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961.
Natalia V Dorogova Elena M Akhmametyeva Sergei A Kopyl Natalia V Gubanova Olga S Yudina Leonid V Omelyanchuk Long-Sheng Chang 《BMC cell biology》2008,9(1):1-15
Background
Drosophila Merlin, the homolog of the human Neurofibromatosis 2 (NF2) gene, is important for the regulation of cell proliferation and receptor endocytosis. Male flies carrying a Mer 3 allele, a missense mutation (Met177→Ile) in the Merlin gene, are viable but sterile; however, the cause of sterility is unknown.Results
Testis examination reveals that hemizygous Mer 3 mutant males have small seminal vesicles that contain only a few immotile sperm. By cytological and electron microscopy analyses of the Mer 3, Mer 4 (Gln170→stop), and control testes at various stages of spermatogenesis, we show that Merlin mutations affect meiotic cytokinesis of spermatocytes, cyst polarization and nuclear shaping during spermatid elongation, and spermatid individualization. We also demonstrate that the lethality and sterility phenotype of the Mer 4 mutant is rescued by the introduction of a wild-type Merlin gene. Immunostaining demonstrates that the Merlin protein is redistributed to the area associated with the microtubules of the central spindle in telophase and its staining is less in the region of the contractile ring during meiotic cytokinesis. At the onion stage, Merlin is concentrated in the Nebenkern of spermatids, and this mitochondrial localization is maintained throughout sperm formation. Also, Merlin exhibits punctate staining in the acrosomal region of mature sperm.Conclusion
Merlin mutations affect spermatogenesis at multiple stages. The Merlin protein is dynamically redistributed during meiosis of spermatocytes and is concentrated in the Nebenkern of spermatids. Our results demonstrated for the first time the mitochondrial localization of Merlin and suggest that Merlin may play a role in mitochondria formation and function during spermatogenesis. 相似文献962.
Westblade LF Minakhin L Kuznedelov K Tackett AJ Chang EJ Mooney RA Vvedenskaya I Wang QJ Fenyö D Rout MP Landick R Chait BT Severinov K Darst SA 《Journal of proteome research》2008,7(3):1244-1250
Bacteriophages are bacterial viruses that infect bacterial cells, and they have developed ingenious mechanisms to modify the bacterial RNA polymerase. Using a rapid, specific, single-step affinity isolation procedure to purify Escherichia coli RNA polymerase from bacteriophage T4-infected cells, we have identified bacteriophage T4-dependent modifications of the host RNA polymerase. We suggest that this methodology is broadly applicable for the identification of bacteriophage-dependent alterations of the host synthesis machinery. 相似文献
963.
964.
Field D Garrity G Gray T Morrison N Selengut J Sterk P Tatusova T Thomson N Allen MJ Angiuoli SV Ashburner M Axelrod N Baldauf S Ballard S Boore J Cochrane G Cole J Dawyndt P De Vos P DePamphilis C Edwards R Faruque N Feldman R Gilbert J Gilna P Glöckner FO Goldstein P Guralnick R Haft D Hancock D Hermjakob H Hertz-Fowler C Hugenholtz P Joint I Kagan L Kane M Kennedy J Kowalchuk G Kottmann R Kolker E Kravitz S Kyrpides N Leebens-Mack J Lewis SE Li K Lister AL Lord P Maltsev N Markowitz V 《Nature biotechnology》2008,26(5):541-547
965.
966.
Karl-Hermann Kock Leonid Pshenichnov Christopher D. Jones Joachim Gröger Rüdiger Riehl 《Polar Biology》2008,31(3):381-393
The most abundant ice fish species observed in catches off the northern tip of the Antarctic Peninsula in the last 25–30 years
has been the spiny ice fish Chaenodraco wilsoni Regan 1914. C. wilsoni has been exploited on a commercial scale from the late 1970s to the end of the 1980s off Joinville–D’Urville Islands (CCAMLR
Statistical Subarea 48.1) and in the Cosmonauts and Cooperation Seas and Prydz Bay in the Indian Ocean sector (CCAMLR Statistical
Division 58.4.2). This paper presents new information on biological features and life history characteristics of C. wilsoni, based on research survey collections along the northern Antarctic Peninsula in 2006 and 2007 and samples taken in the commercial
fishery in 1987. Length frequency compositions from the research surveys demonstrated that fish 21–34 cm long predominated
in the catches. Sexual maturity is attained at 24–25 cm. Absolute fecundity and relative fecundity is low (1,000–2,500 eggs;
6–12 eggs). Oocyte diameter varied from 4.0 to 4.9 mm very close to spawning. Spawning at the tip of the Antarctic Peninsula
is likely to occur in October–November. Remotely operated vehicle deployments in the northern Weddell Sea demonstrated that
C. wilsoni exhibit parental nest guarding where males protect the eggs. The incubation period is likely to be 8 months long. Fish feed
primarily on Antarctic krill (Euphausia superba) in the Antarctic Peninsula region and in the Cosmonauts and Cooperation Seas while fish take ice krill (Euphausia crystallorophias), Pleuragramma antarcticum and myctophids to some extent in other areas. Age determination still awaits validation. Preliminary ageing attempts suggested
a maximum age of about 8–10 years. 相似文献
967.
Structured meaning-signal mappings, i.e., mappings that preserve neighborhood relationships by associating similar signals
with similar meanings, are advantageous in an environment where signals are corrupted by noise and sub-optimal meaning inferences
are rewarded as well. The evolution of these mappings, however, cannot be explained within a traditional language evolutionary
game scenario in which individuals meet randomly because the evolutionary dynamics is trapped in local maxima that do not
reflect the structure of the meaning and signal spaces. Here we use a simple game theoretical model to show analytically that
when individuals adopting the same communication code meet more frequently than individuals using different codes—a result
of the spatial organization of the population—then advantageous linguistic innovations can spread and take over the population.
In addition, we report results of simulations in which an individual can communicate only with its K nearest neighbors and show that the probability that the lineage of a mutant that uses a more efficient communication code
becomes fixed decreases exponentially with increasing K. These findings support the mother tongue hypothesis that human language evolved as a communication system used among kin,
especially between mothers and offspring. 相似文献
968.
Donald JE Hubner IA Rotemberg VM Shakhnovich EI Mirny LA 《Bioinformatics (Oxford, England)》2005,21(10):2539-2540
The conservatism of conservatism (CoC) database presents statistically analyzed information about the conservation of residue positions in folds across protein families. AVAILABILITY: On the web at http://kulibin.mit.edu/coc/ 相似文献
969.
The effect of locomotor activity on respiration rate was studiedin the food-deprived copepod Calanus euxinus tethered to a forcesensor. The power generated by mouth appendages during cruisinglocomotion, with a frequency of 40 Hz, accounted for 0.026 and0.0031 W for metabolic and mechanical processes, respectively.To overcome total hydrodynamic drag during foraging with a meanswimming speed of 3.2 cm s1, the copepods need 0.4 x103 W, equating to 1.3% of total metabolism. The lossesof mechanical energy for body propulsion amounted to 1.3 x 103W, whilst the cost of feeding current generation run up to 1.8x 103 W, or 58% of the total. Changing of locomotor activityand respiration rate during feeding was examined separatelyin tethered and free-swimming copepods. At algal concentrationof 300 µg C L1, the magnitude of specific dynamicaction (SDA) averaged 1.2 ± 0.44 nL O2 µg C1h1 in copepodites V and females, with similar movingactivity before and during feeding. The contribution of SDAinto total metabolism varied from 23 to 85% in C. euxinus withlow activity level and constituted only 10% in active animals.In starved copepods, with low locomotor activity, feeding eventsstimulated the increase in frequency and total duration of locomotionwhich resulted in elevated energy expenditure enhancing theapparent SDA. 相似文献
970.
An analytical approach for the mechanical interaction of the self-expanding Cardiocoil stent with the stenosed artery is presented. The damage factor as the contact stress at the stent-artery interface is determined. The stent is considered as an elastic helical rod having a nonlinear pressure-displacement dependence, while the artery is modeled by an elastic cylindrical shell. An influence of a moderate relative thickness of the shell is estimated. The equations for both the stent and the artery are presented in the stent-associated helical coordinates. The computational efficiency of the model enabled to carry out a parametric study of the damage factor. Comparative examinations are conducted for the stents made of the helical rods with circular and rectangular cross sections. It was found, in particular, that, under same other conditions, the damage factor for the stent with a circular cross section may be two times larger than that for a rectangular one. 相似文献