全文获取类型
收费全文 | 209篇 |
免费 | 15篇 |
出版年
2022年 | 2篇 |
2021年 | 5篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2017年 | 2篇 |
2016年 | 5篇 |
2015年 | 8篇 |
2014年 | 13篇 |
2013年 | 12篇 |
2012年 | 17篇 |
2011年 | 10篇 |
2010年 | 6篇 |
2009年 | 16篇 |
2008年 | 14篇 |
2007年 | 10篇 |
2006年 | 10篇 |
2005年 | 11篇 |
2004年 | 15篇 |
2003年 | 11篇 |
2002年 | 8篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 3篇 |
1971年 | 2篇 |
1970年 | 1篇 |
1969年 | 2篇 |
排序方式: 共有224条查询结果,搜索用时 31 毫秒
21.
Fierens K Geudens N Brijs K Courtin CM Gebruers K Robben J Van Campenhout S Volckaert G Delcour JA 《Protein expression and purification》2004,37(1):39-46
Triticum aestivum xylanase inhibitor I (TAXI-I) is a wheat protein that inhibits microbial xylanases belonging to glycoside hydrolase family 11. In the present study, recombinant TAXI-I (rTAXI-I) was successfully produced by the methylotrophic yeast Pichia pastoris at high expression levels (approximately 75 mg/L). The rTAXI-I protein was purified from the P. pastoris culture medium using cation exchange and gel filtration chromatographic steps. rTAXI-I has an iso-electric point of at least 9.3 and a mass spectrometry molecular mass of 42,013 Da indicative of one N-linked glycosylation. The recombinant protein fold was confirmed by circular dichroism spectroscopy. Xylanase inhibition by rTAXI-I was optimal at 20-30 degrees C and at pH 5.0. rTAXI-I still showed xylanase inhibition activity at 30 degrees C after a 40 min pre-incubation step at temperatures between 4 and 70 degrees C and after 2 h pre-incubation at room temperature at a pH ranging from 3.0 to 12.0, respectively. All tested glycoside hydrolase family 11 xylanases were inhibited by rTAXI-I whereas those belonging to family 10 were not. Specific inhibition activities against family 11 Aspergillus niger and Bacillus subtilis xylanases were 3570 and 2940IU/mg protein, respectively. The obtained biochemical characteristics of rTAXI-I produced by P. pastoris (no proteolytical cleft) were similar to those of natural TAXI-I (mixture of proteolytically processed and non-processed forms) and non-glycosylated rTAXI-I expressed in Escherichia coli. The present results show that xylanase inhibition activity of TAXI-I is only affected to a limited degree by its glycosylation or proteolytic processing. 相似文献
22.
De Haes P Garmyn M Degreef H Vantieghem K Bouillon R Segaert S 《Journal of cellular biochemistry》2003,89(4):663-673
We investigated the capacity of 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] to protect human keratinocytes against the hazardous effects of ultraviolet B (UVB)-irradiation, recognized as the most important etiological factor in the development of skin cancer. Cytoprotective effects of 1,25(OH)(2)D(3) on UVB-irradiated keratinocytes were seen morphologically and quantified using a colorimetric survival assay. Moreover, 1,25(OH)(2)D(3) suppressed UVB-induced apoptotic cell death. An ELISA, detecting DNA-fragmentation, demonstrated that pretreatment of keratinocytes with 1,25(OH)(2)D(3) 1 microM for 24 h reduced UVB-stimulated apoptosis by 55-70%. This suppression required pharmacological concentrations 1,25(OH)(2)D(3) and a preincubation period of several hours. In addition, 1,25(OH)(2)D(3) also inhibited mitochondrial cytochrome c release (90%), a hallmark event of UVB-induced apoptosis. Furthermore, we demonstrated that 1,25(OH)(2)D(3) reduced two important mediators of the UV-response, namely, c-Jun-NH(2)-terminal kinase (JNK) activation and interleukin-6 (IL-6) production. As shown by Western blotting, pretreatment of keratinocytes with 1,25(OH)(2)D(3) 1 microM diminished UVB-stimulated JNK activation with more than 30%. 1,25(OH)(2)D(3) treatment (1 microM) reduced UVB-induced IL-6 mRNA expression and secretion with 75-90%. Taken together, these findings suggest the existence of a photoprotective effect of active vitamin D(3) and create new perspectives for the pharmacological use of active vitamin D compounds in the prevention of UVB-induced skin damage and carcinogenesis. 相似文献
23.
Raes K De Smet S Balcaen A Claeys E Demeyer D 《Reproduction, nutrition, development》2003,43(4):331-345
The present study was aimed at investigating the effect of duration and time of feeding n-3 fatty acids on the fatty acid composition of intramuscular fat and adipose tissue of bulls at slaughter. Four groups of bulls were given during three periods different diets, mainly differing in the presence of linseed as the predominant n-3 fatty acid source in the concentrate either or not in combination with grass (silage) as the roughage. The results show that the fatty acid composition of the feed during the earlier periods of life of the animal were important and influenced the final intramuscular fatty acid composition. Feeding n-3 PUFA during the phases before the finishing diet increased the long chain n-3 PUFA (C20:5n-3, C22:5n-3 and C22:6n-3) compared to animals which were fed only a C 18:3n-3 rich concentrate in the finishing period. The cis-9,trans-11CLA content was increased by feeding linseed in the fattening period and was mainly deposited in the triacylglycerol fraction of the intramuscular fat. 相似文献
24.
In experiments on rats under urethane anesthesia, we studied how microinjections of vasopressin into the spinal trigeminal nucleus influence jaw-opening reflexes (JOR): nociceptive JOR, induced by stimulation of the tooth pulp, and non-nociceptive JOR, evoked by stimulation of A fibers of the infraorbital nerve. It was shown that injection of 10 M vasopressin resulted in a pronounced decrease (by 45-50%) in the nociceptive JOR amplitude for 25-30 min, whereas the non-nociceptive JOR dropped only by 8-10% for 11-13 min. It is concluded that vasopressin predominantly affects the nociceptive JOR; this fact is obviously related to a central analgesic effect of this peptide. 相似文献
25.
Michiel Etienne Janssens Dirk Geysen Katleen Broos Ine De Goeyse Johan Robbens Filip Van Petegem Jean-Pierre Timmermans Yves Guisez 《Amino acids》2010,38(5):1617-1626
The hepatitis B core (HBc) protein has been used successfully in numerous experiments as a carrier for heterologous peptides.
Folding and capsid formation of the chimeric proteins is not always achieved easily. In silico analyses were performed to
provide further comprehension of the feasibility for predicting successful capsid formation. In contrast to previous work,
we show that common in silico predictions do not ensure assembly into particles. We included new considerations regarding
capsid formation of HBc fusion proteins. Not only the primary sequence and the length of the inserts seem important, also
the rigidity, the distance between the N and the C-terminus and the presence of cysteines, which could form disulphide bonds,
could influence proper capsid formation. Furthermore, new conformational insights were formulated when linkers were added
to create extra flexibility of the chimeric particles. Different hypotheses were suggested to clarify the obtained results.
To this extent, the addition of glycine-rich linkers could lower high rigidity of the insert, removal of the strain of the
core protein or ease interaction between the HBc and the insert. Finally, we observed specific changes in capsid formation
properties when longer linkers were used. These findings have not been reported before in this and other virus-like particle
carriers. In this study, we also propose a new high-yield purification protocol for fusion proteins to be used in vaccination
experiments with the carrier protein or in comparative studies of particulate or non-particulate HBc fusion proteins. 相似文献
26.
Katleen Van Steendam Kelly Tilleman Marlies De Ceuleneer Filip De Keyser Dirk Elewaut Dieter Deforce 《Arthritis research & therapy》2010,12(4):R132
Introduction
Rheumatoid arthritis (RA) is an inflammatory disease, which results in destruction of the joint. The presence of immune complexes (IC) in serum and synovial fluid of RA patients might contribute to this articular damage through different mechanisms, such as complement activation. Therefore, identification of the antigens from these IC is important to gain more insight into the pathogenesis of RA. Since RA patients have antibodies against citrullinated proteins (ACPA) in their serum and synovial fluid (SF) and since elevated levels of citrullinated proteins are detected in the joints of RA patients, citrullinated antigens are possibly present in IC from RA patients. 相似文献27.
28.
Caribbean Anolis lizards are often cited as a textbook example of adaptive radiation. Similar morphologies (ecomorphs) have originated in similar ecological settings on different large islands in the West Indies. However, relatively little is known about one of the morphologically most specialized and divergent ecomorphs: the twig anoles. Here, we investigate aspects of morphology, dewlap size, locomotor and bite performance, structural habitat and diet of the poorly known twig anole, Anolis sheplani from Hispaniola. Few observations have previously been made of this species in its natural habitat, and few quantitative data on its natural history are available. A. sheplani is an extreme twig anole with respect to its morphology, performance capacities, and ecological niche. Males and females of this species do not differ from each other in body dimensions, performance or habitat use, but males do have a bigger dewlap than females. We present data for 25 individuals and compare them with data for other Greater Antillean anoles. It becomes apparent that twig anoles constitute a large component of the morphological, functional, and ecological diversity of Anolis lizards. Small twig anoles such as A. sheplani appear to be pushing the boundaries of morphospace and are thus crucial in our understanding of the evolution of phenotypic diversity. 相似文献
29.
Ineke?van?Gremberghe Katleen?Van der?Gucht Pieter?Vanormelingen Tsehaye?Asmelash Tadesse?Dejenie Sofie?D’hondt Steven?Declerck Luc?De?Meester Wim?VyvermanEmail author 《Aquatic Ecology》2011,45(2):289-306
The cyanobacterium Microcystis is notorious for forming extensive and potentially toxic blooms in nutrient-rich freshwater bodies worldwide. However, little
is known about the factors underlying the genetic diversity and structure of natural Microcystis populations, despite the fact that this knowledge is essential to understand the build-up of blooms. Microcystis blooms are common and occur year-round in Africa, but are underinvestigated in this continent. We studied the genetic diversity
and structure of Microcystis populations in 30 man-made reservoirs in Tigray (Northern Ethiopia) using Denaturing Gradient Gel Electrophoresis of the
16S–23S rDNA internal transcribed spacer (ITS) region and assessed the importance of local environmental conditions and geographic
position of the reservoirs for the observed patterns. The analyses showed that both regional and local Microcystis ITS diversity in these recently constructed reservoirs was relatively low, with several dense blooms containing only a single
ITS type. Especially one non-toxic ITS type dominated a considerable fraction of Microcystis blooms, but appeared restricted in its geographic distribution. The relationship between Microcystis ITS population structure and abiotic variables (water clarity, pH) and with zooplankton (Daphnia biomass) indicates a (limited) influence of environmental conditions on Microcystis population structure in the reservoirs of Tigray. 相似文献
30.
Irschick DJ Herrel A Vanhooydonck B Huyghe K Van Damme R 《Evolution; international journal of organic evolution》2005,59(7):1579-1587
A key assumption in evolutionary studies of locomotor adaptation is that standard laboratory measures of performance accurately reflect what animals do under natural circumstances. One widely examined measure of performance is maximum sprint speed, which is believed to be important for eluding predators, capturing prey, and defending territories. Previous studies linking maximum sprint speed to fitness have focused on laboratory measurements, and we suggest that such analyses may be appropriate for some species and intraspecific classes, but not others. We provide evidence for a general inverse relationship between maximum laboratory sprint speed and the percentage of maximum capacity that animals use when escaping from a threat in the field (the model of locomotor compensation). Further, absolute values of field escape speed and maximum laboratory speed are not significantly related when comparing across a diverse group of Anolis and lacertid lizards. We show that this pattern of locomotor compensation holds both within (i.e., among intraspecific classes) and among lizard species (with some exceptions). We propose a simple method of plotting field escape speed (y-axis) versus maximum laboratory speed (x-axis) among species and/or intraspecific classes that allows researchers to determine whether their study organisms are good candidates for relating laboratory performance to fitness. We suggest that species that reside directly on, or near the "best fitness line" (field escape speed = maximum laboratory speed) are most likely to bear fruit for such studies. 相似文献