全文获取类型
收费全文 | 1212篇 |
免费 | 102篇 |
国内免费 | 1篇 |
出版年
2023年 | 4篇 |
2022年 | 13篇 |
2021年 | 28篇 |
2020年 | 22篇 |
2019年 | 29篇 |
2018年 | 21篇 |
2017年 | 38篇 |
2016年 | 39篇 |
2015年 | 67篇 |
2014年 | 63篇 |
2013年 | 86篇 |
2012年 | 107篇 |
2011年 | 109篇 |
2010年 | 65篇 |
2009年 | 57篇 |
2008年 | 62篇 |
2007年 | 87篇 |
2006年 | 82篇 |
2005年 | 67篇 |
2004年 | 55篇 |
2003年 | 49篇 |
2002年 | 52篇 |
2001年 | 12篇 |
2000年 | 12篇 |
1999年 | 5篇 |
1998年 | 12篇 |
1997年 | 7篇 |
1996年 | 5篇 |
1995年 | 12篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1989年 | 1篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1983年 | 1篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1964年 | 2篇 |
1961年 | 1篇 |
1959年 | 1篇 |
1930年 | 1篇 |
1926年 | 1篇 |
排序方式: 共有1315条查询结果,搜索用时 15 毫秒
31.
Parker Camille Zhao Jing Pearce David A. Kovács Attila D. 《Archives of microbiology》2021,203(1):85-96
Archives of Microbiology - Accumulated evidence indicates that the gut microbiota affects brain function and may be altered in neurological diseases. In this study, we analyzed the gut microbiota... 相似文献
32.
ágnes Czikora Ibolya Rutkai Enik? T. Pásztor Andrea Szalai Róbert Pórszász Judit Boczán István édes Zoltán Papp Attila Tóth 《PloS one》2013,8(11)
Background and purpose
TRPV1 is expressed in sensory neurons and vascular smooth muscle cells, contributing to both pain perception and tissue blood distribution. Local desensitization of TRPV1 in sensory neurons by prolonged, high dose stimulation is re-engaged in clinical practice to achieve analgesia, but the effects of such treatments on the vascular TRPV1 are not known.Experimental approach
Newborn rats were injected with capsaicin for five days. Sensory activation was measured by eye wiping tests and plasma extravasation. Isolated, pressurized skeletal muscle arterioles were used to characterize TRPV1 mediated vascular responses, while expression of TRPV1 was detected by immunohistochemistry.Key results
Capsaicin evoked sensory responses, such as eye wiping (3.6±2.5 versus 15.5±1.4 wipes, p<0.01) or plasma extravasation (evans blue accumulation 10±3 versus 33±7 µg/g, p<0.05) were reduced in desensitized rats. In accordance, the number of TRPV1 positive sensory neurons in the dorsal root ganglia was also decreased. However, TRPV1 expression in smooth muscle cells was not affected by the treatment. There were no differences in the diameter (192±27 versus 194±8 µm), endothelium mediated dilations (evoked by acetylcholine), norepinephrine mediated constrictions, myogenic response and in the capsaicin evoked constrictions of arterioles isolated from skeletal muscle.Conclusion and implications
Systemic capsaicin treatment of juvenile rats evokes anatomical and functional disappearance of the TRPV1-expressing neuronal cells but does not affect the TRPV1-expressing cells of the arterioles, implicating different effects of TRPV1 stimulation on the viability of these cell types. 相似文献33.
Tibor Németh Adél Tóth Judit Szenzenstein Péter Horváth Joshua D. Nosanchuk Zsuzsanna Grózer Renáta Tóth Csaba Papp Zsuzsanna Hamari Csaba Vágv?lgyi Attila Gácser 《PloS one》2013,8(7)
The C. parapsilosis sensu lato group involves three closely related species, C. parapsilosis sensu stricto,
C
. orthopsilosis
and
C
. metapsilosis
. Although their overall clinical importance is dramatically increasing, there are few studies regarding the virulence properties of the species of the psilosis complex. In this study, we tested 63 C. parapsilosis sensu stricto, 12
C
. metapsilosis
and 18
C
. orthopsilosis
isolates for the ability to produce extracellular proteases, secrete lipases and form pseudohyphae. Significant differences were noted between species, with the
C
. metapsilosis
strains failing to secrete lipase or to produce pseudohyphae. Nine different clinical isolates each of C. parapsilosis sensu stricto,
C
. orthopsilosis
and
C
. metapsilosis
were co-cultured with immortalized murine or primary human macrophages. C. parapsilosis sensu stricto isolates showed a significantly higher resistance to killing by primary human macrophages compared to
C
. orthopsilosis
and
C
. metapsilosis
isolates. In contrast, the killing of isolates by J774.2 mouse macrophages did not differ significantly between species. However, C. parapsilosis sensu stricto isolates induced the most damage to murine and human macrophages, and
C
. metapsilosis
strains were the least toxic. Furthermore, strains that produced lipase or pseudohyphae were most resistant to macrophage-mediated killing and produced the most cellular damage. Finally, we used 9 isolates of each of the C. parapsilosis sensus lato species to examine their impact on the survival of
Galleria
mellonella
larvae. The mortality rate of
G
. mellonella
larvae infected with
C
. metapsilosis
isolates was significantly lower than those infected with C. parapsilosis sensu stricto or
C
. orthopsilosis
strains. Taken together, our findings demonstrate that
C
. metapsilosis
is indeed the least virulent member of the psilosis group, and also highlight the importance of pseudohyphae and secreted lipases during fungal-host interactions. 相似文献
34.
Natascha Verhagen Attila Teleki Christoph Heinrich Martin Schilling Andreas Unsöld Ralf Takors 《Biotechnology and bioengineering》2020,117(11):3239-3247
The improvement of cell specific productivities for the formation of therapeutic proteins is an important step towards intensified production processes. Among others, the induction of the desired production phenotype via proper media additives is a feasible solution provided that said compounds adequately trigger metabolic and regulatory programs inside the cells. In this study, S-(5′-adenosyl)- l -methionine (SAM) and 5′-deoxy-5′-(methylthio)adenosine (MTA) were found to stimulate cell specific productivities up to approx. 50% while keeping viable cell densities transiently high and partially arresting the cell cycle in an anti-IL-8-producing CHO-DP12 cell line. Noteworthy, MTA turned out to be the chemical degradation product of the methyl group donor SAM and is consumed by the cells. 相似文献
35.
Interaction computing (IC) aims to map the properties of integrable low-dimensional non-linear dynamical systems to the discrete domain of finite-state automata in an attempt to reproduce in software the self-organizing and dynamically stable properties of sub-cellular biochemical systems. As the work reported in this paper is still at the early stages of theory development it focuses on the analysis of a particularly simple chemical oscillator, the Belousov–Zhabotinsky (BZ) reaction. After retracing the rationale for IC developed over the past several years from the physical, biological, mathematical, and computer science points of view, the paper presents an elementary discussion of the Krohn–Rhodes decomposition of finite-state automata, including the holonomy decomposition of a simple automaton, and of its interpretation as an abstract positional number system. The method is then applied to the analysis of the algebraic properties of discrete finite-state automata derived from a simplified Petri net model of the BZ reaction. In the simplest possible and symmetrical case the corresponding automaton is, not surprisingly, found to contain exclusively cyclic groups. In a second, asymmetrical case, the decomposition is much more complex and includes five different simple non-abelian groups whose potential relevance arises from their ability to encode functionally complete algebras. The possible computational relevance of these findings is discussed and possible conclusions are drawn. 相似文献
36.
37.
Weaam Ebrahim Amal H. Aly Attila Mándi Victor Wray El Mokhtar Essassi Tarik Ouchbani Rachid Bouhfid Wenhan Lin Peter Proksch Tibor Kurtán Abdessamad Debbab 《Chirality》2013,25(4):250-256
Three new polyketides (-)-1 , (+)-1 , and 2 ) were isolated from the EtOAc extract of the fungus Embellisia eureka, an endophyte of the Moroccan plant Cladanthus arabicus (Asteraceae). The structures of these new compounds were determined on the basis of one- and two-dimensional NMR spectroscopy as well as by high-resolution mass spectrometry. The absolute configurations of (-)-1 , (+)-1 , and 2 were determined by TDDFT ECD calculations of solution conformers, online HPLC-ECD analysis, and the modified Mosher method. Chirality 25:250–256, 2013. © 2013 Wiley Periodicals, Inc. 相似文献
38.
Attila Borics Richard F. Murphy Sándor Lovas 《Journal of biomolecular structure & dynamics》2013,31(6):761-770
Abstract It was previously shown that the structural ensemble of model peptides DDKG and GKDG (H. Ishii et al. Biopolymers 24, 2045–2056, 1985), DEKS (A. Otter et al. J. Biomol. Struct. Dyn. 7, 455–476, 1989) NPGQ (F. R. Carbone et al. Int. J. Pept. Protein. Res. 26, 498–508, 1985), SALN (H. Santa et al. J. Biomol. Struct. Dyn. 16, 1033–1041, 1999), SYPFDV and SYPYDV (J. Yao et al. J. Mol. Biol. 243, 736–753, 1994), VPDAH and VPDSH (B. Imperiali et al. J. Am. Chem. Soc. 114, 3182–3188, 1992) in solution contains a significant—or in some cases dominant—proportion of β-turn conformation. In this study, a protein database was searched for the above, unprotected sequences which incorporate only L-amino acid residues. Simulated annealing and 25 ns MD simulations of structures were also performed. The DSSP and STRIDE secondary structure-assigning algorithms and clustering were used to analyze trajectories and i, i+3 hydrogen bonds were also sought. The DSSP analysis showed a fluctuation between β-turn and random meander structure, although bend structures were not detected because of the insufficient length of peptide chains. This alternating trend was confirmed when the STRIDE algorithm was used to analyze trajectories, but STRIDE assigned more turn structures. The population of the strongest clusters was above 40% and the middle structures adopted β-turn structure for most sequences. These results are in good agreement with previous experimental results and support the idea of the ultra-marginal stability of turns in the absence of stabilizing long-range interactions of the neighboring segments of a polypeptide chain. However, interactions between the side-chains in tetrapeptides could also contribute to turn stability and result in unusual stability in some cases. Our observations suggest that such interactions are the consequence rather than the driving force of turn formation. 相似文献
39.
Gábor Glatz Gerg? Gógl Anita Alexa Attila Reményi 《The Journal of biological chemistry》2013,288(12):8596-8609
Mitogen-activated protein kinase (MAPK) activation depends on a linear binding motif found in all MAPK kinases (MKK). In addition, the PB1 (Phox and Bem1) domain of MKK5 is required for extracellular signal regulated kinase 5 (ERK5) activation. We present the crystal structure of ERK5 in complex with an MKK5 construct comprised of the PB1 domain and the linear binding motif. We show that ERK5 has distinct protein-protein interaction surfaces compared with ERK2, which is the closest ERK5 paralog. The two MAPKs have characteristically different physiological functions and their distinct protein-protein interaction surface topography enables them to bind different sets of activators and substrates. Structural and biochemical characterization revealed that the MKK5 PB1 domain cooperates with the MAPK binding linear motif to achieve substrate specific binding, and it also enables co-recruitment of the upstream activating enzyme and the downstream substrate into one signaling competent complex. Studies on present day MAPKs and MKKs hint on the way protein kinase networks may evolve. In particular, they suggest how paralogous enzymes with similar catalytic properties could acquire novel signaling roles by merely changing the way they make physical links to other proteins. 相似文献
40.
Chronic coccidian infestation compromises flight feather quality in house sparrows Passer domesticus
Péter L. Pap Csongor I. Vágási Lőrinc Bărbos Attila Marton 《Biological journal of the Linnean Society. Linnean Society of London》2013,108(2):414-428
Parasites usurp indispensable resources for birds during a moult, and this is particularly relevant for those parasites residing in host intestines. This might compromise the nutritionally demanding moult and, thus, feather functionality. Although lower feather quality has profound and multifaceted adverse effects on residual fitness, surprisingly, little is known about parasites' effect on feather traits, especially over the longer term. We conducted an aviary experiment by medicating half of a group of naturally infested house sparrows Passer domesticus against intestinal coccidians for 15 months, spanning two consecutive postnuptial moults, whereas the other half was kept infested (i.e. without medication). Coccidian infestation significantly and negatively affected the size of the uropygial gland during the second moulting period compared to the medicated group. Furthermore, wing length was significantly shorter after the second moulting in the non‐medicated compared to the medicated female birds, which indicates that the negative effects of coccidians emerge only after a prolonged exposure to parasite infestation. Non‐medicated birds grew poorer quality flight feathers detected in a large number of feather traits both after the first and second moults. In the case of non‐medicated birds, the primaries were lighter and shorter, and had a smaller vane area, thinner rachis and decreased stiffness, although a higher barb and barbule density, which may have various consequences for fitness through reducing flight performance. Our findings demonstrate that, besides the well‐known immediate consequences for host breeding success, parasites might also have serious, long‐lasting effects through influencing feather quality and, ultimately, fitness of the host. © 2013 The Linnean Society of London 相似文献