全文获取类型
收费全文 | 1976篇 |
免费 | 95篇 |
国内免费 | 125篇 |
专业分类
林业 | 158篇 |
农学 | 129篇 |
基础科学 | 97篇 |
141篇 | |
综合类 | 934篇 |
农作物 | 98篇 |
水产渔业 | 135篇 |
畜牧兽医 | 323篇 |
园艺 | 107篇 |
植物保护 | 74篇 |
出版年
2024年 | 7篇 |
2023年 | 20篇 |
2022年 | 49篇 |
2021年 | 50篇 |
2020年 | 50篇 |
2019年 | 75篇 |
2018年 | 42篇 |
2017年 | 46篇 |
2016年 | 76篇 |
2015年 | 85篇 |
2014年 | 87篇 |
2013年 | 93篇 |
2012年 | 141篇 |
2011年 | 144篇 |
2010年 | 94篇 |
2009年 | 134篇 |
2008年 | 120篇 |
2007年 | 160篇 |
2006年 | 145篇 |
2005年 | 90篇 |
2004年 | 63篇 |
2003年 | 64篇 |
2002年 | 49篇 |
2001年 | 48篇 |
2000年 | 51篇 |
1999年 | 22篇 |
1998年 | 24篇 |
1997年 | 24篇 |
1996年 | 19篇 |
1995年 | 20篇 |
1994年 | 15篇 |
1993年 | 18篇 |
1992年 | 16篇 |
1991年 | 12篇 |
1990年 | 12篇 |
1989年 | 5篇 |
1988年 | 8篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有2196条查询结果,搜索用时 0 毫秒
21.
22.
23.
24.
Du Yang Xin Mingdao Huang Shaoming 《保鲜与加工》1995,(5):50-56
A new type of three dimenstional inner microfin tube is devoloped. Under four different pressures and in the range of condensing mass velocities from 33 to 153 kg/m2 . s,and by the experimental study of the three kinds of tubes with different microfin parameters, the performances of the condensation heat transfer for R11 in the horizontal microfin tubes and obtained. The experiments show that the inner microfin tube is a hopeful and nighty effective condensing heat transfer enhancement tube. 相似文献
25.
:In
accordance with the problems, occurred in the mountainous city's construction, especially
the crises such as the destruction of ecological and humanistic environment, the loss of
traditional culture and characteristics and the disorder of urban structure, this paper
discusses the distinctive landscape characteristic of mountainous city thoroughly. 相似文献
26.
Chen Qigao Feng Ya 《保鲜与加工》1993,(1)
This paper analyses the thermal moist characteristics of the hull layer beside an air layer at lower temperature in an envelope for a cold storage and presents a new method of waterproof by air layer. With test data from engineering practice, the theory on the barrier of self moisture proof at the surface sublayer of the hull layer in an attic on a cold storage is proven. The dried zone about three phase point is confirmed. It is a new knowledge for thermophysics on thermal design of a cold storage with an optimum thermal performance. 相似文献
27.
28.
优质独本菊和多头菊规模化栽培技术试验 总被引:1,自引:0,他引:1
以独本菊和多头菊为研究对象,对其进行了育苗和栽培试验。结果表明:间歇式全光雾照扦插出的苗品质好,省时省事,B9和多效唑结合使用矮化效果好,且垄作套盆比平地套盆栽培效果好,有利于规模化生产。 相似文献
29.
30.
Sanja Radman Lara imek Sanja Babi Ana-Marija Ciko Rozelindra o-Rakovac Stela Joki Igor Jerkovi 《Marine drugs》2022,20(1)
Ericaria crinita and Ericaria amentacea from the Adriatic Sea (Croatia) were investigated with respect to the presence of less-polar compounds for the first time after fractionation by solid-phase extraction (SPE). The composition of less-polar fractions of freeze-dried E. crinita (FdEc) and E. amentacea (FdEa) were analyzed by high-performance liquid chromatography–high-resolution mass spectrometry with electrospray ionization (UHPLC-ESI-HRMS). The major identified compounds were: amides of higher aliphatic acids (palmitoleamide, linoleamide, palmitamide, oleamide and erucamide) and related compounds, carotenoid (fucoxanthin), chlorophyll derivatives (pheophytin a and b and their derivatives) and higher terpenes (loliolide, isoamijiol with its oxidation product), β-stigmasterol and (3β,6α)-14-methylergosta-8,24(28)-diene-3,6-diol). The toxic effects observed on the less-polar fractions obtained from Ericaria species on zebrafish Danio rerio embryos could be associated with the high abundance of all five detected amides. The antioxidant activity of the fractions was evaluated by means of five independent assays, including the reduction of the radical cation (ABTS), the oxygen radical absorbance capacity (ORAC), ferric-reducing antioxidant power (FRAP), the 2,2-diphenyl-1-picryl-hydrazyl (DPPH) assay and the Folin–Ciocalteu method. A higher antioxidant activity of E. amentacea in comparison to that of the E. crinita fractions was found with IC50 concentrations of 0.072 and 1.177 mg/mL, respectively. The correlation between the activity and the chemical composition revealed that the synergistic effect of different compounds impacted their antioxidant response. 相似文献