全文获取类型
收费全文 | 1753篇 |
免费 | 74篇 |
国内免费 | 103篇 |
专业分类
林业 | 35篇 |
农学 | 102篇 |
基础科学 | 18篇 |
59篇 | |
综合类 | 655篇 |
农作物 | 76篇 |
水产渔业 | 171篇 |
畜牧兽医 | 479篇 |
园艺 | 310篇 |
植物保护 | 25篇 |
出版年
2024年 | 12篇 |
2023年 | 35篇 |
2022年 | 63篇 |
2021年 | 67篇 |
2020年 | 51篇 |
2019年 | 55篇 |
2018年 | 34篇 |
2017年 | 73篇 |
2016年 | 72篇 |
2015年 | 72篇 |
2014年 | 70篇 |
2013年 | 103篇 |
2012年 | 120篇 |
2011年 | 152篇 |
2010年 | 85篇 |
2009年 | 88篇 |
2008年 | 86篇 |
2007年 | 105篇 |
2006年 | 77篇 |
2005年 | 66篇 |
2004年 | 71篇 |
2003年 | 48篇 |
2002年 | 44篇 |
2001年 | 45篇 |
2000年 | 33篇 |
1999年 | 43篇 |
1998年 | 25篇 |
1997年 | 30篇 |
1996年 | 32篇 |
1995年 | 15篇 |
1994年 | 5篇 |
1993年 | 7篇 |
1992年 | 13篇 |
1991年 | 8篇 |
1990年 | 8篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1978年 | 1篇 |
排序方式: 共有1930条查询结果,搜索用时 0 毫秒
91.
张宣葡萄产区土壤硒含量与葡萄品质关系研究 总被引:1,自引:0,他引:1
调查分析了张宣地区葡萄园产区土壤硒分布状况,并与葡萄品质进行了相关分析,结果表明:张宣葡萄产区表层土壤硒含量低于中国表层土壤硒含量,在怀涿葡萄产区总面积占67.74%的土壤属于缺硒土壤,24.73%产区土壤为少硒土壤,足硒土壤面积较少;宣化葡萄产区面积达81.82%产区土壤为足硒土壤;土壤硒含量与土壤有机质含量呈极显著正相关,与土壤pH呈极显著负相关,偏相关分析显示该产区土壤有机质与土壤硒含量的关系更密切;土壤硒含量与葡萄果实Vc有负相关关系,与果实中pH、单粒重呈正相关关系,分析表明土壤硒与酿酒葡萄品质关系密切;土层深度在土壤硒含量与葡萄品质的关系中影响不大。 相似文献
92.
葡萄冷藏中电学参数与质地特性变化规律 总被引:3,自引:1,他引:3
为了探讨采后葡萄电学参数与质地特性的变化规律,以红地球葡萄为材料,利用HIOKI 3532-50型LCR测量仪和自制平行板铜电极,在0.1~3?980 kHz频率范围内选取24个频率点,对采后冷藏果实进行了电学参数的动态测定,并研究了其与果实质地参数硬度、咀嚼性、黏着性和弹性之间的相关性,筛选出了电学参数较佳测试频率,建立了电抗X与质地参数的二元二次回归方程。结果表明,葡萄果实复阻抗Z、电感Lp、电抗X和电阻Rp随测试频率升高呈指数形式下降;在同一频率下,果实Z、Lp、X和Rp随着贮藏时间的增加呈线性下降趋势。随着果实的衰老,质地参数硬度和咀嚼性逐渐下降,黏着性绝对值和弹性呈上升趋势。在较佳测试频率0.1 kHz下,电学参数与质地参数呈现较高相关性,其中电抗X与硬度、弹性、黏着性呈现显著相关性(P<0.05),同时与咀嚼性达到较高相关性,并建立了二者之间的关联方程,为实现葡萄无损检测提供了依据。 相似文献
93.
Rongping Hu Zijing Zhang Lijin Lin Ming’an Liao Yi Tang Dong Liang 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2019,69(4):304-310
In this experiment, four cadmium (Cd) hyperaccumulator species (Crassocephalum crepidioides, Galinsoga parviflora, Sigesbeckia orientalis, and Solanum nigrum) were intercropped with grape (Vitis vinifera) cuttings together in Cd-containated soil to study the effects of intercropping with the Cd-hyperaccumulator plants on growth and Cd accumulation of grape seedlings. Compared with the monoculture, intercropping with S. nigrum increased the biomass of grape seedlings, but intercropping with the other three hyperaccumulator species decreased the grape seedling biomass. Intercropping with S. nigrum increased chlorophyll a and total chlorophyll contents in leaves of grape seedlings compared with the monoculture, whereas intercropping with the other three hyperaccumulator species showed either a decrease or no effect. Intercropping with hyperaccumulator plants had no significant effects on chlorophyll b and carotenoid contents in leaves of grape seedlings compared with the monoculture. Compared with the monoculture, intercropping with C. crepidioides, G. parviflora, S. nigrum and S. orientalis significantly decreased Cd contents in shoots of grape seedlings by 78.7%, 12.7%, 29.8% and 26.5%, respectively. Therefore, intercropping with hyperaccumulator plants can decrease Cd accumulation in grape, and intercropping with S. nigrum can also promote grape seedling growth. 相似文献
94.
95.
96.
《Communications in Soil Science and Plant Analysis》2012,43(8):593-605
Abstract The leaf opposite the first fruit cluster was used for the investigation of grape nutrition at bloomtime and ripening. The data show that blade analysis and petiole analysis are both suitable for the assessment of the nutrient status in the case of P, K, Mg and Ca. However, the data obtained for nitrogen differ markedly, depending on the organ considered. For phosphorus and potassium, the differences in nutrient content between vineyards as well as the seasonal variations are better reflected by petiole analysis. This effect, which should be favourable to the diagnosis, is paralleled by a wider scattering of the nutrient levels; as a result, the differences observed in the petiole are not statistically more significant than those in the blade. Under relatively homogeneous conditions (same variety, same climate), the differences induced by variable parameters (soil type, sampling times, years) appear to be fluctuating, so that nutrient reference levels cannot be recommended, whether for the blade or the petiole. Both sampling modes (blade or petiole) are complementary to each other and could therefore be used advantageously for a better control of grape nutrition and fertilization. 相似文献
97.
AIM: To investigate the potential mechanisms of renoprotective effect of grape seed proanthocyanidin (GSP) on diabetic nephropathy.METHODS: Male Wistar rats were injected with 1% streptozotocin (STZ) intravenously to induce diabetes mellitus (DM). The diabetic rats were randomly divided into 2 groups: diabetes group (DM group) and GSP treatment group (GSP group, GSP 250 mg·kg-1·d-1). The normal Wistar rats served as control (C group). Body weight (BW), systolic pressure, kidney weight/body weight (KW/BW), fasting plasma glucose (FPG), blood urea nitrogen (BUN), serum creatinine (SCr), glycosylated hemoglobin (HbA1c) and 24 h urine protein were determined 24 weeks after STZ intervention. The pathological changes of the renal tissues were observed. The protein levels of glutathione S-transferase mu (GSTM) and nuclear factor-erythroid 2-related factor 2 (Nrf2) in the renal tissues were determined by Western blotting and immunohistochemistry. RESULTS: Compared with C group, BW in diabetic rats decreased (P<0.01). The levels of systolic pressure, FPG, HbA1c, KW/BW, 24 h urine protein, BUN and SCr in DM group were higher than those in C group (P<0.01). After treated with GSP, the levels of systolic pressure, KW/BW, 24 h urine protein, BUN and SCr in DM rats were lower than those in DM rats without treatment (P<0.01 or P<0.05). The pathological changes were ameliorated in GSP group. The expression of GSTM and Nrf2 was up-regulated in the kidneys of diabetic rats and down-regulated to the normal levels after GSP treatment. CONCLUSION: The renoprotective effect of GSP is associated with the down-regulation of GSTM through modulating the expression of Nrf2. 相似文献
98.
葡萄霜霉病预测模型及预警技术研究进展 总被引:3,自引:4,他引:3
霜霉病是危害葡萄最严重的病害之一,目前采用的主要防治手段是喷施化学农药,但其用量过多也带来许多严重问题。若要减轻农药污染,就必须对病害进行精确的预测预报,以便确定最合理的农药使用时机和使用量。在此,从病害流行系统的监测、因子选择、结构及应用等方面综述了利用农业气象模型预测葡萄霜霉病的研究应用进展,并对其存在的问题及发展前景作了讨论。 相似文献
99.
本研究旨在观察阿勒泰大尾羊尾脂油脂对损伤皮肤是否具有修复作用,并与牛油脂、市售商品做比较。研究选择40 只体重在31 ± 1 g 之间的昆明小鼠,雌雄各半,通过构建小鼠皮肤损伤模型,将小鼠分为4 组(羊尾油组、牛油组、市售商品组和空白组)进行试验观察。小鼠皮肤伤口愈合良好,雌鼠的创面愈合能力强于雄鼠,雌鼠伤口愈合速度:羊尾油组>牛油组>市售商品组>空白对照组。雄鼠伤口愈合速度:羊尾油组>市售商品组>牛油组>空白对照组。皮肤组织病理学结果显示,涂抹羊尾脂、牛油脂、市售商品与空白对照处皮肤相比,创伤修复组织中脂肪细胞、胶原纤维以及其他细胞的数量、排列分布均有差异。羊尾油和牛油均有修复皮肤创伤的作用,且羊尾油修复作用更强,羊尾油可通过促进胶原纤维的生成加速皮肤修复。 相似文献
100.
原花青素是一类广泛存在于植物界的多酚化合物的总称,其中以葡萄籽的含量最为丰富。研究表明,葡萄籽原花青素(GSP)有多种生物学活性。笔者综述了GSP的清除自由基、抗氧化、抗肿瘤、降血脂等生物学功能研究及其在畜禽生产上的应用研究进展,提出了将GSP作为新型饲料添加剂以提高动物的免疫力、肉品品质和抗应激作用,为GSP进一步开发和利用提供参考。 相似文献