全文获取类型
收费全文 | 1416篇 |
免费 | 100篇 |
国内免费 | 115篇 |
专业分类
林业 | 60篇 |
农学 | 147篇 |
基础科学 | 29篇 |
160篇 | |
综合类 | 526篇 |
农作物 | 162篇 |
水产渔业 | 189篇 |
畜牧兽医 | 104篇 |
园艺 | 21篇 |
植物保护 | 233篇 |
出版年
2024年 | 6篇 |
2023年 | 30篇 |
2022年 | 47篇 |
2021年 | 59篇 |
2020年 | 45篇 |
2019年 | 63篇 |
2018年 | 38篇 |
2017年 | 64篇 |
2016年 | 58篇 |
2015年 | 61篇 |
2014年 | 72篇 |
2013年 | 87篇 |
2012年 | 99篇 |
2011年 | 88篇 |
2010年 | 63篇 |
2009年 | 73篇 |
2008年 | 71篇 |
2007年 | 73篇 |
2006年 | 76篇 |
2005年 | 61篇 |
2004年 | 45篇 |
2003年 | 38篇 |
2002年 | 26篇 |
2001年 | 37篇 |
2000年 | 27篇 |
1999年 | 38篇 |
1998年 | 25篇 |
1997年 | 20篇 |
1996年 | 9篇 |
1995年 | 23篇 |
1994年 | 16篇 |
1993年 | 18篇 |
1992年 | 16篇 |
1991年 | 8篇 |
1990年 | 9篇 |
1989年 | 12篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1986年 | 8篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1962年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1631条查询结果,搜索用时 46 毫秒
121.
122.
[目的]研究烟草赤星病发病规律及防治技术.[方法]比较不同品种、不同施肥量、不同移栽期、不同药剂对赤星病的抗病、发病关系以及防治效果.[结果]中烟103抗性最强,中烟100、K326次之,云烟87、CF205最差.N、P、K比例以1.0∶1.2∶3.0或1.0∶1.5∶3.0为宜,氮肥用量一般施纯氮67.5~90.0 kg/hm2为宜.5月5~20日移栽是最适宜的种植时期.防治赤星病效果最好为40%菌核净可湿性粉剂,防效为53.44%.[结论]为烟草赤星病的防治提供参考. 相似文献
123.
T. VEHANEN 《Fisheries Management and Ecology》1995,2(2):121-134
Abstract Lake-to-lake variation in brown trout, Salmo trutta m. lacustris L., yield from stocking was examined in 34 lakes in northern Finland. The trout were mainly stocked as 2–3-year-old fish. Catch statistics were compiled with information on water quality, water level fluctuations, fishing effort and lake geomorphology. Absolute brown trout yields (kgha-1 ) increased with increasing stocking rate, but there was an indication of non-linearity at higher stocking densities. Relative yields (kg per thousand trout released) were highest at low stocking rates. Stepwise multiple regression analysis was used to determine the best predictive model for lake-to-lake variability in brown trout yields. Seventeen measured regressands were used initially, and then replaced with scores obtained in a principal component analysis of highly correlated water quality variables and species-specific fish yields. Three major determinants of brown trout yields in these lakes were found in both analyses: fish community, stocking rate and fishing effort. Brown trout yields from stocking were higher in lakes with proportionally high yields of vendace or vendace and whitefish and proportionally low yields of pike. 相似文献
124.
全球性肥胖流行问题愈发严峻,而脂肪组织本身可能是解决这个问题的关键。人和哺乳动物体内存在两种脂肪组织,发挥着截然相反的作用。与白色脂肪组织存储机体过剩的能量不同,棕色脂肪组织中存在独特的解偶联蛋白,能将脂肪酸氧化磷酸化,释放热能,增加能量消耗。因此,通过激活棕色脂肪组织产热,加速体内储存的脂质氧化磷酸化,成为了一种新的预防和治疗肥胖的手段。论文阐述影响棕色脂肪产热活性的因素以及相关机制,旨在为肥胖的治疗提供新的思路和方向。 相似文献
125.
《Soil Science and Plant Nutrition》2013,59(6):870-872
Abstract Gram-positive bacterium BRF-1 isolated from the rhizosphere of root-rotten diseased soybean plants shows strong antifungal activity on plates. In the present study, the ability of BRF-1 to control brown stem rot disease and to promote plant growth was examined using soybean plants grown in pots. Brown stem rot is a severe soil-borne disease of soybean that is caused by the pathogenic fungus Phialophora gregata. Eighteen-day-old soybean seedlings were grown in a mixture of soil (40 mL) and BRF-1 suspension (10 mL) and were dipped in a suspension of P. gregata (106 c.f.u. mL?1), and the severity of the disease was judged 62 days after the fungal inoculation. Inoculation with BRF-1 at 107 and 108 c.f.u. mL?1 significantly lowered the severity of the disease. Soybean seeds incubated in 100 mL of the BRF-1 suspension (2 × 106 c.f.u. mL?1) were sown in pots filled with sand, and plants were collected 7 days after emergence. The dry weight increase in shoots and roots and mineral absorption were significantly stimulated by the inoculation. These results suggest that BRF-1 might be an effective biocontrol agent to manage brown stem rot disease in soybean. The 16S rDNA sequence of BRF-1 showed high homology with sequences of Paenibacillus polymyxa strains (e.g. 99.7% identity with P. polymyxa strain WY110). 相似文献
126.
Aydin Adiloglu Sevinç Adiloglu Esin Gonulsuz Nureddin Oner 《Archives of Agronomy and Soil Science》2013,59(6):601-606
In this article the effect of different nitrogen fertilizer application on the availability of zinc (Zn) content in non calcic brown forest soil was investigated. For this purpose increasing rates of NH4Cl, (NH4)2S04; NH4N03 and Ca(N03)2.4H20 fertilizers were applied for having different physical and chemical properties in two soil samples. An incubation experiment was carried out over 4 months. The available Zn content of the soils was determined each month. According to the results the highest available Zn content of the soils was obtained from NH4Cl applied to the soils followed by (NH4)2S04; NH4N03 and Ca(N03)2.4H20 application to soil. At the end of the experiment the average available Zn content of non calcic brown forest soils for NH4Cl, (NH4)2S04; NH4N03 and Ca(N03)2.4H20 fertilizers are 0.93, 0.91, 0.88 and 0.77 mg kg?1, respectively. 相似文献
127.
128.
对棕熊精子体外获能前后和异种穿卵的超微结构观察表明,棕熊精子全长77μm,由头、颈和尾3部分组成.头部长7.3μm,宽2.5μm,主要由核、顶体及顶体后区组成;颈部由中心粒和9条纵行分节的节往组成;尾部全长68.2μm,其中中段长13.2μm,线粒体为65~68旋,主段中央为“9 2”的微管结构,其外方被9条致密纤维和纤维鞘包裹.精子获能前群集成簇,运动缓慢;获能后精子呈超激活运动.获能的精子质膜膨胀,顶体外膜囊泡化,引起顶体反应,质膜并未参加囊泡化.顶体反应完成后,仅有顶体内膜包在精子核膜的外面.棕熊精子与仓鼠的卵相互作用,多以赤道段和顶体后区附着于卵膜. 相似文献
129.
P.N. Sharma Y. Ketipearachchi K. Murata A. Torii S. Takumi N. Mori C. Nakamura 《Euphytica》2003,129(1):109-117
We have constructed a linkage map of the rice brown planthopper (BPH)resistance gene, Bph1. RFLP and AFLP markers were selected by thebulked segregant analysis and used in the mapping study of 262 F2sthat were derived from a cross of `Tsukushibare', a susceptible japonica cultivar, and `Norin-PL3', an authentic japonicaBph1-introgression line. Twenty markers were mapped within a 28.9-cMregion containing the Bph1 locus on the long arm of rice chromosome12. Combining the result of segregation analysis of BPH resistance by themass seedling test and that of the markers, the Bph1 locus wasmapped within a 5.8-cM region between two flanking markers. The closestAFLP markers, em5814N and em2802N, was at 2.7 cM proximal to theBph1 locus. Together with the previously constructed high-resolutionmap of bph2 locating the locus at ca. 10 cM proximal to the Bph1 locus, this improved version of the linkage map would facilitatepyramiding these two important BPH resistance genes. 相似文献
130.