全文获取类型
收费全文 | 2792篇 |
免费 | 166篇 |
国内免费 | 1篇 |
出版年
2022年 | 10篇 |
2021年 | 28篇 |
2020年 | 15篇 |
2019年 | 24篇 |
2018年 | 33篇 |
2017年 | 40篇 |
2016年 | 57篇 |
2015年 | 85篇 |
2014年 | 107篇 |
2013年 | 262篇 |
2012年 | 153篇 |
2011年 | 148篇 |
2010年 | 117篇 |
2009年 | 100篇 |
2008年 | 177篇 |
2007年 | 187篇 |
2006年 | 212篇 |
2005年 | 186篇 |
2004年 | 196篇 |
2003年 | 166篇 |
2002年 | 132篇 |
2001年 | 27篇 |
2000年 | 25篇 |
1999年 | 35篇 |
1998年 | 29篇 |
1997年 | 30篇 |
1996年 | 30篇 |
1995年 | 27篇 |
1994年 | 31篇 |
1993年 | 25篇 |
1992年 | 24篇 |
1991年 | 21篇 |
1990年 | 24篇 |
1989年 | 16篇 |
1988年 | 21篇 |
1987年 | 14篇 |
1986年 | 12篇 |
1985年 | 18篇 |
1984年 | 16篇 |
1983年 | 8篇 |
1982年 | 12篇 |
1981年 | 14篇 |
1980年 | 7篇 |
1979年 | 9篇 |
1978年 | 9篇 |
1977年 | 5篇 |
1976年 | 11篇 |
1975年 | 6篇 |
1974年 | 4篇 |
1973年 | 6篇 |
排序方式: 共有2959条查询结果,搜索用时 31 毫秒
991.
Hidenobu C. Arai Ayako Yukawa Ryu John Iwatate Mako Kamiya Rikiya Watanabe Yasuteru Urano Hiroyuki Noji 《Biophysical journal》2014
Molecular machines fueled by NTP play pivotal roles in a wide range of cellular activities. One common feature among NTP-driven molecular machines is that NTP binding is a major force-generating step among the elementary reaction steps comprising NTP hydrolysis. To understand the mechanism in detail,in this study, we conducted a single-molecule rotation assay of the ATP-driven rotary motor protein F1-ATPase using uridine triphosphate (UTP) and a base-free nucleotide (ribose triphosphate) to investigate the impact of a pyrimidine base or base depletion on kinetics and force generation. Although the binding rates of UTP and ribose triphosphate were 103 and 106 times, respectively, slower than that of ATP, they supported rotation, generating torque comparable to that generated by ATP. Affinity change of F1 to UTP coupled with rotation was determined, and the results again were comparable to those for ATP, suggesting that F1 exerts torque upon the affinity change to UTP via rotation similar to ATP-driven rotation. Thus, the adenine-ring significantly enhances the binding rate, although it is not directly involved in force generation. Taking into account the findings from another study on F1 with mutated phosphate-binding residues, it was proposed that progressive bond formation between the phosphate region and catalytic residues is responsible for the rotation-coupled change in affinity. 相似文献
992.
Relationship between chain collapse and secondary structure formation in a partially folded protein
下载免费PDF全文
![点击此处可从《Biopolymers》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Kanako Nakagawa Yoshiteru Yamada Yoshitaka Matsumura Seiichi Tsukamoto Mio Yamamoto‐Ohtomo Hideaki Ohtomo Takahiro Okabe Kazuo Fujiwara Masamichi Ikeguchi 《Biopolymers》2014,101(6):651-658
Chain collapse and secondary structure formation are frequently observed during the early stages of protein folding. Is the chain collapse brought about by interactions between secondary structure units or is it due to polymer behavior in a poor solvent (coil‐globule transition)? To answer this question, we measured small‐angle X‐ray scattering for a series of β‐lactoglobulin mutants under conditions in which they assume a partially folded state analogous to the folding intermediates. Mutants that were designed to disrupt the secondary structure units showed the gyration radii similar to that of the wild type protein, indicating that chain collapse is due to coil‐globule transitions. © 2013 Wiley Periodicals, Inc. Biopolymers 101: 651–658, 2014. 相似文献
993.
Youhei Saito Akihisa Yukawa Masashi MatozakiHiroki Mikami Tomohiro YamagamiNobuyuki Yamagishi Takahisa Kuga Takumi HatayamaYuji Nakayama 《Experimental cell research》2014
The mammalian stress protein Hsp105α is expressed constitutively and is further induced under stress conditions, whereas the alternative spliced form, Hsp105β is only expressed during mild heat shock. We previously reported that Hsp105α is localized mainly in the cytoplasm, whereas Hsp105β is localized in the nucleus. Consistent with the different localization of these proteins, Hsp105β but not Hsp105α induces the expression of the major stress protein Hsp70. We here identified N-myc and Stat interactor (Nmi), as an Hsp105β-binding protein by yeast two-hybrid screening. Immunoprecipitation and pull-down assay showed that Nmi interacts with Hsp105β in vivo and in vitro. Luciferase reporter gene assay and Western blotting showed that Nmi enhanced both the Hsp105β-induced phosphorylation of Stat3 and the Hsp105β-induced activation of the hsp70 promoter in a manner that is dependent on the Stat3-binding site, which results in an increase in Hsp70 protein levels. Most importantly, mild heat shock-induced Hsp70 expression, which is dependent on Hsp105β, is suppressed by knockdown of endogenous Nmi. These results suggest that Nmi has a role as a positive regulator of Hsp105β-mediated hsp70 gene expression along the Stat3 signaling pathway. 相似文献
994.
Mélanie Carquin Hélène Pollet Maria Veiga-da-Cunha Antoine Cominelli Patrick Van Der Smissen Francisca N’kuli Hervé Emonard Patrick Henriet Hideaki Mizuno Pierre J. Courtoy Donatienne Tyteca 《Journal of lipid research》2014,55(7):1331-1342
We recently reported that trace insertion of exogenous fluorescent (green BODIPY) analogs of sphingomyelin (SM) into living red blood cells (RBCs), partially spread onto coverslips, labels submicrometric domains, visible by confocal microscopy. We here extend this feature to endogenous SM, upon binding of a SM-specific nontoxic (NT) fragment of the earthworm toxin, lysenin, fused to the red monomeric fluorescent protein, mCherry [construct named His-mCherry-NT-lysenin (lysenin*)]. Specificity of lysenin* binding was verified with composition-defined liposomes and by loss of 125I-lysenin* binding to erythrocytes upon SM depletion by SMase. The 125I-lysenin* binding isotherm indicated saturation at 3.5 × 106 molecules/RBC, i.e., ∼3% of SM coverage. Nonsaturating lysenin* concentration also labeled submicrometric domains on the plasma membrane of partially spread erythrocytes, colocalizing with inserted green BODIPY-SM, and abrogated by SMase. Lysenin*-labeled domains were stable in time and space and were regulated by temperature and cholesterol. The abundance, size, positioning, and segregation of lysenin*-labeled domains from other lipids (BODIPY-phosphatidylcholine or -glycosphingolipids) depended on membrane tension. Similar lysenin*-labeled domains were evidenced in RBCs gently suspended in 3D-gel. Taken together, these data demonstrate submicrometric compartmentation of endogenous SM at the membrane of a living cell in vitro, and suggest it may be a genuine feature of erythrocytes in vivo. 相似文献
995.
Aims
We previously reported that fluvoxamine, a selective serotonin reuptake inhibitor with high affinity for the σ1-receptor (σ1R), ameliorates cardiac hypertrophy and dysfunction via σ1R stimulation. Although σ1R on non-cardiomyocytes interacts with the IP3 receptor (IP3R) to promote mitochondrial Ca2 + transport, little is known about its physiological and pathological relevance in cardiomyocytes.Main methods
Here we performed Ca2 + imaging and measured ATP production to define the role of σ1Rs in regulating sarcoplasmic reticulum (SR)-mitochondrial Ca2 + transport in neonatal rat ventricular cardiomyocytes treated with angiotensin II to promote hypertrophy.Key finding
These cardiomyocytes exhibited imbalances in expression levels of σ1R and IP3R and impairments in both phenylephrine-induced mitochondrial Ca2 + mobilization from the SR and ATP production. Interestingly, σ1R stimulation with fluvoxamine rescued impaired mitochondrial Ca2 + mobilization and ATP production, an effect abolished by treatment of cells with the σ1R antagonist, NE-100. Under physiological conditions, fluvoxamine stimulation of σ1Rs suppressed intracellular Ca2 + mobilization through IP3Rs and ryanodine receptors (RyRs). In vivo, chronic administration of fluvoxamine to TAC mice also rescued impaired ATP production.Significance
These results suggest that σ1R stimulation with fluvoxamine promotes SR-mitochondrial Ca2 + transport and mitochondrial ATP production, whereas σ1R stimulation suppresses intracellular Ca2 + overload through IP3Rs and RyRs. These mechanisms likely underlie in part the anti-hypertrophic and cardioprotective action of the σ1R agonists including fluvoxamine. 相似文献996.
Hideaki Ando Katsuhiro KawaaiKatsuhiko Mikoshiba 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》2014
IRBIT (also called AHCYL1) was originally identified as a binding protein of the intracellular Ca2 + channel inositol 1,4,5-trisphosphate (IP3) receptor and functions as an inhibitory regulator of this receptor. Unexpectedly, many functions have subsequently been identified for IRBIT including the activation of multiple ion channels and ion transporters, such as the Na+/HCO3− co-transporter NBCe1-B, the Na+/H+ exchanger NHE3, the Cl− channel cystic fibrosis transmembrane conductance regulator (CFTR), and the Cl−/HCO3− exchanger Slc26a6. The characteristic serine-rich region in IRBIT plays a critical role in the functions of this protein. In this review, we describe the evolution, domain structure, expression pattern, and physiological roles of IRBIT and discuss the potential molecular mechanisms underlying the coordinated regulation of these diverse ion channels/transporters through IRBIT. This article is part of a Special Issue entitled: Calcium signaling in health and disease. Guest Editors: Geert Bultynck, Jacques Haiech, Claus W. Heizmann, Joachim Krebs, and Marc Moreau. 相似文献
997.
Chengwei Liu Motoyoshi Noike Atsushi Minami Hideaki Oikawa Tohru Dairi 《Applied microbiology and biotechnology》2014,98(1):199-206
Paxilline is an indole-diterpene produced by Penicillium paxilli. Six genes (paxB, C, G, M, P, and Q) in paxilline biosynthetic gene cluster were previously shown to be responsible for paxilline biosynthesis. In this study, we have characterized paxD, which is located next to paxQ and has weak similarities to fungal dimethylallyl tryptophan synthase genes. PaxD was overexpressed in Escherichia coli and the purified enzyme was used for in vitro analysis. When paxilline and dimethylallyl diphosphate were used as substrates, one major and one minor product, which were identified as di-prenyl paxilline and mono-prenyl paxilline by liquid chromatography–mass spectrometry analysis, were formed. The structure of the major product was determined to be 21,22-diprenylated paxilline, showing that PaxD catalyzed the successive di-prenylation. Traces of both products were detected in culture broth of P. paxilli by liquid chromatography–mass spectrometry analysis. The enzyme is likely to be a dimer and required no divalent cations. The optimum pH and temperature were 8.0 and 37 °C, respectively. The Km values were calculated as 106.4?±?5.4 μM for paxilline and 0.57?±?0.02 μM for DMAPP with a kcat of 0.97?±?0.01/s. 相似文献
998.
Akemi Nakano Kenta Masuda Taisuke Hiromoto Katsunori Takahashi Yoshitake Matsumoto Ahmed G. K. Habib Ahmed G. G. Darwish Masashi Yukawa Eiko Tsuchiya Masaru Ueno 《Molecular and cellular biology》2014,34(8):1389-1397
The spindle assembly checkpoint (SAC) monitors defects in kinetochore-microtubule attachment or lack of tension at kinetochores and arrests cells at prometaphase. In fission yeast, the double mutant between pot1Δ and the helicase-dead point mutant of the RecQ helicase Rqh1 gene (rqh1-hd) accumulates Rad51-dependent recombination intermediates at telomeres and enters mitosis with those intermediates. Here, we found that SAC-dependent prometaphase arrest occurred more frequently in pot1Δ rqh1-hd double mutants than in rqh1-hd single mutants. SAC-dependent prometaphase arrest also occurred more frequently in rqh1-hd single mutants after cells were released from DNA replication block compared to the rqh1-hd single mutant in the absence of exogenous insult to the DNA. In both cases, Mad2 foci persisted longer than usual at kinetochores, suggesting a defect in kinetochore-microtubule attachment. In pot1Δ rqh1-hd double mutants and rqh1-hd single mutants released from DNA replication block, SAC-dependent prometaphase arrest was suppressed by the removal of the recombination or replication intermediates. Our results indicate that the accumulation of recombination or replication intermediates induces SAC-dependent prometaphase arrest, possibly by affecting kinetochore-microtubule attachment. 相似文献
999.
Hideaki Nagano Akihito Fukudome Akihiro Hiraguri Hiromitsu Moriyama Toshiyuki Fukuhara 《Nucleic acids research》2014,42(3):1845-1856
In Arabidopsis thaliana, Dicer-like 3 (DCL3) and Dicer-like 4 (DCL4) cleave long, perfect double-stranded RNAs (dsRNAs) into 24 and 21 nucleotides (nt) small interfering RNAs, respectively, which in turn function in RNA-directed DNA methylation and RNA interference, respectively. To reveal how DCL3 and DCL4 individually recognize long perfect dsRNAs as substrates, we biochemically characterized DCL3 and DCL4 and compared their enzymatic properties. DCL3 preferentially cleaves short dsRNAs with 5′ phosphorylated adenosine or uridine and a 1 nt 3′ overhang, whereas DCL4 cleaves long dsRNAs with blunt ends or with a 1 or 2 nt 3′ overhang with similar efficiency. DCL3 produces 24 nt RNA duplexes with 2 nt 3′ overhangs by the 5′ counting rule. Inorganic phosphate, NaCl and KCl enhance DCL3 activity but inhibit DCL4 activity. These results indicate that plants use DCLs with distinct catalytic profiles to ensure each dsRNA substrate generates only a specific length of siRNAs that trigger a unique siRNA-mediated response. 相似文献
1000.
Hiroshi Kawai Akira Kitamura Mari Mimura Tetsuro Mimura Tomoya Tahara Daiki Aida Kenji Sato Hideaki Sasaki 《Journal of plant research》2014,127(1):23-42
Accumulations of radionuclides in marine macroalgae (seaweeds) resulting from the Fukushima 1 Nuclear Power Plant (F1NPP) accident in March 2011 have been monitored for two years using high-purity germanium detectors. Algal specimens were collected seasonally by snorkeling at Nagasaki, Iwaki, Fukushima Prefecture (Pref.), Japan, ca. 50 km perimeter from the F1NPP. Additional collections were done at Soma, Hironocho, Hisanohama and Shioyazaki in Fukushima Pref. as well as at Chiba Pref. and Hyogo Pref. as controls. In May 2011, specimens of most macroalgal species showed 137Cs levels greater than 3,000 Bq kg?1 at Shioyazaki and Nagasaki. The highest 137Cs level recorded 7371.20 ± 173.95 Bq kg?1 in Undaria pinnatifida (Harvey) Suringar on 2 May 2011, whereas seawater collected at the same time at Shioyazaki and Nagasaki measured 8.41 ± 3.21 and 9.74 ± 3.43 Bq L?1, respectively. The concentration factor of marine macroalgae was estimated to be ca. 8–50, depending on taxa and considering a weight ratio of wet/dry samples of ca. 10. 137Cs level declined remarkably during the following 5–6 months. In contrast, the 137Cs level remained rather stable during the following 12–16 months, and maintained the range of 10–110 Bq kg?1. Contamination was still detectable in many samples in March 2013, 24 months after the most significant pollution. 相似文献