全文获取类型
收费全文 | 527篇 |
免费 | 36篇 |
出版年
2023年 | 9篇 |
2022年 | 20篇 |
2021年 | 11篇 |
2020年 | 5篇 |
2019年 | 11篇 |
2018年 | 15篇 |
2017年 | 15篇 |
2016年 | 18篇 |
2015年 | 25篇 |
2014年 | 30篇 |
2013年 | 34篇 |
2012年 | 47篇 |
2011年 | 44篇 |
2010年 | 28篇 |
2009年 | 18篇 |
2008年 | 29篇 |
2007年 | 22篇 |
2006年 | 20篇 |
2005年 | 21篇 |
2004年 | 12篇 |
2003年 | 18篇 |
2002年 | 14篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 4篇 |
1995年 | 2篇 |
1993年 | 4篇 |
1992年 | 8篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1980年 | 2篇 |
1976年 | 3篇 |
1975年 | 6篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1967年 | 1篇 |
1966年 | 4篇 |
1963年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有563条查询结果,搜索用时 15 毫秒
551.
Ahmed M. Salem Assoc. Prof. Dr. Nada M. Mostafa Prof. Dr. Eman Al-Sayed Dr. Iten M. Fawzy Prof. Dr. Abdel Nasser B. Singab 《化学与生物多样性》2023,20(7):e202300200
Alzheimer's disease (AD) is a major health problem. Cholinergic transmission is greatly affected in AD. Phytochemical investigation of the alkaloid rich fraction (AF) of Erythrina corallodendron L leaves resulted in isolation of five known alkaloids: erysodine, erythrinine, 8-oxoerythrinine, erysovine N-oxide and erythrinine N-oxide. In this study, eysovine N-oxide was reported for the second time in nature. AF was assayed for cholinesterase inhibition at the concentration of 100 μg mL−1. AF showed a higher percent inhibition for butyrylcholinesterase enzyme (BuChE) (83.28 %) compared to acetylcholinesterase enzyme (AChE) (64.64 %). The isolated alkaloids were also assayed for their anti-BuChE effect. In-silico docking study was done for the isolated compounds at the binding sites of AChE and BuChE to determine their binding pattern and interactions, also molecular dynamics were estimated for the compound displaying the best fit for AChE and BuChE. In addition, ADME parameters and toxicity were predicted for the isolated alkaloids compared to donepezil. 相似文献
552.
Nada Pipan 《Cell and tissue research》1966,73(4):534-539
Zusammenfassung 13, 15 und 17 Tage alte Mäuseembryonen wurden zwei oder drei Tage vor der Untersuchung mit 1200, 1500, 1700 bzw. 1800 r in utero bestrahlt. In den Leberzellen 13 und 15 Tage alter Embryonen fanden wir mehr oder weniger stark geschwollene Mitochondrien, deren Oberfläche durch einzelne oder mehrere Invaginationen vergrößert ist. In das Mitochondrium hineinragendes Cytoplasma wird manchmal ganz eingeschlossen und enthält oft konzentrische Membrangebilde. Diese Befunde werden im Zusammenhang mit den von anderen Autoren bobachteten pathologischen Veränderungen der Lebermitochondrien diskutiert.
Summary 13, 15, and 17 days old mouse embryos were irradiated with 1200, 1500, 1700, or 1800 r. Their livers were examined two or three days after the irradiation. The liver cells of the 13 and 15 days old embryos showed more or less swollen mitochondria, the surface of which was often increased by one or more invaginations. The surrounding cytoplasm protruded into the mitochondria and was occasionally completely enclosed. Often these cytoplasmic protrusions contained concentric membraneous structures. These findings are discussed taking into consideration the pathologic changes in liver mitochondria described by other authors.相似文献
553.
554.
Nada Ćosić Štěpánka Říčanová Josef Bryja Aleksandra Penezić Duško Ćirović 《Conservation Genetics》2013,14(2):345-354
The European ground squirrel (EGS) (Spermophilus citellus) populations of Vojvodina (Serbia) represent the southernmost part of its distribution in the Pannonian lowland. For species with low dispersal abilities a presence of even weak barriers can have significant influence on genetic structure among adjacent populations. We examined here the effects of habitat fragmentation and river barriers on the genetic structure of the EGS based on 12 microsatellite loci. Bayesian clustering methods were used as additions to classical population genetic approaches. We found that EGS populations in Vojvodina are highly fragmented, but their genetic variation is still higher than in peripheral populations in Central Europe. Populations in Vojvodina consistently grouped into three genetic clusters. The Danube, but not the Tisza River, represents an important barrier to gene flow. EGS populations in the studied area did not show the signs of recent genetic bottlenecks, as would be expected from observations of recent population declines. Conservation strategy should be focused on maintenance of remained suitable habitats and optimal population sizes. 相似文献
555.
As the minority group frequently at the centre of public fear in the post-9/11 era, Arab Americans’ own sentiment toward, and concerns with, crime, has eluded scholarly attention. This study investigated their fear of crime net of five empirically validated fear of crime theoretical models. Face-to-face interviews with a random sample of Arab and non-Arab households in Metro-Detroit, Michigan indicated that net of all controls, Arab Americans experienced significantly higher levels of fear concerning both general and bias crimes than non-Arab Americans. The greater fear among Arab Americans calls for policy and practice change, and moving from perceiving Arab Americans as a major “source” of fear, to “carriers” of fear who are in need of more attention, care, and assistance. 相似文献
556.
557.
Lamia Ayed Nedra Asses Nadia Chammem Nada Ben Othman Moktar Hamdi 《Biodegradation》2017,28(2-3):125-138
Table olive processing wastewaters constitute a dangerous environmental problem in the Mediterranean countries because of their large volumes, high organic matter and salt concentration. The quantity and the characteristics of wastewaters produced, and thus, their environmental impact, varied depending on the season, varieties, soil and process employed. Several chemicals, biological and combined technologies have proven effective at bringing down organic pollution and toxicity of these effluents. Advanced oxidation processes have recognized as highly efficient treatments for the degradation of organic matter. Nonetheless, complete mineralization is generally expensive without salt removal. Biological processes are the most environmentally compatible and least-expensive treatment methods, but these operations do not always provide satisfactory results. This article surveys the current available technologies and suggests an effective, cheaper alternative for the recycling and the valorization of green table olives wastewaters. 相似文献
558.
Dario Kremer Ivna Dragojević Müller Valerija Dunkić Dubravka Vitali Edith Stabentheiner Andreas Oberländer Nada Bezić Ivan Kosalec 《Central European Journal of Biology》2012,7(5):941-947
Chemical composition of the essential oil (analysed by GC-FID and GC-MS), the content of macroelements and trace elements (analysed by ICP-AES), and antimicrobial activities were investigated in Teucrium arduini L. from Mt Biokovo (Croatia). Additionally, a study on the types and distribution of glandular trichomes which produce essential oils was investigated. The oil was characterized by a high concentration of sesquiterpene hydrocarbons (68.5%) of which β-caryophyllene (32.9%) and germacrene D (16.4%) being the major compounds. Among the macroelements, the content of calcium was the highest (9772 mg/kg), while the content of sodium was the smallest (117.74 mg/kg). Among the micronutrients, the most represented element was iron (72.07 mg/kg). The content of each investigated toxic metal (As, Hg, Pb, Cd and Cr) was below permissible levels. The essential oils showed antimicrobial activity against bacterial species tested, with MIC values ranging from 6.25 mg/mL to 37.50 mg/mL. Fungal species were susceptible with MIC values from 7.81 mg/mL and 25.00 mg/mL. 相似文献
559.
Stephan Brandt Christina Walz Martina Schad Nada Pavlovic Julia Kehr 《Plant Molecular Biology Reporter》2003,21(4):417-427
Many physiological processes are limited to specific tissues or even specific cell types. Analysing entire plants or organs
results in averaged data of all cell types contained in the sample; thus, specific metabolic functions cannot be assigned
to individual cell types. A higher spatial resolution is required. By microdissecting plant organs, homogeneous material can
be obtained. If a suitable amount of material is collected, standard analytical methods can be applied to elucidate cell type-specific
processes. The collection of sufficient quantities of homogeneous material can be done by means of mechanical microdissection.
This technique is a low-cost alternative to laser-coupled microdissection techniques. Here we describe a protocol for chisel-assisted
mechanical microdissection of embedded plant material and demonstrate that the collected material is suitable to obtain nucleic
acids and proteins. 相似文献
560.
Nada Stankovic Lidija Senerovic Tatjana Ilic-Tomic Branka Vasiljevic Jasmina Nikodinovic-Runic 《Applied microbiology and biotechnology》2014,98(9):3841-3858
The growing demand to fulfill the needs of present-day medicine in terms of novel effective molecules has lead to reexamining some of the old and known bacterial secondary metabolites. Bacterial prodigiosins (prodiginines) have a long history of being re markable multipurpose compounds, best examined for their anticancer and antimalarial activities. Production of prodigiosin in the most common producer strain Serratia marcescens has been described in great detail. However, few reports have discussed the ecophysiological roles of these molecules in the producing strains, as well as their antibiotic and UV-protective properties. This review describes recent advances in the production process, biosynthesis, properties, and applications of bacterial prodigiosins. Special emphasis is put on undecylprodigiosin which has generally been a less studied member of the prodigiosin family. In addition, it has been suggested that proteins involved in undecylprodigiosin synthesis, RedG and RedH, could be a useful addition to the biocatalytic toolbox being able to mediate regio- and stereoselective oxidative cyclization. Judging by the number of recent references (216 for the 2007–2013 period), it has become clear that undecylprodigiosin and other bacterial prodigiosins still hold surprises in terms of valuable properties and applicative potential to medical and other industrial fields and that they still deserve continuing research curiosity. 相似文献