首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1381篇
  免费   90篇
  国内免费   102篇
林业   27篇
农学   105篇
基础科学   3篇
  119篇
综合类   400篇
农作物   108篇
水产渔业   70篇
畜牧兽医   303篇
园艺   323篇
植物保护   115篇
  2024年   3篇
  2023年   26篇
  2022年   17篇
  2021年   37篇
  2020年   46篇
  2019年   55篇
  2018年   49篇
  2017年   56篇
  2016年   97篇
  2015年   79篇
  2014年   75篇
  2013年   83篇
  2012年   102篇
  2011年   122篇
  2010年   84篇
  2009年   74篇
  2008年   67篇
  2007年   98篇
  2006年   66篇
  2005年   53篇
  2004年   51篇
  2003年   35篇
  2002年   21篇
  2001年   24篇
  2000年   20篇
  1999年   15篇
  1998年   21篇
  1997年   13篇
  1996年   17篇
  1995年   13篇
  1994年   6篇
  1993年   14篇
  1992年   6篇
  1991年   5篇
  1990年   4篇
  1989年   4篇
  1988年   5篇
  1987年   2篇
  1986年   1篇
  1983年   1篇
  1981年   2篇
  1977年   2篇
  1963年   1篇
  1955年   1篇
排序方式: 共有1573条查询结果,搜索用时 296 毫秒
11.
Protein kinase C pathway is an important intracellular signal transduction pathway. A growing number of evidences showes that activation of PKC influences endothelial cell permeability. In this review, we briefly summarize the effects and regulating pathways of protein kinase C in modulation of vascular endothelium permeability.  相似文献   
12.
13.
AIM: In order to study the relationship between the ERK and p38 MAPK activation and the protection of 11, 12-epoxyeicosatrienoic acid (11, 12-EET) and ischemia preconditioning (IP), the effects of 11, 12-EET and ischemic preconditioning on phosphorylated ERK and p38 MAPK during ischemia and reperfusion in rat myocardium were examined. METHODS: The rat heart was subjected to ischemia for 5 min by ligating the left anterior descending coronary artery followed by reperfusion for 5 min (two times) to undergo ischemia preconditioning. The rats were divided into 5 groups: (1) control; (2) sham group; (3) ischemia/reperfusion (I/R) group, in which the rat heart suffered from 60 min ischemia followed by 30 min reperfusion; (4) IP plus I/R group; (5) EET plus I/R group, in which 6.28×10-8 mol/L 11, 12-EET was injected intravenously 20 min before I/R. The heart function was examined, and phosphorylated ERK and p38 MAPK were detected by Western blot. RESULTS: At 30 min reperfusion, +dp/dtmax, -dp/dtmax and LVDP decreased significantly in I/R group compared with sham group, IP plus I/R group and EET plus I/R group; Phosphorylated ERK1/2 level was higher in I/R group than sham group, but was lower in I/R group than IP plus I/R group and EET plus I/R group; Phosphorylated p38 MAPK level was lower in control, sham, IP plus I/R and EET plus I/R group than I/R group. CONCLUSION: 11,12-EET protects rat heart against ischemia/reperfusion injury, the mechanism may be related to activation of ERK1/2 and inhibition of p38 MAPK.  相似文献   
14.
AIM: To investigate whether protein kinase C (PKC) is involved in the proliferation and the telomerase expression in human hepatocellular carcinoma cells. METHODS: Human hepatocellular carcinoma cells (BEL-7402) were treated with exogenous phorbol-12-myristate-13-acetate (PMA, PKC activator) and staurosporine (SP, PKC inhibitor) for 48 hours. The techniques of cell culture and the telomeric repeat amplification protocol silver staining in combination with computer image scanning system in vitro were used to observe the variations of the growth and the telomerase expression. RESULTS: The proliferative potential of BEL-7402 cells was decreased by the action of PMA as well as SP, and the telomerase expression was also inhibited by PMA and SP. CONCLUSION: Our findings suggest that the proliferation of human hepatocellular carcinoma cells and the telomerase expression may be related to PKC.  相似文献   
15.
为探明BWMK1介导的信号传导途径,采用酵母双杂交系统,构建水稻稻瘟病菌诱导后的cDNA文库,以BWMK1为诱饵,对文库进行筛选,通过验证、测序和基因编码分析,获得了7个BWMK1互作基因BWIP1~BWIP7,分别位于水稻基因组第12、2、3、10、6、4、5染色体上;7个互作基因中,除BWlP2和BWIP7未找到同...  相似文献   
16.
保加利亚乳杆菌凭借其微生物特性和效能优异等特点成为当下产乳酸最重要的微生物菌株之一。乙酸是保加利亚乳杆菌代谢乳酸最主要的副产物,它的大量生成降低葡萄糖的代谢利用率,并且消耗了能量。乙酸激酶是控制乙酸生成的关键酶,敲除乙酸激酶基因,理论上可以阻断戊糖磷酸途径中乙酸的生成,从而优化代谢途径提高葡萄糖代谢乳酸的利用率。研究以Lactobacillus delbrueckii subsp.bulgaricus ATCC 11842公布的乙酸激酶基因ack序列设计引物,以保加利亚乳杆菌基因组DNA为模板,PCR克隆出ack上下游片段,利用重叠PCR技术将上下游片段拼接在一起,并连入具有温敏性的p Ghost4载体。  相似文献   
17.
通过Solexa技术和比较基因组学方法鉴定霜霉威胁迫下黄瓜果实差异表达基因,筛选黄瓜低霜霉威残留性相关基因SDH。研究利用PCR克隆获得SDH基因全长,命名为Cs SDH。构建亚细胞定位表达载体,利用农杆菌浸润法注射烟草叶片后激光共聚焦显微镜下观察;分别用荧光定量RT-PCR方法和酶联免疫法研究高、低农残品系D9320和D0351中Cs SDH基因在农药霜霉威处理后,不同时间点、不同组织部位时空表达特征和琥珀酸脱氢酶活性。结果表明,Cs SDH基因在烟草叶片细胞中被定位在细胞膜上。黄瓜低农残品种D0351中,Cs SDH基因在果实受霜霉威胁迫后反应迅速,主要在处理前期响应表达强烈,琥珀酸脱氢酶活性显著增加,且该基因表达量显著高于其在高农残品种D9320中表达量。Cs SDH果、叶中表达量较茎中高,且各组织部位表达量高低顺序稳定,为叶果茎。黄瓜高农残品种D9320中,Cs SDH基因表达量在0.5、1、3、12 h呈现上调表达,6、9 h基因表达量差异不显著,48 h出现上调表达高峰。说明克隆得到的Cs SDH基因属农药处理前期响应基因,且该基因可能在降低黄瓜农药残留过程中发挥重要作用。试验通过研究黄瓜琥珀酸脱氢酶基因(SDH)在霜霉威胁迫下表达情况,为挖掘黄瓜低农药残留性功能基因以及探明其作用分子机制奠定基础。  相似文献   
18.
Effects of water‐misting sprays with forced ventilation on post mortem glycolysis, adenosine monophosphate‐activated protein kinase (AMPK) and meat quality of broilers after transport during summer were investigated in the present paper. A total of 105 mixed‐sex Arbor Acres broilers were divided into three treatment groups: (i) 45 min transport without rest (T); (ii) 45 min transport with 1 h rest (TR); and (iii) 45 min transport with 15 min water‐misting sprays with forced ventilation and 45 min rest (TWFR). Each treatment consisted of five replicates with seven birds each. The results indicated that the water‐misting sprays with forced ventilation could mitigate the stress caused by transport under high temperature conditions during summer, which reduced the energy depletion in post mortem Pectoralis major (PM) muscle. This resulted in a higher energy status compared to the T group, which would decrease the expression of phosphorylation of AMPK (p‐AMPK). Furthermore, decreased the expression of p‐AMPK then slowed down the rate of glycolysis in post mortem PM muscle during the early post mortem period, which in turn lessened the negative effects caused by transport on meat quality. In conclusion, water‐misting sprays with forced ventilation may be a better method to control the incidence of the pale, soft and exudative meat in broilers.  相似文献   
19.
The Brucella mdh gene was successfully cloned and expressed in E. coli. The purified recombinant malate dehydrogenase protein (rMDH) was reactive to Brucella-positive bovine serum in the early stage, but not reactive in the middle or late stage, and was reactive to Brucella-positive mouse serum in the late stage, but not in the early or middle stage of infection. In addition, rMDH did not react with Brucella-negative bovine or mouse sera. These results suggest that rMDH has the potential for use as a specific antigen in serological diagnosis for early detection of bovine brucellosis.  相似文献   
20.
This retrospective case series evaluates survival outcome of 94 dogs with high metastatic risk mast cell tumours (MCT). Patients were treated with a cytotoxic chemotherapy protocol or the tyrosine kinase inhibitor masitinib, in the presence of gross disease or as an adjunct to surgical resection of the primary tumour. In patients presenting with metastatic disease, surgical resection of the primary tumour with adjunctive therapy with any chemotherapy incurred a significant survival advantage [median survival time (MST): 278 days] compared to patients receiving chemotherapy without surgical excision of the primary tumour (MST: 91 days, P < 0.0001). Patients with a surgically excised Patnaik grade II tumour and high Ki‐67 in the absence of metastatic disease treated with vinblastine and prednisolone showed a significantly longer survival (MST: 1946 days) than those treated with masitinib (MST: 369 days, P = 0.0037). Further prospective case‐controlled clinical trials of high‐risk MCTs are required to make precise evidence‐based treatment decisions for individual patients.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号