全文获取类型
收费全文 | 22552篇 |
免费 | 219篇 |
国内免费 | 129篇 |
专业分类
林业 | 906篇 |
农学 | 236篇 |
基础科学 | 80篇 |
3205篇 | |
综合类 | 4580篇 |
农作物 | 798篇 |
水产渔业 | 221篇 |
畜牧兽医 | 12031篇 |
园艺 | 138篇 |
植物保护 | 705篇 |
出版年
2018年 | 29篇 |
2016年 | 30篇 |
2015年 | 45篇 |
2014年 | 74篇 |
2013年 | 50篇 |
2012年 | 2095篇 |
2011年 | 2420篇 |
2010年 | 472篇 |
2009年 | 317篇 |
2008年 | 1875篇 |
2007年 | 1949篇 |
2006年 | 1746篇 |
2005年 | 1648篇 |
2004年 | 1600篇 |
2003年 | 1442篇 |
2002年 | 1288篇 |
2001年 | 886篇 |
2000年 | 1095篇 |
1999年 | 459篇 |
1998年 | 71篇 |
1997年 | 81篇 |
1996年 | 73篇 |
1995年 | 103篇 |
1994年 | 123篇 |
1993年 | 162篇 |
1992年 | 171篇 |
1991年 | 150篇 |
1990年 | 148篇 |
1989年 | 116篇 |
1988年 | 148篇 |
1987年 | 139篇 |
1986年 | 104篇 |
1985年 | 121篇 |
1984年 | 135篇 |
1983年 | 122篇 |
1982年 | 109篇 |
1981年 | 73篇 |
1980年 | 51篇 |
1979年 | 44篇 |
1978年 | 37篇 |
1975年 | 36篇 |
1974年 | 50篇 |
1973年 | 46篇 |
1972年 | 51篇 |
1967年 | 35篇 |
1963年 | 35篇 |
1959年 | 28篇 |
1958年 | 32篇 |
1955年 | 27篇 |
1953年 | 28篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
1. An experiment was conducted to study the effect of thiram on liver antioxidant capacity and incidence of tibial dyschondroplasia in broilers. 2. One hundred and twenty Avian commercial broilers were allotted at random to three treatments: control group, low thiram group (50 mg/kg) and high thiram group (100 mg/kg). 3. Blood samples were collected to determine the activity of AST (aspartate aminotransferase). At the end of the trial, broilers were killed and liver samples were collected to determine the activity of SOD (superoxide dismutase), GSH-Px (glutathione peroxidase) and MDA (malondialdehyde) content, while the right proximal tibiotarsi were dissected in longitudinal section for assessment of tibial dyschondroplasia (TD) incidence and TD score. 4. The results showed that thiram increased the incidence of TD and TD scores, increased serum AST activity and MDA content of liver, and decreased the activity of SOD and GSH-Px in the liver. 5. They suggest that thiram causes TD in broilers by reducing liver antioxidation capability and damaging liver function; this may be one of the mechanisms by which thiram causes TD in broilers. 相似文献
112.
Barbut S 《British poultry science》2007,48(6):655-660
1. The effects of 2% whole milk proteins, milk protein's two major components (caseinate and whey) and some of their fractions (beta-lactoglobulin and two hydrolysed whey proteins) were evaluated in a frankfurter-type product made from mechanically deboned chicken meat. 2. Adding caseinate, regular whey protein and the two whey protein hydrolysates (WPH-I and II) significantly reduced cooking loss compared to the control; lowest reduction was obtained with the two hydrolysates. 3. Caseinate and regular whey increased hardness, but WPH-I and II substantially reduced hardness, fracturability and springiness. 4. The more hydrolysed whey (8.5% vs 5.2%; WPH-II vs WPH-I, respectively) caused a greater disruption to texture, which could be explained by the light micrographs showing an interference with meat protein binding. 5. The most cost-effective ingredient tested here was the caseinate. 相似文献
113.
Clinical and in vitro efficacy of amoxicillin against bacteria associated with feline skin wounds and abscesses 总被引:1,自引:0,他引:1
Roy J Messier S Labrecque O Cox WR 《The Canadian veterinary journal. La revue veterinaire canadienne》2007,48(6):607-611
A clinical trial involving 122 cats with infected skin wounds or abscesses presented to 10 veterinary clinics was conducted to evaluate the efficacy of 2 oral amoxicillin drug products (a paste and a suspension). A 2nd objective of the study was to identify bacteria involved in such infections and verify their in vitro sensitivity to amoxicillin. Samples of wound exudate were harvested at the time of presentation and submitted for aerobic and anaerobic culture. The sensitivity to amoxicillin of isolates thought to be infecting agents was tested, using a standard minimum inhibitory concentration method. Pasteuralla multocida and obligate anaerobes of the genera Prevotella, Fusobacterium, and Porphyromonas were the most frequently isolated pathogens. Overall, their in vitro susceptibility to amoxicillin was very good. Both drug products were clinically efficacious with a global success rate of 95.1% for cats administered oral amoxicillin at 11-22 mg/kg bodyweight (mean 13.8 mg/kg bodyweight) twice daily for 7 to 10 days. 相似文献
114.
Relave F Lefebvre RC Beaudoin S Price C 《The Canadian veterinary journal. La revue veterinaire canadienne》2007,48(8):823-826
The aim of this study was to validate an enzyme-linked immunosorbent assay (ELISA) for the measurement of progesterone (P4) in mares. Specifically, the objectives were as follows: (1) to determine the specificity and sensitivity of the ELISA test for determination of P4, (2) to measure the potential agreement between the 2 people performing the test, and 3) to evaluate the effect of time on the outcome. Ten mares were sampled on the day before ovulation (D-1), and on days 1 (D1), 3 (D3), and 5 (D5) following ovulation, during the reproductive season. While mares were cycling regularly, estrus was induced by the injection of 5 mg of prostaglandin (PGF2) and monitored starting on the 4th day by daily transrectal palpation and ultrasonography to determine the time of ovulation. Blood was collected and all samples (n=96) were assayed for P4 by a semiquantitative ELISA, by chemiluminescent immunoassay, and by radioimmunoassay (RIA). Based on the RIA, values of P4 on D-1, D1, D3, and D5 were significantly different (P < 0.0001) with mean and standard deviation(s) of 0.004, s = 0.52; 2.05, s = 2.58; 8.37, s = 4.17; and 12.76, s = 4.00 ng/mL respectively. The sensitivity and specificity of the semiquantitative assay were 94% and 95%, respectively for the lowest values of P4 (< 1.0 ng/mL). The value of kappa was 0.90 between 2 individuals performing the test. In conclusion, these results suggest that the semiquantitative test may be used reliably and economically to evaluate P4 levels in equine plasma in the clinical 相似文献
115.
1. Regulation of meat taste is one effective method for improvement of meat quality. In this study, effects of dietary leucine (Leu) content on taste-active components, especially free glutamate (Glu), in meat were investigated. 2. Broiler chickens (28 d old) were fed on diets with graded dietary Leu content (100, 130 or 150% of Leu requirement in NRC, 1994) for 10 d before marketing. Taste-active components of meat (free amino acids and ATP metabolites) and sensory score of meat soup were estimated. 3. Free Glu content, the main taste-active component of meat, was significantly increased by dietary Leu. Compared with the Leu 130% group, free Glu was increased by 17% in the Leu 100% group. Free Glu of meat tended to decrease in the Leu 150% group. In contrast, inosine monophosphate content in meat did not change among all groups. 4. Sensory evaluation of meat soup from the Leu 100 and 150% groups showed that they had different meat tastes. Sensory scores of overall preference, umami taste and chicken-like taste were significantly higher in the Leu 100% group. 5. These results suggest that dietary Leu content is a regulating factor of free Glu in meat. Decreasing dietary Leu induces an increase in the free Glu content of meat and improves meat taste. 相似文献
116.
Schiavone A Chiarini R Marzoni M Castillo A Tassone S Romboli I 《British poultry science》2007,48(5):573-579
1. A trial was conducted in order to increase the docosahexaenoic acid (DHA) content in the meat of Muscovy ducks (Cairina moschata domestica L.) fed on a diet supplemented with the microalga Crypthecodinium cohnii. 2. Two diets were provided to 48 male and 48 female ducks, belonging to an Italian rural strain during the last 3 weeks of life: a maize-soybean based diet as the control diet and the same diet supplemented with 5 g/kg microalga meal. 3. Dietary treatment did not induce differences in growth performances and slaughter traits. Similarly, chemical composition, colour, pH, oxidative stability and sensory characteristics of breast muscle were not influenced by the diet. 4. A significant increase of DHA content in breast meat of ducks fed on the Crypthecodinium cohnii enriched diet was observed. 相似文献
117.
118.
Ohlschläger S Spolders M Meyer U Flachowsky G 《Berliner und Münchener tier?rztliche Wochenschrift》2007,120(5-6):226-231
At the Institute of Animal Nutrition of the Federal Agricultural Research Centre (FAL) in Braunschweig a feeding trial with 30 first lactating cows (German Holstein) was realised in 2004 for a complete lactation. All animals received a diet based on maize- and grass-silage ad libitum at the rate of 60:40 (DM-base) and concentrate depending on their milk yield.The animals were fed with energy and protein as recommended (GfE 2001) and were kept in loose housing. After calving they were split randomly into two feeding groups with 15 animals each. Group 1 was fed a concentrate according to the recommendations of the GfE (2001), whereas group 2 was offered the same concentrate with roughly the double amount of calcium, magnesium, phosphorus, copper, zinc, beta-carotene and vitamins A and E. To study the influence of the different concentrates on the serum concentrations of minerals and vitamins, blood, feed and milk samples were regularly taken and analysed in the course of lactation. Significantly higher blood concentrations were detected for phosphorus, zinc and vitamin E in group 2, but therefore a direct influence of the feeding on the blood concentrations was detected only for zinc and vitamin E. Over the whole lactation the average milk yield of group 1 was 2.6 kg/day higher and the average milk fat content was reduced about 0.6 percent points compared to group 2. 相似文献
119.
Grobbel M Lübke-Becker A Alesík E Schwarz S Wallmann J Werckenthin C Wieler LH 《Berliner und Münchener tier?rztliche Wochenschrift》2007,120(9-10):391-401
A total of 417 isolates of Escherichia coli collected from five animal species/organ system combinations from swine [urinary/genital tract (UGT) incl. mastitis metritis agalactia syndrome], horses [genital tract (GT)] and dogs/cats [respiratory tract (RT), UGT and gastrointestinal tract (GIT)] were analysed quantitatively for their susceptibility against different antimicrobial agents by determination of minimum inhibitory concentrations. Regardless of which animal species the strains originated from, resistance appeared most frequently against sulfamethoxazole (18-59%), tetracycline (14-54 %), and ampicillin (14-39%). High percentages of intermediate isolates were observed for cephalothin (39-46 %). In general, low prevalences of resistance were detected for amoxicillin/clavulanic acid (1-4%), gentamicin (1-9%), and cefazolin (0-11%). Generally speaking, the antimicrobial resistance situation among E. coli isolates from horses and small animals is relatively good. 相似文献
120.
Schwarz S Alesík E Grobbel M Lübke-Becker A Werckenthin C Wieler LH Wallmann J 《Berliner und Münchener tier?rztliche Wochenschrift》2007,120(9-10):423-430
A total of 92 canine/feline Pasteurella multocida strains form respiratory tract infections or infections of skin/ear/mouth as well as 42 canine/feline Bordetella bronchiseptica strains from respiratory tract infections were investigated for their susceptibility to antimicrobial agents. While the P. multocida strains were susceptible to all antimicrobial agents tested - except sulfonamides -, a considerable number of the B. bronchiseptica strains was resistant or exhibited high MIC values against a number of antimicrobial agents including penicillin G, oxacillin, cefazolin, ceftiofur, cefquinome, sulfamethoxazole, and trimethoprim/sulfamethoxazole. 相似文献