全文获取类型
收费全文 | 27133篇 |
免费 | 1726篇 |
国内免费 | 2222篇 |
专业分类
林业 | 2395篇 |
农学 | 1211篇 |
基础科学 | 1186篇 |
2440篇 | |
综合类 | 12876篇 |
农作物 | 1833篇 |
水产渔业 | 1595篇 |
畜牧兽医 | 4226篇 |
园艺 | 2221篇 |
植物保护 | 1098篇 |
出版年
2024年 | 158篇 |
2023年 | 479篇 |
2022年 | 1168篇 |
2021年 | 1188篇 |
2020年 | 1139篇 |
2019年 | 1110篇 |
2018年 | 815篇 |
2017年 | 1280篇 |
2016年 | 832篇 |
2015年 | 1338篇 |
2014年 | 1362篇 |
2013年 | 1751篇 |
2012年 | 2384篇 |
2011年 | 2354篇 |
2010年 | 2192篇 |
2009年 | 2066篇 |
2008年 | 1957篇 |
2007年 | 1839篇 |
2006年 | 1549篇 |
2005年 | 1178篇 |
2004年 | 751篇 |
2003年 | 497篇 |
2002年 | 519篇 |
2001年 | 454篇 |
2000年 | 440篇 |
1999年 | 177篇 |
1998年 | 24篇 |
1997年 | 10篇 |
1996年 | 7篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 12篇 |
1992年 | 5篇 |
1991年 | 1篇 |
1989年 | 2篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1981年 | 6篇 |
1966年 | 1篇 |
1965年 | 2篇 |
1962年 | 8篇 |
1959年 | 1篇 |
1956年 | 9篇 |
1955年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
142.
从两个方面优化杉木[Cunninghamia lanceolata(Lamb.)Hook.]组培苗生根质量,一是在增殖阶段对其进行高浓度和低浓度激素培养基交替处理以优化组培芽苗的质量,从而达到优化杉木组培苗生根质量;二是在生根阶段改变光源,以优化杉木组培苗生根质量。结果表明,高浓度激素和低浓度激素交替处理后的杉木增殖芽苗,具有增殖率高、生长快、节间距适中、木质化程度较高等表观性状,且这些性状随着继代次数的增加表现比较稳定,增殖芽接种到生根培养基后,生根率最高达到86.5%,生根数量最高达到2.7条。LED复合光源红蓝光配比为2∶1时生根率最高,达到86.7%;在红蓝光配比为4∶1时生根数量最高,达到2.8条。 相似文献
143.
LI Yan-jun SONG Shao-rui GUO Ya-fen LAN Gan-qiu CHEN Bao-jian YAN Xue-yu WU Yan-jun JIANG Qin-yang 《中国畜牧兽医》2015,42(7):1770-1776
The atherosclerosis (AS) model was prepared in Guangxi Bama mini-pig,and the atherosclerosis index (AI) was preliminarily identified in occurrence of AS to provide the basis for the preparation of related models.20 Guangxi Bama mini-pigs were randomly divided into control group and experimental group which were fed with high fat and cholesterol diet to prepare the AS model.Blood biochemical indexes were detected in the process of model preparation and the correlation between AI and the results of vascular slices was analyzed to initially draw up AI of AS.The results of vascular slices showed that the incidence rates of AS of Guangxi Bama mini-pigs in experimental group and control group were 20% and 0,respectively.The association analysis between the results of vascular slices and AI in the pathogenic Guangxi Bama mini-pigs preliminarily suggested that AI was above 3.8 and lasted for more than 3 months during the attack. 相似文献
144.
In this article, through the combination of nucleic acid probes and immune chromatography, a simple, sensitive and specific detection system——nucleic acid lateral flow immunoassay (NALFIA) for amplifing foot-and-mouth disease virus (FMDV) 3D RT-PCR products was established.An ultrasensitive nucleic acid biosensor (NAB) based on streptavidin-labeled gold nanoparticles dual labels and lateral flow strip biosensor (LFSB) were used in this system.The biotinylated goat anti-rabbit IgG was marked to the NC membrane as the alleged strip and the anti-digoxin antibody was labeled to the NC membrane to capture the digoxin probe.After assemblying gold-labeled strip and detecting RT-PCR products, the detection limit of NALFIA was 0.3×10-3 to 3×10-3 μg/μL.The NALFIA was compared with agar gel electrophoresis analysis, the results showed that the sensitivity of NALFIA was higher than agar gel electrophoresis.There was an excellent agreement between the two methods.NALFIA was a method with high sensitive, low cost and short time.In conclusion, this method provided a good alternative to detect FMDV. 相似文献
145.
WU Ting-ting LI Jin-yu WU Cun-xiang SUN Shi MAO Ting-ting JIANG Bing-jun HOU Wen-sheng HAN Tian-fu 《中国农业科学(英文版)》2015,(4):622-632
Soybean(Glycine max(L.) Merr.) is a typical short-day and warm season plant, and the interval between emergence and flowering has long been known to be regulated by environmental factors, primarily photoperiod and temperature. While the effects of photoperiod and temperature on soybean flowering have been extensively studied, a dissection of the component photo-thermal effects has not been documented for Chinese germplasm. Our objective of the current study was to evaluate the independent- and interactive-photo-thermal responses of 71 cultivars from 6 ecotypes spanning the soybean production regions in China. These cultivars were subjected in pot experiments to different temperature regimes by planting in spring(low temperature(LT)) and summer(high temperature(HT)), and integrating with short day(SD, 12 h), natural day(ND, variable day-length), and long day(LD, 16 h) treatments over two years. The duration of the vegetative phase from emergence to first bloom(R1) was recorded, and the photo-thermal response was calculated. The outcome of this characterization led to the following conclusions:(1) There were significant differences in photo-thermal response among the different ecotypes. High-latitude ecotypes were less sensitive to the independent- and interactive-photo-thermal effects than low-latitude ecotypes; and(2) there was an interaction between photoperiod and temperature, with the effect of photoperiod on thermal sensitivity being greater under the LD than the SD condition, and with the effect of temperature on photoperiodic sensitivity being greater under the LT than the HT condition. The strengths and limitations of this study are discussed in terms of implications for current knowledge and future research directions. The study provides better understanding of photo-thermal effects on flowering in soybean genotypes from different ecotypes throughout China and of the implications for their adaptation more broadly. 相似文献
146.
AIM: In order to observe the myocardial differentiation capacity of the dedifferentiated fat (DFAT) cells treated with vitamin C in vitro. METHODS: DFAT cells were dedifferentiated from the mature rat adipocytes with ceiling adherent culture. The DFAT cells of passage 3 were used in the study. Vitamin C and/or neonatal rat heart tissue lysate were added into the culture medium to induce myocardial differentiation for 3 weeks. The cell morphology was observed under microscope. The myocardial-specific markers, such as cTnT, GATA-4 and NKx2.5, were examined by the methods of immunofluorescence, PCR and Western blot. RESULTS: Mature rat adipocytes dedifferentiated into fibroblast-like DFAT cells after ceiling adherent culture. The DFAT cells spontaneously differentiated into cardiomyocyte-like cells under normal culture condition with a low incidence. After treated with neonatal rat heart cell lysate, the DFAT cells became cardiomyocyte-like cells that had bigger size, longer shape and myotubule-structure. The expression of cTnT, GATA-4 and NKx2.5 was remarkably increased at both mRNA and protein levels as compared with the normal cultured DFAT cells. The expression of cTnT, GATA-4 and NKx2.5 was further increased in DFAT cells after treating with vitamin C. No spontaneous beating cell was observed. CONCLUSION: Vitamin C enhances the differentiation of DFAT cells into cardiomyocyte-like cells. 相似文献
147.
随着十多年的超速发展,我国奶牛业已由单一品种的散养方式逐步转变为高产品种的规模化、集约化养殖方式。然而,我国奶牛整体遗传素质不高,多为进口高产奶牛与地方奶牛的低代次改良品种,以致原奶质量参差不齐,严重制约了我国奶业的健康发展。因此,大规模引进高品质的奶牛品种,已成为我国优化奶牛基因、推动畜牧业产业化发展的重要抓手,但同时也为检疫工作带来了挑战。本文通过分析2018年我国进口奶牛数量、来源国、疫病检出、进境口岸及隔离检疫场分布等数据,结合各来源国的疫病防控特点,有针对性地提出检疫要点,为我国全面提升进口奶牛的检疫水平、切实做好奶牛群体遗传改良计划、加快推进畜牧业转型升级提供参考。 相似文献
148.
为了研究性别对查吾拉地区牦牛的产肉性能及肉营养成分的影响,随机选取8岁健康的查吾拉牦牛10头,公母各半,对不同组别间牦牛进行屠宰试验比较肉营养品质的差异。结果表明,母牦牛屠宰率、净肉率、胴体率、骨肉比均高于公牦牛,但无统计学差异。肉营养成分分析结果显示,母牦牛肉中维生素A、E、B12、半胱氨酸、组氨酸、精氨酸、钙、硒、脂肪酸含量高于公牦牛(P<0.05)。研究结果表明,查吾拉牦牛富含较高的营养成分,可为人类提供优质健康的动物蛋白,具备作为优质牦牛肉源生产的潜力。相比较,母牦牛肉优于公牦牛。 相似文献
149.
不同的样本特性和提取方法对获得微生物总DNA的质量有重要影响。文章基于高含固率木质纤维素厌氧发酵物腐殖酸、酚类物质含量高、质地均一性差、微生物浓度低的特点,研究了4种方法提取不同高含固率粪秸厌氧发酵物中微生物总DNA的效果。结果表明,常规的十二烷基磺酸钠法(sodium dodecyl sulfate,SDS)、十二烷基磺酸钠和溴化十六烷基三甲铵结合法(sodium dodecyl sulfate and cetyltrimethyl ammonium bromide,SDS-CTAB)和商业的粪便试剂盒法提取的DNA质量均较差,SDS法和试剂盒法未能获得聚合酶链式反应(polymerase chain reaction,PCR)扩增目的条带,SDS-CTAB法得到的条带较模糊;改进SDS-CTAB法获得的DNA杂质少、纯度高,具有较好的稳定性,A260/A280和A260/A230值分别为1.74~1.86和1.65~1.86,每克样品的DNA浓度在50 ng·μL^-1以上,电泳条带单一齐整、清晰明亮,PCR扩增的目的条带清晰度高,适宜后续分子生物学技术的分析。林格氏液洗脱、聚乙烯吡咯烷酮-40(Polyvinyl Pyrrolidone-40,PVP-40)洗涤液除杂以及裂解液和多种酶联合破壁是改进SDS-CTAB法获得该类专一性样本高质量微生物总DNA的关键步骤。 相似文献