全文获取类型
收费全文 | 550篇 |
免费 | 66篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 17篇 |
2020年 | 10篇 |
2019年 | 7篇 |
2018年 | 7篇 |
2017年 | 7篇 |
2016年 | 17篇 |
2015年 | 16篇 |
2014年 | 17篇 |
2013年 | 58篇 |
2012年 | 20篇 |
2011年 | 24篇 |
2010年 | 22篇 |
2009年 | 7篇 |
2008年 | 30篇 |
2007年 | 22篇 |
2006年 | 36篇 |
2005年 | 47篇 |
2004年 | 29篇 |
2003年 | 22篇 |
2002年 | 16篇 |
2001年 | 16篇 |
2000年 | 9篇 |
1999年 | 20篇 |
1998年 | 17篇 |
1997年 | 8篇 |
1996年 | 4篇 |
1995年 | 10篇 |
1994年 | 10篇 |
1993年 | 5篇 |
1992年 | 8篇 |
1991年 | 3篇 |
1990年 | 11篇 |
1989年 | 9篇 |
1988年 | 11篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1971年 | 2篇 |
1970年 | 3篇 |
1968年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有616条查询结果,搜索用时 15 毫秒
131.
Electron microscopic observation of new transposable elements inserted into P22 phage genome from R plasmids 总被引:1,自引:0,他引:1
By using phage P22spl, a deletion mutant of phage P22, the structures of two new transposons on P22 genomes were studied by the electron microscopic heteroduplex method. One of these was the Cm (chloramphenicol) transposon derived from an R plasmid, NR1, and the other the Km (kanamycin) transposon frin obr502. the heteroduplex between P22 phage DNAs with and without the Cm transposon revealed that the Cm transposon was similar in structure to the Tn9 element, a well-known Cm transposon derived from the R plasmid pMS14. On the other hand, the Km transposon of pNR502 was quite different in structure from other Km transposons reported previously. This transposon consists of a 6.8 kilobase (kb) segment of DNA, in which a short inverted repeat is contained. The heteroduplex experiments showed that a 4.5 kb segment of DNA was deleted from the P22 genome in the P22spl genome. Because of a shorter unit length of the genome, phage P22spl is considered to be useful of assaying various kinds of transposable elements. 相似文献
132.
Isolation and Characterization of a New Generalized Transducing Bacteriophage Different from Pl in Escherichia coli
下载免费PDF全文
![点击此处可从《Journal of virology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Katsutoshi Mise 《Journal of virology》1971,7(1):168-175
A new generalized transducing bacteriophage in the Escherichia coli system was isolated and characterized. This phage, designated D108, makes clear plaques on E. coli K-10, K-12, K-12(P1kc), K-12(D6), B/r, C, and 15 T(-), and Shigella dysenteriae. The plaque of phage D108 is larger in size than that of phage P1kc. Electron-microscopic observation revealed that phages D108 and P1kc are morphologically different from each other, suggesting that phage D108 belongs to a phage group different from phage P1. The fact that all of the 10 markers tested were transduced by phage D108 indicates that this phage is a generalized transducing phage in the E. coli system. The transduction frequency by phage D108 of chromosomal markers and of a drug resistance factor (R factor) ranged from 2 x 10(-6) to 3 x 10(-8) and 3 x 10(-9) to 6 x 10(-10) per phage, respectively. The cotransduction frequency of the thr and leu markers was 2.8% for phage P1kc and 1.5% for phage D108. The CM and TC markers (chloramphenicol-resistant and tetracycline-resistant markers, respectively) of the R factor were not cotransduced by phage D108, but the markers were generally cotransduced by phage P1kc. The results suggest that the transducing particle of phage D108 contains a smaller amount of host deoxyribonucleic acid than does phage P1kc. 相似文献
133.
Temperature-sensitive Chloramphenicol Acetyltransferase from Escherichia coli Carrying Mutant R Factors 总被引:5,自引:3,他引:2
Bacteria carrying temperature-sensitive mutant R factors for chloramphenicol resistance were isolated. In the presence of chloramphenicol, these bacteria grew at 34 C but not at 43 C. The mutations in the chloramphenicol resistance gene of the R factors affected neither the resistance of the bacteria to dihydrostreptomycin and tetracycline nor the stability of the R factors at 43 C. The chloramphenicol acetyltransferase obtained from Escherichia coli K-12 carrying the mutant R factors was heat-labile as compared with that from a strain carrying the wild-type R factor. We could not find chloramphenicol acetyltransferase activity in 17 chloramphenicol-sensitive and 5 -resistant strains (selected in vitro) of E. coli examined. The results strongly suggest that the chloramphenicol resistance gene of the R factors is the structural gene of the chloramphenicol acetyltransferase rather than the genome controlling the expression of a chromosomal determinant for the enzyme. Furthermore, the studies confirm that the existence of the chloramphenicol acetyltransferase is the primary cause of chloramphenicol resistance of bacteria carrying the R factor. Both the enzyme activity producing the monoacetyl derivative from chloramphenicol and the subsequent formation of the diacetate from the monoacetyl product were heat-labile to the same degree. The results suggest that only one enzyme participates in two steps of chloramphenicol acetylation. 相似文献
134.
Yuji Murakami Takashi Furusato Chiaki Kato Noriyuki Habuka Toshiaki Kudo Koki Horikoshi 《Applied microbiology and biotechnology》1989,30(6):619-623
Summary In order to develop a more useful system for extracellular protein production from Escherichia coli, we have constructed the new excretion vectors pEAP82-1, pEAP82-2, and pEAP82-3. These vectors have, respectively, a single, double, and triple penicillinase promoter upstream of a penicillinase structural gene; E. coli HB101 carrying pEAP82-2 or pEAP82-3 produced respectively, about twice or three times as much penicillinase protein than that produced by E. coli carrying pEAP82-1, and 70% to 80% of the protein was excreted into the culture medium. The E. coli carrying pEAP82-3 was cultivated at various temperatures and it was observed that the optimum for extracellular penicillinase production was 30°–37°C. Using this multi-promoter excretion system, the amount of extracellular production of human growth hormone was increased by several fold as observed with penicillinase excretion. 相似文献
135.
Path analysis of family resemblance for plasma glucose concentration, 2 h after an oral glucose challenge, failed to detect significant genetic heritability. There were no intergenerational differences and marital resemblance was moderate. Over one-third of sibling environmental similarity was due to non-inherited factors. Cultural inheritance was very strong, tending to mimic genetic inheritance, and cultural heritability was considerable. Measures of obesity were included in the environmental index, an estimate of familial environment, in this analysis, for comparability with previous studies. Since obesity appears, in part, to be a heritable trait, in future studies a bivariate approach to family resemblance for both glucose tolerance and obesity could yield important additional insight. 相似文献
136.
Fumiyasu Fukumori Kazuo Ohishi Toshiaki Kudo Koki Horikoshi 《FEMS microbiology letters》1987,48(1-2):65-68
Abstract A 5.7-kb Eco RI DNA fragment has been isolated from Bacillus sp. strain N-4 chromosome DNA. This fragment contained both the pNK1-encoded cellulase ( celB ) gene and the pNK2-encoded cellulase ( celA ) gene which were highly homologous [13]. These results demonstrate the tandem location of these genes on the chromosomal DNA. The homologous sequence, which may play an important role for the gene duplication, were observed 5' upstream of the celA gene, between the celA and celB genes, and 3' downstream from the celB gene. 相似文献
137.
Pagotto João Paulo Alves Pessoa Leonardo Antunes Goulart Erivelto Mise Fábio Teruo Ortega Jean Carlo Gonçalves Landgraf Guilherme Okuda 《Hydrobiologia》2022,849(10):2299-2316
Hydrobiologia - Human activities change the environmental conditions of streams and alter their assemblages. However, the environmental factors associated with the change in the ecomorphological... 相似文献
138.
Ivana Čabarkapa Radmilo Čolović Olivera Đuragić Sanja Popović Bojana Kokić Dubravka Milanov 《Biofouling》2019,35(3):361-375
The aim of the present study was to determine the bioactive compounds in four essential oils (EO’s) from Origanum heracleoticum, Origanum vulgare, Thymus vulgaris and Thymus serpyllum and to assess their antimicrobial and anti-biofilm activity against Salmonella Enteritidis. Strains were previously characterized depending on the expression of the extracellular matrix components cellulose and curli fimbriae as rdar (red, dry and rough) and bdar morphotype (brown, dry and rough). This study revealed that the EO’s and EOC’s (carvacrol and thymol) investigated showed inhibition of biofilm formation at sub-minimum inhibitory concentration. Comparing the efficacy of EO’s and EOC’s in the inhibition of biofilm formation between the strains with different morphotype (rdar and bdar) did not show a statistically significant difference. Results related to the effectiveness of EO’s and EOC’s (the essential oil components, carvacrol and thymol) on eradication of preformed 48?h old biofilms indicated that biofilm reduction occurred in a dose-dependent manner over time. 相似文献
139.
We have purified a new violet pigment derived from Shewanella violacea DSS12 to determine its chemical structure. The pigment colored blue in tetrahydrofuran (THF) or chloroform and showed a broad
absorption spectrum from 500 to 700 nm. X-ray diffraction analysis of single crystals showed that the chemical structure of
this pigment was 5,5′-didodecylamino-4,4′-dihydroxy-3,3′-diazodiphenoquinone-(2,2′), containing the same chromophore as an
indigoidine known as microbial blue pigment. The violet color of this pigment was due to hypsochromic shift (blue shift) caused
by the side-by-side orientation of this pigment molecule, revealed by X-ray structural analyses of a single crystal.
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
140.
Development of a general‐purpose method for cell purification using Cre/loxP‐mediated recombination
下载免费PDF全文
![点击此处可从《Genesis (New York, N.Y. : 2000)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Shunsuke Kuroki Mika Akiyoshi Ko Ideguchi Satsuki Kitano Hitoshi Miyachi Michiko Hirose Nathan Mise Kuniya Abe Atsuo Ogura Makoto Tachibana 《Genesis (New York, N.Y. : 2000)》2015,53(6):387-393
A mammalian body is composed of more than 200 different types of cells. The purification of a certain cell type from tissues/organs enables a wide variety of studies. One popular cell purification method is immunological isolation, using antibodies against specific cell surface antigens. However, this is not a general‐purpose method, since suitable antigens have not been found in certain cell types, including embryonic gonadal somatic cells and Sertoli cells. To address this issue, we established a knock‐in mouse line, named R26 KI, designed to express the human cell surface antigen hCD271 through Cre/loxP‐mediated recombination. First, we used the R26 Kl mouse line to purify embryonic gonadal somatic cells. Gonadal somatic cells were purified from the R26 KI; Nr5a1‐Cre‐transgenic (tg) embryos almost equally as efficiently as from Nr5a1‐hCD271‐tg embryos. Second, we used the R26 KI mouse line to purify Sertoli cells successfully from R26 KI; Amh‐Cre‐tg testes. In summary, we propose that the R26 KI mouse line is a powerful tool for the purification of various cell types. genesis 53:387–393, 2015. © 2015 Wiley Periodicals, Inc. 相似文献