全文获取类型
收费全文 | 4435篇 |
免费 | 383篇 |
国内免费 | 284篇 |
出版年
2024年 | 11篇 |
2023年 | 46篇 |
2022年 | 135篇 |
2021年 | 231篇 |
2020年 | 165篇 |
2019年 | 188篇 |
2018年 | 201篇 |
2017年 | 135篇 |
2016年 | 183篇 |
2015年 | 287篇 |
2014年 | 357篇 |
2013年 | 330篇 |
2012年 | 415篇 |
2011年 | 350篇 |
2010年 | 210篇 |
2009年 | 227篇 |
2008年 | 253篇 |
2007年 | 202篇 |
2006年 | 164篇 |
2005年 | 136篇 |
2004年 | 109篇 |
2003年 | 120篇 |
2002年 | 111篇 |
2001年 | 80篇 |
2000年 | 74篇 |
1999年 | 53篇 |
1998年 | 27篇 |
1997年 | 35篇 |
1996年 | 37篇 |
1995年 | 43篇 |
1994年 | 33篇 |
1993年 | 24篇 |
1992年 | 28篇 |
1991年 | 22篇 |
1990年 | 17篇 |
1989年 | 14篇 |
1988年 | 8篇 |
1987年 | 8篇 |
1986年 | 9篇 |
1985年 | 3篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有5102条查询结果,搜索用时 15 毫秒
971.
Five new guaiane sesquiterpenes, 1 – 5 , were isolated from the culture broth of the endophytic fungus Xylaria sp. YM 311647, isolated from Azadirachta indica A. Juss . The structures of these compounds were elucidated on the basis of spectroscopic analyses, and their inhibitory activities against five pathogenic fungi were evaluated. All guaiane sesquiterpenes showed moderate or weak antifungal activities in a broth microdilution assay. 相似文献
972.
Wang Y Chen Y Zhang Y Wu S Ma S Hu S Zhang L Shao C Li M Gao Y 《Biochemical and biophysical research communications》2008,371(3):385-390
Glomerular diseases are leading causes of end-stage renal diseases worldwide. They are considered to be consequences of injury primarily to the three types of glomerular cells. Differential diagnosis typically relies on invasive biopsy findings. We expected that injuries of different glomerular cells would cause different changes in urinary proteome. The goal of this study was to identify differential urinary proteins distinguishing between injuries of different glomerular cells before significant histopathologic changes. Adriamycin nephropathy and Thy1.1 glomerulonephritis were employed as models with different primary impaired cells. ConA-enriched urinary glycoproteome on day3 were profiled by gel-free shotgun tandem mass spectrometry, and compared with self-healthy controls to identify differential urinary proteins for each model. By comparing the changes of the differential proteins between these two models, we identified 39 proteins with different directions of changes, which may potentially be useful in differentiation; and 7 proteins with the same direction of changes, which may be potential indicators of early renal damage. These differential proteins were of several origins: plasma proteins, proteins with urine or kidney specificity, proteins without tissue-specificity (mainly inflammatory mediators) etc. Our results may help better understand the effects of injuries of different glomerular cells at the initial stage, and lead to the discovery of novel early diagnostic markers for human focal segmental glomerulosclerosis (FSGS) and mesangioproliferative glomerulonephritis (MsPGN) which have the same primary impaired cells with adriamycin nephropathy and Thy1.1 glomerulonephritis, respectively. 相似文献
973.
基因瞬时表达是植物中研究目标基因功能的常用手段。在模式植物拟南芥(Arabidopsis thaliana)中, 相比原生质体和农杆菌介导的基因异源表达技术, 利用粒子轰击进行基因瞬时表达一直鲜有报道。其主要原因是拟南芥叶型相对较小、基因枪操作相对烦琐以及基因表达效率差异较大。该研究通过优化双管基因枪系统, 在营养生长旺盛的拟南芥莲座叶中实现GFP和GUS基因高效表达。同时, 通过GUS报告基因明确了坏死诱导因子BAX、Avh238和ATR13/Rpp13激发拟南芥细胞坏死的表型。但在本氏烟(Nicotiana benthamiana)中明显诱导细胞坏死的Avrblb1/RB基因对, 在拟南芥中却丧失了诱导细胞坏死的活性。由于双管基因枪系统每次轰击时设置平行对照, 可有效降低转化实验中的样本变异度, 为拟南芥及其突变体研究中准确评价基因功能和高通量筛选目标基因提供新的技术参考。 相似文献
974.
基因组大小在被子植物物种之间存在着巨大的变异, 但目前对不同生活型被子植物功能性状与基因组大小的关系缺乏统一的认识。本研究基于被子植物245科2,226属11,215个物种的基因组大小数据, 探讨了不同生活型物种种子重量、最大植株高度和叶片氮、磷含量4个功能性状与基因组大小之间的关系。结果表明, 被子植物最大植株高度和种子重量与基因组大小间的关系在草本和木本植物中存在显著差异。草本植物最大植株高度与基因组大小的关系不显著, 但种子重量与其呈极显著的正相关关系。木本植物最大植株高度与基因组大小显著负相关, 但种子重量与其关系不显著。木本植物叶片氮含量与基因组大小呈显著正相关, 但其他生活型植物的叶片氮、磷含量与基因组大小均无显著相关性。本研究表明被子植物功能性状与基因组大小的相关性在不同生活型间存在差异, 这为深入研究植物多种功能性状和植物生活型与基因组大小的权衡关系在植物演化和生态适应中的作用提供了重要依据。 相似文献
975.
Han Qian Jiazhuang Tian Xiaozhou Jiang Bangcui Zhang Xueliang Li Yanhua Yang Shulin Gao Lin Shao Fumin Li 《Luminescence》2024,39(4):e4729
To further explore the relationship between aryl substituents and mechanofluorochromic (MFC) behaviors, four salicylaldimine-based difluoroboron complexes (ts-Ph BF2, ts-Ph-NA BF2, ts-2NA BF2, and ts-triphenylamine [TPA] BF2), including aromatic substituents with different steric hindrance effects, were designed and successfully synthesized. Four complexes with twisted molecular conformation displayed intramolecular charge transfer and aggregation-induced emission properties. Under external mechanical stimuli, the as-synthesized powders of ts-Ph BF2, ts-Ph-NA BF2, and ts-TPA BF2 exhibited redshift fluorescence emission behaviors, and ts-Ph BF2 and ts-TPA BF2 could be recovered to original shifts by fuming, but ts-Ph-NA BF2 displayed irreversible switching. ts-2NA BF2 had no change during the grinding and fuming processes. The results indicated that the MFC behaviors could be attributed to the phase transformation between the well-defined crystalline and disordered amorphous states by X-ray diffraction measurement. Further research illustrated that ts-TPA BF2 with the most significant MFC phenomenon could be applied in data security protection in ink-free rewritable paper. 相似文献
976.
Renying Wang Peijing Zhang Jingjing Wang Lifeng Ma Weigao E Shengbao Suo Mengmeng Jiang Jiaqi Li Haide Chen Huiyu Sun Lijiang Fei Ziming Zhou Yincong Zhou Yao Chen Weiqi Zhang Xinru Wang Yuqing Mei Zhongyi Sun Chengxuan Yu Jikai Shao Yuting Fu Yanyu Xiao Fang Ye Xing Fang Hanyu Wu Qile Guo Xiunan Fang Xia Li Xianzhi Gao Dan Wang Peng-Fei Xu Rui Zeng Gang Xu Lijun Zhu Lie Wang Jing Qu Dan Zhang Hongwei Ouyang He Huang Ming Chen Shyh-Chang NG Guang-Hui Liu Guo-Cheng Yuan Guoji Guo Xiaoping Han 《Nucleic acids research》2023,51(2):501
Individual cells are basic units of life. Despite extensive efforts to characterize the cellular heterogeneity of different organisms, cross-species comparisons of landscape dynamics have not been achieved. Here, we applied single-cell RNA sequencing (scRNA-seq) to map organism-level cell landscapes at multiple life stages for mice, zebrafish and Drosophila. By integrating the comprehensive dataset of > 2.6 million single cells, we constructed a cross-species cell landscape and identified signatures and common pathways that changed throughout the life span. We identified structural inflammation and mitochondrial dysfunction as the most common hallmarks of organism aging, and found that pharmacological activation of mitochondrial metabolism alleviated aging phenotypes in mice. The cross-species cell landscape with other published datasets were stored in an integrated online portal—Cell Landscape. Our work provides a valuable resource for studying lineage development, maturation and aging. 相似文献
977.
Jocelyn Chan Joyce Chan Lily Shao Scott S. Stawicki Victoria C. Pham Rob W. Akita Marc Hafner Lisa Crocker Kebing Yu James T. Koerber Gabriele Schaefer Laetitia Comps-Agrar 《The Journal of biological chemistry》2023,299(1)
Fibroblast growth factor receptor 1 (FGFR1) is a receptor tyrosine kinase that plays a major role in developmental processes and metabolism. The dysregulation of FGFR1 through genetic aberrations leads to skeletal and metabolic diseases as well as cancer. For this reason, FGFR1 is a promising therapeutic target, yet a very challenging one due to potential on-target toxicity. More puzzling is that both agonistic and antagonistic FGFR1 antibodies are reported to exhibit similar toxicity profiles in vivo, namely weight loss. In this study, we aimed to assess and compare the mechanism of action of these molecules to better understand this apparent contradiction. By systematically comparing the binding of these antibodies and the activation or the inhibition of the major FGFR1 signaling events, we demonstrated that the molecules displayed similar properties and can behave either as an agonist or antagonist depending on the presence or the absence of the endogenous ligand. We further demonstrated that these findings translated in xenografts mice models. In addition, using time-resolved FRET and mass spectrometry analysis, we showed a functionally distinct FGFR1 active conformation in the presence of an antibody that preferentially activates the FGFR substrate 2 (FRS2)-dependent signaling pathway, demonstrating that modulating the geometry of a FGFR1 dimer can effectively change the signaling outputs and ultimately the activity of the molecule in preclinical studies. Altogether, our results highlighted how bivalent antibodies can exhibit both agonistic and antagonistic activities and have implications for targeting other receptor tyrosine kinases with antibodies. 相似文献
978.
979.
Qun-qi Hu Xiao-fen He Yi-qi Ma Li-qian Ma Si-ying Qu Han-zhi Wang Yu-rong Kang Lu-hang Chen Xiang Li Bo-yu Liu Xiao-mei Shao Jun-fan Fang Yi Liang Jian-qiao Fang Yong-liang Jiang 《Purinergic signalling》2023,19(1):29
Diabetic neuropathic pain (DNP) is highly common in diabetes patients. P2X receptors play critical roles in pain sensitization. We previously showed that elevated P2X3 expression in dorsal root ganglion (DRG) contributes to DNP. However, the role of other P2X receptors in DNP is unclear. Here, we established the DNP model using a single high-dose streptozotocin (STZ) injection and investigated the expression of P2X genes in the DRG. Our data revealed elevated P2X2, P2X4, and P2X7 mRNA levels in DRG of DNP rats. The protein levels of P2X4 and P2X7 in DNP rats increased, but the P2X2 did not change significantly. To study the role of P2X4 and P2X7 in diabetes-induced hyperalgesia, we treated the DNP rats with TNP-ATP (2’,3’-O-(2,4,6-trinitrophenyl)-adenosine 5’-triphosphate), a nonspecific P2X1–7 antagonist, and found that TNP-ATP alleviated thermal hyperalgesia in DNP rats. 2 Hz electroacupuncture is analgesic against DNP and could downregulate P2X4 and P2X7 expression in DRG. Our findings indicate that P2X4 and P2X7 in L4–L6 DRGs contribute to diabetes-induced hyperalgesia, and that EA reduces thermal hyperalgesia and the expression of P2X4 and P2X7. 相似文献
980.