全文获取类型
收费全文 | 2917篇 |
免费 | 145篇 |
国内免费 | 338篇 |
专业分类
林业 | 103篇 |
农学 | 346篇 |
基础科学 | 19篇 |
127篇 | |
综合类 | 986篇 |
农作物 | 571篇 |
水产渔业 | 151篇 |
畜牧兽医 | 597篇 |
园艺 | 434篇 |
植物保护 | 66篇 |
出版年
2024年 | 13篇 |
2023年 | 26篇 |
2022年 | 51篇 |
2021年 | 76篇 |
2020年 | 85篇 |
2019年 | 96篇 |
2018年 | 49篇 |
2017年 | 92篇 |
2016年 | 121篇 |
2015年 | 110篇 |
2014年 | 132篇 |
2013年 | 150篇 |
2012年 | 191篇 |
2011年 | 217篇 |
2010年 | 155篇 |
2009年 | 216篇 |
2008年 | 208篇 |
2007年 | 236篇 |
2006年 | 168篇 |
2005年 | 104篇 |
2004年 | 122篇 |
2003年 | 100篇 |
2002年 | 74篇 |
2001年 | 73篇 |
2000年 | 64篇 |
1999年 | 50篇 |
1998年 | 51篇 |
1997年 | 57篇 |
1996年 | 45篇 |
1995年 | 45篇 |
1994年 | 42篇 |
1993年 | 32篇 |
1992年 | 25篇 |
1991年 | 26篇 |
1990年 | 40篇 |
1989年 | 22篇 |
1988年 | 9篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1963年 | 3篇 |
1956年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有3400条查询结果,搜索用时 15 毫秒
51.
玉米籽粒发育早期,代谢活动旺盛,细胞分裂与增大活跃,为后续贮藏物质的合成形成充足库容。为阐明籽粒早期发育的蛋白合成、积累与调控过程,本研究以夏玉米品种登海661为试验材料,在开花期人工饱和授粉后第3、第5、第10天取果穗中部籽粒,利用同位素标记相对定量(iTRAQ)技术分析其蛋白差异表达特性。玉米籽粒早期发育阶段总计鉴定及定量2639种蛋白,这些蛋白涉及多种生物过程与分子功能,其中代谢过程和分子过程是最主要的2个生物过程;催化活性和绑定功能是最主要的2个分子功能,这些生物过程与分子功能对籽粒早期发育具有重要作用。定量分析结果表明137种蛋白在籽粒发育早期显著差异表达,其功能涉及蛋白代谢、胁迫响应、细胞生长与分裂、碳水化合物与能量代谢、转运、次生物质代谢、淀粉合成、转录、油脂代谢、信号转导、氨基酸代谢等。其中,表达差异较大的是与蛋白代谢、胁迫响应、细胞生长与分裂以及碳水化合物与能量代谢相关的蛋白。表达模式聚类结果显示这些不同功能类别的蛋白协同表达,共同调控玉米籽粒的早期发育。 相似文献
52.
53.
54.
本实验采用穗离体培养的方法研究了不同培养温度对小麦蛋白质及其组分和小麦产量性状的影响.试验表明:在扬花前3天至乳熟期间,温度对小麦籽粒总蛋白质的含量影响不大,但对蛋白质组分影响较大,低温有利于清蛋白的形成,高温有利于醇溶蛋白和谷蛋白的形成;同时试验还表明低温条件下小麦茎杆总蛋白含量高于高温培养下的茎杆含量;不同培养温度对小麦结实率和粒重也有影响,小麦1.2小花和整穗可见花结实率随温度增高而上升,到20℃时达到最大,分别为96.36%和72.11%,百粒重随温度的升高而增大,呈线性相关,相关系数为0.974013.另外本试验还对受温度影响的13个指标进行了因子分析,分析结果表明13个指标可以压缩为3个因子,因子1可以命名为产量因子,决定总变异的48.045 4%,因子2和因子3可合称为蛋白质组分和粒重因子决定总变异的51.9546%. 相似文献
55.
菠萝锌指蛋白基因AcRCHY1的克隆与表达分析 总被引:1,自引:0,他引:1
根据植物C3HC4型兼CHY型锌指蛋白的功能保守区设计简并引物, 通过RT2PCR结合RACE
方法从菠萝(Ananas comosus L. Merr) 幼苗中克隆获得了一个新的菠萝锌指蛋白基因cDNA全长, 将其命名为AcRCHY1。该基因cDNA全长1 261 bp, 开放阅读框ORF为918 bp, 推测其编码一个含有306个氨基酸残基的多肽。AcRCHY1蛋白具有保守的C3HC4 (RING finger) 和CHY两个锌指结构域, 与其它植物锌指蛋白的同源性高达81%~91%。半定量RT-PCR分析表明, AcRCHY1 在菠萝中呈组成性表达, 在子房、花瓣和小花中的表达量明显高于根和叶; 低温、高盐、干旱和ABA等非生物胁迫处理后, AcRCHY1在叶片中的表达明显增强。因此, AcRCHY1蛋白可能与花器官生长发育的调控有关, 而且可能作为一个转录调控因子在菠萝响应低温、高盐和渗透胁迫过程中参与了依赖ABA的信号转导途径。 相似文献
56.
Protein content and properties in the seminal plasma of Atlantic halibut (Hippoglossus hippoglossus) were assayed using spectrophotometric and electrophoretic methods. The protein concentration ranged from 6.4 ± 3.1 to 19.4 ± 3.4 mg ml−1 and anti-proteolytic activity from 585.2 ± 104.6 to 2912.4 ± 367.4 U l−l. A high correlation between anti-proteolytic activity and protein concentration (r = 0.95), and between sperm concentration and osmolality was found (r = 0.92). There was a significant decrease in anti-proteolytic activity from the first to the second sampling, but not in
protein concentration. Anti-proteolytic activity and protein concentration were significantly affected by variations in individual
males. Electrophoresis revealed four anti-proteolytic bands and individual differences in bands of proteolytic activity, which
were subsequently characterized as metalloproteases and serine proteases. 相似文献
57.
AIM:To determine the relationship between ischemia, hypoxia and the production of vascular endothelial growth factor in rat myocardium and its basic mechanism. METHODS:(1) 28 Wistar rats were randomly divided into 4 groups: group A, normal control;group B, 1 day's acute myocardial infarction;group C, 3 day's acute myocardial infarction;group D, 7 day's acute myocardial infarction. (2) Rat cardiac myocytes cultured were primarily divided into some groups, hypoxia incubated 24 hours; PMA groups, hypoxia incubated 24 hours with PKC activator (PMA), A 0 ng/mL; B 10 ng/mL; C 100 ng/mL; D 1 000 ng/mL; Chelerythrine groups, hypoxia incubated 24 hours with PKC inhibitor (chelerythrine), A 0 nmol/L; B 10 nmol/L. (3) By computer scanned and quantitated, vascular endothelial growth factor (VEGF) protein was detected with immunohistochemical technique. RESULTS:The longer time of ischemia and hypoxia was, the higher the VEGF production.The relat ionship was found between the time of ischemia or hypoxia and the production of VEGF.The product ion of VEGF protein was further promoted by PMA with different concentrat ion, decreased by chelerythrine.CONCLUSION: Ischemia or hypoxia strongly stimulated the production of VEGF in myocardium, which played an important role in autoprotecting of ischemic or hypoxic myocardium. Hypoxia-induced PKC activation is one kind of basic mechanisms in this course. 相似文献
58.
MicroRNA-142-3p modulates atherosclerosis-associated endothelial cell apoptosis via targeting Rictor
AIM To investigate the role of microRNA-142-3p (miR-142-3p) in endothelial cell apoptosis during atherosclerosis (AS) and the underlying mechanism. METHODS Human aortic endothelial cells (HAECs) were treated with oxidized low-density lipoprotein (ox-LDL). The expression level of miR-142-3p was detected by RT-qPCR. Apoptosis was determined via flow cytometry (FCM) and caspase-3 activity assay. Prediction of the binding site between miR-142-3p and 3’-UTR of Rictor mRNA was performed by bioinformatics analysis and confirmed by dual-luciferase reporter assay. RESULTS The expression of miR-142-3p was substantially up-regulated during the ox-LDL-elicited apoptosis in HAECs (P <0.05,P <0.01). Forced expression of miR-142-3p exacerbated apoptosis in HAECs whereas inhibition of miR-142-3p partly alleviated apoptotic cell death mediated by ox-LDL. Further analysis identified Rictor as a direct target gene of miR-142-3p, and Rictor knock-down abolished the anti-apoptotic effect of miR-142-3p inhibitor. Moreover, the Akt/endothelial nitric oxide synthase (eNOS) signaling pathway was found to mediate the beneficial effect of miR-142-3p inhibitor on endothelial cells apoptosis. CONCLUSION Down-regulation of miR-142-3p inhibits endothelial cell apoptosis and atherosclerotic development by up-regulating the expression of Rictor and activating the Akt/eNOS signaling pathway. 相似文献
59.
AIM To investigate the mechanism of long noncoding RNA (lncRNA) FEZF1-AS1 regulating microRNA-363-3p (miR-363-3p) on the viability and apoptosis of lipopolysaocharide (LPS)-induced vascular endothelial cells. METHODS Human umbilical vein endothelial cells (HUVECs) were cultured in vitro . pcDNA-NC, pcDNA-FEZF1-AS1, anti-miR-NC, anti-miR-363-3p, miR-NC and miR-363-3p mimics were transfected into the HUVECs and LPS stimulation was applied for 24 h. RT-qPCR was used to detect the expression of FEZF1-AS1 and miR-363-3p. The cell viability was measured by MTT assay. The apoptotic rate was analyzed by flow cytometry. The dual-luciferase reporter experiment was used to verify the targeted regulation of FEZF1-AS1 and miR-363-3p. Western blot was used to determined the expression of cyclin D1, Ki67 and cleaved caspase-3. RESULTS Compared with control group, the expression level of FEZF1-AS1 in LPS group was significantly reduced (P <0.05), and the expression level of miR-363-3p was significantly increased (P <0.05). Compared with pcDNA-NC+LPS group, the cell viability in pcDNA-FEZF1-AS1+LPS group was significantly increased (P <0.05), the apoptotic rate was significantly reduced (P <0.05), the protein levels of cyclin D1 and Ki67 were significantly increased (P <0.05), and the protein level of cleaved caspase-3 was significantly reduced (P <0.05). Compared with anti-miR-NC+LPS group, the cell viability in anti-miR-363-3p+LPS group was significantly increased (P <0.05), the apoptotic rate was significantly reduced (P <0.05), the protein levels of cyclin D1 and Ki67 were significantly increased (P <0.05), and the protein level of cleaved caspase-3 was significantly reduced (P <0.05). Dual-luciferase reporter experiment confirmed that FEZF1-AS1 targeted miR-363-3p. Compared with miR-NC+pcDNA-FEZF1-AS1+LPS group, the cell viability in miR-363-3p+pcDNA-FEZF1-AS1+LPS group was significantly reduced (P <0.05), the apoptotic rate was significantly increased (P <0.05), the protein levels of cyclin D1 and Ki67 were significantly reduced (P <0.05), and the protein level of cleaved caspase-3 was significantly increased (P <0.05). CONCLUSION Over-expression of FEZF1-AS1 promotes the viability and inhibits apoptosis of LPS induced vascular endothelial cells by inhibiting the expression of miR-363-3p. 相似文献
60.
草菇低温诱导蛋白的初步研究 总被引:4,自引:2,他引:2
低温诱导草菇(Volvariella volvacea)菌丝体一时间后,发现草菇在低温胁迫中产生了新的可溶性蛋白质。应用电泳分离制备技术,分离纯化了草菇菌丝体中的一个低温诱导蛋白。 相似文献