全文获取类型
收费全文 | 465篇 |
免费 | 41篇 |
国内免费 | 1篇 |
专业分类
507篇 |
出版年
2023年 | 4篇 |
2022年 | 5篇 |
2021年 | 19篇 |
2020年 | 7篇 |
2019年 | 7篇 |
2018年 | 12篇 |
2017年 | 9篇 |
2016年 | 11篇 |
2015年 | 21篇 |
2014年 | 28篇 |
2013年 | 29篇 |
2012年 | 39篇 |
2011年 | 39篇 |
2010年 | 22篇 |
2009年 | 19篇 |
2008年 | 26篇 |
2007年 | 22篇 |
2006年 | 12篇 |
2005年 | 15篇 |
2004年 | 15篇 |
2003年 | 16篇 |
2002年 | 15篇 |
2001年 | 3篇 |
2000年 | 7篇 |
1999年 | 7篇 |
1998年 | 6篇 |
1997年 | 8篇 |
1996年 | 6篇 |
1995年 | 7篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 8篇 |
1988年 | 3篇 |
1986年 | 7篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1979年 | 2篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1970年 | 1篇 |
1968年 | 2篇 |
1966年 | 1篇 |
1957年 | 1篇 |
1943年 | 1篇 |
排序方式: 共有507条查询结果,搜索用时 0 毫秒
71.
Aina Solà Hannu Maaheimo Katri Yl?nen Pau Ferrer Thomas Szyperski 《European journal of biochemistry》2004,271(12):2462-2470
Amino acid biosynthesis and central carbon metabolism of Pichia pastoris were studied using biosynthetically directed fractional (13)C labeling. Cells were grown aerobically in a chemostat culture fed at two dilution rates (0.05 h(-1), 0.16 h(-1)) with glycerol as the sole carbon source. For investigation of amino acid biosynthesis and comparison with glycerol cultivations, cells were also grown at 0.16 h(-1) on glucose. Our results show that, firstly, amino acids are synthesized as in Saccharomyces cerevisiae. Secondly, biosynthesis of mitochondrial pyruvate via the malic enzyme is not registered for any of the three cultivations. Thirdly, transfer of oxaloacetate across the mitochondrial membrane appears bidirectional, with a smaller fraction of cytosolic oxaloacetate stemming from the mitochondrial pool at the higher dilution rate of 0.16 h(-1) (for glucose or glycerol cultivation) when compared to the glycerol cultivation at 0.05 h(-1). Fourthly, the fraction of anaplerotic synthesis of oxaloacetate increases from 33% to 48% when increasing the dilution rate for glycerol supply, while 38% is detected when glucose is fed. Finally, the cultivation on glucose also allowed qualitative comparison with the flux ratio profile previously published for Pichia stipitis and S. cerevisiae grown on glucose in a chemostat culture at a dilution rate of 0.1 h(-1). This provided a first indication that regulation of central carbon metabolism in P. pastoris and S. cerevisiae might be more similar to each other than to P. stipitis. 相似文献
72.
73.
74.
75.
Recombinant Candida rugosa LIP2 expression in Pichia pastoris under the control of the AOX1 promoter
Pau Ferrer Manuel Alarcn Ramn Ramn María Dolors Benaiges Francisco Valero 《Biochemical Engineering Journal》2009,46(3):271-277
The LIP2 isoenzyme gene from Candida rugosa has been completely synthesised and functionally expressed under the AOX1 promoter control in Pichia pastoris. The on-line monitoring and control of methanol, the key inducer carbon source in fed-batch cultures, has enhanced the yield product/biomass 7.8-fold and the productivity 12.8-fold compared to the best batch cultivation with the Pichia system and, 10-fold compared to the fed-batch cultivation process using the native C. rugosa strain.Nevertheless, the high ionic strength of culture broth favoured aggregation of Lip2, leading to total loss of lipolytic activity. After cultivation, a diaultrafiltration process was implemented to diminish ionic strength, allowing for the recovery of lipolytic activity in the diaultrafiltrate. The developed bioprocess resulted into a reproducible product in terms of quality and productivity. 相似文献
76.
Benaiges MD Alarcón M Fuciños P Ferrer P Rua M Valero F 《Biotechnology progress》2010,26(5):1252-1258
The characterization of the recombinant Candida rugosa Lip2 (r-Lip2) isoenzyme obtained from fed-batch cultures of Pichia pastoris under PAOX promoter was carried out, determining the optimal pH and temperature as well as their catalytic performance in both hydrolysis and synthesis reactions comparing with purified native Lip2 (n-Lip2) previously determined. The substrate specificity of r-Lip2 in hydrolysis reactions was determined with a series of triacylglycerols and p-nitrophenyl esters of variable acyl chain length. r-Lip2 showed the maximum specificity for both substrates towards medium-chain esters (C-8), similar behavior was observed with n-Lip2. However, significant differences were observed towards unsaturated substrates (triolein) or short-chain esters. A statistical design applied to study the effect of pH and temperature on lipase stability shown that r-Lip2, like n-Lip2, was more sensitive to pH than temperature changes. Nevertheless, the overall stability of soluble r-Lip2 was lower than soluble n-Lip2. The stability of r-lip2 was significantly improved by immobilization onto EP100, an excellent support for lipases with yields around 95% for offered lipolytic activity lower than 600 AU/mL. Finally, immobilized r-Lip2 was tested in the resolution of ibuprofen in isooctane by means of enantioselective esterification using 1-butanol as esterifying agent. r-Lip2 showed a better performance in terms of enantiomeric excess (74%) and enatiomeric factor (96%) than n-Lip2 (56 and 80%, respectively) for the same conversion (40%). Thus, r-Lip2 should be considered a good and pure biocatalyst, easy to produce and with a remaining activity of ca. 90% after one reaction cycle when immobilized on EP100. 相似文献
77.
Víctor Vinuesa Joan Madurell-Malapeira Lars Werdelin Josep M. Robles Pau Obradó David M. Alba 《Journal of Mammalian Evolution》2017,24(2):207-219
The European Miocene records a wide diversity of hyaenid ecomorphotypes represented by multiple genera. Among these, Hyaenictis Gaudry, 1861, is one of the least known. This genus includes four species from the late Miocene and Pliocene of the Old World, but in Europe Hyaenictis is only represented by two species, recorded by scarce and fragmentary remains: Hyaenictis graeca Gaudry, 1861, from Pikermi (MN12; Greece) and Hyaenictis almerai Villalta Comella and Crusafont Pairó, 1948, from Sant Miquel de Toudell (MN10; Vallès-Penedès Basin, NE Iberia). Here, we describe a new skull of Hyaenictis aff. almerai from the Vallès-Penedès site of Ronda Oest Sabadell Sector D (MN10), representing the most complete European specimen of the genus. In the presence of m2 and virtual lack of m1 metaconid, the described cranium more closely resembles Hyaenictis rather than any other medium- to large-sized European hyaenid. However, the new skull does not fit well with previously known Hyaenictis species, more closely resembling the bone-cracking Adcrocuta Kretzoi, 1938, in the development of premolar accessory cuspids and the possession of relatively broad cheek teeth. These and other features (strong mandibular muscular insertions and enamel microstructure) denote more durophagous adaptations than previously documented in Hyaenictis (considered a cursorial/dog-like hyaena), and favor the inclusion of H. aff. almerai in the transitional bone-cracking hyaenid ecomorphotype. 相似文献
78.
79.
80.
Oswaldo Lorenzo-Betancor Kotaro Ogaki Alexandra Soto-Ortolaza Catherine Labbé Carles Vilari?o-Güell Alex Rajput Ali H. Rajput Pau Pastor Sara Ortega Elena Lorenzo Audrey J. Strongosky Jay A. van Gerpen Ryan J. Uitti Zbigniew K. Wszolek Owen A. Ross 《PloS one》2014,9(11)