全文获取类型
收费全文 | 4940篇 |
免费 | 285篇 |
国内免费 | 357篇 |
专业分类
林业 | 455篇 |
农学 | 210篇 |
基础科学 | 193篇 |
373篇 | |
综合类 | 2639篇 |
农作物 | 307篇 |
水产渔业 | 141篇 |
畜牧兽医 | 716篇 |
园艺 | 346篇 |
植物保护 | 202篇 |
出版年
2024年 | 13篇 |
2023年 | 70篇 |
2022年 | 174篇 |
2021年 | 168篇 |
2020年 | 177篇 |
2019年 | 166篇 |
2018年 | 85篇 |
2017年 | 172篇 |
2016年 | 138篇 |
2015年 | 196篇 |
2014年 | 254篇 |
2013年 | 316篇 |
2012年 | 456篇 |
2011年 | 471篇 |
2010年 | 458篇 |
2009年 | 426篇 |
2008年 | 430篇 |
2007年 | 395篇 |
2006年 | 288篇 |
2005年 | 233篇 |
2004年 | 148篇 |
2003年 | 76篇 |
2002年 | 72篇 |
2001年 | 71篇 |
2000年 | 89篇 |
1999年 | 27篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1988年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1956年 | 1篇 |
1955年 | 2篇 |
排序方式: 共有5582条查询结果,搜索用时 31 毫秒
91.
92.
AIM:To determine the migration mode of host lymphocytes into the intestinal graft by analyzing different lymphoid compartments of the graft. METHODS:2, 4, 6 days after transplantation, murine intestinal grafts were harvested for histologic assessment. Lymphocytes were collected from mesenteric lymph nodes (MLN), Peyer’s patch (PP), lamina propria lymphocytes (LPL) and intraepithelial lymphocytes (IEL) in the graft for analyzing by cytometry. RESULTS:At the day 2 and day 4, no evidence of rejection in intestinal allograft was found, while the rejection signs were apparent at the 6th day. At day 2 and day 4, host lymphocytes had rapidly replaced donor cell in graft MLN and PP. The migration of host lymphocytes into the LPL and IEL was not as fast as MLN and PP, however, the near-total replacement took place at the 6th post transplant day. The host lymphocytes were activated at the early stage of recruitment into the graft. CONCLUSION:The rapid recruitment of recipient lymphocytes and early activation could be responsible for the formidable rejection of intestinal transplantation. 相似文献
93.
94.
AIM:To study the expression of telomerase inhibitor Pinx1 in acute leukemia cells and during the differentiation of acute promyelocytic leukemia cells,and to realize its effect on telomerase activity.METHODS:Realtime quantitative PCR with fluorescence probe hybridization was used to measure the expression of Pinx1 and hTERT mRNA in acute leukemia cells and during differentiation of NB4 cells induced by ATRA.The correlations between Pinx1 and hTERT expression were also analyzed.RESULTS:Pinx1 mRNA expression in acute leukemia samples (0.00312,5.42×10-4-0.024) was significantly higher than that in normal bone marrow mononuclear cells (7.89×10-4,0-0.00863,P<0.01).The expression of Pinx1 mRNA had significant positive correlation with hTERT mRNA expression (r=0.296,P<0.05).Pinx1 mRNA expression decreased during differentiation,its expression was positive correlated with hTERT mRNA expression (r=0.900,P<0.05).CONCLUSIONS:As an inhibitor of telomerase,however,Pinx1 also had the same direction of regulation with telomerase activity in acute leukemia cells,suggesting its expression variation may be a subsequent reaction induced by that of hTERT to stabilize telomerase activity.The exact mechanisms remained to be verified. 相似文献
95.
96.
97.
98.
99.
从狂犬病病毒CVS毒株致死的小鼠脑组织中提取总RNA,通过RT-PCR获得G基因;以pMD18-T-α质粒为模板,PCR扩增得到IFN-α基因.两个基因和pIRES真核表达载体分别双酶切,连接构建P IRES-G/IFN-α,经PCR、双酶切鉴定和测序证明载体构建成功.测得的G基因序列长1 575 bp,与CVS株G基因氨基酸同源性为98.5%;IFN-α序列长为570 bp,与GenBank中登录号为NM 001017411的IFN-α基因氨基酸同源性为91.6%. 相似文献
100.