首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   197篇
  免费   7篇
林业   16篇
农学   5篇
  27篇
综合类   15篇
农作物   2篇
水产渔业   22篇
畜牧兽医   101篇
园艺   4篇
植物保护   12篇
  2023年   1篇
  2022年   3篇
  2021年   2篇
  2019年   3篇
  2018年   3篇
  2017年   2篇
  2016年   5篇
  2015年   6篇
  2014年   6篇
  2013年   14篇
  2012年   7篇
  2011年   15篇
  2010年   2篇
  2009年   2篇
  2008年   10篇
  2007年   7篇
  2006年   9篇
  2005年   8篇
  2004年   7篇
  2003年   8篇
  2002年   7篇
  2001年   11篇
  2000年   7篇
  1999年   7篇
  1998年   2篇
  1997年   2篇
  1996年   2篇
  1995年   1篇
  1994年   2篇
  1992年   2篇
  1991年   3篇
  1990年   2篇
  1989年   5篇
  1988年   4篇
  1987年   7篇
  1986年   4篇
  1983年   1篇
  1982年   1篇
  1981年   1篇
  1975年   2篇
  1974年   3篇
  1973年   3篇
  1972年   1篇
  1970年   1篇
  1969年   1篇
  1968年   1篇
  1966年   1篇
排序方式: 共有204条查询结果,搜索用时 46 毫秒
41.
Application of nitrogen (N) fertilizer at the flowering stage changed the contents of storage compounds in seeds of Soybean (Glycine max L. cvs Enrei and Tamahomare). The effects of the N application on the maturation of soybean seeds were examined by comparing changes in the contents of amino acids, sugars, water, protein, and oil in seeds from N‐dressed plants (NDS) with those from undressed plants (UDS) during maturation. The application resulted in a decrease of contents of total and some amino acids (glutamine and asparagine) in developing seeds except for at the early maturation stage and in a decreased protein content of mature seeds. On the other hand, the N application led to faster accumulation of oil in developing seeds and to an increased oil content of mature seeds. Based on these results, it was concluded that the N application at the flowering stage changed the composition of solutes imported by developing seeds and resulted in variations in the contents of storage compounds. The results indicate that it is possible to improve seed quality by fine control of N application.  相似文献   
42.
Malic enzymes have been considered to play a key role in energy metabolism for nitrogenase reaction in bacteroids. To elucidate the physiological role of the malic enzymes in Bradyrhizobium japonicum bacteroids, a putative malic enzyme gene Bjtme1 was cloned by polymerase chain reaction (PCR) using degenerated primers from conserved regions of the protein sequences of bacterial malic enzymes and draft sequence data of the Bradyrhizobium japonicum USDA110 genome sequence project. To confirm the characteristics of the Bjtme1 gene, the protein encoded by this gene was over-expressed using a pET32a(+) system and it exhibited a NADP+-malic enzyme (EC 1.1.1.40) activity, indicating that Bjtme1 was the gene of the NADP+-malic enzyme. This is the first report on the cloning and characterization of the NADP+-malic enzyme gene from B. japonicum, and the gene structure was compared with that of NADP+-malic enzyme genes of other rhizobia.  相似文献   
43.

Background  

Students suffering from psychosomatic symptoms, including drowsiness and feelings of melancholy, often have basic lifestyle problems. The aim of this study was to investigate whether psychosomatic complaints may be related to circadian dysfunction.  相似文献   
44.
This paper describes the relationship between the egg vitamin concentrations and the egg quality in the Japanese eel Anguilla japonica . No notable relation was found between any vitamin and the fertilization rate. Hatching and survival rates of larvae, however, significantly increased with an elevated level of egg vitamin C (VC). In contrast to VC, the relation between vitamins E (VE) and A (VA) concentrations and survival rate showed a clear peak, with a reduced survival rate at both higher and lower vitamin concentrations. The ratio of VE to lipid or highly unsaturated fatty acid (HUFA) in eggs positively correlated with hatching and survival rates of larvae. High-quality (HQ) eggs were determined as eggs that produced larvae having a survival rate higher than 80% at 8 days post hatch, and low-quality (LQ) eggs were determined as eggs that did not hatch. The level of VC of HQ was significantly higher than LQ. The results of this study suggest that HQ eggs, which produce larvae having a high survival rate, must have high levels of VC and VE/HUFA ratio and contain optimum levels of VA and VE in Japanese eel.  相似文献   
45.
46.
47.
Of eight mongrel bitches, the antimesometrial side of the nonpregnant left horn of the uterus at the pregnant or nonpregnant luteal phase was scratched with a Kirschner's wire. Cystic endometrial hyperplasia (CEH) was induced in seven of the eight bitches (87.5%). No difference in the incidence of CEH in the left horn was seen between the pregnant and the nonpregnant groups. Histological examinations showed CEH with a dilatation of the basal glands, resembling "Swiss cheese endometrium".  相似文献   
48.
Procaterol (PCR) is a beta‐2‐adrenergic bronchodilator widely used in Japanese racehorses for treating lower respiratory disease. The pharmacokinetics of PCR following single intravenous (0.5 μg/kg) and oral (2.0 μg/kg) administrations were investigated in six thoroughbred horses. Plasma and urine concentrations of PCR were measured using liquid chromatography–mass spectrometry. Plasma PCR concentration following intravenous administration showed a biphasic elimination pattern. The systemic clearance was 0.47 ± 0.16 L/h/kg, the steady‐state volume of the distribution was 1.21 ± 0.23 L/kg, and the elimination half‐life was 2.85 ± 1.35 h. Heart rate rapidly increased after intravenous administration and gradually decreased thereafter. A strong correlation between heart rate and plasma concentration of PCR was observed. Plasma concentrations of PCR after oral administration were not quantifiable in all horses. Urine concentrations of PCR following intravenous and oral administrations were quantified in all horses until 32 h after administration. Urine PCR concentrations were not significantly different on and after 24 h between intravenous and oral administrations. These results suggest that the bioavailability of orally administrated PCR in horses is very poor, and the drug was eliminated from the body slowly based on urinary concentrations. This report is the first study to demonstrate the pharmacokinetic character of PCR in thoroughbred horses.  相似文献   
49.
50.
Twenty-six provenances (2 340 plants) of cork oak (Quercus suber spp.) originating from Portugal, Spain, Italy, Morocco, Algeria, and Tunisia were tested for genetic variation among and within provenances by growth traits. Seven morphometrical characters were measured in 90 plants from each provenance. Analysis of variance showed highly significant differences for all characters. The phenotypic coefficient of differentiation reached 0.24 for the form and 0.22 for height, thus revealing a strong structuring between the provenances. Comparative study of growth among the provenances revealed more vigorous growth and better survival rate for those from Morocco, Spain, and Portugal, which may constitute better materials for afforestation. Furthermore, this variability appeared to be geographically structured and would be mainly genetically controlled, as cork oak provenances were cultivated under the same environmental conditions. Our results should be helpful for guide forest managers in afforestation.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号