全文获取类型
收费全文 | 14683篇 |
免费 | 956篇 |
国内免费 | 1413篇 |
专业分类
林业 | 1492篇 |
农学 | 1287篇 |
基础科学 | 816篇 |
1916篇 | |
综合类 | 6302篇 |
农作物 | 1039篇 |
水产渔业 | 857篇 |
畜牧兽医 | 1661篇 |
园艺 | 1002篇 |
植物保护 | 680篇 |
出版年
2024年 | 94篇 |
2023年 | 263篇 |
2022年 | 581篇 |
2021年 | 661篇 |
2020年 | 595篇 |
2019年 | 627篇 |
2018年 | 429篇 |
2017年 | 654篇 |
2016年 | 424篇 |
2015年 | 709篇 |
2014年 | 714篇 |
2013年 | 822篇 |
2012年 | 1098篇 |
2011年 | 1119篇 |
2010年 | 1091篇 |
2009年 | 940篇 |
2008年 | 958篇 |
2007年 | 964篇 |
2006年 | 790篇 |
2005年 | 729篇 |
2004年 | 372篇 |
2003年 | 275篇 |
2002年 | 265篇 |
2001年 | 275篇 |
2000年 | 269篇 |
1999年 | 202篇 |
1998年 | 161篇 |
1997年 | 140篇 |
1996年 | 100篇 |
1995年 | 123篇 |
1994年 | 106篇 |
1993年 | 103篇 |
1992年 | 81篇 |
1991年 | 62篇 |
1990年 | 51篇 |
1989年 | 49篇 |
1988年 | 41篇 |
1987年 | 28篇 |
1986年 | 18篇 |
1985年 | 7篇 |
1984年 | 4篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 8篇 |
1980年 | 4篇 |
1974年 | 4篇 |
1971年 | 3篇 |
1969年 | 3篇 |
1964年 | 5篇 |
1956年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
AIM and METHODS:To analysis the factor that involved in renal carcinogenesis, we used the bait gene AK001518 to screen GenBank. To understand the relationship between cell cycle related gene(CCRG) and p15, we did RT-PCR and Northern Blot experiments. Then we examined CCRG expression level in renal carcinogenesis. RESULTS:Gained a function unknown gene CCRG that was 67% a mino acid identical with the gene AK001518 that was regulated by p15. It was shown that the CCRG mRNA was dramatically decreased when p15 gene was over-expressed. CCRG expression level was much higher in tumor tissues and cells than normal tissues and cells. CONCLUSION:The novel gene CCRG expressed highly in the renal carcinoma, which might play a significant role in the renal carcinogenesis. 相似文献
32.
ZHOU Yan-bin YE Ren-gao XIE Can-mao XU Han-shi GUAN Wei-ming YANG Xiao YANG Nian-sheng 《园艺学报》2003,19(9):1221-1223
AIM:To investigate the role of CD134 (OX40) and NF-κB in the pathogenesis of lupus nephritis (LN).METHODS:Renal in situ CD134 and NF-κB expression were examined in 40 biopsy specimens from LN patients by immunohistochemistry and microwave-based immunohistochemistry, respectively. The relationship between expression of CD134 and NF-κB was analyzed.RESULTS:The expression of glomerular and tubular CD134 and NF-κB in LN were higher than that in normal control, especially in class Ⅳ LN, where there was intense staining of endothelial cell, distal tubules, and interstitial mononuclear cell. The CD134 expression of glomerular and tubular was closely related to NF-κB expression, respectively (r=0.5542, P<0.05;r=0.6279, P<0.05). CONCLUSIONS:The abnormal expression of costimulatory molecule CD134 was well evidenced in LN. Strong expression of renal in situ NF-κB was likely mediated by CD134 signal pathway, which may play an important role in the pathogenesis of LN. 相似文献
33.
34.
35.
36.
37.
AIM: To observe the expression of undulin (Un) in liver tissue and to clarify the diagnostic significance of serum Un in experimental rat liver fibrosis. METHODS: Rat liver fibrosis was induced by carbon tetrachloride. The expression of Un in liver tissue was detected by immunohistochemical method. Serum Un levels was measured by enzyme immunoassay. RESULTS: Expression of Un increased in fibrotic liver than normal liver, and it was mainly distributed in portal tract stroma, central veins and fibrotic septa in fibrotic liver. Also, the level of serum Un was significantly higher in fibrotic liver than normal liver. CONCLUSION: These data suggest that Un should be a component of the hepatic extracellar matrix, and its expression could be increased greatly in fibrotic rat liver. Serum Un levels may be used as an indicator in liver fibrosis diagnosis. 相似文献
38.
39.
40.