全文获取类型
收费全文 | 1009篇 |
免费 | 51篇 |
专业分类
1060篇 |
出版年
2023年 | 6篇 |
2022年 | 18篇 |
2021年 | 27篇 |
2020年 | 14篇 |
2019年 | 12篇 |
2018年 | 16篇 |
2017年 | 20篇 |
2016年 | 30篇 |
2015年 | 35篇 |
2014年 | 34篇 |
2013年 | 54篇 |
2012年 | 69篇 |
2011年 | 80篇 |
2010年 | 48篇 |
2009年 | 43篇 |
2008年 | 62篇 |
2007年 | 37篇 |
2006年 | 32篇 |
2005年 | 35篇 |
2004年 | 36篇 |
2003年 | 43篇 |
2002年 | 38篇 |
2001年 | 34篇 |
2000年 | 36篇 |
1999年 | 33篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1994年 | 2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1060条查询结果,搜索用时 9 毫秒
101.
A 19-mo-old female captive white-tailed deer in a public wild animal park in Richmond (Virginia, USA) was necropsied and evaluated histologically following spontaneous death after a 1 wk period of lethargy in a captive herd of 22 deer. An acute necrotizing pneumonia was associated with intraendothelial protozoal schizonts that were identified immunohistochemically as Sarcocystis spp. This is the first confirmed report of acute sarcocystosis in a wild ruminant. 相似文献
102.
Lehmann T Blackston CR Parmley SF Remington JS Dubey JP 《The Journal of parasitology》2000,86(5):960-971
Molecular characterization of Toxoplasma gondii isolates is central for understanding differences in disease transmission and manifestations. Only 3 subgroups (lineages) have been discerned with subtle within-lineage variation, permitting low-resolution classification of isolates. Because proteins, coding sequences, and especially antigen-coding genes have been used extensively in previous studies, we focused on sequence variation in introns of housekeeping genes, which may be more informative for phylogenetic analysis because they evolve under lower selection. We compared sequence variation in introns of 5 housekeeping genes with 2 antigen-coding genes. Introns of housekeeping genes were slightly more polymorphic than coding and noncoding regions of antigen-coding genes and only the former showed intralineage variation. Intragenic linkage disequilibrium was complete, but intergenic linkage, although highly significant, was incomplete, suggesting that genes are partially uncoupled. Six of 7 substitutions found within the region coding for the tachyzoite surface antigen, SAG2, were nonsynonymous, indicating that diversifying selection acts on this locus. Typing isolates on the basis of housekeeping and antigen-coding genes was consistent, but the phylogenetic relationships among the resulting groups was inconsistent. A cougar isolate typed as lineage II using a restriction fragment length polymorphism assay possessed multiple unique polymorphisms, suggesting that it represents a new lineage. We concluded that introns of housekeeping genes are preferred markers for phylogenetic study, and that multilocus genotyping is preferred for typing parasites, especially from feral or unstudied environments. 相似文献
103.
Deciphering the code that determines the three-dimensional structure of proteins and the ability to predict the final folded form of a protein is still elusive to molecular biophysists. In the case of several proteins a similar tertiary structure is not accompanied by any significant sequence similarity. The question now remains whether a code beyond the genetic code that describes the arrangement of the amino acid within a three dimensional protein structure. The available data undoubtedly demonstrates that the redundancy of this code must be tremendous. Several techniques such as nuclear magnetic resonance spectroscopy and laser detection techniques, coupled with fast initiation of the folding reaction, can now probe the folding events in milliseconds or even faster and provide highly relevant information. The thermodynamic analysis of the folding process and of kinetic intermediates opens whole new avenue of understanding. Breaking the protein folding code would enable scientists to look at a gene whose function is unknown and predict the three-dimensional structure of the protein it encodes. This would give them a very good idea of what the gene does. In this review we hope to bring together the information available about protein folding with particular emphasis on folding intermediate(s). Additionally, the practical consequences of the solution of the protein folding problem in medicine and biotechnology are also discussed. 相似文献
104.
105.
Ananth Kumar Kammalla Mohan Kumar Ramasamy Jyothi Inampudi Govind Prasad Dubey Aruna Agrawal Ilango Kaliappan 《AAPS PharmSciTech》2015,16(2):250-258
The US patented polyherbal formulation for the prevention and management of type II diabetes and its vascular complications was used for the present study. The xanthone glycoside mangiferin is one of the major effector constituents in the Salacia species with potential anti-diabetic activity. The pharmacokinetic differences of mangiferin following oral administration of pure mangiferin and polyherbal formulation containing Salacia species were studied with approximately the same dose 30 mg/kg mangiferin and its distribution among the major tissue in Wistar rats. Plasma samples were collected at different time points (15, 30, 60, 120, 180, 240, 360, 480, 600, 1,440, 2,160, and 2880 min) and subsequently analyzed using a validated simple and rapid LC-MS method. Plasma concentration versus time profiles were explored by non-compartmental analysis. Mangiferin plasma exposure was significantly increased when administered from formulation compared to the standard mangiferin. Mangiferin resided significantly longer in the body (last mean residence time (MRTlast)) when given in the form of the formulation (3.65 h). Cmax values of formulation (44.16 μg/mL) administration were elevated when compared to equivalent dose of the pure mangiferin (15.23 μg/mL). Tissue distribution study of mangiferin from polyherbal formulation was also studied. In conclusion, the exposure of mangiferin is enhanced after formulation and administration and could result in superior efficacy of polyherbal formulation when compared to an equivalent dose of mangiferin. The results indicate that the reason which delays the elimination of mangiferin and enhances its bioavailability might the interactions of the some other constituents present in the polyherbal formulation. Distribution study results indicate that mangiferin was extensively bound to the various tissues like the small intestine, heart, kidney, spleen, and liver except brain tissue.
Electronic supplementary material
The online version of this article (doi:10.1208/s12249-014-0206-8) contains supplementary material, which is available to authorized users.KEY WORDS: bioavailability, mangiferin, pharmacokinetics, polyherbal formulation, tissue distribution 相似文献106.
107.
108.
The prevalence of antibodies to Toxoplasma gondii was determined in sera from 106 domestic cats from St. Kitts, West Indies. Using a modified agglutination test, antibodies to this parasite were found in 90 (84.9%) of the cats, with titers of 1:20 in 23 cats, 1:40 in 34 cats, 1:80 in 18 cats, 1:160 in 2 cats, 1:320 in 1 cat, and 1:1,280 or higher in 11 cats. This is the first report of the prevalence of T. gondii infections in cats on St. Kitts and suggests widespread contamination of the environment with oocysts. 相似文献
109.
R. K. Dubey Rajesh Kumar Jaya N. K. Dubey 《World journal of microbiology & biotechnology》2007,23(4):467-473
Essential oils extracted from 17 higher plants belonging to different families were screened against Botryodiplodia theobromae and Colletotrichum gloeosporioides causing stem end rot disease and anthracnose disease in mango respectively. The essential oil of Eupatorium cannabinum was found to be fungitoxic in nature against both the mango-rotting fungi. Eupatorium oil was standardized through physico-chemical and fungitoxic properties. Gas Liquid Chromatography (GLC) analysis of the
oil led to the identification of 16 components, which represented 77.97% of the oil. Germacrene D (16.11%) was found to be
the major component. The oil showed a broad fungitoxic spectrum and was recorded to be more efficient than some synthetic
fungicides. The oil also showed an inhibitory effect on pectinase and cellulase enzymes. The oil enhanced the shelf life of
mango fruits by protecting from fungal rotting when tested as a fumigant. The LD50 of Eupatorium oil was found to be 22.01 ml/kg body weight on mammalian mice. 相似文献
110.
Red mud is a bauxite residue, a by-product of the Bayer process for extraction of alumina from bauxite ore. It is highly alkaline in nature and contains heavy metal oxides and a variety of minor trace elements. Its disposal is the paramount environmental issue in alumina refining. Establishment of vegetation on red mud dumping sites is difficult because of alkaline pH and high concentrations of soluble ions and toxic compounds. The bioremediation of red mud seems to be a realistically convenient way for environmentally safe disposal of this industrial residue. The present study specifically deals with the utilization of cyanobacteria to bioremediate red mud. Being predominantly a nitrogen-fixing photosynthetic microorganism, it has considerable potential for bioremediation of bauxite residue. As a prelude step, four cyanobacterial species, viz. Oscillatoria sp., Lyngbya sp., Phormidium sp., and Microcystis sp. were selected to study their capability to grow on red mud–amended medium. The results indicate that Oscillatoria and Phormidium performed well on red mud–amended medium, followed by Lyngbya. Growth of Microcystis was inhibited significantly even at lower concentrations of red mud amendments. These findings point out the potential of these microorganisms, to be utilized as active biological agents for bioremediation of red mud. 相似文献