全文获取类型
收费全文 | 789篇 |
免费 | 37篇 |
出版年
2022年 | 5篇 |
2021年 | 8篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 6篇 |
2017年 | 11篇 |
2016年 | 15篇 |
2015年 | 29篇 |
2014年 | 30篇 |
2013年 | 54篇 |
2012年 | 38篇 |
2011年 | 51篇 |
2010年 | 16篇 |
2009年 | 27篇 |
2008年 | 50篇 |
2007年 | 53篇 |
2006年 | 52篇 |
2005年 | 53篇 |
2004年 | 55篇 |
2003年 | 39篇 |
2002年 | 27篇 |
2001年 | 7篇 |
2000年 | 8篇 |
1999年 | 7篇 |
1998年 | 10篇 |
1997年 | 11篇 |
1996年 | 4篇 |
1995年 | 9篇 |
1994年 | 6篇 |
1993年 | 6篇 |
1992年 | 10篇 |
1991年 | 12篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1988年 | 12篇 |
1987年 | 6篇 |
1986年 | 9篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1980年 | 9篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 5篇 |
1974年 | 6篇 |
1973年 | 2篇 |
1970年 | 3篇 |
1966年 | 3篇 |
排序方式: 共有826条查询结果,搜索用时 630 毫秒
31.
Noboru Katayama David H. Hembry Masaru K. Hojo Nobuhiko Suzuki 《Ecological Research》2013,28(5):919-926
When aphids parasitize plants with extrafloral nectaries (EFNs) and aphid colony size is small, ants frequently use EFNs but hardly tend aphids. However, as the aphid colony size increases, ants stop using EFNs and strengthen their associations with aphids. Although the shift in ant behavior is important for determining the dynamics of the ant–plant–aphid interaction, it is not known why this shift occurs. Here, we test two hypotheses to explain the mechanism responsible for this behavioral shift: (1) Extrafloral nectar secretion changes in response to aphid herbivory, or (2) plants do not change extrafloral nectar secretion, but the total reward to ants from aphids will exceed that from EFNs above a certain aphid colony size. To judge which mechanism is plausible, we investigated secretion patterns of extrafloral nectar produced by plants with and without aphids, compared the amount of sugar supplied by EFNs and aphids, and examined whether extrafloral nectar or honeydew was more attractive to ants. Our results show that there was no inducible extrafloral secretion in response to aphid herbivory, but the sugar concentration in extrafloral nectar was higher than in honeydew, and more ant workers were attracted to an artificial extrafloral nectar solution than to an artificial aphid honeydew solution. These results indicate that extrafloral nectar is a more attractive reward than aphid honeydew per unit volume. However, even an aphid colony containing only two individuals can supply a greater reward to ants than EFNs. This suggests that the ant behavioral shift may be explained by the second hypothesis. 相似文献
32.
Kazuaki Manabe Mitsuyoshi Morii Masaru Honjo Masaharu Ohoka Kouichiro Fushimi Akiko Sawakura 《Bioscience, biotechnology, and biochemistry》2013,77(8):2261-2267
Bacillus subtilis 1A20 transformed with a hybrid plasmid, pNP150, to which a DNA fragment from Bacillus amyloliquefaciens F was attached, produced a large amount of a neutral protease. To identify the origin of the gene specifying this neutral protease, neutral proteases from B. amyloliquefaciens F, B. subtilis NP58 (a derivative of Marburg 6160), and B. subtilis 1A20 transformed with pNP150 were purified. We investigated their immunological properties and primary structures.The proteases from these two species were indistinguishable by chromatography, but they were distinguishable from each other by SDS-polyacrylamide gel electrophoresis and double immunodiffusion. Amino acid sequencing of these two proteases by Edman degradation showed that there were four substitutions in the 20-residue amino acid sequence from the N-termini.Neutral protease from the transformant had the same immunological characteristics and N-terminal amino acid sequence as that from B. amyloliquefaciens. These results meant that the gene in question was derived from a gene specifying the neutral protease in this bacterium. 相似文献
33.
Ichizo Shinoda Akira Fushimi Hironobu Kato Hideo Okai Sakuzo Fukui 《Bioscience, biotechnology, and biochemistry》2013,77(9):2587-2596
The primary structure of bovine β-casein contains the partial sequence of -Pro196-Val-Leu-Gly-Pro-Val-Arg-Gly-Pro-Phe-Pro-Ile-Ile-Val209 in the C-terminal portion. We previously reported that the synthetic C-terminal octapeptide, Arg202-Val209, is extremely bitter with its threshold value 0.004 mm, 250 times as strong as that of caffeine. To further investigate the bitter taste of the C-terminal portion of β-casein, we synthesized the C-terminal tetradecapeptide, Pro196-Val209, and some of its fragments. A hydrophobic hexapeptide, Pro196-Val201, was twice as bitter as caffeine. The bitter taste of the decapeptide, Pro200-Val209, was the same as that of Arg202-Val209. Although the tetradecapeptide, Pro196-Val209, was composed of two bitter peptides, Pro196-Val201 and Arg202-Val209, its bitter taste was weaker than that of Arg202-Val209 and its threshold value was 0.015 mm. We suggested that the increase of bitterness in peptides through the introduction of hydrophobic amino acids depended on the number of hydrophobic amino acids added. In addition, the synthetic retro analog of Arg202-Val209 (H-Val-Ile-Ile-Pro-Phe-Pro-Gly-Arg-OH) was not as bitter as Arg202-Val209. This indicated that the sequence of Arg202-Val209 is important for extreme bitterness. 相似文献
34.
Hitomi Yatsuki Ken Higashimoto Kosuke Jozaki Kayoko Koide Junichiro Okada Yoriko Watanabe Nobuhiko Okamoto Yoshinobu Tsuno Yoko Yoshida Kazutoshi Ueda Kenji Shimizu Hirofumi Ohashi Tsunehiro Mukai Hidenobu Soejima 《Genes & genomics.》2013,35(2):141-147
Beckwith-Wiedemann syndrome (BWS) is an imprinting-related human disease that is characterized by macrosomia, macroglossia, abdominal wall defects, and variable minor features. BWS is caused by several genetic/epigenetic alterations, such as loss of methylation at KvDMR1, gain of methylation at H19-DMR, paternal uniparental disomy of chromosome 11, CDKN1C mutations, and structural abnormalities of chromosome 11. CDKN1C is an imprinted gene with maternal preferential expression, encoding for a cyclin-dependent kinase (CDK) inhibitor. Mutations in CDKN1C are found in 40 % of familial BWS cases with dominant maternal transmission and in ~5 % of sporadic cases. In this study, we searched for CDKN1C mutations in 37 BWS cases that had no evidence for other alterations. We found five mutations—four novel and one known—from a total of six patients. Four were maternally inherited and one was a de novo mutation. Two frame-shift mutations and one nonsense mutation abolished the QT domain, containing a PCNA-binding domain and a nuclear localization signal. Two missense mutations occurred in the CDK inhibitory domain, diminishing its inhibitory function. The above-mentioned mutations were predicted by in silico analysis to lead to loss of function; therefore, we strongly suspect that such anomalies are causative in the etiology of BWS. 相似文献
35.
Conserved roles of fibroblast growth factor receptor 2 signaling in the regulation of inner cell mass development in bovine blastocysts
下载免费PDF全文
![点击此处可从《Molecular reproduction and development》网站下载免费的PDF全文](/ch/ext_images/free.gif)
36.
Takano Y Yamauchi K Hayakawa K Hiramatsu N Kasai A Okamura M Yokouchi M Shitamura A Yao J Kitamura M 《FEBS letters》2007,581(3):421-426
Expression of nephrin, a crucial component of the glomerular slit diaphragm, is downregulated in patients with proteinuric glomerular diseases. Using conditionally immortalized reporter podocytes, we found that bystander macrophages as well as macrophage-derived cytokines IL-1beta and TNF-alpha markedly suppressed activity of the nephrin gene promoter in podocytes. The cytokine-initiated repression was reversible, observed on both basal and inducible expression, independent of Wilms' tumor suppressor WT1, and caused in part via activation of the phosphatidylinositol-3-kinase/Akt pathway. These results indicated a novel mechanism by which activated macrophages participate in the induction of proteinuria in glomerular diseases. 相似文献
37.
Rapid, transient induction of ER stress in the liver and kidney after acute exposure to heavy metal: evidence from transgenic sensor mice 总被引:2,自引:0,他引:2
Hiramatsu N Kasai A Du S Takeda M Hayakawa K Okamura M Yao J Kitamura M 《FEBS letters》2007,581(10):2055-2059
Endoplasmic reticulum (ER) stress-responsive alkaline phosphatase (ES-TRAP) serves as a sensitive indicator for ER stress. In response to heavy metals including cadmium, nickel and cobalt, hepatocytes and renal tubular cells expressing ES-TRAP exhibited ER stress and decreased ES-TRAP activity. In ES-TRAP transgenic mice, acute exposure to cadmium showed rapid, transient decreases in the activity of serum ES-TRAP. It was inversely correlated with the induction of endogenous ER stress markers in the liver and kidney. Our result provides first evidence for the acute, reversible induction of ER stress in vivo after exposure to heavy metal. 相似文献
38.
Uemoto Y Suzuki S Terada N Ohno N Ohno S Yamanaka S Komada M 《The Journal of biological chemistry》2007,282(9):6548-6555
At axon initial segments and nodes of Ranvier in neurons, the spectrin membrane skeleton plays roles in physically stabilizing the plasma membrane integrity and in clustering voltage-gated sodium channels for proper conduction of the action potential. betaIV-Spectrin, an essential component of the membrane skeleton at these sites, has an N-terminal-truncated isoform, Sigma6, which is expressed at much higher levels than the full-length isoform Sigma1. To investigate the role of betaIV-spectrin Sigma6, we generated Sigma1-deficient mice with a normal level of Sigma6 expression (Sigma1(-/-) mice), and compared their phenotypes with those of previously generated mice lacking both Sigma1 and Sigma6(Sigma1Sigma6(-/-) mice). The gross neurological defects observed in Sigma1Sigma6(-/-) mice, such as hindleg contraction, were apparently ameliorated in Sigma1(-/-) mice. At cellular levels, Sigma1Sigma6(-/-) and Sigma1(-/-) neurons similarly exhibited waving and swelling of the plasma membrane at axon initial segments and nodes of Ranvier. By contrast, the levels of ankyrin G and voltage-gated sodium channels at these sites, which are significantly reduced in Sigma1Sigma6(-/-) mice, were substantially recovered in Sigma1(-/-) mice. We conclude that the truncated betaIV-spectrin isoform Sigma6 plays a specific role in clustering voltage-gated sodium channels, whereas it is dispensable for membrane stabilization at axon initial segments and nodes of Ranvier. 相似文献
39.
Effects of soybean beta-conglycinin on hepatic lipid metabolism and fecal lipid excretion in normal adult rats 总被引:1,自引:0,他引:1
Fukui K Kojima M Tachibana N Kohno M Takamatsu K Hirotsuka M Kito M 《Bioscience, biotechnology, and biochemistry》2004,68(5):1153-1155
beta-Conglycinin decreased blood triacylglycerol (TAG) levels in male Wistar adult rats. Liver mitochondrial carnitine palmitoyltransferase activity in the beta-conglycinin-fed group significantly increased as against the casein-fed group. Hepatic fatty acid synthase activity in the beta-conglycinin group significantly decreased as against that of the casein-fed group. Fecal fatty acid excretion in the beta-conglycinin group was significantly higher than in the casein group. 相似文献
40.
Zoppellaro G Sakurai N Kataoka K Sakurai T 《Bioscience, biotechnology, and biochemistry》2004,68(9):1998-2000
The redox state of type I Cu in Myrothecium verrucaria bilirubin oxidase (BO), a multicopper oxidase utilized in the clinical investigation of liver, is an equilibrium state of the oxidized and reduced forms, reflected in the reversible absorption and electron paramagnetic resonance (EPR) spectral changes depending on pH. 相似文献