全文获取类型
收费全文 | 203篇 |
免费 | 10篇 |
出版年
2021年 | 6篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 5篇 |
2016年 | 9篇 |
2015年 | 10篇 |
2014年 | 8篇 |
2013年 | 8篇 |
2012年 | 21篇 |
2011年 | 22篇 |
2010年 | 13篇 |
2009年 | 6篇 |
2008年 | 7篇 |
2007年 | 10篇 |
2006年 | 7篇 |
2005年 | 12篇 |
2004年 | 10篇 |
2003年 | 12篇 |
2002年 | 9篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 3篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1986年 | 2篇 |
1982年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1963年 | 1篇 |
1961年 | 3篇 |
排序方式: 共有213条查询结果,搜索用时 15 毫秒
91.
Gaurina Srcek V Radosević K Kniewald H Slivac I Kmetic I Kniewald Z 《In vitro cellular & developmental biology. Animal》2009,45(1-2):28-31
Growth factors from neural tissues have been described as potent mitogens for a wide variety of mesoderm- and ectoderm-derived cells in vitro. We used porcine brain extract for in vitro testing of proliferation properties on primary ovarian cells, uterine cells, and cardiomyocytes in culture as well as for BHK-21 [C-13] cell line. The addition of this extract accelerates proliferation in all examined cultures. It also lowers serum requirement and shortens the cultivation period for BHK-21 [C-13] cells. Fibroblast growth factors from brain of different species, but not porcine, are already characterized and their proliferative effect proved. Therefore, we purified, determined, and confirmed the presence of basic fibroblast growth factor in porcine brain extract by Western blot analysis and showed its biological activity on BHK-21 [C-13] cells. 相似文献
92.
Stephan Pabinger Gerhard G Thallinger René Snajder Heiko Eichhorn Robert Rader Zlatko Trajanoski 《BMC bioinformatics》2009,10(1):268
Background
Since its introduction quantitative real-time polymerase chain reaction (qPCR) has become the standard method for quantification of gene expression. Its high sensitivity, large dynamic range, and accuracy led to the development of numerous applications with an increasing number of samples to be analyzed. Data analysis consists of a number of steps, which have to be carried out in several different applications. Currently, no single tool is available which incorporates storage, management, and multiple methods covering the complete analysis pipeline. 相似文献93.
Morshed K Polz-Dacewicz M Szymański M Smoleń A 《Folia histochemica et cytobiologica / Polish Academy of Sciences, Polish Histochemical and Cytochemical Society》2010,48(3):398-402
The use of formalin-fixed paraffin-embedded (FFPE) tissues for HPV DNA detection by PCR from biopsy materials is not entirely clear in retrospective studies. The aim of our study was to evaluate the usefulness and efficiency of FFPE tissues from laryngeal cancer (LSCC) in HPV detection by immunohistochemistry reaction (IHC) and PCR-DNA enzyme immunoassay method (PCR/DEIA) and to compare with HPV detection from DFT. HPV-DNA was amplified from 54 FFPE tissues from LSCC specimens by the short PCR fragment (SPF10) primer set using PCR/DNA method and monoclonal anti Human Papillomavirus antibodies in IHC. In the same patients 54 specimens were collected and immediately deep-frozen and stored at (-70°C) to (-80°C). All the FFPE and deep-frozen tissue (DFT) specimens were positive for β-globin amplification. HPV was detected by two methods (SPF10 PCR/DEIA and IHC) in 14 (25.92%) out of 54 specimens from FFPE. Significant differences were found between the HPV detection using PCR/DEIA method and IHC method in FFPE tissues. The comparative analysis of the 54 samples after assuming PCR method in FFPE tissues showed accuracy of 92.6%, sensitivity of 90.5% and specificity of 93.9%. The FFPE tissues method has high sensitivity, specificity and accuracy when used to detect HPV DNA by PCR reaction and it is comparable to DFT results. DNA quality of FFPE samples is adequate and it can be used in HPV-DNA detection and in retrospective studies on LSCC. 相似文献
94.
Anita Kriško Zlatko Smole Gaelle Debret Miroslav Radman 《Journal of molecular biology》2010,402(5):775-782
Water loss or desiccation is among the most life-threatening stresses. It leads to DNA double-strand breakage, protein aggregation, cell shrinkage, and low water activity precluding all biological functions. Yet, in all kingdoms of life, rare organisms are resistant to desiccation through prevention or reversibility of such damage. Here, we explore possible hallmarks of prokaryotic desiccation tolerance in their proteomes. The content of unstructured, low complexity (LC) regions was analyzed in a total of 460 bacterial and archaeal proteomes.It appears that species endowed with proteomes abundant in unstructured hydrophilic LC regions are desiccation-tolerant or sporulating bacteria, halophilic archaea and bacteria, or host-associated species. In the desiccation- and radiation-resistant bacterium Deinococcus radiodurans, most proteins that contain large hydrophilic LC regions have unassigned function, but those with known function are mostly involved in diverse cellular recovery processes. Such LC regions are typically absent in orthologous proteins in desiccation-sensitive species. D. radiodurans encodes also special LC proteins, akin to those associated with desiccation resistance of plant seeds and some plants and animals. Therefore, we postulate that large unstructured hydrophilic LC regions and proteins provide for cellular resistance to dehydration and we discuss mechanisms of their protective activity. 相似文献
95.
Christoph Nusshold Manfred Kollroser Harald Köfeler Gerald Rechberger Helga Reicher Andreas Üllen Eva Bernhart Sabine Waltl Ingrid Kratzer Albin Hermetter Hubert Hackl Zlatko Trajanoski Andelko Hrzenjak Ernst Malle Wolfgang Sattler 《Free radical biology & medicine》2010,48(12):1588-1600
Recent observations link myeloperoxidase (MPO) activation to neurodegeneration. In multiple sclerosis MPO is present in areas of active demyelination where the potent oxidant hypochlorous acid (HOCl), formed by MPO from H2O2 and chloride ions, could oxidatively damage myelin-associated lipids. The purpose of this study was (i) to characterize reaction products of sphingomyelin (SM) formed in response to modification by HOCl, (ii) to define the impact of exogenously added SM and HOCl-modified SM (HOCl-SM) on viability parameters of a neuronal cell line (PC12), and (iii) to study alterations in the PC12 cell proteome in response to SM and HOCl-SM. MALDI-TOF-MS analyses revealed that HOCl, added as reagent or generated enzymatically, transforms SM into chlorinated species. On the cellular level HOCl-SM but not SM induced the formation of reactive oxygen species. HOCl-SM induced severely impaired cell viability, dissipation of the mitochondrial membrane potential, and activation of caspase-3 and DNA damage. Proteome analyses identified differential expression of specific subsets of proteins in response to SM and HOCl-SM. Our results demonstrate that HOCl modification of SM results in the generation of chlorinated lipid species with potent neurotoxic properties. Given the emerging connections between the MPO–H2O2–chloride axis and neurodegeneration, this chlorinating pathway might be implicated in neuropathogenesis. 相似文献
96.
In this study the effects of ammonium and lactate on a culture of channel catfish ovary (CCO) cells were examined. We also
made investigation on the influence of glutamine, since our previous research revealed that this amino acid stimulated CCO
cell growth more than glucose in a concentration-dependent manner. The effect of ammonium in cell culture included the considerable
decrease in cell growth rate with eventual growth arrest as well as the retardation of glucose consumption. At ammonium concentrations
above 2.5 mM, the cells displayed specific morphological changes. The effect of lactate was different to that of ammonium
since the cell growth rate was progressively decreasing with the increase of lactate concentration, whereas the glucose consumption
rate remained almost unchanged. Besides that, it was found that lactate was steadily eliminated from the culture medium when
its initial concentration was relatively high. The influence of glutamine on CCO cell propagation showed that nutrient requirements
of this cell line were mainly dependent on glutamine rather than glucose. The increase in glutamine concentration led to the
increase in cell growth rate and consequent ammonia accumulation while the glucose utilization and lactate production were
reduced. Without glutamine in culture medium cell growth was arrested. However, the lack of glucose reversed the stimulating
effect of glutamine by decreasing cell growth rate and affecting amino acid utilization. 相似文献
97.
Marcela Krečmerová Petr Jansa Martin Dračínský Petra Sázelová Václav Kašička Johan Neyts Joeri Auwerx Eleonóra Kiss Nesya Goris George Stepan Zlatko Janeba 《Bioorganic & medicinal chemistry》2013,21(5):1199-1208
New large-scale synthetic approach to antiretroviral agent 9-[2-(R)-(phosphonomethoxy)propyl]-2,6-diaminopurine, (R)-PMPDAP, was developed. Reaction of (R)-propanediol carbonate with 2,6-diaminopurine afforded exclusively (R)-9-(2-hydroxypropyl)-2,6-diaminopurine which was subsequently used for introduction of a phosphonomethyl residue using TsOCH2P(O)(OiPr)2 or BrCH2P(O)(OiPr)2 followed by deprotection of ester groups. All minor ingredients and by-products formed during the process were identified and further studied. The final product was obtained in high yield and its high enantiomeric purity (>99%) was confirmed by chiral capillary electrophoretic analysis using β-cyclodextrin as a chiral selector. Antiretroviral activity data of (R)-PMPDAP and its diverse prodrugs against HIV and FIV were investigated. Akin to (R)-PMPDAP, both prodrugs inhibit FIV replication in a selective manner. Compared to the parent molecule, the amidate prodrug was 10-fold less active against FIV in cell culture, whereas the alkoxyalkyl ester prodrug was 200-fold more potent in inhibiting FIV replication in vitro. 相似文献
98.
Vesna Selaković Snežana Rauš Balind Lidija Radenović Zlatko Prolić Branka Janać 《Cell biochemistry and biophysics》2013,66(3):513-521
The aim of study was to investigate the effects of extremely low frequency magnetic field (ELF-MF; 50 Hz; 0.1, 0.25 and 0.5 mT) on oxidative stress in the brain of 3- (adult) and 10-month-old (middle-aged) gerbils. Nitric oxide (NO) level, superoxide (O2 ?) production, superoxide dismutase (SOD) activity, and index of lipid peroxidation (ILP) were measured in the forebrain cortex, striatum, hippocampus, and cerebellum immediately and 3 days after cessation of 7-day exposure. In all gerbils, ELF-MF significantly increased oxidative stress in all tested brain regions. This effect was correlated with the value of magnetic induction and was higher in middle-aged gerbils. Three days after cessation of exposure, the values of examined parameters were closer to control levels. In adult gerbils, the effect of ELF-MF of 0.1 mT on NO level, O2 ? production and SOD activity was almost fully disappeared, and ILP was at the control level regardless of the value of magnetic induction. In middle-aged gerbils, the effect of ELF-MF was still present but to a lesser degree than those observed immediately after cessation of exposure. These findings pointed out the ability of ELF-MF to induce age- and magnetic induction-dependent modification of oxidative stress in the brain. 相似文献
99.
Petrin Z 《Oecologia》2011,167(2):513-524
Much recent ecological research has centred on the interrelations between species diversity and ecological processes. In the
present study, I show how species traits may aid in comprehending ecology by studying the link between an environmental variable
and functional traits. I examined the composition of species traits with a theoretically underpinned relationship to ecological
processes along a pH gradient. I focused on body size, reproductive output, life cycle length and feeding habit of mayflies
and stoneflies. In mayfly assemblages, I found smaller body size, greater reproductive output, faster life cycles and a larger
proportion of gathering collectors and scrapers with increasing pH. In stonefly assemblages, I found smaller body size, greater
reproductive output and faster life cycles at sites with a history of long-term natural acidification, but no clear trends
in feeding habits and in most traits where acidification is anthropogenic. The results suggest that mayflies and stoneflies
exhibit different ecological functions following different ecological strategies. Mayflies follow an opportunistic strategy
relative to stoneflies, likely facilitating high rates of ecological processes with respect to the autotrophic resource base
at neutral sites. Relative to mayflies, stoneflies follow an equilibrium strategy contributing to ecological functioning in
heterotrophic ecosystems and likely maintaining heterotrophic processes despite the erosion of species diversity in response
to acidification. The rules governing an ecological community may be more readily revealed by studying the distribution of
species traits instead of species diversity; by studying traits, we are likely to improve our understanding of the workings
of ecological communities. 相似文献
100.
Hayes TB Anderson LL Beasley VR de Solla SR Iguchi T Ingraham H Kestemont P Kniewald J Kniewald Z Langlois VS Luque EH McCoy KA Muñoz-de-Toro M Oka T Oliveira CA Orton F Ruby S Suzawa M Tavera-Mendoza LE Trudeau VL Victor-Costa AB Willingham E 《The Journal of steroid biochemistry and molecular biology》2011,127(1-2):64-73
Atrazine is the most commonly detected pesticide contaminant of ground water, surface water, and precipitation. Atrazine is also an endocrine disruptor that, among other effects, alters male reproductive tissues when animals are exposed during development. Here, we apply the nine so-called "Hill criteria" (Strength, Consistency, Specificity, Temporality, Biological Gradient, Plausibility, Coherence, Experiment, and Analogy) for establishing cause-effect relationships to examine the evidence for atrazine as an endocrine disruptor that demasculinizes and feminizes the gonads of male vertebrates. We present experimental evidence that the effects of atrazine on male development are consistent across all vertebrate classes examined and we present a state of the art summary of the mechanisms by which atrazine acts as an endocrine disruptor to produce these effects. Atrazine demasculinizes male gonads producing testicular lesions associated with reduced germ cell numbers in teleost fish, amphibians, reptiles, and mammals, and induces partial and/or complete feminization in fish, amphibians, and reptiles. These effects are strong (statistically significant), consistent across vertebrate classes, and specific. Reductions in androgen levels and the induction of estrogen synthesis - demonstrated in fish, amphibians, reptiles, and mammals - represent plausible and coherent mechanisms that explain these effects. Biological gradients are observed in several of the cited studies, although threshold doses and patterns vary among species. Given that the effects on the male gonads described in all of these experimental studies occurred only after atrazine exposure, temporality is also met here. Thus the case for atrazine as an endocrine disruptor that demasculinizes and feminizes male vertebrates meets all nine of the "Hill criteria". 相似文献