全文获取类型
收费全文 | 10115篇 |
免费 | 528篇 |
国内免费 | 784篇 |
专业分类
林业 | 652篇 |
农学 | 740篇 |
基础科学 | 466篇 |
1190篇 | |
综合类 | 3502篇 |
农作物 | 639篇 |
水产渔业 | 572篇 |
畜牧兽医 | 2100篇 |
园艺 | 981篇 |
植物保护 | 585篇 |
出版年
2024年 | 51篇 |
2023年 | 147篇 |
2022年 | 306篇 |
2021年 | 357篇 |
2020年 | 384篇 |
2019年 | 500篇 |
2018年 | 310篇 |
2017年 | 445篇 |
2016年 | 515篇 |
2015年 | 477篇 |
2014年 | 509篇 |
2013年 | 567篇 |
2012年 | 763篇 |
2011年 | 872篇 |
2010年 | 655篇 |
2009年 | 609篇 |
2008年 | 618篇 |
2007年 | 658篇 |
2006年 | 529篇 |
2005年 | 378篇 |
2004年 | 286篇 |
2003年 | 242篇 |
2002年 | 187篇 |
2001年 | 157篇 |
2000年 | 156篇 |
1999年 | 128篇 |
1998年 | 85篇 |
1997年 | 87篇 |
1996年 | 64篇 |
1995年 | 67篇 |
1994年 | 56篇 |
1993年 | 51篇 |
1992年 | 40篇 |
1991年 | 33篇 |
1990年 | 28篇 |
1989年 | 22篇 |
1988年 | 15篇 |
1987年 | 15篇 |
1986年 | 13篇 |
1985年 | 12篇 |
1984年 | 2篇 |
1983年 | 6篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1973年 | 1篇 |
1956年 | 4篇 |
1955年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
151.
152.
The aim of the present study was to evaluate the impact of dietary fatty acids (FA) during the weaning period on expression of genes involved in the oxidation and metabolism of FA (peroxisome proliferator-activated receptor (PPAR-), stearoyl-CoA-desaturase (SCD), Δ6-desaturase (D6D), acetyl CoA carboxylase (ACC) and fatty acid synthase (FAS)). Liver samples were obtained from littermates, either on day 28 of age just before weaning, or at day 56 after the 4 weeks ad lib. provision of 5% of either animal fat, fish oil or sunflower oil. In conclusion, genes involved in the regulation of FA conversion (SCD, D6D) were influenced by the n-6 to n-3 ratio, whereas the FA oxidation, as indicated by the expression of PPAR-, was highly likely regulated by the hepatic ratio between mono- and poly-unsaturated FA. Furthermore, weaning and/or age affected the hepatic expression of genes involved in FA synthesis and conversion, but not the expression of PPAR-. 相似文献
153.
Akinori Hirashima Manabu Matsushita Kentaro Nakazono Morifusa Eto 《Pesticide biochemistry and physiology》2006,85(1):15-20
Effects of 1-arylimidazole-2(3H)-thiones (AITs) and 1-(substituted benzyl)imidazole-2(3H)-thiones (BITs) were tested on progeny formation in Drosophila melanogaster. Some AITs showed inhibitory activities at laying eggs and delayed eclosion by 1 day. The inhibitory activity was nullified by adding octopamine (OA) or noradrenaline (NA) to the medium for progeny formation in D. melanogaster. The effect of AIT on the contents of OA and NA was analyzed in adults of D. melanogaster by high-performance liquid chromatography with electrochemical detection. Flies fed with AIT decreased OA and NA levels and increased TA content. Taken together, the inhibitory activity of AIT could be due to inhibition of tyramine β-hydroxylase and dopamine β-hydroxylase. 相似文献
154.
AIM:To investigate the effect of protein kinase C on resistin expression in 3T3-L1 adipocytes.METHODS:The differentiated 3T3-L1 adipocytes were incubated with 50 nmol/L phorbol 12-myristate 13-acetate (PMA) or 5 μmol/L Ro-31-8220 for 24 h.Expression of resistin mRNA was detected by RT-PCR and expression of resistin protein was detected by Western blotting.RESULTS:Compared with control,PMA increased the expression of resistin mRNA and protein in 3T3-L1 adipocytes significantly (P<0.01),while Ro-31-8220 decreased the expression of resistin mRNA and protein in 3T3-L1 adipocytes obviously (P<0.01).CONCLUSION:Protein kinase C signal pathway may regulate resistin expression in 3T3-L1 adipocytes. 相似文献
155.
156.
Shoot tips excised from in vitro cultured plants of Dianthus caryophyllus L. (cv. Pallas, cv. Pink Candy and cv. Wanessa) were successfully cryopreserved using an encapsulation-vitrification method. Shoot tips (2–3 mm in length) were encapsulated in sodium alginate, precultured on liquid Murashige and Skoog (1962) medium supplemented with various sucrose concentrations (0.25, 0.5, 0.75, 1.0 M) for 24 h or 48 h and dehydrated with the vitrification solution PVS2 (up to 4 h) at 24 °C or 0 °C prior to direct immersion in liquid nitrogen (−196 °C). A maximum of shoot regeneration from cryopreserved shoot tips was obtained with the following combinations: preculture in 0.5 M sucrose and 180 min dehydration treatment at 0 °C for cv. Pallas (60% shoot formation), or preculture in 0.75 M and 200 min dehydration at the same temperature for cv. Pink Candy (66.6% shoot formation) and cv. Wanessa (73% shoot formation). 相似文献
157.
AIM:To investigate the role of caspase 3 inhibitor Ac-DEVD-CHO in caspase 3 signaling pathway and NF-κB activation induced by 10-hydroxycamptothecin (HCPT) in human breast carcinoma cells. METHODS:The cell growth inhibition was measured by MTT assay. Agarose gel electrophoresis was performed for detecting cell apoptosis. Western blotting was used for determining protein expression. DIG-EMSA was conducted to measure the DNA-binding activation of NF-κB. RESULTS:Caspase 3 inhibitor Ac-DEVD-CHO attenuated HCPT-induced apoptosis in human breast carcinoma. Ac-DEVD-CHO also suppressed the degradation of caspase 3 and IκBα,and arrested the activation of NF-κB. CONCLUSION:Caspase 3 inhibitor Ac-DEVD-CHO regulates the activation of caspase 3 and NF-κB,and attenuates apoptosis in Bcap37 cell line induced by HCPT. 相似文献
158.
159.
干旱胁迫诱导苹果属植物细胞程序性死亡的研究 总被引:5,自引:0,他引:5
用聚乙二醇(polyethylene glycol, PEG6000) 对苹果属植物平邑甜茶(Malus hupehensis pampReld. ) 和新疆野苹果〔M. sieversii (Ledeb) Roem. 〕幼苗进行水分胁迫处理, 通过Southern杂交和Western杂交的方法检测胁迫条件下幼苗体内DNA Ladder及Caspase23蛋白酶。Southern杂交结果表明, 干旱处理后, 两种苹果的根和叶片中都有DNA Ladder产生; Western杂交结果显示, 在苹果的叶片中有杂交印迹,而根中没有。这说明干旱胁迫可以诱导两种苹果属植物发生细胞程序性死亡, 并且在细胞程序性死亡过程中叶片中都有类Caspase-3蛋白酶的产生。 相似文献
160.
赤霉素对君子兰花期调控的研究 总被引:2,自引:3,他引:2
应用赤霉素不同浓度和不同处理频率对君子兰品种"油匠"进行处理.结果表明:与对照相比各浓度赤霉素(GA3)处理对植株提高抽葶率、提早花期、促进叶生长都有明显作用.每天喷施1次200 mg/L赤霉素后植株的抽葶率高于其他处理,50 mg/L赤霉素可以明显促进君子兰的花葶生长.应用50mg/L和200mg/L赤霉素均可使君子兰提前21 d开花,经过50mg/L赤霉素处理后,花朵和果实数量多于其他处理. 相似文献