全文获取类型
收费全文 | 329篇 |
免费 | 28篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 8篇 |
2017年 | 4篇 |
2016年 | 6篇 |
2015年 | 7篇 |
2014年 | 14篇 |
2013年 | 29篇 |
2012年 | 18篇 |
2011年 | 17篇 |
2010年 | 16篇 |
2009年 | 11篇 |
2008年 | 15篇 |
2007年 | 20篇 |
2006年 | 19篇 |
2005年 | 16篇 |
2004年 | 16篇 |
2003年 | 20篇 |
2002年 | 13篇 |
2001年 | 9篇 |
2000年 | 7篇 |
1999年 | 10篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 5篇 |
1995年 | 1篇 |
1993年 | 2篇 |
1992年 | 7篇 |
1991年 | 7篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1982年 | 2篇 |
1979年 | 2篇 |
1974年 | 1篇 |
1972年 | 2篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有357条查询结果,搜索用时 46 毫秒
31.
We theoretically study the antigenic drift of viruses within an infected host, as observed in human immunodeficiency virus
(HIV) and equine infectious anemia virus (EIAV) infections, assuming that a finite number of antigen-determining sites at
the viral envelop gene are responsible for the specific immune response. The pattern of antigen evolution becomes more complex
than that predicted from the previous one-dimensional antigen space models. If the viral growth rate is sufficiently large,
the demographic stochasticity for the fate of a new antigen mutant can be neglected. The high dimensionality in the way a
virus escapes the immune defense in genotype space could then causes a rapid increase in the antigenic diversity and the total
viral density, until finally the whole antigen genotypes are used up. The viral population is then driven to extinction in
a host by the enhanced immune response to all genotypes. In contrast, if the viral growth rate is moderate or small so that
only a small fraction of new antigen mutants can survive during the initial endangered period of random extinction, the viral
antigenic diversity and the total density remain bounded, thereby enabling them to persist for a prolonged period by shifting
the dominant antigen types. The phylogenetic pattern of antigen divergence is well characterized by the mean number of surviving
antigen mutants from an antigen genotype. The substitution rate at antigen-determining sites increases as the efficiency of
host immune response increases.
Received: 11 January 2000 / Accepted: 25 May 2000 相似文献
32.
Using a combination of column chromatography and gel electrophoresis,we have found that acid phosphatase in cotyledons of Vigna mungoseedlings is composed of at least six forms (Ia1, Ia2, Ib1,Ib2, IIa and IIb). We purified one of the major forms, Ia1,as a polypeptide of 53 kDa. Using an antiserum raised againstthe enzyme Ia1, we examined the immunological relationshipsbetween the multiple forms from cotyledons and the distributionof the enzyme in organs of maturing and germinating seeds. (Received December 25, 1989; Accepted July 11, 1990) 相似文献
33.
The nuclear pore complex (NPC) facilitates nucleocytoplasmic transport, a crucial process for various cellular activities. The NPC comprises ~30 nucleoporins and is well characterized in vertebrates and yeast. However, only eight plant nucleoporins have been identified, and little information is available about the complete molecular structure of plant NPCs. In this study, an interactive proteomic approach was used to identify Arabidopsis thaliana nucleoporins. A series of five cycles of interactive proteomic analysis was performed using green fluorescent protein (GFP)-tagged nucleoporins. The identified nucleoporins were then cloned and subcellular localization analyses were performed. We found that the plant NPC contains at least 30 nucleoporins, 22 of which had not been previously annotated. Surprisingly, plant nucleoporins shared a similar domain organization to their vertebrate (human) and yeast (Saccharomyces cerevisiae) counterparts. Moreover, the plant nucleoporins exhibited higher sequence homology to vertebrate nucleoporins than to yeast nucleoporins. Plant NPCs lacked seven components (NUCLEOPORIN358 [Nup358], Nup188, Nup153, Nup45, Nup37, NUCLEAR DIVISION CYCLE1, and PORE MEMBRANE PROTEIN OF 121 kD) that were present in vertebrate NPCs. However, plants possessed a nucleoporin, Nup136/Nup1, that contained Phe-Gly repeats, and sequence analysis failed to identify a vertebrate homolog for this protein. Interestingly, Nup136-GFP showed greater mobility on the nuclear envelope than did other nucleoporins, and a Nup136/Nup1 deficiency caused various defects in plant development. These findings provide valuable new information about plant NPC structure and function. 相似文献
34.
Y. Sato S. Miyai D. Haraguchi S. Ohno T. Kohama K. Kawamura M. Yamagishi 《Journal of Applied Entomology》2010,134(4):303-312
The West Indian sweetpotato weevil Euscepes postfasciatus (Fairmaire) is a major pest of the sweet potato Ipomoea batatas (L.) Lam. and this weevil is a target of an eradication program using the Sterile Insect Technique in Okinawa Prefecture, Japan. Understanding the population ecology is essential in the planning of an eradication program; hence, a host‐plant infestation survey and light trap survey have been conducted to monitor the population dynamics of the weevil on Kume Island (Okinawa Prefecture), which is the target area of the trial weevil eradication project. Seasonal tendencies of weevil density were found in these field surveys, but the tendency found in the host‐plant infestation survey was not seen every year, and the effectiveness of the light trap is somewhat suspect. To confirm the reliability of the tendency observed in these field surveys, the present study attempted to explain the tendency by a seasonal temperature change using a temperature‐based model of weevil population dynamics. The seasonal changes of weevil density differed according to host plants and host‐plant fields. The seasonal changes of weevil density inside the host plant Ipomoea indica and outside the host plants in I. indica fields were consistent with those predicted by the model. However, those inside the host plant Ipomoea pes‐caprae in the host‐plant infestation survey were contrary to the predicted ones, and those observed outside host plants in I. pes‐caprae fields by the light trap survey were not in good agreement with the predicted ones. It was concluded that the seasonal change of the weevil density observed in I. indica and I. indica fields can be explained by a seasonal temperature change, but factors other than seasonal temperature change are needed to explain those in I. pes‐caprae and I. pes‐caprae fields. 相似文献
35.
The aim of our study was to examine the effect of mass‐rearing, in which there is no exposure to predators, on antipredator traits of insects for improving sterile insect technique programs. The duration of death‐feigning (antipredator behaviour) in sweet potato weevil Cylas formicarius (Summers) (Coleoptera: Brentidae) after mass‐rearing for 71 generations were compared with those in wild strain. There was no significant difference in the duration of death‐feigning between wild and mass‐reared strains. This indicated that the death‐feigning behaviour of mass‐reared strain was maintained for 71 generations even in the absence of predators. We discuss the reasons why death‐feigning behaviour is maintained after mass‐rearing. 相似文献
36.
37.
For the synthesis of 2',3' -didehydro-3' -deoxy-4' -C-ethynylthymidine (8: 4' -Ed4T), a recently reported promising anti-HIV agent, a new approach was developed. Since treatment of 1-(2,5-dideoxy-beta-l-glycero-pent-4-enofuranosyl)thymine with Pb(OBz)4 allowed the introduction of a 4'-benzoyloxy leaving group, nucleophilic substitution at the 4' -position became feasible for the first time. Thus, reaction between the 4'-benzoyloxy derivative (11) and Me3SiC identical with CAl(Et)Cl as a nucleophile led to the isolation of the desired 4'-"down"-ethynyl derivative (15) stereoselectively in 62% yield. 相似文献
38.
The usefulness of semi‐solid medium in the isolation of highly virulent Leptospira strains from wild rats in an urban area of Fukuoka,Japan 下载免费PDF全文
Mitsumasa Saito Sharon Y. A. M. Villanueva Toshiyuki Masuzawa Yusuke Haraguchi Shuhei Ita Satoshi Miyahara Ryo Ozuru Takayoshi Yamaguchi Michinobu Yoshimura Mami Ikejiri Natsumi Aramaki Muhammad Yunus Amran Lisa Tenriesa Muslich Ken‐ichiro Iida Yasutake Yanagihara Nina G. Gloriani Shin‐ichi Yoshida 《Microbiology and immunology》2015,59(6):322-330
Leptospirosis is a worldwide zoonosis. The importance of urban leptospirosis is recognized in Japan: urban rats carry pathogenic leptospires and people acquire these pathogens through contact with surface water or soil contaminated by the urine of the infected animals. To determine the current Leptospira carriage rate in urban rats, 29 wild rats were trapped in the central area of Fukuoka and strains isolated from their kidneys and urine analyzed. When semi‐solid Korthof's medium containing 0.1% agar was used for isolation, 72.2% and 30.8% of the kidney and urine cultures, respectively, were found to be Leptospira‐positive. The isolates belonged to Leptospira interrogans, and were classified into two groups (serogroups Pomona and Icterohaemorrhagiae) based on the results of gyrB sequence analysis and microscopic agglutination testing (MAT). Strains belonging to serogroup Icterohemorrhagiae grew well in liquid medium. On the other hand, serogroup Pomona isolates multiplied very little in liquid medium, but did grow in a semi‐solid medium. Although strains belonging to serogroup Pomona have not been recognized as native to Japan, this strain may be widely distributed in urban rats. Representative strains from each group were found to be highly pathogenic to hamsters. Our findings should serve as a warning that it is still possible to become infected with leptospires from wild rats living in inner cities of Japan. Furthermore, the use of semi‐solid medium for culture will improve the isolation rate of leptospires from the kidneys of wild rats. 相似文献
39.
Norikuni Kumano Takashi Kuriwada Keiko Shiromoto Dai Haraguchi Tsuguo Kohama 《Population Ecology》2011,53(1):111-117
Persistent mating attempts by males (sexual harassment) are frequently observed among animals. For females, resisting persistent
males can be costly because vigorous resistance increases both energy expenditure and the possibility of injury. Although
one tactic for coping with male harassment is to cease resistance and mate with the persistent partner, the females of several
species are able to prevent the fertilization of their egg(s) despite copulation. In this study, we used three different sex
ratios to investigate whether a male’s mating persistence affects his mating success in the West Indian sweet potato weevil
Euscepes postfasciatus, in which males mount females both before and after copulation. Consistent with our predictions, we found that female weevils
resist and manipulate sperm transfer either before or during copulation according to their preferences. Female weevils were
able to reject the sperm of persistent males despite having copulated with them. However, neither copulation and/or post-copulatory
mounting affected insemination success. We speculate that the intensive resistance shown by females before copulation may
induce mechanical sterility in E. postfasciatus. 相似文献
40.
Matsumaru D Haraguchi R Miyagawa S Motoyama J Nakagata N Meijlink F Yamada G 《PloS one》2011,6(1):e16260