全文获取类型
收费全文 | 5875篇 |
免费 | 426篇 |
国内免费 | 5篇 |
出版年
2024年 | 8篇 |
2023年 | 27篇 |
2022年 | 97篇 |
2021年 | 128篇 |
2020年 | 100篇 |
2019年 | 117篇 |
2018年 | 204篇 |
2017年 | 160篇 |
2016年 | 255篇 |
2015年 | 396篇 |
2014年 | 395篇 |
2013年 | 438篇 |
2012年 | 568篇 |
2011年 | 509篇 |
2010年 | 303篇 |
2009年 | 275篇 |
2008年 | 371篇 |
2007年 | 374篇 |
2006年 | 297篇 |
2005年 | 260篇 |
2004年 | 249篇 |
2003年 | 229篇 |
2002年 | 163篇 |
2001年 | 94篇 |
2000年 | 81篇 |
1999年 | 68篇 |
1998年 | 28篇 |
1997年 | 25篇 |
1996年 | 14篇 |
1995年 | 14篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1971年 | 2篇 |
排序方式: 共有6306条查询结果,搜索用时 233 毫秒
151.
Achene morphology of Saussurea species (Asteraceae,Cardueae) in Korea and its systematic implications 下载免费PDF全文
Balkrishna Ghimire Mi Jin Jeong Kyung Mee Lee Kweon Heo Cheul Ho Lee Gang Uk Suh 《Botanical journal of the Linnean Society. Linnean Society of London》2016,181(4):692-710
Achene size and shape, surface sculpturing, and pericarp and testa wall structure of 23 Korean Saussurea spp. were investigated using scanning electron microscopy (SEM) and light microscopy to evaluate the infrageneric relationships and assess their systematic significance. Achene size categories and thickness of the testa epidermis were distinguished using biometric measurements. Four basic types of surface pattern were observed: (1) lineate; (2) striate; (3) reticulate; and (4) colliculate. Saussurea rorinsanensis was found to have some unique achene characteristics, such as a fusiform achene, uniform pappus, presence of epidermal hairs and tangentially elongated, narrow testa epidermal cells. The characteristic achene features for species were found to be achene size and shape, hilum position, surface sculpture, pappus composition, morphology of the pericarp wall and thickness of the testa epidermis. Based on 16 morphological and achene characters, a cladistic analysis resolved three well‐supported clades, with S. eriophylla as the first‐branching taxon. Saussurea pulchella and S. japonica, both belonging to Saussurea subgenus Theodorea, were distant from each other in the 50% majority rule consensus tree and the character distribution cladogram. This cladistic analysis of achene morphology and anatomy should be regarded as giving us a tentative picture of the phylogenetics of Saussurea, and this study may serve as a reference for future hypotheses and studies on the characterization and classification of Saussurea spp. in Korea. 相似文献
152.
Daniel C. Ilut Alexander E. Lipka Namhee Jeong Dong Nyuk Bae Dong Hyun Kim Ji Hong Kim Neelam Redekar Kiwoung Yang Won Park Sung-Taeg Kang Namshin Kim Jung-Kyung Moon M. A. Saghai Maroof Michael A. Gore Soon-Chun Jeong 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2016,129(3):453-468
153.
154.
155.
Role of Arabidopsis AtPI4Kγ3, a type II phosphoinositide 4‐kinase,in abiotic stress responses and floral transition 下载免费PDF全文
Salina Akhter Mohammad N. Uddin In S. Jeong Dae W. Kim Xiao‐Min Liu Jeong D. Bahk 《Plant biotechnology journal》2016,14(1):215-230
Phosphoinositides (PIs) are essential metabolites which are generated by various lipid kinases and rapidly respond to a variety of environmental stimuli in eukaryotes. One of the precursors of important regulatory PIs, phosphatidylinositol (PtdIn) 4‐phosphate, is synthesized by PtdIns 4‐kinases (PI4K). Despite its wide distribution in eukaryotes, its role in plants remains largely unknown. Here, we show that the activity of AtPI4Kγ3 gene, an Arabidopsis (Arabidopsis thaliana) type II PtdIn 4‐kinase, is regulated by DNA demethylation and some abiotic stresses. AtPI4Kγ3 is targeted to the nucleus and selectively bounds to a few PtdIns. It possessed autophosphorylation activity but unexpectedly had no detectable lipid kinase activity. Overexpression of AtPI4Kγ3 revealed enhanced tolerance to high salinity or ABA along with inducible expression of a host of stress‐responsive genes and an optimal accumulation of reactive oxygen species. Furthermore, overexpressed AtPI4Kγ3 augmented the salt tolerance of bzip60 mutants. The ubiquitin‐like domain of AtPI4Kγ3 is demonstrated to be essential for salt stress tolerance. Besides, AtPI4Kγ3‐overexpressed plants showed a late‐flowering phenotype, which was caused by the regulation of some flowering pathway integrators. In all, our results indicate that AtPI4Kγ3 is necessary for reinforcement of plant response to abiotic stresses and delay of the floral transition. 相似文献
156.
Short‐term calorie restriction ameliorates genomewide,age‐related alterations in DNA methylation 下载免费PDF全文
Chul Hong Kim Eun Kyeong Lee Yeon Ja Choi Hye Jin An Hyeong Oh Jeong Daeui Park Byoung Chul Kim Byung Pal Yu Jong Bhak Hae Yung Chung 《Aging cell》2016,15(6):1074-1081
DNA methylation plays major roles in many biological processes, including aging, carcinogenesis, and development. Analyses of DNA methylation using next‐generation sequencing offer a new way to profile and compare methylomes across the genome in the context of aging. We explored genomewide DNA methylation and the effects of short‐term calorie restriction (CR) on the methylome of aged rat kidney. Whole‐genome methylation of kidney in young (6 months old), old (25 months old), and OCR (old with 4‐week, short‐term CR) rats was analyzed by methylated DNA immunoprecipitation and next‐generation sequencing (MeDIP‐Seq). CpG islands and repetitive regions were hypomethylated, but 5′‐UTR, exon, and 3′‐UTR hypermethylated in old and OCR rats. The methylation in the promoter and intron regions was decreased in old rats, but increased in OCR rats. Pathway enrichment analysis showed that the hypermethylated promoters in old rats were associated with degenerative phenotypes such as cancer and diabetes. The hypomethylated promoters in old rats related significantly to the chemokine signaling pathway. However, the pathways significantly enriched in old rats were not observed from the differentially methylated promoters in OCR rats. Thus, these findings suggest that short‐term CR could partially ameliorate age‐related methylation changes in promoters in old rats. From the epigenomic data, we propose that the hypermethylation found in the promoter regions of disease‐related genes during aging may indicate increases in susceptibility to age‐related diseases. Therefore, the CR‐induced epigenetic changes that ameliorate age‐dependent aberrant methylation may be important to CR's health‐ and life‐prolonging effects. 相似文献
157.
Synthesis and Application of C2 and C3 Symmetric (R)‐Phenylglycinol‐Derived Chiral Stationary Phases 下载免费PDF全文
A C3 symmetric (R)‐phenylglycinol N‐1,3,5‐benzenetricarboxylic acid‐derived chiral stationary phase (CSP) and three C2 symmetric (R)‐phenylglycinol CSPs were newly synthesized using o‐, m‐, and p‐phthaloyl dichlorides. © 2016 Wiley Periodicals, Inc. These CSPs were used to compare the resolution of 25 chiral samples using a previously reported 3,5‐dinitrobenzoyl (R)‐phenylglycinol‐derived CSP. Even though all CSPs have the same chiral moiety, the C3 symmetric CSP showed the best resolution. Chirality 28:186–191, 2016.© 2016 Wiley Periodicals, Inc. 相似文献
158.
This study was conducted to identify optimal medium composition for freezing Oryzias dancena embryonic cell lines. Different freezing media consisting of various concentration of dimethyl sulfoxide (DMSO), fetal bovine serum (FBS), and trehalose were prepared and long-term cultured embryonic cell line was frozen in each freezing medium by conventional slow freezing program for 7 days. Through measurement of viability and growth of post-thaw cells frozen in each freezing medium, it was determined that optimal composition of three components was 10 % DMSO, 20 % FBS, and 0.1 M trehalose. The post-thaw cells frozen in optimal freezing medium showed similar morphology and growth rate with non-frozen cells. Next, this condition was applied to two different sets of experiment; (1) freezing of the same cells during expanded period (57 days) and (2) freezing of short-term cultured cells from other batches for 7 days. The viability of post-thaw cells was significantly low and comparable in set 1 and 2, respectively, when compared with the result of long term-cultured cells frozen in optimal freezing medium for 7 days and similar morphology and growth rate with non-frozen counterparts were detected in the post-thaw cells from both sets. In conclusion, this study first reports the optimal medium composition for freezing O. dancena embryonic cells, which can contribute to fish species preservation as well as improvement of cell-based biotechnology by providing stable cell storage. 相似文献
159.
Gudio Veit Radu G. Avramescu Annette N. Chiang Scott A. Houck Zhiwei Cai Kathryn W. Peters Jeong S. Hong Harvey B. Pollard William B. Guggino William E. Balch William R. Skach Garry R. Cutting Raymond A. Frizzell David N. Sheppard Douglas M. Cyr Eric J. Sorscher Jeffrey L. Brodsky Gergely L. Lukacs 《Molecular biology of the cell》2016,27(3):424-433
160.
Won‐Jun Jang Sung Keun Jung Tam Thuy Lu Vo Chul‐Ho Jeong 《Journal of cellular and molecular medicine》2019,23(2):1106-1115
The concept of drug repositioning has recently received considerable attention in the field of oncology. In the present study, we propose that paroxetine can be used as a potent anticancer drug. Paroxetine, one of the selective serotonin reuptake inhibitors (SSRIs), has been widely prescribed for the treatment of depression and anxiety disorders. Recently, SSRIs have been reported to have anticancer activity in various types of cancer cells; however, the underlying mechanisms of their action are not yet known. In this study, we investigated the potential anticancer effect of paroxetine in human colorectal cancer cells, HCT116 and HT‐29. Treatment with paroxetine reduced cell viability, which was associated with marked increase in apoptosis, in both the cell lines. Also, paroxetine effectively inhibited colony formation and 3D spheroid formation. We speculated that the mode of action of paroxetine might be through the inhibition of two major receptor tyrosine kinases – MET and ERBB3 – leading to the suppression of AKT, ERK and p38 activation and induction of JNK and caspase‐3 pathways. Moreover, in vivo experiments revealed that treatment of athymic nude mice bearing HT‐29 cells with paroxetine remarkably suppressed tumour growth. In conclusion, paroxetine is a potential therapeutic option for patients with colorectal cancer. 相似文献