全文获取类型
收费全文 | 17299篇 |
免费 | 1073篇 |
国内免费 | 1459篇 |
专业分类
林业 | 1016篇 |
农学 | 1552篇 |
基础科学 | 186篇 |
952篇 | |
综合类 | 5882篇 |
农作物 | 1343篇 |
水产渔业 | 637篇 |
畜牧兽医 | 4355篇 |
园艺 | 2950篇 |
植物保护 | 958篇 |
出版年
2024年 | 37篇 |
2023年 | 216篇 |
2022年 | 408篇 |
2021年 | 639篇 |
2020年 | 661篇 |
2019年 | 788篇 |
2018年 | 595篇 |
2017年 | 751篇 |
2016年 | 1038篇 |
2015年 | 963篇 |
2014年 | 1038篇 |
2013年 | 994篇 |
2012年 | 1338篇 |
2011年 | 1428篇 |
2010年 | 1154篇 |
2009年 | 1100篇 |
2008年 | 1042篇 |
2007年 | 1129篇 |
2006年 | 858篇 |
2005年 | 719篇 |
2004年 | 517篇 |
2003年 | 436篇 |
2002年 | 294篇 |
2001年 | 262篇 |
2000年 | 252篇 |
1999年 | 188篇 |
1998年 | 146篇 |
1997年 | 120篇 |
1996年 | 116篇 |
1995年 | 79篇 |
1994年 | 76篇 |
1993年 | 82篇 |
1992年 | 49篇 |
1991年 | 48篇 |
1990年 | 43篇 |
1989年 | 42篇 |
1988年 | 34篇 |
1987年 | 22篇 |
1986年 | 24篇 |
1985年 | 15篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 20篇 |
1980年 | 9篇 |
1979年 | 6篇 |
1976年 | 4篇 |
1962年 | 6篇 |
1956年 | 12篇 |
1955年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
月季切花乙烯受体ETR1 cDNA克隆及其序列分析* 总被引:6,自引:0,他引:6
根据乙烯受体基因ETR1 保守区设计引物, 分别以瓶插寿命差异显著的月季切花品种‘德克萨斯’和‘维亚蒂’为材料, 通过RT-PCR 从花瓣中扩增出了797 bp 的cDNA 片段, 它编码265 个氨基酸。测序和序列分析表明,‘德克萨斯’重组质粒中插入片段的核苷酸序列之间完全相同, 命名为pRT-ETR1。而‘维亚蒂’所获得的重组质粒中插入片段的核苷酸和氨基酸序列之间存在差异, 同源性分别为85. 2 %和92. 1 % , 分别命名为pRV-ETR1-V4 和pRV-ETR1-V5。pRV2 ETR12V5 的核苷酸和氨基酸序列与‘德克萨斯’pRT2 ETR1 的同源性均达99 %以上; pRV-ETR1-V4 中的核苷酸和氨基酸序列与‘德克萨斯’pRT-ETR1 的同源性分别为85. 0 %和92. 5 %。上述插入片段与桃、苹果、天竺葵、拟南芥等植物的ETR1相应区域高度同源, 其氨基酸同源性均大于90 %。 相似文献
112.
113.
114.
115.
116.
117.
118.
AIM:To establish the monoclonal antibody against human B lymphocyte stimulator (hBLyS) by DNA immunization and analyse its characterization. METHODS:The 858 bp DNA fragment of hBLyS was cloned into pcDNA3 plasmids. The cloned insert was identified by both sequence analysis and double digestion of the recombinant plasmid with restriction enzymesXho Iand EcoR I. After the splenocytes from BALB/c mice immunized with the recombinant plasmid of pcDNA3/hBLyS were fused with myeloma cells SP2/0,the hybridoma which can produce monoclonal antibodies against hBLyS were obtained. The specificity of anti-BLyS monoclonal antibody from hybridoma was verified by ELISA, Western blot and flow cytometry. RESULTS:The recombinant mammalian cell expression vector of pcDNA3/hBLyS was constructed,the sequence of the insert gene was identified to be the sequence encoding hBLy S antigen. The culture supernatants of hybridoma 9c10 were tested to be the monoclonal antibody with specificity against hBLyS on human peripheral blood CD3+T cell activated by hIFN-γ by ELISA,Western blot and flow cytometry.CONCLUSION:The monoclonal antibodies against hBLyS with high activity and specificity have been established successfully, and will be an useful tool in the studies of relationship between hBLyS and human autoimmunity diseases. 相似文献
119.
AIM: To study the effects of tetrandrine(Tet) and fructose-1, 6-diphosphate(FDP) on the elevated intrasynaptosomal [Ca2+]i induced by excitatory amino acids(EAA). METHODS: A rapid method for preparing synaptosomes was used, and intrasynaptosomal free calcium([Ca2+]i) was measured by using the fluorescent indicator quin-2. RESULTS: L-glutamate(Glu, 100 μmol/L), aspartate(Asp, 100 μmol·L-1), N-methy1-D-aspartate(100 μmol/L) and Glu(50 μmol/L) plus Asp(50 μmol/L) all elevated intrasynaptosomal [Ca2+]i in a dose-dependent manner. Pretreatment with Tet(10, 30, 60 μmol/L), FDP(15, 30, 75, 150 μmol/L), MK-801(10, 20 μmol/L) and Tet(15, 30 μmol/L) plus FDP(15, 30 μmol/L) all attenuated the increase in intrasynaptosomal [Ca2+]i induced by EAAs mentioned as above in a dose-dependent manner, and the effect of Tet plus FDP was most significant. CONCLUSION: Both Tet and FDP inhibited a rise in intrasynaptosomal [Ca2+]i induced by EAAs, which may be one of mechanisms that Tet and FDP pretect cerebral tissues against ischemia injury. 相似文献
120.
SHANG Zhan-ping HOU Zhong-chi ZHU Shi-gong JI Guo-yi WANG Jian-chun ZHAO Wan 《园艺学报》2002,18(12):1521-1523
AIM: To investigate the activity of interleukin-1β converting enzyme in transplanted intracerebral rat gliomas under angiotensin II-induced hypertension chemotherapy. METHODS: The brain tumor model was produced in Wistar rats by stereotaxic inoculation of C6 glioma cells (1×1012 /L). Tumor-bearing rats were treated with carmustine, teniposide and lisplatin (chemotherapy) during angiotensin II-induced hypertension. Then, the survival time of tumor-bearing rats, tumor blood flow, the concentration of drug, volume of gliomas and the activity of interleukin-1β converting enzyme in glioma were examined.RESULTS: The survival time of tumor-bearing rats was significantly longer in chemotherapy with angiotensin II-induced hypertension group than that of chemotherapy alone. In addition, regional tumor blood flow, the concentration of chemotherapeutic drug and the activity of interleukin -1β converting enzyme in transplanted rat gliomas were increased, while the volume of gliomas was decreased in hypertention chemotherapy group compared with chemotherapy alone. CONCLUSION: Chemotherapy with angiotensin II-induced hypertension has a enhancing effect on chemotherapy for improving the drug delivery to tumor tissue by a increased tumor blood flow and enhancing activity of interleukin -1β converting enzyme. 相似文献