全文获取类型
收费全文 | 2831篇 |
免费 | 217篇 |
国内免费 | 280篇 |
专业分类
林业 | 219篇 |
农学 | 151篇 |
基础科学 | 112篇 |
340篇 | |
综合类 | 1406篇 |
农作物 | 178篇 |
水产渔业 | 146篇 |
畜牧兽医 | 439篇 |
园艺 | 220篇 |
植物保护 | 117篇 |
出版年
2024年 | 13篇 |
2023年 | 61篇 |
2022年 | 168篇 |
2021年 | 160篇 |
2020年 | 126篇 |
2019年 | 108篇 |
2018年 | 96篇 |
2017年 | 162篇 |
2016年 | 106篇 |
2015年 | 156篇 |
2014年 | 151篇 |
2013年 | 194篇 |
2012年 | 258篇 |
2011年 | 243篇 |
2010年 | 242篇 |
2009年 | 201篇 |
2008年 | 197篇 |
2007年 | 193篇 |
2006年 | 139篇 |
2005年 | 92篇 |
2004年 | 71篇 |
2003年 | 39篇 |
2002年 | 53篇 |
2001年 | 39篇 |
2000年 | 40篇 |
1999年 | 7篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1994年 | 2篇 |
1992年 | 2篇 |
1989年 | 1篇 |
1986年 | 1篇 |
1981年 | 1篇 |
1962年 | 1篇 |
排序方式: 共有3328条查询结果,搜索用时 15 毫秒
101.
102.
Cholesterol staining is a useful approach for the visualization, localization and quantification of cholesterol in cells or tissues, which is frequently used to investigate the mechanisms of some diseases such as arteriosclerosis, Niemann-Pick disease type C, and Alzheimer's disease. It can be accomplished through various microscopes including light microscope, fluorescent microscope, and electronic microscope. During the past decades, various types of methods for cholesterol staining with different principles have been established for different applications. It is important to choose an appropriate method that is suitable for particular experimental aims, features and conditions. At present, three kinds of methods are frequently applied: filipin fluorescent method, BCθ(a biotinylated and carlsberg protease-nicked derivative of perfringolysin O) toxin method, and cholesterol oxidase-diaminobenzidine(oxidase-DAB) method. Four kinds of methods are scarcely applied: Schultze method, perchloric acid-naphthoquinone method(PAN), digitonin method, and o-phthalaldehyde method. In this review, the principles, advantages, and disadvantages of these methods are compared with the emphasis of the application, sensitivity, and specificity. 相似文献
103.
Increasing K+ adsorption can be an effective alternative in building an available K pool in soils to optimize crop recovery and minimize losses into the environment. We hypothesized that long-term fertilization might change K+ adsorption because of changes in the chemical and mineralogical properties of a rice (Oryza sativa L.). The aims of this study were (i) to determine clay minerals in paddy soil clay size fractions using X-ray diffraction methods and a numerical diagram-decomposition method; (ii) to measure K+ adsorption isotherms before and after H2O2 oxidation of organic matter, and (iii) to investigate whether K+ adsorption is correlated with changes in soil chemical and mineral properties. The 30-yr long-term fertilization treatments caused little change in soil organic C (SOC) but a large variation in soil mineral composition. The whole-clay fraction (<5 μm) corresponded more to the fertilization treatment than the fine-clay fraction (<1 μm) in terms of percentage of illite peak area. The total percentage of vermiculite-chlorite peak area was significantly negatively correlated with the total percentage of illite peak area in the <5 μm soil particles (R=-0.946, P<0.0006). Different fertilization treatments gave significantly different results in K+ adsorption. The SOC oxidation test showed positive effects of SOC on K+ adsorption at lower K+ concentration (?120 mg L?1) and negative effects at higher K+ concentration (240 mg L?1). The K+ adsorption by soil clay minerals after SOC oxidization accounted for 60–158% of that by unoxidized soils, suggesting a more important role of soil minerals than SOC on K+ adsorption. The K+ adsorption potential was significantly correlated to the amount of poorly crystallized illite present (R=0.879, P=0.012). The availability of adsorbed K+ for plant growth needs further study. 相似文献
104.
105.
106.
108.
辽宁玉米收获机械化发展分析 总被引:2,自引:1,他引:1
玉米是辽宁第一大作物,但收获环节机械化不高.发展玉米收获机械化,对提升辽宁玉米生产能力和农业机械化水平,具有重要意义.通过对辽宁省玉米收获机械化发展现状、存在的问题以及制约因素进行分析,明确近期玉米收获机械化的发展目标及发展重点,提出促进全省玉米收获机械化发展的措施和建议. 相似文献
109.
人工湿地作为一种污水生物处理技术,因其具有独特的优势,已得到广泛的应用。针对五岳河水污染现状,结合人工湿地处理废水的特点,从场地选择、工艺类型选择等方面论述利用人工湿地法解决五岳河水污染问题的可行性。 相似文献
110.
滨海盐碱地棉花秸秆还田对土壤理化性质及棉花产量的影响 总被引:15,自引:0,他引:15
在滨海盐碱地定点设置连续3年棉花秸秆还田和未还田2个处理,研究其对0~60 cm土层土壤理化性质和棉花产量的影响。结果表明,连续3年棉花秸秆还田显著降低0~30 cm土层土壤容重和0~10 cm土层0.25 mm土壤微团聚体含量;显著提高0~10 cm土层5 mm土壤大团聚体含量。在0~20 cm土层,3年秸秆还田显著提高棉花播前和各生育阶段土壤有机质、硝态氮、铵态氮和速效钾含量,平均分别比对照提高13.45%、18.57%、22.80%和22.57%;降低土壤速效磷和含盐量,平均分别比对照降低18.29%和16.59%。在20~40 cm土层,3年秸秆还田显著提高土壤硝态氮和铵态氮含量,平均比对照提高37.20%和31.62%;显著降低土壤含盐量,平均比对照降低19.06%。在40~60 cm土层,3年秸秆还田显著提高土壤硝态氮和铵态氮含量,平均分别比对照提高38.26%和24.83%。3年棉花秸秆还田分别比未还田显著提高棉花籽棉产量11.57%、19.01%和13.24%和皮棉产量18.56%、19.78%和18.73%,但对棉花单铃重和衣分无显著影响。 相似文献