首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   106篇
  免费   14篇
  国内免费   3篇
化学   47篇
力学   7篇
综合类   8篇
数学   30篇
物理学   31篇
  2023年   3篇
  2022年   4篇
  2021年   3篇
  2020年   4篇
  2019年   10篇
  2018年   6篇
  2017年   7篇
  2016年   6篇
  2015年   6篇
  2014年   5篇
  2013年   12篇
  2012年   3篇
  2011年   3篇
  2009年   5篇
  2008年   4篇
  2007年   5篇
  2006年   4篇
  2005年   5篇
  2004年   2篇
  2002年   3篇
  2001年   1篇
  1998年   1篇
  1994年   1篇
  1991年   1篇
  1989年   1篇
  1988年   2篇
  1985年   1篇
  1984年   1篇
  1980年   1篇
  1979年   1篇
  1978年   1篇
  1977年   2篇
  1976年   3篇
  1975年   1篇
  1974年   2篇
  1973年   2篇
  1962年   1篇
排序方式: 共有123条查询结果,搜索用时 10 毫秒
101.
The modeling system RAMS-CMAQ is applied in this paper to East Asia to simulate the temporo-spatial concentration distributions of atmospheric aerosols. For evaluating its performances, modeled concentrations of aerosols such as sulfate, nitrate, ammonium, black carbon and organic carbon were compared with observations obtained in East Asia on board of two aircrafts in the springtime of 2001. The comparison showed generally good agreement, and, in particular, that the modeling system captured most of the important observed features, including vertical gradients of the aerosols of the Asian outflow over the western Pacific. The evaluation results provide us with much confidence for further use of the modeling system to investigate the transport and transformation processes of atmospheric aerosols over East Asia and to assess their impacts on the Earth's radiation budget.  相似文献   
102.
Middle East respiratory syndrome coronavirus (MERS-CoV), belonging to the betacoronavirus genus can cause severe respiratory illnesses, accompanied by pneumonia, multiorgan failure, and ultimately death. CoVs have the ability to transgress species barriers and spread swiftly into new host species, with human-to-human transmission causing epidemic diseases. Despite the severe public health threat of MERS-CoV, there are currently no vaccines or drugs available for its treatment. MERS-CoV papain-like protease (PLpro) is a key enzyme that plays an important role in its replication. In the present study, we evaluated the inhibitory activities of doxorubicin (DOX) against the recombinant MERS-CoV PLpro by employing protease inhibition assays. Hydrolysis of fluorogenic peptide from the Z-RLRGG-AMC–peptide bond in the presence of DOX showed an IC50 value of 1.67 μM at 30 min. Subsequently, we confirmed the interaction between DOX and MERS-CoV PLpro by thermal shift assay (TSA), and DOX increased ΔTm by ~20 °C, clearly indicating a coherent interaction between the MERS-CoV PL protease and DOX. The binding site of DOX on MERS-CoV PLpro was assessed using docking techniques and molecular dynamic (MD) simulations. DOX bound to the thumb region of the catalytic domain of the MERS-CoV PLpro. MD simulation results showed flexible BL2 loops, as well as other potential residues, such as R231, R233, and G276 of MERS-CoV PLpro. Development of drug repurposing is a remarkable opportunity to quickly examine the efficacy of different aspects of treating various diseases. Protease inhibitors have been found to be effective against MERS-CoV to date, and numerous candidates are currently undergoing clinical trials to prove this. Our effort follows a in similar direction.  相似文献   
103.
Abstract

The German Environmental Specimen Bank (GESB) was established in 1985 as a permanent institution for the systematic collection, processing, characterization and storage of representative environmental samples from different ecosystems throughout Germany. Immediately after the reunification a special sampling campaign was performed in representative areas of the former GDR focusing on the assessment of the environmental pollution situation. These samples can be regarded as a basis for monitoring the development of spatial and temporal trends in Eastern Germany. Selected results about the determination of chlorinated hydrocarbons (CHC) in various bioindicators (earthworms, pigeon eggs, poplar leaves, pine shoots, breams) are presented. Particular emphasis is given to the comparsion of the CHC burden in East and West Germany with respect to different contamination sources.  相似文献   
104.
Lee HY  Yoo JE  Park MJ  Chung U  Kim CY  Shin KJ 《Electrophoresis》2006,27(22):4408-4418
The present study analyzed 21 coding region SNP markers and one deletion motif for the determination of East Asian mitochondrial DNA (mtDNA) haplogroups by designing three multiplex systems which apply single base extension methods. Using two multiplex systems, all 593 Korean mtDNAs were allocated into 15 haplogroups: M, D, D4, D5, G, M7, M8, M9, M10, M11, R, R9, B, A, and N9. As the D4 haplotypes occurred most frequently in Koreans, the third multiplex system was used to further define D4 subhaplogroups: D4a, D4b, D4e, D4g, D4h, and D4j. This method allowed the complementation of coding region information with control region mutation motifs and the resultant findings also suggest reliable control region mutation motifs for the assignment of East Asian mtDNA haplogroups. These three multiplex systems produce good results in degraded samples as they contain small PCR products (101-154 bp) for single base extension reactions. SNP scoring was performed in 101 old skeletal remains using these three systems to prove their utility in degraded samples. The sequence analysis of mtDNA control region with high incidence of haplogroup-specific mutations and the selective scoring of highly informative coding region SNPs using the three multiplex systems are useful tools for most applications involving East Asian mtDNA haplogroup determination and haplogroup-directed stringent quality control.  相似文献   
105.
We study the exact solutions of the Emden–Fowler equations and generalize the n = 1 and n = 5 Lane–Emden equations. We analyze the series approximations and show that explicit formulas can be written for new classes of equations. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
106.
In this paper we study the p‐Laplace Emden–Fowler equation with a radial and sign‐changing weight in the unit ball under the Dirichlet boundary condition. We show that if the weight function is negative in the unit ball except for a small neighborhood of the boundary and positive at somewhere in this neighborhood, then no least energy solution is radially symmetric. Therefore the equation has both a positive radial solution and a positive nonradial solution. Moreover, we prove in the one dimensional case that if the neighborhood is large, then a positive solution is unique.  相似文献   
107.
The study represents the first systematic risk assessment study in East Singhbhum district, Jharkhand, India for the safety of groundwater for drinking purpose with respect to metal(loid)s. The district is known for its mining and related activities. The results demonstrated that concentrations of the metal(loid)s showed significant spatial variation with Al, Mn, Fe, Ni and Zn exceeding the drinking water standards. Principal component analysis resulted in extraction of four factors explaining 76.3% of the data variability. The extracted principal components pointed towards both geogenic and anthropogenic activities governing the groundwater quality. Risk assessment was quantified by the hazard quotient (HQ) and cancer risk for both adult and child. The risk on human health posed by the metal(loid)s was found to be adverse for Mn with HQ > 1 for child. The chronic risks to the local population were largely contributed by Mn, Co and As. However, the carcinogenic risk for As was within the acceptable cancer risk value of 1 × 10?4. Considering the geometric mean of the metal(loid)s in the study area, the hazard index (HI) for adult was above unity. Considering all the locations, the HI varied from 0.23 to 13.03 and 0.20 to 11.15 for adult and child, respectively, suggesting that the groundwater is unsuitable for drinking without treatment at most of the locations.  相似文献   
108.
We compared genetic variations in the VP1 gene of foot-and-mouth disease viruses (FMDVs) isolated since 2000 from various region of the world. We analyzed relative synonymous codon usage (RSCU) and phylogenetic relationship between geographical regions, and calculated the genetic substitution patterns between Korean isolate and those from other countries. We calculated the ratios of synonymously substituted codons (SSC) to all observed substitutions and developed a new analytical parameter, EMC (the ratio of exact matching codons within each synonymous substitution group) to investigate more detailed substitution patterns within each synonymous codon group. We observed that FMDVs showed distinct RSCU patterns according to phylogenetic relationships in the same serotype (serotype O). Moreover, while the SSC and EMC values of FMDVs decreased according to phylogenetic distance, G + C composition at the third codon position was strictly conserved. Although there was little variation among the SSC values of 18 amino acids, more dynamic differences were observed in EMC values. The EMC values of 4- and 6-fold degenerate amino acids showed significantly lower values while most 2-fold degenerate amino acids showed no significant difference. Our findings suggest that different EMC patterns among the 18 amino acids might be an important factor in determining the direction of evolution in FMDV.  相似文献   
109.
A mild and convenient visible-light-promoted cross-dehydrogenative-coupling reaction between N-arylglycine esters and imidazo[1,2-a]pyridines for the construction of CC bond was developed. A range of N-arylglycine esters and imidazo[1,2-a]pyridines were able to undergo the CDC reaction readily to afford α-heteroaryl substituted α-amino acid derivatives in good to excellent yields. A tentative mechanism for the photoredox reaction was also proposed. Importantly, the use of copper(II) salt as the sole catalyst in this visible-light-promoted transformation makes this reaction sustainable and practical.  相似文献   
110.
The analysis of odour components in East Indian Sandalwood Oil (Santalum album L.) and in Patchouli Oil (Pogostemon cablin Benth.) based on GC-, GC-FTIR- and GC-MS-data resulted in the identification of-santalene,-santalal,-santalal, epi--santalal,-santalol,-santalol, (E)--santalol,-bergamotol and spirosantalol in Sandalwood Oil and of (–)-patchoulol,-guaiene,-patchoulene, seychellene,-bulnesene, norpatchoulenol and pogostol in Patchouli Oil as the most intense aroma compounds of these oils.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号