全文获取类型
收费全文 | 2755篇 |
免费 | 205篇 |
专业分类
2960篇 |
出版年
2022年 | 18篇 |
2021年 | 33篇 |
2020年 | 16篇 |
2019年 | 33篇 |
2018年 | 32篇 |
2017年 | 24篇 |
2016年 | 39篇 |
2015年 | 77篇 |
2014年 | 83篇 |
2013年 | 149篇 |
2012年 | 113篇 |
2011年 | 135篇 |
2010年 | 98篇 |
2009年 | 79篇 |
2008年 | 135篇 |
2007年 | 136篇 |
2006年 | 120篇 |
2005年 | 112篇 |
2004年 | 115篇 |
2003年 | 119篇 |
2002年 | 121篇 |
2001年 | 111篇 |
2000年 | 138篇 |
1999年 | 89篇 |
1998年 | 27篇 |
1997年 | 27篇 |
1996年 | 39篇 |
1995年 | 25篇 |
1994年 | 32篇 |
1993年 | 30篇 |
1992年 | 66篇 |
1991年 | 68篇 |
1990年 | 52篇 |
1989年 | 41篇 |
1988年 | 44篇 |
1987年 | 34篇 |
1986年 | 37篇 |
1985年 | 39篇 |
1984年 | 33篇 |
1983年 | 24篇 |
1982年 | 19篇 |
1981年 | 24篇 |
1980年 | 17篇 |
1979年 | 15篇 |
1978年 | 23篇 |
1977年 | 14篇 |
1976年 | 15篇 |
1975年 | 10篇 |
1973年 | 11篇 |
1967年 | 10篇 |
排序方式: 共有2960条查询结果,搜索用时 0 毫秒
111.
Maiko Matsushita Yohei Otsuka Naoya Tsutsumida Chiaki Tanaka Akane Uchiumi Koji Ozawa Takuma Suzuki Daiju Ichikawa Hiroyuki Aburatani Shinichiro Okamoto Yutaka Kawakami Yutaka Hattori 《PloS one》2016,11(1)
The homeobox protein, PEPP2 (RHOXF2), has been suggested as a cancer/testis (CT) antigen based on its expression pattern. However, the peptide epitope of PEPP2 that is recognized by cytotoxic T cells (CTLs) is unknown. In this study, we revealed that PEPP2 gene was highly expressed in myeloid leukemia cells and some other hematological malignancies. This gene was also expressed in leukemic stem-like cells. We next identified the first reported epitope peptide (PEPP2271-279). The CTLs induced by PEPP2271-279 recognized PEPP2-positive target cells in an HLA-A*24:02-restricted manner. We also found that a demethylating agent, 5-aza-2’-deoxycytidine, could enhance PEPP2 expression in leukemia cells but not in blood mononuclear cells from healthy donors. The cytotoxic activity of anti-PEPP2 CTL against leukemic cells treated with 5-aza-2’-deoxycytidine was higher than that directed against untreated cells. These results suggest a clinical rationale that combined treatment with this novel antigen-specific immunotherapy together with demethylating agents might be effective in therapy-resistant myeloid leukemia patients. 相似文献
112.
Yasuro Fuse Takahiro Okamoto Kazuhide Hayakawa Hajime Karatani Etsu Yamada 《Limnology》2016,17(3):207-221
Humic substances extracted and purified from bottom sediments of northern Lake Biwa, Japan, in November 2012 and 2013 were characterized using elemental analysis, Fourier-transform infrared spectroscopy, hydrogen-1 nuclear magnetic resonance (1H NMR) analysis, and pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). The infrared (IR) bands in the spectra of humic acids showed the presence of amide linkages and polysaccharides. Results of 1H NMR analysis showed that the humic acids contained approximately twice the number of aliphatic protons as those in the Japanese soil standards used for comparison. Results of the Py-GC/MS analysis, which evaluates pyrolysis temperature dependency of the amount of pyrolysis products, showed that the generation of pyrolysis products in humic acids also differed from that in Japanese soil standards but was similar to that of phytoplankton in Lake Biwa. This analysis method is the first to provide extensive information about the chemical structure of humic substances; conventional Py-GC/MS provides limited information for a single temperature. Data suggest that humic acids in lake sediments are related to chemical characteristics of phytoplankton. Results shed new light on the origins of humic substances in deep-water-lake sediments and provide insights into material recycling in such sediments. 相似文献
113.
Hiroshi Hakoyama Hiroka Fujimori Chiaki Okamoto Sakie Kodama 《Ecological Research》2016,31(2):153-153
Fishery sustainability and the extinction risk of the Japanese eel, Anguilla japonica, are of global concern. The landings of the Japanese eel in Japan comprise a large part of the landings in East Asia. This study provides a compiled dataset of the annual fisheries statistics of the Japanese eel in Japan for stock assessment. The Japanese government has been recording Japanese eel statistics annually since 1984 in five series of annual reports by conducting systematic questionnaire surveys of fisheries managers and associations; however, most of these data are stored in analog format. The key variables in the dataset include the harvest weight of eels, the harvest weight and number of seeds for aquaculture, the number of eels stocked, and the number of management entities engaged in the eel fishery. The levels of spatial aggregation of the variables include the site (river and lake), prefecture, inland and coastal waters, and total in Japan. We also incorporated location data (latitude and longitude) of the site and prefecture into the dataset. Eel harvest includes primarily yellow eels (late juvenile stage) and silver eels (mature stage). Seed harvest in inland waters includes glass eels (intermediate stage between leptocephalus and elver) and elvers (early juvenile stage). Seed harvest from coastal waters comprises glass eels. This dataset provides information to assess long-term trends in the Japanese eel population. 相似文献
114.
Takeuchi Mitsuaki Okamoto Masayuki Watanabe Nobuhide 《International journal of peptide research and therapeutics》2019,25(4):1309-1317
International Journal of Peptide Research and Therapeutics - Very recently, we have reported a new glucagon-like peptide-1 (GLP-1) receptor agonist, SKL-18287, (EC50: 1.2 and 0.13 nM for... 相似文献
115.
Tsutomu Kataoka Manabu Fuchikami Shinji Nojima Nobuyuki Nagashima Motoaki Araki Jun Omura Tatsuhiro Miyagi Yasumasa Okamoto Shigeru Morinobu 《Genes, Brain & Behavior》2019,18(7)
Impaired fear memory extinction (Ext) is one of the hallmark symptoms of post‐traumatic stress disorder (PTSD). However, since the precise mechanism of impaired Ext remains unknown, effective interventions have not yet been established. Recently, hippocampal‐prefrontal brain‐derived neurotrophic factor (BDNF) activity was shown to be crucial for Ext in naïve rats. We therefore examined whether decreased hippocampal‐prefrontal BDNF activity is also involved in the Ext of rats subjected to a single prolonged stress (SPS) as a model of PTSD. BDNF levels were measured by enzyme‐linked immunosorbent assay (ELISA), and phosphorylation of TrkB was measured by immunohistochemistry in the hippocampus and medial prefrontal cortex (mPFC) of SPS rats. We also examined whether BDNF infusion into the ventral mPFC or hippocampus alleviated the impaired Ext of SPS rats in the contextual fear conditioning paradigm. SPS significantly decreased the levels of BDNF in both the hippocampus and mPFC and TrkB phosphorylation in the ventral mPFC. Infusion of BDNF 24 hours after conditioning in the infralimbic cortex (ILC), but not the prelimbic cortex (PLC) nor hippocampus, alleviated the impairment of Ext. Since amelioration of impaired Ext by BDNF infusion did not occur without extinction training, it seems the two interventions must occur consecutively to alleviate impaired Ext. Additionally, BDNF infusion markedly increased TrkB phosphorylation in the ILC of SPS rats. These findings suggest that decreased BDNF signal transduction might be involved in the impaired Ext of SPS rats, and that activation of the BDNF‐TrkB signal might be a novel therapeutic strategy for the impaired Ext by stress. 相似文献
116.
117.
118.
The effect of a serine protease (ASP) secreted from Aeromonas sobria on plasma coagulation was investigated. Proteolytically active ASP promoted human plasma coagulation in a dose-dependent manner. Consistent with the preference for a factor Xa-specific oligo-peptide substrate, ASP produced enzymatic activity from human prothrombin but not from factors IX and X. ASP cleaved prothrombin to produce enzymatically active 37 kDa-fragment displaying the same molecular mass as alpha-thrombin. ASP is the first bacterial serine protease that produces alpha-thrombin, through which ASP may contribute to the induction of thrombotic tendency in disseminated intravascular coagulation complicated with sepsis caused by A. sobria infections. 相似文献
119.
Effects of recombination on hitchhiking diversity in the Brassica self-incompatibility locus complex
In self-incompatibility, a number of S haplotypes are maintained by frequency-dependent selection, which results in trans-specific S haplotypes. The region of several kilobases (approximately 40-60 kb) from SP6 to SP2, including self-incompatibility-related genes and some adjacent genes in Brassica rapa, has high nucleotide diversity due to the hitchhiking effect, and therefore we call this region the "S-locus complex." Recombination in the S-locus complex is considered to be suppressed. We sequenced regions of >50 kb of the S-locus complex of three S haplotypes in B. rapa and found higher nucleotide diversity in intergenic regions than in coding regions. Two highly similar regions of >10 kb were found between BrS-8 and BrS-46. Phylogenetic analysis using trans-specific S haplotypes (called interspecific pairs) of B. rapa and B. oleracea suggested that recombination reduced the nucleotide diversity in these two regions and that the genes not involved in self-incompatibility in the S-locus complex and the kinase domain, but not the S domain, of SRK have also experienced recombination. Recombination may reduce hitchhiking diversity in the S-locus complex, whereas the region from the S domain to SP11 would disfavor recombination. 相似文献
120.
Anandamide (=N-arachidonoylethanolamine) is the first discovered endocannabinoid, and belongs to the class of bioactive, long-chain N-acylethanolamines (NAEs). In animal tissues, anandamide is principally formed together with other NAEs from glycerophospholipid by two successive enzymatic reactions: 1) N-acylation of phosphatidylethanolamine to generate N-acylphosphatidylethanolamine (NAPE) by Ca2+-dependent N-acyltransferase; 2) release of NAE from NAPE by a phosphodiesterase of the phospholipase D type (NAPE-PLD). Although these anandamide-synthesizing enzymes were poorly understood until recently, our cDNA cloning of NAPE-PLD in 2004 enabled molecular-biological approaches to the enzymes. NAPE-PLD is a member of the metallo-beta-lactamase family, which specifically hydrolyzes NAPE among glycerophospholipids, and appears to be constitutively active. Mutagenesis studies suggested that the enzyme functions through a mechanism similar to those of other members of the family. NAPE-PLD is widely expressed in animal tissues, including various regions in rat brain. Its expression level in the brain is very low at birth, and remarkably increases with development. Analysis of NAPE-PLD-deficient mice and other recent studies revealed the presence of NAPE-PLD-independent pathways for the anandamide formation. Furthermore, calcium-independent N-acyltransferase was discovered and characterized. In this article, we will review recent progress in the studies on these enzymes responsible for the biosynthesis of anandamide and other NAEs. 相似文献