全文获取类型
收费全文 | 233篇 |
免费 | 16篇 |
国内免费 | 1篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 11篇 |
2020年 | 10篇 |
2019年 | 5篇 |
2018年 | 9篇 |
2017年 | 7篇 |
2016年 | 15篇 |
2015年 | 17篇 |
2014年 | 15篇 |
2013年 | 28篇 |
2012年 | 26篇 |
2011年 | 15篇 |
2010年 | 6篇 |
2009年 | 11篇 |
2008年 | 9篇 |
2007年 | 4篇 |
2006年 | 2篇 |
2005年 | 5篇 |
2004年 | 5篇 |
2003年 | 10篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1976年 | 1篇 |
1973年 | 3篇 |
1972年 | 1篇 |
1969年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有250条查询结果,搜索用时 15 毫秒
71.
Ozgur Taskin 《Evolution》2011,4(3):467-477
This qualitative research aims at first defining how pre-service science teachers think regarding the theory of evolution
(TOE) with a particular hands-on and minds-on activity (The article by O’Brien (Am Biol Teach 62(8):578–582, 2000) entitled A toilet paper timeline of evolution: 5 E cycle on the concept of scale is modified and applied in the present
research as an intervention process.) Finally, specific suggestions in instructional techniques are offered based on a geological
time scale. At the end of intervention, the research follows how participants respond to what they found out or came across.
If participants had common misconceptions regarding the TOE, these are revealed. The present research was conducted in two
spring semesters of 2009 and 2010 in a geology course. The participant number of the study was 129. The research lasted three weeks.
Research results showed that participants were generally misinformed regarding conceptual knowledge of the TOE. Approximately
half of the participants did not believe (the term believing in or acceptance of the TOE does not affect research findings)
in the TOE. Mostly, they thought that there is no place for human evolution in Islam. Few of them could reconcile scientific
information with their own Islamic point of view. Even though they did not believe in the TOE, most of them accepted that
they did not have adequate knowledge regarding the TOE. They mostly said they were shocked about the first appearance of human
beings in the geological time scale, which is the main issue in the present research. After intervention, conceptual change
was considerable, though this is a secondary concern. The results also show that even though students were quite prejudiced
regarding the TOE, they were ready to explore it deeply. Such concrete activities might be helpful to push students to think
over the TOE. However, there are numerous barriers such as ill-prepared science textbooks and websites, unwillingness of instructors,
and official policy of the Ministry of National Education. 相似文献
72.
Nura Abdullahi Elias Saion Abdul Halim Shaari Naif Mohammed Al-Hada Aysar Keiteb 《PloS one》2015,10(5)
MWCNTs/TiO2 nanocomposite was prepared by oxidising MWCNT in H2SO4/HNO3 then decorating it with TiO2-p25 nanopowder. The composites were characterised using XRD, TEM, FT-IR PL and UV−vis spectroscopy. The TEM images have shown TiO2 nanoparticles immobilised onto the sidewalls of the MWCNTs. The UV-vis spectrum confirms that the nanocomposites can significantly absorb more light in the visible regions compared with the commercial TiO2 (P25). The catalytic activity of these nanocomposites was determined by photooxidation of MB aqueous solution in the presence of visible light. The MWCNTs/TiO2 (1:3) mass ratio showed maximum degradation efficiency. However, its activity was more favourable in alkaline and a neutral pH than an acidic medium. 相似文献
73.
Johanna Nilsson Adnan Halim Erik Larsson Ali-Reza Moslemi Anders Oldfors Göran Larson Jonas Nilsson 《Biochimica et Biophysica Acta - Proteins and Proteomics》2014,1844(2):398-405
Glycogen synthesis is initiated by self-glucosylation of the glycosyltransferases glycogenin-1 and -2 that, in the presence of UDP-glucose, form both the first glucose-O-tyrosine linkage, and then stepwise add a series of α1,4-linked glucoses to a growing chain of variable length. Glycogen-1 and -2 coexist in liver glycogen preparations where the proteins are known to form homodimers, and they also have been shown to interact with each other. In order to study how glycogenin-1 and -2 interactions may influence each other's glucosylations we setup a cell-free expression system for in vitro production and glucosylation of glycogenin-1 and -2 in various combinations, and used a mass spectrometry based workflow for the characterization and quantitation of tryptic glycopeptides originating from glycogenin-1 and -2. The analysis revealed that the self-glucosylation endpoint was the incorporation of 4–8 glucose units on Tyr 195 of glycogenin-1, but only 0–4 glucose units on Tyr-228 of glycogenin-2. The glucosylation of glycogenin-2 was enhanced to 2–4 glucose units by the co-presence of enzymatically active glycogenin-1. Glycogenin-2 was, however, unable to glucosylate inactive glycogenin-1, at least not an enzymatically inactivated Thr83Met glycogenin-1 mutant, recently identified in a patient with severe glycogen depletion. 相似文献
74.
Azza Mohamed Noor El-Deen Hoda Mohamed Abdel Halim Shata Mohamed Abdel Fattah Farid 《Annals of microbiology》2014,64(2):627-637
Eleven different Aspergillus strains were evaluated for their ability to produce β-glucosidase using sugar cane bagasse as a sole carbon source under solid state fermentation (SSF). The most potent strains, A. niger NRC 7 (674.6 U/g ds) and A. oryzae NRRL 447 (83 U/g ds), were used in a mixed culture to enhance β-glucosidase production by co-culturing under SSF. In mixed culture, β-glucosidase of the two strains (814 U/g ds) was nearly 1.2- and 9.8-fold than that of monocultures of A. niger NRC 7A and A. oryzae NRRL 447, respectively. Optimization of the culture parameters, initial pH value, moisture content, inoculum size and ratios of the two strains. and incubation time exhibited a significant increase in β-glucosidase production (1,893 U/g ds) than before optimization. Single feeding with citrate-phosphate buffer, succinate buffer, casein. and soybean flour individually after the third day of the fermentation time and controlling the moisture content at 90 % (w/w) induced β-glucosidase production. Maximum enzyme production increased up to 2.1-fold compared to 2,188 U/g ds during normal batch culture. Among nitrogen sources, soybean flour gave the highest β-glucosidase (4,578 U/g ds). while urea reduced β-glucosidase production (1,693 U/g ds). However, the combination of buffers with soybean flour through two fed cycles resulted in a decrease of the enzyme than single fed with buffers or soybean flour alone. 相似文献
75.
76.
77.
Halim Anis Syahira Abdul Mohamad Faridah Ahmad Fisal Ismail Noraznawati Chilek Tuan Zainazor Tuan Ahmad Ahmad Shamsuddin Cob Zaidi Che Yusof Ku Mohd Kalkausar Ku 《Hydrobiologia》2021,848(4):841-855
Hydrobiologia - The population of horseshoe crabs, Tachypleus gigas, in Malaysian waters is declining due to overexploitation, pollution, and loss of natural habitats. As an initiative to increase... 相似文献
78.
Muhamad Aidilfitri Mohamad Roslan Nur Qaiyyum Ummi Aiman Jefri Nurhidayah Ramlee Nor Aini Abdul Rahman Nur Hazlin Hazrin Chong Hamidun Bunawan Izwan Bharudin Mohd. Hafiz Abd. Kadir Masita Mohammad Halim Razali 《Saudi Journal of Biological Sciences》2021,28(5):3001-3012
Food waste (FW) minimization at the source by using food waste biodigester (FWBs) has a vast potential to lower down the impact of increasing organic fraction in municipal solid waste generation. To this end, this research sought to check the performance of locally isolated hydrolase-producing bacteria (HPB) to improve food waste biodegradation rate. Two under-explored HPB identified as Bacillus paralicheniformis GRA2 and Bacillus velezensis TAP5 were able to produce maximum amylase, cellulase, protease and lipase activities, and demonstrated a significant hydrolase synergy in co-culture fermentation. In vitro biodegradation analysis of both autoclaved and non-autoclaved FW revealed that the HPB inoculation was effective to degrade total solids (>62%), protein (>19%), total fat (>51), total sugar (>86%), reducing sugar (>38%) and starch (>50%) after 8-day incubation. All co-culture treatments were recorded superior to the respective monocultures and the uninoculated control. The results of FW biodegradation using batch-biodigester trial indicated that the 1500 mL and 1000 mL inoculum size of HPB inoculant reached a plateau on the 4th day, with gross biodegradation percentage (GBP) of >85% as compared to control (66.4%). The 1000 mL inoculum was sufficient to achieve the maximum GBP (>90%) of FW after an 8-day biodigestion in a FWB. 相似文献
79.
Majdi Nagara Afaf Tiar Nizar Ben Halim Faten Ben Rhouma Olfa Messaoud Yosra Bouyacoub Rym Kefi Saida Hassayoun Noura Zouari Mohamed Slim Ben Ammar Sonia Abdelhak Jalel Chemli 《Gene》2013
Background
Primary hyperoxaluria type 1 (PH1) is an autosomal recessive inherited metabolic disease, characterized by progressive kidney failure due to renal deposition of calcium oxalate. Mutations in the AGXT gene, encoding the liver-specific enzyme alanine glyoxylate aminotransferase, are responsible for the disease. We aimed to determine the mutational spectrum causing PH1 and to provide an accurate tool for diagnosis as well as for prenatal diagnosis in the affected families.Methods
Direct sequencing was used to detect mutations in the AGXT gene in DNA samples from 13 patients belonging to 12 Tunisian families.Results
Molecular analysis revealed five mutations causing PH1 in Tunisia. The mutations were identified along exons 1, 2, 4, 5 and 7. The most predominant mutations were the Maghrebian “p.I244T” and the Arabic “p.G190R”. Furthermore, three other mutations characteristic of different ethnic groups were found in our study population. These results confirm the mutational heterogeneity related to PH1 in Tunisian population. All the mutations are in a homozygous state, reflecting the high impact of endogamy in our population.Conclusion
Mutation analysis through DNA sequencing can provide a useful first line investigation for PH1. This identification could provide an accurate tool for prenatal diagnosis, genetic counseling and screen for potential presymptomatic individuals. 相似文献80.
Laurence Conraux Catherine Pech Halim Guerraoui Denis Loyaux Pascual Ferrara Jean-Claude Guillemot Vincent Meininger Pierre-Fran?ois Pradat Fran?ois Salachas Ga?lle Bruneteau Nadine Le Forestier Lucette Lacomblez 《PloS one》2013,8(11)
The diagnostic of Amyotrophic lateral sclerosis (ALS) remains based on clinical and neurophysiological observations. The actual delay between the onset of the symptoms and diagnosis is about 1 year, preventing early inclusion of patients into clinical trials and early care of the disease. Therefore, finding biomarkers with high sensitivity and specificity remains urgent. In our study, we looked for peptide biomarkers in plasma samples using reverse phase magnetic beads (C18 and C8) and MALDI-TOF mass spectrometry analysis. From a set of ALS patients (n=30) and healthy age-matched controls (n=30), C18- or C8-SVM-based models for ALS diagnostic were constructed on the base of the minimum of the most discriminant peaks. These two SVM-based models end up in excellent separations between the 2 groups of patients (recognition capability overall classes > 97%) and classify blinded samples (10 ALS and 10 healthy age-matched controls) with very high sensitivities and specificities (>90%). Some of these discriminant peaks have been identified by Mass Spectrometry (MS) analyses and correspond to (or are fragments of) major plasma proteins, partly linked to the blood coagulation. 相似文献