全文获取类型
收费全文 | 76949篇 |
免费 | 5586篇 |
国内免费 | 5118篇 |
专业分类
87653篇 |
出版年
2024年 | 157篇 |
2023年 | 1063篇 |
2022年 | 2418篇 |
2021年 | 4115篇 |
2020年 | 2636篇 |
2019年 | 3257篇 |
2018年 | 3192篇 |
2017年 | 2320篇 |
2016年 | 3303篇 |
2015年 | 4856篇 |
2014年 | 5601篇 |
2013年 | 6051篇 |
2012年 | 7096篇 |
2011年 | 6221篇 |
2010年 | 3763篇 |
2009年 | 3367篇 |
2008年 | 3782篇 |
2007年 | 3395篇 |
2006年 | 2969篇 |
2005年 | 2416篇 |
2004年 | 2013篇 |
2003年 | 1676篇 |
2002年 | 1448篇 |
2001年 | 1241篇 |
2000年 | 1226篇 |
1999年 | 1136篇 |
1998年 | 679篇 |
1997年 | 669篇 |
1996年 | 679篇 |
1995年 | 625篇 |
1994年 | 550篇 |
1993年 | 382篇 |
1992年 | 575篇 |
1991年 | 441篇 |
1990年 | 411篇 |
1989年 | 285篇 |
1988年 | 247篇 |
1987年 | 234篇 |
1986年 | 166篇 |
1985年 | 194篇 |
1984年 | 110篇 |
1983年 | 117篇 |
1982年 | 71篇 |
1981年 | 58篇 |
1980年 | 37篇 |
1979年 | 61篇 |
1977年 | 30篇 |
1974年 | 38篇 |
1973年 | 34篇 |
1972年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Hui Liu Xiang Li Matthew D. Dun Sam Faulkner Chen Chen Jiang Hubert Hondermarck 《Proteomics》2020,20(10)
Pancreatic cancer has a dismal prognosis and to date there are no targeted therapies for this malignancy. Using shotgun proteomics, the mRNA binding protein cold shock domain containing E1 (CSDE1), also called upstream‐of‐N‐Ras, is detected in pancreatic cancer cell lines but not in normal pancreatic epithelial cells. The expression of CSDE1 in pancreatic cancer cells is confirmed by Western blotting and immunohistochemistry of human pancreatic tumors. In vitro functional assays show that siRNA downregulation of CSDE1 or gene knockout using CRISPR‐Cas9 significantly reduce the invasiveness of pancreatic cancer cells. Together, this study reveals that CSDE1 is overexpressed in pancreatic cancer and is a potential therapeutic target to inhibit pancreatic cancer cell invasion. 相似文献
992.
Fang Liu Kratika Singhal Rowan Matney Swati Acharya Cezmi A. Akdis Kari C. Nadeau Allis S. Chien Ryan D. Leib 《Proteomics》2020,20(11)
The analytical scale of most mass‐spectrometry‐based targeted proteomics assays is usually limited by assay performance and instrument utilization. A recently introduced method, called triggered by offset, multiplexed, accurate mass, high resolution, and absolute quantitation (TOMAHAQ), combines both peptide and sample multiplexing to simultaneously improve analytical scale and quantitative performance. In the present work, critical technical requirements and data analysis considerations for successful implementation of the TOMAHAQ technique based on the study of a total of 185 target peptides across over 200 clinical plasma samples are discussed. Importantly, it is observed that significant interference originate from the TMTzero reporter ion used for the synthetic trigger peptides. This interference is not expected because only TMT10plex reporter ions from the target peptides should be observed under typical TOMAHAQ conditions. In order to unlock the great promise of the technique for high throughput quantification, here a post‐acquisition data correction strategy to deconvolute the reporter ion superposition and recover reliable data is proposed. 相似文献
993.
994.
995.
Junhui Zhou Dongdong Li Guoming Wang Fuxi Wang Merixia Kunjal Dirk Joldersma Zhongchi Liu 《植物学报(英文版)》2020,62(3):269-286
Fruit crops, including apple, orange, grape,banana, strawberry, watermelon, kiwifruit and tomato, not only provide essential nutrients for human life but also contribute to the major agricultural output and economic growth of many countries and regions in the world. Recent advancements in genome editing provides an unprecedented opportunity for the genetic improvement of these agronomically important fruit crops. Here, we summarize recent reports of applying CRISPR/Cas9 to fruit crops,including efforts to reduce disease susceptibility, change plant architecture or flower morphology, improve fruit quality traits, and increase fruit yield. We discuss challenges facing fruit crops as well as new improvements and platforms that could be used to facilitate genome editing in fruit crops, including d Cas9-base-editing to introduce desirable alleles and heat treatment to increase editing efficiency. In addition, we highlight what we see as potentially revolutionary development ranging from transgene-free genome editing to de novo domestication of wild relatives. Without doubt, we now see only the beginning of what will eventually be possible with the use of the CRISPR/Cas9 toolkit. Efforts to communicate with the public and an emphasis on the manipulation of consumerfriendly traits will be critical to facilitate public acceptance of genetically engineered fruits with this new technology. 相似文献
996.
Zipeng Yu Yang Xu Lifei Zhu Lei Zhang Lin Liu Di Zhang Dandan Li Changai Wu Jinguang Huang Guodong Yang Kang Yan Shizhong Zhang Chengchao Zheng 《植物学报(英文版)》2020,62(4):403-420
Low molecular weight secreted peptides have recently been shown to affect multiple aspects of plant growth, development, and defense responses.Here, we performed stepwise BLAST filtering to identify unannotated peptides from the Arabidopsis thaliana protein database and uncovered a novel secreted peptide family, secreted transmembrane peptides(STMPs). These low molecular weight peptides, which consist of an N-terminal signal peptide and a transmembrane domain, were primarily localized to extracellular compartments but were also detected in the endomembrane system of the secretory pathway, including the endoplasmic reticulum and Golgi. Comprehensive bioinformatics analysis identified 10 STMP family members that are specific to the Brassicaceae family. Brassicaceae plants showed dramatically inhibited root growth uponexposure to chemically synthesized STMP1 and STMP2.Arabidopsis overexpressing STMP1, 2, 4, 6, or 10 exhibited severely arrested growth, suggesting that STMPs are involved in regulating plant growth and development. In addition, in vitro bioassays demonstrated that STMP1,STMP2, and STMP10 have antibacterial effects against Pseudomonas syringae pv. tomato DC3000, Ralstonia solanacearum, Bacillus subtilis, and Agrobacterium tumefaciens, demonstrating that STMPs are antimicrobial peptides. These findings suggest that STMP family members play important roles in various developmental events and pathogen defense responses in Brassicaceae plants. 相似文献
997.
The mechanism and function of active DNA demethylation in plants 总被引:1,自引:0,他引:1
DNA methylation is a conserved and important epigenetic mark in both mammals and plants.DNA methylation can be dynamically established,maintained,and removed through different pathways.In plants,active DNA demethylation is initiated by the RELEASE OF SILENCING 1(ROS1)family of bifunctional DNA glycosylases/lyases.Accumulating evidence suggests that DNA demethylation is important in many processes in plants.In this review,we summarize recent studies on the enzymes and regulatory factors that have been identified in the DNA demethylation pathway.We also review the functions of active DNA demethylation in plant development as well as biotic and abiotic stress responses.Finally,we highlight those aspects of DNA demethylation that require additional research. 相似文献
998.
Opoku Yeboah Kwaku Liu Zhihang Afrifa Justice Khoso Mir Hassan Ren Guiping Li Deshan 《International journal of peptide research and therapeutics》2020,26(1):107-119
International Journal of Peptide Research and Therapeutics - Fibroblast growth factor-21 (FGF21) is a member of the family of fibroblast growth factors (FGFs). FGF21 (synthesized by many organs)... 相似文献
999.
Rong‐rong Zhu Qian Chen Zhi‐bo Liu Han‐guang Ruan Qi‐cai Wu Xue‐liang Zhou 《Journal of cellular and molecular medicine》2020,24(14):7907-7914
Increased expression and activity of cardiac and circulating cathepsin D and soluble fms‐like tyrosine kinase‐1 (sFlt‐1) have been demonstrated to induce and promote peripartum cardiomyopathy (PPCM) via promoting cleavage of 23‐kD prolactin (PRL) to 16‐kD PRL and neutralizing vascular endothelial growth factor (VEGF), respectively. We hypothesized that activation of Hes1 is proposed to suppress cathepsin D via activating Stat3, leading to alleviated development of PPCM. In the present study, we aimed to investigate the role of Notch1/Hes1 pathway in PPCM. Pregnant mice between prenatal 3 days and postpartum 3 weeks were fed with LY‐411575 (a notch inhibitor, 10 mg/kg/d). Ventricular function and pathology were evaluated by echocardiography and histological analysis. Western blotting analysis was used to examine the expression at the protein level. The results found that inhibition of Notch1 significantly promoted postpartum ventricular dilatation, myocardial hypertrophy and myocardial interstitial fibrosis and suppressed myocardial angiogenesis. Western blotting analysis showed that inhibition of Notch1 markedly increased cathepsin D and sFlt‐1, reduced Hes1, phosphorylated Stat3 (p‐Stat3), VEGFA and PDGFB, and promoted cleavage of 23k‐D PRL to 16‐kD PRL. Collectively, inhibition of Notch1/Hes1 pathway induced and promoted PPCM via increasing the expressions of cathepsin D and sFlt‐1. Notch1/Hes1 was a promising target for prevention and therapeutic regimen of PPCM. 相似文献
1000.
Xiao Yu Wei Lu Chan Way Ng Shuoyu Xu Yao Wu Shili Chen Yuren Gao Yijian Zhang Qingqing Zhang Yuzhen Xu Yingbin Liu Sheng Li 《Journal of cellular and molecular medicine》2020,24(13):7670-7674
Gallbladder carcinoma (GBC) is a vicious and invasive disease. The major challenge in the clinical treatment of GBC is the lack of a suitable prognosis method. Chemokine receptors such as CXCR3, CXCR4 and CXCR7 play vital roles in the process of tumour progression and metastasis. Their expression levels and distribution are proven to be indicative of the progression of GBC, but are hard to be decoded by conventional pathological methods, and therefore, not commonly used in the prognosis of GBC. In this study, we developed a computer‐aided image analysis method, which we used to quantitatively measure the expression levels of CXCR3, CXCR4 and CXCR7 in the nuclei and cytoplasm of glandular and interstitial cells from a cohort of 55 GBC patients. We found that CXCR3, CXCR4 and CXCR7 expressions are associated with the clinicopathological variables of GBC. Cytoplasmic CXCR3, nuclear CXCR7 and cytoplasmic CXCR7 were significant predictive factors of histology invasion, whereas cytoplasmic CXCR4 and nuclear CXCR4 were significantly correlated with T and N stage and were associated with the overall survival and disease‐free survival. These results suggest that the quantification and localisation of CXCR3, CXCR4 and CXCR7 expressions in different cell types should be considered using computer‐aided assessment to improve the accuracy of prognosis in GBC. 相似文献