全文获取类型
收费全文 | 20485篇 |
免费 | 236篇 |
国内免费 | 524篇 |
专业分类
林业 | 4311篇 |
农学 | 2025篇 |
基础科学 | 401篇 |
3358篇 | |
综合类 | 1888篇 |
农作物 | 2330篇 |
水产渔业 | 1929篇 |
畜牧兽医 | 1589篇 |
园艺 | 1234篇 |
植物保护 | 2180篇 |
出版年
2024年 | 11篇 |
2023年 | 43篇 |
2022年 | 104篇 |
2021年 | 183篇 |
2020年 | 156篇 |
2019年 | 155篇 |
2018年 | 2856篇 |
2017年 | 2823篇 |
2016年 | 1299篇 |
2015年 | 266篇 |
2014年 | 193篇 |
2013年 | 203篇 |
2012年 | 1021篇 |
2011年 | 2373篇 |
2010年 | 2385篇 |
2009年 | 1479篇 |
2008年 | 1517篇 |
2007年 | 1771篇 |
2006年 | 230篇 |
2005年 | 252篇 |
2004年 | 199篇 |
2003年 | 239篇 |
2002年 | 146篇 |
2001年 | 123篇 |
2000年 | 142篇 |
1999年 | 118篇 |
1998年 | 146篇 |
1997年 | 115篇 |
1996年 | 101篇 |
1995年 | 84篇 |
1994年 | 78篇 |
1993年 | 88篇 |
1992年 | 58篇 |
1991年 | 63篇 |
1990年 | 56篇 |
1989年 | 39篇 |
1988年 | 45篇 |
1987年 | 20篇 |
1986年 | 11篇 |
1985年 | 11篇 |
1984年 | 7篇 |
1983年 | 5篇 |
1982年 | 9篇 |
1981年 | 7篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1977年 | 4篇 |
1969年 | 1篇 |
1968年 | 4篇 |
1967年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Characterization of Doayo and Kapsiki taurine cattle breeds of Cameroon in their natural environment
Data were collected on live weight (LW), heart girth (HG), height-at-withers (HW), trunk length (TL), age, sex, and coat color
of 207 taurines cattle—122 of the Doayo (Namchi) breed and 85 of the Kapsiki (Kirdi) breed. The animals, aged 1 to 20 years,
were selected from 60 herds randomly selected from villages of Poli of Faro and Mokolo of Tsanga, divisions of the North and
Far North Regions of Cameroon. The data were analyzed using the SAS program with a linear model, applying standard tests.
Results indicated no breed effect (P > 0.05) in the growth trends of LW, HG, HW, and TL. HG and TL were highly significantly (P < 0.0001) related to LW. The growth pattern for the two breeds was the same since the linear contrast of least square means
for the traits at various age groups did not differ (P > 0.05) significantly. The breeds attained maturity as from 4 years. In the absence of breed effect (P > 0.05), a single regression equation was established for the estimation of live weight as thus LW = - 244.42 ( ±22.57 ) kg + 2.49 ( ±0.23 ) HG + 1.04 ( ±0.25 ) TL {\hbox{LW}} = - {244}.{42 }\left( {\pm {22}.{57}} \right){\hbox{ kg}} + {2}.{49 }\left( {\pm 0.{23}} \right){\hbox{ HG}} + {1}.0{4 }\left( {\pm 0.{25}} \right){\hbox{ TL}} , with HG contributing up to 70% of total variation and TL, 2%. This equation could be used to develop a measuring band useful
in the rural environment for commercial and clinical veterinary purposes. 相似文献
62.
Canine Haematopoietic Chimerism Analyses by Semiquantitative Fluorescence Detection of Variable Number of Tandem Repeat Polymorphism 总被引:1,自引:0,他引:1
Hilgendorf I Weirich V Zeng L Koppitz E Wegener R Freund Junghanss C 《Veterinary research communications》2005,29(2):103-110
Canine models are successfully applied to the study of haematopoietic stem cell transplantation (HSCT). Monitoring of haematopoietic donor/recipient chimerism is of major significance in detecting and quantifying engraftment or graft rejection of the donor-derived haematopoietic cells after transplantation. Radioactive analyses of polymorphic microsatellite markers are commonly used for chimerism analyses. We describe an improved, non-isotopic method that is based on the analysis of microsatellite markers in donor and recipient cells using capillary electrophoresis and fluorescence detection. Artificial mixtures of donor and recipient DNA that were generated from peripheral blood mononuclear cells from dog leukocyte antigen-identical siblings were used to analyse the sensitivity of the assay. DNA from dogs that had received HSCT were also analysed in order to demonstrate the feasibility of the method in vivo. For chimerism analyses, six different microsatellite loci were systematically amplified using fluorescent PCR primer. The fluorescent polymerase chain reaction products were separated by capillary electrophoresis using POP4 on a 310 ABI Prism Genetic Analyzer. After electrophoresis, fluorescence signals were automatically sized and quantified using GeneScan software. The method described provides an accurate assessment of haematopoietic chimerism in the canine model with significantly reduced hands-on time compared to conventional gel electrophoresis. 相似文献
63.
Twelve male buffalo calves of 10 to 12 months of age were divided into 3 groups of four each. They were fed wheat straw+concentrate
mixture +3 Kg greens. The chemical composition of the diet was same in all the three groups except fluoride which was added
(as NaF) in concentrate mixture of group B and C to make the final fluoride concentration 30 ppm and 60 ppm respectively.
The animals were kept on scheduled diet for a period of 90 days. Body weights were recorded at the start of the experiment
and at fortnightly interval thereafter. Analysis of data revealed that the dry matter intake decreased non significantly in
group B and C as compared to control group. A significant decrease in serum calcium and a significant increase in phosphorus
concentration were observed in group C animals. A significant increase was observed in alkaline phosphatase activity in group
C animals. A non significant decrease was observed in T4 values in group C animals. On the basis of these results it could be concluded that fluoride in the diet of buffalo calves
@ 30 ppm is a safe level whereas 60 ppm has affected the blood metabolites. 相似文献
64.
65.
66.
Tatsuya Nakayama Michio Jinnai Ryuji Kawahara Khong Thi Diep Nguyen Nam Thang Tran Thi Hoa Le Kieu Hanh Pham Ngoc Khai Yoshinori Sumimura Yoshimasa Yamamoto 《Tropical animal health and production》2017,49(1):31-37
Reports of livestock infections with extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-E) are increasing. Based on interviews conducted over a 6-month period, we found that veterinarians in the Vietnamese province of Thai Binh prefer to prescribe colistin-based drugs (CBD) in chicken farms. We aimed to clarify whether CBD use selects for strains of colistin-resistant ESBL-E. With the cooperation of seven local households, we detected ESBL-E in chickens’ feces after treating chickens with CBD. Phylogenetic groupings and the presence of CTX-M/AmpC genes were determined, and the multi-antibiotic susceptibility of isolates was analyzed. Our results showed that ESBL-E presented in seven chickens’ feces from two households. Seventy-two percent of ESBL-E isolates harbored CTX-M9 and the phylogenetic group A; the colistin minimum inhibitory concentration (MIC) of all isolated ESBL-E ranged from 0.064 to 1 μg mL?1. Moreover, ESBL-E isolates were used to experimentally select for colistin resistance, and the effect of commercial CBD on ESBL-E was investigated. The results showed that an ESBL-E strain with a colistin MIC of 4 μg mL?1 was able to grow in media with CBD. Although CBD treatment was effective, in vitro experiments demonstrated that ESBL-E can easily acquire colistin resistance. Therefore, restrictions on colistin use are necessary to prevent the emergence of colistin-resistant bacteria. 相似文献
67.
Cyanobacteria are important components of the lowland rice ecosystem. Therefore, it is important to examine the effect of
herbicides (commonly used against weeds of rice crop) on the performance of cyanobacteria. We studied the toxic effects of
three herbicides often used in rice field, viz. propanil, pretilachlor and glyphosate, on the performance traits of Anabaena fertilissima C.B. Rao. Pretilachlor [0–40 active ingredient (ai) mg/L] and glyphosate (0–80 ai mg/L) exhibited toxicity to A. fertilissima at higher doses than propanil (0–1.5 mg/L). Propanil had severe damaging effects on cellular characteristics of A. fertilissima when compared to pretilachlor or glyphosate. Propanil treatment of A. fertilissima resulted in the leakage of protoplast from the heterocyst due to the breakage of the plasma membrane and surrounding wall.
Our study shows that photosystem II herbicides such as propanil could have deleterious effects on phototrophic (cyanobacterial)
communities, which are an integral part of the rice ecosystem. 相似文献
68.
Shanoo Suroowan Faisal Javeed Mushtaq Ahmad Muhammad Zafar Mehwish Jamil Noor Sadaf Kayani Ali Javed Mohamad Fawzi Mahomoodally 《Veterinary research communications》2017,41(2):147-168
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
69.
Aklilu HA Almekinders CJ Udo HM Van der Zijpp AJ 《Tropical animal health and production》2007,39(3):165-177
This study aimed to examine village poultry consumption and marketing in Ethiopia in relation to gender, socio-cultural events
and market access. The main objects of the research were producers, poultry markets, producer-sellers, and intermediary sellers
in three locations representing different levels of market access in Tigray. About 3000 farm records were collected over a
period of 12 months from 131 producers to obtain quantitative data on sales and consumption. Ninety-three semi-structured
interviews with 58 producer-sellers and 35 intermediaries and 12 group discussions with these market actors were conducted
to explore organization, price dynamics and socio-cultural aspects of poultry marketing. In total, 928 producer-sellers and
225 intermediaries were monitored monthly to examine participation by gender in poultry marketing. Better market access was
associated with a shorter market chain and higher prices for the producers. Female-headed households had smaller poultry sales
and consumption per household but sale and consumption per family member were 25% and 66% higher, respectively, than in male-headed
households. While women dominated in the producer-sellers group, intermediaries were mainly men. Religious festivals periodically
shifted local demand and prices of poultry. To improve the benefit of poultry keeping, poverty-stricken households may profit
from better market access through better market information, infrastructure, market group formation and careful planning to
match the dynamics in demand. 相似文献
70.
Leonard Omadang Martin Chamai Emmanuel Othieno Andrew Okwi Francis Olaki Inangolet Francis Ejobi Peter Oba Michael Ocaido 《Tropical animal health and production》2018,50(1):11-17
A cross-sectional study was done from March 2013 to May 2014 to assess knowledge, attitudes, and practices towards cystic echinococcosis (CE) or hydatidosis among selected pastoral and agro-pastoral communities in Uganda. A structured questionnaire was administered to 381 respondents. Multivariate logistic regression analysis was done to find the relationship between knowledge about CE and factors such as age, sex, and level of education across all regions. The odds ratio and confidence interval were used to determine the difference in responses across regions. It was shown that age above 36 years was significantly (p < 0.001) associated with awareness about CE in livestock. Likewise, uneducated (p < 0.0001) and agro-pastoralists (p = 0.01) were significantly less knowledgeable than the educated and pastoralists across all regions. The overall knowledge towards CE in livestock was low 17.8% (95% CI = 14.0–21.6). Dog ownership was high and they never dewormed their freely roaming dogs. Dogs shared water with livestock. In conclusion, knowledge about CE in livestock was low across all regions. Therefore, public health education and formulation of policies towards its control by the relevant stakeholders should be done. Also, the true prevalence of CE in livestock needs to be done so that the magnitude and its public health significance are elucidated. 相似文献