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排序方式: 共有588条查询结果,搜索用时 15 毫秒
1.
James B Munro Roger B Altman Chang‐Shung Tung Kevin Y Sanbonmatsu Scott C Blanchard 《The EMBO journal》2010,29(4):770-781
A key intermediate in translocation is an ‘unlocked state’ of the pre‐translocation ribosome in which the P‐site tRNA adopts the P/E hybrid state, the L1 stalk domain closes and ribosomal subunits adopt a ratcheted configuration. Here, through two‐ and three‐colour smFRET imaging from multiple structural perspectives, EF‐G is shown to accelerate structural and kinetic pathways in the ribosome, leading to this transition. The EF‐G‐bound ribosome remains highly dynamic in nature, wherein, the unlocked state is transiently and reversibly formed. The P/E hybrid state is energetically favoured, but exchange with the classical P/P configuration persists; the L1 stalk adopts a fast dynamic mode characterized by rapid cycles of closure and opening. These data support a model in which P/E hybrid state formation, L1 stalk closure and subunit ratcheting are loosely coupled, independent processes that must converge to achieve the unlocked state. The highly dynamic nature of these motions, and their sensitivity to conformational and compositional changes in the ribosome, suggests that regulating the formation of this intermediate may present an effective avenue for translational control. 相似文献
2.
H. Furuya Yoh-ji Kukita Sukehisa Nagano Yasuyoshi Sakai Yoriaki Yamashita Hidenao Fukuyama Yuichiro Inatomi Yutaka Saito Ryoko Koike Shoji Tsuji Yasuyuki Fukumaki Kenshi Hayashi Takuro Kobayashi 《Human genetics》1997,100(3-4):450-456
We examined galactosylceramidase (GALC) cDNA in four Japanese patients with adult onset globoid cell leukodystrophy (Krabbe
disease; AO-GLD) by polymerase chain reaction/single-strand conformation polymorphism (PCR-SSCP) analysis, subsequent sequence
determination, and restriction enzyme digestion of PCR products. Initial symptoms were the onset of slowly progressive spastic
paraplegia from the middle of the second decade, and all patients had diminished GALC activity in their leukocytes. We identified
three missense mutations (I66M, G270D, L618S) and one exon-6 skipping (535– 573del). Two of the patients had only the I66M
mutant mRNA, and one only the G270D mutant mRNA. The fourth patient carried a compound heterozygous mutation of 535–573del
and L618S. To determine the enzymatic activities produced by these mutations, we constructed mutated GALC cDNAs and expressed
them in COS-1 cells. Three mutations, viz., G270D, L618S, and exon-6 skipping (535–573del), produced diminished GALC activity
as expected. The I66M mutation in the wild-type GALC cDNA(I289) had normal activity, but when this mutation and the V289 polymorphism
were introduced into the same allele, it had decreased activity. Thus, the combination of a unique mutation and polymorphism
causes conformational change in the GALC enzyme, resulting in low enzymatic activity. AO-GLD mutations, including those found
here, are located in the N-terminus (I66M, G270D, 535–573del) or C-terminus (L618S) of the GALC enzyme, whereas the reported
mutations in the infantile form (IF-GLD) are in the central domain. This difference in mutation sites may affect the clinical
features of GLD.
Received: 4 February 1997 / Accepted: 28 April 1997 相似文献
3.
Taihei Miyakawa Shoichi Katsuragi Ryoko Kuramoto 《Virchows Archiv. B, Cell pathology including molecular pathology》1988,56(1):21-24
Perivascular amyloid fibrils in the brains of patients with Alzheimer's disease have been examined by electron microscopy. The amyloid fibrils showed a hollow rod structure and consisted of globular substances. Each turn appeared to be composed of five globular subunits. These findings coincide with the ultrastructure of amyloid fibrils obtained from replicas made by a rapid freezing method. 相似文献
4.
Takayoshi Yamagishi Toshihiko Serikawa Ryoko Morita Shinichi Nakamura Shoki Nishida 《Microbiology and immunology》1976,20(5):397-403
TSN agar was applicable for enumeration of Clostridium perfringens in fecal samples of adults but not in those of infants. It was demonstrated using TSN agar that some healthy aged adults had persistently carried C. perfringens at levels ranging from 107 to 109, while some others ranged from 103 to 106 per ml volume of fecal sample although all of these adults had the same diets. In the test for agglutinability of isolates of C. perfringens collected from two elderly adults, a younger adult and a baby, it was demonstrated that most of the isolates obtained from an aged adult of high levels for 19 months belonged the same serotype, while rapid alteration of serotypes could be observed in three other persons with high or low levels. In spite of as many as 109 C. perfringens per ml of feces, no trace of α-toxin could be detected in the fecal samples. In in vitro tests, fecal suspension suppressed the production of α-toxin although it allowed the organism to grow sufficiently. 相似文献
5.
Kazuo GOTO Eri KUWAYAMA Ryoko NOZU Masami UENO Nobuhito HAYASHIMOTO 《Experimental Animals》2015,64(2):191-197
In this study, hypochlorous acid solution, a weak acid, provided as drinking water to
rats, was evaluated for its ability to eradicate and prevent Pseudomonas
aeruginosa infection, while monitoring its simultaneous effect on serum
biochemical variables and microbiota in the rat cecum. The results suggest that the
solution could not eliminate the bacteria in the experimentally infected rats; however,
the administration of a 10-parts-per-million (ppm) hypochlorous acid solution as drinking
water was effective in inhibiting horizontal spread of P. aeruginosa
infection among cage mates. Additionally, exposure to hypochlorous solution did not have
any effect on serum biochemical variables of the rat including levels of total
cholesterol, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline
phosphatase (ALP), albumin, total bilirubin, lipase, amylase, urea nitrogen, total
protein, calcium (Ca), phosphorus (P), sodium (Na), chlorine (Cl), except for potassium
(K) levels. The most frequently isolated bacteria in the rat cecum included species
belonging to Bacteroidales, Lactobacillus,
Clostridiales, Erysipelotrichaceae,
Akkermansia, Coriobacteriales, and
Firmicutes. The ratio of the terminal restriction fragment length
polymorphism (T-RFLP) peaks did not differ across rats administered with 5 and 10 ppm weak
acid solution as compared to the control group for any of the bacteria, except for
Erysipelotrichaceae and Firmicutes, where the ratio of
T-RFLP peaks was higher in the 5 ppm group for Erysipelotrichaceae and in
the 10 ppm group for Firmicutes than that in the control group
(P<0.01). The results suggest that the weak acid hypochlorous
solution could not eradicate P. aeruginosa completely from rats. The
solution was effective in preventing infection without affecting serum biochemical
variables; however, some of bacterial microbiota may have changed due to administration of
the solution. 相似文献
6.
7.
Application of chimeric glucanase comprising mutanase and dextranase for prevention of dental biofilm formation 下载免费PDF全文
Ryoko Otsuka Susumu Imai Takatoshi Murata Yoshiaki Nomura Masaaki Okamoto Hideaki Tsumori Erika Kakuta Nobuhiro Hanada Yasuko Momoi 《Microbiology and immunology》2015,59(1):28-36
Water‐insoluble glucan (WIG) produced by mutans streptococci, an important cariogenic pathogen, plays an important role in the formation of dental biofilm and adhesion of biofilm to tooth surfaces. Glucanohydrolases, such as mutanase (α‐1,3‐glucanase) and dextranase (α‐1,6‐glucanase), are able to hydrolyze WIG. The purposes of this study were to construct bi‐functional chimeric glucanase, composed of mutanase and dextranase, and to examine the effects of this chimeric glucanase on the formation and decomposition of biofilm. The mutanase gene from Paenibacillus humicus NA1123 and the dextranase gene from Streptococcus mutans ATCC 25175 were cloned and ligated into a pE‐SUMOstar Amp plasmid vector. The resultant his‐tagged fusion chimeric glucanase was expressed in Escherichia coli BL21 (DE3) and partially purified. The effects of chimeric glucanase on the formation and decomposition of biofilm formed on a glass surface by Streptococcus sobrinus 6715 glucosyltransferases were then examined. This biofilm was fractionated into firmly adherent, loosely adherent, and non‐adherent WIG fractions. Amounts of WIG in each fraction were determined by a phenol‐sulfuric acid method, and reducing sugars were quantified by the Somogyi–Nelson method. Chimeric glucanase reduced the formation of the total amount of WIG in a dose‐dependent manner, and significant reductions of WIG in the adherent fraction were observed. Moreover, the chimeric glucanase was able to decompose biofilm, being 4.1 times more effective at glucan inhibition of biofilm formation than a mixture of dextranase and mutanase. These results suggest that the chimeric glucanase is useful for prevention of dental biofilm formation. 相似文献
8.
Ryoko T. Ichiki Yooichi Kainoh Yoshifumi Yamawaki Satoshi Nakamura 《Entomologia Experimentalis et Applicata》2011,138(3):175-183
Some parasitoid flies exploit odors derived from plants as olfactory cues for locating the food plants of host insects, but the role of visual cues associated with plants remains largely unknown. The generalist tachinid Exorista japonica Townsend (Diptera: Tachinidae) is attracted to odors derived from maize plants [Zea mays L. (Poaceae)] infested by the larvae of Mythimna separata (Walker) (Lepidoptera: Noctuidae). In this study, we examined the effects of visual parameters on the olfactory attraction of female flies to host‐infested plants. A paper plant model of one of four colors (blue, green, yellow, or red) was placed in front of a host‐infested plant, which was hidden behind a mesh screen in a wind tunnel. The landing rate of females was significantly higher on the green plant model than on the other three models. When an achromatic plant model of one of four gray scales (white, light gray, dark gray, or black) was tested, the response rate of females was significantly higher towards the white model and decreased as the brightness of models decreased. Few female flies responded to the green plant model without odors of the host‐infested plants. When the four color plant models were placed together in a cage filled with odors of host‐infested plants, females remained significantly longer on the green model than on the other three models. These results showed that E. japonica females preferred the color green when odors of the host‐infested plants were present and suggest that E. japonica uses visual as well as olfactory cues to locate the host habitat. 相似文献
9.
Ayumu Sugiura Ryo Yonashiro Toshifumi Fukuda Nobuko Matsushita Shun Nagashima Ryoko Inatome Shigeru Yanagi 《Mitochondrion》2011,11(1):139-146
Expansion of a polyglutamine tract in ataxin-3 (polyQ) causes Machado–Joseph disease, a late-onset neurodegenerative disorder characterized by ubiquitin-positive aggregate formation. Several lines of evidence demonstrate that polyQ also accumulates in mitochondria and causes mitochondrial dysfunction. To uncover the mechanism of mitochondrial quality-control via the ubiquitin–proteasome pathway, we investigated whether MITOL, a novel mitochondrial ubiquitin ligase localized in the mitochondrial outer membrane, is involved in the degradation of pathogenic ataxin-3 in mitochondria. In this study, we used N-terminal-truncated pathogenic ataxin-3 with a 71-glutamine repeat (ΔNAT-3Q71) and found that MITOL promoted ΔNAT-3Q71 degradation via the ubiquitin–proteasome pathway and attenuated mitochondrial accumulation of ΔNAT-3Q71. Conversely, MITOL knockdown induced an accumulation of detergent-insoluble ΔNAT-3Q71 with large aggregate formation, resulting in cytochrome c release and subsequent cell death. Thus, MITOL plays a protective role against polyQ toxicity, and thereby may be a potential target for therapy in polyQ diseases. Our findings indicate a protein quality-control mechanism at the mitochondrial outer membrane via a MITOL-mediated ubiquitin–proteasome pathway. 相似文献
10.