全文获取类型
收费全文 | 15192篇 |
免费 | 1064篇 |
国内免费 | 1111篇 |
专业分类
林业 | 635篇 |
农学 | 858篇 |
基础科学 | 147篇 |
366篇 | |
综合类 | 4805篇 |
农作物 | 767篇 |
水产渔业 | 1059篇 |
畜牧兽医 | 6299篇 |
园艺 | 646篇 |
植物保护 | 1785篇 |
出版年
2024年 | 66篇 |
2023年 | 264篇 |
2022年 | 434篇 |
2021年 | 585篇 |
2020年 | 592篇 |
2019年 | 670篇 |
2018年 | 418篇 |
2017年 | 549篇 |
2016年 | 596篇 |
2015年 | 596篇 |
2014年 | 827篇 |
2013年 | 799篇 |
2012年 | 1024篇 |
2011年 | 1004篇 |
2010年 | 834篇 |
2009年 | 834篇 |
2008年 | 763篇 |
2007年 | 847篇 |
2006年 | 760篇 |
2005年 | 615篇 |
2004年 | 571篇 |
2003年 | 434篇 |
2002年 | 371篇 |
2001年 | 410篇 |
2000年 | 415篇 |
1999年 | 324篇 |
1998年 | 230篇 |
1997年 | 195篇 |
1996年 | 163篇 |
1995年 | 184篇 |
1994年 | 155篇 |
1993年 | 139篇 |
1992年 | 161篇 |
1991年 | 106篇 |
1990年 | 85篇 |
1989年 | 79篇 |
1988年 | 45篇 |
1987年 | 48篇 |
1986年 | 23篇 |
1985年 | 18篇 |
1984年 | 10篇 |
1983年 | 15篇 |
1982年 | 18篇 |
1981年 | 11篇 |
1980年 | 20篇 |
1979年 | 23篇 |
1978年 | 8篇 |
1976年 | 9篇 |
1956年 | 6篇 |
1955年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
假俭草作为一种优良的草坪草己广泛用于绿化之中,但病害会极大地影响草坪质量。为了对假俭草的病害防治提供依据,就其病害种类、症状、发病规律及防治措施进行了论述。 相似文献
992.
MB43活疫苗免疫效果及对鸡法氏囊组织操作的研究 总被引:1,自引:0,他引:1
本试验对鸡传染性法氏囊病(IBD)MB43活疫苗免疫后鸡的囊体比、新城疫血凝抑制(ND-HI)抗体效价及IBD AGP效价进行检测。结果表明,含有IBD高母抗试验鸡在17日龄免疫MB43活疫苗后,囊组织有不同程度的损伤;对正常免疫的ND-HI抗体效价无影响;试验鸡16天后IBD AGP阳性率为100%;21天攻毒保护率100%。 相似文献
993.
994.
番鸭新病——花肝病的研究:Ⅰ.分离毒的致病必及感染途径试验 总被引:4,自引:2,他引:2
番鸭花肝的是近年流行的一种新的番鸭疫病,其特征性病变是死亡番鸭的肝、脾、小肠等部位出现灰白色的坏死点,本文自广东省主要疫区分离到几株病毒,这些病毒在番鸭胚上可继代繁殖,其胚液可使番鸭妇病。不同途径感染试验表明该病毒通过肌肉注射、爪垫部注射、口服,同居感染均可使番鸭发病和死亡,并具有典型病变,分离毒不能使半番鸭,本地鸭,鸡发病。 相似文献
995.
将在不同时间、地域从传染性法氏囊病 (IBD)发病鸡群中获得的 15个IBDV株分别用SPF鸡、鸡胚和鸡胚成纤维细胞增殖 ,经氯仿处理后 ,采用聚乙二醇沉淀、超速离心和不连续蔗糖密度梯度离心的方法纯化病毒 ,检测表明 ,病毒主要分布于 40 %蔗糖层。对纯化病毒进行SDS_PAGE分析 ,结果显示 ,病毒结构蛋白VP2 在不同毒株表达量有较大差异。本实验为IB DV主要保护性抗原VP2 高表达疫苗的研究奠定了基础 相似文献
996.
Amory JR Mackenzie AM Eckersall PD Stear MJ Pearce GP 《Research in veterinary science》2007,83(3):428-435
Associations between serum concentrations of haptoglobin, pathological lung lesions indicative of Mycoplasma hyopneumoniae (EP) or Actinobacillus pleuropneumoniae (PL) infection at slaughter and previous rearing environment were investigated in 510 pigs (90-100 kg live weight) from 17 farms in England. Haptoglobin concentrations were significantly higher in pigs showing pathological signs of EP infection compared to those without signs of this disease (EP positive median 0.43 mg ml(-1) vs. EP negative median 0.26 mg ml(-1), p<0.01). However, there were no significant associations between serum haptoglobin concentrations and pathological signs of PL. The presence of solid partitions compared with barred or similar open partitions was associated with a decrease of 0.44 mg ml(-1) farm mean haptoglobin concentration, whilst an increase in pen size of 10 m(2) was associated with a decrease of 0.08 mg ml(-1) farm mean haptoglobin concentration. The findings indicate that pathological signs of EP were associated with increased serum haptoglobin at slaughter, which in turn was influenced by components of the farm environment. 相似文献
997.
Oligodeoxynucleotides containing unmethylated CpG motifs (CpG ODN) prevent development of T-helper type 2 (Th2) immune response and reverse established allergic responses in mouse models. However, little work on immune responses in piglets has been conducted in vivo. In this report, the ability of a porcine-specific CpG ODN to act as an immunostimulant and enhance immune responses of piglets to swine Pasteurella multocida living vaccine (SPML vaccine) was determined. The titre of IgG and IgG1/IgG2 isotype to SPML vaccine in serum, the proliferation of lymphocytes, SPML-specific interferon-gamma (IFN-gamma) and IL-6, TNF-alpha, IL-4 production of PBMCs in vitro and IFN-gamma, IL-6, TNF-alpha, IL-4, IL-10 in piglets serum were examined to identify the immune responses of the piglets. Immune responses of the piglets vaccinated with SPML and CpG ODN were significantly stronger than responses of piglets vaccinated with SPML alone. All these data summarized that immunostimulatory CpG ODN could modulate the immune response towards a Th1-like response when co-administered to piglets during SPML vaccination, which suggested that the therapeutic uses envisioned for these ODNs (as vaccine adjuvants and immunoprotective agents) may be applicable to husbandry animals. 相似文献
998.
Munir K Muneer MA Tiwari A Chaudhry RM Muruganandan S 《Veterinary research communications》2007,31(7):909-929
Immunization against Angara disease virus (ADV), a serotype 4 avian adenovirus, and Newcastle disease virus (NDV), an avian
paramyxovirus serotype 1, is the mainstay of a broiler vaccination programme, while polyether ionophores usually form an essential
component of a broiler medication programme in most parts of India and Pakistan. The role of polyether ionophores in the protective
immune responses of broiler chickens vaccinated and challenged with ADV and NDV was investigated. A total of 1600 birds were
divided into eight groups of 200 birds each. First four groups were vaccinated against NDV and ADV, while the remaining four
served as unvaccinated controls. The first 3 groups of birds were administered salinomycin, monensin and cyclophosphamide
(CYP), respectively. The last group served as an untreated control. The same treatment schedule was also followed for the
next four unvaccinated groups. The post-vaccination and post-challenge serological responses to NDV and ADV, body and lymphoid
organ weight gains, post-challenge survival rate and detection of NDV and ADV in the tissues of infected birds were evaluated.
Birds administered salinomycin showed a significant stimulation of protective immune responses against both NDV and ADV as
compared to the untreated and CYP-treated birds. Monensin also enhanced the protective immune responses against both viruses
but the effect was not statistically significant. Thus, it is concluded that monensin and salinomycin augment the anti-NDV
and anti-ADV immune responses in broiler chickens, which supports their use in poultry flocks. 相似文献
999.
Wambura PN Meers J Kattenbelt JA Gould AR Spradbrow PB 《Veterinary research communications》2007,31(1):105-112
A single-tube RT-PCR technique generated a 387 bp or 300 bp cDNA amplicon covering the F0 cleavage site or the carboxyl (C)-terminus of the HN gene, respectively, of Newcastle disease virus (NDV) strain I-2. Sequence analysis was used to deduce the amino acid sequences of the cleavage site of F protein and the
C-terminus of HN protein, which were then compared with sequences for other NDV strains. The cleavage site of NDV strain I-2
had a sequence motif of 112
RKQGRLIG119, consistent with an avirulent phenotype. Nucleotide sequencing and deduction of amino acids at the C-terminus of HN revealed
that strain I-2 had a 7-amino-acid extension (VEILKDGVREARSSR. This differs from the virulent viruses that caused outbreaks of Newcastle disease in Australia in the 1930s and 1990s, which
have HN extensions of 0 and 9 amino acids, respectively. Amino acid sequence analyses of the F and HN genes of strain I-2
confirmed its avirulent nature and its Australian origin. 相似文献
1000.