全文获取类型
收费全文 | 476篇 |
免费 | 27篇 |
国内免费 | 3篇 |
出版年
2023年 | 3篇 |
2022年 | 8篇 |
2021年 | 30篇 |
2020年 | 24篇 |
2019年 | 61篇 |
2018年 | 34篇 |
2017年 | 26篇 |
2016年 | 32篇 |
2015年 | 26篇 |
2014年 | 33篇 |
2013年 | 49篇 |
2012年 | 48篇 |
2011年 | 33篇 |
2010年 | 18篇 |
2009年 | 11篇 |
2008年 | 10篇 |
2007年 | 12篇 |
2006年 | 7篇 |
2005年 | 7篇 |
2004年 | 7篇 |
2003年 | 2篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有506条查询结果,搜索用时 15 毫秒
71.
The stochastic nature of biochemical networks 总被引:3,自引:0,他引:3
Cell behaviour and the cellular environment are stochastic. Phenotypes vary across isogenic populations and in individual cells over time. Here we will argue that to understand the abilities of cells we need to understand their stochastic nature. New experimental techniques allow gene expression to be followed in single cells over time and reveal stochastic bursts of both mRNA and protein synthesis in many different types of organisms. Stochasticity has been shown to be exploited by bacteria and viruses to decide between different behaviours. In fluctuating environments, cells that respond stochastically can out-compete those that sense environmental changes, and stochasticity may even have contributed to chromosomal gene order. We will focus on advances in modelling stochasticity, in understanding its effects on evolution and cellular design, and on means by which it may be exploited in biotechnology and medicine. 相似文献
72.
Heydar Valizadeh Habib Abbasipour Hassan Askary Vahid Reza Moniri 《Archives Of Phytopathology And Plant Protection》2013,46(10):1162-1169
Dericorys albidula Serville (Orthoptera: Dericorythidae) is a major pest of Haloxylon ammodendron and other saxaul plant species in the Qom province, Iran. Using fungal insecticides can be an alternative method for chemical insecticides. Effect of insecticide fungi, Metarhizium anisopliae var. acridum, on the various nymphs of D. albidula was studied in the field through 2005 and 2006. Fixed concentrations of fungi (106, 107, 108, 109, 1010 and 1013 spore mL?1) were prepared as gasoline formulation and were sprayed on the locusts on H. ammodendron trees, and mortality percentage was recorded 15 days after treatment. The results showed that various concentrations significantly affected on the second, third, fourth and fifth nymphal instars of D. albidula compared to control in 2006, although this effect was lower in 2005 on nymphs. Mortality of the highest concentration (1013 spore mL?1) was higher (17.6–24%) than other concentrations in all tests, but these values were not notable. The results of this study showed that using M. anisopliae var. acridum diluted in gasoline can be effective on nymphal instars of locust, D. albidula, in two continuous years. 相似文献
73.
Samane Mohammadi Hossein Aroiee Ali Tehranifar Vahid Jahanbakhsh 《Archives Of Phytopathology And Plant Protection》2013,46(13):1603-1610
The development of natural crop protection products as alternatives to the use of synthetic fungicides is currently popular. The aim of this study is to evaluate the antifungal effects of several essential oils against the fungal pathogens, Botrytis cinerea and Rhizopus stolonifer, under in vitro condition. Four essential oils (fennel, black caraway, peppermint and thyme) were each tested at five concentrations (0, 200, 400, 600 or 800 μl l?1). In vitro results showed that the essential oil of black caraway and fennel had the highest fungicidal effect against B. cinerea and R. stolonifer, respectively. The growth of B. cinerea was completely inhibited by the essential oil of black caraway at 400 μl l?1. Fennel oil perfectly inhibited growth of R. stolonifer fungus colonies at concentration higher than 600 μl L?1 in potato dextrose agar medium. Percentage of spores germination was the lowest in medium of Fennel and black caraway essential oils, and was the highest in Thyme ones. These results show that plant essential oils can have a strong effect on reducing post-harvest decay. These plant essential oils could provide an alternative to synthetic chemicals to control post-harvest phytopathogenic fungi on fruit. 相似文献
74.
Vahid Kia Maryam Sharif Beigli Vahedeh Hosseini Ameneh Koochaki Mahdi Paryan Samira Mohammadi-Yeganeh 《In vitro cellular & developmental biology. Animal》2018,54(9):621-628
Breast cancer is the first common cancer among women worldwide. One of the major signaling pathways playing a role in the onset and progression of this disease is PI3K/Akt/mTOR, which can be inhibited by PTEN. miRNAs are small non-coding molecules that regulate the expression of their targets by inhibition or suppression, and thus, their dysregulated expression results in the development of cancer. Using various software applications predicting miRNAs and evaluating GEO microarray data, miR-144 was selected as an inhibitor of PTEN. The expression of miR-144 and PTEN was evaluated in 18 triple negative breast cancer (TNBC) clinical samples and cell lines including 4T1, MDA-MB-231, MDA-MB-468, SK-BR-3, and MCF-7 in comparison with normal cells. PTEN and miR-144 expression analysis revealed their elevated expression in MCF-7 cells. MDA-MB-468, SK-BR-3, and MDA-MB-231 cells showed decreased levels of PTEN and increased levels of miR-144. In contrast, 4T1 cells had an increased expression of PTEN and decreased expression of miR-144. In clinical samples, miR-144 was up-regulated in 22% of the cases and PTEN was down-regulated in 78% of the cases. The results showed that the expression of PTEN and miR-144 was inversely correlated in metastatic breast cancer cell lines. However, in TNBC clinical samples, there was no correlation between the expression of miR-144 and PTEN. Literature shows that there are other influencing factors affecting the expression of miRNAs. Therefore, care should be taken in interpreting the results of gene expression studies and its relation with cancer diagnosis/prognosis. 相似文献
75.
Vahid Shirshahi Shadie Hatamie Seyed Nasrollah Tabatabaei Marzieh Salimi Reza Saber 《Plasmonics (Norwell, Mass.)》2018,13(5):1585-1594
In the present study, the effect of nanosized graphene oxide layer on thermal stability and biocompatibility of gold nanorods has been examined. The graphene oxide-wrapped gold nanorods were prepared by electrostatic interaction between negatively charged graphene oxide and positively charged nanorods. The resulting nanohybrids were then heated at different time intervals to 95 °C in a water bath to assess the effect of heat on the rods morphology. The structural changes in gold nanorods were monitored via UV-Vis spectroscopy measurements and transmission electron microscopy images. In similar experiments, the graphene oxide used to wrap gold nanorods was reduced by ascorbic acid in a 95 °C water bath. Our results indicate that while bare gold nanorods are highly vulnerable to elevated temperatures, graphene oxide and reduced graphene oxide-coated gold nanorods remain thermally stable with no structural changes. We also confirmed that the enhanced thermal stability is highly dependent on the concentration of deposited graphene oxide available on the surface of the gold nanorods. In addition, we performed an MTT (3-[4,5-dimethylthiazol-2yl]-2,5-diphenyltetrazoliumbromide) assay to make a comparison between the cytotoxicity of the nanohybrids and their primary building blocks on human dermal fibroblast cells as a normal cell line. We found evidence that graphene oxide can enhance the biocompatibility of the rods through covering toxic chemicals on the surface of them. 相似文献
76.
Molecular interactions of thymol with bovine serum albumin: Spectroscopic and molecular docking studies 下载免费PDF全文
Leila Roufegarinejad Ali Jahanban‐Esfahlan Sanaz Sajed‐Amin Vahid Panahi‐Azar Mahnaz Tabibiazar 《Journal of molecular recognition : JMR》2018,31(7)
Thymol is the main monoterpene phenol present in the essential oils which is used in the food industry as flavoring and preservative agent. In this study, the interaction of thymol with the concentration range of 1 to 6 μM and bovine serum albumin (BSA) at fixed concentration of 1 μM was investigated by fluorescence, UV‐vis, and molecular docking methods under physiological‐like condition. Fluorescence experiments were performed at 5 different temperatures, and the results showed that the fluorescence quenching of BSA by thymol was because of a static quenching mechanism. The obtained binding parameters, K, were in the order of 104 M?1, and the binding number, n, was approximately equal to unity indicating that there is 1 binding site for thymol on BSA. Calculated thermodynamic parameters for enthalpy (ΔH), entropy (ΔS), and Gibb's free energy (ΔG) showed that the reaction was spontaneous and hydrophobic interactions were the main forces in the binding of thymol to BSA. The results of UV‐vis spectroscopy and Arrhenius' theory showed the complex formation in the interaction of thymol and BSA. Negligible conformational changes in BSA by thymol were observed in fluorescence experiments, and the same results were also obtained from UV‐vis studies. Results of molecular docking indicated that the subdomain IA of BSA was the binding site for thymol. 相似文献
77.
It has been shown that penconazole (PEN) acts as an endogenous signal molecule responsible for inducing stress tolerance in plants. The effect of PEN (15?mg?l–1) and sodium chloride (0, 100, and 200 mM NaCl) on some biochemical and molecular responses of safflower was studied. Results revealed that chlorophylls and total soluble protein contents decreased under salinity, however total carotenoid, anthocyanin, flavonoid, and carbohydrate contents increased as well as SOS1 and NHX1 genes expression. The exogenous PEN had a positive effect on chlorophylls, carotenoid, anthocyanin, flavonoid, soluble protein and carbohydrate contents. In addition, RT-qPCR analysis showed that the exogenous PEN induced expression of SOS1 and NHX1 genes in both salt-treated and untreated plants. Our data indicate that PEN helps safflower plants to better cope with salt stress. The results can provide new insights to better realizing the responsible mechanisms to regulate salinity resistance in safflower. PEN can be considered in order to ameliorate salinity effects, due to the low price and their availability. 相似文献
78.
Jayanta Kumar Biswas Anurupa Banerjee Mahendra Kumar Rai Jörg Rinklebe Sabry M. Shaheen Santosh Kumar Sarkar Madhab Chandra Dash Anilava Kaviraj Uwe Langer Hocheol Song Meththika Vithanage Monojit Mondal Nabeel Khan Niazi 《Biodegradation》2018,29(4):323-337
The aim was to isolate, characterize, and explore potentials of gut bacteria from the earthworm (Metaphire posthuma) and imply these bacteria for remediation of Cu(II) and Zn(II). An extracellular polymeric substance (EPS) producing gut bacteria (Bacillus licheniformis strain KX657843) was isolated and identified based on 16S rRNA sequencing and phylogenetic analysis. The strain showed maximum tolerance of 8 and 6 mM for Cu(II) and Zn(II) respectively. It removed 34.5% of Cu(II) and 54.4% of Zn(II) at 25 mg L?1 after 72 and 96 h incubation respectively. The bacteria possessed a great potential to produce indole acetic acid (38.49 μg mL?1) at 5 mg mL?1 l-tryptophan following 12 days incubation. The sterilized seeds of mung beans (Vigna radiata) displayed greater germination and growth under bacterium enriched condition. We observed that the bacterial strain phosphate solubilization ability with a maximum of 204.2 mg L?1 in absence of Cu(II) and Zn(II). Endowed with biosurfactant property the bacterium exhibited 24% emulsification index. The bacterium offered significant potential of plant growth promotion, Cu(II) and Zn(II) removal, and as such this study is the first report on EPS producing B. licheniformis KX657843 from earthworm which can be applied as powerful tool in remediation programs of Cu(II) and Zn(II) contaminated sites. 相似文献
79.
DuBois Arthur B.; Kelley Patrick M.; Douglas James S.; Mohsenin Vahid 《Journal of applied physiology》1999,86(1):159-167
Different volumesof dead-space gas were collected and analyzed for nitric oxide (NO)content, either immediately after inspiration or after a period ofbreath holding on clean air or NO mixtures. This allowed calculation ofNO equilibrium, NO production, and NO absorption. In seven young,healthy, adult nonsmokers, the mean NO equilibrium values in parts perbillion (ppb) were 56 ± 11 (SE) in the trachea, 37 ± 6 in thebronchi, 21 ± 3 in the bronchioles, and 16 ± 2 in therespiratory bronchioles. At any given NO concentration, the NOabsorption rate (in nl/min) equaled the NO concentration (in ppb) timesA (the absorption coefficient inl/min). A values (in l/min) were 0.11 ± 0.01 in the trachea, 0.17 ± 0.04 in the bronchi, 0.66 ± 0.09 in the bronchioles, and 1.35 ± 0.32 in the respiratorybronchioles. NO equilibrium concentrations and production rates in one74-yr-old subject were three to five times as high as those found inthe young subjects. Mouth equilibrium NO concentrations were 3 and 6 parts per million in two subjects who had oral production rates of 6 and 23 nl/min, respectively. In conclusion, production and absorptionof NO occur throughout the first 450 ml of the airways. 相似文献
80.
Essam Abdel-Salam Shaalan Deon Vahid Canyon Reinhold Muller Mohamed Wagdy Faried Younes Hoda Abdel-Wahab Abdel-Hamid Mansour 《Journal of vector ecology》2007,32(1):16-21
A twelve-month survey for mosquito predators was conducted in Townsville, Queensland, Australia, which is located in the arid tropics. The survey revealed the presence of five predaceous insects but only Anisops sp. (backswimmers) and Diplonychus sp. were common. Predatorial capacity and factors influencing this capacity were then assessed for adult Anisops sp. and adult and nymph stages of Diplonychus sp. against Culex annulirostris mosquito immatures under laboratory conditions. Predatorial capacity bioassays showed that adult Diplonychus sp. preyed upon both larval and pupal stages of Cx. annulirostris quite successfully. Nymphs of Diplonychus sp. proved to be more successful with smaller prey immatures, and Anisops sp adults did not prey successfully on any prey pupae. Increasing the foraging area and introducing aquatic vegetation significantly reduced the predatorial capacity of Diplonychus sp. nymphs, while only vegetation and not foraging area had a significant effect on adult Diplonychus sp. predation capacity. Overall, adult Diplonychus sp. proved to be a more efficient predator than Anisops sp., and field trials are now recommended to further assess the potential of Diplonychus sp. as a biocontrol agent. 相似文献