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71.
Tomoya Mita Kosuke Azuma Takashi Nomiyama Takahisa Hirose Ryuzo Kawamori Hirotaka Watada 《Biochemical and biophysical research communications》2010,395(4):477-483
Epidemiological studies suggest that insulin resistance is an independent risk factor for cardiovascular disease. However, there is little information on the role of insulin resistance in atherosclerogenesis independent of LDL cholesterol level. The aim of this study was to investigate the impact of systemic insulin resistance on monocyte adhesion to endothelial cells and atherosclerotic lesions independent of LDL cholesterol level. KKAy mice are obese mice with spontaneous diabetes and insulin resistance, and normal levels of LDL cholesterol. In parallel with systemic insulin resistance, decreased insulin signal, and the increased expression of monocyte chemoattractant protein-1 (MCP-1) were noted in macrophages isolated from KKAy mice. These mice showed enhanced monocyte adhesion to the endothelial cells of the thoracic artery. Furthermore, these mice showed expanded atherosclerotic lesions when fed high cholesterol diet. Our data indicate that insulin resistance promotes the atherosclerogenesis independent of LDL cholesterol level. Decreased insulin signaling in macrophages associated with systemic insulin resistance could be involved, at least in part, in this pathological process. 相似文献
72.
Ferredoxin (Fd) and Fd-NADP(+) reductase (FNR) are redox partners responsible for the conversion between NADP(+) and NADPH in the plastids of photosynthetic organisms. Introduction of specific disulfide bonds between Fd and FNR by engineering cysteines into the two proteins resulted in 13 different Fd-FNR cross-linked complexes displaying a broad range of activity to catalyze the NADPH-dependent cytochrome c reduction. This variability in activity was thought to be mainly due to different levels of intramolecular electron transfer activity between the FNR and Fd domains. Stopped-flow analysis revealed such differences in the rate of electron transfer from the FNR to Fd domains in some of the cross-linked complexes. A group of the cross-linked complexes with high cytochrome c reduction activity comparable to dissociable wild-type Fd/FNR was shown to assume a similar Fd-FNR interaction mode as in the native Fd:FNR complex by analyses of NMR chemical shift perturbation and absorption spectroscopy. However, the intermolecular electron transfer of these cross-linked complexes with two Fd-binding proteins, nitrite reductase and photosystem I, was largely inhibited, most probably due to steric hindrance by the FNR moiety linked near the redox center of the Fd domain. In contrast, another group of the cross-linked complexes with low cytochrome c reduction activity tends to mediate higher intermolecular electron transfer activity. Therefore, reciprocal relationship of intramolecular and intermolecular electron transfer abilities was conferred by the linkage of Fd and FNR, which may explain the physiological significance of the separate forms of Fd and FNR in chloroplasts. 相似文献
73.
Consistent individual differences in correlated behaviours across contexts or situations, that is, behavioural syndromes, have recently been identified as an important factor shaping the evolution of behavioural traits, because of their potential for explaining trade-offs in behavioural responses. We examined a genetic link between abilities to mate and to avoid predation from the viewpoint of two genetically correlated behavioural traits; tonic immobility (TI), which is considered to be an antipredator behaviour, and activity levels in the red flour beetle, Tribolium castaneum. Males derived from two strains artificially selected for divergent durations of TI were used in the present study: the L strain (with longer duration and higher frequency of TI) and the S strain (shorter duration and lower frequency of TI). We found that males of the L strain had higher survival rates in predatory environments than those of the S strain, and lower mating success even in predator-free environments. To our knowledge, this is the first empirical study showing a genetic trade-off between abilities to mate and to avoid predation in relation to behavioural syndromes, using individuals exhibiting different behavioural strategies. 相似文献
74.
Structural organization and a standardized nomenclature for plant endo-1,4-beta-glucanases (cellulases) of glycosyl hydrolase family 9
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75.
Abe T Kakehata S Kitani R Maruya S Navaratnam D Santos-Sacchi J Shinkawa H 《The Journal of membrane biology》2007,215(1):49-56
The development of motor protein activity in the lateral membrane of the mouse outer hair cell (OHC) from postnatal day 5
(P5) to P18 was investigated under whole-cell voltage clamp. Voltage-dependent, nonlinear capacitance (C
v), which represents the conformational fluctuations of the motor molecule, progressively increased during development. At
P12, the onset of hearing in the mouse, C
v was about 70% of the mature level. C
v saturated at P18 when hearing shows full maturation. On the other hand, C
lin, which represents the membrane area of the OHC, showed a relatively small increase with development, reaching steady state
at P10. This early maturation of linear capacitance is further supported by morphological estimates of surface area during
development. These results, in light of recent prestin knockout experiments and our results with quantitative polymerase chain
reaction, suggest that, rather than the incorporation of new motors into the lateral membrane after P10, molecular motors
mature to augment nonlinear capacitance. Thus, current estimates of motor protein density based on charge movement may be
exaggerated. A corresponding indicator of motor maturation, the motor’s operating voltage midpoint, V
pkcm, tended to shift to depolarized potentials during postnatal development, although it was unstable prior to P10. However,
after P14, V
pkcm reached a steady-state level near −67 mV, suggesting that intrinsic membrane tension or intracellular chloride, each of which can modulate V
pkcm, may mature at P14. These developmental data significantly alter our understanding of the cellular mechanisms that control
cochlear amplification and provide a foundation for future analysis of genetic modifications of mouse auditory development. 相似文献
76.
77.
Intra-sexual dimorphism is found in the weapons of many male beetles. Different behavioral tactics to access females between
major and minor males, which adopt fighting and alternative tactics, respectively, are thought to maintain the male dimorphism.
In these species major males have enlarged weapons that they use in fights with rival males. Minor males also have small weapons
in some of these species, and it is unclear why these males possess weapons. We examined the hypothesis that minor males might
adopt a fighting tactic when their status was relatively high in comparison with that of other males (e.g., ownership of a
territory). We observed the behavioral tactics of major and minor males of the beetle Librodor japonicus, whose males have a dimorphism of their mandibles. Major males fought for resources, whereas minor males adopted two status-dependent
tactics, fighting and sneaking, to access females, depending on their ownership of a sap site. We suggest that ownership status-dependent
mating tactics in minor males may maintain the intra-sexual dimorphism in this beetle. 相似文献
78.
Maruyama T Yamamoto Y Kano Y Kurazono M Matsuhisa E Takata H Takata T Atsumi K Iwamatsu K Shitara E 《Bioorganic & medicinal chemistry》2007,15(19):6379-6387
A new series of 1beta-methyl carbapenems possessing a 6,7-disubstituted imidazo[5,1-b]thiazol-2-yl group directly attached to the C-2 position of the carbapenem nucleus was prepared, and the activities of these compounds against methicillin-resistant Staphylococcus aureus (MRSA) were evaluated. To study the effect of basic moieties on anti-MRSA activity, we introduced an amino, or imino, or amidino group at the 6-position of imidazo[5,1-b]thiazole in place of the carbamoylmethyl moiety of CP5068. Anti-MRSA activities of almost all basic group-substituted carbapenems were improved, though some of the compounds showed stronger acute toxicity in mice than IPM. In order to decrease the toxicity without decreasing the activity, we introduced various additional functionalities around the basic moiety. Finally, we obtained CP5484, which has excellent anti-MRSA activity and low acute toxicity. 相似文献
79.
Journal of Ethology - Males of the Japanese scorpionfly, Panorpa japonica, often perform male–male competitions for food to offer to females as a nuptial gift. Previous studies have suggested... 相似文献
80.
Journal of Ethology - Circadian rhythm is an important factor for long-distance movement in insect species. Previous studies have shown the relationship between movement and circadian rhythm,... 相似文献