全文获取类型
收费全文 | 565篇 |
免费 | 32篇 |
国内免费 | 1篇 |
出版年
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 7篇 |
2016年 | 6篇 |
2015年 | 17篇 |
2014年 | 25篇 |
2013年 | 32篇 |
2012年 | 35篇 |
2011年 | 27篇 |
2010年 | 23篇 |
2009年 | 17篇 |
2008年 | 37篇 |
2007年 | 29篇 |
2006年 | 27篇 |
2005年 | 19篇 |
2004年 | 34篇 |
2003年 | 24篇 |
2002年 | 35篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1999年 | 16篇 |
1998年 | 8篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 7篇 |
1994年 | 4篇 |
1992年 | 12篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 9篇 |
1986年 | 7篇 |
1985年 | 3篇 |
1984年 | 8篇 |
1983年 | 3篇 |
1982年 | 9篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 6篇 |
1977年 | 13篇 |
1976年 | 6篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 6篇 |
1972年 | 2篇 |
1971年 | 4篇 |
1970年 | 5篇 |
1969年 | 5篇 |
1968年 | 2篇 |
1967年 | 2篇 |
1966年 | 4篇 |
排序方式: 共有598条查询结果,搜索用时 15 毫秒
541.
Ling Chin Hwang Anthony G Vecchiarelli Yong‐Woon Han Michiyo Mizuuchi Yoshie Harada Barbara E Funnell Kiyoshi Mizuuchi 《The EMBO journal》2013,32(9):1238-1249
DNA segregation ensures the stable inheritance of genetic material prior to cell division. Many bacterial chromosomes and low‐copy plasmids, such as the plasmids P1 and F, employ a three‐component system to partition replicated genomes: a partition site on the DNA target, typically called parS, a partition site binding protein, typically called ParB, and a Walker‐type ATPase, typically called ParA, which also binds non‐specific DNA. In vivo, the ParA family of ATPases forms dynamic patterns over the nucleoid, but how ATP‐driven patterning is involved in partition is unknown. We reconstituted and visualized ParA‐mediated plasmid partition inside a DNA‐carpeted flowcell, which acts as an artificial nucleoid. ParA and ParB transiently bridged plasmid to the DNA carpet. ParB‐stimulated ATP hydrolysis by ParA resulted in ParA disassembly from the bridging complex and from the surrounding DNA carpet, which led to plasmid detachment. Our results support a diffusion‐ratchet model, where ParB on the plasmid chases and redistributes the ParA gradient on the nucleoid, which in turn mobilizes the plasmid. 相似文献
542.
Yoshie S. Weems Aaron Raney John Pang Tracie Uchima Esther Lennon Drew Johnson Torrence M. Nett Ronald D. Randel Charles W. Weems 《Theriogenology》2013
The objective of this study was to determine whether prostaglandin E1 (PGE1) or prostaglandin E2 (PGE2) prevents premature luteolysis in ewes when progesterone is given during the first 6 days of the estrous cycle. Progesterone (3 mg in oil, im) given twice daily from Days 1 to 6 (estrus = Day 0) in ewes decreased (P < 0.05) luteal weights on Day 10 postestrus. Plasma progesterone concentrations differed (P < 0.05) among the treatment groups; toward the end of the experimental period, concentrations in jugular venous blood decreased (P < 0.05) compared with the other treatment groups. Plasma progesterone concentrations in ewes receiving PGE1 or PGE1 + progesterone were greater (P < 0.05) than in vehicle controls or in ewes receiving PGE2 or PGE2 or PGE2 + progesterone. Chronic intrauterine treatment with PGE1 or PGE2 prevented (P < 0.05) decreases in plasma progesterone concentrations, luteal weights, and the proportion of luteal unoccupied and occupied LH receptors on Day 10 postestrus in ewes given exogenous progesterone, but did not affect (P > 0.05) concentrations of PGF2α in inferior vena cava blood. Progesterone given on Days 1 to 6 in ewes advanced (P < 0.05) increases in PGF2α in inferior vena cava blood. We concluded that PGE1 or PGE2 prevented progesterone-induced premature luteolysis by suppressing loss of luteal LH receptors (both unoccupied and occupied). 相似文献
543.
Yoshiki Fujii Kazutaka Kitaura Takaji Matsutani Kenji Shirai Satsuki Suzuki Tomohiko Takasaki Kenichi Kumagai Yoshie Kametani Takashi Shiina Shuji Takabayashi Hideki Katoh Yoshiki Hamada Ichiro Kurane Ryuji Suzuki 《PloS one》2013,8(2)
The common marmoset (Callithrix jacchus) is considered a novel experimental animal model of non-human primates. However, due to antibody unavailability, immunological and pathological studies have not been adequately conducted in various disease models of common marmoset. Quantitative real-time PCR (qPCR) is a powerful tool to examine gene expression levels. Recent reports have shown that selection of internal reference housekeeping genes are required for accurate normalization of gene expression. To develop a reliable qPCR method in common marmoset, we used geNorm applets to evaluate the expression stability of eight candidate reference genes (GAPDH, ACTB, rRNA, B2M, UBC, HPRT, SDHA and TBP) in various tissues from laboratory common marmosets. geNorm analysis showed that GAPDH, ACTB, SDHA and TBP were generally ranked high in stability followed by UBC. In contrast, HPRT, rRNA and B2M exhibited lower expression stability than other genes in most tissues analyzed. Furthermore, by using the improved qPCR with selected reference genes, we analyzed the expression levels of CD antigens (CD3ε, CD4, CD8α and CD20) and cytokines (IL-1β, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12β, IL-13, IFN-γ and TNF-α) in peripheral blood leukocytes and compared them between common marmosets and humans. The expression levels of CD4 and IL-4 were lower in common marmosets than in humans whereas those of IL-10, IL-12β and IFN-γ were higher in the common marmoset. The ratio of Th1-related gene expression level to that of Th2-related genes was inverted in common marmosets. We confirmed the inverted ratio of CD4 to CD8 in common marmosets by flow cytometric analysis. Therefore, the difference in Th1/Th2 balance between common marmosets and humans may affect host defense and/or disease susceptibility, which should be carefully considered when using common marmoset as an experimental model for biomedical research. 相似文献
544.
Romano Dallai Ryuichiro Machida Yoshie Jintsu Francesco Frati Pietro Lupetti 《Zoomorphology》2007,126(1):53-59
The sperm structure of two species of Embioptera, Embia savignyi Westwood 1837 and Aposthonia japonica (Okajima 1926), was studied. Spermatozoa of both species exhibit a monolayered acrosome and a layer of material surrounding
the sperm cells for most of their length. The presence of a 9+9+2 axoneme provided with accessory microtubules with 16 protofilaments,
two accessory bodies and two crystallized mitochondrial derivatives are characters shared with other polyneopteran taxa. The
supposed close relationship between Embioptera and Phasmatodea is not supported by characters of the sperm ultrastructure. 相似文献
545.
Sayaka Yamaguchi Ayako Sano Midori Hiruma Michiko Murata Takashi Kaneshima Yoshiteru Murata Hideo Takahashi Sana Takahashi Yoko Takahashi Hiroji Chibana Hidemi Touyama Nguyen Thi Thanh Ha Yasutomo Nakazato You Uehara Morihiko Hirakawa Yoshimi Imura Yoshie Terashima Yasuhiro Kawamoto Keji Takahashi Kazutoshi Sugiyama Masataro Hiruma Masaru Murakami Atsushi Hosokawa Hiroshi Uezato 《Mycopathologia》2014,178(1-2):135-143
We investigated 793 bird combs [645 chickens and 148 fighting cocks (Shamo)] to determine the prevalence of dermatophytes and their related fungal species. The targeted fungal species were recovered from 195 of the 793 examined birds (24.6 %). Prevalence ratios were compared in temperate (the mainland) and subtropical (Nansei Islands) areas, genders, strains, breeding scale (individual and farm), and housing system (in cage and free ranging). The frequency of the fungal species in the mainland, males, fighting cocks, breeding scale by individual nursing, and free-range housing system exhibited significantly higher positive ratios than that in the other groups. A total of 224 dermatophytes and related species were isolated, including 101 Arthroderma (Ar.) multifidum, 83 Aphanoascus (Ap.) terreus, five Uncinocarpus queenslandicus, two U. reesii, two Ap. pinarensis, one Amauroascus kuehnii, one Ar. simii, one Gymnoascus petalosporus, one Microsporum gallinae, and 28 Chrysosporium-like (Chrysosporium spp.) isolates, which were identified using internal transcribed spacer regions of ribosomal RNA gene sequences. The predominant fungal species in the mainland was Ap. terreus and that in the Nansei Islands was Ar. multifidum. Pathogenic fungal species to humans and animals were limited to M. gallinae and Ar. simii, which corresponded to 0.025 % of the isolates in this study. 相似文献
546.
Takehiro Miyazaki Yoshie Ikeda Ikue Kubo Saeri Suganuma Nastumi Fujita Makiko Itakura Tae Hayashi Shuji Takabayashi Hideki Katoh Yukio Ohira Masahiro Sato Motoko Noguchi Toshinobu Tokumoto 《Mammalian genome》2014,25(7-8):317-326
Spontaneous testicular teratomas (STTs) composed by various kinds of tissues are derived from primordial germ cells (PGCs) in the fetal testes of the mouse. In contrast, intra-testicular grafts of the mouse strain (129/Sv-Ter (+/+)) fetal testes possessed the ability to develop the experimental testicular teratomas (ETTs), indistinguishable from the STTs at a morphological level. In this study, linkage analysis was performed for exploration of possible candidate genes involving in ETT development using F2 intercross fetuses derived from [LTXBJ × 129/Sv-Ter (+/+)] F1 hybrids. Linkage analysis with selected simple sequence length polymorphisms along chromosomes 18 and 19, which have been expected to contain ETT-susceptibility loci, demonstrated that a novel recessive candidate gene responsible for ETT development is located in 1.1 Mb region between the SSLP markers D18Mit81 and D18Mit184 on chromosome 18 in the 129/Sv-Ter (+/+) genetic background. Since this locus is different from the previously known loci (including Ter, pgct1, and Tgct1) for STT development, we named this novel gene “experimental testicular teratoma 1 (ett1)”. To resolve the location of ett1 independently from other susceptibility loci, ett1 loci was introduced in a congenic strain in which the distal segment of chromosome 18 in LTXBJ strain mice had been replaced by a 1.99 Mbp genomic segment of the 129/Sv-Ter (+/+) mice. Congenic males homozygous for the ett1 loci were confirmed to have the ability to form ETTs, indicating that this locus contain the gene responsible for ETTs. We listed candidate genes included in this region, and discussed about their possible involvement in induction of ETTs. 相似文献
547.
Minoru Nagano Toshiki Ishikawa Yoshie Ogawa Mitsuru Iwabuchi Akari Nakasone Ko Shimamoto Hirofumi Uchimiya Maki Kawai-Yamada 《Planta》2014,240(1):77-89
Bax inhibitor-1 (BI-1) is a widely conserved cell death suppressor localized in the endoplasmic reticulum membrane. Our previous results revealed that Arabidopsis BI-1 (AtBI-1) interacts with not only Arabidopsis cytochrome b 5 (Cb5), an electron transfer protein, but also a Cb5-like domain (Cb5LD)-containing protein, Saccharomyces cerevisiae fatty acid 2-hydroxylase 1, which 2-hydroxylates sphingolipid fatty acids. We have now found that AtBI-1 binds Arabidopsis sphingolipid Δ8 long-chain base (LCB) desaturases AtSLD1 and AtSLD2, which are Cb5LD-containing proteins. The expression of both AtBI-1 and AtSLD1 was increased by cold exposure. However, different phenotypes were observed in response to cold treatment between an atbi-1 mutant and a sld1sld2 double mutant. To elucidate the reasons behind the difference, we analyzed sphingolipids and found that unsaturated LCBs in atbi-1 were not altered compared to wild type, whereas almost all LCBs in sld1sld2 were saturated, suggesting that AtBI-1 may not be necessary for the desaturation of LCBs. On the other hand, the sphingolipid content in wild type increased in response to low temperature, whereas total sphingolipid levels in atbi-1 were unaltered. In addition, the ceramide-modifying enzymes AtFAH1, sphingolipid base hydroxylase 2 (AtSBH2), acyl lipid desaturase 2 (AtADS2) and AtSLD1 were highly expressed under cold stress, and all are likely to be related to AtBI-1 function. These findings suggest that AtBI-1 contributes to synthesis of sphingolipids during cold stress by interacting with AtSLD1, AtFAH1, AtSBH2 and AtADS2. 相似文献
548.
Pseudomonad Cyclopentadecanone Monooxygenase Displaying an Uncommon Spectrum of Baeyer-Villiger Oxidations of Cyclic Ketones 总被引:3,自引:0,他引:3
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Hiroaki Iwaki Shaozhao Wang Stephan Grosse Hlne Bergeron Ayako Nagahashi Jittiwud Lertvorachon Jianzhong Yang Yasuo Konishi Yoshie Hasegawa Peter C. K. Lau 《Applied microbiology》2006,72(4):2707-2720
Baeyer-Villiger monooxygenases (BVMOs) are biocatalysts that offer the prospect of high chemo-, regio-, and enantioselectivity in the organic synthesis of lactones or esters from a variety of ketones. In this study, we have cloned, sequenced, and overexpressed in Escherichia coli a new BVMO, cyclopentadecanone monooxygenase (CpdB or CPDMO), originally derived from Pseudomonas sp. strain HI-70. The 601-residue primary structure of CpdB revealed only 29% to 50% sequence identity to those of known BVMOs. A new sequence motif, characterized by a cluster of charged residues, was identified in a subset of BVMO sequences that contain an N-terminal extension of ~60 to 147 amino acids. The 64-kDa CPDMO enzyme was purified to apparent homogeneity, providing a specific activity of 3.94 μmol/min/mg protein and a 20% yield. CPDMO is monomeric and NADPH dependent and contains ~1 mol flavin adenine dinucleotide per mole of protein. A deletion mutant suggested the importance of the N-terminal 54 amino acids to CPDMO activity. In addition, a Ser261Ala substitution in a Rossmann fold motif resulted in an improved stability and increased affinity of the enzyme towards NADPH compared to the wild-type enzyme (Km = 8 μM versus Km = 24 μM). Substrate profiling indicated that CPDMO is unusual among known BVMOs in being able to accommodate and oxidize both large and small ring substrates that include C11 to C15 ketones, methyl-substituted C5 and C6 ketones, and bicyclic ketones, such as decalone and β-tetralone. CPDMO has the highest affinity (Km = 5.8 μM) and the highest catalytic efficiency (kcat/Km ratio of 7.2 × 105 M−1 s−1) toward cyclopentadecanone, hence the Cpd designation. A number of whole-cell biotransformations were carried out, and as a result, CPDMO was found to have an excellent enantioselectivity (E > 200) as well as 99% S-selectivity toward 2-methylcyclohexanone for the production of 7-methyl-2-oxepanone, a potentially valuable chiral building block. Although showing a modest selectivity (E = 5.8), macrolactone formation of 15-hexadecanolide from the kinetic resolution of 2-methylcyclopentadecanone using CPDMO was also demonstrated. 相似文献
549.
550.
Latitudinal variation in suppression of flower bud formation at high temperature in four native dandelions (Taraxacum spp.) with different distributions and genetic structures in Japan
下载免费PDF全文
![点击此处可从《Plant Species Biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Fumio Yoshie 《Plant Species Biology》2017,32(1):54-65
The control of the response of flowering to temperature plays a key role in successful range‐expansion of plants. A previous study showed that the suppression of flower‐bud formation at high temperature in Taraxacum officinale decreases genetically with latitude from north to south in Japan. The present study investigated whether similar trait variation occurs among populations of native Taraxacum species in Japan. Seedlings of T. albidum (a low‐ and mid‐latitude allopolyploid), T. japonicum (a mid‐latitude diploid) and T. venustum (a high‐latitude autopolyploid) were grown at three temperatures. Time to flower‐bud appearance increased with temperature in T. japonicum and T. venustum, but did not increase in T. albidum. Time to flower‐bud appearance did not differ significantly among the three species at 14°C, but it was shorter in T. albidum than in the other two species at 19°C and 24°C. The early appearance of buds of T. albidum was confirmed by another experiment in which plants of 18 populations from the three species and T. platycarpum (a mid‐latitude diploid) grown at 19°C were used. The results clearly indicate that high‐temperature suppression of flower‐bud formation was lower in low‐latitude species than in high‐latitude species. This interspecific variation is analogous to the intraspecific variation in T. officinale. Time to bud appearance of five populations in T. albidum was homogeneous within and between the populations. The results suggest that the five populations are monoclonal and lack the sensitivity of suppression of flower‐bud formation to high temperature. 相似文献