全文获取类型
收费全文 | 105854篇 |
免费 | 5451篇 |
国内免费 | 52篇 |
专业分类
林业 | 4326篇 |
农学 | 3045篇 |
基础科学 | 729篇 |
11775篇 | |
综合类 | 20731篇 |
农作物 | 4319篇 |
水产渔业 | 4646篇 |
畜牧兽医 | 54442篇 |
园艺 | 1202篇 |
植物保护 | 6142篇 |
出版年
2018年 | 1214篇 |
2017年 | 1341篇 |
2016年 | 1296篇 |
2015年 | 1095篇 |
2014年 | 1269篇 |
2013年 | 3940篇 |
2012年 | 2584篇 |
2011年 | 3213篇 |
2010年 | 2097篇 |
2009年 | 2073篇 |
2008年 | 3233篇 |
2007年 | 2959篇 |
2006年 | 2823篇 |
2005年 | 2654篇 |
2004年 | 2759篇 |
2003年 | 2695篇 |
2002年 | 2633篇 |
2001年 | 3272篇 |
2000年 | 3292篇 |
1999年 | 2441篇 |
1998年 | 1070篇 |
1997年 | 1084篇 |
1995年 | 1251篇 |
1994年 | 1165篇 |
1993年 | 1121篇 |
1992年 | 2363篇 |
1991年 | 2531篇 |
1990年 | 2440篇 |
1989年 | 2497篇 |
1988年 | 2272篇 |
1987年 | 2350篇 |
1986年 | 2484篇 |
1985年 | 2394篇 |
1984年 | 1918篇 |
1983年 | 1774篇 |
1982年 | 1166篇 |
1981年 | 1123篇 |
1980年 | 1025篇 |
1979年 | 1762篇 |
1978年 | 1424篇 |
1977年 | 1146篇 |
1976年 | 1130篇 |
1975年 | 1166篇 |
1974年 | 1524篇 |
1973年 | 1610篇 |
1972年 | 1584篇 |
1971年 | 1515篇 |
1970年 | 1408篇 |
1969年 | 1262篇 |
1967年 | 1094篇 |
排序方式: 共有10000条查询结果,搜索用时 67 毫秒
991.
992.
D.Q. Xu M. Liu Y.Z. Xiong C.Y. Deng S.W. Jiang J.L. Li B. Zuo M.G. Lei F.E. Li R. Zheng 《Livestock Science》2007,106(1):96-101
Skeletal muscle genes are potential candidates for production and meat quality. Screening a subtracted cDNA library constructed with mRNA obtained from longissimus dorsi muscles of F1 hybrids Landrace × Yorkshire and their female parents Yorkshire, we isolated two partial sequences coding for the H3-K4-specific methyltransferase (KIAA1717) and skeletal muscle myosin regulatory light chain (HUMMLC2B) genes. Database search revealed KIAA1717 and HUMMLC2B encoded proteins with SET domain and EF-hand calcium binding motif, respectively. In the present work we identified their partial polymorphisms and two SNPs, one (C1354T) at the 3′ untranslated region (UTR) of KIAA1717 and one (A345G) at the SINE (PRE-1) element of HUMMLC2B, both created/disrupted a restriction site for endonuclease Msp I. The selected pigs were genotyped at the KIAA1717 C1354T and HUMMLC2B A345G sites by means of a PCR-RFLP protocol. Significant associations were observed for the KIAA1717 C1354T polymorphic site with meat marbling (longissimus doris (p < 0.05), biceps femoris (p < 0.01)) and intramuscular fat (p < 0.01). HUMMLC2B A345G were significantly associated with meat pH (longissimus doris (p < 0.05), biceps femoris (p < 0.01)), drip loss (p < 0.01), water holding capacity (p < 0.01) and meat color value (longissimus doris (p < 0.01), biceps femoris (p < 0.05)). Further studies are needed to confirm these preliminary results. 相似文献
993.
994.
Response of healthy dogs to infusions of human serum albumin 总被引:1,自引:0,他引:1
Cohn LA Kerl ME Lenox CE Livingston RS Dodam JR 《American journal of veterinary research》2007,68(6):657-663
OBJECTIVE: To evaluate the clinical and immunologic response in healthy dogs to infusions of human serum albumin (HSA). ANIMALS: 9 healthy purpose-bred mixed-breed dogs. PROCEDURES: Each dog was administered a 25% HSA solution once or twice. Various physical examination and laboratory variables were serially evaluated. Antibody against HSA was assayed before and after infusion by use of an ELISA. Intradermal testing was also conducted. A repeated-measures ANOVA or Friedman repeated-measures ANOVA on ranks was used to compare results for the variables. RESULTS: Adverse clinical reactions were observed after the first or second infusion in 3 dogs. Anaphylactoid reactions were observed in 1 of 9 dogs during the first infusion and in 2 of 2 dogs administered a second infusion. Two dogs developed severe edema and urticaria 6 or 7 days after an initial infusion. All dogs developed anti-HSA antibodies. Positive responses for ID tests were observed in 8 of 9 dogs. Short-term increases were detected in blood protein, total bilirubin, and calcium concentrations after HSA infusion. Serum cholesterol concentrations and platelet counts decreased after HSA infusion. CONCLUSIONS AND CLINICAL RELEVANCE: Administration of HSA resulted in profound reactions in 2 of 9 dogs administered a single infusion and in 2 of 2 dogs administered a second infusion. This indicates that there is risk of life-threatening adverse reactions to HSA infusion in healthy dogs. 相似文献
995.
Terry J Klopfenstein Galen E Erickson Virgil R Bremer 《Veterinary Clinics of North America: Food Animal Practice》2007,23(2):223-45, vi
Corn milling byproducts are expected to increase dramatically in supply as the ethanol industry expands. Distillers grains, corn gluten feed, or a combination of both byproducts offer many feeding options when included in feedlot rations. These byproduct feeds may effectively improve cattle performance and operation profitability. When these byproducts are fed in feedlot diets, adjustments to grain processing method and roughage level may improve cattle performance. Innovative storage methods for wet byproducts and the use of dried byproducts offer small operations flexibility when using byproducts. As new byproducts are developed by ethanol plants, they should be evaluated with performance data to determine their product-specific feeding values. 相似文献
996.
997.
Intorre L Meucci V Di Bello D Monni G Soldani G Pretti C 《Journal of the American Veterinary Medical Association》2007,231(4):590-595
OBJECTIVE: To determine tolerance of goldfish and zebrafish to benzalkonium chloride, formalin, malachite green, and potassium permanganate. DESIGN: Tolerance study. ANIMALS: Adult goldfish (Carassius auratus) and zebrafish (Danio rerio). PROCEDURES: Groups of fish (n = 10/group) were exposed to each disinfectant at the therapeutic dosage; at 0.25, 0.5, 3, and 5 times the concentration used for the therapeutic dosage; and at the concentration used for the therapeutic dosage but for 3 or 5 times the recommended exposure time. RESULTS: In both species, exposure to malachite green at the therapeutic dosage resulted in toxic effects, including death. Exposure to formalin at the therapeutic dosage resulted in toxic effects in goldfish, but not zebrafish, and exposure to potassium permanganate resulted in toxic effects in zebrafish, but not goldfish. On the basis of the ratio of therapeutic dosage to median lethal dosage, in goldfish, formalin was more toxic than benzalkonium chloride, which was more toxic than malachite green, which was more toxic than potassium permanganate. In zebrafish, potassium permanganate was more toxic than formalin and benzalkonium chloride, which were approximately equally toxic and more toxic than malachite green. Extending treatment time increased the toxicity of potassium permanganate in zebrafish and the toxicity of formalin and malachite green in goldfish, but did not alter the toxicity of the other disinfectants. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that there was no consistency between zebrafish and goldfish in their tolerance to disinfectants, and that therapeutic dosages reported in the literature for these disinfectants were not always safe. 相似文献
998.
Banerjee P Biswas SJ Belon P Khuda-Bukhsh AR 《Journal of veterinary medicine. A, Physiology, pathology, clinical medicine》2007,54(7):370-376
Groundwater arsenic contamination has become a menacing global problem. No drug is available until now to combat chronic arsenic poisoning. To examine if a potentized homeopathic remedy, Arsenicum Album-200, can effectively combat chronic arsenic toxicity induced by repeated injections of Arsenic trioxide in mice, the following experimental design was adopted. Mice (Mus musculus) were injected subcutaneously with 0.016% arsenic trioxide at the rate of 1 ml/100 g body weight, at an interval of 7 days until they were killed at day 30, 60, 90 or 120 and were divided into three groups: (i) one receiving a daily dose of Arsenicum Album-200 through oral administration, (ii) one receiving the same dose of diluted succussed alcohol (Alcohol-200) and (iii) another receiving neither drug, nor succussed alcohol. The remedy or the placebo, as the case may be, was fed from the next day onwards after injection until the day before the next injection, and the cycle was repeated until the mice were killed. Two other control groups were also maintained: one receiving only normal diet, and the other receiving normal diet and succussed alcohol. Several toxicity assays, such as cytogenetical (chromosome aberrations, micronuclei, mitotic index, sperm head anomaly) and biochemical (acid and alkaline phosphatases, lipid peroxidation), were periodically made. Compared with controls, the drug fed mice showed reduced toxicity at statistically significant levels in respect of all the parameters studied, thereby indicating protective potentials of the homeopathic drug against chronic arsenic poisoning. 相似文献
999.
1000.
Pickworth CL Loerch SC Kopec RE Schwartz SJ Fluharty FL 《Journal of animal science》2012,90(5):1553-1561
Quantification of the pro-vitamin A carotenoids in feedstuffs commonly fed to livestock has been ignored for many years. A greater dietary concentration of vitamin A has the potential to limit adipogenesis in cattle, thereby reducing carcass quality and value. A survey of 18 feedstuffs commonly fed to beef cattle was conducted for determination of vitamin A equivalents based on analysis of carotenoids. The pro-vitamin A carotenoids of interest were β-carotene, α-carotene, and β-cryptoxanthin. Collaborators in 5 states collected the feedstuffs and then shipped them to The Ohio State University for compilation and analysis. Carotenoids were extracted from the feedstuffs and then quantified using HPLC with photodiode array analysis. Fresh fescue pasture contained approximately 10 times more vitamin A equivalents than hay and 5 times more than corn silage (39,865, 2,750, and 6,900 IU of vitamin A/kg of DM for fresh pasture, hay, and corn silage, respectively). Beta-cryptoxanthin and α-carotene could not be detected in any forage samples. Hay and corn silage vitamin A equivalents decreased over extended periods of time from harvest to sample collection. Corn was the only feedstuff to have appreciable concentrations of all 3 pro-vitamin A carotenoids quantified. Corn processing had a minimal impact on the vitamin A equivalents. High-moisture corn contained 54% more vitamin A equivalents than whole shelled corn (378 and 174 IU of vitamin A/kg of DM, respectively). Pro-vitamin A carotenoids were more concentrated in corn coproducts than in whole shelled corn. The drying of distillers grains with solubles may significantly degrade β-carotene (800 and 480 IU/kg of DM for wet and dry distillers grains, respectively). Soybean-based feedstuffs contain a small concentration of pro-vitamin A carotenoids, at 55 and 45 IU of vitamin A/kg of DM for soybean meal and soybean hulls, respectively. Overall, there was considerable variation in the pro-vitamin A content of feedstuffs based on location and storage conditions. An extensive analysis of feedstuffs would need to be conducted for an accurate estimation of the vitamin A content of feedlot cattle diets. 相似文献