全文获取类型
收费全文 | 343篇 |
免费 | 7篇 |
国内免费 | 2篇 |
专业分类
林业 | 17篇 |
农学 | 11篇 |
基础科学 | 1篇 |
105篇 | |
综合类 | 11篇 |
农作物 | 7篇 |
水产渔业 | 5篇 |
畜牧兽医 | 171篇 |
园艺 | 1篇 |
植物保护 | 23篇 |
出版年
2023年 | 1篇 |
2022年 | 9篇 |
2021年 | 21篇 |
2020年 | 12篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2017年 | 3篇 |
2016年 | 8篇 |
2015年 | 20篇 |
2014年 | 27篇 |
2013年 | 28篇 |
2012年 | 15篇 |
2011年 | 24篇 |
2010年 | 14篇 |
2009年 | 13篇 |
2008年 | 20篇 |
2007年 | 26篇 |
2006年 | 23篇 |
2005年 | 27篇 |
2004年 | 12篇 |
2003年 | 12篇 |
2002年 | 11篇 |
2001年 | 6篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1977年 | 1篇 |
排序方式: 共有352条查询结果,搜索用时 171 毫秒
341.
342.
343.
344.
Rika Fukumori Rina Ikeno Kenichi Izumi Kazuya Doi Marina Otsuka Kazuyuki Suzuki Shin Oikawa 《Animal Science Journal》2021,92(1):e13673
The objective of this study was to evaluate effects of sodium-butyrate supplementation on gastrointestinal function and the inflammatory response to ruminal acidosis (RA) challenge in cows. Four nonlactating cows with a rumen cannula were assigned to two treatments in a crossover design. Treatments were ruminal administration of sodium-butyrate (BUT) or control (CON). Sodium-butyrate was provided as Gustor BP70 and administered at a butyrate dose of 0.04% per kg body weight. The CON premix was made by replacing sodium-butyrate with wheat bran. Experimental periods were 28 days long with 21-day washout period separating the treatments. On Day 25 of each period, corn starch was ruminally administered at 0.7% per kg body weight as RA challenge. After RA challenge, ruminal pH was lower, and endotoxin concentration was higher for cows provided with BUT than those with CON, but the increase in fecal starch and the decrease in fecal pH were attenuated by BUT. The effect of butyrate supplementation on serum lipopolysaccharide-binding protein after RA challenge was not found. From these findings, butyrate supplementation mitigated rectal acidosis by reducing the flux of fermentable carbohydrate into the large intestine. An anti-inflammatory effect of butyrate was not observed, possibly due to lower pH and higher endotoxin concentration in the rumen. 相似文献
345.
Teruo ITOH Atsuko KOJIMOTO Kazuyuki UCHIDA James K. CHAMBERS Hiroki SHII 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2021,83(2):230
We evaluated the postsurgical outcomes of cutaneous or subcutaneous mast cell tumors (MCTs, n=25) in 23 dogs, resected with lateral surgical margins proportional to the widest tumor diameter, including at least one facial plane. The tumor diameter range was 0.3–2.6 cm (median: 0.9 cm), and all were histologically diagnosed as Kiupel’s low-grade MCT. Resection was histologically complete in 20, close (deep margin) in three, and incomplete (deep margin) in two. No dogs developed local recurrence at the site of initial surgery during follow-up of 161–2,219 days (median: 976 days). These results suggest that resection of low-grade, relatively small MCTs with surgical margins proportional to the tumor diameter is a practical procedure with high success rates. 相似文献
346.
We investigated clonal and site variations in wood fiber length, microfibril angle, and specific gravity of seven natural
hybrid clones of Acacia (Acacia mangium × Acacia auriculiformis) grown in northern and southern Vietnam. Fiber length did not differ between clones or between sites. The microfibril angle
of the S2 layer did not significantly differ between clones but significantly differed between sites. Clone and site significantly
affected specific gravity. The significant effects of genetic × environmental interactions on wood properties indicated the
difference in the response of clones to different growing conditions. The trends of changes in fiber length, microfibril angle,
and specific gravity from the vicinity of the pith to near the bark were similar for all clones at each site; however, variations
in fiber length, microfibril angle, and specific gravity were more visible in northern Vietnam than in southern Vietnam, with
a significant effect of genetic factors. This difference may be attributable to winter, which is experienced in northern Vietnam
but not in southern Vietnam. For clone selection for plantation in the northern region, combining growth rate with wood properties
was recommended. On the other hand, for plantation in the southern region, clone selection depends mainly on the growth rate,
taking into consideration the specific gravity. 相似文献
347.
Junji Matsumura Yoko Yamasaki Kazuyuki Oda Yoshitake Fujisawa 《Journal of Wood Science》2005,51(4):328-333
Nine trees of Cryptomeria japonica from six elite tree clones with a broad range of heartwood colors were selected. The profiles of pit aspiration percentage (ASP) of earlywood and latewood from pith to bark for green and air-dry conditions were determined to study the relationship between heartwood color and pit aspiration. Confocal laser scanning microscopy (CLSM) observations showed that the ASP of earlywood was low in sapwood and high in heartwood in the green condition. Pit aspiration increased in intermediate wood when compared with sapwood. On the other hand, latewood pits did not aspirate during heartwood formation. Comparing the air-dry condition with the green condition, sapwood pits aspirated during drying in both earlywood and latewood; however, there was no significant difference in pit aspiration of heartwood. There was no significant difference between samples with red and black heartwoods for ASP. The difference in ASP between individual trees was larger than that by heartwood color. The general advantage of CLSM over light microscopy is that serial optical sections along the Z axis can be obtained for any moisture condition, without the need for thin sectioning or embedding. 相似文献
348.
Lack of exposed ice inside lunar south pole Shackleton Crater 总被引:2,自引:0,他引:2
Haruyama J Ohtake M Matsunaga T Morota T Honda C Yokota Y Pieters CM Hara S Hioki K Saiki K Miyamoto H Iwasaki A Abe M Ogawa Y Takeda H Shirao M Yamaji A Josset JL 《Science (New York, N.Y.)》2008,322(5903):938-939
The inside of Shackleton Crater at the lunar south pole is permanently shadowed; it has been inferred to hold water-ice deposits. The Terrain Camera (TC), a 10-meter-resolution stereo camera onboard the Selenological and Engineering Explorer (SELENE) spacecraft, succeeded in imaging the inside of the crater, which was faintly lit by sunlight scattered from the upper inner wall near the rim. The estimated temperature of the crater floor, based on the crater shape model derived from the TC data, is less than approximately 90 kelvin, cold enough to hold water-ice. However, at the TC's spatial resolution, the derived albedo indicates that exposed relatively pure water-ice deposits are not on the crater floor. Water-ice may be disseminated and mixed with soil over a small percentage of the area or may not exist at all. 相似文献
349.
The nature of the first generation of stars in the universe remains largely unknown. Observations imply the existence of massive primordial stars early in the history of the universe, and the standard theory for the growth of cosmic structure predicts that structures grow hierarchically through gravitational instability. We have developed an ab initio computer simulation of the formation of primordial stars that follows the relevant atomic and molecular processes in a primordial gas in an expanding universe. The results show that primeval density fluctuations left over from the Big Bang can drive the formation of a tiny protostar with a mass 1% that of the Sun. The protostar is a seed for the subsequent formation of a massive primordial star. 相似文献
350.
Akinori Yamamoto Hiroko Akiyama Takuji Naokawa Yasuhiro Miyazaki Yusuke Honda Yukimasa Sano Yasuhiro Nakajima Kazuyuki Yagi 《Biology and Fertility of Soils》2014,50(1):53-62
Lime-N (calcium cyanamide, CaCN2) acts as both fertilizer and pesticide. Lime-N may reduce nitrous oxide (N2O) emission from soil, although its effectiveness and the relative mechanisms are not well understood. The aim of the study was to quantify the effect of lime-N on N2O emission from the acidic soil of tea fields. The study design consisted of two treatments: conventional fertilizer (CF) (application of conventional organo-chemical fertilizer) and lime-N (LN) (application of approximately 53 % of the applied N as lime-N and the remaining as conventional organo-chemical fertilizer). Both treatments had the same amount of N, P2O5, and K2O applied to soil between plant canopies; fertilizer was incorporated into soil. We measured N2O emissions and environmental and microbial parameters of soil between plant canopies and under the canopy of tea plants, including the concentrations of dicyandiamide and cyanamide derived from lime-N. Nitrous oxide emission from soil between plant canopies was lower in the LN treatment than in the CF treatment, and soil ammonium oxidation activity and soil denitrification rate decreased after lime-N application. We applied the acetylene inhibition technique and analyzed isotopomer ratios of N2O; the results of both techniques suggested that denitrification was the major process of N2O production in the soil between plant canopies, despite relatively low water-filled pore space. Cumulative N2O emission over the 366 days of the experiment was 36.0 % lower in the LN treatment than in the CF treatment (P?<?0.05). Our results suggest that lime-N application decreases N2O emission by inhibiting both nitrification and denitrification processes in the acidic soil. 相似文献