全文获取类型
收费全文 | 735篇 |
免费 | 37篇 |
国内免费 | 4篇 |
专业分类
776篇 |
出版年
2023年 | 18篇 |
2022年 | 14篇 |
2021年 | 40篇 |
2020年 | 20篇 |
2019年 | 22篇 |
2018年 | 28篇 |
2017年 | 29篇 |
2016年 | 37篇 |
2015年 | 38篇 |
2014年 | 45篇 |
2013年 | 63篇 |
2012年 | 45篇 |
2011年 | 55篇 |
2010年 | 36篇 |
2009年 | 29篇 |
2008年 | 35篇 |
2007年 | 25篇 |
2006年 | 37篇 |
2005年 | 29篇 |
2004年 | 26篇 |
2003年 | 19篇 |
2002年 | 13篇 |
2001年 | 7篇 |
2000年 | 7篇 |
1999年 | 7篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1970年 | 4篇 |
1968年 | 2篇 |
1967年 | 1篇 |
排序方式: 共有776条查询结果,搜索用时 15 毫秒
741.
Ahmet?Emin?Senturk Ahmet?Sinan?Oktem Alp?Er?S.?KonukmanEmail author 《Journal of molecular modeling》2018,24(2):43
The effect of defect locations on the mechanical properties of armchair graphene nanoribbons (AGNRs) and the various configurations of nitrogen (N) doping on the mechanical properties of AGNRs were examined using molecular dynamics (MD) simulations. The variation of the Young’s modulus (YM) and the ultimate tensile strength (UTS) of pyridinic-N, graphitic-N, and pyrrolic-N by increasing the concentration of N doping was investigated. The results of MD simulations show that the defect location has a significant effect on the UTS and failure strain (FS) of AGNRs in both vertical and horizontal directions. In the horizontal direction, variations of the UTS and FS are lower than in the vertical direction. On the other hand, the variations of the YM is almost similar in vertical and horizontal directions. The results of this work indicate that the UTS and FS of AGNRs are more sensitive than the YM of AGNRs for different defect directions. Pyridinic-N improves the mechanical properties of the defective AGNR and performs better YM and UTS values than the graphitic-N. Substitution N atoms, which are located at the defective sites and/or at the edges of AGNRs, are mechanically more favorable. Pyrrolic-N configuration has the lowest mechanical properties among the other configurations. Furthermore, pyrrolic-N with Stone-Wales-1 (SW-1) type of defect has higher mechanical properties than pyrrolic-N with Stone-Wales-2 (SW-2) type of defect. 相似文献
742.
743.
744.
745.
Sahin Cigdem Mutlu Dogukan Nasirli Farid Mahmoudi Ghodrat Zubkov Fedor I. Arslan Sevki Dogan Nazime Mercan 《Biometals》2021,34(3):701-713
BioMetals - This study represents synthesis, characterization, screening of antibiofilm efficacy, and cytotoxicity of iridium bis-terpyridine complexes. The complexes were characterized by NMR, MS,... 相似文献
746.
The geometries, relative stabilities of some 4(7) and 5(6) substituted 2-hydroxybenzimidazole derivatives were calculated with full geometry optimization using AM1 and PM3 in aqueous phase. With the exception of molecules 4, 6 and 7 for all the 4(7) and 5(6) substituted 2-hydroxybenzimidazole derivatives the 3H and keto forms were found to be favored. 相似文献
747.
Burcu?Sigmaz Guleray?AgarEmail author Esra?Arslan Murat?Aydin Mahmut?Sinan?Taspinar 《Acta Physiologiae Plantarum》2015,37(11):251
This study aimed to research the impact of putrescine against the long terminal repeat (LTR) retrotransposon polymorphisms (Nikita-E2647, Sukkula, Stowaway, WLTR2105 and 5′LTR) induced by salinity stress in Triticum aestivum using inter-retrotransposon amplified polymorphism (IRAP) assay. The results showed that the LTR retrotransposon polymorphisms can be induced by all treated sodium chloride (NaCl) doses (0, 50, 100, 200 and 300 mM NaCl). On the other hand, the LTR retrotransposons polymorphisms were decreased effectively by treatment with putrescine (0, 0.01, 0.1 and 1 mM) together with NaCl. These results suggest that putrescine could effectively inhibit salt-induced LTR retrotransposon polymorphisms, and putrescine positively contributed to salt stress tolerance. 相似文献
748.
749.
Genetic and geographic polymorphism of cultivated tobaccos (Nicotiana tabacum) in Turkey 总被引:1,自引:0,他引:1
Nicotiana tabacum (2n = 48) is a natural amphidiploid and shows a distribution over a geographical area in eastern Anatolia. Random amplified polymorphic
DNA (RAPD) technique was used to evaluate both genetic diversity among 21 primitive tobacco accessions comparing flue cure
virginia genotype (FCV) and their geographical polymorphism as a source of genetic variations for breeding programs. Only
13 of all the 60 random primers used in RAPD showed polymorphism acceptable for characterization of these accessions. Totally
118 RAPD fragments were generated from 13 decamer primer and 64 of them were found polymorphic (54.2%). Mus and FCV showed
the smallest genetic distance among accessions cultivated in the eastern Anatolia. These results shows that the RAPD assay
is a powerful approach for identifying genetic and geographic polymorphism.
This article was submitted by the authors in English. 相似文献
750.
Ozturkcan SA Turhan K Turgut Z Karadayi M Gulluce M 《Journal of biochemical and molecular toxicology》2012,26(7):258-263
The aim of this study was to determine the antigenotoxic potential of two newly synthesized β-aminoketones against N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and 9-aminoacridine (9-AA)-induced mutagenesis. The mutant bacterial tester strains were MNNG-sensitive Escherichia coli WP2 uvrA and 9-AA-sensitive Salmonella typhimurium TA1537. Both test compounds showed significant antimutagenic activity at various tested concentrations. The inhibition rates ranged from 29.5% (compound 1: 2 mM/plate) to 47.5% (compound 2: 1.5 mM/plate) for MNNG and from 25.0% (compound 2: 1 mM/plate) to 52.1% (compound 2: 2.5 mM/plate) for 9-AA genotoxicity. Moreover, the mutagenicity of the test compounds was investigated by using the same strains. Neither test compound has mutagenic properties on the bacterial strains at the tested concentrations. Thus, the findings of the present study give valuable information about chemical prevention from MNNG and 9-AA genotoxicity by using synthetic β-aminoketones. 相似文献