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   333篇
  免费   16篇
林业   35篇
农学   16篇
  86篇
综合类   16篇
农作物   19篇
水产渔业   43篇
畜牧兽医   71篇
园艺   17篇
植物保护   46篇
  2024年   2篇
  2023年   4篇
  2022年   1篇
  2021年   7篇
  2020年   11篇
  2019年   13篇
  2018年   15篇
  2017年   16篇
  2016年   19篇
  2015年   13篇
  2014年   11篇
  2013年   21篇
  2012年   25篇
  2011年   27篇
  2010年   15篇
  2009年   12篇
  2008年   16篇
  2007年   17篇
  2006年   15篇
  2005年   15篇
  2004年   6篇
  2003年   9篇
  2002年   14篇
  2001年   2篇
  2000年   1篇
  1999年   2篇
  1998年   1篇
  1997年   4篇
  1996年   3篇
  1993年   3篇
  1992年   3篇
  1991年   2篇
  1990年   5篇
  1988年   3篇
  1987年   3篇
  1986年   2篇
  1985年   3篇
  1984年   1篇
  1981年   1篇
  1980年   2篇
  1979年   1篇
  1977年   1篇
  1974年   2篇
排序方式: 共有349条查询结果,搜索用时 15 毫秒
61.
The aim of the study was to confirm the presence of rutin, one of the most common quercetin glycosides, and other quercetin derivatives in plants of genus Amaranthus, to investigate the influence of the species and variety on rutin distribution in the plant and content changes during growing season. The rutin content was determined by micellar electrokinetic capillary chromatography in individual plant parts at the beginning of the growth, at the flowering stage and at the maturity stage of five Amaranthus species. The total quercetin content was determined by micellar electrokinetic capillary chromatography too. The rutin content in amaranth ranged from 0.08 (in seeds) to 24.5 g/kg dry matter (in leaves). Comparison of the determined total quercetin content and the calculated content of quercetin released from rutin did not prove important presence of quercetin or other quercetin derivatives than rutin. Only amaranth leaves sampled at the maturity stage probably contained quercetin or quercetin derivatives. Significant differences in the rutin content were established among species and as well varieties. Amaranthus hybrid and A. cruentus were the best sources of rutin.  相似文献   
62.
Residues of the insect growth regulator diflubenzuron were quantified on horse chestnut (Aesculus hippocastanum L.) leaves treated with a diflubenzuron 480 g litre?1 SC, Dimilin. To analyse the samples, an analytical procedure was developed involving a simple extraction step followed by high‐performance liquid chromatography on an octadecyl‐modified silica column with methanol + 0.01 M ammonium acetate mobile phase. The results showed diflubenzuron to be highly stable on horse chestnut leaves; more than 4 months (127 days) after application, 38% (on average) of the insecticide still remained on/in the leaves. The data confirmed biological observations showing diflubenzuron's long‐term efficacy against the horse chestnut leafminer, Cameraria ohridella Deschka & Dimi?, which is the most important pest of the horse chestnut in Europe. The hypothesis of possible penetration of diflubenzuron into the leaf mass is explored and discussed. Copyright © 2006 Society of Chemical Industry  相似文献   
63.
The secondary osmoregulatory canals in the scolex and neck region of Silurotaenia siluri, a parasite of the catfish Silurus glanis (L.), terminate below the tegument basal plasma membrane. The basal plasma membrane of the osmoregulatory canal syncytium is in tight contact with the tegument basal plasma membrane.  相似文献   
64.
65.
Columnar growth in apples can have considerable positive consequences for orchard maintenance, but the lack of columnar cultivars producing fruits with desired market quality prevents their broader utilization in orchards. New crossings focused on their breeding are therefore conducted throughout the world every year. Unfortunately, the reliable discrimination between columnar growth and normal phenotype is difficult until seedlings are 2–3 years of age. However, molecular marker–assisted selection (MAS) can be used in seedlings several weeks old providing immense help in breeding programmes focused on columnar apple production. Here, we describe a rapid and reliable method for the detection of both wild-type (WT) and columnar (Co) alleles originating from ‘McIntosh Wijcik’ in a single reaction using a real-time PCR allelic discrimination approach. Our assay was tested in 130 genotypes (80 normal and 50 columnar habit) from various crossings and their parents, and in all cases, genotype corresponded to phenotype. The assay is thus suitable for laboratories interested in high-throughput MAS for columnar tree habit breeding.  相似文献   
66.
67.
The aim of the present study was to estimate the absorption of 125I-labeled proinflammatory cytokines--interleukin-1beta (IL-1beta), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) from inflamed porcine uterus into the uterine venous blood. Moreover, in order to test the hypothesis that the above cytokines penetrate directly into ovaries and oviduct via local destination transfer in the area of the ovarian vascular pedicle and bypassing the systemic circulation, the concentration of IL-1beta, IL-6 and TNF-alpha in ovarian and oviductal tissues was also studied. These cytokine concentrations were also estimated in the ovarian venous blood. IL-1beta, IL-6 and TNF-alpha from both control and inflamed uteri were absorbed into the uterine venous blood, but it was higher (P < 0.05-0.001) from the pathologically changed uteri. The uterine tissues, particularly the endometrium, of both control and inflamed uteri retained all studied cytokines, but to a higher degree (P < 0.001) in the inflamed uteri. Injections of IL-1beta, IL-6 and TNF-alpha into the control and inflammatory changed uteri produced the presence of these proteins in the ovary and oviduct. However, the concentrations of IL-1beta and IL-6 in the ovarian and oviductal tissues was low after injections of control and inflamed uteri with these cytokines. In turn, administration of TNF-alpha into the inflammatory changed uteri lead to an enhancement in the concentration of this cytokine in the ovarian parenchyma (P < 0.05) and oviduct (P < 0.001). All studied cytokines were found in the ovarian venous blood after their injection into both control and inflamed uteri, which indicated its local destination transfer to the ovary. However, the concentration of cytokines increased (P <0.05-0.001) in the gilts with pathologically changed uteri as compared to controls. The study showed that both control and inflamed porcine uteri absorbed IL-1beta, IL-6 and TNF-alpha into the uterine venous blood, but the values of absorbed cytokines from inflamed uteri were higher. Moreover, the quantity and the manner of the studied cytokineS absorption into the uterine venous blood differed.  相似文献   
68.
Preface     
  相似文献   
69.
A quantitative RT real-time PCR method was developed for the detection and quantification of Tomato mosaic virus (ToMV) in irrigation waters. These have rarely been monitored for the presence of plant pathogenic viruses, mostly due to the lack of efficient and sensitive detection methods. The newly developed method presented here offers a novel approach in monitoring the health status of environmental waters. ToMV was reliably detected at as low as 12 viral particles per real-time PCR reaction, which corresponds to the initial concentration of approximately 4.2 × 10?10 mg (6,300 viral particles) of ToMV per ml of sample. The sensitivity of the method was further improved by including the Convective Interaction Media® (CIM) monolithic chromatographic columns for quick and efficient concentration of original water samples. Seven out of nine water sources from different locations in Slovenia tested positive for ToMV, after concentrating the sample. Four samples tested ToMV-positive without the concentrating procedure. The presence and integrity of infective ToMV particles in the original sample, as well as in the chromatographic fraction, was confirmed using different methods from test plants, DAS ELISA to electron microscopy and real-time PCR. In this study, we propose a unique and simple diagnostic scheme for rapid, efficient, and sensitive monitoring of irrigation waters that could also be adopted for other plant, human or animal viruses.  相似文献   
70.
Phytoplankton blooms characterize temperate ocean margin zones in spring. We investigated the bacterioplankton response to a diatom bloom in the North Sea and observed a dynamic succession of populations at genus-level resolution. Taxonomically distinct expressions of carbohydrate-active enzymes (transporters; in particular, TonB-dependent transporters) and phosphate acquisition strategies were found, indicating that distinct populations of Bacteroidetes, Gammaproteobacteria, and Alphaproteobacteria are specialized for successive decomposition of algal-derived organic matter. Our results suggest that algal substrate availability provided a series of ecological niches in which specialized populations could bloom. This reveals how planktonic species, despite their seemingly homogeneous habitat, can evade extinction by direct competition.  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