全文获取类型
收费全文 | 41814篇 |
免费 | 3329篇 |
国内免费 | 2450篇 |
专业分类
47593篇 |
出版年
2024年 | 60篇 |
2023年 | 484篇 |
2022年 | 1132篇 |
2021年 | 1967篇 |
2020年 | 1225篇 |
2019年 | 1507篇 |
2018年 | 1411篇 |
2017年 | 1084篇 |
2016年 | 1623篇 |
2015年 | 2429篇 |
2014年 | 2851篇 |
2013年 | 3093篇 |
2012年 | 3591篇 |
2011年 | 3401篇 |
2010年 | 1946篇 |
2009年 | 1798篇 |
2008年 | 2092篇 |
2007年 | 1868篇 |
2006年 | 1609篇 |
2005年 | 1428篇 |
2004年 | 1204篇 |
2003年 | 1059篇 |
2002年 | 905篇 |
2001年 | 852篇 |
2000年 | 741篇 |
1999年 | 716篇 |
1998年 | 435篇 |
1997年 | 464篇 |
1996年 | 441篇 |
1995年 | 390篇 |
1994年 | 378篇 |
1993年 | 308篇 |
1992年 | 441篇 |
1991年 | 383篇 |
1990年 | 331篇 |
1989年 | 246篇 |
1988年 | 236篇 |
1987年 | 198篇 |
1986年 | 141篇 |
1985年 | 185篇 |
1984年 | 121篇 |
1983年 | 104篇 |
1982年 | 80篇 |
1981年 | 60篇 |
1980年 | 55篇 |
1979年 | 72篇 |
1978年 | 66篇 |
1977年 | 46篇 |
1976年 | 48篇 |
1973年 | 48篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Huaiyong Luo Manish K. Pandey Aamir W. Khan Jianbin Guo Bei Wu Yan Cai Li Huang Xiaojing Zhou Yuning Chen Weigang Chen Nian Liu Yong Lei Boshou Liao Rajeev K. Varshney Huifang Jiang 《Plant biotechnology journal》2019,17(7):1248-1260
Cultivated peanut (Arachis hypogaea L.) is an important grain legume providing high‐quality cooking oil, rich proteins and other nutrients. Shelling percentage (SP) is the 2nd most important agronomic trait after pod yield and this trait significantly affects the economic value of peanut in the market. Deployment of diagnostic markers through genomics‐assisted breeding (GAB) can accelerate the process of developing improved varieties with enhanced SP. In this context, we deployed the QTL‐seq approach to identify genomic regions and candidate genes controlling SP in a recombinant inbred line population (Yuanza 9102 × Xuzhou 68‐4). Four libraries (two parents and two extreme bulks) were constructed and sequenced, generating 456.89–790.32 million reads and achieving 91.85%–93.18% genome coverage and 14.04–21.37 mean read depth. Comprehensive analysis of two sets of data (Yuanza 9102/two bulks and Xuzhou 68‐4/two bulks) using the QTL‐seq pipeline resulted in discovery of two overlapped genomic regions (2.75 Mb on A09 and 1.1 Mb on B02). Nine candidate genes affected by 10 SNPs with non‐synonymous effects or in UTRs were identified in these regions for SP. Cost‐effective KASP (Kompetitive Allele‐Specific PCR) markers were developed for one SNP from A09 and three SNPs from B02 chromosome. Genotyping of the mapping population with these newly developed KASP markers confirmed the major control and stable expressions of these genomic regions across five environments. The identified candidate genomic regions and genes for SP further provide opportunity for gene cloning and deployment of diagnostic markers in molecular breeding for achieving high SP in improved varieties. 相似文献
993.
Jiao Li Shu‐Hong Li Jun Dong Faisal J. Alibhai Chongyu Zhang Zheng‐Bo Shao Hui‐Fang Song Sheng He Wen‐Juan Yin Jun Wu Richard D. Weisel Shi‐Ming Liu Ren‐Ke Li 《Aging cell》2019,18(6)
Reduced quantity and quality of stem cells in aged individuals hinders cardiac repair and regeneration after injury. We used young bone marrow (BM) stem cell antigen 1 (Sca‐1) cells to reconstitute aged BM and rejuvenate the aged heart, and examined the underlying molecular mechanisms. BM Sca‐1+ or Sca‐1? cells from young (2–3 months) or aged (18–19 months) GFP transgenic mice were transplanted into lethally irradiated aged mice to generate 4 groups of chimeras: young Sca‐1+, young Sca‐1?, old Sca‐1+, and old Sca‐1?. Four months later, expression of rejuvenation‐related genes (Bmi1, Cbx8, PNUTS, Sirt1, Sirt2, Sirt6) and proteins (CDK2, CDK4) was increased along with telomerase activity and telomerase‐related protein (DNA‐PKcs, TRF‐2) expression, whereas expression of senescence‐related genes (p16INK4a, P19ARF, p27Kip1) and proteins (p16INK4a, p27Kip1) was decreased in Sca‐1+ chimeric hearts, especially in the young group. Host cardiac endothelial cells (GFP?CD31+) but not cardiomyocytes were the primary cell type rejuvenated by young Sca‐1+ cells as shown by improved proliferation, migration, and tubular formation abilities. C‐X‐C chemokine CXCL12 was the factor most highly expressed in homed donor BM (GFP+) cells isolated from young Sca‐1+ chimeric hearts. Protein expression of Cxcr4, phospho‐Akt, and phospho‐FoxO3a in endothelial cells derived from the aged chimeric heart was increased, especially in the young Sca‐1+ group. Reconstitution of aged BM with young Sca‐1+ cells resulted in effective homing of functional stem cells in the aged heart. These young, regenerative stem cells promoted aged heart rejuvenation through activation of the Cxcl12/Cxcr4 pathway of cardiac endothelial cells. 相似文献
994.
Man-Hei Cheung Aftab Amin Rentian Wu Yan Qin Lan Zou Zhiling Yu 《Cell cycle (Georgetown, Tex.)》2019,18(5):605-620
Noc3p (Nucleolar Complex-associated protein) is an essential protein in budding yeast DNA replication licensing. Noc3p mediates the loading of Cdc6p and MCM proteins onto replication origins during the M-to-G1 transition by interacting with ORC (Origin Recognition Complex) and MCM (Minichromosome Maintenance) proteins. FAD24 (Factor for Adipocyte Differentiation, clone number 24), the human homolog of Noc3p (hNOC3), was previously reported to play roles in the regulation of DNA replication and proliferation in human cells. However, the role of hNOC3 in replication licensing was unclear. Here we report that hNOC3 physically interacts with multiple human pre-replicative complex (pre-RC) proteins and associates with known replication origins throughout the cell cycle. Moreover, knockdown of hNOC3 in HeLa cells abrogates the chromatin association of other pre-RC proteins including hCDC6 and hMCM, leading to DNA replication defects and eventual apoptosis in an abortive S-phase. In comparison, specific inhibition of the ribosome biogenesis pathway by preventing pre-rRNA synthesis, does not lead to any cell cycle or DNA replication defect or apoptosis in the same timeframe as the hNOC3 knockdown experiments. Our findings strongly suggest that hNOC3 plays an essential role in pre-RC formation and the initiation of DNA replication independent of its potential role in ribosome biogenesis in human cells. 相似文献
995.
Jin‐Zhi Guo Zhen‐Yi Gu Xin‐Xin Zhao Mei‐Yi Wang Xu Yang Yang Yang Wen‐Hao Li Xing‐Long Wu 《Liver Transplantation》2019,9(38)
Flexible Na/K‐ion batteries (NIBs/KIBs) exhibit great potential applications and have drawn much attention due to the continuous development of flexible electronics. However, there are still many huge challenges, mainly the design and construction of flexible electrodes (cathode and anode) with outstanding electrochemical properties. In this work, a unique approach to prepare flexible electrode is proposed by utilizing the commercially available cotton cloth–derived carbon cloth (CC) as a flexible anode and the substrate of a cathode. The binder‐free, self‐supporting, and flexible cathodes (FCC@N/KPB) are prepared by growing Prussian blue microcubes on the flexible CC (FCC). Na/K‐ion full batteries (FCC//FCC@N/KPB) are assembled by using FCC and FCC@N/KPB as anode and cathode, respectively. Electrochemical performance, mechanical flexibility, and practicability of FCC//FCC@N/KPB Na/K‐ion full batteries are evaluated in both coin cells and flexible pouch cells, demonstrating their superior energy‐storage properties (excellent rate performance and cycling stability) and remarkable flexibility (they can work under different bending states). This work provides a new and profound strategy to design flexible electrodes, promoting the development of flexible NIBs/KIBs to be practical and sustainable. 相似文献
996.
Jiang Cui Shanshan Yao Muhammad Ihsan‐Ul‐Haq Junxiong Wu Jang‐Kyo Kim 《Liver Transplantation》2019,9(1)
Carbonaceous materials are widely employed to host Li for stable and safe Li metal batteries while relatively little effort is devoted to tailoring the surface properties of carbon to facilitate uniform Li plating. Herein, the correlation between Li plating behavior and the surface characteristics of electrospun porous carbon nanofibers (PCNFs) is systemically elucidated through experiments and theoretical calculations. It is revealed that the neat carbon surface suffers from severe lattice mismatch with Li metal, hindering uniform Li plating. In contrast, open pores created on the PCNF surface serve as active sites for controlled initial nucleation of Li. The introduction of oxygenated functional groups further facilitates the nucleation of Li on PCNFs through the largely reduced nucleation energy barrier. The Li film uniformly deposited on PCNFs enables efficient use of the whole carbon surface, giving rise to enhanced cyclic stability of the electrode. When used as an anode in lithium–sulfur batteries, the modified electrode delivers an excellent energy density of 385 Wh kg?1 after 100 cycles. The fundamental correlation established in this study is universal to all types of carbonaceous materials and sheds new light on the rational design of high‐performance Li metal anodes by controlling the initial Li nucleation. 相似文献
997.
Yin Hu Wei Chen Tianyu Lei Bin Zhou Yu Jiao Yichao Yan Xinchuan Du Jianwen Huang Chunyang Wu Xuepeng Wang Yang Wang Bo Chen Jun Xu Chao Wang Jie Xiong 《Liver Transplantation》2019,9(7)
Significant progress has achieved for developing lithium–sulfur (Li–S) batteries with high specific capacities and excellent cyclic stability. However, some critical issues emerge when attempts are made to raise the areal sulfur loading and increase the operation current density to meet the standards for various industrial applications. In this work, polyethylenimine‐functionalized carbon dots (PEI‐CDots) are designed and prepared for enhancing performance of the Li–S batteries with high sulfur loadings and operation under high current density situations. Strong chemical binding effects towards polysulfides and fast ion transport property are achieved in the PEI‐CDots‐modified cathodes. At a high current density of 8 mA cm?2, the PEI‐CDots‐modified Li–S battery delivers a reversible areal capacity of 3.3 mAh cm?2 with only 0.07% capacity decay per cycle over 400 cycles at 6.6 mg sulfur loading. Detailed analysis, involving electrochemical impedance spectroscopy, cyclic voltammetry, and density functional theory calculations, is done for the elucidation of the underlying enhancement mechanism by the PEI‐CDots. The strongly localized sulfur species and the promoted Li+ ion conductivity at the cathode–electrolyte interface are revealed to enable high‐performance Li–S batteries with high sulfur loading and large operational current. 相似文献
998.
Yun Lian He Wei Jinshe Wang Chenfang Lei Haichao Li Jinying Li Yongkang Wu Shufeng Wang Hui Zhang Tingfeng Wang Pei Du Jianqiu Guo Weiguo Lu 《Molecular ecology resources》2019,19(6):1637-1646
Soybean cyst nematode (SCN, Heterodera glycines) is a major pest of soybean that is spreading across major soybean production regions worldwide. Increased SCN virulence has recently been observed in both the United States and China. However, no study has reported a genome assembly for H. glycines at the chromosome scale. Herein, the first chromosome‐level reference genome of X12, an unusual SCN race with high infection ability, is presented. Using whole‐genome shotgun (WGS) sequencing, Pacific Biosciences (PacBio) sequencing, Illumina paired‐end sequencing, 10X Genomics linked reads and high‐throughput chromatin conformation capture (Hi‐C) genome scaffolding techniques, a 141.01‐megabase (Mb) assembled genome was obtained with scaffold and contig N50 sizes of 16.27 Mb and 330.54 kilobases (kb), respectively. The assembly showed high integrity and quality, with over 90% of Illumina reads mapped to the genome. The assembly quality was evaluated using Core Eukaryotic Genes Mapping Approach and Benchmarking Universal Single‐Copy Orthologs. A total of 11,882 genes were predicted using de novo, homolog and RNAseq data generated from eggs, second‐stage juveniles (J2), third‐stage juveniles (J3) and fourth‐stage juveniles (J4) of X12, and 79.0% of homologous sequences were annotated in the genome. These high‐quality X12 genome data will provide valuable resources for research in a broad range of areas, including fundamental nematode biology, SCN–plant interactions and co‐evolution, and also contribute to the development of technology for overall SCN management. 相似文献
999.
Ruilin Huang Steve P. McGrath Penny R. Hirsch Ian M. Clark Jonathan Storkey Liyou Wu Jizhong Zhou Yuting Liang 《Microbial biotechnology》2019,12(6):1464-1475
Understanding the changes in plant–microbe interactions is critically important for predicting ecosystem functioning in response to human-induced environmental changes such as nitrogen (N) addition. In this study, the effects of a century-long fertilization treatment (> 150 years) on the networks between plants and soil microbial functional communities, detected by GeoChip, in grassland were determined in the Park Grass Experiment at Rothamsted Research, UK. Our results showed that plants and soil microbes have a consistent response to long-term fertilization—both richness and diversity of plants and soil microbes are significantly decreased, as well as microbial functional genes involved in soil carbon (C), nitrogen (N) and phosphorus (P) cycling. The network-based analyses showed that long-term fertilization decreased the complexity of networks between plant and microbial functional communities in terms of node numbers, connectivity, network density and the clustering coefficient. Similarly, within the soil microbial community, the strength of microbial associations was also weakened in response to long-term fertilization. Mantel path analysis showed that soil C and N contents were the main factors affecting the network between plants and microbes. Our results indicate that century-long fertilization weakens the plant–microbe networks, which is important in improving our understanding of grassland ecosystem functions and stability under long-term agriculture management. 相似文献
1000.
Precipitation and seasonality affect grazing impacts on herbage nutritive values in alpine meadows on the Qinghai-Tibet Plateau 总被引:1,自引:0,他引:1
Aims
Grasslands used for animal husbandry are chosen depending on the nutritive values of dominant herbage species. However, the influence of grazing in combination with precipitation and growing season on the nutritive values of dominant species has not been explicated. 相似文献