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   7027篇
  免费   723篇
  国内免费   701篇
  2024年   15篇
  2023年   74篇
  2022年   100篇
  2021年   335篇
  2020年   247篇
  2019年   288篇
  2018年   284篇
  2017年   236篇
  2016年   293篇
  2015年   445篇
  2014年   539篇
  2013年   574篇
  2012年   639篇
  2011年   514篇
  2010年   327篇
  2009年   301篇
  2008年   369篇
  2007年   331篇
  2006年   308篇
  2005年   265篇
  2004年   268篇
  2003年   216篇
  2002年   253篇
  2001年   192篇
  2000年   163篇
  1999年   139篇
  1998年   124篇
  1997年   95篇
  1996年   80篇
  1995年   74篇
  1994年   63篇
  1993年   50篇
  1992年   51篇
  1991年   39篇
  1990年   26篇
  1989年   19篇
  1988年   26篇
  1987年   20篇
  1986年   11篇
  1985年   13篇
  1984年   29篇
  1983年   7篇
  1982年   6篇
  1981年   3篇
排序方式: 共有8451条查询结果,搜索用时 406 毫秒
991.
992.
YR Wu  LC Tan  X Fu  CM Chen  WL Au  L Chen  YC Chen  KM Prakash  Y Zheng  GJ Lee-Chen  Y Zhao  JS Zeng  EK Tan  Z Pei 《PloS one》2012,7(7):e36123
It has been suggested that a common LRRK2 polymorphic variant (A419V (rs34594498 C >T)) may be a risk factor among Asians (especially in Taiwan). In this study, we examined this variant in a larger and independent Taiwan cohort. We found the frequency of the variant (A419V) to be very rare in our Taiwan PD and controls (?0.6%). Further studies were conducted in two other Chinese populations (Singapore and China), comprising of a total of 3004 subjects including 1517 PD patients and 1487 control subjects. However, our multi-center Chinese study revealed that the frequency of the variant was rare (?0.4%) and was not associated with risk of PD, suggesting that the variant is not a major risk factor for PD among Chinese, at least in our study population.  相似文献   
993.
994.
Peng Z  Li LZ  Zhao MJ 《ZooKeys》2012,(184):57-66
Three new species of the genus Lathrobium Gravenhorst from Jiulongshan Natural Reserve, Zhejiang, East China, Lathrobium jiulongshanensesp. n., Lathrobium shenisp. n. and Lathrobium zhaotiexiongisp. n. are described and illustrated. A key to the Lathrobium species from Zhejiang Province is provided.  相似文献   
995.
Genome-Wide Analysis of bZIP-Encoding Genes in Maize   总被引:8,自引:0,他引:8  
In plants, basic leucine zipper (bZIP) proteins regulate numerous biological processes such as seed maturation, flower and vascular development, stress signalling and pathogen defence. We have carried out a genome-wide identification and analysis of 125 bZIP genes that exist in the maize genome, encoding 170 distinct bZIP proteins. This family can be divided into 11 groups according to the phylogenetic relationship among the maize bZIP proteins and those in Arabidopsis and rice. Six kinds of intron patterns (a–f) within the basic and hinge regions are defined. The additional conserved motifs have been identified and present the group specificity. Detailed three-dimensional structure analysis has been done to display the sequence conservation and potential distribution of the bZIP domain. Further, we predict the DNA-binding pattern and the dimerization property on the basis of the characteristic features in the basic and hinge regions and the leucine zipper, respectively, which supports our classification greatly and helps to classify 26 distinct subfamilies. The chromosome distribution and the genetic analysis reveal that 58 ZmbZIP genes are located in the segmental duplicate regions in the maize genome, suggesting that the segment chromosomal duplications contribute greatly to the expansion of the maize bZIP family. Across the 60 different developmental stages of 11 organs, three apparent clusters formed represent three kinds of different expression patterns among the ZmbZIP gene family in maize development. A similar but slightly different expression pattern of bZIPs in two inbred lines displays that 22 detected ZmbZIP genes might be involved in drought stress. Thirteen pairs and 143 pairs of ZmbZIP genes show strongly negative and positive correlations in the four distinct fungal infections, respectively, based on the expression profile and Pearson''s correlation coefficient analysis.  相似文献   
996.
997.
A prolyl endopeptidase (PEP) was purified to homogeneity from the skeletal muscle of common carp using a procedure involving ammonium sulfate fractionation and column chromatography involving DEAE-Sephacel, Phenyl-Sepharose, DEAE-Sepharose Fast Flow, and hydroxyapatite. The molecular weight of the PEP was 82 kDa as determined by SDS-PAGE. Using Suc-Gly-Pro-MCA as a substrate, the optimal pH and temperature of the purified enzyme were pH 6.0 and 35 °C, respectively, and the Km and kcat were 8.33 μM and 1.71 S?1, respectively. The activity of the PEP was inhibited by SUAM-14746, a specific inhibitor of prolyl endopeptidases, and was partially inhibited by the serine proteinase inhibitors PMSF and Pefabloc SC. According to peptide mass fingerprinting, 12 peptide fragments with a total of 134 amino acid residues were obtained, which were highly identical to prolyl endopeptidases from zebrafish (Danio rerio) and sponge (Amphimedon queenslandica), confirming the purified enzyme was a prolyl endopeptidase. Our present study for the first time reported the existence of a prolyl endopeptidase in fish muscle.  相似文献   
998.
Rice black-streaked dwarf virus (RBSDV) and stripe virus (RSV) are the two chronic viral diseases causing great damage to rice (Oryza sativa L.) production in China, and both are transmitted by the small brown planthopper (SBPH, Laodelphax striatellus Fallén). Quantitative trait loci (QTL) affecting field resistance to these two viral diseases were identified using QTL mapping software in a set of reciprocal introgression lines derived from the cross between Lemont and Teqing. A panel of 119 landraces was used for marker confirmation and allele mining. A total of 17 quantitative resistance loci (QRL) for the infection incidences of RBSDV and RSV were discovered and belong to 16 regions on all chromosomes except chromosome 12. Among them, 12 QRL were confirmed by association mapping, and many novel alleles at these loci were mined from the set of landraces. Only one region was found to be responsible for the genetic overlap between the field resistance against RBSDV and RSV, which was reported to be associated with SBPH resistance. The favorable alleles at the above novel and/or overlapping loci should be effective for marker-assisted selection breeding for resistance against the two diseases and the insect. Different strategies of varietal development and effective deployment against the two viral diseases are also discussed.  相似文献   
999.
1000.
Zhong X  Liu J  Lu F  Wang Y  Zhao Y  Dong S  Leng X  Jia J  Ren H  Xu C  Zhang W 《Cell biology international》2012,36(10):937-943
Nuclear Ca2+ plays a pivotal role in the regulation of gene expression. IP3 (inositol-1,4,5-trisphosphate) is an important regulator of nuclear Ca2+. We hypothesized that the CaR (calcium sensing receptor) stimulates nuclear Ca2+ release through IICR (IP3-induced calcium release) from perinuclear stores. Spontaneous Ca2+ oscillations and the spark frequency of nuclear Ca2+ were measured simultaneously in NRVMs (neonatal rat ventricular myocytes) using confocal imaging. CaR-induced nuclear Ca2+ release through IICR was abolished by inhibition of CaR and IP3Rs (IP3 receptors). However, no effect on the inhibition of RyRs (ryanodine receptors) was detected. The results suggest that CaR specifically modulates nuclear Ca2+ signalling through the IP3R pathway. Interestingly, nuclear Ca2+ was released from perinuclear stores by CaR activator-induced cardiomyocyte hypertrophy through the Ca2+-dependent phosphatase CaN (calcineurin)/NFAT (nuclear factor of activated T-cells) pathway. We have also demonstrated that the activation of the CaR increased the NRVM protein content, enlarged cell size and stimulated CaN expression and NFAT nuclear translocation in NRVMs. Thus, CaR enhances the nuclear Ca2+ transient in NRVMs by increasing fractional Ca2+ release from perinuclear stores, which is involved in cardiac hypertrophy through the CaN/NFAT pathway.  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