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61.
Alexander Rebl Bernd Köllner Eckhard Anders Klaus Wimmers Tom Goldammer 《Molecular biology reports》2010,37(5):2333-2339
Peptidylarginine deiminase (PADI)-like cDNA sequence was isolated from rainbow trout (Oncorhynchus mykiss). It consists of a 111-bp 5′-untranslated region, a 731-bp 3′-UTR, and a 2,010-bp open reading frame encoding a protein of
669 amino acids. In the presence of calcium ions, PADI enzymes catalyze the post-translational modification reaction generating
citrulline residues. Mammalian PADI enzymes are involved in a number of regulatory processes during cell differentiation and
development such as skin keratinization, myelin maturation, and histone deimination. Though five PADI isotypes have been isolated
from mammals, in bony fish only one PADI enzyme is present, which contains conserved amino acid residues responsible for catalysis
and calcium ion-binding. Sequence identity of piscine PADI protein sequences available at gene databases exceeds 67%. Phylogenetic
analyses revealed that not only piscine, but also amphibian and avian PADI-like proteins share most identical amino acid residues
with mammalian PADI2. mRNA level of trout PADI-like gene is high in skin, fin, gills, brain, and spleen of rainbow trout.
Quantitative Real-Time RT-PCR revealed that PADI gene is differentially expressed in liver, trunk kidney, and spleen of two
trout strains, the freshwater-cultured STEELHEAD trout and the brackish water strain BORN. 相似文献
62.
In the literature, particularly in primatological books, the Peruvian red uakari (Cacajao calvus ucayalii) is generally considered as a species that is specialized on living in flooded forest, despite existing evidence to the contrary.
Here we review all available information on habitats where Cacajao calvus ucayalii have been observed. Most sightings are from terra firme, including palm swamps, or from mixed habitats, including terra firme
and flooded forest. Therefore, we conclude that the species is not a flooded-forest specialist, but is flexible in its habitat
requirements and generally uses terra firme forests or a mixture of habitats. Proper recognition of habitat requirements is
important for understanding the ecoethological adaptations of a species and for appropriate conservation measures. 相似文献
63.
Collective vigilance is considered a major advantage of group living in animals. We investigated vigilance behavior in wild
mustached tamarins (Saguinus mystax), small, arboreal, cooperatively breeding New World primates that form stable mixed-species groups with saddleback tamarins
(Saguinus fuscicollis). We aimed 1) to investigate whether vigilance patterns change according to individual activity and 2) to examine whether
there is a social component of vigilance in their cooperative and nonaggressive society. We studied 11 factors that may influence
vigilance and used this data to interpret the possible functions of vigilance. We observed 44 individuals in 3 mixed-species
and 2 single-species groups of 2 populations that differed in population density and home range sizes. Vigilance changed greatly
when individuals were engaged in different activities and individual vigilance was affected by different sets of factors depending
on the activity. As vigilance decreased in proximity of conspecifics and heterospecifics when feeding, and in larger mixed-species
groups when resting, we conclude that the predominant function of vigilance in mustached tamarins is predator related. However,
the absence of the group size effect in very large single-species groups suggests that it may also function to maintain group
cohesion. In the population with higher density and smaller home ranges individuals also increased their vigilance in home
range overlap areas. We found no evidence that mustached tamarins monitor group mates to avoid food stealing or aggression.
The effect of heterospecifics on individual vigilance suggests that collective vigilance might have been an important incentive
in the evolution of tamarin mixed-species groups. 相似文献
64.
Laurence Culot Fernando Julio João Muñoz Lazo Marie-Claude Huynen Pascal Poncin Eckhard W. Heymann 《International journal of primatology》2010,31(4):553-569
Reduced dispersal of large seeds into degraded areas is one of the major factors limiting rain forest regeneration, as many
seed dispersers capable of transporting large seeds avoid these sites with a limited forest cover. However, the small size
of tamarins allows them to use small trees, and hence to disperse seeds into young secondary forests. Seasonal variations
in diet and home range use might modify their contribution to forest regeneration through an impact on the seed rain. For
a 2-yr period, we followed a mixed-species group of tamarins in Peru to determine how their role as seed dispersers in a 9-yr-old
secondary-growth forest varied across seasons. These tamarins dispersed small to large seeds of 166 tree species, 63 of which
were into a degraded area. Tamarins’ efficiency in dispersing seeds from primary to secondary forest varied across seasons.
During the late wet season, high dietary diversity and long forays in secondary forest allowed them to disperse large seeds
involved in later stages of regeneration. This occurred precisely when tamarins spent a more equal amount of time eating a
high diversity of fruit species in primary forest and pioneer species in secondary forest. We hypothesized that well-balanced
fruit availability induced the movement of seed dispersers between these 2 habitats. The noteworthy number of large-seeded
plant species dispersed by such small primates suggests that tamarins play an important, but previously neglected, role in
the regeneration and maintenance of forest structure. 相似文献
65.
RNAs in biological processes often interconvert between defined structures. These RNA structure conversions are assisted by proteins and are frequently coupled to ATP hydrolysis. It is not well understood how proteins coordinate RNA structure conversions and which role ATP hydrolysis has in these processes. Here, we have investigated in vitro how the DEAD-box ATPase Ded1 facilitates RNA structure conversions in a simple model system. We find that Ded1 assists RNA structure conversions via two distinct pathways. One pathway requires ATP hydrolysis and involves the complete disassembly of the RNA strands. This pathway represents a kinetically controlled steady state between the RNA structures, which allows formation of less stable from more stable RNA conformations and thus RNA structure conversion against thermodynamic equilibrium values. The other pathway is ATP-independent and proceeds via multipartite intermediates that are stabilized by Ded1. Our results provide a basic mechanistic framework for protein-assisted RNA structure conversions that illuminates the role of ATP hydrolysis and reveal an unexpected diversity of pathways. 相似文献
66.
Halls C Mohr S Del Campo M Yang Q Jankowsky E Lambowitz AM 《Journal of molecular biology》2007,365(3):835-855
The RNA-catalyzed splicing of group I and group II introns is facilitated by proteins that stabilize the active RNA structure or act as RNA chaperones to disrupt stable inactive structures that are kinetic traps in RNA folding. In Neurospora crassa and Saccharomyces cerevisiae, the latter function is fulfilled by specific DEAD-box proteins, denoted CYT-19 and Mss116p, respectively. Previous studies showed that purified CYT-19 stimulates the in vitro splicing of structurally diverse group I and group II introns, and uses the energy of ATP binding or hydrolysis to resolve kinetic traps. Here, we purified Mss116p and show that it has RNA-dependent ATPase activity, unwinds RNA duplexes in a non-polar fashion, and promotes ATP-independent strand-annealing. Further, we show that Mss116p binds RNA non-specifically and promotes in vitro splicing of both group I and group II intron RNAs, as well as RNA cleavage by the aI5gamma-derived D135 ribozyme. However, Mss116p also has ATP hydrolysis-independent effects on some of these reactions, which are not shared by CYT-19 and may reflect differences in its RNA-binding properties. We also show that a non-mitochondrial DEAD-box protein, yeast Ded1p, can function almost as efficiently as CYT-19 and Mss116p in splicing the yeast aI5gamma group II intron and less efficiently in splicing the bI1 group II intron. Together, our results show that Mss116p, like CYT-19, can act broadly as an RNA chaperone to stimulate the splicing of diverse group I and group II introns, and that Ded1p also has an RNA chaperone activity that can be assayed by its effect on splicing mitochondrial introns. Nevertheless, these DEAD-box protein RNA chaperones are not completely interchangeable and appear to function in somewhat different ways, using biochemical activities that have likely been tuned by coevolution to function optimally on specific RNA substrates. 相似文献
67.
Pickhardt M Larbig G Khlistunova I Coksezen A Meyer B Mandelkow EM Schmidt B Mandelkow E 《Biochemistry》2007,46(35):10016-10023
One of the key pathological features of Alzheimer's disease is the aggregation of tau protein. We are therefore searching for compounds capable of inhibiting this reaction. On the basis of an initial screen of 200000 compounds [Pickhardt, M., Gazova, Z., von Bergen, M., Khlistunova, I., Wang, Y., Hascher, A., Mandelkow, E. M., Biernat, J., and Mandelkow, E. (2005) Anthraquinones inhibit tau aggregation and dissolve Alzheimer's paired helical filaments in vitro and in cells, J. Biol. Chem. 280, 3628-3635], we performed an in silico screen and predicted a new phenylthiazolyl-hydrazide (PTH) compound as a possible hit [Larbig, G., Pickhardt, M., Lloyd, D. G., Schmidt, B., and Mandelkow, E. (2007) Screening for inhibitors of tau protein aggregation into Alzheimer paired helical filaments: A ligand based approach results in successful scaffold hopping. Curr. Alzheimer Res. 4 (3), 315-323.]. Synthesis of this compound showed that it was indeed active in terms of inhibiting de novo tau aggregation and disassembling preformed aggregates (IC50 = 7.7 microM and DC50 = 10.8 microM). We have now synthesized 49 similar structures and identified the core of the PTHs to be crucial for activity, thus representing a lead structure. Analysis of the binding epitope by saturation transfer difference NMR shows strong interactions between the tau protein and the ligand in the aromatic regions of the inhibitor. By chemical variation of the core, we improved the inhibitory potency five-fold. The compounds showed a low toxicity as judged by an N2A cell model of tau aggregation and lend themselves for further development. 相似文献
68.
RNA helicases--one fold for many functions 总被引:4,自引:0,他引:4
RNA helicases are a large group of enzymes that function in virtually all aspects of RNA metabolism. Although RNA helicases share a highly conserved structure, different enzymes display a wide array of biochemical activities, including RNA duplex unwinding, protein displacement from RNA and strand annealing. Recent structural and functional studies have started to illuminate the mechanisms by which this remarkable diversity of functions can be conducted by the conserved helicase fold. 相似文献
69.
Journal of Applied Phycology - Marine macroalgae such as Ulva intestinalis have promising properties as feedstock for cosmetics and pharmaceuticals. However, since the quantity and quality of... 相似文献
70.