全文获取类型
收费全文 | 928篇 |
免费 | 63篇 |
国内免费 | 1篇 |
出版年
2024年 | 4篇 |
2023年 | 8篇 |
2022年 | 38篇 |
2021年 | 53篇 |
2020年 | 36篇 |
2019年 | 60篇 |
2018年 | 57篇 |
2017年 | 30篇 |
2016年 | 52篇 |
2015年 | 48篇 |
2014年 | 54篇 |
2013年 | 68篇 |
2012年 | 83篇 |
2011年 | 59篇 |
2010年 | 35篇 |
2009年 | 30篇 |
2008年 | 31篇 |
2007年 | 31篇 |
2006年 | 26篇 |
2005年 | 32篇 |
2004年 | 26篇 |
2003年 | 23篇 |
2002年 | 26篇 |
2001年 | 8篇 |
2000年 | 5篇 |
1999年 | 2篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 7篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1989年 | 4篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1972年 | 1篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1967年 | 4篇 |
1965年 | 1篇 |
1962年 | 1篇 |
1961年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有992条查询结果,搜索用时 15 毫秒
1.
Mostafa Khajeh 《Biological trace element research》2010,138(1-3):337-345
In this study, silver nanoparticles were prepared and used for separation and preconcentration of manganese from biological samples. The technical feasibility of silver nanoparticles for manganese removal was investigated under batch studies. The effects of different parameters such as pH of solution, time (t), amounts of PAN (E), and silver nanoparticles (N) on the adsorption of manganese by silver nanoparticle were investigated using factorial design and response surface methodology based on Box–Behnken design. Thermodynamic parameters indicate the adsorption process to be exothermic. The limit of detection of the proposed method followed by inductively coupled plasma was found to be 0.08?µg L?1. The method was applied to determine of manganese in biological samples. 相似文献
2.
3.
A M Salama I Y Mostafa Y A El-Zawahry 《Acta biologica Academiae Scientiarum Hungaricae》1975,26(1-2):1-7
Chromatographic analysis led to the identification of monomethyl- and dimethyl-phosphates as metabolites resulting from the enzymatic degradation of 14C-labelled Dipterex in the buffer solutions and root tissues of broad bean and clover plants, as well as in the culture media of rhizobium leguminosarum and Rhizobium trifolii. The formation of 14CO2 from rhizobial cultures containing radioactive Dipterex suggests that some of the liberated methanol groups (during breakdown of Dipterex) are oxidatively degraded by the two Rhizobium spp. 相似文献
4.
Kathryn S. Evans Janneke Wit Lewis Stevens Steffen R. Hahnel Briana Rodriguez Grace Park Mostafa Zamanian Shannon C. Brady Ellen Chao Katherine Introcaso Robyn E. Tanny Erik C. Andersen 《PLoS pathogens》2021,17(3)
Parasitic nematodes cause a massive worldwide burden on human health along with a loss of livestock and agriculture productivity. Anthelmintics have been widely successful in treating parasitic nematodes. However, resistance is increasing, and little is known about the molecular and genetic causes of resistance for most of these drugs. The free-living roundworm Caenorhabditis elegans provides a tractable model to identify genes that underlie resistance. Unlike parasitic nematodes, C. elegans is easy to maintain in the laboratory, has a complete and well annotated genome, and has many genetic tools. Using a combination of wild isolates and a panel of recombinant inbred lines constructed from crosses of two genetically and phenotypically divergent strains, we identified three genomic regions on chromosome V that underlie natural differences in response to the macrocyclic lactone (ML) abamectin. One locus was identified previously and encodes an alpha subunit of a glutamate-gated chloride channel (glc-1). Here, we validate and narrow two novel loci using near-isogenic lines. Additionally, we generate a list of prioritized candidate genes identified in C. elegans and in the parasite Haemonchus contortus by comparison of ML resistance loci. These genes could represent previously unidentified resistance genes shared across nematode species and should be evaluated in the future. Our work highlights the advantages of using C. elegans as a model to better understand ML resistance in parasitic nematodes. 相似文献
5.
Thirty-eight genera and 81 species of fungi were isolated and identified from 120 samples of 24 kinds of spices collected from different places at Assiut Governorate, Egypt. Predominant genera wereAspergillus (25 species) andPenicillium (7 species) of whichA. flavus, A. niger, A. ochraceus, A. fumigatus, A. flavus var.columnaris, A. terreus, P. chrysogenum andP. corylophilum were the most commonly occurring. 相似文献
6.
Conjugative transfer functions of broad-host-range plasmid RK2 are coregulated with vegetative replication 总被引:24,自引:0,他引:24
Mostafa Motallebi-Veshareh † Dietmar Balzer Erich Lanka Grazyna Jagura-Burdzy Christopher M. Thomas 《Molecular microbiology》1992,6(7):907-920
The kilB locus (which is unclonable in the absence of korB) of broad-host-range plasmid RK2 (60 kb) lies between the trfA operon (co-ordinates 16.4 to 18.2 kb), which encodes a protein essential for vegetative replication, and the Tra2 block of conjugative transfer genes (co-ordinates 20.0 to 27.0 kb). Promoter probe studies indicated that kilB is transcribed clockwise from a region containing closely spaced divergent promoters, one of which is the trfA promoter. The repression of both promoters by korB suggested that kilB may also play a role in stable maintenance of RK2. We have sequenced the region containing kilB and analysed it by deletion and insertion mutagenesis. Loss of the KilB+ phenotype does not result in decreased stability of mini RK2 plasmids. However insertion in ORFI (kilBI) of the region analysed results in a Tra- phenotype in plasmids which are otherwise competent for transfer, demonstrating that this locus is essential for transfer and is probably the first gene of the Tra2 region. From the kilBI DNA sequence KilBI is predicted to be 34995 Da, in line with M(r) = 36,000 observed by sodium dodecyl sulphate/polyacrylamide gel electrophoresis, and contains a type I ATP-binding motif. The purified product was used to raise antibody which allowed the level of KilBI produced from RK2 to be estimated at approximately 2000 molecules per bacterium. Protein sequence comparisons showed the highest homology score with VirB11, which is essential for the transfer of the Agrobacterium tumefaciens Ti plasmid DNA from bacteria to plant cells. The sequence similarity of both KilBI and VirB11 to a family of protein export functions suggested that KilBI may be involved in assembly of the surface-associated Tra functions. The data presented in this paper provide the first demonstration of coregulation of genes required for vegetative replication and conjugative transfer on a bacterial plasmid. 相似文献
7.
In order to determine the extent and causative agents of dermatophytoses in the Hamadan region of West Iran; a study was made during a 9-month period from October 1991 to June 1992. A total of 7495 individuals were studied of whom 681 (9%) were suspect of having cutaneous mycoses. Among them dermatophytoses were the commonest infections (259/681=38%). Of 259 individuals infected with dermatophytes, tinea capitis were observed in 163 (62.9%); t. corporis in 27 (10.4%); t. manuum and t. cruris in 19 (7.3%) each; t. barbae and faciei in 14 (5.4%); t. pedis in 13 (5%) and t. unguium in 4 (1.5%). A total of 144 patients yielded dermatophyte cultures. The frequency of the isolated species in decreasing order was as follows: Trichophyton verrucosum, 78 (54.1%); T. schoenleinii, 48 (33.3%); Microsporum canis, 8 (5.5%); Epidermophyton floccosum, 5 (3.5%); T. mentagrophytes and M. gypseum, 2 (1.4%) each; T. tonsurans, 1 (0.7%). In conclusion, the most prevalent dermatophytosis in this region was t. capitis with the infecting agent of T. schoenleinii. 相似文献
8.
L R Bandara E W Lam T S S?rensen M Zamanian R Girling N B La Thangue 《The EMBO journal》1994,13(13):3104-3114
9.
Glycerol production by a highly glycerol-producing local isolate (Eurotium amstelodami) and a standard reference isolate (Aspergillus wentii) was markedly enhanced by high saline media. Glycerol concentration depended on the external osmotic. Thus, the highest glycerol
concentration was found in the presence of NaCl, followed by KCl, with considerably lower values for MgCl2 and CaCl2 saline media. With glucose (5–50%) used as a nonionic osmotic, low levels of glycerol were obtained and the main pool of
polyols was mannitol. Glycerol production was gradually increased with the increase of NaCl concentration of cheese whey,
reaching maxima by both organisms when whey was supplemented with 8% NaCl (total of 16% NaCl). The quantity of glycerol produced
byA. wentii was twice higher than that obtained byE. amstelodami on whey treated with 8% NaCl. 相似文献
10.