全文获取类型
收费全文 | 1998篇 |
免费 | 90篇 |
国内免费 | 1篇 |
专业分类
2089篇 |
出版年
2022年 | 9篇 |
2021年 | 16篇 |
2020年 | 9篇 |
2019年 | 9篇 |
2018年 | 26篇 |
2017年 | 24篇 |
2016年 | 30篇 |
2015年 | 65篇 |
2014年 | 71篇 |
2013年 | 122篇 |
2012年 | 115篇 |
2011年 | 128篇 |
2010年 | 72篇 |
2009年 | 82篇 |
2008年 | 139篇 |
2007年 | 132篇 |
2006年 | 114篇 |
2005年 | 124篇 |
2004年 | 130篇 |
2003年 | 132篇 |
2002年 | 144篇 |
2001年 | 25篇 |
2000年 | 7篇 |
1999年 | 29篇 |
1998年 | 33篇 |
1997年 | 25篇 |
1996年 | 12篇 |
1995年 | 22篇 |
1994年 | 19篇 |
1993年 | 18篇 |
1992年 | 24篇 |
1991年 | 14篇 |
1990年 | 9篇 |
1989年 | 15篇 |
1988年 | 18篇 |
1987年 | 5篇 |
1986年 | 6篇 |
1985年 | 13篇 |
1984年 | 17篇 |
1983年 | 9篇 |
1982年 | 13篇 |
1981年 | 13篇 |
1980年 | 7篇 |
1978年 | 3篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1972年 | 6篇 |
1971年 | 3篇 |
1970年 | 4篇 |
1962年 | 5篇 |
排序方式: 共有2089条查询结果,搜索用时 15 毫秒
81.
Watanabe M Sato M Kondo K Narikawa R Ikeuchi M 《Biochimica et biophysica acta》2012,1817(8):1428-1435
Phycobilisome (PBS) is a photosynthetic antenna supercomplex consisting of a central core subcomplex with several peripheral rods radiating from the core. Subunit structure of PBS was studied in a glaucocystophyte Cyanophora paradoxa strain NIES 547. Subunit composition of PBS was identified by N-terminal sequencing and genes for the subunits were determined by homology search of databases. They included rod linker proteins CpcK1 and CpcK2, rod-core linker proteins CpcG1 and CpcG2, and core linker proteins ApcC1 and ApcC2. Subfractionation by native polyacrylamide gel electrophoresis provided evidence for novel subcomplexes (ApcE/CpcK1/CpcG2/ApcA/ApcB/CpcD and ApcE/CpcK2/CpcG1/ApcA/ApcB), which connect rod and core subcomplexes. These skeleton-like structures may serve as a scaffold of the whole PBS assembly. Different roles of ApcC1 and ApcC2 were also suggested. Based on these findings, structural models for PBS were proposed. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial. 相似文献
82.
83.
We analyzed butterfly community composition using multivariate analyses. The results of principal components analysis showed that the butterfly community was composed mainly of two species groups. This species grouping was also supported by the results of the cluster analysis (unweighted pair‐group method using arithmetic average). Comparing the present results with species classification based on the generalist/specialist concept, the butterfly community was found to be composed of five species groups differing from each other in their ecological characteristics: a specialist group, two intermediate groups and two generalist groups. By comparison of their characteristics, it was suggested that, in the butterfly community, the positions of the specialist group and one of the generalist groups are the endpoints on the generalist/specialist selection spectrum, and the three other groups are positioned between these two extremes. The multivariate analyses showed that the species grouping with the generalist/specialist concept based only on voltinism and larval diet breadth was not sufficient to classify both intermediate and generalist groups, and also succeeded in extracting a typical generalist group from the butterfly community. From these results, we propose and recommend the synergetic application of the generalist/specialist concept and multivariate approaches to the detailed analysis and deeper understanding of community structure and composition. 相似文献
84.
Akio Shimizu Kagayaki Morishima Masahiro Kobayashi Masahiko Kunimoto Ichiro Nakayama 《Journal of applied phycology》2008,20(1):83-88
Conchospore germlings of Porphyra yezoensis were stained with a fluorescent dye for DNA and observed with confocal laser scanning microscopy (CLSM). Relative DNA values
of the germling nuclei were obtained by measuring fluorescence intensities of nuclear regions of the optically sliced specimens,
using the mean value of the smallest blade cells as a reference of the genomic n value. Such quantification revealed that the nuclear DNA amounts of the one-cell, two-cell, and four-cell-stage germlings
are approximately 4 × n, 2 × n, and n ∼2 × n values respectively; these values agreed well with the expected ones from the hypothesis that meiosis corresponds to the
first successive cell divisions after the conchospore germination. These results are consistent with a previous study on cytogenetic
analysis of the chimaera blade formation (Ohme and Miura 1988, Plant Sci 57:135–140) and not consistent with a recent microscopic study (Wang et al. 2006, Phycol Res 54:201–207) which proposed that the first meiotic division occurs at the conchospore formation and the second
division at the germination. 相似文献
85.
Mori M Sriwanthana B Wichukchinda N Boonthimat C Tsuchiya N Miura T Pathipvanich P Ariyoshi K Sawanpanyalert P 《PloS one》2011,6(8):e22680
Cytotoxic T Lymphocytes (CTLs) play a central role in controlling HIV-replication. Although numerous CTL epitopes have been described, most are in subtype B or C infection. Little is known about CTL responses in CRF01_AE infection. Gag CTL responses were investigated in a cohort of 137 treatment-naïve HIV-1 infected Thai patients with high CD4+ T cell counts, using gIFN Enzyme-Linked Immunospot (ELISpot) assays with 15-mer overlapping peptides (OLPs) derived from locally dominant CRF01_AE Gag sequences. 44 OLPs were recognized in 112 (81.8%) individuals. Both the breadth and magnitude of the CTL response, particularly against the p24 region, positively correlated with CD4+ T cell count and inversely correlated with HIV viral load. The breadth of OLP response was also associated with slower progression to antiretroviral therapy initiation. Statistical analysis and single peptide ELISpot assay identified at least 17 significant associations between reactive OLP and HLA in 12 OLP regions; 6 OLP-HLA associations (35.3%) were not compatible with previously reported CTL epitopes, suggesting that these contained new CTL Gag epitopes. A substantial proportion of CTL epitopes in CRF01_AE infection differ from subtype B or C. However, the pattern of protective CTL responses is similar; Gag CTL responses, particularly against p24, control viral replication and slow clinical progression. 相似文献
86.
Norihide Hinomoto Masahiko Muraji Takashi Noda Toru Shimizu Kenjiro Kawasaki 《Biological Control》2004,31(3):642
We developed multiplex polymerase chain reaction methods to identify five Orius (Heteroptera: Anthocoridae) species that occur commonly in Japan: Orius sauteri, Orius minutus, Orius strigicollis, Orius nagaii, and Orius tantillus. The method amplified internal transcribed spacer 1 of the nuclear ribosomal DNA by using five primers simultaneously and produced species-specific banding patterns upon agarose gel electrophoresis. Reliability of the method was tested for 350 individuals of 23 strains, and consistent results were obtained. Dichotomous keys are also provided for easy and quick species identification. 相似文献
87.
88.
Two formerly-uncharacterized subunits of 9 kDa and 14 kDa were found in spinach PSI complex. The 9 kDa subunit was released upon removal of antenna chlorophyll complex, whereas the 14 kDa subunit was tightly bound to the core complex. We determined the N-terminal amino acid sequence of the 9 kDa, and an internal sequence of the 14 kDa subunit after protease treatment, since the N-terminus of the latter protein was blocked. These partial sequences suggested that both subunits are new PSI components. 相似文献
89.
Akira Makino Anna Miyazaki Ayaka Tomoike Hiroyuki Kimura Kenji Arimitsu Masahiko Hirata Yoshiro Ohmomo Ryuichi Nishii Hidehiko Okazawa Yasushi Kiyono Masahiro Ono Hideo Saji 《Bioorganic & medicinal chemistry》2018,26(8):1609-1613
Tyrosine kinase inhibitors for epidermal growth factor receptor (EGFR-TKIs) are used as molecular targeted therapy for non-small cell lung cancer (NSCLC) patients. The therapy is applied to the patients having EGFR-primary L858R mutation, but drug tolerance caused by EGFR-secondary mutation is occurred within one and half years. For the non-invasive detection of the EGFR-TKIs treatment positive patients by positron emission tomograpy (PET) imagaing, fluorine-18 labeled thienopyrimidine derivative, [18F]FTP2 was newly synthesized. EGFR inhibition assay, cell uptake study, and blocking study indicated [18F]FTP2 binds with high and selective affinity for EGFR with L858R mutation, and not with L858R/T790M dual mutations. On animal PET study using tumor bearing mice, H3255 cells expressing L858R mutated EGFR was more clearly visualized than H1975 cells expressing L858R/T790M dual mutated EGFR. [18F]FTP2 has potential for detecting NSCLC which is susceptible to EGFR-TKI treatment. 相似文献
90.
Masahiko Ishida Hideo Nagayama Kensuke Shimura 《Bioscience, biotechnology, and biochemistry》2013,77(8):1881-1892
The biosynthetic pathway of vitamin B6 (abbreviated as Be) has been studied with the cell-suspension of B6-producing bacteria, Achromobacter cycloclastes A.M.S. 6201. The distribution of 14C in the Be molecule prepared with the cell-suspensions containing glycerol-1,3-14C, glycerol-2-14C or γ-aminobutyric acid-U-14C was investigated by using three novel degradation methods. The results showed that carbon skeletons of glycerol and γ-aminobutyric acid were used for the formation of the major part of B6 carbon skeleton respectively. The implication of these compounds as precursors of B6 was discussed. 相似文献