全文获取类型
收费全文 | 290篇 |
免费 | 26篇 |
国内免费 | 49篇 |
出版年
2024年 | 6篇 |
2023年 | 16篇 |
2022年 | 26篇 |
2021年 | 25篇 |
2020年 | 19篇 |
2019年 | 24篇 |
2018年 | 15篇 |
2017年 | 19篇 |
2016年 | 12篇 |
2015年 | 19篇 |
2014年 | 21篇 |
2013年 | 26篇 |
2012年 | 7篇 |
2011年 | 9篇 |
2010年 | 16篇 |
2009年 | 11篇 |
2008年 | 7篇 |
2007年 | 13篇 |
2006年 | 9篇 |
2005年 | 5篇 |
2004年 | 7篇 |
2003年 | 15篇 |
2002年 | 6篇 |
2001年 | 4篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1996年 | 5篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 5篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1982年 | 1篇 |
排序方式: 共有365条查询结果,搜索用时 109 毫秒
321.
《Cytokine》2013,64(3):237-240
Inflammatory cytokines, such as tumor necrosis factor and the members of the interferon family, are potent mediators of the innate anti-viral immune response. The intracellular anti-viral states resulting from treatment of cultured cells with each of these molecules independently has been well studied; but, within complex tissues, the early inflammatory response is likely mediated by simultaneously expressed mixtures of these, and other, protective anti-viral cytokines. Such cytokine mixtures have been shown to induce potently synergistic anti-viral responses in vitro which are more complex than the simple summation of the individual cytokine response profiles. The physiological role of this ‘cytokine synergy’, however, remains largely unappreciated in vivo. This brief commentary will attempt to summarize the potential effects and mechanisms of anti-viral cytokine synergy as well as present several ‘real-world’ applications where this phenomenon might play an important role. 相似文献
322.
323.
The perception of vowels was studied in chimpanzees and humans, using a reaction time task in which reaction times for discrimination
of vowels were taken as an index of similarity between vowels. Vowels used were five synthetic and natural Japanese vowels
and eight natural French vowels. The chimpanzees required long reaction times for discrimination of synthetic [i] from [u]
and [e] from [o], that is, they need long latencies for discrimination between vowels based on differences in frequency of
the second formant. A similar tendency was observed for discrimination of natural [i] from [u]. The human subject required
long reaction times for discrimination between vowels along the first formant axis. These differences can be explained by
differences in auditory sensitivity between the two species and the motor theory of speech perception. A vowel, which is pronounced
by different speakers, has different acoustic properties. However, humans can perceive these speech sounds as the same vowel.
The phenomenon of perceptual constancy in speech perception was studied in chimpanzees using natural vowels and a synthetic
[o]- [a] continuum. The chimpanzees ignored the difference in the sex of the speakers and showed a capacity for vocal tract
normalization. 相似文献
324.
The aim of this study was to evaluate non-negative matrix factorization (NMF) and concatenated NMF (CNMF) to analyze and reliably extract muscle synergies. NMF and CNMF were used to extract knee joint muscle synergies from surface EMGs collected during a weight bearing, force matching task. Repeatability and between subject similarity were evaluated for each method using intra-class correlation coefficients (ICCs). High repeatability was found for CNMF (>0.99; 0.99–1.0) compared to NMF (>0.26; range 0.26–0.98). Reasonable consistency across subjects was improved using the CNMF over the NMF approach. CNMF was found to be a more reliable approach than NMF and suitable for between subject comparison of muscle synergies. 相似文献
325.
Ming-Bo Qu Shao-Peng Sun Yuan-Sheng Liu Xiao-Rui Deng Jun Yang Qing Yang 《Insect Science》2021,28(3):692-704
The insect group II chitinase (ChtII, also known as Cht10) is a unique chitinase with multiple catalytic and chitin-binding domains. It has been proven genetically to be an essential chitinase for molting. However, ChtII's role in chitin degradation during insect development remains poorly understood. Obtaining this knowledge is the key to fully understanding the chitin degradation system in insects. Here, we investigated the role of OfChtII during the molting of Ostrinia furnacalis, a model lepidopteran pest insect. OfChtII was expressed earlier than OfChtI (OfCht5) and OfChi-h, at both the gene and protein levels during larva–pupa molting as evidenced by quantitative polymerase chain reaction and western blot analyses. A truncated OfChtII, OfChtII-B4C1, was recombinantly expressed in Pichia pastoris cells and purified to homogeneity. The recombinant OfChtII-B4C1 loosened compacted chitin particles and produced holes in the cuticle surface as evidenced by scanning electron microscopy. It synergized with OfChtI and OfChi-h when hydrolyzing insoluble α-chitin. These findings suggested an important role for ChtII during insect molting and also provided a strategy for the coordinated degradation of cuticular chitin during insect molting by ChtII, ChtI and Chi-h. 相似文献
326.
Randolph Blake Jan Brascamp David J. Heeger 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2014,369(1641)
This essay critically examines the extent to which binocular rivalry can provide important clues about the neural correlates of conscious visual perception. Our ideas are presented within the framework of four questions about the use of rivalry for this purpose: (i) what constitutes an adequate comparison condition for gauging rivalry''s impact on awareness, (ii) how can one distinguish abolished awareness from inattention, (iii) when one obtains unequivocal evidence for a causal link between a fluctuating measure of neural activity and fluctuating perceptual states during rivalry, will it generalize to other stimulus conditions and perceptual phenomena and (iv) does such evidence necessarily indicate that this neural activity constitutes a neural correlate of consciousness? While arriving at sceptical answers to these four questions, the essay nonetheless offers some ideas about how a more nuanced utilization of binocular rivalry may still provide fundamental insights about neural dynamics, and glimpses of at least some of the ingredients comprising neural correlates of consciousness, including those involved in perceptual decision-making. 相似文献
327.
Alain Carpentier Jacques Duchateau Karl Hainaut 《Journal of electromyography and kinesiology》1996,6(4):225-233
This work examines the relative contribution of the triceps surae heads and the tibialis anterior (TA) to tension development with reference to voluntary plantarflexion at various velocities and at two articular positions of the knee joint (extended and flexed at 90 °). Subjects were instructed to perform plantarflexion at various submaximal and maximal velocities with no intention of stopping the movement. Voluntary electromyographic (EMG) activity was recorded and the amplitude, duration and integral were analysed. Integrated EMG (IEMG) was normalized with respect to duration. The maximal M wave and the Hoffmann (H) reflex elicited by electrical stimulation of the tibial nerve were recorded in the triceps surae to estimate the effects in gastrocnemii (G) length and motoneuron excitability differences, respectively, in the two knee positions. The results indicate that: (a) although the largest EMG activity was recorded in the extended limb, the greatest maximal velocities were performed in the flexed knee position; (b) with increasing velocity of movement, all triceps surae muscles showed enhanced IEMG activities; (c) at a low velocity of movement the soleus (So1)/G IEMG ratio was larger in the flexed compared to the extended knee; and (d) with increasing velocity, co-activation of agonist and antagonist muscles appeared. It is concluded that the larger maximal velocity of movement observed in the flexed compared to the extended knee was not primarily related to the neural command of the different triceps surae components, but rather to their mechanical properties. Furthermore, co-activation of agonist and antagonist muscles may contribute to the performance of the contractile strategy during rapid movements. 相似文献
328.
329.
《Current biology : CB》2022,32(23):5022-5030.e7
- Download : Download high-res image (114KB)
- Download : Download full-size image
330.
Kim Khuy Khun Gavin J. Ash Mark M. Stevens Ruth K. Huwer Bree A. L. Wilson 《Journal of Applied Entomology》2021,145(6):553-566
This study investigated the interactions between insecticides (acephate and indoxacarb) and fungal entomopathogens (Beauveria bassiana [Bals.-Criv.] Vuill. strain B27, Metarhizium anisopliae [Metschn.] Sorokin strain ECS1, and a commercial B. bassiana product, Velifer® Biological Insecticide) for controlling the macadamia seed weevil, Kuschelorhynchus macadamiae Jennings and Oberprieler, in the laboratory and glasshouse. In the laboratory, additive interactions between insecticides at their full field concentrations (776 mg AI/L of acephate and 75 mg AI/L of indoxacarb) and fungal entomopathogens at 107 conidia/ml (ECS1 and B27) or at full field concentration (0.5 ml of Velifer®/L) were seen at 6 days and 12 days post-application. Under the same experimental conditions, synergistic interactions against K. macadamiae were observed 6 days post-application when fungal entomopathogens at 2.5 × 106 conidia/ml or at 25% of full field concentration (Velifer®) were co-applied with insecticides at 25% of their full field concentrations, whilst additive interactions were again observed at 12 days post-application. In the glasshouse, additive interactions between insecticides (at full field concentrations) and fungal entomopathogens (at 107 conidia/ml, or at full field concentration for Velifer®) were obtained at 6 days and 12 days post-application. The results from this study suggest that acephate and indoxacarb have both synergistic and additive effects against K. macadamiae when deployed together with fungal entomopathogens, depending on the initial concentrations of mixture components. Combined application of entomopathogens with compatible insecticides promises to provide more effective management of K. macadamiae than individual chemical applications. 相似文献