全文获取类型
收费全文 | 51985篇 |
免费 | 3242篇 |
国内免费 | 5030篇 |
专业分类
林业 | 3308篇 |
农学 | 2791篇 |
基础科学 | 2725篇 |
5284篇 | |
综合类 | 25127篇 |
农作物 | 3566篇 |
水产渔业 | 1698篇 |
畜牧兽医 | 9166篇 |
园艺 | 3995篇 |
植物保护 | 2597篇 |
出版年
2024年 | 339篇 |
2023年 | 1169篇 |
2022年 | 2676篇 |
2021年 | 2458篇 |
2020年 | 2283篇 |
2019年 | 2323篇 |
2018年 | 1694篇 |
2017年 | 2604篇 |
2016年 | 1696篇 |
2015年 | 2623篇 |
2014年 | 2739篇 |
2013年 | 3176篇 |
2012年 | 4494篇 |
2011年 | 4546篇 |
2010年 | 4395篇 |
2009年 | 3889篇 |
2008年 | 3980篇 |
2007年 | 3445篇 |
2006年 | 2700篇 |
2005年 | 2085篇 |
2004年 | 1403篇 |
2003年 | 787篇 |
2002年 | 836篇 |
2001年 | 774篇 |
2000年 | 743篇 |
1999年 | 254篇 |
1998年 | 19篇 |
1997年 | 11篇 |
1996年 | 4篇 |
1995年 | 16篇 |
1994年 | 9篇 |
1993年 | 8篇 |
1992年 | 9篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1981年 | 6篇 |
1962年 | 10篇 |
1956年 | 25篇 |
1955年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
AIM: To investigate the activation of nuclear factor κB (NF-κB) induced by lipopolysaccharides (LPS) in rat alveolar macrophages (AMs) and its regulatory role in tumor necrosis factor (TNF-α) secretion. METHODS: The dynamic activity changes of NF-κB induced by LPS were determined with electrophoretic mobility shift assay (EMSA). Antisense oligonucleotides of NF-κB subunit (p65) were transfected into AMs prior to LPS stimulation. The effect of antisense oligonucleotide transfection on expressions of p65 and TNF-α in supernatant were measured with Western blotting and enzyme linked immunosorbent assay (ELISA), respectively.RESULTS: NF-κB activity increased markedly and reached its peak level at 4 h after LPS stimulation. After transfected with antisense oligonucleotides of NF-κB subunit (p65), expression of p65 and TNF-α in supernatant decreased markedly.CONCLUSION: NF-κB activity has a positive effect on regulating secretion of TNF-α in AMs induced by LPS. 相似文献
992.
993.
YIN Wei HUANG Yi-jun PI Rong-biao SU Xing-wen ZHAO Ling-zhi QIU Peng-xin YAN Guang-mei 《园艺学报》2007,23(11):2141-2146
AIM: To Screen and identify differentially expressed genes that involved in apoptosis model in rat cerebellar granule neurons (CGNs).METHODS: The rat cerebellar granule neurons were isolated and primarily cultured.Fluorescent differential display RT-PCR (FDD RT-PCR) was performed to screen differentially expressed ESTs in the apoptosis model of primarily cultured rat CGNs.ESTs were subcloned into pGEM-T EasyTM vector and then sequenced.Alignment assay in non-redunant database was applied for encoding information.Reverse Northern blotting was used to appraise the results from DDRT-PCR.RESULTS: 164 pieces of differentially expressed ESTs were obtained by FDDRT-PCR.17 of them were subcloned and sequenced.5 ESTs of 17 were confirmed to be positive results by reverse Northern blotting.CONCLUSION: DD-PCR is a rapid,simple-operation and sensitive method for screening differentially expressed genes,which would contribute to the molecular mechanisms of apoptosis/survive of CGNs. 相似文献
994.
995.
996.
997.
998.
应用于作物体细胞杂种鉴定的遗传标记方法 总被引:1,自引:0,他引:1
着重介绍了4类遗传标记方法的原理及特点,简要概述了其在作物体细胞杂种鉴定方面的应用进展. 相似文献
999.
HUANG Kai-hong WANG Ling-yun ZHAO Xiao-long LIU Jian- hua CHEN Ru-fu ZHU Zhao-hua 《园艺学报》2007,23(2):258-261
AIM:The characteristics of nanometer particles, which were prepared by the conjugation of anti-VEGF monoclonal antibodies and 5-fluorouracil-loaded polylactic acid nanometer particles (5-FU-NPs), were investigated for improving the anticancer activity of 5-FU. METHODS:The method of couple linkage of chemical bonds was used to prepare the 5-FU-NPs with VEGF antibody, then the appearance, distribution of particle diameter, releasing in vitro and the immunological activity were detected. RESULTS:The 5-FU-Ab-NPs appeared as regular globular, the average particle diameter was (202±23)nm. The 5-FU-Ab-NPs possessed the similar delayed release character of 5-FUs. More than 80% of the immmunogical activity were detected in conjugates-retained antibody by the immunological methods and electron microscopy. CONCLUSION:The 5-FU-Ab-NPs possess the similar delayed released activity to 5-FU-NPs and have double activity of immune targeting and delayed releasing, which may increase the local concentration of 5-FU. 相似文献
1000.
AIM:To investigate the mechanisms by which bilirubin inhibits acute lung injury (ALI). METHODS:30 female Wistar rats were divided into normal group, ALI group and bilirubin treatment group. ALI was induced by intravenous injection of LPS. The contents of OH-, H2O2 and O2· in the lung as well as the expression of caspase-3 in the lungs were investigated. RESULTS:(1) The contents of OH-, H2O2 and O2· in the lung homogenate and the expression of caspase-3 in the lungs in ALI group increased compared with those in normal group (P<0.05). (2) The contents of OH-, H2O2 and O2· in the lung homogenate and the expression of caspase-3 in the lungs in bilirubin treatment group increased compared with those in normal group, but decreased compared with those in ALI models (P<0.05). CONCLUSION:(1) Bilirubin was shown to be able to ameliorate apoptosis in ALI rats. (2) The increase in the contents of OH-, H2O2, O2· in ALI group indicated the development of oxidative lung injury, which was ameliorated by bilirubin. (3) Expression of caspase-3 confirmed that the model made by LPS was associated with apoptosis, which was reduced by bilirubin. 相似文献