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   2158篇
  免费   129篇
  国内免费   11篇
林业   173篇
农学   131篇
基础科学   39篇
  491篇
综合类   159篇
农作物   289篇
水产渔业   205篇
畜牧兽医   468篇
园艺   83篇
植物保护   260篇
  2024年   4篇
  2023年   21篇
  2022年   75篇
  2021年   89篇
  2020年   100篇
  2019年   135篇
  2018年   153篇
  2017年   135篇
  2016年   139篇
  2015年   76篇
  2014年   90篇
  2013年   225篇
  2012年   123篇
  2011年   142篇
  2010年   114篇
  2009年   71篇
  2008年   123篇
  2007年   61篇
  2006年   50篇
  2005年   43篇
  2004年   36篇
  2003年   34篇
  2002年   27篇
  2001年   17篇
  2000年   27篇
  1999年   16篇
  1998年   15篇
  1997年   14篇
  1996年   17篇
  1995年   13篇
  1994年   7篇
  1993年   4篇
  1992年   8篇
  1991年   6篇
  1990年   9篇
  1989年   7篇
  1988年   4篇
  1987年   7篇
  1986年   6篇
  1985年   7篇
  1984年   9篇
  1983年   4篇
  1982年   2篇
  1981年   4篇
  1979年   5篇
  1975年   3篇
  1973年   3篇
  1972年   2篇
  1971年   3篇
  1967年   4篇
排序方式: 共有2298条查询结果,搜索用时 15 毫秒
21.
In this work we identified specific bovine leukocytes that were bound by the Mannheimia haemolytica adhesin molecule (MhA) and the biological effect on the leukocytes. Histochemical staining and flow cytometry showed that MhA bind neutrophils (90%) and monocytes (5%). MhA induced an oxidative response in purified neutrophils; this effect was 1.5-fold higher than the effect observed with control cells activated with Zymosan. Cellular binding by MhA was inhibited with GlcNAc and its oligomers, as well as by glycoproteins containing tri- and tetra-antennary N-glycosydically linked glycans. MhA-induced oxidative burst was significantly inhibited by GlcNAc, iodoacetamide, superoxide dismutase, and piroxicam (p<0.05). Our findings suggest that among bovine leukocytes, neutrophils are the main target for MhA, inducing production of oxidative radicals by non-opsonic mechanism that seem to play an important role in tissue damage during mannheimiosis.  相似文献   
22.
1. The single-copy domain of the N-terminal region of the vlhA gene of Mycoplasma synoviae was sequenced, analysed and verified and used to type Iranian field isolates of M. synoviae and the MS-H live vaccine strain. In addition, a restriction fragment length polymorphism (RFLP) method was developed to differentiate between field isolates of Iranian and MS-H vaccine strains.

2. All sequences were analysed and aligned; the percentage similarity of the DNA was calculated and dendrograms were constructed. Based on single nucleotide polymorphism (SNP) that existed in all field isolates in Iran, the PCR-RFLP method allowed the differentiation of all M. synoviae field isolates from the vaccine strain.

3. Using phylogenetic analysis, the isolates were assigned to 8 unique genotypes and, within each group, DNA had a high level of similarity.

4. DNA sequence analysis and PCR-RFLP of the amplicon based on percent similarity and evolutionary relationship appeared to be useful tools for strain differentiation whether M. synoviae clinical isolates from infected chickens were derived from the vaccine strain or wild-type strains.

5. This study confirms the potential value of strain typing for epidemiological purposes and suggests that phylogenetic studies are essential to understand the true relationships between strains.  相似文献   

23.
Animal rearing is the major occupation of most population of South Asian countries. Due to lack of resources and limited approach to modern medicine, most of the livestock raisers prefer to use plant-based traditional medicine also referred to as ethnoveterinary medicine (EVM). Indeed, the use of medicinal plants in South Asia dates back to several centuries with documented evidences. However, there is currently a dearth of documentation and compilation of use of medicinal plants for animal diseases in this part of the world. This review aims to provide an up-to-date compilation of common medicinal plants used for the treatment and/or management of common animal diseases in South Asian countries. Extensive literature search was conducted online and relevant data was retrieved from well-known scientific databases. A total of 276 plants belonging to 95 families have been documented to be in common use for managing 14 different categories of animal diseases. Solanaceae, Lamiaceae, Fabaceae, and Leguminosae were most common plant families in terms of their plant species used for EVM. Gastric diseases were commonly reported and accounted for 72 species of plants used for its treatment followed by the miscellaneous disorders category and skin diseases comprising of 65 and 39 plant species respectively. Herbs accounted for 46% of the total plant species, followed by trees (33%), and shrubs (18%). The EVM were applied through different routes of administration; oral administration accounted for 72% followed by topical application 27%, while burning of plant parts to create smoke around animals to repel insects was less common (1%). It is anticipated that the present review will stimulate further ethnoveterinary research among livestock disease management practices in South Asia.  相似文献   
24.
25.
The study was aimed to investigate the influence of animal age, post‐slaughter chilling rate, and aging time on meat quality of M. longissimus dorsi (LD) of water buffalo (Bubalus bubalis) and humped cattle (Bos taurus indicus) bulls. After slaughtering, one side of carcasses was subjected to rapid chilling (RC) (0 ± 2°C) and other side was hanged in controlled room temperature (25 ± 2°C) for 3 hr, then allowed to the chiller (0 ± 2°C). The meat quality traits were analyzed at 1, 7, and 14 days of storage. It was noted that rapidly chilled carcasses from the younger animals of both species missed the ideal pH/temperature window, which affects the toughness of the meat. Buffalo meat presented higher shear force, color L* values, and lower b* value as compared to the cattle meat. Moreover, meat shear force values decreased while all color coordinates and cooking loss values increased with lengthening the storage time in both age groups of cattle and buffalo. In conclusion, the tenderness of cattle meat was superior to that of buffalo and RC adversely affect the shear force values of young cattle and both age groups of buffalo bulls.  相似文献   
26.
Detection of antibodies against peste des petits ruminants virus in sera of cattle, camels, sheep and goats in Sudan.  相似文献   
27.
Eight clones of monoclonal antibodies (Mabs) to Nipah virus (NV) were produced against formalin-inactivated NV antigens. They reacted positive by indirect immunofluorescent antibody test, and one of them also demonstrated virus neutralizing activity. They were classified into six different types based on their biological properties. These Mabs will be useful for immunodiagnosis of NV infections in animals and further research studies involving the genomes and proteins of NV.  相似文献   
28.
The fluorescent antibody (FA) assay was developed for detecting the stunting syndrome agent (SSA) from intestinal tissue. Similarly, the indirect fluorescent antibody (IFA) assay was developed for detecting serum antibodies to SSA. Convalescent antiserum from turkeys orally immunized with SSA was found to be the primary antibody of choice for the FA assay. Intestinal jejunal samples from poults inoculated 3-4 days postinoculation (DPI) was found to be the best antigen source for the IFA assay. SSA was detected from the intestinal tracts of experimentally inoculated birds at 2 DPI with highest level of reactivity at 3 DPI by the FA assay. After 4 DPI the level of SSA infectivity of the intestines waned to low levels. Serum antibody was detected from experimentally inoculated birds as early as 7 DPI with all birds tested seroconverting by 12 DPI. These assays should prove useful for future studies concerning stunting syndrome.  相似文献   
29.
30.
This study compares the factors associated with variable interval to oestrus and ovulation between early versus late ovulating goats following PGF administration. The time of ovulation in Beetal goats (n = 38) was monitored through transrectal ultrasound at every 6 hr following a single dose of PGF (experiment 1). Variations in oestrus and ovulation times were further explored through the changes in follicular dynamics, endocrine profiles and behaviour in another set of goats (n = 13) following single PGF given randomly during the luteal phase (experiment 2). The ovulation time varied between 60 and 96 hr, and 57% of ovulations occurred by 72 hr following PGF (experiment 1). Accordingly, the goats (n = 13) in the second experiment were retrospectively divided either into early and/or late ovulating, that is, ≤72 and/or ≥84 hr following PGF. The onset of oestrus, peak estradiol‐17β concentration and LH surge after PGFwas first observed in early than late ovulating goats (p < 0.05). The goats ovulating early had larger follicle and smaller CL in diameter at the time of PGF administration than those ovulating late (5.4 ± 0.2 vs. 4.3 ± 0.2 mm and 10 ± 0.6 vs. 11.8 ± 0.3 mm, respectively; p < 0.05). Likewise, plasma progesterone concentration tended to be lower (p = 0.087) in early than late ovulating goats. In conclusion, the size of dominant follicle and CL at the time of PGF2a determines the interval to ovulation following a single dose of PGF2a during the luteal phase.  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