全文获取类型
收费全文 | 271篇 |
免费 | 7篇 |
专业分类
278篇 |
出版年
2022年 | 5篇 |
2021年 | 8篇 |
2020年 | 4篇 |
2019年 | 4篇 |
2018年 | 9篇 |
2017年 | 9篇 |
2016年 | 7篇 |
2015年 | 12篇 |
2014年 | 12篇 |
2013年 | 10篇 |
2012年 | 24篇 |
2011年 | 21篇 |
2010年 | 9篇 |
2009年 | 12篇 |
2008年 | 23篇 |
2007年 | 18篇 |
2006年 | 15篇 |
2005年 | 12篇 |
2004年 | 9篇 |
2003年 | 14篇 |
2002年 | 11篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1998年 | 5篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有278条查询结果,搜索用时 10 毫秒
231.
Ito Y Tomita T Roy N Nakano A Sugawara-Tomita N Watanabe S Okai N Abe N Kamio Y 《Applied and environmental microbiology》2003,69(12):6969-6978
We have shown that a xylan-degrading bacterium, W-61, excretes multiple xylanases, including xylanase 5 with a molecular mass of 140 kDa. Here, we emend the previously used classification of the bacterium (i.e., Aeromonas caviae W-61) to Paenibacillus sp. strain W-61 on the basis of the nucleotide sequence of the 16S rRNA gene, and we clone and express the xyn5 gene encoding xylanase 5 (Xyn5) in Escherichia coli and study the subcellular localization of Xyn5. xyn5 encodes 1,326 amino acid residues, including a 27-amino-acid signal sequence. Sequence analysis indicated that Xyn5 comprises two family 22 carbohydrate-binding modules (CBM), a family 10 catalytic domain of glycosyl hydrolases, a family 9 CBM, a domain similar to the lysine-rich region of Clostridium thermocellum SdbA, and three S-layer-homologous (SLH) domains. Recombinant Xyn5 bound to a crystalline cellulose, Avicel PH-101, while an N-terminal 90-kDa fragment of Xyn5, which lacks the C-terminal half of the family 9 CBM, did not bind to Avicel PH-101. Xyn5 was cell bound, and the cell-bound protein was digested by exogenous trypsin to produce immunoreactive and xylanolytic fragments with molecular masses of 80 and 60 kDa. Xyn5 was exclusively distributed in the cell envelope fraction consisting of a peptidoglycan-containing layer and an associated S layer. Thus, Paenibacillus sp. strain W-61 Xyn5 is a cell surface-anchored modular xylanase possessing a functional cellulose-binding module and SLH domains. Possible cooperative action of multiple xylanases produced by strain W-61 is discussed on the basis of the modular structure of Xyn5. 相似文献
232.
Abstract: The effect of Zn2+ on t -[3 H]butylbicycloorthobenzoate ([3 H]TBOB) binding to the GABAA receptor complex was studied autoradiographically in rat brain. Zn2+ inhibited [3 H]TBOB binding in a dose-dependent manner at physiological concentrations. Saturation analysis revealed noncompetitive inhibition in various brain regions. The inhibitory effect of Zn2+ had regional heterogeneity; regions showing the greatest inhibition of [3 H]TBOB binding were cortical laminae I–III, most areas of hippocampus, striatum, septum, and cerebellar cortex. Regions with relatively less inhibition of [3 H]TBOB binding included cortical laminae V–VI, thalamus, superior colliculus, inferior colliculus, and central gray matter. The effect of Zn2+ and those of other GABAA ligands, such as benzodiazepines, bicuculline, isoguvacine, and picrotoxin, on [3 H]TBOB binding seemed to be additive. Ni2+ , Cd2+ , and Cu2+ also inhibited [3 H]TBOB binding with a regional heterogeneity similar to that produced by Zn2+ . These results are consistent with Zn2+ acting at the previously detected recognition site on the GABAA receptor complex, distinct from the picrotoxin, GABA, and benzodiazepine sites. The regional heterogeneity of the Zn2+ effect may reflect differential regional distribution of GABAA receptor subtypes among brain regions. Other divalent cations probably act at the Zn2+ binding site. 相似文献
233.
Hosoda C Hiroyama M Sanbe A Birumachi J Kitamura T Cotecchia S Simpson PC Tsujimoto G Tanoue A 《American journal of physiology. Heart and circulatory physiology》2007,293(1):H514-H519
Attenuation of early restenosis after percutaneous coronary intervention (PCI) is important for the successful treatment of coronary artery disease. Some clinical studies have shown that hypertension is a risk factor for early restenosis after PCI. These findings suggest that alpha(1)-adrenergic receptors (alpha(1)-ARs) may facilitate restenosis after PCI because of alpha(1)-AR's remarkable contribution to the onset of hypertension. In this study, we examined the neointimal formation after vascular injury in the femoral artery of alpha(1A)-knockout (alpha(1A)-KO), alpha(1B)-KO, alpha(1D)-KO, alpha(1A)-/alpha(1B)-AR double-KO (alpha(1AB)-KO), and wild-type mice to investigate the functional role of each alpha(1)-AR subtype in neointimal formation, which is known to promote restenosis. Neointimal formation 4 wk after wire injury was significantly (P < 0.05) smaller in alpha(1AB)-KO mice than in any other group of mice, while blood pressures were not altered in any of the groups of mice after wire injury compared with those before it. These results suggest that lack of both alpha(1A)- and alpha(1B)-ARs could be necessary to inhibit neointimal formation in the mouse femoral artery. 相似文献
234.
Faber JE Szymeczek CL Cotecchia S Thomas SA Tanoue A Tsujimoto G Zhang H 《American journal of physiology. Heart and circulatory physiology》2007,292(5):H2316-H2323
Excessive proliferation of vascular wall cells underlies the development of elevated vascular resistance in hypoxic pulmonary hypertension (PH), but the responsible mechanisms remain unclear. Growth-promoting effects of catecholamines may contribute. Hypoxemia causes sympathoexcitation, and prolonged stimulation of alpha(1)-adrenoceptors (alpha(1)-ARs) induces hypertrophy and hyperplasia of arterial smooth muscle cells and adventitial fibroblasts. Catecholamine trophic actions in arteries are enhanced when other conditions favoring growth or remodeling are present, e.g., injury or altered shear stress, in isolated pulmonary arteries from rats with hypoxic PH. The present study examined the hypothesis that catecholamines contribute to pulmonary vascular remodeling in vivo in hypoxic PH. Mice genetically deficient in norepinephrine and epinephrine production [dopamine beta-hydroxylase(-/-) (DBH(-/-))] or alpha(1)-ARs were examined for alterations in PH, cardiac hypertrophy, and vascular remodeling after 21 days exposure to normobaric 0.1 inspired oxygen fraction (Fi(O(2))). A decrease in the lumen area and an increase in the wall thickness of arteries were strongly inhibited in knockout mice (order of extent of inhibition: DBH(-/-) = alpha(1D)-AR(-/-) > alpha(1B)-AR(-/-)). Distal muscularization of small arterioles was also reduced (DBH(-/-) > alpha(1D)-AR(-/-) > alpha(1B)-AR(-/-) mice). Despite these reductions, increases in right ventricular pressure and hypertrophy were not attenuated in DBH(-/-) and alpha(1B)-AR(-/-) mice. However, hematocrit increased more in these mice, possibly as a consequence of impaired cardiovascular activation that occurs during reduction of Fi(O(2)). In contrast, in alpha(1D)-AR(-/-) mice, where hematocrit increased the same as in wild-type mice, right ventricular pressure was reduced. These data suggest that catecholamine stimulation of alpha(1B)- and alpha(1D)-ARs contributes significantly to vascular remodeling in hypoxic PH. 相似文献
235.
The genetic diversity of the Vigna angularis complex in Asia. 总被引:8,自引:0,他引:8
Xu Xiao Zong Akito Kaga Norihiko Tomooka Xin Wang Wang Ouk Kyu Han Duncan Vaughan 《Génome》2003,46(4):647-658
A selected set of accessions of components of the azuki bean (Vigna angularis) complex comprising 123 cultivated accessions and 23 wild or weedy accessions from Bhutan, China (including Taiwan), India, Japan, Korea, and Nepal was analyzed using amplified fragment length polymorphism (AFLP) methodology. Using 12 AFLP primer pairs, 580 unambiguous bands were generated, 313 (53.9%) of which were polymorphic among azuki bean accessions. All 580 bands were used to assess phenotypic (band) and genetic (nucleotide) diversity among the 146 azuki bean accessions. The results indicate five major groups of azuki bean germplasm primarily associated with geographic origin of accessions and their status: wild, weedy, or cultivated. These five groups are (i) Himalayan wild, (ii) Nepal-Bhutan cultivated, (iii) Chinese wild, (iv) Taiwan wild - Bhutan cultivated, and (v) northeast Asian accessions. Within the northeast Asian accessions, three subgroups are present. These consist of (v1) Japanese complex - Korean cultivated, (v2) Japanese cultivated, and (v3) Chinese cultivated accessions. The results suggest domestication of azuki bean occurred at least twice, once in the Himalayan region of southern Asia and once in northeast Asia. The remarkable diversity of azuki bean germplasm in the Himalayan region compared with other regions suggests this is a rich source of germplasm for plant breeding. The results suggest there are important gaps in the germplasm collections of azuki bean and its close relatives from various parts of Asia and that specific collecting missions for Vigna germplasm related to azuki bean in the highlands of subtropical Asia are needed. 相似文献
236.
Pascal Duchatelle Akito Ohara Brian N. Ling Alexandra E. Kemendy Kenneth E. Kokko Paul S. Matsumoto Douglas C. Eaton 《Molecular and cellular biochemistry》1992,114(1-2):27-34
The high selectivity, low conductance, amiloride-blockable, sodium channel of the mammalian distal nephron (i.e. cortical collecting tubule) is the site of discretionary regulation which allows maintainance of total body sodium balance. In order to understand the physiological events that participate in this regulation, we have used the patch-clamp technique which allows us to measure individual Na+ channel currents and permits access to the cytosolic side of the channel-protein as well as its associated regulatory components. Most of our experiments have utilized the A6 amphibian renal cell line, which when grown on permeable supports is an excellent model for the mammalian distal nephron. Different mechanisms have been examined: (1) regulation by hormonal factors such as Anti-Diuretic Hormone (ADH) and aldosterone, (2) regulation by G-proteins, (3) modulation by protein kinase C (PK-C), and (4) modulation by products of arachidonic acid metabolism. Consistent with noise analysis of tight epithelial tissues, ADH treatment increased the number of active channels in apical membrane patches of A6 cells, without any apparent change in the open probability (Po) of the individual channels. Agents that increased intracellular cAMP mimicked the effects of ADH. In contrast, aldosterone was found to act through a dramatic increase in Po rather than through changes in channel density. Inhibition of methylation by deazaadenosine antagonizes the stimulatory effect of aldosterone. In excised inside-out patches GTPS inhibits channel activity, whereas GDPS or pertussis toxin stimulates activity suggesting regulatory control by G-proteins. PK-C has been shown to contribute to feed-back inhibition of apical Na+ conductance in tight epithelia. Raising luminal bath sodium and therefore intracellular Na+ inhibits sodium channel activity, an effect that is prevented by PK-C inhibitors and mimicked by PK-C agonists. Cyclooxygenase metabolites of arachidonic acid have an inhibitory effect on channel activity. Finally, a possible role for tyrosine kinase as well as membrane cytoskeleton in the regulation of sodium channel function is also suggested.Abbreviations ADH
Anti Diuretic Hormone
- AVP
Arginine Vasopressin
- dBcAMP
diButyryl-cyclic Adenosine Mono Phosphate
- NMDG
N-methyl-D-glucamine
- PK-A
Protein Kinase A
- PK-C
Protein kinase C
- GTP
Guanosine 5-Triphosphate
- GDPS
Guanosine 5-O-(2-thiodiphosphate)
- GTPS
Guanosine 5-O-(3-thiotri-phosphate)
- G-protein
Trimeric Guanosine Dependent Protein
- Gi–3
subunit of the Gi–3 type G- protein
- CCT
Cortical Collecting Tubule
- PTX
Pertussis Toxin
- IMCD
Inner Medulary Collecting Duct
- cAMP
Adenosine 3:5-cyclic Monophosphate
- cGMP
Guanosine 3:5-cyclic Monophosphate 相似文献
237.
238.
Keita Fukui Kei Nanatani Yoshihiko Hara Suguru Yamakami Daiki Yahagi Akito Chinen 《Bioscience, biotechnology, and biochemistry》2017,81(9):1837-1844
Under anaerobic conditions, Escherichia coli produces succinate from glucose via the reductive tricarboxylic acid cycle. To date, however, no genes encoding succinate exporters have been established in E. coli. Therefore, we attempted to identify genes encoding succinate exporters by screening an E. coli MG1655 genome library. We identified the yjjPB genes as candidates encoding a succinate transporter, which enhanced succinate production in Pantoea ananatis under aerobic conditions. A complementation assay conducted in Corynebacterium glutamicum strain AJ110655ΔsucE1 demonstrated that both YjjP and YjjB are required for the restoration of succinate production. Furthermore, deletion of yjjPB decreased succinate production in E. coli by 70% under anaerobic conditions. Taken together, these results suggest that YjjPB constitutes a succinate transporter in E. coli and that the products of both genes are required for succinate export. 相似文献
239.
Hideaki Bujo Junichi Nakai Tai Kubo Kazuhiko Fukuda Isamu Akiba Akito Maeda Masayoshi Mishina Shosaku Numa 《FEBS letters》1988,240(1-2)
Muscarinic acetylcholine receptor (mAChR) III expressed in Xenopus oocytes, like mAChR I, mediates activation of a Ca2+-dependent Cl− current, whereas mAChR IV, like mAChR II, principally induces activation of Na+ and K+ currents in a Ca2+-independent manner. mAChR III has a sensitivity to agonist of about one order of magnitude higher than that of mAChR I in mediating the Ca2+-dependent current response in Xenopus oocytes and in stimulating phosphoinositide hydrolysis in NG108-15 neuroblastoma-glioma hybrid cells. The agonist-binding affinity of mAChR III is also about one order of magnitude higher than that of mAChR I. 相似文献
240.
Natural variation in the genes responsible for maturity loci E1, E2, E3 and E4 in soybean 总被引:1,自引:0,他引:1
Yasutaka Tsubokura Satoshi Watanabe Zhengjun Xia Hiroyuki Kanamori Harumi Yamagata Akito Kaga Yuichi Katayose Jun Abe Masao Ishimoto Kyuya Harada 《Annals of botany》2014,113(3):429-441