全文获取类型
收费全文 | 12705篇 |
免费 | 990篇 |
国内免费 | 4篇 |
专业分类
13699篇 |
出版年
2024年 | 12篇 |
2023年 | 55篇 |
2022年 | 176篇 |
2021年 | 314篇 |
2020年 | 165篇 |
2019年 | 211篇 |
2018年 | 273篇 |
2017年 | 272篇 |
2016年 | 385篇 |
2015年 | 713篇 |
2014年 | 762篇 |
2013年 | 832篇 |
2012年 | 1145篇 |
2011年 | 1017篇 |
2010年 | 644篇 |
2009年 | 572篇 |
2008年 | 796篇 |
2007年 | 768篇 |
2006年 | 721篇 |
2005年 | 634篇 |
2004年 | 619篇 |
2003年 | 506篇 |
2002年 | 490篇 |
2001年 | 292篇 |
2000年 | 248篇 |
1999年 | 193篇 |
1998年 | 87篇 |
1997年 | 77篇 |
1996年 | 60篇 |
1995年 | 48篇 |
1994年 | 36篇 |
1993年 | 40篇 |
1992年 | 47篇 |
1991年 | 60篇 |
1990年 | 48篇 |
1989年 | 52篇 |
1988年 | 38篇 |
1987年 | 29篇 |
1986年 | 28篇 |
1985年 | 37篇 |
1984年 | 21篇 |
1983年 | 20篇 |
1982年 | 9篇 |
1981年 | 12篇 |
1979年 | 13篇 |
1978年 | 13篇 |
1977年 | 11篇 |
1974年 | 12篇 |
1973年 | 14篇 |
1972年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
92.
93.
Drought stress has detrimental effects on plants. Although the abscisic acid (ABA)‐mediated drought response is well established, defensive mechanisms to cope with dehydration‐induced proteotoxicity have been rarely studied. DRR1 was identified as an Arabidopsis drought‐induced gene encoding an ER‐localized RING‐type E3 Ub ligase. Suppression of DRR1 markedly reduced tolerance to drought and proteotoxic stress without altering ABA‐mediated germination and stomatal movement. Proteotoxicity‐ and dehydration‐induced insoluble ubiquitinated protein accumulation was more obvious in DRR1 loss‐of‐function plants than in wild‐type plants. These results suggest that DRR1 is involved in an ABA‐independent drought stress response possibly through the mitigation of dehydration‐induced proteotoxic stress. 相似文献
94.
Jang Hye Jin Choi Ji Yeon Kim Kangjoon Yong Seung Hyun Kim Yeon Wook Kim Song Yee Kim Eun Young Jung Ji Ye Kang Young Ae Park Moo Suk Kim Young Sam Cho Young-Jae Lee Sang Hoon 《Respiratory research》2021,22(1):1-9
IL-35 subunit EBI3 is up-regulated in pulmonary fibrosis tissues. In this study, we investigated the pathological role of EBI3 in pulmonary fibrosis and dissected the underlying molecular mechanism. Bleomycin-induced pulmonary fibrosis mouse model was established, and samples were performed gene expression analyses through RNAseq, qRT-PCR and Western blot. Wild type and EBI3 knockout mice were exposed to bleomycin to investigate the pathological role of IL-35, via lung function and gene expression analyses. Primary lung epithelial cells were used to dissect the regulatory mechanism of EBI3 on STAT1/STAT4 and STAT3. IL-35 was elevated in both human and mouse with pulmonary fibrosis. EBI3 knockdown aggravated the symptoms of pulmonary fibrosis in mice. EBI3 deficiency enhanced the expressions of fibrotic and extracellular matrix-associated genes. Mechanistically, IL-35 activated STAT1 and STAT4, which in turn suppressed DNA enrichment of STAT3 and inhibited the fibrosis process. IL-35 might be one of the potential therapeutic targets for bleomycin-induced pulmonary fibrosis. 相似文献
95.
Miroslava Katsur Zhenhe He Vladimir Vinokur Randolph Corteling Derek M Yellon Sean M Davidson 《Journal of cellular and molecular medicine》2021,25(9):4455-4465
Myocardial infarction requires urgent reperfusion to salvage viable heart tissue. However, reperfusion increases infarct size further by promoting mitochondrial damage in cardiomyocytes. Exosomes from a wide range of different cell sources have been shown to activate cardioprotective pathways in cardiomyocytes, thereby reducing infarct size. Yet, it is currently challenging to obtain highly pure exosomes in quantities enough for clinical studies. To overcome this problem, we used exosomes isolated from CTX0E03 neuronal stem cells, which are genetically stable, conditionally inducible and can be produced on an industrial scale. However, it is unknown whether exosomes from neuronal stem cells may reduce cardiac ischaemia/reperfusion injury. In this study, we demonstrate that exosomes from differentiating CTX0E03 cells can reduce infarct size in mice. In an in vitro assay, these exosomes delayed cardiomyocyte mitochondrial permeability transition pore opening, which is responsible for cardiomyocyte death after reperfusion. The mechanism of MPTP inhibition was via gp130 signalling and the downstream JAK/STAT pathway. Our results support previous findings that exosomes from non-cardiomyocyte-related cells produce exosomes capable of protecting cardiomyocytes from myocardial infarction. We anticipate our findings may encourage scientists to use exosomes obtained from reproducible clinical-grade stocks of cells for their ischaemia/reperfusion studies. 相似文献
96.
97.
The purpose of this article is to describe and analyze the edTPA, a performance assessment created by the Stanford Center for Assessment, Learning, and Equity (SCALE) and administered by Pearson, Inc., to assess the professional readiness of student teachers. We challenge claims made in support of using this assessment, specifically within the context of arts teacher preparation programs, and we address areas of immediate critical concern to make alternative recommendations. 相似文献
98.
Joo-Hyun Kim Eun-Hyang Lee Hye-jeong Park Eui-Kyun Park Tae-Geon Kwon Hong-In Shin Je-Yoel Cho 《Molecules and cells》2013,35(6):543-549
Adult human dental pulp stem cells (hDPSCs) are a unique population of precursor cells those are isolated from postnatal dental pulp and have the ability to differentiate into a variety of cell types utilized for the formation of a reparative dentin-like complex. Using LC-MS/MS proteomics approaches, we identified the proteins secreted from the differentiating hDPSCs in mineralization media. Lysyl oxidase-like 2 (LOXL2) was identified as a protein that was down-regulated in the hDPSCs that differentiate into odontoblast-like cells. The role of LOXL2 has not been studied in dental pulp stem cells. LOXL2 mRNA levels were reduced in differentiating hDPSCs, whereas the levels of other LOX family members including LOX, LOXL1, LOXL3, and LOXL4, are increased. The protein expression and secretion levels of LOXL2 were also decreased during odontogenic differentiation. Recombinant LOXL2 protein treatment to hDPSCs resulted in a dose-dependent decrease in the early differentiation and the mineralization accompanying with the lower levels of odontogenic markers such as DSPP, DMP-1 and ALP. These results suggest that LOXL2 has a negative effect on the differentiation of hDPSCs and blocking LOXL2 can promote the hDPSC differentiation to odontoblasts. 相似文献
99.
Seung Hyeok Seok Jong-Ik Heo Ji-Hye Hwang Yi-Rang Na Jang-Hyuk Yun Eun Hui Lee Jong-Wan Park Chung-Hyun Cho 《Molecules and cells》2013,35(6):550-556
The angiopoietin/Tie2 system is an important regulator of angiogenesis and inflammation. In addition to its functions in endothelial cells, Tie2 expression on non-endothelial cells allows for angiopoietin ligands to stimulate the cells. Although Ang1 is a strong Tie2 receptor agonist, little is known regarding the effect of Ang1 on non-endothelial cells, such as monocytes and macrophages. In this study, we found that Ang1 functionally binds to and stimulates monocytes via p38 and Erk1/2 phosphorylation. Ang1-mediated monocyte stimulation is associated with proinflammatory cytokine TNF-α expression. We also determined that Ang1 switched macrophage differentiation toward a pro-inflammatory phenotype, even in the presence of an anti-inflammatory mediator. These findings suggest that Ang1 plays a role in stimulating pro-inflammatory responses and could provide a new strategy by which to manage inflammatory responses. 相似文献
100.
Kristyn Echterling-Savage Florence D. DiGennaro Reed L. Keith Miller Sean Savage 《Journal of applied animal welfare science : JAAWS》2013,16(2):181-197
Problem behavior of companion animals poses a threat to caregivers, other targets of problem behavior (e.g., strangers, other nonhuman animals), and those animals engaging in problem behavior. This study examined the effects of an aggression reduction procedure (ARP) on dog problem behavior. After a baseline condition showing caregivers were unsuccessful in reducing dog aggression and the behaviors preceding aggression, caregivers were trained to implement a procedure to address dog problem behavior in relatively simple contexts. Generalization programming then was used to target caregiver plan implementation and dog problem behavior in more complex contexts. The ARP effectively reduced dog aggression for all dogs. A slight reduction and increased variability in dog precursor behavior was observed when the ARP was implemented. In addition, caregivers and experts rated the goals, procedures, and effects as acceptable. Implications of these findings are discussed. 相似文献