全文获取类型
收费全文 | 1875篇 |
免费 | 97篇 |
国内免费 | 2篇 |
专业分类
1974篇 |
出版年
2022年 | 10篇 |
2021年 | 20篇 |
2020年 | 12篇 |
2019年 | 16篇 |
2018年 | 22篇 |
2017年 | 18篇 |
2016年 | 47篇 |
2015年 | 55篇 |
2014年 | 70篇 |
2013年 | 131篇 |
2012年 | 92篇 |
2011年 | 84篇 |
2010年 | 63篇 |
2009年 | 62篇 |
2008年 | 97篇 |
2007年 | 89篇 |
2006年 | 94篇 |
2005年 | 81篇 |
2004年 | 87篇 |
2003年 | 86篇 |
2002年 | 99篇 |
2001年 | 27篇 |
2000年 | 42篇 |
1999年 | 35篇 |
1998年 | 30篇 |
1997年 | 21篇 |
1996年 | 16篇 |
1995年 | 24篇 |
1994年 | 24篇 |
1993年 | 22篇 |
1992年 | 31篇 |
1991年 | 31篇 |
1990年 | 33篇 |
1989年 | 39篇 |
1988年 | 22篇 |
1987年 | 27篇 |
1986年 | 22篇 |
1985年 | 15篇 |
1984年 | 14篇 |
1983年 | 16篇 |
1982年 | 11篇 |
1981年 | 22篇 |
1980年 | 19篇 |
1979年 | 12篇 |
1978年 | 11篇 |
1977年 | 11篇 |
1976年 | 12篇 |
1975年 | 10篇 |
1974年 | 12篇 |
1973年 | 7篇 |
排序方式: 共有1974条查询结果,搜索用时 0 毫秒
71.
Toshimichi Tsuboi Chihiro Sekijo Osamu Shoji 《Bioscience, biotechnology, and biochemistry》2013,77(12):1238-1246
The utilization of hydrocarbons by microorganisms was studied in many fields, but the production of biotin vitamers by hydrocarbon-utilizing bacteria has never been reported.We have screened many hydrocarbon-utilizing bacteria which produce biotin vitamers in the culture broth. The effects of cultural conditions on biotin vitamers production by strain 5–2, tentatively assigned to the genus Pseudomonas, were studied.More than 98% of biotin vitamers produced from hydrocarbons by strain 5–2 was chromatographically determined as desthiobiotin. As nitrogen source, natural nutrients were more effective than inorganic nitrogen sources. The production of biotin vitamers was increased under the condition of good aeration. Exogenous pimelic or azelaic acid enhanced biotin vitamers production by strain 5–2.The production of biotin vitamers from n-alkanes, n-alkenes or glucose by an isolated bacterium, strain 5-2, tentatively assigned to the genus Pseudomonas, was investigated. Among these carbon sources, n-undecane was the most excellent for biotin vitamers production.The biosynthetic pathway of biotin vitamers, especially desthiobiotin, from n-undecane was also studied. It was found by thin-layer and gas-liquid chromatographical methods that pimelic and azelaic acids were the main acid components in n-undecane culture.This result, together with previously reported enhancement of biotin vitamers production by these acids, suggests that pimelic and azelaic acids may be the intermediates of biotin vitamers biosynthesis from n-undecane. 相似文献
72.
Fumio Okada Tadakazu Takeo Shoji Okada Osamu Tamemasa 《Bioscience, biotechnology, and biochemistry》2013,77(5):791-794
Theaflavins, the oxidized products formed from tea leaf catechins during black tea fermentation, showed an antiviral activity on TMV. From the survey of the interactions of theaflavins with RNA and its related substances, it was presumed that theaflavins disturbed the replication cycle of TMV through binding to TMV-RNA. 相似文献
73.
74.
Shoji Kawamura 《Genes & genomics.》2016,38(9):779-791
Color provides a reliable cue for object detection and identification during various behaviors such as foraging, mate choice, predator avoidance and navigation. The total number of colors that a visual system can discriminate is largely dependent on the number of different spectral types of cone opsins present in the retina and the spectral separations among them. Thus, opsins provide an excellent model system to study evolutionary interconnections at the genetic, phenotypic and behavioral levels. Primates have evolved a unique ability for three-dimensional color vision (trichromacy) from the two-dimensional color vision (dichromacy) present in the majority of other mammals. This was accomplished via allelic differentiation (e.g. most New World monkeys) or gene duplication (e.g. Old World primates) of the middle to long-wavelength sensitive (M/LWS, or red–green) opsin gene. However, questions remain regarding the behavioral adaptations of primate trichromacy. Allelic differentiation of the M/LWS opsins results in extensive color vision variability in New World monkeys, where trichromats and dichromats are found in the same breeding population, enabling us to directly compare visual performances among different color vision phenotypes. Thus, New World monkeys can serve as an excellent model to understand and evaluate the adaptive significance of primate trichromacy in a behavioral context. I shall summarize recent findings on color vision evolution in primates and introduce our genetic and behavioral study of vision-behavior interrelationships in free-ranging sympatric capuchin and spider monkey populations in Costa Rica. 相似文献
75.
Epigenetic mechanisms such as DNA methylation or histone modifications are essential for the regulation of gene expression and development of tissues. Alteration of epigenetic modifications can be used as an epigenetic biomarker for diagnosis and as promising targets for epigenetic therapy. A recent study explored cancer-cell specific epigenetic biomarkers by examining different types of epigenetic modifications simultaneously. However, it was based on microarrays and reported biomarkers that were also present in normal cells at a low frequency. Here, we first analyzed multi-omics data (including ChIP-Seq data of six types of histone modifications: H3K27ac, H3K4me1, H3K9me3, H3K36me3, H3K27me3, and H3K4me3) obtained from 26 lung adenocarcinoma cell lines and a normal cell line. We identified six genes with both H3K27ac and H3K4me3 histone modifications in their promoter regions, which were not present in the normal cell line, but present in ≥85% (22 out of 26) and ≤96% (25 out of 26) of the lung adenocarcinoma cell lines. Of these genes, NUP210 (encoding a main component of the nuclear pore complex) was the only gene in which the two modifications were not detected in another normal cell line. RNA-Seq analysis revealed that NUP210 was aberrantly overexpressed among the 26 lung adenocarcinoma cell lines, although the frequency of NUP210 overexpression was lower (19.3%) in 57 lung adenocarcinoma tissue samples studied and stored in another database. This study provides a basis to discover epigenetic biomarkers highly specific to a certain cancer, based on multi-omics data at the cell population level. 相似文献
76.
Hiroshi Furukawa Shomi Oka Aya Kawasaki Kota Shimada Shoji Sugii Takashi Matsushita Atsushi Hashimoto Akiko Komiya Naoshi Fukui Kouji Kobayashi Atsumu Osada Atsushi Ihata Yuya Kondo Tatsuo Nagai Keigo Setoguchi Akiko Okamoto Akira Okamoto Noriyuki Chiba Eiichi Suematsu Hajime Kono Masao Katayama Shunsei Hirohata Takayuki Sumida Kiyoshi Migita Minoru Hasegawa Manabu Fujimoto Shinichi Sato Shouhei Nagaoka Kazuhiko Takehara Shigeto Tohma Naoyuki Tsuchiya 《PloS one》2016,11(4)
ObjectiveSeveral studies on associations between human leukocyte antigen (HLA) allele frequencies and susceptibility to systemic sclerosis (SSc) have been reported. Anti-centromere antibodies (ACA) and anti-topoisomerase I antibodies (ATA) are found in SSc patients. Here, we sought to identify HLA alleles associated with SSc in Japanese, and explored their associations with SSc phenotypes including the presence of autoantibodies.MethodsAssociations of HLA-DRB1, DQB1, and DPB1 were analyzed in 463 Japanese SSc patients and 413 controls.ResultsWe found that DRB1*13:02 (P = 0.0011, Pc = 0.0319, odds ratio [OR] 0.46, 95% confidence interval [CI] 0.29–0.73), DRB1*14:06 (P = 6.60X10-5, Pc = 0.0020, OR 0.05, 95%CI 0.01–0.41), DQB1*03:01 (P = 0.0009, Pc = 0.0150, OR 0.56, 95%CI 0.40–0.79), and DPB1*02:01 (P = 5.16X10-6, Pc = 8.77X10-5, OR 0.52, 95%CI 0.39–0.69) were protectively associated with SSc. In addition, these four alleles seemed to be independently associated with the protection against the susceptibility of SSc. On the other hand, we could not find predisposing alleles for overall SSc. With respect to SSc subsets, a tendency for these four alleles to be protectively associated was observed. However, there was a significant association between DRB1*01:01, DRB1*10:01, DQB1*05:01, and DPB1*04:02 and the susceptibility to SSc with ACA. On the other hand, the presence of DRB1*15:02, DQB1*06:01, DPB1*03:01, and DPB1*09:01 was associated with SSc with ATA.ConclusionThus, the present study has identified protective associations of the four HLA class II alleles with overall Japanese SSc and predisposing associations of HLA class II alleles with Japanese SSc subsets. 相似文献
77.
78.
Isoo N Sato C Miyashita H Shinohara M Takasugi N Morohashi Y Tsuji S Tomita T Iwatsubo T 《The Journal of biological chemistry》2007,282(17):12388-12396
gamma-Secretase is an atypical aspartyl protease that cleaves amyloid beta-precursor protein to generate Abeta peptides that are causative for Alzheimer disease. gamma-Secretase is a multimeric membrane protein complex composed of presenilin (PS), nicastrin, Aph-1, and Pen-2. Pen-2 directly binds to transmembrane domain 4 of PS and confers proteolytic activity on gamma-secretase, although the mechanism of activation and its role in catalysis remain unknown. Here we show that an addition of amino acid residues to the N terminus of Pen-2 specifically increases the generation of Abeta42, the longer and more aggregable species of Abeta. The effect of the N-terminal elongation of Pen-2 on Abeta42 generation was independent of the amino acid sequences, the expression system and the presenilin species. In vitro gamma-secretase assay revealed that Pen-2 directly affects the Abeta42-generating activity of gamma-secretase. The elongation of Pen-2 N terminus caused a reduction in the water accessibility of the luminal side of the catalytic pore of PS1 in a similar manner to that caused by an Abeta42-raising gamma-secretase modulator, fenofibrate, as determined by substituted cysteine accessibility method. These data suggest a unique mechanism of Abeta42 overproduction associated with structural changes in the catalytic pore of presenilins caused commonly by the N-terminal elongation of Pen-2 and fenofibrate. 相似文献
79.
Yoshiya Moriguchi Motonari Maeda Tetsuya Igarashi Toshio Ishikawa Masayasu Shoji Chiharu Kubo Gen Komaki 《BioPsychoSocial medicine》2007,1(1):1-15
Background
The construct validity of alexithymia and its assessment using the 20-item Toronto Alexithymia Scale (TAS-20) in Japan is unknown. Low reliability has been found for the third factor of the TAS-20 in some cultures, and the factor structure for psychosomatic disorder patients has not been adequately investigated. Although alexithymia most likely has certain developmental aspects, this has infrequently been investigated. 相似文献80.
Marko-Varga G Ogiwara A Nishimura T Kawamura T Fujii K Kawakami T Kyono Y Tu HK Anyoji H Kanazawa M Akimoto S Hirano T Tsuboi M Nishio K Hada S Jiang H Fukuoka M Nakata K Nishiwaki Y Kunito H Peers IS Harbron CG South MC Higenbottam T Nyberg F Kudoh S Kato H 《Journal of proteome research》2007,6(8):2925-2935
Personalized medicine allows the selection of treatments best suited to an individual patient and disease phenotype. To implement personalized medicine, effective tests predictive of response to treatment or susceptibility to adverse events are needed, and to develop a personalized medicine test, both high quality samples and reliable data are required. We review key features of state-of-the-art proteomic profiling and introduce further analytic developments to build a proteomic toolkit for use in personalized medicine approaches. The combination of novel analytical approaches in proteomic data generation, alignment and comparison permit translation of identified biomarkers into practical assays. We further propose an expanded statistical analysis to understand the sources of variability between individuals in terms of both protein expression and clinical variables and utilize this understanding in a predictive test. 相似文献