全文获取类型
收费全文 | 785篇 |
免费 | 35篇 |
专业分类
820篇 |
出版年
2024年 | 2篇 |
2023年 | 4篇 |
2022年 | 27篇 |
2021年 | 41篇 |
2020年 | 23篇 |
2019年 | 22篇 |
2018年 | 21篇 |
2017年 | 23篇 |
2016年 | 36篇 |
2015年 | 40篇 |
2014年 | 38篇 |
2013年 | 59篇 |
2012年 | 92篇 |
2011年 | 66篇 |
2010年 | 39篇 |
2009年 | 28篇 |
2008年 | 41篇 |
2007年 | 41篇 |
2006年 | 37篇 |
2005年 | 31篇 |
2004年 | 32篇 |
2003年 | 20篇 |
2002年 | 16篇 |
2001年 | 6篇 |
1999年 | 5篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1989年 | 3篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1979年 | 2篇 |
1954年 | 1篇 |
1952年 | 1篇 |
排序方式: 共有820条查询结果,搜索用时 15 毫秒
131.
Y. Bhargav Kumar Nandan Kumar Lijo John Hridoy Jyoti Mahanta S. Vaikundamani Selvaraman Nagamani G. Madhavi Sastry G. Narahari Sastry 《Proteins》2024,92(2):179-191
The cation-aromatic database (CAD) is a comprehensive repository of cation-aromatic motifs found in experimentally determined protein structures, first reported in 2007 [Proteins, 2007, 67, 1179]. The present article is an update of CAD that contains information of approximately 27.26 million cation-aromatic motifs. CAD uses three distance parameters (r, d1, and d2) to determine the position of the cation relative to the centroid of the aromatic residue and classifies the motifs as cation-π or cation-σ interactions. As of June 2023, about 193 936 protein structures were retrieved from Protein Data Bank, and this resulted in the identification of an impressive number of 27 255 817 cation-aromatic motifs. Among these motifs, spherical motifs constituted 94.09%, while cylindrical motifs made up the remaining 5.91%. When considering the interaction of metal ions with aromatic residues, 965 564 motifs are identified. Remarkably, 82.08% of these motifs involved the binding of metal ions to the amino acid HIS. Moreover, the analysis of binding preferences between cations and aromatic residues revealed that the HIS-HIS, PHE-ARG, and TRP-ARG pairs exhibited a preferential geometry. The motif pair HIS-HIS was the most prevalent, accounting for 19.87% of the total, closely followed by TYR-LYS at 10.17%. Conversely, the motif pair TRP-HIS had the lowest occurrence, representing only 4.20% of the total. The data generated help in revealing the characteristics and biological functions of cation-aromatic interactions in biological molecules. The updated version of CAD (Cation-Aromatic Database V2.0) can be accessed at https://acds.neist.res.in/cadv2 . 相似文献
132.
Jyoti Mareddy N. Suresh C. Ganesh Kumar Ravikumar Kapavarapu A. Jayasree Sarbani Pal 《Bioorganic & medicinal chemistry letters》2017,27(3):518-523
A new hybrid template has been designed by integrating the structural features of nimesulide and the 1,2,3-triazole moiety in a single molecular entity at the same time eliminating the problematic nitro group of nimesulide. The template has been used for the generation of a library of molecules as potential anticancer agents. A mild and greener CuAAC approach has been used to synthesize these compounds via the reaction of 4-azido derivative of nimesulide and terminal alkynes in water. Three of these compounds showed promising growth inhibition (IC50 ~6–10 μM) of A549, HepG2, HeLa and DU145 cancer cell lines but no significant effects on HEK293 cell line. They also inhibited PDE4B in vitro (60–70% at 10 μM) that was supported by the docking studies (PLP score 87–94) in silico. 相似文献
133.
Jyoti Kushwah Puneet Kumar Veena Garg Vishal Singh Somvanshi 《Indian journal of microbiology》2017,57(1):125-128
Photorhabdus is an insect-pathogenic Gram negative enterobacterium found in the gut of Heterorhabditis nematodes. Photorhabdus is highly virulent to insects, and can kill insects rapidly upon injection at very low concentrations of one to few cells. We characterized the virulence of Photorhabdus symbionts isolated from the Heterorhabditis nematodes collected from various parts of India by injecting different concentrations of bacterial cells into fourth instar larval stage of insect Galleria mellonella. Photorhabdus luminescens ssp. akhurstii strain IARI-SGMG3 from Meghalaya was identified as the most virulent of all the tested strains on the basis of LT50 and LC50 values. This study forms a basis for further investigations on the genetic basis of virulence in Photorhabdus bacteria. 相似文献
134.
135.
Exploring the Least Studied Australian Eucalypt Genera: Corymbia and Angophora for Phytochemicals with Anticancer Activity against Pancreatic Malignancies 下载免费PDF全文
Deep Jyoti Bhuyan Quan V. Vuong Danielle R. Bond Anita C. Chalmers Ian A. van Altena Michael C. Bowyer Christopher J. Scarlett 《化学与生物多样性》2017,14(3)
While the pharmacological and toxicological properties of eucalypts are well known in indigenous Australian medicinal practice, investigations of the bioactivity of eucalypt extracts against high mortality diseases such as pancreatic cancer in Western medicine have to date been limited, particularly amongst the genera Corymbia and Angophora. Four Angophora and Corymbia species were evaluated for their phytochemical profile and efficacy against both primary and secondary pancreatic cancer cell lines. The aqueous leaf extract of Angophora hispida exhibited statistically higher total phenolic content (107.85 ± 1.46 mg of gallic acid equiv. per g) and total flavonoid content (57.96 ± 1.93 mg rutin equiv. per g) and antioxidant capacity compared to the other tested eucalypts (P < 0.05). Both A. hispida and A. floribunda aqueous extracts showed statistically similar saponin contents. Angophora floribunda extract exerted significantly greater cell growth inhibition of 77.91 ± 4.93% followed by A. hispida with 62.04 ± 7.47% (P < 0.05) at 100 μg/ml in MIA PaCa‐2 cells with IC50 values of 75.58 and 87.28 μg/ml, respectively. More studies are required to isolate and identify the bioactive compounds from these two Angophora species and to determine their mode of action against pancreatic malignancies. 相似文献
136.
137.
Seasonal dynamics of zooplankton in a shallow eutrophic,man-made hyposaline lake in Delhi (India): role of environmental factors 总被引:1,自引:0,他引:1
Old Fort Lake, a small (1.6 ha), shallow, and recreational water body in Delhi (India) was studied through monthly surveys
in two consecutive years (January, 2000–December, 2001). Precipitation is the major source of water for this closed basin
lake. In addition, ground water is used for replenishing the lake regularly. This alkaline, hyposaline hard water lake contains
very high ionic concentration, especially of nitrates. Based on overall ionic composition, this lake can be categorized as
chloride–sulfate alkaline waters with the anion sequence dominated by SO4
2− > Cl− > HCO3
−, and the cations by Mg++ > Ca++. The overall seasonal variability in physicochemical profile was largely regulated by the annual cycle of evaporation and
precipitation, whereas the ground water largely influences its water quality. The lake exhibited phytoplankton-dominated turbid
state due to dominance of the blue green alga, Microcystis aeruginosa. The persistent cyanobacterial blooms and the elevated nutrient levels are indicative of the cultural eutrophication of the
lake. This study focuses on the relative importance of eutrophic vis-à-vis hyposaline conditions in determining the structure
and seasonal dynamics of zooplankton species assemblages. A total of 52 zooplankton species were recorded and rotifers dominated
the community structure qualitatively as well as quantitatively. The genus Brachionus comprised a significant component of zooplankton community with B. plicatilis as the most dominant species. The other common taxa were B. quadridentatus, B. angularis, Lecane grandis, L. thalera, L. punctata, Mesocyclops sp., and Alona rectangula. Multivariate data analysis techniques, Canonical Correspondence Analysis (CCA) along with Monte Carlo Permutation Tests
were used to determine the minimum number of environmental factors that could explain statistically significant (P < 0.05) proportions of variation in the species data. The significant variables selected by CCA were NH3–N followed by percent saturation of DO, COD, SS, BOD, NO2–N, rainfall, silicates, and PO4–P. The results indicate that the seasonal succession patterns of the zooplankton species were largely controlled by physicochemical
factors related directly or indirectly to the process of eutrophication, whereas hyposaline conditions in the lake determined
the characteristic species composition.
Guest Editors: J. John & B. Timms
Salt Lake Research: Biodiversity and Conservation—Selected papers from the 9th Conference of the International Society for
Salt Lake Research 相似文献
138.
Ram Shankar Upadhayaya Jaya Kishore Vandavasi Nageswara Rao Vasireddy Vivek Sharma Shailesh S. Dixit Jyoti Chattopadhyaya 《Bioorganic & medicinal chemistry》2009,17(7):2830-2841
We herein describe the synthesis and antimycobacterial activity of a series of 27 different derivatives of 3-benzyl-6-bromo-2-methoxy-quinolines and amides of 2-[(6-bromo-2-methoxy-quinolin-3-yl)-phenyl-methyl]-malonic acid monomethyl ester. The antimycobacterial activity of these compounds was evaluated in vitro against Mycobacterium tuberculosis H37Rv for nine consecutive days upon a fixed concentration (6.25 μg/mL) at day one in Bactec assay and compared to untreated TB cell culture as well as one with isoniazide treated counterpart, under identical experimental conditions. The compounds 3, 8, 17 and 18 have shown 92–100% growth inhibition of mycobacterial activity, with minimum inhibitory concentration (MIC) of 6.25 μg/mL. Based on our molecular modelling and docking studies on well-known diarylquinoline antitubercular drug R207910, the presence of phenyl, naphthyl and halogen moieties seem critical. Comparison of docking studies on different stereoisomers of R207910 as well as compounds from our data set, suggests importance of electrostatic interactions. Further structural analysis of docking studies on our compounds suggests attractive starting point to find new lead compounds with potential improvements. 相似文献
139.
HIF-1 α (hypoxia inducible factor-1 α isoform) has been exploited as a target in cancer therapeutics. HIF-1 α is the isoform-2 of HIF-1 α subunit. It is a 735 residues long protein modeled in this study. The HIF-1 α is absolutely critical for continued survival of cancer cells as it is involved in the activation of glycolysis and it helps an oxygen-starved cell convert sugar to energy without using oxygen. It also initiates angiogenesis to bring in a fresh oxygen supply. HIF-1 α operates only in presence of free radicals. In the present study, five antioxidants, namely lycopene, ascorbic acid, α-tocopherol, curcumin and curcumin dipiperoyl ester which are potent scavengers of reactive oxygen species (ROS) have been docked to HIF-1 α modeled protein in order to assess their binding and consequently, their inhibitory activity. The binding energy score has been found to be in the order, curumin dipiperoyl ester > lycopene > curcumin > tocopherol > ascorbic acid. However, subsequent experiments should be designed to validate these observations. 相似文献
140.
Vitamin E is a mixture of eight compounds α, β, γ, δ tocopherols and α, β, γ, δ tocotrienols. Their individual
role in cellular transport as antioxidants and in metabolic pathways has been highlighted in the present work. All the eight compounds have been docked with the respective
metabolizing enzymes (αtocopherol transfer protein (ATTP), αtocopherol associated protein (TAP), Pglycoprotein (Pgly) and human serum albumin (HSA)) to understand
molecular interactions for pharmacokinetics. These have been structurally aligned against the four human phospholipids in order to reveal their individual role in chylomicron
formation and hence the mechanism of cellular transport. The study of their binding with their metabolizing enzymes provides insight to the comparative antioxidant activity of each
of these isomers. 相似文献