全文获取类型
收费全文 | 11158篇 |
免费 | 593篇 |
国内免费 | 1323篇 |
专业分类
林业 | 1327篇 |
农学 | 1937篇 |
基础科学 | 1085篇 |
1918篇 | |
综合类 | 3181篇 |
农作物 | 520篇 |
水产渔业 | 360篇 |
畜牧兽医 | 1469篇 |
园艺 | 394篇 |
植物保护 | 883篇 |
出版年
2024年 | 31篇 |
2023年 | 131篇 |
2022年 | 281篇 |
2021年 | 472篇 |
2020年 | 377篇 |
2019年 | 378篇 |
2018年 | 289篇 |
2017年 | 395篇 |
2016年 | 378篇 |
2015年 | 508篇 |
2014年 | 502篇 |
2013年 | 582篇 |
2012年 | 743篇 |
2011年 | 772篇 |
2010年 | 671篇 |
2009年 | 668篇 |
2008年 | 625篇 |
2007年 | 660篇 |
2006年 | 614篇 |
2005年 | 620篇 |
2004年 | 272篇 |
2003年 | 246篇 |
2002年 | 193篇 |
2001年 | 195篇 |
2000年 | 273篇 |
1999年 | 298篇 |
1998年 | 259篇 |
1997年 | 260篇 |
1996年 | 212篇 |
1995年 | 218篇 |
1994年 | 201篇 |
1993年 | 151篇 |
1992年 | 137篇 |
1991年 | 103篇 |
1990年 | 94篇 |
1989年 | 80篇 |
1988年 | 68篇 |
1987年 | 40篇 |
1986年 | 24篇 |
1985年 | 9篇 |
1984年 | 8篇 |
1983年 | 8篇 |
1982年 | 8篇 |
1981年 | 13篇 |
1980年 | 5篇 |
1979年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
991.
The main content dealt with in this paper is to present a new apparatus which can be used to evaluate stiffness handle of textile materials. The comprehensive handle evaluation system for fabrics and yarns (CHES-FY) is the kind of apparatus developed into measuring stiffness handle of fabric based on the pulling-out force and displacement curves. The present work aims to feature indexes from the above curves to explain stiffness handle of fabric. These indexes, including slope and area as well as peak value, were featured from the pulling-out force and displacement curves to discriminate stiffness handle of fabrics by K-means cluster method. In order to verify the effectiveness, the subjective judgments were also made and compared with the objective K-means cluster method. The experimental results show that a good correlation exists between the subjective judgment method and objective cluster method. It indicates that the indexes featured from the pullingout force and displacement curves can be utilized to characterize stiffness handle of fabrics, and the CHES-FY system is feasible in measuring stiffness handle of fabrics. 相似文献
992.
993.
994.
P. S. Gaunt C. Langston C. Wrzesinski D. Gao P. Adams L. Crouch D. Sweeney R. Endris 《Journal of veterinary pharmacology and therapeutics》2013,36(5):502-506
Plasma disposition of florfenicol in channel catfish was investigated after an oral multidose (10 mg/kg for 10 days) administration in freshwater at water temperatures ranging from 24.7 to 25.9 °C. Florfenicol concentrations in plasma were analyzed by means of liquid chromatography with MS/MS detection. After the administration of florfenicol, the mean terminal half‐life (t1/2), maximum concentration at steady‐state (Css(max)), time of Css(max) (Tmax), minimal concentration at steady‐state (Css(min)), and Vc/F were 9.0 h, 9.72 μg/mL, 8 h, 2.53 μg/mL, and 0.653 L/kg, respectively. These results suggest that florfenicol administered orally at 10 mg/kg body weight for 10 days could be expected to control catfish bacterial pathogens inhibited in vitro by a minimal inhibitory concentration value of <2.5 μg/mL. 相似文献
995.
Yan Li Ying Jia Kai Wen Hua Liu Mingchun Gao Bo Ma Wenlong Zhang Junwei Wang 《Veterinary immunology and immunopathology》2013,151(3-4):331-336
Bovine viral diarrhea virus (BVDV) is a member of the genus Pestivirus within the family Flaviviridae. NS3 is one of the immunodominance regions of the BVDV viral proteins. To identify the potential B-cell linear antigenic epitopes within BVDV NS3 region, serial overlapping truncations covering the whole region were expressed and purified, and screened by multistep of Western-blot. We found (1VCKKITEHERCHVNI15), (20AFFGVMPRGTTPRAPVR36), (46RRGLETGWAYTHQGGI61), (281EGDMATGITYASYGYFC297), (426YSGEDPANLRVVTSQSPYVVVATNAIESGV455) and (481FIVTGLKRMAVTVGEQA497) can be recognized by the BVDV infected bovine serum. These proteins have been confirmed by indirect enzyme-linked immunosorbent assay (I-ELISA). The results of this study might open new perspectives on the structure and antibody–antigen reaction of the non-structural proteins and may aid in the clinical application as well. 相似文献
996.
欧盟是我国蜂蜜出口重要的市场,2011年下半年以来,欧盟要求检测蜂蜜中的转基因成分,我国转基因作物种植的品种和数量不断增加,转基因成分在蜂蜜中存在的风险性也不断加大。欧盟官方推荐在食品中如果使用经批准的转基因花粉含量占总花粉含量超过0.9%的蜂蜜时应当予以标识,在0.9%限量界定方面,目前倾向的鉴定方法是用PCR方法与显微镜检验相结合的方法。欧盟官方认可的QSI实验室和intertek实验室目前检测蜂蜜中转基因花粉成分时,选择的三个筛选基因为P-35S、T-NOS和FMV基因。 相似文献
997.
H. F. Wang K. Gao C. Wang W. M. Zhang J. X. Liu 《Acta Agriculturae Scandinavica, Section A - Animal Sciences》2013,63(3):143-150
AbstractThe experiment was designed to evaluate effects of feeding bamboo vinegar (BV) and acidifier to substitute antibiotic on the growth performance and intestinal bacterial communities of weaned piglets. Three hundred and sixty weaned piglets (body weight (BW) = 10 ± 2 kg) were allocated into three treatments for 25 days of experiment feeding, with three replicates (pen) per treatment. A basal diet was added with antibiotics (Control), 0.4% BV and 0.25% acidifier I (BVAI), or 0.4% BV and 0.25% acidifier II (BVAII), respectively. No significant differences were observed in feed intake, final weight, average daily gain and feed to gain ratio (P > 0.05) among different treatments. The species richness and bacterial community diversities in feces were higher for the pigs in treatment BVAI and BVAII than those of pigs in the Control (36.5 and 1.55, respectively), with a significant difference between BVAII and the Control (P < 0.05). The bacterial communities of pigs in BVAI and BVAII clustered together, forming a cluster we designated as Cluster C and separated from another cluster in pigs fed antibiotic designated as Cluster A in the Control treatment. The results indicate that the 0.4% BV and 0.25% acidifier can replace antibiotics in the diets for piglets without negative effects on production and allow for greater diversity of the intestinal bacterial community compared to antibiotics. 相似文献
998.
为快速检测规模化猪场猪瘟病毒(Classical swine fever virus,CSFV),本研究参考GenBank中登录的CSFV序列设计引物,利用实时荧光PCR技术,构建重组质粒作为阳性标准品,建立特异、敏感、重复性好的CSFV快速定量检测方法.同时建立标准曲线,用于对猪瘟病毒的定量分析.本方法对规模化猪场的100份抗凝血和50份公猪精液样品进行检测,常规PCR检出27份占18%,荧光定量PCR检出123份占82%.表明荧光定量RT-PCR方法在检测猪瘟样品中具有潜在的应用价值,同时可检测猪群中猪瘟病毒持续性感染的状态存在. 相似文献
999.
@@进入新世纪以来,伴随SARS、禽流感和猪链球菌病等疫情在全球范围内的传播,对世界各国人民的身体健康构成极大威胁。因此,国家逐步加大对动物疫病的防控,相继颁布了《中华人民共和国动物防疫法》《动物检疫管理办法》等法律法规,使我国动物防疫和检疫工作走上了有法可依、有章可循的规范化、法制化轨道。屠宰检疫是动物检疫工作的重要组成部分,是保证人民群众食肉安全的重要手段。猪肉及猪产品是广大群众餐桌上不可或缺的食品,国家为保证生猪产品质量安全,保障人民身体健康对生猪屠宰实行定点屠宰、集中检疫,从而使重大疫病的发生和流行得到有效控制。 相似文献
1000.
为了解和掌握禽白血病在贵阳地区发生和流行的基本情况,采用禽白血病A、B亚群抗体(ALV-A或B)和J亚群抗体(ALV-J)检测试剂盒,对贵阳市13个养鸡场中的15个肉鸡和商品蛋鸡共481份血清进行禽白血病抗体间接ELISA检测,结果 ALV抗体阳性率达到11.43%(55/481),其中9个鸡群172份血清样本A、B亚群抗体阳性率达到18.60%(32/172),13个鸡群309份血清J亚群抗体阳性率达到7.44%(23/309),结果表明该地区存在禽白血病病毒的感染。 相似文献