全文获取类型
收费全文 | 5922篇 |
免费 | 294篇 |
国内免费 | 151篇 |
专业分类
林业 | 359篇 |
农学 | 413篇 |
基础科学 | 92篇 |
1051篇 | |
综合类 | 727篇 |
农作物 | 782篇 |
水产渔业 | 483篇 |
畜牧兽医 | 2037篇 |
园艺 | 101篇 |
植物保护 | 322篇 |
出版年
2024年 | 7篇 |
2023年 | 39篇 |
2022年 | 127篇 |
2021年 | 215篇 |
2020年 | 154篇 |
2019年 | 174篇 |
2018年 | 184篇 |
2017年 | 189篇 |
2016年 | 206篇 |
2015年 | 200篇 |
2014年 | 260篇 |
2013年 | 334篇 |
2012年 | 412篇 |
2011年 | 477篇 |
2010年 | 292篇 |
2009年 | 278篇 |
2008年 | 391篇 |
2007年 | 367篇 |
2006年 | 333篇 |
2005年 | 282篇 |
2004年 | 241篇 |
2003年 | 221篇 |
2002年 | 168篇 |
2001年 | 156篇 |
2000年 | 127篇 |
1999年 | 89篇 |
1998年 | 63篇 |
1997年 | 33篇 |
1996年 | 30篇 |
1995年 | 33篇 |
1994年 | 24篇 |
1993年 | 32篇 |
1992年 | 31篇 |
1991年 | 29篇 |
1990年 | 36篇 |
1989年 | 23篇 |
1988年 | 11篇 |
1987年 | 10篇 |
1986年 | 9篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1983年 | 6篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1978年 | 11篇 |
1974年 | 5篇 |
1972年 | 5篇 |
1970年 | 3篇 |
1969年 | 3篇 |
1968年 | 4篇 |
排序方式: 共有6367条查询结果,搜索用时 15 毫秒
21.
Glutathione content of in vivo and in vitro matured canine oocytes collected from different reproductive stages 总被引:3,自引:0,他引:3
Kim MK Hossein MS Oh HJ Fibrianto HY Jang G Kim HJ Hong SG Park JE Kang SK Lee BC 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2007,69(6):627-632
Glutathione (GSH) concentrations of oocytes are considered as an important marker of the cytoplasmic maturation. The present study was designed to compare GSH concentrations of in vivo and in vitro matured canine oocytes. In vivo matured oocytes were collected 72 hr after ovulation by flushing fallopian tubes after laparotomy. Ovaries were collected from bitches with different reproductive stages, and collected oocytes were divided into 2 groups according to the size viz. < 120 microm and > 120 microm in diameter and cultured for 72 hr in Tissue Culture Medium-199 supplemented with 10% FBS, 2.2 mg/ml sodium bicarbonate, 2.0 microg/ml estrogen, 0.5 microg/ml FSH, 0.03 IU/ml hCG, and 1% penicillin-streptomycin solution in the presence or absence of 50 microM beta-mercaptoethanol. GSH concentrations were determined by the dithionitrobenzoic acid-glutathione disulfide (DTNB-GSSG) reductase recycling assay. GSH concentrations of immature canine oocytes were 2.9 and 3.8, 3.5 and 6.8, and 3.1 and 6.5 pM/oocyte for < 120 microm and > 120 microm in diameter oocyte groups at anestrous, follicular and luteal stage, respectively (P<0.05). In vivo matured oocytes had significantly higher GSH concentrations compared with in vitro matured oocytes. The GSH content was 19.2 pM/oocyte for in vivo matured oocytes, while 4.1 to 8.1 and 5.7 to 13.2 pM/oocyte for in vitro matured oocytes cultured in the absence or presence of beta-mercaptoethanol, respectively (P<0.05). Presence of beta-mercaptoethanol increased GSH synthesis in canine oocytes cultured in vitro, and oocytes collected from follicular and luteal stage was superior to anestrus oocytes. 相似文献
22.
Jeong-Hyeon Cho Seunghyung Lee Bong-Joo Lee Sang-Woo Hur Kang-Woong Kim Maeng-Hyun Son Dong-Jae Yoo 《动物营养(英文)》2021,7(2):548
An 8-week feeding trial was conducted to determine the optimal dietary protein level for juvenile marbled flounder. Five semi-purified test diets were formulated to contain different protein levels (CP) including 42.7%, 47.4%, 53.3%, 58.8%, and 64.5% (dry matter), named as CP42.7, CP47.4, CP53.3, CP58.8, and CP64.5, respectively. Five hundred and twenty-five juveniles (6.0 ± 0.1 g) were randomly distributed into 15 tanks (300 L tanks), resulting in 35 fish per tank (n = 3 tanks). Fish were fed the test diets 5 times per day until satiation. The CP58.8 resulted in the highest gain in weight and the best efficiency in feed utilization among the tested protein levels (P < 0.05). Fish fed the CP58.8 diet showed significantly higher whole-body protein and lipid contents than the fish that were fed the other diets (P < 0.05). Fish fed the CP53.3, CP58.8, and CP64.5 diets showed a significantly higher dorsal-muscle lipid content than the fish that were fed the CP42.7 and CP47.4 diets (P < 0.05). The one-slope straight broken-line regression analysis on the results of the thermal growth coefficient and feed conversion ratio indicated that the estimated optimum dietary protein level was 58.8%. Taken together, it is suggested that the dietary protein level of 58.8% is optimal for better growth and high efficiency in feed utilization for the juvenile marbled flounder. 相似文献
23.
Effects of xylanase supplementation on growth performance,nutrient digestibility,blood parameters,fecal microbiota,fecal score and fecal noxious gas emission of weaning pigs fed corn‐soybean meal‐based diet 下载免费PDF全文
This study was conducted to evaluate the effects of xylanase supplementation on nutrient digestibility, growth performance, blood parameters, fecal microflora shedding, fecal score and fecal noxious gas emission of weaning pigs fed corn‐soybean meal based diet. A total of 150 weaning pigs with an average initial body weight (BW) of 7.85 ± 0.93 kg were randomly allocated to three treatments based on BW and sex (10 replicate pens with five pigs, two gilts and three barrows) were used in this 42‐day trial. Dietary treatments were: (1) CON, basal diet; (2) X1, basal diet +0.005% xylanase; (2) X2, basal diet +0.01% xylanase. The xylanase supplementation linearly increased (P < 0.05) average daily gain (ADG), and gain : feed ratio (G:F) from days 29 to 42 and the in overall period, dry matter, nitrogen and energy digestibility, and fecal Lactobacilli counts, and linearly decreased (P < 0.05) blood urea nitrogen (BUN) concentration, fecal NH3 and H2S emission. Additionally, at weeks 5 and 6, there was a linear decrease in fecal score with xylanase supplementation. In conclusion, dietary supplementation of xylanase improved growth performance, nutrient digestibility, shifted microbiota by increasing fecal Lactobacillus counts, decreased BUN concentration, fecal score, and fecal NH3 and H2S emission in weaning pigs. 相似文献
24.
Mark K. Asplen Gianfranco Anfora Antonio Biondi Deuk-Soo Choi Dong Chu Kent M. Daane Patricia Gibert Andrew P. Gutierrez Kim A. Hoelmer William D. Hutchison Rufus Isaacs Zhi-Lin Jiang Zsolt Kárpáti Masahito T. Kimura Marta Pascual Christopher R. Philips Christophe Plantamp Luigi Ponti Gábor Vétek Heidrun Vogt Vaughn M. Walton Yi Yu Lucia Zappalà Nicolas Desneux 《Journal of pest science》2015,88(3):469-494
25.
Krishnan HB Jang S Kim WS Kerley MS Oliver MJ Trick HN 《Journal of agricultural and food chemistry》2011,59(4):1223-1228
Legumes, including soybeans ( Glycine max ), are deficient in sulfur-containing amino acids, which are required for the optimal growth of monogastric animals. This deficiency can be overcome by expressing heterologous proteins rich in sulfur-containing amino acids in soybean seeds. A maize 27 kDa γ-zein, a cysteine-rich protein, has been successfully expressed in several crops including soybean, barley, and alfalfa with the intent to biofortify these crops for animal feed. Previous work has shown that the maize 27 kDa zein can withstand digestion by pepsin and elicit an immunogenic response in young pigs. By use of sera from patients who tested positive by ImmunoCAP assay for elevated IgE to maize proteins, specific IgE binding to the 27 kDa γ-zein is demonstrated. Bioinformatic analysis using the full-length and 80 amino acid sliding window FASTA searches identified significant sequence homology of the 27 kDa γ-zein with several known allergens. Immunoblot analysis using human serum that cross-reacts with maize seed proteins also revealed specific IgE-binding to the 27 kDa γ-zein in soybean seed protein extracts containing the 27 kDa zein. This study demonstrates for the first time the allergenicity potential of the 27 kDa γ-zein and the potential that this protein has to limit livestock performance when used in soybeans that serve as a biofortified feed supplement. 相似文献
26.
Methane emissions from different vegetation zones in a Qinghai-Tibetan Plateau wetland 总被引:1,自引:0,他引:1
Mitsuru Hirota Yanhong Tang Shigeki Hirata Wenhong Mo Shigeru Mariko 《Soil biology & biochemistry》2004,36(5):737-748
We measured methane (CH4) emissions in the Luanhaizi wetland, a typical alpine wetland on the Qinghai-Tibetan Plateau, China, during the plant growth season (early July to mid-September) in 2002. Our aim was to quantify the spatial and temporal variation of CH4 flux and to elucidate key factors in this variation. Static chamber measurements of CH4 flux were made in four vegetation zones along a gradient of water depth. There were three emergent-plant zones (Hippuris-dominated; Scirpus-dominated; and Carex-dominated) and one submerged-plant zone (Potamogeton-dominated). The smallest CH4 flux (seasonal mean=33.1 mg CH4 m−2 d−1) was observed in the Potamogeton-dominated zone, which occupied about 74% of the total area of the wetland. The greatest CH4 flux (seasonal mean=214 mg CH4 m−2 d−1) was observed in the Hippuris-dominated zone, in the second-deepest water area. CH4 flux from three zones (excluding the Carex-dominated zone) showed a marked diurnal change and decreased dramatically under dark conditions. Light intensity had a major influence on the temporal variation in CH4 flux, at least in three of the zones. Methane fluxes from all zones increased during the growing season with increasing aboveground biomass. CH4 flux from the Scirpus-dominated zone was significantly lower than in the other emergent-plant zones despite the large biomass, because the root and rhizome intake ports for CH4 transport in the dominant species were distributed in shallower and more oxidative soil than occupied in the other zones. Spatial and temporal variation in CH4 flux from the alpine wetland was determined by the vegetation zone. Among the dominant species in each zone, there were variations in the density and biomass of shoots, gas-transport system, and root-rhizome architecture. The CH4 flux from a typical alpine wetland on the Qinghai-Tibetan Plateau was as high as those of other boreal and alpine wetlands. 相似文献
27.
A total of 2053 import and 164 export samples from 425 production plants were examined over a 9-year period (1992-2000) for the presence of Listeria monocytogenes (L. monocytogenes) in Switzerland. Overall, 282 samples (12.2%) and 85 plants (20.5%) harbored the pathogen. The highest isolation risk was for marinated fish (38%); the lowest was in cured- and dried-meat products.Unconditional fixed-effect logistic regression was used to identify the main hazards associated with the presence of L. monocytogenes. The plant-level model considered potential risk factors for a positive culture operating at the production-plant level by including a random effect of plant and year.Food category was the only significant factor; sampling site, country of origin and season were not significant. Marinated fish was a strong predictor for positive culture, whereas cooked- and cured-meat products were protective. Plant and year effects were significant. Control measures should be focused on specific food items in each production plant. 相似文献
28.
Ji Hyeon Ahn Joon Ha Park In Hye Kim Jae-Chul Lee Bing Chun Yan Min Sik Yong Choong Hyun Lee Jung Hoon Choi Ki-Yeon Yoo In Koo Hwang Seung Myung Moon Hyung-Cheul Shin Moo-Ho Won 《Journal of veterinary science (Suw?n-si, Korea)》2014,15(3):335-342
Melatonin affects diverse physiological functions through its receptor and plays an important role in the central nervous system. In the present study, we compared immunoreactivity patterns of arylalkylamine N-acetyltransferase (AANAT), an enzyme essential for melatonin synthesis, and melatonin receptor type 1B (MT2) in the spinal cord of young adult (2~3 years) and aged (10~12 years) beagle dogs using immunohistochemistry and Western blotting. AANAT-specific immunoreactivity was observed in the nuclei of spinal neurons, and was significantly increased in aged dog spinal neurons compared to young adult spinal neurons. MT2-specific immunoreactivity was found in the cytoplasm of spinal neurons, and was predominantly increased in the margin of the neuron cytoplasm in aged spinal cord compared to that in the young adult dogs. These increased levels of AANAT and MT2 immunoreactivity in aged spinal cord might be a feature of normal aging and associated with a feedback mechanism that compensates for decreased production of melatonin during aging. 相似文献
29.
Yi-Suk Joo Soo-hwan An Ok-Kyung Kim Juan Lubroth Jung-Hyang Sur 《Canadian journal of veterinary research》2002,66(2):122-124
On March 20, 2000, a suspected vesicular disease in cattle was reported to the National Veterinary Research and Quarantine Service (NVRQS) of the Republic of Korea. This represented the index case of a foot-and-mouth disease (FMD) outbreak, which spread through several provinces. The Republic of Korea had been free of FMD for 66 years prior to the reintroduction of the virus and had recently suspended imports of pork and pork products from neighboring Japan owing to a reported FMD outbreak in that country. The Korean outbreak was ultimately controlled through the combination of preemptive slaughter, animal movement restrictions, and a strategy of ring vaccination. The purpose of this paper is to review the current FMD situation in Korea in the aftermath of its 2000 epizootic and how it may affect future efforts to eradicate or reduce risk of reintroduction of the disease into Korea. 相似文献
30.
Hyunseok Kim Min Jang Chi Won Shin Hyungjoo Han Jeesoo Cha Inhyung Lee Won-gyun Son 《Veterinary anaesthesia and analgesia》2021,48(1):92-100
ObjectiveTo describe an approach for ethmoidal nerve block (EBLOCK) and to compare the effects of a maxillary nerve block (MBLOCK), EBLOCK and their combination (M-EBLOCK) on heart rate (HR), systolic (SAP), mean (MAP), diastolic (DAP) arterial pressures and respiratory rate (fR) during nasal stimulation in dogs.Study designProspective, blinded, randomized, crossover placebo-controlled study.AnimalsBeagle dogs (five cadavers, nine live dogs), with a median (interquartile range) weight of 10.5 (10.3–11.0) kg.MethodsThe accuracy of iohexol injections (each 1 mL) at the maxillary and ethmoidal foramina in cadavers was evaluated using computed tomography. Then, anesthetized dogs were administered four bilateral treatments separated by 1 week, saline or 2% lidocaine 1 mL per injection: injections of saline at the maxillary and ethmoidal foramina (Control), injections of lidocaine at the maxillary foramina and saline at the ethmoidal foramina (MBLOCK), injections of saline at the maxillary foramina and lidocaine at the ethmoidal foramina (EBLOCK) and injections of lidocaine at all foramina (M-EBLOCK). The ventral nasal meatus was bilaterally stimulated using cotton swabs, and HR, SAP, MAP, DAP and fR were continuously recorded. Values for each variable were compared before and after stimulation using Wilcoxon signed-rank test. Changes in variables among treatments were analyzed using Mann–Whitney U and Kruskal–Wallis tests (p ≤ 0.05).ResultsComputed tomography revealed iohexol distribution around the openings of the target foramina in all cadavers. In living dogs, HR, SAP, MAP, DAP and fR significantly increased after stimulation within each treatment (p < 0.03). Physiologic responses were significantly attenuated, but not absent, in the M-EBLOCK [HR (p = 0.019), SAP, MAP, DAP and fR (all p ≤ 0.001)] compared with those in the Control.Conclusions and clinical relevanceConcurrent injections of lidocaine at the maxillary and ethmoidal foramina attenuated HR, arterial pressure and fR responses to nasal stimulation in Beagle dogs. 相似文献