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   4959篇
  免费   245篇
  国内免费   3篇
  2022年   28篇
  2021年   61篇
  2020年   28篇
  2019年   51篇
  2018年   72篇
  2017年   53篇
  2016年   91篇
  2015年   145篇
  2014年   178篇
  2013年   329篇
  2012年   333篇
  2011年   302篇
  2010年   199篇
  2009年   195篇
  2008年   316篇
  2007年   308篇
  2006年   318篇
  2005年   314篇
  2004年   314篇
  2003年   297篇
  2002年   273篇
  2001年   55篇
  2000年   67篇
  1999年   60篇
  1998年   64篇
  1997年   53篇
  1996年   46篇
  1995年   39篇
  1994年   37篇
  1993年   36篇
  1992年   45篇
  1991年   43篇
  1990年   41篇
  1989年   65篇
  1988年   40篇
  1987年   26篇
  1986年   35篇
  1985年   25篇
  1984年   30篇
  1983年   25篇
  1982年   23篇
  1981年   17篇
  1980年   15篇
  1979年   16篇
  1978年   15篇
  1977年   11篇
  1976年   17篇
  1975年   14篇
  1974年   8篇
  1973年   12篇
排序方式: 共有5207条查询结果,搜索用时 390 毫秒
911.
We have detected PCR products from Salmonella spp. and Influenza A virus using Zn finger protein Zif268 and Sp1, respectively. Previously, we demonstrated a novel method of rapid and specific detection of PCR products from Legionella pneumophila genome using Zn finger protein Sp1. In principle, this methodology might be applied to the detection of most bacteria and viruses using various Zn finger proteins. Here, to demonstrate the wider applicability of our method, we detected PCR products from Salmonella spp. and the Influenza A virus. BLAST data indicated the Zif268 and Sp1 recognition sequence were located on the gyrB gene of Salmonella spp. and the nucleoprotein gene of Influenza A virus, respectively. The PCR products from the oligonucleotide corresponding to the gyrB gene of Salmonella spp. or the nucleoprotein gene of the Influenza A virus could be specifically detected by ELISA or fluorescence depolarization measurement using Zif268 or Sp1. These results indicate the wide applicability of our novel methodology.  相似文献   
912.
913.
DNA fingerprinting analysis such as amplified ribosomal DNA restriction analysis (ARDRA), repetitive extragenic palindromic PCR (rep-PCR), ribosomal intergenic spacer analysis (RISA), and denaturing gradient gel electrophoresis (DGGE) are frequently used in various fields of microbiology. The major difficulty in DNA fingerprinting data analysis is the alignment of multiple peak sets. We report here an R program for a clustering-based peak alignment algorithm, and its application to analyze various DNA fingerprinting data, such as ARDRA, rep-PCR, RISA, and DGGE data. The results obtained by our clustering algorithm and by BioNumerics software showed high similarity. Since several R packages have been established to statistically analyze various biological data, the distance matrix obtained by our R program can be used for subsequent statistical analyses, some of which were not previously performed but are useful in DNA fingerprinting studies.  相似文献   
914.
We evaluated the efficacy of three SARS vaccine candidates in a murine SARS model utilizing low-virulence Pp and SARS-CoV coinfection. Vaccinated mice were protected from severe respiratory disease in parallel with a low virus titer in the lungs and a high neutralizing antibody titer in the plasma. Importantly, the administration of spike protein-specific neutralizing monoclonal antibody protected mice from the disease, indicating that the neutralization is sufficient for protection. Moreover, a high level of IL-6 and MCP-1 production, but not other 18 cytokines tested, on days 2 and 3 after SARS-CoV infection was closely linked to the virus replication and disease severity, suggesting the importance of these cytokines in the lung pathogenicity of SARS-CoV infection.  相似文献   
915.
We have developed a free‐energy function based on an all‐atom model for proteins. It comprises two components, the hydration entropy (HE) and the total dehydration penalty (TDP). Upon a transition to a more compact structure, the number of accessible configurations arising from the translational displacement of water molecules in the system increases, leading to a water‐entropy gain. To fully account for this effect, the HE is calculated using a statistical‐mechanical theory applied to a molecular model for water. The TDP corresponds to the sum of the hydration energy and the protein intramolecular energy when a fully extended structure, which possesses the maximum number of hydrogen bonds with water molecules and no intramolecular hydrogen bonds, is chosen as the standard one. When a donor and an acceptor (e.g., N and O, respectively) are buried in the interior after the break of hydrogen bonds with water molecules, if they form an intramolecular hydrogen bond, no penalty is imposed. When a donor or an acceptor is buried with no intramolecular hydrogen bond formed, an energetic penalty is imposed. We examine all the donors and acceptors for backbone‐backbone, backbone‐side chain, and side chain‐side chain intramolecular hydrogen bonds and calculate the TDP. Our free‐energy function has been tested for three different decoy sets. It is better than any other physics‐based or knowledge‐based potential function in terms of the accuracy in discriminating the native fold from misfolded decoys and the achievement of high Z‐scores. Proteins 2009. © 2009 Wiley‐Liss, Inc.  相似文献   
916.
The oxidative modification of proteins is believed to play a critical role in the etiology and/or progression of several diseases. α-Aminoadipic semialdehyde (AAS) and γ-glutamic semialdehyde (GGS) residues represent major oxidized amino acids generated in oxidized proteins. This paper describes a novel procedure for the specific and sensitive determination of AAS and GGS after their reductive amination with sodium cyanoborohydride and p-aminobenzoic acid, a fluorescence reagent, to their corresponding derivatives, followed by a high-performance liquid chromatography (HPLC) analysis. This fluorescent labeling of protein-associated aldehyde moieties is a simple and accurate technique that may be widely used to reveal increased levels of oxidatively modified proteins with reactive oxygen species during aging and disease.  相似文献   
917.
918.
In contrast to extensive studies on tocopherols, very little is understood about tocotrienols (T3). We evaluated the antitumor activities of gamma-T3 and delta-T3 in murine hepatoma MH134 cells in vitro and in vivo. We found that delta-T3 inhibited the growth of MH134 cells more strongly than gamma-T3 by inducing apoptosis. In C3H/HeN mice implanted with MH134, it was found that gamma-T3 and delta-T3 feeding significantly delayed tumor growth. On the other hand, both T3 had no significant effect on body weight, normal-tissue weight and immunoglobulin levels. Intriguingly, we found that T3 was detected in tumor, but not in normal tissues. These results, to our knowledge, are the first demonstration of specific accumulation of gamma-T3 and delta-T3 in tumors and suggest that T3 accumulation is critical for the antitumor activities of T3.  相似文献   
919.
The semi-pilot scale of continuous flow type hydrothermal reactor has been investigated to separate hemicellulose fraction from corncob. We obtained the effective recovery of hemicellulose using tubular type reactor at 200 °C for 10 min. From constituent sugar analysis of corncob, 82.2% of xylan fraction was recovered as mixture of xylose, xylooligosaccharides and higher-xylooligosaccharide which has more than DP 10. During purification of solubilized fraction by hydrothermal reaction such as ultrafiltration and ion exchange resin, higher-xylooligosaccharide was recovered as the precipitate. This precipitate was identified as non-blanched xylan fraction which has from DP 11 to DP 21 mainly. In this system, only a small amount of furfural has been generated. This tubular reactor has a characteristic controllability of thermal history, and seems to be effective for sugar recovery from soft biomass like corncob.  相似文献   
920.
Our previous study revealed that compound 1 (9-(4′-hydroxy-4-biphenyl)acetamido-9-deoxy-Neu5Gcα2-6GalOMP) has the most promising affinity for mCD22. Replacing the subterminal galactose residue of 1 with benzyl or biphenylmethyl as aglycone led to 38- and 20-fold higher potency, respectively. This discovery represents a new direction in inhibitor design suitable for pharmaceutical development.  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