全文获取类型
收费全文 | 412篇 |
免费 | 29篇 |
国内免费 | 32篇 |
专业分类
林业 | 15篇 |
农学 | 11篇 |
基础科学 | 12篇 |
38篇 | |
综合类 | 121篇 |
农作物 | 18篇 |
水产渔业 | 14篇 |
畜牧兽医 | 205篇 |
园艺 | 21篇 |
植物保护 | 18篇 |
出版年
2024年 | 5篇 |
2023年 | 13篇 |
2022年 | 12篇 |
2021年 | 10篇 |
2020年 | 17篇 |
2019年 | 18篇 |
2018年 | 15篇 |
2017年 | 28篇 |
2016年 | 10篇 |
2015年 | 21篇 |
2014年 | 30篇 |
2013年 | 26篇 |
2012年 | 40篇 |
2011年 | 22篇 |
2010年 | 36篇 |
2009年 | 24篇 |
2008年 | 23篇 |
2007年 | 12篇 |
2006年 | 13篇 |
2005年 | 12篇 |
2004年 | 10篇 |
2003年 | 4篇 |
2002年 | 6篇 |
2001年 | 11篇 |
2000年 | 7篇 |
1999年 | 3篇 |
1998年 | 8篇 |
1997年 | 6篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有473条查询结果,搜索用时 15 毫秒
91.
为了丰富兰州地区湿地水生植物资源,从河北白洋淀地区引入水生植物14个品种,对其生态适应性和越冬性进行了观察与研究,并根据引种植物在兰州地区的生长情况,制定了评价标准,最终筛选出了‘花叶水葱’‘花叶芦苇’‘水生鸢尾’‘菖蒲’‘慈姑’‘泽泻’‘红蓼’‘雨久花’‘水生美人蕉’(红花)和‘水生美人蕉’(黄花)10个适应力强和观赏价值高的水生植物品种. 相似文献
92.
Mitter Eduardo Kovalski dos Santos Graziely Cristina de Almeida Érica Janaína Rodrigues Morão Luana Galvão Rodrigues Heide Dayane Prates Corso Carlos Renato 《Water, air, and soil pollution》2012,223(2):765-770
With the development of the textile industry, there has been a demand for dye removal from contaminated effluents. In recent
years, attention has been directed toward various natural solid materials that are capable of removing pollutants from contaminated
water at low cost. One such material is sugarcane bagasse. The aim of the present study was to evaluate adsorption of the
dye Acid Violet Alizarin N with different concentrations of sugarcane bagasse and granulometry in agitated systems at different
pH. The most promising data (achieved with pH 2.5) was analyzed with both Freundlich and Langmuir isotherms equations. The
model that better fits dye adsorption interaction into sugarcane bagasse is Freundlich equation, and thus the multilayer model.
Moreover, a smaller bagasse granulometry led to greater dye adsorption. The best treatment was achieved with a granulometry
value lower than 0.21 mm at pH 2.50, in which the total removal was estimated at a concentration of 16.25 mg mL−1. Hence, sugarcane bagasse proves to be very attractive for dye removal from textile effluents. 相似文献
93.
研究目的是检测荷包猪FUT 1和Mx1基因位点多态性及其与免疫指标的相关关系。采用PCR-RFLP技术分析基因多态性,采用ELISA方法检测免疫指标白介素-4(IL-4)、分泌型免疫球蛋白A(sIgA)、α-干扰素(IFN-α)的表达量。结果表明,荷包猪FUT 1基因和Mx1基因Hin6I点酶切位点上显示多态性,优势基因型分别为GG和AA型,在Mx1基因其他两位点处未发现多态性;荷包猪免疫指标IL-4、sIgA、IFN-α的表达量明显高于大白猪(P<0.05),但抗性基因型与免疫指标间的相关性表现不明显。 相似文献
94.
丹江口库区坡耕地不同轮作模式作物生产力及农田养分流失比较 总被引:6,自引:0,他引:6
在丹江口库区习惯施肥条件下,比较坡耕地不同轮作系统的作物生产力及农田水土和养分流失的差异。结果表明,在5种轮作模式中,作物生产力水平以"小麦-玉米"轮作最高,生产效益以"油菜-玉米"轮作最高;农田产流量、土壤侵蚀量和磷钾养分流失量均以"小麦-玉米"轮作最小,"小麦-芝麻"轮作最大;而氮流失量以"油菜-玉米"轮作最小,以"小麦-芝麻"轮作最大。因此,"小麦-玉米"轮作为丹江口库区坡耕地适宜的环保型作物复种模式。 相似文献
95.
96.
Comparative Analysis of Azo Dye Biodegradation by Aspergillus oryzae and Phanerochaete chrysosporium
The paper reports ultraviolet matrix-assisted laser desorption/ionization mass spectroscopy (UVMALDI-MS) protocol for determination of complex heterogeneous emulsion or suspension formulations. The active agents and surfactants are morpholine fungicide fenpropimorph (1), amorolfine (2), tridemorph (mixture of 2,6-dimethyl-4-alkylmorpholins 3–6), 2,6-dimethyl-4-[2-methyl-3-(6-methyl-decahydro-naphthalen-2-yl)-propyl]-morpholine (7), dodemorph (8), main metabolite of 1 fenpropimorph acid (9), sodium dodecyl sulfate (10), and stearate (11). The full method and techniques validation as well as method performance parameters are discussed in terms of their maximal representativeness toward real environmental and foodstuff assay problems. These are additionally complicated by heterogeneous laterally, vertically, and time distribution of pesticide contaminants and their major metabolites in environmental samples. The real environmental heterogeneous distribution is elucidated, studying sterilized soil fractions with particle size 2.0 μm, clay content 11.5 %, silt 23.0 %, sand 8.1 %, and pH?∈ 6.0–8.1. A statistical sampling cluster approach is used. The method performance parameters are concentration LODs of 0.026 mg kg?1 (res. LOQs 0.08666 mg kg?1). Concentration linear dynamic ranges are ∈?0.025–7.3 mg kg?1 (r 2?=?0.99822 and 0.99421) and ∈?2.3–7.4 mg kg?1 (level of confidence of 99.331?%) for complex spiked heterogeneous soil samples. The data illustrates the great capability of method and its promising application for environmental contamination monitoring and controlling programs for assessment. 相似文献
97.
随着高等教育事业的发展,国家对高校设备经费投入也逐年增加,但目前的投入远不能满足高等教育事业快速发展的需求。同时,普遍存在的一个情况是,各个高校的设备使用率较低,资源闲置。在有限的资金投入下,如何提高现有设备使用效益,成为最有效的解决这一瓶颈的关键。文章根据云南大学教学科研设备使用情况,结合信息学院目前实验室现有仪器设备及教学任务,探讨了一些高校仪器设备管理的经验和方法。尤其探讨了学校根据实际情况,自主研发了资产管理系统,进一步规范了资产管理工作,提高了设备使用效益,特别是针对大型仪器设备,建立共享平台,实行预约制度,充分体现了大型设备的资源优势。 相似文献
98.
99.
基于对松嫩草原优势物种羊草(Leymus chi-nensis)及其主要伴生种的空间分布格局、植物种间关系对割草的响应,以及羊草、芦苇(Phragmites communis)对营养和胁迫的适应性与种间关系的研究,探讨了植物竞争和共存的潜在机制。 相似文献
100.
AIM To investigate the effect of exosomes secreted by mouse melanoma cells on the expression of Ras-related C3 botulinum toxin substrate 1 (Rac1) protein in fibroblasts. METHODS Ultracentrifugation was adopted to separete exosomes secreted by mouse melanoma B16-F10 cells. The morphological structure of exosomes was observed by negative-staining electron microscopy. The size distribution of exosomes was determined by nanoparticle tracking analysis (NTA). The exosomal markers, tumor susceptibility gene 101 (Tsg101) and tyrosinase-related protein 2 (Tyrp2), were identified by Western blot. Laser confocal microscopy was used to observe the process that mouse embryonic fibroblasts (MEF) took in exosomes during co-culture. Immunocytochemical staining and Western blot were used to detect the expression of Rac1 protein in MEF. RESULTS B16-F10 cell exosomes showed a typical tea tray-like structure, with a size range of 141~255 nm, and expressed protein markers Tsg101 and Tyrp2. The results of laser confocal microscopy showed that compared with co-culture at 0 h, a small number of exosomes appeared in the MEF at 12 h, and a large number of exosomes accumulated in the MEF after co-cultured for 24 and 36 h. Western blot analysis showed that compared with co-culture at 0 h, the expression of Rac1 protein in the MEF was significantly increased at 24 h and 36 h of co-culture (P <0.01). The results of immunocytochemical staining showed that compared with co-culture at 0 h, the positive expression level of Rac1 in the MEF cells was significantly increased at 12 h, 24 h and 36 h of co-culture (P <0.05 or P <0.01). CONCLUSION Intake of exosomes secreted by mouse melanoma cells promotes the expression of Rac1 protein in fibroblasts. 相似文献