全文获取类型
收费全文 | 1055篇 |
免费 | 53篇 |
专业分类
1108篇 |
出版年
2024年 | 3篇 |
2023年 | 11篇 |
2022年 | 29篇 |
2021年 | 34篇 |
2020年 | 15篇 |
2019年 | 17篇 |
2018年 | 17篇 |
2017年 | 25篇 |
2016年 | 30篇 |
2015年 | 34篇 |
2014年 | 32篇 |
2013年 | 53篇 |
2012年 | 74篇 |
2011年 | 84篇 |
2010年 | 53篇 |
2009年 | 45篇 |
2008年 | 59篇 |
2007年 | 37篇 |
2006年 | 33篇 |
2005年 | 35篇 |
2004年 | 36篇 |
2003年 | 43篇 |
2002年 | 38篇 |
2001年 | 35篇 |
2000年 | 36篇 |
1999年 | 33篇 |
1998年 | 7篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1993年 | 3篇 |
1992年 | 12篇 |
1991年 | 12篇 |
1990年 | 18篇 |
1989年 | 17篇 |
1988年 | 9篇 |
1987年 | 12篇 |
1986年 | 9篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1983年 | 9篇 |
1982年 | 3篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1977年 | 6篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1973年 | 3篇 |
1972年 | 4篇 |
1970年 | 2篇 |
1968年 | 2篇 |
排序方式: 共有1108条查询结果,搜索用时 0 毫秒
51.
Mukesh Meena Andleeb Zehra Prashant Swapnil Manish Kumar Dubey Chandra Bali Patel R. S. Upadhyay 《Archives Of Phytopathology And Plant Protection》2017,50(7-8):317-329
Tomato is considered as one of the most important sources of nutrients such as lycopene, β-carotene, flavonoids, ascorbic acid (vitamin C) and hydroxyl-cinnamic acid derivatives. The quality and quantity of nutrients in tomato fruits were decreased during the severe infection of Alternaria alternata. The present study deals with the estimation of lycopene, β-carotene, phenolic and ascorbic acid content in tomato fruits which were infected with A. alternata and its toxins such as tenuazonic acid (TeA), alternariol (AOH) and alternariol monomethyl ether (AME). The lycopene, β-carotene, ascorbic acid and phenolic content were found lowest in pathogen-infected fruits i.e. (0.66 ± 0.03 mg/g), (0.14 ± 0.01 mg/g), (1.89 ± 0.2 mg/g) and (0.58 ± 0.05 mg/g), respectively, followed by toxins-treated samples as compared to the control. The results concluded that A. alternata mostly affects the nutritional values of tomato fruits due to the combined effect of the toxins. 相似文献
52.
Eight anti-coccidial drugs were examined for their efficacies in preventing development of Neospora caninum in bovine monocyte cell cultures. Lasalocid sodium (0.05 microgram/ml), monensin sodium (0.05 microgram/ml), piritrexim (0.01 microgram/ml), pyrimethamine (0.05 microgram/ml), and trimethoprim (5.0 micrograms/ml) were effective in preventing development of intracellular N. caninum tachyzoites (P less than 0.05). No differences (P greater than 0.05) in mean numbers of infected cells compared to controls were observed in cultures treated with amprolium hydrochloride (10.0 micrograms/ml), sulfadiazine (200.0 micrograms/ml), and sulfamethoxazole (200.0 micrograms/ml). 相似文献
53.
Abhimanyu Jogawat Shreya Saha Madhunita Bakshi Vikram Dayaman Manoj Kumar Meenakshi Dua Ajit Varma Ralf Oelmüller Narendra Tuteja Atul Kumar Johri 《Plant signaling & behavior》2013,8(10)
Piriformospora indica association has been reported to increase biotic as well as abiotic stress tolerance of its host plants. We analyzed the beneficial effect of P. indica association on rice seedlings during high salt stress conditions (200 and 300 mM NaCl). The growth parameters of rice seedlings such as root and shoot lengths or fresh and dry weights were found to be enhanced in P. indica-inoculated rice seedlings as compared with non-inoculated control seedlings, irrespective of whether they are exposed to salt stress or not. However, salt-stressed seedlings performed much better in the presence of the fungus compared with non-inoculated control seedlings. The photosynthetic pigment content [chlorophyll (Chl) a, Chl b, and carotenoids] was significantly higher in P. indica-inoculated rice seedlings under high salt stress conditions as compared with salt-treated non-inoculated rice seedlings, in which these pigments were found to be decreased. Proline accumulation was also observed during P. indica colonization, which may help the inoculated plants to become salt tolerant. Taken together, P. indica rescues growth diminution of rice seedlings under salt stress. 相似文献
54.
55.
Nineteen white-tailed deer (Odocoileus virginianus) from 5 counties in Alabama were examined for infection with Toxoplasma gondii. Twenty-gram samples of heart tissue were bioassayed in mice, serum was examined for T. gondii antibodies using the direct agglutination test, and sections of heart muscle were examined histologically for tissue cysts. Toxoplasma gondii was isolated from 4 of 19 (21%) white-tailed deer hearts. Antibody titers of greater than or equal to 1:50 were found in sera from 7 of 16 (44%) white-tailed deer. Histological examinations of tissue sections from white-tailed deer hearts were negative for T. gondii. 相似文献
56.
Asexual stages of Sarcocystis neurona were seen in cultured bovine monocytes (M617) inoculated with tissue homogenates from the spinal cord of a horse with naturally acquired protozoal myelitis. Organisms first were observed as intracytoplasmic schizonts and later as motile extracellular zoites capable of infecting surrounding M617 cells. Parasites most often occurred as clusters of merozoites dispersed throughout the host cell cytoplasm; however, schizonts also contained merozoites arranged in a radial fashion surrounding a prominent residual body. Schizonts divided by endopolygeny. The parasite has been maintained beyond 280 days in the laboratory by serial passage of infected M617 cells. 相似文献
57.
Sylvain Dubey Julien Leuenberger Nicolas Perrin 《Biological journal of the Linnean Society. Linnean Society of London》2014,112(3):442-449
The marsh frog (Pelophylax ridibundus) has been introduced in many areas in Central and Western Europe as a result of commercial trade with Eastern Europe, and is rapidly replacing the native pool frog (P. lessonae). A large number of Pelophylax species are distributed in Eastern Europe and the strong phenotypic similarity between these species is rendering their identification hazardous. Consequently, alien populations of Pelophylax might not strictly be composed of P. ridibundus as previously suspected. In the present study, we analysed the cytochrome‐b and NADH dehydrogenase subunit 3 genes of introduced and native Pelophylax species from Switzerland (299 individuals) in order to properly identify the source populations of the invaders and the genetic status of the native species. Our study highlighted the occurrence of several genetic lineages of invasive frogs in western Switzerland. Unexpectedly, we also showed that several populations of the native pool frog (P. lessonae) cluster with the Italian pool frog P. bergeri from central Italy (considered by some authors as a subspecies of P. lessonae). Hence, these populations are probably also the result of introductions, meaning that the number of native P. lessonae populations is fewer than expected in Switzerland. These findings have important implications concerning the conservation of the endemic pool frog populations, as the presence of multiple alien species could strongly affect their long‐term subsistence. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 112 , 442–449. 相似文献
58.
Singh Anjana Pandey K.D. Dubey R.S. 《World journal of microbiology & biotechnology》1999,15(2):277-282
Reverse micelles serve as a novel tool to entrap enzymes and microbial whole cells within aqueous pockets and can be of great use in enhancing the efficiency and sustainability of the biological system. Photosynthetic bacterium Rhodopseudomonas sphaeroides entrapped inside the aqueous pool of reverse micelles prepared from benzene-sodium lauryl sulphate exhibited 25-fold enhancement of H2 photoproduction rate (1.67 ml H2 [mg protein]–1 h–1) compared to cells suspended in normal aqueous medium. Hydrogen photoproduction by the bacterium was catalysed by the nitrogenase enzyme system which was supported at a low light intensity of 12 Em–2 sec–1 photon flux energy at a wavelength of 520 nm. The optimum temperature for the process was 40 °C. 相似文献
59.
Mukesh Meena Prashant Swapnil Andleeb Zehra Manish Kumar Dubey R. S. Upadhyay 《Archives Of Phytopathology And Plant Protection》2017,50(13-14):629-648
Trichoderma spp. are well-known biological agents that have significant antagonistic activity against several plant pathogenic fungi. In the present study, Trichoderma spp. were tested in vitro for their antagonistic activity against different spp. of Fusarium and Alternaria viz. Alternaria alternata, A. brassicae, A. solani, Fusarium oxysporum and F. solani using dual plate assay and by the production of volatile and non-volatile compounds. The results obtained revealed that Trichoderma harzianum and T. viride effectively inhibited the growth and spore production of different spp. of Fusarium and Alternaria. The highest growth inhibition was found in A. alternata 62.50% and 60.00% by non-volatile compounds of T. harzianum and T. viride, respectively. Similarly, the volatile compounds inhibit the maximum growth of A. alternata 40.00% and 35.00% by T. harzianum and T. viride, respectively. Volatile and non-volatile compounds of Trichoderma spp. were analysed by GC-MS technique and the properties of distinguished compounds showed antifungal, antimicrobial and antibiotic activities. Volatile compounds of T. harzianum and T. viride showed highest percent abundance for glacial acetic acid (45.32%) and propyl-benzene (41.75%), respectively. In case of non-volatile compounds, T. harzianum and T. viride showed D-Glucose, 6-O-α-D-galactopyranosyl- (38.45%) and 17-Octadecynoic acid (36.23%), respectively. The results of present study confirmed that T. harzianum can be used as a promising biological control agent against Alternaria and Fusarium spp. that cause diseases in various vegetables and crops. 相似文献
60.
Multiple matings result in varying paternity share based on mating interval and order. Thus, assessing the effect of mating interval and order on patterns of sperm usage and paternity is crucial. We designed consecutive and delayed double-mating experiments to investigate paternity variation in ladybird, Menochilus sexmaculatus (Fabricius) (Coleoptera: Coccinellidae), using two distinct morphs of the species as phenotypic markers of paternity. The time to commence mating, copulation duration and reproductive output were recorded. The morphs of the offspring from the two setups were taken as a measure of paternity accumulated by the males. The time to commence mating decreased for the second mating in the consecutive mating treatment, while the reverse was observed in the delayed mating treatment. Consecutive double matings reduced the mating duration. Fecundity increased when second mating occurred after a few days, though percent egg viability remained unaffected. The second male accrued higher paternity (P2?=?0.61) than the first male (P1?=?0.39) in the consecutive mating treatment, while in the delayed mating treatment, the overall paternity share of the first 0.49 (P1) and last male was equal 0.51 (P2). Thus, our study revealed that both mating order and the time interval between successive matings regulate the male paternity share. This finding is reported for the first time in this ladybird species. 相似文献