全文获取类型
收费全文 | 1886篇 |
免费 | 149篇 |
国内免费 | 1篇 |
专业分类
2036篇 |
出版年
2023年 | 6篇 |
2022年 | 19篇 |
2021年 | 23篇 |
2020年 | 20篇 |
2019年 | 12篇 |
2018年 | 18篇 |
2017年 | 19篇 |
2016年 | 38篇 |
2015年 | 46篇 |
2014年 | 52篇 |
2013年 | 111篇 |
2012年 | 88篇 |
2011年 | 106篇 |
2010年 | 71篇 |
2009年 | 61篇 |
2008年 | 118篇 |
2007年 | 112篇 |
2006年 | 114篇 |
2005年 | 112篇 |
2004年 | 123篇 |
2003年 | 99篇 |
2002年 | 103篇 |
2001年 | 40篇 |
2000年 | 53篇 |
1999年 | 38篇 |
1998年 | 25篇 |
1997年 | 17篇 |
1996年 | 18篇 |
1995年 | 15篇 |
1994年 | 11篇 |
1993年 | 16篇 |
1992年 | 43篇 |
1991年 | 30篇 |
1990年 | 24篇 |
1989年 | 37篇 |
1988年 | 32篇 |
1987年 | 25篇 |
1986年 | 24篇 |
1985年 | 20篇 |
1984年 | 11篇 |
1983年 | 12篇 |
1982年 | 13篇 |
1981年 | 12篇 |
1980年 | 8篇 |
1979年 | 9篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1974年 | 5篇 |
1969年 | 3篇 |
1967年 | 3篇 |
排序方式: 共有2036条查询结果,搜索用时 0 毫秒
81.
Maki Yamamoto Hisayoshi Nozaki Yutaka Miyazawa Tomojiro Koide Shigeyuki Kawano 《Journal of phycology》2003,39(1):172-184
The cell division mechanisms of seven strains from six species of Nannochloris Naumann were analyzed and compared with those of three species of Chlorella Beijerinck and Trebouxia erici Ahmadjian using differential interference microscopy and fluorescence microscopy. Nannochloris bacillaris Naumann divides by binary fission and N. coccoides Naumann divides by budding. Distinct triangular spaces or mother cell walls were found in the dividing autosporangia of the other five strains from four species of Nannochloris, three species of Chlorella, and T. erici. In an attempt to infer an evolutionary relationship between nonautosporic and autosporic species of Nannochloris, we constructed a phylogenetic tree of the actin genes using seven strains from six species of Nannochloris, three species of Chlorella, and T. erici. Nannochloris species were polyphyletic in the Trebouxiophyceae group. Two nonautosporic species of N. bacillaris and N. coccoides were monophyletic and positioned distally. Moreover, to determine their phylogenetic position within the Trebouxiophyceae, we constructed phylogenetic tree of 18S rRNA genes adding other species of Trebouxiophyceae. Nannochloris species were polyphyletic in the Trebouxiophyceae and appeared in two different lineages, a Chlorella–Nannochloris group and a Trebouxia–Choricystis group. The nonautosporic species, N. bacillaris and N. coccoides, and three autosporic species of Nannochloris belonged to the Chlorella–Nannochloris group. Nannochloris bacillaris and N. coccoides were also monophyletic and positioned distally in the phylogenetic tree of 18S rRNA genes. These results suggest that autosporulation is the ancestral mode of cell division in Nannochloris and that nonautosporulative mechanisms, such as binary fission and budding, evolved secondarily. 相似文献
82.
83.
Deepak S Kottapalli K Rakwal R Oros G Rangappa K Iwahashi H Masuo Y Agrawal G 《Current Genomics》2007,8(4):234-251
Invention of polymerase chain reaction (PCR) technology by Kary Mullis in 1984 gave birth to real-time PCR. Real-time PCR - detection and expression analysis of gene(s) in real-time - has revolutionized the 21(st) century biological science due to its tremendous application in quantitative genotyping, genetic variation of inter and intra organisms, early diagnosis of disease, forensic, to name a few. We comprehensively review various aspects of real-time PCR, including technological refinement and application in all scientific fields ranging from medical to environmental issues, and to plant. 相似文献
84.
Recent advances in technologies such as DNA microarrays have provided an abundance of gene expression data on the genomic scale. One of the most important projects in the post-genome-era is the systemic identification of gene expression networks. However, inferring internal gene expression structure from experimentally observed time-series data are an inverse problem. We have therefore developed a system for inferring network candidates based on experimental observations. Moreover, we have proposed an analytical method for extracting common core binomial genetic interactions from various network candidates. Common core binomial genetic interactions are reliable interactions with a higher possibility of existence, and are important for understanding the dynamic behavior of gene expression networks. Here, we discuss an efficient method for inferring genetic interactions that combines a Step-by-step strategy (Y. Maki, Y. Takahashi, Y. Arikawa, S. Watanabe, K. Aoshima, Y. Eguchi, T. Ueda, S. Aburatani, S. Kuhara, M. Okamoto, An integrated comprehensive workbench for inferring genetic networks: Voyagene, Journal of Bioinformatics and Computational Biology 2(3) (2004) 533.) with an analysis method for extracting common core binomial genetic interactions. 相似文献
85.
Daichi Ogawara Taketo Muroya Kazumi Yamauchi Taka-aki Iwamoto Yoshihiko Yagi Yoshihiro Yamashita Shou Waga Masahiro Akiyama Hisaji Maki 《DNA Repair》2010,9(1):90-95
REV3 is the catalytic subunit of DNA polymerase ζ (pol ζ), which is responsible for the damage-induced mutagenesis that arises during error-prone translesion synthesis in eukaryotes. The related REV3L genes in human and mouse encode proteins of approximately 350 kDa, twice as large as yeast REV3, but full-length REV3L has not been identified in any vertebrate cell. We report that Xenopus laevis REV3L encodes a 352-kDa protein that has high overall amino acid sequence similarity to its mammalian counterparts, and, for the first time in a vertebrate species, we have detected putative REV3L polypeptides of 300 and 340 kDa in X. laevis oocytes. Only the 300-kDa form is stored in eggs, where its concentration of about 65 pM is much lower than those of other replication and repair proteins including the accessory pol ζ subunit REV7. In fertilized eggs, the levels of this polypeptide did not change until neurula; the larger 340-kDa form first appeared at stages after gastrula, suggesting a pattern of regulation during development. These observations indicate the existence of REV3L as a scarce protein, of approximately the full predicted size, whose level may impose severe constraints on the assembly of pol ζ in X. laevis. 相似文献
86.
87.
The total number of collembolans collected from the hyphal mat of the ectomycorrhizal fungus Sarcodon scabrosus was less than half of that collected from the adjacent non-mat soil. The same was true of all families of collembolans except
one, although not all differences were significant. The exception was the Hypogastruridae, with more individuals in the hyphal
mat on the sampling day in the fruiting season; these were also the most abundant collembolans on the fruiting bodies. These
results indicate that most collembolans avoid the hyphal mat of S. scabrosus in a Japanese red pine forest. 相似文献
88.
89.
Arisue N Maki Y Yoshida H Wada A Sánchez LB Müller M Hashimoto T 《Journal of molecular evolution》2004,59(1):59-71
The ribosomes of the amitochondriate but hydrogenosome-containing protist lineage, the trichomonads, have previously been reported to be prokaryotic or primitive eukaryotic, based on evidence that they have a 70S sedimentation coefficient and a small number of proteins, similar to prokaryotic ribosomes. In order to determine whether the components of the trichomonad ribosome indeed differ from those of typical eukaryotic ribosomes, the ribosome of a representative trichomonad, Trichomonas vaginalis, was characterized. The sedimentation coefficient of the T. vaginalis ribosome was smaller than that of Saccharomyces cerevisiae and larger than that of Escherichia coli. Based on two-dimensional PAGE analysis, the number of different ribosomal proteins was estimated to be approximately 80. This number is the same as those obtained for typical eukaryotes (approximately 80) but larger than that of E. coli (approximately 55). N-Terminal amino acid sequencing of 18 protein spots and the complete sequences of 4 ribosomal proteins as deduced from their genes revealed these sequences to display typical eukaryotic features. Phylogenetic analyses of the five ribosomal proteins currently available also clearly confirmed that the T. vaginalis sequences are positioned within a eukaryotic clade. Comparison of deduced secondary structure models of the small and large subunit rRNAs of T. vaginalis with those of other eukaryotes revealed that all helices commonly found in typical eukaryotes are present and conserved in T. vaginalis, while variable regions are shortened or lost. These lines of evidence demonstrate that the T. vaginalis ribosome has no prokaryotic or primitive eukaryotic features but is clearly a typical eukaryotic type. 相似文献
90.