全文获取类型
收费全文 | 3324篇 |
免费 | 209篇 |
国内免费 | 408篇 |
专业分类
林业 | 146篇 |
农学 | 75篇 |
基础科学 | 5篇 |
47篇 | |
综合类 | 808篇 |
农作物 | 17篇 |
水产渔业 | 519篇 |
畜牧兽医 | 2239篇 |
园艺 | 46篇 |
植物保护 | 39篇 |
出版年
2024年 | 8篇 |
2023年 | 25篇 |
2022年 | 57篇 |
2021年 | 98篇 |
2020年 | 100篇 |
2019年 | 115篇 |
2018年 | 69篇 |
2017年 | 88篇 |
2016年 | 133篇 |
2015年 | 125篇 |
2014年 | 179篇 |
2013年 | 155篇 |
2012年 | 236篇 |
2011年 | 244篇 |
2010年 | 174篇 |
2009年 | 217篇 |
2008年 | 204篇 |
2007年 | 267篇 |
2006年 | 234篇 |
2005年 | 207篇 |
2004年 | 168篇 |
2003年 | 123篇 |
2002年 | 118篇 |
2001年 | 115篇 |
2000年 | 92篇 |
1999年 | 55篇 |
1998年 | 45篇 |
1997年 | 62篇 |
1996年 | 32篇 |
1995年 | 33篇 |
1994年 | 32篇 |
1993年 | 23篇 |
1992年 | 30篇 |
1991年 | 19篇 |
1990年 | 14篇 |
1989年 | 14篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 7篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1956年 | 3篇 |
排序方式: 共有3941条查询结果,搜索用时 195 毫秒
991.
Hideki OHSAKI Atsuko TANAKA Shogo HOASHI Shinji SASAZAKI Kenji OYAMA Masaaki TANIGUCHI Fumio MUKAI Hideyuki MANNEN 《Animal Science Journal》2009,80(3):225-232
Fatty acid composition of beef adipose tissue is one of important traits because high proportions of monounsaturated fatty acid are related to favorable beef flavor and tenderness. In this study, we investigated effects of genetic factors such as stearoyl-CoA desaturase (SCD) and sterol regulatory element binding protein (SREBP) on beef carcass traits including fatty acid composition using two cattle populations. Sire effect was significantly related to almost all traits except BMS, suggesting that the trait examined in this study is highly controlled by genetic factors. The effect of SCD genotype on fatty acid composition was detected remarkably in both cattle groups, especially on stearic and oleic acids. This result was consistent with our previous studies and suggests that SCD is associated with fatty acid composition. Unlike SCD genotyping, the effect of SREBP genotype was not identified in this study. Our results suggested that SCD genotype would contribute to improving beef quality in field populations. Further studies about the relationship among these factors will bring an insight into the molecular mechanism of fatty acid metabolism in cattle. 相似文献
992.
Tawadchai SUPPADIT Sanchai JATURASITHA Wirote SELASAT Rakkeart NORKEAW Pukkapong POUNGSUK Nakarin PRIPWAI 《Animal Science Journal》2009,80(3):310-315
The experiment was conducted to study the effectiveness of dried milky sludge (DMS) as a feed source for laying Japanese quails. The DMS was incorporated into the experimental diets at levels of 0, 5.0, 10.0, 15.0 and 20.0%. Four hundred quails were used in a completely randomized design. The results revealed that the daily egg-laying rate, feed cost/100 egg weight, egg width, egg length, egg weight, shell quality characteristics in terms of breaking time, Young's modulus, work, max force, fracturability, breaking stress, stiffness and power, as well as color intensity and yolk height improved significantly with increasing levels of DMS in the diet ( P < 0.05), while feed intake/bird/day, mortality and eggshell thickness showed no significant differences ( P > 0.05). From this experiment, it was found that DMS incorporated into the experimental diet at the 20.0% level yielded the most productive performance and best egg quality. 相似文献
993.
Volumes of official data sets have been increasing rapidly in the genetic evaluation using the Japanese Black routine carcass field data. Therefore, an alternative approach with smaller memory requirement to the current one using the restricted maximum likelihood (REML) and the empirical best linear unbiased prediction (EBLUP) is desired. This study applied a Bayesian analysis using Gibbs sampling (GS) to a large data set of the routine carcass field data and practically verified its validity in the estimation of breeding values. A Bayesian analysis like REML‐EBLUP was implemented, and the posterior means were calculated using every 10th sample from 90 000 of samples after 10 000 samples discarded. Moment and rank correlations between breeding values estimated by GS and REML‐EBLUP were very close to one, and the linear regression coefficients and the intercepts of the GS on the REML‐EBLUP estimates were substantially one and zero, respectively, showing a very good agreement between breeding value estimation by the current GS and the REML‐EBLUP. The current GS required only one‐sixth of the memory space with REML‐EBLUP. It is confirmed that the current GS approach with relatively small memory requirement is valid as a genetic evaluation procedure using large routine carcass data. 相似文献
994.
用新城疫病毒La Sota株作为复合物疫苗抗原,与新城疫特异性中和抗体混匀配制成4种不同比例的复合物疫苗,用1日龄普通雏鸡进行免疫效果对比试验。试验1~4组分别为免疫复合物疫苗1~4,试验5组免疫常规新城疫活苗,试验6组为空白对照组。免疫后3周采血测定HI抗体效价,同时用新城疫强毒北京株F48E9攻击。试验结果显示,试验1~6组HI抗体效价分别为3.2log2、3.1log2、3.3log2、3.2log2、3.1log2、2.9log2;攻毒后,试验1~6组鸡的死亡率分别为15%、20%、0%、35%、30%、50%。因此,新城疫病毒La Sota株与新城疫特异性抗体制备成复合物疫苗,能保持疫苗中抗原的免疫原性,并可减轻疫苗的毒副作用,提高疫苗的安全性,其免疫效果比常规活苗好。 相似文献
995.
黄芪多糖佐剂对Ⅰ型鸭疫里氏杆菌灭活疫苗的作用研究 总被引:2,自引:0,他引:2
本研究以Ⅰ型鸭疫里氏杆菌武汉分离株为菌种,经复苏、增菌、浓缩、灭活后与黄芪多糖佐剂混合制成灭活疫苗。试验鸭在5日龄时按最佳免疫剂量(0.3 mL/只)注射疫苗,免疫后第3、7、10、14、21天的攻毒保护率分别为100%、90%、100%、100%、90%,免疫后第3天即能用琼脂扩散法在血清中检测出Ⅰ型鸭疫里氏杆菌特异性抗体,效价逐渐升高,至免疫后第10天达高峰(P<0.01)。试验结果表明,该灭活疫苗能有效预防鸭传染性浆膜炎。 相似文献
996.
997.
998.
为了更好地防制猪链球菌病,从沈阳市多个地区疑患猪链球菌病的病死猪中分离到9株链球菌,通过细菌分离鉴定确定这9株链球菌中有1株为猪链球菌,其它8株为马链球菌兽疫亚种;致病性试验结果表明,9株均具有致病性;药敏试验筛选出了对各菌株高敏的药物;选择2株链球菌制备疫苗并免疫仔猪,结果证明有较好的免疫原性,可以作为疫苗株预防猪链球菌病。 相似文献
999.
鸡爪槭转色期叶色变化生理研究 总被引:2,自引:0,他引:2
以杭州植物园与花港观鱼公园的鸡爪槭(Acer palmatum Thunb)成龄植株为材料,测定10月下旬至12月上旬鸡爪槭转色期叶绿素、花色素苷和可溶性糖含量的变化,比较不同光照强度及温度对叶色的影响。结果表明:叶片中叶绿素含量随时间的变化逐渐降低,树冠背阴面叶片中的叶绿素含量显著高于向阳面,阳面东向显著高于阳面西向;花色素苷的含量则随时间不断升高,11月21日之后变化尤其显著;可溶性糖含量在11月21日之前迅速增加,之后趋于稳定。温度与叶绿素含量呈显著正相关,与花色素苷和可溶性糖含量成显著负相关。 相似文献
1000.
Prodip Kumar Sarkar Ai Egusa Mei Matsuzaki Tomohiro Sasanami 《The Journal of Poultry Science》2021,58(3):186
Sperm motility is considered as one of the most important traits for successful fertilization, but the motility of an ejaculated sperm decreases with time when stored as liquid. It is reported that seminal plasma serves as a nutrient rich medium for sperm and plays an important role in sperm motility and its fertilization ability. Several studies have reported that imidazole dipeptides such as anserine and carnosine affect sperm motility and its fertilization ability in mammals. In this study, we report the presence of anserine and carnosine in the male reproductive tract of the Japanese quail. Abundant levels of anserine (44.46 µM) and carnosine (41.75 µM) were detected in the testicular fluid and seminal plasma respectively using the amino acid analyzer; however, seminal plasma solely contained carnosine. When the ejaculates were incubated with anserine or carnosine, we found that both the dipeptides improve sperm motility parameters such as straight line velocity, curvilinear velocity, average path velocity and amplitude of lateral head displacement after in vitro sperm storage at 15°C. These results indicate that imidazole dipeptides are present in the male reproductive tract and may improve sperm quality during in vitro sperm storage in the liquid states. 相似文献