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   1427篇
  免费   69篇
  2023年   2篇
  2022年   8篇
  2021年   18篇
  2020年   12篇
  2019年   17篇
  2018年   19篇
  2017年   15篇
  2016年   40篇
  2015年   47篇
  2014年   51篇
  2013年   78篇
  2012年   98篇
  2011年   83篇
  2010年   64篇
  2009年   56篇
  2008年   90篇
  2007年   111篇
  2006年   76篇
  2005年   120篇
  2004年   98篇
  2003年   87篇
  2002年   84篇
  2001年   13篇
  2000年   9篇
  1999年   12篇
  1998年   22篇
  1997年   17篇
  1996年   20篇
  1995年   15篇
  1994年   19篇
  1993年   14篇
  1992年   9篇
  1991年   7篇
  1990年   5篇
  1989年   8篇
  1988年   3篇
  1987年   1篇
  1986年   3篇
  1985年   7篇
  1984年   6篇
  1983年   7篇
  1982年   5篇
  1981年   4篇
  1980年   3篇
  1978年   3篇
  1977年   3篇
  1976年   2篇
  1975年   1篇
  1974年   2篇
  1971年   2篇
排序方式: 共有1496条查询结果,搜索用时 0 毫秒
951.
Species-specific detection and quantification methods for barnacle larvae using quantitative real-time polymerase chain reaction (qPCR) were developed. Species-specific primers for qPCR were designed for 13 barnacle species in the mitochondrial 12S ribosomal RNA gene region. Primer specificity was examined by PCR using template DNA extracted from each of the 13 barnacle species, other unidentified barnacle species, and field collected zooplankton samples. The resulting PCR products comprised single bands following agarose gel electrophoresis when the templates corresponded to primers. The amplifications were highly species-specific even for the field plankton samples. The field plankton samples were subjected to qPCR assay. The calculated DNA contents for each barnacle species were closely correlated with the number of larvae measured by microscopic examination. The method could be applied to quantify barnacle larvae in natural plankton samples.  相似文献   
952.
Antigen-specific CD8+ T-lymphocytes (cytotoxic T-lymphocytes: CTL), as well as CD4+ T-lymphocytes (helper T-lymphocytes: Th), simultaneously play an important role in the elimination of intracellular bacteria such as Mycobacterium tuberculosis and Listeria monocytogenes. Administration of T-cell epitope short peptide needs large numbers of peptides for effective vaccination due to its easily degradable nature in vivo. In this respect, biocompatible and biodegradable microparticles combined with CTL/Th-hybrid epitope long peptide (long peptide) have been used to diminish the degradation of loaded peptide. The aim of this study is to develop a novel T cell-oriented vaccine against intracellular bacteria that is composed of long peptide and poly (lactic-co-glycolic acid) (PLGA) microparticles. Mouse bone marrow-derived dendritic cells (BMDCs) were loaded with L. monocytogenes listeriolysin O (LLO)-derived or ovalbumin (OVA)-derived long peptide/PLGA or other comparative antigens. The antigen-loaded BMDCs were injected subcutaneously into the flank of mice twice, and then, the spleens were collected and lymphocyte proliferation and interferon-γ production were evaluated. The median diameter of the PLGA spheres was 1.38 μm. Both LLO- and OVA-long peptide/PLGA showed significantly more robust CTL and Th proliferations with higher interferon-γ production than the long peptide alone or CTL and Th short peptides/PLGA vaccination. Furthermore, the LLO-long peptide/PLGA vaccination showed a significantly lower bacterial burden in spleens compared with the long peptide alone or the CTL and Th short peptides/PLGA vaccination after the challenge of lethal amounts of L. monocytogenes. These results suggest that the novel vaccine taking advantages of CTL/Th-hybrid epitope long peptide and PLGA microparticle is effective for protection against intracellular bacteria.  相似文献   
953.
The larvae of Japanese rhinoceros beetle, Trypoxylus dichotomus, feed on dead plant material in forest soils that are derived from fallen leaves broken down by basidiomycete fungi. Our previous work provided an understanding of the degradation of polysaccharides in dead plant material by T. dichotomus larvae and reported the complexity of the physicochemical and biochemical environment of the larval gut. Here, we examined ten divisions of the digestive tract of T. dichotomus larvae for physicochemical and biochemical conditions to elucidate site‐specifically functional properties along the tract. The distribution of potassium ions, pH, and acetic acid differed markedly along the length of the digestive tract with the potassium ion concentration profile closely reflecting that of pH along the length of the digestive tract. Distinct physicochemical environments were maintained in the digestive tract along with site‐specific polysaccharide degradation. Based on these findings, we suggest that there are metabolic relationships between the activities of the enzymes involved in polysaccharide degradation, the presence of intermediate metabolites and location along the digestive tract. Furthermore, we revealed that the anterior region of the gut plays an important role in the degradation of polysaccharides in the digestive tract of T. dichotomus larvae.  相似文献   
954.
Fostriecin is a phosphate monoester with excellent antitumor activity against mouse leukemia, and it is a potent inhibitor of protein phosphatase (PP) 2A. This compound has been predicted to covalently bind to the Cys269 residue of the PP2A catalytic subunit (PP2Ac) at the α,β-unsaturated lactone via a conjugate addition reaction. However, this binding has not yet been experimentally proven. To confirm such binding, we synthesized biotin-labeled fostriecin (bio-Fos), which has an inhibitory activity against the proliferation of mouse leukemia cells. We showed that fostriecin directly binds to PP2Ac in HeLa S3 cells by pull-down assays using bio-Fos. Moreover, we directly demonstrated that fostriecin covalently binds to the Cys269 residue of PP2Ac by matrix assisted laser desorption/ionization time-of-flight mass spectrometry analysis. From these results, the inhibitory mechanism of fostriecin on PP2A activity is discussed.  相似文献   
955.
956.
A novel acriflavine-sensitive mutant was isolated. The mutation was referred to as acrB1 and was demonstrated to be located at min 82.  相似文献   
957.
958.
959.
We have reported the antiallergic activities of the immunostimulatory oligodeoxynucleotide (ODN) BL07S, identified from genomic DNA of Bifidobacterium longum BB536 from in vitro and in vivo studies. The present study evaluated the efficiency of ODN BL07S in preventing allergic responses by oral administration. Oral administration of BL07S suppressed serum ovalbumin (OVA)-specific immunoglobulin (Ig) E levels and improved the OVA-specific IgG2a/IgG1 ratio. ODN BL07S increased Th1 cytokine and decreased Th2 cytokine production in splenocytes. These results suggest that immunostimulatory ODNs are potentially associated with the antiallergic effects of probiotics.  相似文献   
960.
In general, phototropic responses in land plants are induced by blue light and mediated by blue light receptor phototropins. In many cryptogam plants including the fern Adiantum capillus-veneris, however, red as well as blue light effectively induces a positive phototropic response in protonemal cells. In A. capillus-veneris, the red light effect on the tropistic response is mediated by phytochrome 3 (phy3), a chimeric photoreceptor of phytochrome and full-length phototropin. Here, we report red and blue light-induced negative phototropism in A. capillus-veneris rhizoid cells. Mutants deficient for phy3 lacked red light-induced negative phototropism, indicating that under red light, phy3 mediates negative phototropism in rhizoid cells, contrasting with its role in regulating positive phototropism in protonemal cells. Mutants for phy3 were also partially deficient in rhizoid blue light-induced negative phototropism, suggesting that phy3, in conjunction with phototropins, redundantly mediates the blue light response.  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