全文获取类型
收费全文 | 15501篇 |
免费 | 1019篇 |
国内免费 | 680篇 |
专业分类
林业 | 1239篇 |
农学 | 915篇 |
基础科学 | 387篇 |
3120篇 | |
综合类 | 3392篇 |
农作物 | 890篇 |
水产渔业 | 1210篇 |
畜牧兽医 | 4299篇 |
园艺 | 658篇 |
植物保护 | 1090篇 |
出版年
2024年 | 60篇 |
2023年 | 249篇 |
2022年 | 472篇 |
2021年 | 639篇 |
2020年 | 601篇 |
2019年 | 600篇 |
2018年 | 649篇 |
2017年 | 748篇 |
2016年 | 674篇 |
2015年 | 725篇 |
2014年 | 774篇 |
2013年 | 1092篇 |
2012年 | 1313篇 |
2011年 | 1346篇 |
2010年 | 939篇 |
2009年 | 849篇 |
2008年 | 943篇 |
2007年 | 897篇 |
2006年 | 690篇 |
2005年 | 599篇 |
2004年 | 470篇 |
2003年 | 406篇 |
2002年 | 337篇 |
2001年 | 197篇 |
2000年 | 194篇 |
1999年 | 141篇 |
1998年 | 59篇 |
1997年 | 33篇 |
1996年 | 34篇 |
1995年 | 25篇 |
1994年 | 25篇 |
1993年 | 21篇 |
1992年 | 35篇 |
1991年 | 31篇 |
1990年 | 30篇 |
1989年 | 44篇 |
1988年 | 18篇 |
1987年 | 32篇 |
1986年 | 20篇 |
1985年 | 22篇 |
1984年 | 13篇 |
1983年 | 14篇 |
1981年 | 9篇 |
1980年 | 12篇 |
1977年 | 8篇 |
1976年 | 15篇 |
1972年 | 8篇 |
1968年 | 8篇 |
1967年 | 8篇 |
1966年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Juan Pablo Zoffoli Bernardo A. Latorre Paulina Naranjo 《Postharvest Biology and Technology》2009,51(2):183-192
Over 54,600 ha of table grapes (Vitis vinifera), mainly cvs. ‘Thompson Seedless’, ‘Flame Seedless’ and ‘Redglobe’, are planted in Chile. Almost the entire production is exported to the USA, Europe, Asia, or one of several Latin American countries, which typically requires 15–40 d of maritime transportation. During this period, several physical, physiological, and pathological factors cause table grape deterioration. Because berry size is the main quality factor in international markets, farmers often overuse the growth regulators, gibberellic acid (GA3) and forchlorfenuron (CPPU), in an effort to increase berry size. We examined the effect of preharvest growth regulators on seedless (‘Thompson Seedless’, and ‘Ruby Seedless’) and seeded (‘Redglobe’) table grape cultivars during cold (0 °C) storage plus a shelf life period of 3 d at 20 °C. The overuse of GA3, eight instead of two GA3 applications on Thompson Seedless, and the use of one GA3 application on Redglobe and ‘Ruby Seedless’, increased berry pedicel thickness and lowered cuticle content but induced shatter and predisposed grapes to gray mold caused by Botrytis cinerea. In contrast, CPPU increased berry pedicel thickness and cuticle content but did not increase shatter or gray mold incidence. Clusters that were subjected to overuse of combined GA3 and CPPU were highly sensitive to shatter, had the thickest pedicel, and developed a high gray mold incidence during cold storage. Hairline, a fine cracking developed during cold storage, was induced on ‘Thompson Seedless’ and ‘Ruby Seedless’ by growth regulators, but no hairline occurred on ‘Redglobe’ table grapes. Therefore, berry quality during cold storage is greatly influenced by growth regulator management in the vineyard. 相似文献
2.
A. T. Szabó 《Genetic Resources and Crop Evolution》2005,52(3):347
3.
4.
Mario Suwalsky Maritza BenitesBeryl Norris Carlos P Sotomayor 《Pesticide biochemistry and physiology》2003,77(2):44-53
The current study examines the acute effects of the organophosphorus pesticide chlorpyrifos on a sympathetic synapse of the frog Caudiverbera caudiverbera. Nerve stimulation was followed immediately by a transient increase in the short-circuit current (SCC) and in the potential difference (PD), which consisted of a rapid and then a slow component. Chlorpyrifos concentrations from 5 μM to 1.0 mM caused a dose-dependent block of both components to a 10% of their control values, which was reversed by washout. The pesticide blockade did not affect the skin response to noradrenaline. X-ray diffraction and fluorescence spectroscopy studies on membrane models showed marked phospholipid perturbation, which favors changes in ion channel conformation and interferes with receptor proteins, thus altering noradrenergic transmission and Cl− secretion in the mucous glands. The foregoing results may be interpreted as a reversible inhibition of the neuroepithelial synapse to nerve stimulation, possibly due to non-specific lip μd-protein perturbation, interference with synaptic transmission, and transient Cl− channel inactivation. 相似文献
5.
ZHOU Hua ZHANG Dai-fu SHAN Jiang SU Hai NIU Hui-yan WANG Juan YU Ping QI Wei-gang 《园艺学报》2004,20(12):2261-2264
AIM: To investigate the effects of angiotensin-converting enzyme inhibitors (ACEI), fosinopril, captopril and angiotensin II AT1 antagonists, valsartan on tissue factor (TF) expression on monocytes induced by lipopolysaccharide (LPS). METHODS: Mononuclear leukocytes from normal delivered female umbilical veins were incubated with bacterial LPS in presence or absence of different ACE inhibitors .At the end of incubation, the cells were disrupted by 3 freeze-thaw cycles. TF procoagulant activity was assessed by a one-stage clotting assay. RT-PCR was used to check TF mRNA expression, and GAPDH mRNA was used for parallel assay. RESULTS and CONCLUSION: The results showed that increased expression of TF mRNA induced by LPS was inhibited by fosinopril, captopril and valsartan, respectively, and the procoagualant activity of monocytes was also reduced. 相似文献
6.
Azarpajouh S. Marchewka J. Segura Correa J. C. Calderón Díaz J. A. 《Tropical animal health and production》2018,50(6):1343-1348
Tropical Animal Health and Production - The objective of this study was to compare hoof anatomy, hoof growth pattern, and hoof weight-bearing surface of six different Iranian sheep breeds to... 相似文献
7.
用紫外荧光法测定鞭角华扁叶蜂末龄幼虫及滞育预蛹血淋巴中多胺的动态.结果表明:鞭角华扁叶蜂血淋巴中含有8种多胺,其中腐胺(Put)、亚精胺(Spd)、精胺(Spm)、尸胺(Cad)为普遍存在的多胺,其发育的不同阶段,多胺的种类和含量均发生变化;在滞育预蛹的血淋巴中Spm一直保持较高的含量,并在整个滞育期间存在2个峰值;在滞育的前5个月中血淋巴中不存在Spd,之后Spd突然出现,且含量迅速升高;Cad的代谢较平稳,在化蛹前稍有下降;Put的含量除在滞育后3个月左右有较大的峰值外,其余阶段的含量均较高,并在化蛹前有升高的趋势.总之,多胺可能参与鞭角华扁叶蜂预蛹滞育过程. 相似文献
8.
9.
10.
本研究利用15对SSR 引物对161 份高粱属种质资源进行了遗传多样性分析。结果显示,15对引物共扩增出118条谱带,其中88条具有多态性,多态性比率(P)为75.21%;多态性信息含量(PIC值)变幅为0.612~0.806,平均为0.699。161份高粱属材料遗传相似性系数为0.636~0.977,平均基因多样性指数(H)为0.696,Shannon信息指数(I)为1.393。UPGMA聚类分析显示, 161 份高粱属材料在遗传相似系数(GS)为0.682处可分为3组;129份高粱和苏丹草材料在相似系数为0.671处可分为2组。表明SSR标记可以作为高粱属种间以及种内遗传分化分析的有力工具,被分析的高粱属种质材料具有较高的遗传多样性。 相似文献