全文获取类型
收费全文 | 113769篇 |
免费 | 1807篇 |
国内免费 | 1797篇 |
出版年
2024年 | 36篇 |
2023年 | 268篇 |
2022年 | 389篇 |
2021年 | 1032篇 |
2020年 | 691篇 |
2019年 | 925篇 |
2018年 | 12501篇 |
2017年 | 11142篇 |
2016年 | 8259篇 |
2015年 | 1912篇 |
2014年 | 1799篇 |
2013年 | 2051篇 |
2012年 | 6094篇 |
2011年 | 14436篇 |
2010年 | 12868篇 |
2009年 | 9031篇 |
2008年 | 10691篇 |
2007年 | 12187篇 |
2006年 | 1092篇 |
2005年 | 1222篇 |
2004年 | 1581篇 |
2003年 | 1535篇 |
2002年 | 1244篇 |
2001年 | 562篇 |
2000年 | 478篇 |
1999年 | 306篇 |
1998年 | 181篇 |
1997年 | 182篇 |
1996年 | 192篇 |
1995年 | 162篇 |
1994年 | 142篇 |
1993年 | 131篇 |
1992年 | 171篇 |
1991年 | 187篇 |
1990年 | 132篇 |
1989年 | 104篇 |
1988年 | 115篇 |
1987年 | 110篇 |
1986年 | 71篇 |
1985年 | 89篇 |
1984年 | 57篇 |
1983年 | 70篇 |
1982年 | 29篇 |
1981年 | 26篇 |
1979年 | 35篇 |
1978年 | 28篇 |
1975年 | 34篇 |
1972年 | 258篇 |
1971年 | 292篇 |
1962年 | 25篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Rui Li Liu Wang Yujing Li Ruirui Zhao Yuelin Zhang Jiping Sheng Peihua Ma Lin Shen 《Physiologia plantarum》2020,170(4):569-579
Tomato is one of the most popular horticultural crops, and many commercial tomato cultivars are particularly susceptible to Botrytis cinerea. Non-expressor of pathogenesis-related gene 1 (NPR1) is a critical component of the plant defense mechanisms. However, our understanding of how SlNPR1 influences disease resistance in tomato is still limited. In this study, two independent slnpr1 mutants were used to study the role of SlNPR1 in tomato resistance against B. cinerea. Compared to (WT), slnpr1 leaves exhibited enhanced resistance against B. cinerea with smaller lesion sizes, higher activities of chitinase (CHI), β-1, 3-glucanases (GLU) and phenylalanine ammonia-lyase (PAL), and significantly increased expressions of pathogenesis-related genes (PRs). The increased activities of peroxidase (POD), ascorbate peroxidase (APX) and decreased catalase (CAT) activities collectively regulated reactive oxygen species (ROS) homeostasis in slnpr1 mutants. The integrity of the cell wall in slnpr1 mutants was maintained. Moreover, the enhanced resistance was further reflected by induction of defense genes involved in jasmonic acid (JA) and ethylene (ET) signaling pathways. Taken together, these findings revealed that knocking out SlNPR1 resulted in increased activities of defense enzymes, changes in ROS homeostasis and integrity of cell walls, and activation of JA and ET pathways, which confers resistance against B. cinerea in tomato plants. 相似文献
992.
Li Zengqiang Ma Lei Zhang Yong Zhao Wenhui Zhao Bingzi Zhang Jiabao 《Plant and Soil》2020,448(1-2):383-397
Plant and Soil - Wheat (Triticum aestivum L.) cultivars vary in their resistance to Fusarium head blight (FHB), while it is poorly understood how different cultivars influence FHB-causing Fusarium... 相似文献
993.
Wang Pei Wang Chun-Mei Gao Li Cui Yan-Nong Yang Hai-Li de Silva Nayana D. G. Ma Qing Bao Ai-Ke Flowers Timothy J. Rowland Owen Wang Suo-Min 《Plant and Soil》2020,448(1-2):603-620
Plant and Soil - Uncontrolled uptake of Na+ is the reason that many species are sensitive to salinity. Suberin is a protective barrier found in the walls of root endodermal cells that appears to be... 相似文献
994.
Plant and Soil - Although the linkages between aboveground photosynthates production and belowground respiration processes have been well studied, doubts remain as to the extent that photosynthate... 相似文献
995.
Mucha Joanna Zadworny Marcin Helmisaari Heljä-Sisko Nihlgård Bengt Repo Tapani Żytkowiak Maciej Małek Stanisław Reich Peter B. Oleksyn Jacek 《Plant and Soil》2020,455(1-2):507-518
Plant and Soil - Any grouping of tree species concerned with SOC sequestration should include trees that are as homogeneous as possible in their carbon sequestration. We propose a classification of... 相似文献
996.
Jia Chunhua Yu Xiaojing Zhang Min Liu Zhiguang Zou Peng Ma Jun Xu Yachun 《Journal of Plant Growth Regulation》2020,39(2):631-640
Journal of Plant Growth Regulation - The growth and development of cold-season plants are susceptible to high temperature. Melatonin is a plant growth regulator with potential to improve plant... 相似文献
997.
Jin Xu Junfeng Shi Weiwei Tang Peng Jiang Muhong Guo Bin Zhang Ge Ma 《Journal of cellular biochemistry》2020,121(10):4142-4153
Receptor tyrosine kinase-like orphan receptor 2 (ROR2) is a tyrosine-protein kinase receptor highly implicated in the growth plate and cartilage development, which may be involved in epithelial-mesenchymal transition (EMT) in breast cancer (BC) cells. Although ROR2 is known to promote the migration of BC cells, the detailed mechanism of this event is still not clear. Here, we found that ROR2 expression was significantly increased in BC lymphatic metastatic tissue as well as BC samples compared to normal adjacent breast tissues. A higher expression of ROR2 in MDA-MB-231 and a lower expression of ROR2 in MCF-7 cells were observed. MDA-MB-231-siROR2 cells with ROR2 knockdown inhibited MDA-MB-231 cell invasion, migration, and clonal formation, while MCF-7-OvROR2 cells with overexpression showed the opposite results. The underlying mechanisms involved in ROR2-induced EMT in MDA-MB-231 and MCF-7 cells were further investigated. ROR2 may activate EMT progression in BC cells by altering MAPK kinase 3/6 (MKK3/6) expression. The expressions of transforming growth factor-β, matrix metalloproteinase-2 (MMP-2), and MMP-9, which were related to tumor cell invasion activities, were notably increased in MCF-7-OvROR2 cells. The EMT markers, including snail, N-cadherin, tissue inhibitor of metalloproteinases-1, and vimentin, were significantly upregulated in MCF-7-OvROR2 cells. On the contrary, E-cadherin was obviously reduced expressed in MCF-7-OvROR2 cells. ROR2 may regulate the malignant phenotype of BC cells possibly via activation of mitogen-activated protein kinase (MAPK)/p38 signaling pathway. Collectively, ROR2 promotes BC carcinogenesis by mediating the MAPK/p38 pathway, which is independent of Wnt5α. 相似文献
998.
Li Gao Yuanyuan Ma Xiting Li Liping Zhang Chi Zhang Qianying Chen Chuanjiang Zhao 《Journal of cellular biochemistry》2020,121(1):93-102
Porphyromonas gingivalis, as a major pathogen of periodontitis, could rapidly adhere to and invade host gingival epithelial cells (GECs) for the induction of infection. One ATP-binding cassette (ABC) transporter gene was found to be upregulated during this infection process, however, the molecular mechanisms remain unclear. In this study, we systemically investigated the messenger RNA level changes of all ABC transporter family genes in P. gingivalis while being internalized within GECs by real-time polymerase chain reaction. We identified that two ABC transporter genes, PG_RS04465 (PG1010) and PG_RS07320 (PG1665), were significantly increased in P. gingivalis after coculturing with GECs. Mutant strains with knockout (KO) of these two genes were generated by homogenous recombination. PG_RS04465 and PG_RS07320 KO mutants showed no change in the growth of bacteria per se. Knockdown of PG_RS07320, but not PG_RS04465, caused decreased endotoxin level in the bacteria. In contrast, both mutant strains showed decreased Arg- and Lys-gingipains activities, with significantly reduced adhesion and invasion capabilities. Secreted interleukin-1β (IL-1β) and IL-6 levels in GECs cocultured with PG_RS04465 or PG_RS07320 KO mutants were also decreased, whereas, only the cells cocultured with PG_RS07320 KO mutants showed significant decrease. In addition, virulence study using mouse revealed that both KO mutant strains infection caused less mouse death than wild-type strains, showing reduced virulence of two KO strains. These results indicated that ABC transporter genes PG_RS04465 and PG_RS07320 are positive regulators of the virulence of P. gingivalis. 相似文献
999.
Xiang Ma Jiaxi Feng Ming Lu Wenjuan Tang Jianbo Han XiaGang Luo Qinghong Zhao Li Yang 《Journal of cellular biochemistry》2020,121(2):1911-1922
In spite of the achievement in treatment, the gastric cancer (GC) mortality still remains high. MicroRNAs (miRNAs) are a group of small noncoding RNAs that play a crucial part in tumor progression. In this study, we explored the expression and function of microRNA-501-5p (miR-501-5p) in GC cell lines. Quantitative real-time polymerase chain reaction assay results suggested that miR-501-5p was significantly upregulated in GC tissues and cell lines. And, the Cell Counting Kit-8 colony formation and cell migration assay results showed that the downregulation of miR-501-5p decreased GC cell proliferation and migration. Besides that, we found that GC cell cycle was arrested in G2 phase and cell apoptosis rate was increased by silencing the expression of miR-501-5p in GC cell lines using the flow cytometry. We also found that miR-501-5p could directly target lysophosphatidic acid receptor 1 (LPAR1) and negatively regulate LPAR1 expression in GC cell lines by performing dual-luciferase reporter gene assay and Western blot analysis. And, LPAR1 was significantly downregulated in GC tissues and inversely correlated with miR-501-5p expression. Furthermore, LPAR1 downregulation promoted cell proliferation and migration, which were attenuated by cotransfection of miR-501-5p inhibitor in GC cells. In conclusion, miR-501-5p can promote GC cell proliferation and migration by targeting and downregulating LPAR1. miR-501-5p/LPAR1 may become a potential therapeutic target for GC treatment. 相似文献
1000.
Dingsheng Liu Hong Zhang Jinchun Cong Mingming Cui Mingxing Ma Fangyuan Zhang Huayi Sun Chunsheng Chen 《Journal of cellular biochemistry》2020,121(2):1923-1933
Long noncoding RNAs (lncRNAs) are found to be aberrantly expressed and pose significant impacts in colorectal cancer (CRC), the most prevalent type malignancy in the gastrointestinal tract. This study aimed to find out the regulation of lncRNA EIF3J antisense RNA 1 (EIF3J-AS1) on CRC progression. Expressions of EIF3J-AS1, microRNA-3163 (miR-3163), and Yes-associated protein 1 (YAP1) in tissues and cells were evaluated by real-time quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis. Association of EIF3J-AS1 with CRC prognosis was analyzed through the online bioinformatics tool GEPIA. The biological function of EIF3J-AS1 in CRC was investigated by Cell Counting Kit-8, colony formation, caspase-3 activity, and TUNEL staining. Competitive endogenous RNA (ceRNA) network of EIF3J-AS1/miR-3163/YAP1 was determined by luciferase reporter and RNA immunoprecipitation assays. Results showed that EIF3J-AS1 was upregulated in CRC tissues and cell lines, indicating poor prognosis of CRC patients. The silence of EIF3J-AS1 led to reduced proliferation and facilitated apoptosis of CRC cells. Mechanistcally, EIF3J-AS1 was upregulated by cAMP-response element-binding protein-binding protein-mediated histone H3 on lysine 27 acetylation (H3K27ac) at the promoter region, and EIF3J-AS1 upregulated YAP1 expression through sponging miR-3163 in CRC cells. In conclusion, we first found that H3K27 acetylation-induced lncRNA EIF3J-AS1 improved proliferation and impeded apoptosis of colorectal cancer through the miR-3163/YAP1 axis, which might potentially provide a novel molecular-targeted strategy for CRC treatment. 相似文献