全文获取类型
收费全文 | 1066篇 |
免费 | 56篇 |
国内免费 | 3篇 |
出版年
2024年 | 2篇 |
2023年 | 10篇 |
2022年 | 30篇 |
2021年 | 36篇 |
2020年 | 22篇 |
2019年 | 26篇 |
2018年 | 37篇 |
2017年 | 22篇 |
2016年 | 36篇 |
2015年 | 55篇 |
2014年 | 57篇 |
2013年 | 78篇 |
2012年 | 65篇 |
2011年 | 101篇 |
2010年 | 78篇 |
2009年 | 52篇 |
2008年 | 82篇 |
2007年 | 53篇 |
2006年 | 27篇 |
2005年 | 43篇 |
2004年 | 37篇 |
2003年 | 25篇 |
2002年 | 25篇 |
2001年 | 13篇 |
2000年 | 8篇 |
1999年 | 8篇 |
1998年 | 6篇 |
1997年 | 3篇 |
1996年 | 6篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1974年 | 2篇 |
排序方式: 共有1125条查询结果,搜索用时 31 毫秒
31.
Microscopic methods were used to investigate the morphological characterization of two novel oligotrich ciliates, Spirostrombidium paraurceolare sp. nov. and Spirostrombidium faurefremieti sp. nov., isolated from a mangrove wetland in Zhanjiang and an intertidal sandy beach in Qingdao, respectively. Spirostrombidium paraurceolare sp. nov. is characterized by three thigmotactic and 8–10 buccal membranelles, the girdle kinety spiralling around cell with one and a half whorls, and located at right anterior third of dorsal side anteriorly. Spirostrombidium faurefremieti sp. nov. can be recognized by a prominently deep and broad buccal cavity, two thigmotactic and 15–19 buccal membranelles, and the girdle kinety spiralling around cell with two whorls. The small subunit ribosomal RNA genes of these two species were sequenced and compared with those of their congeners to reveal nucleotide differences. Phylogenetic analyses revealed that the genus Spirostrombidium is non-monophyletic. Spirostrombidium faurefremieti sp. nov. falls into a clade comprising most congeners, but Spirostrombidium paraurceolare sp. nov. branches off and groups with Varistrombidium kielum with moderate support. A key to the identification of Spirostrombidium species is also provided.www.zoobank.org/urn:lsid:zoobank.org:pub:AB96BEE6-BE3A-4B95-B75A-3469B1C53ABB2 相似文献
32.
We investigated the morphology, morphogenesis and small subunit rRNA gene-based phylogeny of three marine urostylids, Uncinata gigantea Bullington, 1940, Holosticha heterofoissneri Hu & Song, 2001, and Holosticha cf. heterofoissneri. The dorsal morphogenesis of Uncinata gigantea shows de novo formation of two groups of anlagen near the marginal rows. Holosticha cf. heterofoissneri demonstrates fragmentation of the first dorsal kinety anlage as in Holosticha heterofoissneri. Our population of H. heterofoissneri corresponds well with previously described populations in terms of its general morphology and ciliary pattern. Uncinata gigantea can be recognized by its large and highly contractile body, yellowish to brownish cell colour, two types of cortical granules, and 20–30 transversely oriented and densely arranged cirri in the left marginal row, which often overlie the buccal vertex. Based on the new data, especially infraciliature, the genus Uncinata is here redefined. Both the morphology and phylogenetic analyses suggest that the genus Uncinata should be classified within the family Urostylidae. In addition, both morphological and morphogenetic data suggest that Holosticha bradburyae Gong et al., 2001 should be transferred to Uncinata as U. bradburyae (Gong et al., 2001) comb. nov., due to its possession of a characteristically prominent beak-like, leftwards curved projection and the developmental mode of the dorsal kineties. This assignment is supported by the phylogenetic analyses, which placed Uncinata gigantea in a clade with U. bradburyae (Gong et al., 2001) comb. nov., and revealed only 1.13% (19 bp) difference in their SSU-rDNA gene sequence. 相似文献
33.
Patrick Mumm Dennis Imes Enrico Martinoia Khaled A.S. AI-Rasheid Dietmar Geiger Irene Marten Rainer Hedrich 《植物生理与分子生物学学报》2013,(5):1550-1563
Anion transporters in plants play a fundamental role in volume regulation and signaling. Currently, two plasma membrane-located anion channel familiesmSLAC/SLAH and ALMTmare known. Among the ALMT family, the root-expressed ALuminium-activated Malate Transporter 1 was identified by comparison of aluminum-tolerant and Al3+-sensitive wheat cultivars and was subsequently shown to mediate voltage-independent malate currents. In con- trast, ALMT12/QUAC1 (QUickly activating Anion Channel1) is expressed in guard cells transporting malate in an Al3+- insensitive and highly voltage-dependent manner. So far, no information is available about the structure and mechanism of voltage-dependent gating with the QUAC1 channel protein. Here, we analyzed gating of QUACl-type currents in the plasma membrane of guard cells and QUACl-expressing oocytes revealing similar voltage dependencies and activation- deactivation kinetics. In the heterologous expression system, QUAC1 was electrophysiologically characterized at increas- ing extra- and intracellular malate concentrations. Thereby, malate additively stimulated the voltage-dependent QUAC1 activity. In search of structural determinants of the gating process, we could not identify transmembrane domains com- mon for voltage-sensitive channels. However, site-directed mutations and deletions at the C-terminus of QUAC1 resulted in altered voltage-dependent channel activity. Interestingly, the replacement of a single glutamate residue, which is con- served in ALMT channels from different clades, by an alanine disrupted QUAC1 activity. Together with C- and N-terminal tagging, these results indicate that the cytosolic C-terminus is involved in the voltage-dependent gating mechanism of QUAC1. 相似文献
34.
Thomas Spallek Martina Beck Sara Ben Khaled Susanne Salomon Gildas Bourdais Swen Schellmann Silke Robatzek 《PLoS genetics》2013,9(12)
The plant immune receptor FLAGELLIN SENSING 2 (FLS2) is present at the plasma membrane and is internalized following activation of its ligand flagellin (flg22). We show that ENDOSOMAL SORTING COMPLEX REQUIRED FOR TRANSPORT (ESCRT)-I subunits play roles in FLS2 endocytosis in Arabidopsis. VPS37-1 co-localizes with FLS2 at endosomes and immunoprecipitates with the receptor upon flg22 elicitation. Vps37-1 mutants are reduced in flg22-induced FLS2 endosomes but not in endosomes labeled by Rab5 GTPases suggesting a defect in FLS2 trafficking rather than formation of endosomes. FLS2 localizes to the lumen of multivesicular bodies, but this is altered in vps37-1 mutants indicating compromised endosomal sorting of FLS2 by ESCRT-I loss-of-function. VPS37-1 and VPS28-2 are critical for immunity against bacterial infection through a role in stomatal closure. Our findings identify that VPS37-1, and likewise VPS28-2, regulate late FLS2 endosomal sorting and reveals that ESCRT-I is critical for flg22-activated stomatal defenses involved in plant immunity. 相似文献
35.
Assaad A. Eid Doug-Yoon Lee Linda J. Roman Khaled Khazim Yves Gorin 《Molecular and cellular biology》2013,33(17):3439-3460
Mesangial matrix accumulation is an early feature of glomerular pathology in diabetes. Oxidative stress plays a critical role in hyperglycemia-induced glomerular injury. Here, we demonstrate that, in glomerular mesangial cells (MCs), endothelial nitric oxide synthase (eNOS) is uncoupled upon exposure to high glucose (HG), with enhanced generation of reactive oxygen species (ROS) and decreased production of nitric oxide. Peroxynitrite mediates the effects of HG on eNOS dysfunction. HG upregulates Nox4 protein, and inhibition of Nox4 abrogates the increase in ROS and peroxynitrite generation, as well as the eNOS uncoupling triggered by HG, demonstrating that Nox4 functions upstream from eNOS. Importantly, this pathway contributes to HG-induced MC fibronectin accumulation. Nox4-mediated eNOS dysfunction was confirmed in glomeruli of a rat model of type 1 diabetes. Sestrin 2-dependent AMP-activated protein kinase (AMPK) activation attenuates HG-induced MC fibronectin synthesis through blockade of Nox4-dependent ROS and peroxynitrite generation, with subsequent eNOS uncoupling. We also find that HG negatively regulates sestrin 2 and AMPK, thereby promoting Nox4-mediated eNOS dysfunction and increased fibronectin. These data identify a protective function for sestrin 2/AMPK and potential targets for intervention to prevent fibrotic injury in diabetes. 相似文献
36.
Majida Charif Amina Bakhchane Omar Abidi Redouane Boulouiz Abdelmajid Eloualid Rachida Roky Hassan Rouba Mostafa Kandil Guy Lenaers Abdelhamid Barakat 《Gene》2013
Mutations in the CLDN14 gene, encoding the tight junction claudin 14 protein has been reported to date in an autosomal recessive form of isolated hearing loss DFNB29. In order to identify the contribution of CLDN14 to inherited deafness in Moroccan population, we performed a genetic analysis of this gene in 80 Moroccan familial cases. Our results show the presence of 7 mutations: 6 being conservative and one leading to a missense mutation (C11T) which was found at heterozygous and homozygous states, with a general frequency of 6.87%. The pathogenicity of the resulting T4M substitution is under discussion. 相似文献
37.
Maxime Gommeaux Mohamed Barakat Gilles Montagnac Richard Christen François Guyot Thierry Heulin 《Geomicrobiology journal》2013,30(1):76-92
Mineralogy and microbiology of sand from Merzouga (Morocco) were simultaneously characterized, with the purpose of contributing to a better understanding of the geomicrobiology of deserts. In spite of very low measured bacterial biomass, bacterial diversity on each of the five defined mineralogical classes, was found high. An original grain by grain cultivation method enabled to obtain bacterial isolates with an unusually high recovery rate. The results of this study show that the genus Arthrobacter is well adapted to this environment with a preference for grains other than the dominant mineral quartz, and that the genera Chelatococcus and Saccharotrix are strongly attached to the grains. 相似文献
38.
Ibtissem Ben Amara Aida Karray Ahmed Hakim Yassine Ben Ali Afef Troudi Nejla Soudani Tahia Boudawara Khaled Mounir Zeghal Najiba Zeghal 《Biological trace element research》2013,156(1-3):230-242
Dimethoate (DM) is an organophosphate insecticide widely used in agriculture and industry and has toxic effects on non-target organisms especially mammalian. However, we still know little about DM-induced kidney injury and its alleviation by natural antioxidants. In the present study, selenium (Se), vitamin E, DM, Se+DM, vitamin E+DM, Se+vitamin E+DM were given to adult rats for 4 weeks. Plasma creatinine and uric acid, kidney MDA, PC, H2O2 and AOPP levels were higher, while Na+-K+-ATPase and LDH values were lower in the DM group than those of controls. A smear without ladder formation on agarose gel was shown in the DM group, indicating random DNA degradation and DM-induced genotoxicity. A decrease in kidney GSH, NPSH and plasma urea levels and an increase in GPx, SOD and catalase activities were observed in the DM group when compared to those of controls. Plasma cystatin C levels increased, indicating a decrease in glomerular filtration rate. When Se or vitamin E was added through diet, the biochemical parameters cited above were partially restored in Se+DM and vitamin E+DM than DM group. The joint effect of Se and vitamin E was more powerful against DM-induced oxidative stress and kidney dysfunction. The changes in biochemical parameters were substantiated by histological data. In conclusion, our results indicated a possible mechanism of DM-induced nephrotoxicity, where renal genotoxicity was noted, membrane-bound ATPases and plasma biomarkers were disturbed. Se and vitamin E ameliorated the toxic effects of this pesticide in renal tissue suggesting their role as potential antioxidants. 相似文献
39.
Raphael Courjaret Satanay Hubrack Arwa Daalis Maya Dib Khaled Machaca 《Journal of cellular physiology》2013,228(12):2386-2398
The TRP gene family encodes primarily cation non‐selective, Ca2+ permeant channels that are involved in a dizzying array of sensory mechanisms. Two channels in this large family TRPV5 and TRPV6 are highly Ca2+ selective and are expressed in epithelia where they are important in Ca2+ uptake. TRPV5/6 are constitutively active, yet the mechanisms regulating their activation in native tissue remains elusive. Here we functionally characterize the Xenopus TRPV6 homolog. xTRPV6 is expressed in the oocyte and encodes a channel that is permeant to divalents including Ca2+, and displays a high permeability to Mg2+. The oocyte does not exhibit functional TRPV6‐like current at rest, showing that the endogenous channel is somehow maintained in an inactive state. We show that endogenous as well as overexpressed xTRPV6 interacts with xTRPC1 and that this interaction inhibits xTRPV6 currents. As such TRPC1 is likely to regulate the activity of TRPV6 under physiological conditions. J. Cell. Physiol. 228: 2386–2398, 2013. © 2013 The Authors. Journal of Cellular Physiology Published by Wiley Periodicals, Inc. 相似文献
40.
A segregating population from the cross between drought sensitive (Variant-2) and drought tolerant (Cham-6) genotypes was made to identify molecular markers linked to wheat (Triticum aestivum L.) flag leaf senescence under water-stress. From 38 random amplified polymorphic DNA (RAPD) primers, 25 inter-simple sequence repeat (ISSR) primers and 46 simple sequence repeat (SRR) primers, tested for polymorphism among parental genotypes and F2 population. Quantitative trait locus (QTL) for flag leaf senescence was associated with 1 RAPD marker (Pr9), 4 ISSR markers (Pr8, AD5, AD2 and AD3), and 1 SSR marker (Xgwm382) and explained 44, 50, 35, 31, 22 and 73 % phenotypic variation, respectively. The genetic distance between flag leaf senescence gene and Pr9 was 10.0 cM (LOD score 22.9). The markers Pr8, AD5, AD2 and AD3 had genetic distances of 10.5, 14.6, 15.6 and 18.1 cM, respectively (LOD scores 22.6, 17.8, 17.5 and 14.6). The genetic distance between Xgwm382 was 3.9 cM (LOD score 33.8). Therefore, the RAPD, ISSR and SSR markers linked to the QTL for the drought-induced flag leaf senescence can be further used in breeding for drought tolerance in wheat. 相似文献