全文获取类型
收费全文 | 3709篇 |
免费 | 197篇 |
国内免费 | 2篇 |
出版年
2022年 | 24篇 |
2021年 | 46篇 |
2020年 | 24篇 |
2019年 | 48篇 |
2018年 | 49篇 |
2017年 | 56篇 |
2016年 | 80篇 |
2015年 | 121篇 |
2014年 | 128篇 |
2013年 | 236篇 |
2012年 | 240篇 |
2011年 | 236篇 |
2010年 | 155篇 |
2009年 | 166篇 |
2008年 | 216篇 |
2007年 | 230篇 |
2006年 | 207篇 |
2005年 | 212篇 |
2004年 | 206篇 |
2003年 | 190篇 |
2002年 | 182篇 |
2001年 | 60篇 |
2000年 | 43篇 |
1999年 | 60篇 |
1998年 | 38篇 |
1997年 | 38篇 |
1996年 | 40篇 |
1995年 | 26篇 |
1994年 | 17篇 |
1993年 | 35篇 |
1992年 | 51篇 |
1991年 | 52篇 |
1990年 | 43篇 |
1989年 | 47篇 |
1988年 | 34篇 |
1987年 | 25篇 |
1986年 | 29篇 |
1985年 | 21篇 |
1984年 | 28篇 |
1983年 | 23篇 |
1982年 | 31篇 |
1981年 | 16篇 |
1980年 | 8篇 |
1979年 | 11篇 |
1978年 | 11篇 |
1976年 | 5篇 |
1975年 | 7篇 |
1974年 | 16篇 |
1973年 | 6篇 |
1972年 | 5篇 |
排序方式: 共有3908条查询结果,搜索用时 15 毫秒
141.
Tomohiro Iguchi Sho Nambara Takaaki Masuda Hisateru Komatsu Masami Ueda Shinya Kidogami Yushi Ogawa Qingjiang Hu Kuniaki Sato Tomoko Saito Hidenari Hirata Shotaro Sakimura Ryutaro Uchi Naoki Hayashi Shuhei Ito Hidetoshi Eguchi Keishi Sugimachi Yoshihiko Maehara Koshi Mimori 《PloS one》2016,11(11)
miR-146a plays important roles in cancer as it directly targets NUMB, an inhibitor of Notch signaling. miR-146a is reportedly regulated by a G>C polymorphism (SNP; rs2910164). This polymorphism affects various cancers, including colorectal cancer (CRC). However, the clinical significance of miR-146a polymorphism in CRC remains unclear. A total of 59 patients with CRC were divided into 2 groups: a CC/CG genotype (n = 32) and a GG genotype (n = 27), based on the miR-146a polymorphism. cDNA microarray analysis was performed using 59 clinical samples. Significantly enriched gene sets in each genotype were extracted using GSEA. We also investigated the association between miR-146a polymorphism and miR-146a, NUMB expression or migratory response in CRC cell lines. The CC/CG genotype was associated with significantly more synchronous liver metastasis (p = 0.007). A heat map of the two genotypes showed that the expression profiles were clearly stratified. GSEA indicated that Notch signaling and JAK/STAT3 signaling were significantly associated with the CC/CG genotype (p = 0.004 and p = 0.023, respectively). CRC cell lines with the pre-miR-146a/C revealed significantly higher miR-146a expression (p = 0.034) and higher NUMB expression and chemotactic activity. In CRC, miR-146a polymorphism is involved in liver metastasis. Identification of this polymorphism could be useful to identify patients with a high risk of liver metastasis in CRC. 相似文献
142.
143.
144.
Yoichiro?OkuboEmail author Osamu?Motohashi Norisuke?Nakayama Ken?Nishimura Rika?Kasajima Yohei?Miyagi Manabu?Shiozawa Emi?Yoshioka Masaki?Suzuki Kota?Washimi Kae?Kawachi Madoka?Nito Yoichi?Kameda Tomoyuki?Yokose 《Diagnostic pathology》2016,11(1):128
Background
As the World Health Organization grading system for gastroenteropancreatic-neuroendocrine tumors (GEP-NETs) may not always correlate with tumor progression, it is imperative that other independent predictors of tumor progression be established. To identify such predictors, we conducted a retrospective histopathological study of hindgut NETs, obtained from endoscopic procedures, and used statistical analyses to evaluate predictive factors.Methods
We first obtained clinicopathological data of cases of hindgut NETs. Tissue sections from tumor samples were prepared and subjected to pathological examination. In particular, we calculated the microvessel density (MVD) and lymphatic microvessel density (LMVD) values, and performed appropriate statistical analyses.Results
A total of 42 cases of hindgut NETs were selected for the study, 41 from the rectum and 1 from the sigmoid colon. Based on the Ki-67 labeling index, 34 cases were classified as NET G1 tumors and 8 as NET G2 tumors. MVD values ranged from 1.4/mm2 to 73.9/mm2 and LMVD values from 0/mm2 to 22.9/mm2. MVD and LMVD were identified as risk factors for venous and lymphatic invasion of hindgut NETs. Moreover, MVD positively correlated with the maximum diameter of the tumor.Conclusions
Tumor progression of NETs may cause angiogenesis and lymphangiogenesis, via an unknown mechanism, as well as lymphovascular invasion. Angiogenesis likely plays an important role in occurrence and progression in the initial phase of hindgut NETs.145.
Reducing Molecular Flexibility by Cyclization for Elucidation of Absolute Configuration by CD Calculations: Daurichromenic Acid
下载免费PDF全文
![点击此处可从《Chirality》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Circular dichroism (CD) calculations of flexible natural products have been difficult because of the large number of low‐energy conformers and ambiguous Boltzmann distributions. In this article, through electronic (ECD) and vibrational (VCD) studies on a natural product, (+)‐daurichromenic acid, we demonstrate that derivatization of a flexible molecule can dramatically reduce its flexibility. This work also shows the usefulness of derivatization for diminishing computational expenses required for optimization and CD calculations, and for increasing the reliability of the assignment of absolute configuration. Chirality 28:453–459, 2016. © 2016 Wiley Periodicals, Inc. 相似文献
146.
Masaki Kikugawa Hiroyasu Tsutsuki Tomoaki Ida Hidemitsu Nakajima Hideshi Ihara 《Bioscience, biotechnology, and biochemistry》2016,80(3):547-553
Ferulic acid (FA) has been reported to exhibit protective effects against amyloid-β (Aβ)-induced neurodegeneration in vitro and in vivo. Recently, we developed two water-soluble FA derivatives: 1-feruloyl glycerol and 1-feruloyl diglycerol. In this study, we examined the neuroprotective effects of these water-soluble FA derivatives on Aβ-induced neurodegeneration both in vitro and in vivo. FA and water-soluble FA derivatives inhibited Aβ aggregation and destabilized pre-aggregated Aβ to a similar extent. Furthermore, water-soluble FA derivatives, as well as FA, inhibited Aβ-induced neuronal cell death in cultured neuronal cells. In in vivo experiments, oral administration of water-soluble FA derivatives to mice improved Aβ-induced dysmnesia assessed by contextual fear conditioning test and protected hippocampal neurons against Aβ-induced neurotoxicity. This study provides useful evidence suggesting that water-soluble FA derivatives are expected to be effective neuroprotective agents. 相似文献
147.
Practical selection methods for rat and mouse round spermatids without DNA staining by flow cytometric cell sorting
下载免费PDF全文
![点击此处可从《Molecular reproduction and development》网站下载免费的PDF全文](/ch/ext_images/free.gif)
148.
149.
Chieko Hosaka Makoto Kunisada Michiyo Koyanagi‐Aoi Taro Masaki Chihiro Takemori Mariko Taniguchi‐Ikeda Takashi Aoi Chikako Nishigori 《Pigment cell & melanoma research》2019,32(5):623-633
Induced pluripotent stem cell (iPSC) technology offers a novel approach for conversion of human primary fibroblasts into melanocytes. During attempts to explore various protocols for differentiation of iPSCs into melanocytes, we found a distinct and self‐renewing cell lineage that could differentiate into melanocytes, named as melanocyte precursor cells (MPCs). The MPCs exhibited a morphology distinctive from that of melanocytes, in lacking either the melanosomal structure or the melanocyte‐specific marker genes MITF, TYR, and SOX10. In addition, gene expression studies in the MPCs showed high‐level expression of WNT5A, ROR2, which are non‐canonical WNT pathway markers, and its related receptor TGFβR2. In contrast, MPC differentiation into melanocytes was achieved by activating the canonical WNT pathway using the GSK3β inhibitor. Our data demonstrated the distinct characteristic of MPCs' ability to differentiate into melanocytes, and the underlying mechanism of interfacing between canonical WNT signaling pathway and non‐canonical WNT signaling pathway. 相似文献
150.
Shinichi Sato Masaki Yoshida Kensuke Hatano Masaki Matsumura Hiroyuki Nakamura 《Bioorganic & medicinal chemistry》2019,27(6):1110-1118
We synthesized novel phenylenediamine derivatives and evaluated them as labeling agents to label proteins in close proximity to a single electron transfer catalyst. We found that N’-acyl-N-methylphenylenediamine labels tyrosine effectively in a model experiment using tris(bipyridine)ruthenium (Ru(bpy)32+) as the single electron transfer catalyst. By changing the substituents on the nitrogen atom of the phenylenediamine derivatives, the electrochemical properties of the labeling agent can be drastically changed. On the other hand, horseradish peroxidase (HRP) also catalyzes the reaction with almost the same oxidation potential as Ru(bpy)32+ (~+1.1?V). HRP proximity labeling is applicable to signal amplification in immunohistochemistry. We evaluated the phenylenediamine derivatives as labeling agents for HRP proximity labeling and signal amplification, and found that N’-acyl-N-methylphenylenediamine is a novel and efficient agent for signal amplification using HRP in immunohistochemistry. 相似文献