全文获取类型
收费全文 | 337篇 |
免费 | 25篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 6篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 5篇 |
2015年 | 6篇 |
2014年 | 14篇 |
2013年 | 14篇 |
2012年 | 26篇 |
2011年 | 23篇 |
2010年 | 19篇 |
2009年 | 20篇 |
2008年 | 20篇 |
2007年 | 18篇 |
2006年 | 19篇 |
2005年 | 27篇 |
2004年 | 19篇 |
2003年 | 21篇 |
2002年 | 21篇 |
2001年 | 5篇 |
2000年 | 1篇 |
1999年 | 6篇 |
1998年 | 10篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1974年 | 1篇 |
排序方式: 共有362条查询结果,搜索用时 515 毫秒
1.
Salas-Prato Milagros Tanguay Jean-Francois Lefebvre Yves Wojciechowicz Don Liem H. Heng Barnes David W. Ouellette Ginette Muller-Eberhard Ursula 《In vitro cellular & developmental biology. Plant》1988,24(5):470-470
In Vitro Cellular &; Developmental Biology - Plant - 相似文献
2.
G. Mattei E. Rambeloarisoa G. Giusti J. F. Rontani J. C. Bertrand 《Applied microbiology and biotechnology》1986,23(3-4):302-304
Summary The crude oil was degraded (80%) in continuous culturing and non sterile conditions by a mixed bacteria community. The fermentation process relies on a step of pre-emulsification of the substrate before it is introduced into the reactor. The emulsification indispensable for degrading crude oil is performed by the mixed bacteria community during its growth on hydrocarbons. On the other hand, the use of an ultrafiltration device allows the obtention of high cell concentrations (7.6 g·l-1) and high degradation rates. 相似文献
3.
The effects of deregulation of NR gene expression on growth and nitrogen metabolism of Nicotiana plumbaginifolia plants 总被引:1,自引:0,他引:1
4.
Stanislas Tomavo Jean-Francois Dubremetz Ralph T. Schwarz 《Biology of the cell / under the auspices of the European Cell Biology Organization》1993,78(3):155-162
In this study we describe the biochemical features of the Toxoplasma gondii tachyzoite surface glycoprotein, gp23, demonstrating that it is attached to the parasite membrane by a glycosyl-phosphatidyl inositol anchor. Gp23 was metabolically labeled with tritiated palmitate, myristate, ethanolamine, inositol, glucosamine, mannose and galactose, as expected for a GPI-anchor structure. Gp23 was released from the surface of living parasites after treatment with phosphatidyl inositol-specific phospholipase C (PI-PLC) and the resulting water-soluble protein was immunoprecipitated with a monoclonal antibody specific for gp23. The GPIcore glycan was generated after aqueous-HF dephosphorylation followed by nitrous acid deamination and its carbohydrate structure was analyzed using selective exo- and endoglycosidase treatments. Finally, the phosphatidylinositol moiety of gp23 was characterized using PI-PLC and phospholipase A2 (PLA2) digestions. Our cumulative data suggest that gp23 of T gondii tachyzoites contains a modified GPI-backbone similar to the mammalian Thy-1 anchor, consisting of a conserved core structure (ethanolaminePO4-6-Manαl-2-Manαl-6-Manαl-4-GIcNαl-6-PI) bearing β-linked N-acetylgalactosamine residue(s). 相似文献
5.
6.
Francesco Addabbo Qiuying Chen Dhara P. Patel May Rabadi Brian Ratliff Frank Zhang Jean-Francois Jasmin Michael Wolin Michael Lisanti Steven S. Gross Michael S. Goligorsky 《PloS one》2013,8(6)
Endothelial Cell Dysfunction (ECD) is a recognized harbinger of a host of chronic cardiovascular diseases. Using a mouse model of ECD triggered by treatment with L-Nω-methylarginine (L-NMMA), we previously demonstrated that renal microvasculature displays a perturbed protein profile, including diminished expression of two key enzymes of the Krebs cycle associated with a Warburg-type suppression of mitochondrial metabolism. We hypothesized that supplementation with L-glutamine (GLN), that can enter the Krebs cycle downstream this enzymatic bottleneck, would normalize vascular function and alleviate mitochondrial dysfunction. To test this hypothesis, mice with chronic L-NMMA-induced ECD were co-treated with GLN at different concentrations for 2 months. Results confirmed that L-NMMA led to a defect in acetylcholine-induced relaxation of aortic rings that was dose-dependently prevented by GLN. In caveolin-1 transgenic mice characterized by eNOS inactivation, L-NMMA further impaired vasorelaxation which was partially rescued by GLN co-treatment. Pro-inflammatory profile induced by L-NMMA was blunted in mice co-treated with GLN. Using an LC/MS platform for metabolite profiling, we sought to identify metabolic perturbations associated with ECD and offset by GLN supplementation. 3453 plasma molecules could be detected with 100% frequency in mice from at least one treatment group. Among these, 37 were found to be differentially expressed in a 4-way comparison of control vs. LNMMA both with and without GLN. One of such molecules, hippuric acid, an “uremic toxin” was found to be elevated in our non-uremic mice receiving L-NMMA, but normalized by treatment with GLN. Ex vivo analysis of hippuric acid effects on vasomotion demonstrated that it significantly reduced acetylcholine-induced vasorelaxation of vascular rings. In conclusion, functional and metabolic profiling of animals with early ECD revealed macrovasculopathy and that supplementation GLN is capable of improving vascular function. Metabolomic analyses reveal elevation of hippuric acid, which may further exacerbate vasculopathy even before the development of uremia. 相似文献
7.
Disruption of the mouse mTOR gene leads to early postimplantation lethality and prohibits embryonic stem cell development 总被引:10,自引:0,他引:10 下载免费PDF全文
Gangloff YG Mueller M Dann SG Svoboda P Sticker M Spetz JF Um SH Brown EJ Cereghini S Thomas G Kozma SC 《Molecular and cellular biology》2004,24(21):9508-9516
The mammalian target of rapamycin (mTOR) is a key component of a signaling pathway which integrates inputs from nutrients and growth factors to regulate cell growth. Recent studies demonstrated that mice harboring an ethylnitrosourea-induced mutation in the gene encoding mTOR die at embryonic day 12.5 (E12.5). However, others have shown that the treatment of E4.5 blastocysts with rapamycin blocks trophoblast outgrowth, suggesting that the absence of mTOR should lead to embryonic lethality at an earlier stage. To resolve this discrepancy, we set out to disrupt the mTOR gene and analyze the outcome in both heterozygous and homozygous settings. Heterozygous mTOR (mTOR(+/-)) mice do not display any overt phenotype, although mouse embryonic fibroblasts derived from these mice show a 50% reduction in mTOR protein levels and phosphorylation of S6 kinase 1 T389, a site whose phosphorylation is directly mediated by mTOR. However, S6 phosphorylation, raptor levels, cell size, and cell cycle transit times are not diminished in these cells. In contrast to the situation in mTOR(+/-) mice, embryonic development of homozygous mTOR(-/-) mice appears to be arrested at E5.5; such embryos are severely runted and display an aberrant developmental phenotype. The ability of these embryos to implant corresponds to a limited level of trophoblast outgrowth in vitro, reflecting a maternal mRNA contribution, which has been shown to persist during preimplantation development. Moreover, mTOR(-/-) embryos display a lesion in inner cell mass proliferation, consistent with the inability to establish embryonic stem cells from mTOR(-/-) embryos. 相似文献
8.
Stereospecific synthesis of "para-hydroxymexiletine" and sodium channel blocking activity evaluation
Catalano A Carocci A Fracchiolla G Franchini C Lentini G Tortorella V De Luca A De Bellis M Desaphy JF Conte Camerino D 《Chirality》2004,16(2):72-78
Both enantiomers of "para-hydroxymexiletine" (PHM), one of the main metabolites of mexiletine, were synthesized and fully characterized. Properties of (R)- and (S)-PHM, in terms of blocking potency and stereoselectivity on frog skeletal muscle Na(+) channels, were evaluated. The presence of a hydroxy group on the aryloxy moiety in the 4-position, as in PHM, reduced potency with respect to mexiletine in reducing I(Na max). However, PHM showed clear use-dependent behavior similar to that of mexiletine and, in contrast with what is observed with the parent compound, maintained its stereoselectivity during the use-dependent block. Chirality 16:72-78, 2004. 相似文献
9.
10.
The present study was performed to investigate the effect of previous fasting and lifting of the abdomen of the ewes during transrectal ultrasonographic scanning on the results of early pregnancy diagnosis. Ewes of four flocks (A, B, C and D; all Awassi x Merino ewes, n = 1247 ) aged 0.7-10 years were used in this study. These ewes were estrus synchronized and artificially inseminated. From 2 weeks later onwards, fertile rams were kept with the ewes of flocks A, B and C ( n=949 ) for natural breeding, while ewes of flock D ( n=298 ) were re-inseminated 17 days later. Transrectal ultrasonography (5 MHz) was carried out in ewes of flocks A, B and C on four separate occasions but only once in ewes of flock D. For final analysis, animals were divided over two groups: ewes of Group 1 ( n=949 scans) were scanned in a standing position within the milking parlor. Animals of Group 2 ( n=764 scans) were scanned by the same operator and with the same scanning technique, but these ewes were fasted for 12h prior to scanning and the abdominal wall was lifted, just in front of the udder during scanning. The sensitivity of the test for diagnosing pregnancy at Days 18-24, 25-30, 31-40 and 41-50 was 21.8, 32.3, 63.3 and 50% in Group 1, and 46, 92.5, 92.3 and 96.8% in Group 2, respectively. Only within Group 1, the sensitivity of the test was higher in young ewes (0.7-2 years) than in older ones (>2-10 years). Significant differences were observed at scan periods Days 18-24 and Days 41-50 of gestation. It is concluded that, fasting prior to scanning and lifting the abdomen during scanning significantly improve the accuracy of transrectal ultrasonographic pregnancy diagnosis in Awassi x Merino ewes. 相似文献