全文获取类型
收费全文 | 662篇 |
免费 | 41篇 |
专业分类
703篇 |
出版年
2024年 | 3篇 |
2023年 | 4篇 |
2022年 | 26篇 |
2021年 | 28篇 |
2020年 | 29篇 |
2019年 | 82篇 |
2018年 | 36篇 |
2017年 | 28篇 |
2016年 | 29篇 |
2015年 | 29篇 |
2014年 | 44篇 |
2013年 | 77篇 |
2012年 | 57篇 |
2011年 | 60篇 |
2010年 | 32篇 |
2009年 | 30篇 |
2008年 | 24篇 |
2007年 | 18篇 |
2006年 | 19篇 |
2005年 | 8篇 |
2004年 | 5篇 |
2003年 | 5篇 |
2002年 | 7篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1993年 | 2篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1986年 | 1篇 |
1976年 | 1篇 |
1973年 | 2篇 |
排序方式: 共有703条查询结果,搜索用时 15 毫秒
31.
32.
Masoud Maleki Abdolali Shojaeiyan Sajad Rashidi Monfared 《Journal of Genetic Engineering and Biotechnology》2018,16(2):599-606
ISSR markers were applied to evaluate the genetic diversity and differentiation of 270 individuals of 27 Iranian C. melo landraces of various varietal groups include vars. inodorous, cantalupensis, reticulatus, ameri, dudaim. Genetic diversity among the studied genotypes obtained by GeneAlex analysis (H?=?0.08, I?=?0.12, Na?=?0.77, PPL?=?22.6%). Cluster analysis divided Iranian melon landraces into two main cluster. Non-sweet genotype (dudaim group) was well separated from sweet genotypes (inodorous, ameri, reticulatus, cantalupensis). The most similar genotypes were BANI and TONI (0.95) and the most dissimilar ones were GER and TS (0.58). AMOVA result showed that the percentage of genetic variation among and within Iranian melon is 69% and 31%, respectively. All landraces evaluated based on 10 morphological traits which revealed the diversity of melon varietal groups. Bayesian analysis assigned ten landraces to Pop 1, eight landraces to Pop 2 and nine melon landraces to Pop 3. Bayesian and UPGMA cluster analyses demonstrated the almost related results. Our results indicated that ISSR markers technique alongside polyacrylamide gel analysis could be helpful to discriminate varieties of melon. 相似文献
33.
Mina?AryaEmail authorView authors OrcID profile Ali?Akbar?Mirzaei Abdol?Mahmood?Davarpanah Seyed?Masoud?Barakati Hossein?Atashi Abas?Mohsenzadeh Kim?Bolton 《Journal of molecular modeling》2018,24(2):47
Catalytic combustion of hydrocarbons is an important technology to produce energy. Compared to conventional flame combustion, the catalyst enables this process to operate at lower temperatures; hence, reducing the energy required for efficient combustion. The reaction and activation energies of direct combustion of hydrocarbons (CH?→?C?+?H) on a series of metal surfaces were investigated using density functional theory (DFT). The data obtained for the Ag, Au, Al, Cu, Rh, Pt, and Pd surfaces were used to investigate the validity of the Brønsted-Evans-Polanyi (BEP) and transition state scaling (TSS) relations for this reaction on these surfaces. These relations were found to be valid (R2?=?0.94 for the BEP correlation and R2?=?1.0 for the TSS correlation) and were therefore used to estimate the energetics of the combustion reaction on Ni, Co, and Fe surfaces. It was found that the estimated transition state and activation energies (ETS?=??69.70 eV and Ea?=?1.20 eV for Ni, ETS?=??87.93 eV and Ea?=?1.08 eV for Co and ETS?=??92.45 eV and Ea?=?0.83 eV for Fe) are in agreement with those obtained by DFT calculations (ETS?=??69.98 eV and Ea?=?1.23 eV for Ni, ETS?=??87.88 eV and Ea?=?1.08 eV for Co and ETS?=??92.57 eV and Ea?=?0.79 eV for Fe). Therefore, these relations can be used to predict energetics of this reaction on these surfaces without doing the time consuming transition state calculations. Also, the calculations show that the activation barrier for CH dissociation decreases in the order Ag ? Au ? Al ? Cu ? Pt ? Pd ? Ni?>?Co?>?Rh?>?Fe. 相似文献
34.
35.
36.
37.
38.
Altering expression of cinnamic acid 4-hydroxylase in transgenic plants provides evidence for a feedback loop at the entry point into the phenylpropanoid pathway 总被引:14,自引:0,他引:14
Pharmacological evidence implicates trans-cinnamic acid as a feedback modulator of the expression and enzymatic activity of the first enzyme in the phenylpropanoid pathway, L-phenylalanine ammonia-lyase (PAL). To test this hypothesis independently of methods that utilize potentially non-specific inhibitors, we generated transgenic tobacco lines with altered activity levels of the second enzyme of the pathway, cinnamic acid 4-hydroxylase (C4H), by sense or antisense expression of an alfalfa C4H cDNA. PAL activity and levels of phenylpropanoid compounds were reduced in leaves and stems of plants in which C4H activity had been genetically down-regulated. However, C4H activity was not reduced in plants in which PAL activity had been down-regulated by gene silencing. In crosses between a tobacco line over-expressing PAL from a bean PAL transgene and a C4H antisense line, progeny populations harboring both the bean PAL sense and C4H antisense transgenes had significantly lower extractable PAL activity than progeny populations harboring the PAL transgene alone. Our data provide genetic evidence for a feedback loop at the entry point into the phenylpropanoid pathway that had previously been inferred from potentially artifactual pharmacological experiments. 相似文献
39.
Najmabadi H Motazacker MM Garshasbi M Kahrizi K Tzschach A Chen W Behjati F Hadavi V Nieh SE Abedini SS Vazifehmand R Firouzabadi SG Jamali P Falah M Seifati SM Grüters A Lenzner S Jensen LR Rüschendorf F Kuss AW Ropers HH 《Human genetics》2007,121(1):43-48
Autosomal recessive gene defects are arguably the most important, but least studied genetic causes of severe cognitive dysfunction.
Homozygosity mapping in 78 consanguineous Iranian families with nonsyndromic autosomal recessive mental retardation (NS-ARMR)
has enabled us to determine the chromosomal localization of at least 8 novel gene loci for this condition. Our data suggest
that in the Iranian population NS-ARMR is very heterogeneous, and they argue against the existence of frequent gene defects
that account for more than a few percent of the cases.
Mohammad Mahdi Motazacker and Masoud Garshasbi have contributed equally to this work. 相似文献
40.
Abedi-Ardekani B Kamangar F Sotoudeh M Villar S Islami F Aghcheli K Nasrollahzadeh D Taghavi N Dawsey SM Abnet CC Hewitt SM Fahimi S Saidi F Brennan P Boffetta P Malekzadeh R Hainaut P 《PloS one》2011,6(12):e29488