全文获取类型
收费全文 | 870篇 |
免费 | 44篇 |
国内免费 | 2篇 |
专业分类
林业 | 24篇 |
农学 | 10篇 |
基础科学 | 8篇 |
106篇 | |
综合类 | 216篇 |
农作物 | 50篇 |
水产渔业 | 25篇 |
畜牧兽医 | 403篇 |
园艺 | 21篇 |
植物保护 | 53篇 |
出版年
2021年 | 9篇 |
2018年 | 8篇 |
2017年 | 10篇 |
2016年 | 15篇 |
2015年 | 15篇 |
2014年 | 12篇 |
2013年 | 39篇 |
2012年 | 25篇 |
2011年 | 28篇 |
2010年 | 27篇 |
2009年 | 19篇 |
2008年 | 40篇 |
2007年 | 21篇 |
2006年 | 30篇 |
2005年 | 37篇 |
2004年 | 39篇 |
2003年 | 34篇 |
2002年 | 51篇 |
2001年 | 15篇 |
2000年 | 14篇 |
1999年 | 20篇 |
1998年 | 13篇 |
1995年 | 6篇 |
1992年 | 15篇 |
1991年 | 17篇 |
1990年 | 9篇 |
1989年 | 17篇 |
1988年 | 13篇 |
1987年 | 18篇 |
1986年 | 12篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1983年 | 11篇 |
1982年 | 9篇 |
1981年 | 6篇 |
1979年 | 9篇 |
1977年 | 9篇 |
1976年 | 7篇 |
1975年 | 8篇 |
1974年 | 10篇 |
1973年 | 14篇 |
1972年 | 7篇 |
1971年 | 9篇 |
1970年 | 8篇 |
1969年 | 9篇 |
1968年 | 6篇 |
1967年 | 8篇 |
1918年 | 5篇 |
1915年 | 7篇 |
1914年 | 5篇 |
排序方式: 共有916条查询结果,搜索用时 31 毫秒
31.
32.
Cohen ND Berry SM Peloso JG Mundy GD Howard IC 《Journal of the American Veterinary Medical Association》2000,216(8):1273-1278
OBJECTIVE: To determine the association between high-speed exercise and risk of injury while racing among Thoroughbreds in Kentucky. DESIGN: Matched case-control study. ANIMALS: 206 Thoroughbreds that sustained a musculoskeletal injury while racing and 412 Thoroughbreds that were not injured during the same races. PROCEDURE: Data regarding official timed workouts and races and the Beyer's numbers for the 3 races before the race during which injury occurred were extracted from past performance charts and compared between injured horses and control horses. RESULTS: For injured horses, cumulative distance of high-speed exercise during the 1- and 2-month periods prior to the race in which injury occurred was significantly less than that of control horses; for either period, a difference of 10 furlongs was associated with approximately 2-fold greater risk of injury. Beyer's numbers were significantly higher for injured horses than for control horses. These effects remained significant after adjusting for age and results of prerace physical inspection. CONCLUSIONS AND CLINICAL RELEVANCE: In Kentucky, injured horses had significantly less cumulative high-speed exercise than did control horses during the 1- and 2-month periods prior to the race in which injury occurred. These results differ from those observed in California. The association of injury with cumulative high-speed exercise appears to vary among regions in the United States. 相似文献
33.
Smith KE Wall R Howard JJ Strong L Marchiondo AA Jeannin P 《Veterinary parasitology》2000,88(3-4):261-268
The insecticidal effects of the phenylpyrazole, fipronil, and a pyrethroid, beta-cyfluthrin, on larvae of the blowfly Lucilia sericata were determined in laboratory assays. When first stage larvae of L. sericata were reared on homogenized pig liver which had been treated with known amounts of test compounds, both fipronil and beta-cyfluthrin induced significant levels of mortality compared to acetone and water controls. However, fipronil was approximately 10 times more toxic than beta-cyfluthrin to L. sericata larvae following ingestion. Beta-cyfluthrin had little effect on mortality until concentrations of approximately 0.5 ppm were reached. In contrast, fipronil effected L. sericata mortality at a concentration of 0.05 ppm and 100% mortality was reached by 0.5 ppm. The lethal concentration (LC50) value for beta-cyfluthrin was 1.56 ppm as compared to 0.14 ppm for fipronil. Following contact of first and third stage larvae with cloth impregnated with known amounts of test compound, the mortality profiles of fipronil and beta-cyfluthrin were similar. At short contact times, the LC50 values for fipronil were lower than those for beta-cyfluthrin. However, at the highest contact time evaluated for the first stage larvae, 300 s, there was a reversal in this trend. The results suggest that the phenylpyrazole fipronil may represent a new potential insecticide for development against blowfly strike of sheep. 相似文献
34.
35.
Assays of [14C]leucine incorporation were used to measure effects of herbicides on suspensioncultured heterotrophic Solanum nigrum cells. Most herbicidal vs. nonherbicidal chemicals in a set of 47 compounds could be distinguished from each other based on their extent of inhibition of leucine incorporation by S. nigrum cells. Herbicides which failed to inhibit leucine incorporation were photosynthetic inhibitors. Both phytotoxic and nonphytotoxic thiocarbamate analogs (as determined by whole-plant studies) tended to inhibit leucine incorporation. It was concluded that the leucine incorporation screen could detect a majority of compounds tested which are herbicidal, and that it may also be useful to detect compounds which have cellular toxicity which is not observed in the whole plant. 相似文献
36.
E. Combs T. Beachler J. R. Troy A. Olds-Sanchez J. M. Howard A. Fales-Williams M. Yaeger D. M. Tatarniuk 《Equine Veterinary Education》2022,34(8):e318-e322
A 15-year-old Paint mare (Case 1) and a 15-year-old Arabian mare (Case 2) were presented for aggressive and undesired behaviour. Reproductive evaluation revealed, initially, an enlarged ovary with a smaller/normal sized contralateral ovary in each case. Granulosa cell tumour (GCT) panel testing revealed elevated inhibin B in both cases and elevated anti-Mullerian hormone (AMH) levels only in Case 1 determined from currently established reference ranges. Based on a presumptive diagnosis of GCT, bilateral standing ovariectomy was elected for both mares. In each case neoplastic tissue consistent with luteoma was detected only on histological examination in the smaller/normal sized left ovary; the right ovary appearing normal. Long-term follow-up was performed 1 year and 5 years post-operatively by telephone. The owners were satisfied with the outcome and each patient demonstrated resolution of aggressive stallion-like behaviour. Each case returned to the owners' intended use. In conclusion, luteoma should be considered as a differential diagnosis for ovarian neoplasms in horses related to behavioural abnormalities, even in normal-sized ovaries. 相似文献
37.
Cryopreservation of Piau‐Breed Wild Boar Sperm: Assessment of Cooling Curves and Centrifugation Regimes
下载免费PDF全文
![点击此处可从《Reproduction in domestic animals》网站下载免费的PDF全文](/ch/ext_images/free.gif)
HH Shiomi RO Pinho DMA Lima JB Siqueira MCR Santos EV Costa PS Lopes SEF Guimarães JD Guimarães 《Reproduction in domestic animals》2015,50(4):545-553
This study aimed to assess the effects of different cooling curves and centrifugation regimes used in cryopreservation protocols on the post‐thaw viability of Piau‐breed wild boar (Sus scrofa) sperm using in vitro assessment tests. Two centrifugations (800 g for 10 min and 2400 g for 3 min) and two cooling curves (conventional cooling using nitrogen vapour – freezing 1 and automated cooling using a programmed freezing machine – freezing 2) were tested. Therefore, the treatments were divided into M3 – centrifugation at 2400 g for 3 min and freezing 2; M10 – centrifugation at 800 g for 10 min and freezing 2; R3 – centrifugation at 2400 g for 3 min and freezing 1; and R10 – centrifugation at 800 g for 10 min and freezing 1. No significant differences (p > 0.05) between treatments occurred post‐thawing regarding the total sperm motility means recorded. The mean values of the different treatments were not different from each other regarding the supravital staining (SV), hypo‐osmotic test (HO), sperm–egg binding assay or sperm morphology. This study showed that both the cooling curve and the centrifugation regime affected the quality of post‐thaw sperm, and centrifugation for shorter times and cooling curves using automated cooling are the most suitable for minimizing sperm injury. 相似文献
38.
Cheng Xiaoqin Ping Tain Li Zuzheng Wang Tian Han Hairong Epstein Howard E. 《New Forests》2022,53(1):125-142
New Forests - Plant functional traits have been shown to vary with environmental conditions. However, we lack empirical data on how plant functional traits of different plant life forms respond to... 相似文献
39.
Thomas P. Howard Brendan Fahy Fiona Leigh Phil Howell Wayne Powell Andy Greenland Kay Trafford Alison M. Smith 《Journal of Cereal Science》2014
The effects on barley starch and grain properties of four starch synthesis mutations were studied during the introgression of the mutations from diverse backgrounds into an elite variety. The lys5f (ADPglucose transporter), wax (granule-bound starch synthase), isa1 (debranching enzyme isoamylase 1) and sex6 (starch synthase IIa) mutations were introgressed into NFC Tipple to give mutant and wild-type BC2F4 families with different genomic contributions of the donor parent. Comparison of starch and grain properties between the donor parents, the BC2F4 families and NFC Tipple allowed the effects of the mutations to be distinguished from genetic background effects. The wax and sex6 mutations had marked effects on starch properties regardless of genetic background. The sex6 mutation conditioned low grain weight and starch content, but the wax mutation did not. The lys5 mutation conditioned low grain weight and starch content, but exceptionally high β-glucan contents. The isa1 mutation promotes synthesis of soluble α-glucan (phytoglycogen). Its introgression into NFC Tipple increased grain weight and total α-glucan content relative to the donor parent, but reduced the ratio of phytoglycogen to starch. This study shows that introgression of mutations into a common, commercial background provides new insights that could not be gained from the donor parent. 相似文献
40.
Steffen S. Madsen Stephen D. McCormick Graham Young Jeanette S. Endersen Richard S. Nishioka Howard A. Bern 《Fish physiology and biochemistry》1994,13(1):1-11
Several experiments were performed to investigate the physiology of seawater acclimation in the striped bass, Morone saxatilis. Transfer of fish from fresh water (FW) to seawater (SW; 31–32 ppt) induced only a minimal disturbance of osmotic homeostasis.
Ambient salinity did not affect plasma thyroxine, but plasma cortisol remained elevated for 24h after SW transfer. Gill and
opercular membrane chloride cell density and Na+,K+-ATPase activity were relatively high and unaffected by salinity. Average chloride cell size, however, was slightly increased
(16%) in SW-acclimated fish. Gill succinate dehydrogenase activity was higher in SW-acclimated fish than in FW fish. Kidney
Na+, K+-ATPase activity was slightly lower (16%) in SW fish than in FW fish. Posterior intestinal Na+,K+-ATPase activity and water transport capacity (Jv) did not change upon SW transfer, whereas middle intestinal Na+,K+-ATPase activity increased 35% after transfer and was correlated with an increase in Jv (110%). As salinity induced only minor changes in the osmoregulatory organs examined, it is proposed that the intrinsic euryhalinity
of the striped bass may be related to a high degree of “preparedness” for hypoosmoregulation that is uncommon among teleosts
studied to data. 相似文献