facilitates polarized changes in cell shape during processes such as chemotaxis, cytokinesis and multicellular development. 相似文献
107.
Marine reserves demonstrate trophic interactions across habitats 总被引:1,自引:0,他引:1
Several infaunal bivalve taxa show patterns of decreased biomass in areas with higher densities of adjacent reef-associated
predators (the snapper, Pagrus auratus and rock lobster, Jasus edwardsii). A caging experiment was used to test the hypothesis that patterns observed were caused by predation, using plots seeded
with a known initial density of the bivalve Dosinia subrosea to estimate survivorship. The caging experiment was replicated at several sites inside and outside two highly protected marine
reserves: predators are significantly more abundant inside these reserves. Survivorship in fully caged, partially caged and
open plots were then compared at sites having either low (non reserve) or high (reserve) predator density. The highest rates
of survivorship of the bivalve were found in caged plots inside reserves and in all treatments outside reserves. However,
inside reserves, open and partially caged treatments exhibited low survivorship. It was possible to specifically attribute
much of this mortality to predation by large rock lobsters, due to distinctive marks on the valves of dead D. subrosea. This suggests that predation by large rock lobster could indeed account for the distributional patterns previously documented
for certain bivalve populations. Our results illustrate that protection afforded by marine reserves is necessary to investigate
how depletion through fishing pressure can change the role of upper-level predators and trophic processes between habitats.
Electronic Supplementary Material Supplementary material is available for this article at
An erratum to this article can be found at 相似文献
108.
A major challenge for genomewide disease association studies is the high cost of genotyping large number of single nucleotide polymorphisms (SNPs). The correlations between SNPs, however, make it possible to select a parsimonious set of informative SNPs, known as "tagging" SNPs, able to capture most variation in a population. Considerable research interest has recently focused on the development of methods for finding such SNPs. In this paper, we present an efficient method for finding tagging SNPs. The method does not involve computation-intensive search for SNP subsets but discards redundant SNPs using a feature selection algorithm. In contrast to most existing methods, the method presented here does not limit itself to using only correlations between SNPs in local groups. By using correlations that occur across different chromosomal regions, the method can reduce the number of globally redundant SNPs. Experimental results show that the number of tagging SNPs selected by our method is smaller than by using block-based methods. Supplementary website: http://htsnp.stanford.edu/FSFS/. 相似文献
109.
Soluble adenylyl cyclase (sAC) is indispensable for sperm function and fertilization 总被引:1,自引:0,他引:1
Xie F Garcia MA Carlson AE Schuh SM Babcock DF Jaiswal BS Gossen JA Esposito G van Duin M Conti M 《Developmental biology》2006,296(2):353-362
We previously demonstrated that male mice deficient in the soluble adenylyl cyclase (sAC) are sterile and produce spermatozoa with deficits in progressive motility and are unable to fertilize zona-intact eggs. Here, analyses of sAC(-/-) spermatozoa provide additional insights into the functions linked to cAMP signaling. Adenylyl cyclase activity and cAMP content are greatly diminished in crude preparations of sAC(-/-) spermatozoa and are undetectable after sperm purification. HCO(3)(-) is unable to rapidly accelerate the flagellar beat or facilitate evoked Ca(2+) entry into sAC(-/-) spermatozoa. Moreover, the delayed HCO(3)(-)-dependent increases in protein tyrosine phosphorylation and hyperactivated motility, which occur late in capacitation of wild-type spermatozoa, do not develop in sAC(-/-) spermatozoa. However, sAC(-/-) sperm fertilize zona-free oocytes, indicating that gamete fusion does not require sAC. Although ATP levels are significantly reduced in sAC(-/-) sperm, cAMP-AM ester increases flagellar beat frequency, progressive motility, and alters the pattern of tyrosine phosphorylated proteins. These results indicate that sAC and cAMP coordinate cellular energy balance in wild-type sperm and that the ATP generating machinery is not operating normally in sAC(-/-) spermatozoa. These findings demonstrate that sAC plays a critical role in cAMP signaling in spermatozoa and that defective cAMP production prevents engagement of multiple components of capacitation resulting in male infertility. 相似文献
110.
Molybdenum and tungsten in biology 总被引:6,自引:0,他引:6
Hille R 《Trends in biochemical sciences》2002,27(7):360-367
Molybdenum is the only second-row transition metal that is required by most living organisms, and the few species that do not require molybdenum use tungsten, which lies immediately below molybdenum in the periodic table. Because of their unique chemical versatility and unusually high bioavailability these two transition metals have been incorporated into the active sites of enzymes over the course of evolution. Enzymes that contain molybdenum or tungsten continue to be discovered and several crystal structures have become available recently. This new structural information has been complemented by spectroscopic and kinetic methods, as well as computational approaches. Together, these studies provide an increasingly detailed view of the reaction mechanisms and the correlation between the electronic structure of the active site and catalytic function, one of the fundamental goals in metallobiochemistry. 相似文献