全文获取类型
收费全文 | 844篇 |
免费 | 64篇 |
出版年
2023年 | 6篇 |
2022年 | 13篇 |
2021年 | 29篇 |
2020年 | 19篇 |
2019年 | 15篇 |
2018年 | 17篇 |
2017年 | 12篇 |
2016年 | 31篇 |
2015年 | 52篇 |
2014年 | 53篇 |
2013年 | 73篇 |
2012年 | 69篇 |
2011年 | 90篇 |
2010年 | 53篇 |
2009年 | 40篇 |
2008年 | 45篇 |
2007年 | 43篇 |
2006年 | 50篇 |
2005年 | 33篇 |
2004年 | 43篇 |
2003年 | 36篇 |
2002年 | 33篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 7篇 |
1997年 | 4篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1980年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有908条查询结果,搜索用时 31 毫秒
1.
Virulence of 10 human and 10 bovine isolates (5 type II and 5 type III of each origin) of group B streptococci (GBS) was measured in two experimental mouse models. In the first model, mice were intraperitoneally (i.p.) infected, and the 50% lethal doses (LD50) were significantly lower for human isolates than for bovine isolates. In the second model, abortion and lethality were recorded for mice infected intravenously (i.v.) on day 13 of pregnancy. All 10 human isolates induced abortions, whereas only 5 bovine isolates did so. There was no relationship between 50% abortive doses determined for 9 isolates (4 human and 5 bovine) and the LD50 values. Post-partum lethality was significantly correlated with LD50 values.Our studies suggested that the lethality test for nonpregnant mice and the abortion test for pregnant mice were not redundant and that the latter would be a useful additional model for identification of virulence factors of GBS. 相似文献
2.
3.
Sylvie Leparoux Marc Padrines Yannick Fortun Bernard Colas 《Biotechnology letters》1996,18(2):135-138
Summary Enzymatic O-glycosylation of dipeptide derivatives containing a serine residue in the N or C terminal position and alanine or glycine as the second amino acid was achieved using the transgalactosylation activity of -galactosidase from the Achatina achatina digestive juice. Reactions were performed with lactose as glycosyl donor and the dipeptide ethyl (or methyl) esters N-protected by a benzyloxycarbonyl group (Z) as glycosyl acceptors. Yields of galactosyl-dipeptide derivatives were much higher than those obtained with the E.coli -galactosidase as catalyst. 相似文献
4.
Yves Paquette Yannick Merlen Brigitte Malette Gilles Bleau 《Molecular reproduction and development》1995,42(4):388-396
Oviductins are high-molecular-weight glycoproteins specifically secreted by the oviduct. These proteins bind to the zona pellucida of the ovulated oocyte and remain associated with the embryo during its transit in the oviduct. They may be involved in fertilization and early embryonic development. In order to explore their putative biological function, the cDNA sequence corresponding to oviductin in the golden hamster was determined. We found that the deduced amino acid sequence of this heavily O-glycosylated protein presents characteristics typical of mucins, including serine- or threonine-rich tandem repeats. Analysis of several cDNA clones and of genomic DNA revealed the presence of a single copy gene with two frequent alleles differing in the number of repeats. Comparison with oviductin sequences from other mammals indicates a high degree of conservation amongst species, except for the repeat region which shows divergence, notably in the number of repeats. Based on its biochemical and genetic properties, hamster oviductin can now be classified as a secretory mucin. This concept provides a new insight in the elucidation of its biological role: oviductin could possibly provide the oviduct and the oocyte with a protective coating ensuring normal tubal function and embryonic development. © 1995 wiley-Liss, Inc. 相似文献
5.
Yannick Azou Monique Laval 《Biology of the cell / under the auspices of the European Cell Biology Organization》1993,77(2):155-164
Summary— We have previously shown the presence, in the amplified DNA of a Drosophila cell line resistant to N-phosphonacetyl-L-aspartate (PALA), of two units of 150 kb and 120 kb respectively duplicated and amplified. The two joints (J1 and J2) linking these units as well as their respective wild-type counterparts have been sequenced. Sequence analysis indicates that a region of the Drosophila genome which corresponds to the proximal boundary of the 150 kb unit is common to both joints. In addition to this common region, the J1 junction possesses a 26-nucleotide sequence belonging to the J2 junction. This indicates that the J2 junction was the first formed, and that J1, therefore, results from recombination between J2 and a region of the wild-type genome 120 kb distal to J2. Sequence analysis also reveals that the joints result from illegitimate recombination between unrelated regions. AT-rich sequences, strand bias composition and putative topoisomerase I and II sites were found in at least one of the two parental sequences involved in the formation of the joints. On the basis of these results we can hypothesize that after two illegitimate recombinations between sister chromatids, leading first to J2 and then to J1, the amplification may have arisen by a series of homologous (unequal crossing-over) or illegitimate recombinations, or by an intrachromosomal rolling circle. 相似文献
6.
Monospecific polyclonal antibodies directed against purified cinnamate 4-hydroxylase from Helianthus tuberosus. Immunopurification, immunoquantitation, and interspecies cross-reactivity. 总被引:5,自引:5,他引:0 下载免费PDF全文
We recently reported the purification of cinnamic acid 4-hydroxylase (CA4H), a cytochrome P-450 catalyzing the second reaction of the general phenylpropanoid pathway, from Jerusalem artichoke (Helianthus tuberosus L.) (B. Gabriac, D. Werck-Reichhart, H. Teutsch, F. Durst [1991] Arch Biochem Biophys 288: 302-309). Rabbit polyclonal antibodies were raised against the native and denaturated nitrocellulose-bound enzyme. Only the immunoglobulins G (IgGs) elicited upon immunization with native enzyme produced strong inhibition of catalytic activity and good cross-reactivity on western blots. In microsomes from H. tuberosus tissues induced by wounding and various chemicals, a positive correlation between catalytic activity and amounts of immunoreactive protein on western blots was observed. When coupled to cyanogen bromide-activated Sepharose, purified IgGs selectively retained CA4H activity from solubilized plant microsomes. Acid elution from the immunoaffinity matrix provided a rapid procedure for high-yield purification of the CA4H protein. The same IgGs immunoprecipitated a single protein from the in vitro translation products of mRNA isolated from wounded tissues. The apparent molecular weight (57,000) of this polypeptide was identical to that of CA4H purified from tuber microsomes. Immunochemical relatedness between CA4H from different plant species was demonstrated by strong inhibition of catalytic activity and immunopurification of several orthologous enzymes, using IgGs directed against CA4H from H. tuberosus. However, only limited interspecies cross-reactivity was observed on western blots. A careful immunochemical analysis indicates that CA4H immunoreactivity significantly differs from plant to plant. Results are discussed in terms of antibody specificity, enzyme glycosylation, and CA4H regulation. 相似文献
7.
8.
9.
Carrière Audrey Lagarde Damien Jeanson Yannick Portais Jean-Charles Galinier Anne Ader Isabelle Casteilla Louis 《Journal of physiology and biochemistry》2020,76(2):241-250
Journal of Physiology and Biochemistry - Thermogenic (brown and beige) adipose tissues improve glucose and lipid homeostasis and therefore represent putative targets to cure obesity and related... 相似文献
10.
Plant and Soil - Land cover change (LCC) from natural forest (NF) to plantations (PF) has occurred worldwide over the past several decades. However, the different LCC effects on soil aggregate C... 相似文献