全文获取类型
| 收费全文 | 9864篇 |
| 免费 | 2181篇 |
| 国内免费 | 206篇 |
学科分类
| 农业科学 | 12251篇 |
出版年
| 2025年 | 139篇 |
| 2024年 | 223篇 |
| 2023年 | 218篇 |
| 2022年 | 269篇 |
| 2021年 | 308篇 |
| 2020年 | 314篇 |
| 2019年 | 359篇 |
| 2018年 | 186篇 |
| 2017年 | 326篇 |
| 2016年 | 393篇 |
| 2015年 | 355篇 |
| 2014年 | 523篇 |
| 2013年 | 482篇 |
| 2012年 | 818篇 |
| 2011年 | 824篇 |
| 2010年 | 634篇 |
| 2009年 | 673篇 |
| 2008年 | 619篇 |
| 2007年 | 636篇 |
| 2006年 | 535篇 |
| 2005年 | 479篇 |
| 2004年 | 398篇 |
| 2003年 | 324篇 |
| 2002年 | 239篇 |
| 2001年 | 259篇 |
| 2000年 | 249篇 |
| 1999年 | 191篇 |
| 1998年 | 179篇 |
| 1997年 | 136篇 |
| 1996年 | 162篇 |
| 1995年 | 158篇 |
| 1994年 | 126篇 |
| 1993年 | 107篇 |
| 1992年 | 108篇 |
| 1991年 | 88篇 |
| 1990年 | 71篇 |
| 1989年 | 55篇 |
| 1988年 | 34篇 |
| 1987年 | 18篇 |
| 1986年 | 8篇 |
| 1985年 | 6篇 |
| 1984年 | 6篇 |
| 1982年 | 3篇 |
| 1981年 | 2篇 |
| 1980年 | 1篇 |
| 1979年 | 3篇 |
| 1978年 | 2篇 |
| 1977年 | 2篇 |
| 1956年 | 1篇 |
| 1955年 | 1篇 |
排序方式： 共有10000条查询结果，搜索用时 0 毫秒
1.
张勇 《四川畜牧兽医学院学报》2005,3(3):112-114
随着科学技术的迅猛发展以及我国对外交往的日益频繁,外来词（借词）特别是英语词汇越来越多地渗透到我们的日常生活中.不少人对此表现出了很深的忧虑：这会不会破坏汉语文字的纯洁性？本文主要对外来词所涉及的内容、存在的依据、借用的形式以及应用等方面进行探讨,并着重指出外来词不会影响汉语的纯洁性;相反,外来词的借入会不断地丰富我们的语言宝库,因此人们应该以一种更开放的心态来吸纳外来词. 相似文献
2.
Fundamental to herbal medicine quality is the use of 'authentic' medicinal herb species. Species, however, 'represent more or less arbitrary and subjective man-made units'. Against this background, we discuss, with illustrative examples, the importance of defining species boundaries by accommodating both the fixed (shared) diagnostic and varying (within-species) traits in medicinal herb populations. We emphasize the role of taxonomy, floristic information and genomic profiling in authenticating medicinal herb species, in addition to the need to include within species phytochemical profile variations while developing herbal extract identification protocols. We outline the application of species-specific genomic and phytochemical markers, chemoprofiling and chemometrics as additional tools to develop qualifying herbal extract references. We list the diagnostic traits available subsequent to each step during the medicinal herb extract manufacturing process and delineate limits to qualification of extract references. 相似文献
3.
4.
本文首先介绍了山西省中药材生产机械化发展的现状,根据近年调研和统计数据,从中药材生产机械化各环节发展情况剖析了山西省中药材生产机械化发展中存在的问题。通过对山西省中药材生产大县、合作社、农户、机具生产厂商的调研和分析,提出了针对山西省中药材机械化发展的对策及建议,为山西省中药材生产机械化发展提供依据。 相似文献
5.
Ayne Murata Hayashi Júlia Maria Matera Tatiana Soares da Silva Ana Carolina Brand?o de Campos Fonseca Pinto Sílvia Renata Gaido Cortopassi 《Journal of veterinary science (Suw?n-si, Korea)》2007,8(1):95-98
A non-ambulatory dog with tetraparesis following a pain episode that had evolved over 2 months was submitted for medical treatment and diagnosed with intervertebral disk disease at C3-C4 and dorsal extradural compression at C1-C2 and C3-C4 using myelography and computed tomography. The dog experienced ambulation recovery after 15 days of treatment with only electroacupuncture and Chinese herbal medicine, with marked improvement occurring after only 10 treatments. Six months of follow-up demonstrated that the dog was stable and had no recurrence of symptoms. Therefore, it was concluded that the combination of electroacupuncture and Chinese herbal medicine was responsible for motor rehabilitation. 相似文献
6.
中国诗学是对以诗歌作品为核心的诗歌事实的系统的理论化的认识。一直以来,诗歌作品却处于诗学研究边缘的位置上,是隐藏的核心。在今后的研究中,诗作要放在更加突出的位置上,形成以诗歌史为母体,诗歌作品为核心,包括诗人研究、文献研究、诗体研究、写作研究、诗论研究、范畴研究等一核心、多层次的诗学体系。 相似文献
7.
Wenhua Lü 《Frontiers of Forestry in China》2008,3(1):121-126
With water-soluble phenol-formaldehyde resin as an intermediate, Chinese fir (Cunninghamia lanceolata) wood/montmorillonite nanocomposite (WMNC) was prepared through vacuum impregnation and characterized with XRD, SEM, FTIR and TG-DTA analyses. The XRD analysis indicated that the wood crystallinity of WMNC decreased, the MMT exfoliated and some nano silicate layers entered into the non-crystallized microfibrillar region of the wood cell wall. Wood structure is anisotropic and its impregnation is anisotropic. Due to the nonuniformity of the MMT organic modification, PF intercalation and wood impregnation, the MMT configuration and distribution in wood were diverse. The SEM graphs of WMNC showed that some silicate grains were blocked in the wood cell lumen, some silicate layers adhered to the inner surface of the wood cell wall, and some exfoliated MMT layers even penetrated the wood cell wall. The obtained hydroxyl of WMNC increased and its ether linking decreased. It was considered that MMT and wood interacted not only with hydroxyl bonds, but also involved some chemical linking. Compared with untreated wood and the PF-impreg, the pyrolysis process of WMNC changed; its starting decomposing temperature decreased and its pyrolysis weight loss at high temperatures greatly decreased. The WMNC indicated certain nanoeffects of the composition of the inorganic MMT nanolamellae. __________ Translated from Journal of Beijing Forestry University, 2007, 29(1): 131–135 [译自: 北京林业大学学报] 相似文献
8.
Calculation of radiation transfer within the canopy of a plantation on sloped sites is described. The canopy was assumed to consist of evenly cone-shaped crowns. Within-tree shading by object tree and between-tree shading by tree crowns around the object tree were differentiated. The two-dimensional needle area density (NAD) was introduced in the calculation of radiation transfer and interception. The model was validated with measurements of both daily photosynthetic photo flux density (PPFD) and daily photosynthetic radiation at tens of points within the crown of a 17-year-old Chinese fir (Cunninghamia lanceolata) plantation growing on a sloped site. Simulation showed that modeled data closely matched measurements. Simulation errors likely result from the uneven size of tree crowns, irregular crown shape, grouping of needles to shoots and twigs, etc. Scattering radiation amounted to below 10%, in most cases, of daily radiation, and its uncertainty was relatively small. 相似文献
9.
影响中文期刊编目数据质量的若干因素及对策 总被引：3，自引：0，他引：3
阐明了网络环境下建设高质量的中文期刊书目数据库的必要性,并针对中文期刊编目的特点,分析了影响中文期刊编目数据质量的各种主、客观因素及中文期刊编目工作中容易出现的问题,结合本馆中文期刊编目工作实际．探讨了提高中文期刊书目数据质量的若干对策。 相似文献
10.
“中国春”小麦不同缺体的RAPD分析 总被引：1，自引：0，他引：1
利用ＰＣＲ－９０Ａ型ＤＮＡ扩增仪,对７个中国春小麦缺体核ＤＮＡ进行了扩增。结果显示,中国春小麦缺体核ＤＮＡ的ＲＡＰＤ产物可分为二种类型：（１）所有供试材料均能扩增出的片段,代表了核ＤＮＡ在进化上的保守性。有一个引物检测到这类片段。（２）全部供试材料间存在的差异片段,这类片段是用来基因定位的主要依据。另外,建立中国春小麦缺体系统的ＲＡＰＤ指纹图谱对研究小麦的系统进化也将有重要意义 相似文献
