全文获取类型
收费全文 | 668篇 |
免费 | 37篇 |
出版年
2022年 | 8篇 |
2021年 | 20篇 |
2020年 | 8篇 |
2019年 | 8篇 |
2018年 | 15篇 |
2017年 | 10篇 |
2016年 | 17篇 |
2015年 | 37篇 |
2014年 | 35篇 |
2013年 | 69篇 |
2012年 | 45篇 |
2011年 | 39篇 |
2010年 | 29篇 |
2009年 | 28篇 |
2008年 | 49篇 |
2007年 | 39篇 |
2006年 | 33篇 |
2005年 | 40篇 |
2004年 | 36篇 |
2003年 | 25篇 |
2002年 | 24篇 |
2001年 | 11篇 |
2000年 | 9篇 |
1999年 | 8篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 1篇 |
1988年 | 5篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1971年 | 1篇 |
1968年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有705条查询结果,搜索用时 187 毫秒
91.
Akane Meguro Keiko Fujita Hitoshi Kunoh Timothy L. W. Carver Ralph L. Nicholson 《Mycoscience》2001,42(2):201-209
The release of extracellular matrix (ECM) and the emergence of germ tubes from conidia ofBlumeria graminis were studied by light microscopy and micromanipulation. More prompt and frequent ECM release was confirmed on an artificial
hydrophobic substratum than on an artificial hydrophilic substratum. Conidia initially incubated on the hydrophilic substratum
were transferred by micromanipulation to either the hydrophobic or the hydrophilic substrata. Immediately after transfer onto
the hydrophobic substratum, 75% of conidia released ECM, whereas only 16% did so upon transfer to the hydrophilic substratum.
Conidia transferred onto the hydrophobic substratum produced a primary germ tube (PGT) more promptly and frequently than those
transferred to the hydrophilic substratum. Thus, conidia recognize and respond to substratum hydrophobicity perhaps immediately
after contact. When inoculated onto either isolated barley cuticle or the hydrophobic artificial substratum, 2/3 of the conidia
produced a PGT from their polar regions. By contrast, on the hydrophilic substratum 2/3 of conidia did so from the side region.
These results show that substratum hydrophobicity affects the location of PGT emergence from conidia. Furthermore, the study
indicates that very rapid recognition of surface hydrophobicity by conidia promotes ECM release and this in turn may influence
the location of PGT emergence. 相似文献
92.
Kazuhiro Ishibashi Natsuki Mawatari Shuhei Miyashita Hirohisa Kishino Tetsuo Meshi Masayuki Ishikawa 《PLoS pathogens》2012,8(10)
During antagonistic coevolution between viruses and their hosts, viruses have a major advantage by evolving more rapidly. Nevertheless, viruses and their hosts coexist and have coevolved, although the processes remain largely unknown. We previously identified Tm-1 that confers resistance to Tomato mosaic virus (ToMV), and revealed that it encodes a protein that binds ToMV replication proteins and inhibits RNA replication. Tm-1 was introgressed from a wild tomato species Solanum habrochaites into the cultivated tomato species Solanum lycopersicum. In this study, we analyzed Tm-1 alleles in S. habrochaites. Although most part of this gene was under purifying selection, a cluster of nonsynonymous substitutions in a small region important for inhibitory activity was identified, suggesting that the region is under positive selection. We then examined the resistance of S. habrochaites plants to ToMV. Approximately 60% of 149 individuals from 24 accessions were resistant to ToMV, while the others accumulated detectable levels of coat protein after inoculation. Unexpectedly, many S. habrochaites plants were observed in which even multiplication of the Tm-1-resistance-breaking ToMV mutant LT1 was inhibited. An amino acid change in the positively selected region of the Tm-1 protein was responsible for the inhibition of LT1 multiplication. This amino acid change allowed Tm-1 to bind LT1 replication proteins without losing the ability to bind replication proteins of wild-type ToMV. The antiviral spectra and biochemical properties suggest that Tm-1 has evolved by changing the strengths of its inhibitory activity rather than diversifying the recognition spectra. In the LT1-resistant S. habrochaites plants inoculated with LT1, mutant viruses emerged whose multiplication was not inhibited by the Tm-1 allele that confers resistance to LT1. However, the resistance-breaking mutants were less competitive than the parental strains in the absence of Tm-1. Based on these results, we discuss possible coevolutionary processes of ToMV and Tm-1. 相似文献
93.
A Catechin‐rich Beverage Improves Obesity and Blood Glucose Control in Patients With Type 2 Diabetes
Tomonori Nagao Shinichi Meguro Tadashi Hase Kazuhiro Otsuka Masanori Komikado Ichiro Tokimitsu Takashi Yamamoto Kunio Yamamoto 《Obesity (Silver Spring, Md.)》2009,17(2):310-317
We investigated the effects of continuous ingestion of a catechin‐rich beverage in patients with type 2 diabetes who were not receiving insulin (Ins) therapy in a double‐blind controlled study. The participants ingested green tea containing either 582.8 mg of catechins (catechin group; n = 23) or 96.3 mg of catechins (control group; n = 20) per day for 12 weeks. At week 12, the decrease in waist circumference was significantly greater in the catechin group than in the control group. Adiponectin, which is negatively correlated with visceral adiposity, increased significantly only in the catechin group. Although the increase in Ins at week 12 was significantly greater in the catechin group than in the control group, no apparent difference was noted between the two groups in glucose and hemoglobin A1c. In patients treated with insulinotropic agents, the increase in Ins at week 12 was significantly greater in the catechin group than in the control group. This significant increase in Ins levels was observed only in the catechin group. In the catechin group receiving other treatments, Ins levels remained unchanged. In addition, in patients treated with insulinotropic agents, the decrease in hemoglobin A1c at week 12 was significantly greater in the catechin group than in the control group. These results suggest that a catechin‐rich beverage might have several therapeutic uses: in the prevention of obesity; in the recovery of Ins‐secretory ability; and, as a way to maintain low hemoglobin A1c levels in type 2 diabetic patients who do not yet require Ins therapy. 相似文献
94.
Sulfate-reducing microbes utilize sulfate as an electron acceptor and produce sulfide that is depleted in heavy isotopes of sulfur relative to sulfate. Thus, the distribution of sulfur isotopes in sediments can trace microbial sulfate reduction (MSR), and it also has the potential to reflect the physiology of sulfate-reducing microbes. This study investigates the relationship between the availability of iron and reduced nitrogen and the magnitude of S-isotope fractionation during MSR by a marine sulfate-reducing bacterium, DMSS-1, a Desulfovibrio species, isolated from salt marsh in Cape Cod, MA. Submicromolar levels of iron increase sulfur isotope fractionation by about 50% relative to iron-replete cultures of DMSS-1. Iron-limited cultures also exhibit decreased cytochrome c-to-total protein ratios and cell-specific sulfate reduction rates (csSRR), implying changes in the electron transport chain that couples carbon and sulfur metabolisms. When DMSS-1 fixes nitrogen in ammonium-deficient medium, it also produces larger fractionation, but it occurs at faster csSRRs than in the ammonium-replete control cultures. The energy and reducing power required for nitrogen fixation may be responsible for the reverse trend between S-isotope fractionation and csSRR in this case. Iron deficiency and nitrogen fixation by sulfate-reducing microbes may lead to the large observed S-isotope effects in some euxinic basins and various anoxic sediments. 相似文献
95.
A strong Cotton effect associated with the ring oxygen was studied in aromatic glycofuranosides. Phenyl and phenyl 1-thioglycofuranosides gave a strong band at 180 nm and 200–210 nm respectively, similar to the corresponding glycopyranosides, suggesting that the ring oxygen helicity rule can be extended to these aromatic glycofuranosides or the band can be used to determine their anomeric configurations and conformations. 相似文献
96.
Simple elastic network models of DNA were developed to reveal the structure-dynamics relationships for several nucleotide sequences. First, we propose a simple all-atom elastic network model of DNA that can explain the profiles of temperature factors for several crystal structures of DNA. Second, we propose a coarse-grained elastic network model of DNA, where each nucleotide is described only by one node. This model could effectively reproduce the detailed dynamics obtained with the all-atom elastic network model according to the sequence-dependent geometry. Through normal-mode analysis for the coarse-grained elastic network model, we exhaustively analyzed the dynamic features of a large number of long DNA sequences, approximately ∼150 bp in length. These analyses revealed positive correlations between the nucleosome-forming abilities and the inter-strand fluctuation strength of double-stranded DNA for several DNA sequences. 相似文献
97.
Early detection of dementia is crucial because it is the time when intervention is most effective. Therefore, a simple and short test is necessary for primary mass screening in community-based medical facilities. We developed the Cognitive Assessment for Dementia, iPad version (CADi) which consists of 10 simple questions and is self-administered. In this paper we present a revised version which improves the detection of dementia. Two questions of the CADi were replaced in the latest version (CADi2). We examined the validity and reliability of the CADi2 in 27 Alzheimer’s disease patients and age-matched healthy controls. The Alzheimer’s disease patients had lower CADi2 scores and longer total response times to questions compared to the controls. The CADi2 had high sensitivity (0.85−0.96) and specificity (0.81−0.93), and showed significant correlations with existing standard neuropsychological tests. Cronbach’s alpha analysis revealed moderate consistency of the CADi2. These results support the utility of the CADi2 for primary screening for dementia. 相似文献
98.
Atsushi Takeda Haruna Tamano Wakana Hashimoto Shuhei Kobuchi Hiroki Suzuki Taku Murakami Munekazu Tempaku Yuta Koike Paul A. Adlard Ashley I. Bush 《Molecular neurobiology》2018,55(10):7775-7788
The role of metallothioneins (MTs) in cognitive decline associated with intracellular Zn2+ dysregulation remains unclear. Here, we report that hippocampal MT induction defends cognitive decline, which was induced by amyloid β1–42 (Aβ1–42)-mediated excess Zn2+ and functional Zn2+ deficiency. Excess increase in intracellular Zn2+, which was induced by local injection of Aβ1–42 into the dentate granule cell layer, attenuated in vivo perforant pathway LTP, while the attenuation was rescued by preinjection of MT inducers into the same region. Intraperitoneal injection of dexamethasone, which increased hippocampal MT proteins and blocked Aβ1–42-mediated Zn2+ uptake, but not Aβ1–42 uptake, into dentate granule cells, also rescued Aβ1–42-induced impairment of memory via attenuated LTP. The present study indicates that hippocampal MT induction blocks rapid excess increase in intracellular Zn2+ in dentate granule cells, which originates in Zn2+ released from Aβ1–42, followed by rescuing Aβ1–42-induced cognitive decline. Furthermore, LTP was vulnerable to Aβ1–42 in the aged dentate gyrus, consistent with enhanced Aβ1–42-mediated Zn2+ uptake into aged dentate granule cells, suggesting that Aβ1–42-induced cognitive decline, which is caused by excess intracellular Zn2+, can more frequently occur along with aging. On the other hand, attenuated LTP under functional Zn2+ deficiency in dentate granule cells was also rescued by MT induction. Hippocampal MT induction may rescue cognitive decline under lack of cellular transient changes in functional Zn2+ concentration, while its induction is an attractive defense strategy against Aβ1–42-induced cognitive decline. 相似文献
99.
Miyuki Kusajima Shuhei Shima Moeka Fujita Kiwamu Minamisawa Fang-Sik Che Hiromoto Yamakawa 《Bioscience, biotechnology, and biochemistry》2018,82(9):1522-1526
A bacterial endophyte Azospirillum sp. B510 induces systemic disease resistance in the host without accompanying defense-related gene expression. To elucidate molecular mechanism of this induced systemic resistance (ISR), involvement of ethylene (ET) was examined using OsEIN2-knockdown mutant rice. Rice blast inoculation assay and gene expression analysis indicated that ET signaling is required for endophyte-mediated ISR in rice.
Abbreviations: ACC: 1-aminocyclopropane-1-carboxylic acid; EIN2: ethylene-insensitive protein 2; ET: ethylene; ISR: induced systemic resistance; JA: jasmonic acid; RNAi: RNA interference; SA: salicylic acid; SAR: systemic acquired resistance 相似文献
100.
Ryuji Tsunekawa Kengo Hanaya Shuhei Higashibayashi 《Bioscience, biotechnology, and biochemistry》2018,82(8):1316-1322
Fisetin and 2′,4′,6′-trihydroxydihyrochalcone 4′-O-β-neohesperidoside were synthesized from commercially available quercetin and naringin in five steps. The key steps are site-selective deacetylation and subsequent deoxygenation. The target molecules were obtained in 37% and 23% yields from the starting materials, respectively. 相似文献