全文获取类型
收费全文 | 1621篇 |
免费 | 112篇 |
国内免费 | 107篇 |
专业分类
林业 | 222篇 |
农学 | 189篇 |
基础科学 | 88篇 |
257篇 | |
综合类 | 302篇 |
农作物 | 135篇 |
水产渔业 | 131篇 |
畜牧兽医 | 338篇 |
园艺 | 46篇 |
植物保护 | 132篇 |
出版年
2024年 | 8篇 |
2023年 | 21篇 |
2022年 | 35篇 |
2021年 | 75篇 |
2020年 | 47篇 |
2019年 | 43篇 |
2018年 | 57篇 |
2017年 | 70篇 |
2016年 | 58篇 |
2015年 | 67篇 |
2014年 | 52篇 |
2013年 | 107篇 |
2012年 | 86篇 |
2011年 | 97篇 |
2010年 | 98篇 |
2009年 | 83篇 |
2008年 | 107篇 |
2007年 | 98篇 |
2006年 | 82篇 |
2005年 | 74篇 |
2004年 | 38篇 |
2003年 | 38篇 |
2002年 | 32篇 |
2001年 | 33篇 |
2000年 | 40篇 |
1999年 | 42篇 |
1998年 | 29篇 |
1997年 | 34篇 |
1996年 | 30篇 |
1995年 | 30篇 |
1994年 | 19篇 |
1993年 | 27篇 |
1992年 | 15篇 |
1991年 | 13篇 |
1990年 | 8篇 |
1989年 | 8篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1974年 | 1篇 |
1969年 | 1篇 |
1965年 | 2篇 |
1964年 | 1篇 |
1963年 | 3篇 |
1944年 | 1篇 |
排序方式: 共有1840条查询结果,搜索用时 15 毫秒
61.
Menşure Özgüven Bilge Şener Ilkay Orhan Nazım Şekeroğlu Muzaffer Kirpik Murat Kartal Ipek Peşin Zülküf Kaya 《Industrial Crops and Products》2008,27(1):60-64
Artemisia annua L. is an aromatic-antibacterial herb that destroys malarial parasites, lowers fevers and checks bleeding, and of which the secondary compound of interest is artemisinin. The objective of the present study was to determine yield, yield components and artemisinin content of A. annua L. grown under four nitrogen applications (0, 40, 80 and 120 kg ha−1) in the Çukurova region of Turkey in 2004 and 2005. Field trials were conducted at Çukurova University, Agricultural Faculty Field Crops Department. In the study, plant height, number of branches, fresh herbage yield, dry herbage yield, fresh leaf yield, dry leaf yield, essential oil content and artemisinin content (by high performance liquid chromatography, HPLC) were examined. By analysis of variance, nitrogen doses had no any statistical effect on the traits investigated except for artemisinin content. Artemisinin content of the dried leaves were significantly affected by nitrogen applications, which varied from 6.32 to 27.50 mg 100 g−1. Contents were from 120 and 80 kg ha−1 nitrogen for the years of 2004 and 2005, respectively. 相似文献
62.
63.
板栗良种基地营建技术研究 总被引:1,自引:0,他引:1
在江苏省溧阳市龙潭林场,进行了板优良品种的收集,良种优良,良种繁育,板栗嫩枝扦插等一系列营建技术研究,取得了明显的经济,社会效益。 相似文献
64.
A new monocyclic triterpene ester (1) was isolated from the rhizomes of Iris germanica from Turkey. Structure elucidation of compound (1) was carried out by the combined application of HMQC, HMBC, DEPT, COSY and NOESY experiments and named as iristectorone K. 相似文献
65.
Antibacterial activity of seed proteins of Robinia pseudoacacia 总被引:1,自引:0,他引:1
A low molecular weight cationic peptide was isolated from Robinia pseudoacacia seed and tested in vitro against seven bacteria (Corynebacterium michiganense, Staphylococcus aureus, Bacillus subtilis, Erwinia carotovora subsp. carotovora, Pseudomonas syringae pv syringae, Xanthomonas campestris pv campestris, and Escherichia coli). The peptide inhibited the growth of the tested strains. The effective concentrations required for 50% inhibition of bacterial growth ranged between 20 and 120 microg ml(-1) protein. S. aureus was found to be the most sensitive strain, however, E. coli was not affected much when compared with others. Reduction of antibacterial activity of the peptide with CaCl2 addition into the growth medium was also observed. 相似文献
66.
秦岭松栎林带生物量及其营养元素分布特征 总被引:22,自引:2,他引:22
秦岭脱齿栎林、油松林和华山林(包括0-60cm土层)营养元素总贮量达29.2500-390.1739t.hm^-2,其大小为锐齿栎林>华山松>油松林,土壤中营养现贮量占系统总量的93.10%-99.39%,植被层和凋落物层仅占0.57%-3.00%和0.10%-1.99%;3林分乔木层生物量、木材蓄积量和营养元素积累量平均值分别为120.483t.hm^-2,129.384m^3.hm^-2和1226.9kg.hm^-2,锐齿栎林>油松林>华山松林。3林分林下植被层生物量现存量和营养元素积累量平均值分别为1.553t.hm^-2和53.1kg.hm^-2,锐齿栎林最大,华山松林最小。林下凋落物现存量和营养元素积量平均值分别为17.475t.hm^-2和502.5kg.hm^-2,3林分凋落物现存量、营养元素含量及其积累量都存在明显的差异。锐齿栎林、油松林和华山松林营养元素年吸收量、归还量、存留量和平均归还率分别为33.4、147.2和264.3,195.6、66.9和84.1,138.8、80.4和180.2kg.hm^-2和0.585、0454和0.318,3林分各营养元素的年吸收量,归还量和存留量也存在一定的差异,锐齿栎林干和皮中Ca和Mg含量远远高于油松林和华山松林的,锐齿栎林多代连作势必导致营养元素的大量流失,特别是Ca和Mg,会破坏土壤原有离子动态平衡,引起林地土壤理化性质改变,林地生产潜力逐渐下降。 相似文献
67.
Ecballium elaterium fruit juice is used for the treatment of sinusitis in Turkish folk medicine. The aim of this study was to increase the yield of cucurbitacin B, an anti-inflammatory compound previously isolated in various organs of E. elaterium, through tissue culture techniques. Higher yields of cucurbitacin B (1.126%) were obtained from the first subculture calluses from stem nodes in the presence of benzyl adenine (BA; 1 mg/l) and naphtalene acetic acid (NAA; 0.1 mg/l) in comparison with the yields obtained from plant material (0.01%). 相似文献
68.
Forty‐five basidiocarp specimens of Heterobasidion were collected from native Abies species in three locations in western Turkey: A. nordmanniana ssp. bornmülleriana in Bolu province, A. nordmanniana ssp. equi‐trojani in Balikesir province and A. cilicica in Antalya province. Pure cultures were isolated from the basidiocarps and identified to the species level with the aid of mating tests. All the specimens proved to belong to the species Heterobasidion abietinum. This root rot fungus is common in the forests investigated and appears to be relatively virulent on Abies in Turkey. This is the first report of H. abietinum outside Europe. 相似文献
69.
We investigated the correlation of large fires([300 ha) from 1992 to 2013 within the borders of the Antalya Regional Directorate of Forestry using the Keetch–Byram drought index(KBDI). Daily KBDI values were calculated for each year, and values for the period before the year 2000 differed significantly from those after2000. After 2000(large fires occurred in 2004, 2006, 2007,2008, 2010, and 2013), when KBDI values increased, the KBDI, but not the number of fires, was inversely correlated with the natural log of the burned area(NLBA). While there were both high and low KBDI values when the NLBA was small, only high KBDI values were associated with high NLBA values. Particularly for logarithmic values of 4 and higher, KBDI values increased in parallel with increases in NLBA values. On the basis of a Mann–Whitney U test done in addition to a Pearson correlation test, we found that when the burned areas were grouped according to small and large areas, the KBDI could be used to distinguish the two groups. Using a conditional probability analysis, we found that 4th, 5th and 6th class KBDI values may lead to large fires at the 60 % possibility.Similarly, the possibility of large fires greater than the median burned area in any given 6 years was found to be48 %. In addition, while the mean value of KBDI is 390.51 for the period from May to September for these 6 years, it is 359.93 for the other years. Consequently, the area burned also increased as the KBDI classes(Class 0: 0–99, Class 1:100–199, Class 2: 200–299, Class 3: 300–399, Class 4:400–499, Class 5: 500–599, Class 6: 600–699, and Class 7:700–800) increase. 相似文献
70.