轮作

North China Plain is one of the most important cereal crops production regions in China. Excessive N fertilization is a common problem in winter wheat and summer maize rotation system in this region.

华北平原是中国重要的粮食产区，氮肥过量投入是目前该地区冬小麦／夏玉米轮作体系中存在的普遍问题。

Firstly, the developing principles of the cylindrical internal helical gear are proposed through analyzing the movement and geometry requirements, which provides continuous contact between the mating gear surfaces. The tooth surface of the internal helical gear in the new gearing can be imagined as being generated by the normal section of the conjugated surface of the ball-tooth, moving along the radial projection of helix line of the tooth-root circle. Also, the proposed surface can be approximate tangent to the conjugated surface of the ball-tooth along a spacial curve.

首先，通过分析保证行星轮作螺环运动时与内斜齿轮实现连续啮合传动的运动和几何条件，提出了圆柱内斜齿轮齿面的两种形成原理：即由球齿运动包络曲面的法截面沿其齿根圆螺旋线在径向的投影进行拓展所形成的内齿面，以及与球齿运动包络曲面呈近似相切接触的等螺距齿面构成的内齿面。

To investigate the relationship between autotoxicity and continuous cropping obstacle and to find a reasonable crop rotation system for Angelica sinensis (a common traditional Chinese medicinal plant). Aqueous extracts from root, stem and leaf of A. sinensis at vegetative stage were analyzed for autotoxicity and allelopathic effect on Brassica campestris, Triticum aestivum, Avena sativa which are often grown in regions where A.

为探讨当归自毒作用与连作障碍的关系并建立合理的轮作制度，利用4个浓度当归营养期根部及茎叶部水浸液对当归及其种植区常见作物油菜、小麦和燕麦的种子和幼苗进行了生物测定。

The results showed that intercropping with faba bean changed the ammonia-oxidizer community composition in Rhizosphere of wheat.

利用DGGE技术研究了不同间作和轮作种植体系对作物根际氨氧化细菌和固氮菌群落结构的影响。

Interplanting with rounds oftreatment, In contrast can not provide a good soil microbial environment for crops.

小麦、大豆轮作和毛葱套作都可以为作物创造一个适合生长的良好的微生物环境。

Cultivation of legumes, green manures or deep-rooting plants during the rotation or as interplanting in perennial crops.

在轮作中种植豆科作物、绿肥或者是深耕作物，或在多年生作物中间作这类作物。

Wheat and soybean rotation have a better quality ofcucumber, two of soluble solids and vitamin C content is higher and the lower levels of nitrite andnitrate content, interplanting round showed a definite role in the improvement of the quality ofcucumber.

小麦及大豆轮作处理的黄瓜品质也较好，两处理的可溶性固形物及维生素C含量均较高，而硝酸盐含量及亚硝酸盐含量又较低，表明轮套作对黄瓜营养品质的改善有一定作用。

For instance, interplanting commercial crops, winter or early spring vegetables in interplanting space of wheat-maize rotation before maize seeding can increase returns significantly.

例如，在小麦玉米轮作中玉米播种前在套种带中插套经济作物、冬前和早春蔬菜可显著增加收入。

If know countrywide irrigable land has 1 million hectare many a little bit only, the loss with so such bad management is too big, the irrigable land that has 1/10 about namely is used without the rotate now.

假如知道全国的水浇地只有100万公顷多一点，那么如此治理不善的损失就太大了，即约有1/10的水浇地现在没有轮作使用。

With these databases,12 essential evaluation factors was decided,such as drainage capability,crop rotation system,parent material,soil erosion type,soil acidity,organic matter,total nitrogen,available phosphorus,available potassium,exchangeable magnes...

并在此基础上选取排涝能力、轮作制度、成土母质、土壤侵蚀类型、pH、有机质、全氮、有效磷、速效钾、交换性镁、耕层厚度、障碍层状况12个要素作为评价指标。

Objective To investigate the effects of interleukin-1 β converting enzyme gene on the biologic characteristics of ovarian cancer cells.

目的 探讨白细胞介素-1 β转换酶的表达，对卵巢癌细胞生物学特性的影响。

Campylobacter: This illness is the most commonly identified cause of diarrheal illness in the world.

弯曲：这种病是最常见的原因查明腹泻病，在世界上。