全文获取类型
收费全文 | 4703篇 |
免费 | 233篇 |
国内免费 | 577篇 |
专业分类
林业 | 119篇 |
农学 | 511篇 |
基础科学 | 66篇 |
282篇 | |
综合类 | 1725篇 |
农作物 | 232篇 |
水产渔业 | 188篇 |
畜牧兽医 | 2080篇 |
园艺 | 216篇 |
植物保护 | 94篇 |
出版年
2024年 | 27篇 |
2023年 | 74篇 |
2022年 | 138篇 |
2021年 | 219篇 |
2020年 | 189篇 |
2019年 | 194篇 |
2018年 | 118篇 |
2017年 | 167篇 |
2016年 | 168篇 |
2015年 | 197篇 |
2014年 | 237篇 |
2013年 | 228篇 |
2012年 | 374篇 |
2011年 | 391篇 |
2010年 | 296篇 |
2009年 | 314篇 |
2008年 | 269篇 |
2007年 | 273篇 |
2006年 | 254篇 |
2005年 | 179篇 |
2004年 | 150篇 |
2003年 | 139篇 |
2002年 | 94篇 |
2001年 | 86篇 |
2000年 | 68篇 |
1999年 | 71篇 |
1998年 | 56篇 |
1997年 | 44篇 |
1996年 | 55篇 |
1995年 | 38篇 |
1994年 | 59篇 |
1993年 | 40篇 |
1992年 | 37篇 |
1991年 | 56篇 |
1990年 | 33篇 |
1989年 | 37篇 |
1988年 | 30篇 |
1987年 | 25篇 |
1986年 | 14篇 |
1985年 | 6篇 |
1984年 | 8篇 |
1983年 | 3篇 |
1982年 | 8篇 |
1981年 | 7篇 |
1979年 | 11篇 |
1978年 | 6篇 |
1977年 | 8篇 |
1976年 | 6篇 |
1973年 | 2篇 |
1956年 | 7篇 |
排序方式: 共有5513条查询结果,搜索用时 0 毫秒
71.
72.
范良志 《畜牧兽医科学(电子版)》2021,(5):159-160
非洲猪瘟疫情已经成为制约养猪业发展的头号杀手,生猪稳产保供任务引起高度重视,因此,防控非洲猪瘟疫情是各级政府和养猪企业的重点工作之一,该文主要论述规模化猪场非洲猪瘟防控措施。 相似文献
73.
74.
75.
76.
Andrew Plant Achim Harder Norbert Mencke Heinz-Jürgen Bertram 《Pest management science》1996,48(4):351-358
7-Hydroxy-5-oxo-5H-thieno[3,2-b]pyran-6-carboxanilides and -6-thio-carboxanilides represent a novel series of anthelmintic compounds, with broad-spectrum activity against important parasitic nematodes in sheep and dogs. In particular, an improved efficacy against Trichostrongylus colubriformis in sheep over the related 3-carbamoyl-4-hydroxycoumarins has been noted. New synthetic routes to the key intermediate, 7-hydroxythieno[3,2-b]pyran-5-one, have been developed. 相似文献
77.
目的:研究二甲苯对实验人员外周血淋巴细胞染色体畸变的影响.方法:外周血培养制备染色体标本,分析外周血淋巴细胞染色体畸变.结果:二甲苯接触组的染色体数目畸变细胞率(11.3%)高于对照组(6.8%)(P<0.05);结构畸变细胞率(包括裂隙)(3.57%)高于对照组(2.6%)(P<0.05)并且呈剂量效应关系;接触组的未成熟着丝粒分离细胞率(1.85%)与对照组(1.34%)相比无显著差异(P>0.05).结论:二甲苯接触导致外周血淋巴细胞染色体畸变增加;二甲苯接触是否诱导未成熟着丝粒分离有待进一步深入研究. 相似文献
78.
Allysa L. Cole Natalie M. Kirk Leyi Wang Chien-Che Hung Jonathan P. Samuelson 《Journal of veterinary diagnostic investigation》2022,34(1):116
Two aborted Chester White pig fetuses were presented to a veterinary diagnostic laboratory in Illinois. Postmortem examination identified no gross abnormalities. Histologic evaluation revealed multifocal necrosis of chorionic epithelial cells, coalescing areas of mineralization in the placenta, and focal accumulations of viable and degenerate neutrophils in the lung. Intra- and extracellular acid-fast bacilli were identified in the lesions in both the placenta and lungs. Bacterial culture of stomach contents yielded heavy growth of Mycobacterium fortuitum, a rapidly growing nontuberculous mycobacterium (NTM), which was further confirmed through whole-genome sequencing. NTM are opportunistic pathogens commonly found in the soil and in contaminated water supplies. In animals, M. fortuitum is typically introduced through cutaneous wounds leading to infections limited to the skin, with systemic infection being uncommon. To our knowledge, abortion caused by M. fortuitum has not been reported previously. 相似文献
79.
染色体重排是一种可能导致DNA片段丢失、重复、易位和倒位的机制,从而改变基因组结构,为创造新的变异性状提供可能。植物染色体重排事件的准确鉴定有助于更深入地理解植物基因组的结构、功能及它们在植物演化和作物育种中的作用。该文深入探讨了植物染色体重排的基本概念,介绍了植物染色体重排的自然发生和人工诱导的技术方法,阐述了植物染色体重排的细胞生物学、分子遗传学和高通量测序鉴定方法。同时,系统总结了植物染色体重排技术在作物遗传育种中的应用,结合具体实践,着重强调了染色体重排技术在提高农作物的遗传多样性、改良农作物的重要性状、增强农作物的环境适应性等方面极具优越性。然而,目前染色体重排的发生概率较低,技术上仍存在挑战,需要更多精准的工具和策略来实现染色体片段的精准定位和重排。通过全面了解染色体重排及其相关技术,研究人员和育种家可以更好地利用植物基因组,为全球粮食安全和环境可持续发展提供创新解决方案。相关研究不仅为深入认识植物基因组提供新途径,也为未来创新作物育种奠定坚实基础。通过挖掘植物基因组的多样性和可塑性,染色体重排技术有望为培育高产、优质、多抗的农作物新品种提供更多可能性,对解决全球日益严峻的... 相似文献
80.
Yuan Meng-yi Chang Di Xie Tong-tong Sheng Xi-hui Feng Zi-yan Fu Bo-fan Li Qian-ru Liu Fang Guo Yong Ding Jin Wang Xiang-guo Ni He-min 《东北农业大学学报(英文版)》2021,28(1):61-74
WNT7A and β-catenin localisations and roles in regulating periimplantation ovine conceptus development under natural estrous conditions have been elaborated.However,their locations and expression patterns have not been reported under induction of oestrus.The localisation,expression and function of WNT7A and β-catenin in the uterine tissues of the early pregnant and non-pregnant sheep on days 10,12,14,16 and 18 following artificial induction of oestrus were investigated by means of in situ hybridisation,real-time RT-PCR,immuno-histochemistry and western blotting methods.WNT7A and β-catenin mRNA and protein were both restricted to the apical surfaces of the uterine luminal epithelium (LE) and glandular epithelium (GE).In pregnant sheep,protein localisation of WNT7A and β-catenin was observed both in the endometrial LE and GE.Their staining presented on day 10,increased between day 12 and day 16,and decreased on day 18.WNT7A and β-catenin mRNA and protein expression increased initially and then decreased from day 10 to day 18,peaking on day 16,and β-catenin reaching a peak on day 18 in the uterine tissues of pregnant sheep (p0.05).By contrast,no significant changes in WNT7A and β-catenin mRNA and protein expression levels were observed from day 10 to day 18 of the oestrus cycle in the uterine tissues of non-pregnant sheep (p0.05).Additionally,WNT7A and β-catenin mRNA and protein expression levels in the uterine tissues of the early pregnant sheep were significantly higher than those of non-pregnant sheep (p0.05).Treatment of endometrial epithelial cells with WNT7A increased the mRNA expressions of β-catenin,c-myc and Cyclin D1.These results provided an underlying mechanism of periimplantation ovine conceptus development under induction of oestrus. 相似文献