全文获取类型
收费全文 | 419篇 |
免费 | 16篇 |
国内免费 | 75篇 |
学科分类
生物科学 | 510篇 |
出版年
2023年 | 5篇 |
2022年 | 5篇 |
2021年 | 12篇 |
2020年 | 4篇 |
2019年 | 3篇 |
2018年 | 7篇 |
2017年 | 1篇 |
2016年 | 6篇 |
2015年 | 7篇 |
2014年 | 12篇 |
2013年 | 26篇 |
2012年 | 22篇 |
2011年 | 18篇 |
2010年 | 15篇 |
2009年 | 41篇 |
2008年 | 38篇 |
2007年 | 25篇 |
2006年 | 23篇 |
2005年 | 20篇 |
2004年 | 22篇 |
2003年 | 13篇 |
2002年 | 13篇 |
2001年 | 13篇 |
2000年 | 13篇 |
1999年 | 18篇 |
1998年 | 13篇 |
1997年 | 13篇 |
1996年 | 12篇 |
1995年 | 11篇 |
1994年 | 9篇 |
1993年 | 8篇 |
1992年 | 4篇 |
1991年 | 10篇 |
1990年 | 5篇 |
1989年 | 6篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1985年 | 7篇 |
1984年 | 1篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1979年 | 4篇 |
1971年 | 1篇 |
1970年 | 2篇 |
排序方式: 共有510条查询结果,搜索用时 15 毫秒
1.
《Biocatalysis and Biotransformation》2013,31(1-4):353-360
Experiments with dyed and undyed cotton, using different cellulose concentration and with or with out mechanical action showed a high effect of those factors. The process with mechanical action have a higher weight-loss. Dyed cotton with vat and sulfur dyes have almost die same weight-loss than undyed cotton, but on reactive dyed cotton the cellulase hydrolysis is shorter. It was also verified a decrease of hydrolysis extent with an increase of the reactive dye concentration on the cotton substrate. Some synergism due to the enzyme concentration was apparently observed on the changes of the length of the leaving sugars. 相似文献
2.
Khuram Shahzad Abdul Hai Nadeem Kizilbash Jawaria Ambreen Jamal Alruwaili 《Bioinformation》2013,9(9):471-476
DNA γ is approximately half of the size of Begomovirus DNA. It encodes a γC1 gene that is conserved in position and size. This
gene has the capacity to encode a 13 to 14 kDa protein comprising 118 amino acid residues. It has been shown earlier that γC1
protein is necessary for inducing symptoms of cotton leaf curl disease. The structure for γC1 (CLCuDγ01-Pakistan) is still
unknown. Therefore, a model of γC1 (CLCuDγ01-Pakistan) was developed using DoBo and I-TASSER servers followed by
validation by PROCHECK and VERIFY 3D servers. The developed model provides an insight in a role for this multifunctional
protein in causing Cotton Leaf Curl Disease (CLCuD). A possible function of this protein might be the suppression of RNAsilencing
in cotton plants. 相似文献
3.
4.
5.
6.
《Saudi Journal of Biological Sciences》2020,27(8):2106-2110
American bolloworm, Helicoverpa armigera Hubner (Noctuidae: Lepidoptera) is considered as a major pest of various crops all over the world. It is mainly controlled by indiscriminate use of synthetic insecticides in the world due to which this pest developed resistance to most of the available insecticides. Therefore, in the current study, the efficacy of virulent strain of HaNPV (0.5 × 109 PIB/ml) alone and in combination with recommended doses of spintoram (20 g/100 L of water) and emamectin benzoate (200 ml/100 L of water) was tested in field. The combination of HaNPV with spintoram and emamectin benzoate 100% reduced the larval population as compared to emamectin benzoate and HaNPV alone. This suggested that the combination of spintoram and emamectin benzoate with HaNPV could be used in field to manage the infestation of H. armigera. 相似文献
7.
Direct and residual effects of nitrogen fertilization, foliar application of potassium and plant growth retardant on Egyptian cotton growth, seed yield, seed viability and seedling vigor 下载免费PDF全文
In order to obtain high productivity for a cotton crop, one of the major requirements is to establish an adequate plant population. The use of good-quality seed may ultimately be the best approach to attain this goal problem. The objective of this research was to study the effect of N-fertilization (at rates of 95.2 and 142.8 kg of N ha?1), foliar application of K (at rates of 0, 0.38, 0.77, 1.15 kg of K2O ha?1, applied twice during square initiation and boll development stages) and the plant growth retardant (PGR), mepiquat chloride (applied twice, 75 days after planting at 0.0 [control] and 0.048 kg a.i. ha?1, and 90 days after planting at 0.0 [control] and 0.024 kg a.i. ha?1), on seed yield, viability, and seedling vigor of Egyptian cotton (Gossypium barbadense cv. Giza 86). A field experiment was conducted at the Agricultural Research Center, Giza, Egypt in two growing seasons. Growth, mineral uptake, seed yield per plant and per ha, seed weight, seed viability, seedling vigor and cool germination test performance were all found to increase significantly due to the addition of the high N-rate, the foliar application of three potassium concentrations, and the PGR mepiquat chloride. The N and K rates as well as application of mepiquat chloride had no significant effect on the germination rate index in both seasons. Under the conditions of this study, applying N at a rate of 142.8 kg ha?1 combined with spraying cotton plants with K2O at 1.15 kg ha?1 and with mepiquat chloride at 0.048 + 0.024 kg ha?1 were found to improve seed yield as well as seed viability and seedling vigor in the next season. 相似文献
8.
黄山木兰的丛枝菌根定殖状况 总被引:1,自引:0,他引:1
在原产地和引种栽培地采集了国家珍稀濒危植物黄山木兰(Magnolia cylindrica)的根样及其根际土壤样品,研究了根中丛枝菌根真菌(AMF)的定殖状况。AMF在两地黄山木兰的根中均有定殖,并形成典型的Paris-type类型丛枝菌根(AM),原产地黄山木兰的AMF定殖率高于栽培地。用湿筛沉淀法从两地黄山木兰根际土壤中共分离鉴定出5属22种AMF,两地AMF群落相似性系数为0.96。原产地黄山木兰的AMF孢子密度高于栽培地,而Shannon-Wiener多样性指数低于栽培地。研究结果表明,黄山木兰引种栽培后并没有对其根际土壤中AMF的群落结构造成大的改变。 相似文献
9.
Biotic and abiotic factors that influence the avian distribution in a dry zone wetland was investigated by studying the distribution
of Asian Openbill (Anastomus oscitans), Cotton Pygmy-goose (Nettapus coromandelianus) and Pheasant-tailed Jacana (Hydrophasianus chirurgus) in Anavilundawa Ramsar sanctuary in Sri Lanka in 2006. Their distribution was recorded in Anavilundawa, Suruwila and Maiyawa
reservoirs, their catchments and respective paddy fields, through line transects. The floral cover of surface water was recorded
by floating quadrates. Water lily (Nymphea spp.) was the dominant flora in Anavilundawa reservoir, invasive water hyacinth (Eichhornia crassipes) in Suruwila reservoir and a native lotus (Nelumbo nucifera) in Maiyawa reservoir, respectively. Anavilundawa area had a higher distribution of birds than in the other two areas. Among
the three species observed, Asian Openbill distribution was mainly restricted to Anavilundawa whereas Pheasant-tailed Jacana
was present in all three areas. Nesting of Asian Openbill occurred only in Anavilundawa while nesting of Pheasant-tailed Jacana
was only observed in Maiyawa. Among the three species recorded, Cotton Pygmy-goose numbers were the least. Asian Openbill
preferred dead trees and trees with no leaves for nesting and perching over live trees. It is concluded that the spread of
invasives such as Water hyacinth and Salvinia (Salvinia molesta) forming mats over surface water have reduced the abundance of habitat specialists like Cotton Pygmy-goose. 相似文献
10.
Roberta Cassano Sonia Trombino Teresa Ferrarelli Rita Muzzalupo Lorena Tavano Nevio Picci 《Carbohydrate polymers》2009,78(3):639-641
We prepared cellulose cotton fibers containing ampicillin moieties and evaluated their antibacterial activity. In spite of recent progress in experimental and clinical medicine, the problem of chronic wounds treatment remains to be solved. In fact conventional methods are based on solutions of antibiotics and antiseptics and ointment bandages but the efficacy of this method is low and so the idea to use modified cotton gauzes would have to prevent infections insorgence during wounds healing. Ampicillin, a large spectrum antibiotic, was covalently coupled to cellulose backbone of hydrophilic cotton fibers by a heterogeneous synthesis to produce a functionalized biopolymer with a satisfactory degree of substitution (DS) and antibacterial activity. The obtained biopolymer was characterized by infrared spectroscopy (FT-IR). Finally, the antibacterial activity in inhibiting microorganism growth in Petri dishes, was evaluated. The results suggested that these biomaterials posses an excellent “in vitro” antibacterial activity and so they can be efficiently employed in biomedical fields for chronic wounds management to ensure a valid protection against infections and contaminations. Biopolymers so functionalized were found to be very efficient to contrast sensible bacteria growth. 相似文献