全文获取类型
收费全文 | 989篇 |
免费 | 49篇 |
国内免费 | 1篇 |
专业分类
1039篇 |
出版年
2023年 | 5篇 |
2022年 | 17篇 |
2021年 | 25篇 |
2020年 | 16篇 |
2019年 | 12篇 |
2018年 | 11篇 |
2017年 | 13篇 |
2016年 | 23篇 |
2015年 | 35篇 |
2014年 | 50篇 |
2013年 | 72篇 |
2012年 | 83篇 |
2011年 | 75篇 |
2010年 | 50篇 |
2009年 | 31篇 |
2008年 | 40篇 |
2007年 | 55篇 |
2006年 | 40篇 |
2005年 | 50篇 |
2004年 | 44篇 |
2003年 | 51篇 |
2002年 | 26篇 |
2001年 | 7篇 |
2000年 | 8篇 |
1999年 | 9篇 |
1998年 | 10篇 |
1997年 | 6篇 |
1996年 | 7篇 |
1995年 | 9篇 |
1994年 | 8篇 |
1993年 | 4篇 |
1992年 | 9篇 |
1991年 | 7篇 |
1990年 | 13篇 |
1989年 | 11篇 |
1988年 | 9篇 |
1987年 | 10篇 |
1986年 | 6篇 |
1985年 | 5篇 |
1984年 | 13篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1976年 | 7篇 |
1973年 | 5篇 |
1970年 | 2篇 |
1966年 | 3篇 |
1963年 | 3篇 |
排序方式: 共有1039条查询结果,搜索用时 15 毫秒
71.
72.
P. Rama Mohan Reddy M.V. Swamy G. Seenayya 《World journal of microbiology & biotechnology》1998,14(1):89-94
Thermostable -amylase and pullulanase, secreted by the thermophilic anaerobic bacterium Clostridium thermosulfurogenes strain SV2, were purified by salting out with ammonium sulphate, DEAE-cellulose column chromatography, and gel filtration using Sephadex G-200. Maltose was identified as a major hydrolysis product of starch by -amylase, and maltotriose was identified as a major hydrolysis product of pullulan by pullulanase. The molecular masses of native -amylase and pullulanase were determined to be 180 and 100 kDa by gel filtration, and 210 and 80 kDa by SDS–PAGE, respectively. The temperature optima of purified -amylase and pullulanase were 70 and 75°C, respectively, and both enzymes were completely stable at 70°C for 2h. The presence of starch further increased the stability of both the enzymes to 80°C and both displayed a pH activity optimum of 6.0. The starch hydrolysis products formed by -amylase action had -anomeric form. 相似文献
73.
Wilson’s disease is an autosomal recessive disorder of copper accumulation in various organs, with most common clinical manifestations
such as hepatic, neurological, and renal dysfunctions. Serum copper and ceruloplasmin in Wilson’s disease were significantly
lower as compared to normals, controls, and relatives of Wilson’s disease patients, whereas marked hypercupriuria (145 ± 7
μg/24 h) was observed in Wilson’s children only. A good correlation (r = 0.92) was found between non-ceruloplasmin-bound copper and 24-h urinary copper excretion in Wilson’s disease patients.
Further, copper studies among the different phenotypes of Wilson’s disease revealed substantially low serum ceruloplasmin
and a marked hypercupriuria in Wilson’s disease children associated with renal tubular acidosis as compared to the patients
with either hepatological or neurological manifestations. Serum ceruloplasmin levels in 14 patients of Wilson’s disease were
between 14 and 20 mg/dL. These patients of Wilson’s disease were confirmed by measuring liver biopsy copper, which was about
nine times higher than normal hepatic copper content. During the family screening by copper studies, four asymptomatic siblings
were diagnosed for Wilson’s disease. These subjects were then started on D-penicillamine therapy because presymptomatic treatment
prevents progression of the disease complications. 相似文献
74.
75.
Rama Kandasamy Meeru Gurung Anushil Thapa Susan Ndimah Neelam Adhikari David R. Murdoch Dominic F. Kelly Denise E. Waldron Katherine A. Gould Stephen Thorson Shrijana Shrestha Jason Hinds Andrew J. Pollard 《PloS one》2015,10(2)
Invasive pneumococcal disease is one of the major causes of death in young children in resource poor countries. Nasopharyngeal carriage studies provide insight into the local prevalence of circulating pneumococcal serotypes. There are very few data on the concurrent carriage of multiple pneumococcal serotypes. This study aimed to identify the prevalence and serotype distribution of pneumococci carried in the nasopharynx of young healthy Nepalese children prior to the introduction of a pneumococcal conjugate vaccine using a microarray-based molecular serotyping method capable of detecting multi-serotype carriage. We conducted a cross-sectional study of healthy children aged 6 weeks to 24 months from the Kathmandu Valley, Nepal between May and October 2012. Nasopharyngeal swabs were frozen and subsequently plated on selective culture media. DNA extracts of plate sweeps of pneumococcal colonies from these cultures were analysed using a molecular serotyping microarray capable of detecting relative abundance of multiple pneumococcal serotypes. 600 children were enrolled into the study: 199 aged 6 weeks to <6 months, 202 aged 6 months to < 12 months, and 199 aged 12 month to 24 months. Typeable pneumococci were identified in 297/600 (49·5%) of samples with more than one serotype being found in 67/297 (20·2%) of these samples. The serotypes covered by the thirteen-valent pneumococcal conjugate vaccine were identified in 44·4% of samples containing typeable pneumococci. Application of a molecular serotyping approach to identification of multiple pneumococcal carriage demonstrates a substantial prevalence of co-colonisation. Continued surveillance utilising this approach following the introduction of routine use of pneumococcal conjugate vaccinates in infants will provide a more accurate understanding of vaccine efficacy against carriage and a better understanding of the dynamics of subsequent serotype and genotype replacement. 相似文献
76.
Genetic diversity in Puerto Rico and its implications for the peopling of the Island and the West Indies 下载免费PDF全文
Miguel G. Vilar Carlalynne Melendez Akiva B. Sanders Akshay Walia Jill B. Gaieski Amanda C. Owings Theodore G. Schurr The Genographic Consortium 《American journal of physical anthropology》2014,155(3):352-368
Puerto Rico and the surrounding islands rest on the eastern fringe of the Caribbean's Greater Antilles, located less than 100 miles northwest of the Lesser Antilles. Puerto Ricans are genetic descendants of pre‐Columbian peoples, as well as peoples of European and African descent through 500 years of migration to the island. To infer these patterns of pre‐Columbian and historic peopling of the Caribbean, we characterized genetic diversity in 326 individuals from the southeastern region of Puerto Rico and the island municipality of Vieques. We sequenced the mitochondrial DNA (mtDNA) control region of all of the samples and the complete mitogenomes of 12 of them to infer their putative place of origin. In addition, we genotyped 121 male samples for 25 Y‐chromosome single nucleotide polymorphism and 17 STR loci. Approximately 60% of the participants had indigenous mtDNA haplotypes (mostly from haplogroups A2 and C1), while 25% had African and 15% European haplotypes. Three A2 sublineages were unique to the Greater Antilles, one of which was similar to Mesoamerican types, while C1b haplogroups showed links to South America, suggesting that people reached the island from the two distinct continental source areas. However, none of the male participants had indigenous Y‐chromosomes, with 85% of them instead being European/Mediterranean and 15% sub‐Saharan African in origin. West Eurasian Y‐chromosome short tandem repeat haplotypes were quite diverse and showed similarities to those observed in southern Europe, North Africa and the Middle East. These results attest to the distinct, yet equally complex, pasts for the male and female ancestors of modern day Puerto Ricans. Am J Phys Anthropol 155:352–368, 2014. © 2014 Wiley Periodicals, Inc. 相似文献
77.
78.
79.
Kirti Gupta Ritambhra Nada Kusum Joshi Minakshi Rohilla Rama Walia 《Mycopathologia》2010,170(5):357-360
Mucormycosis is an uncommon opportunistic infection by filamentous fungi that usually develops in immmunocompromised patients.
Most individuals have an underlying systemic disease, such as diabetes mellitus, malignancy, uraemia, burns, renal transplant
recipients and those on corticosteroid and immunosuppressive therapy. Many cases of primary renal zygomycosis with lungs serving
as the portal of entry have been reported from this region. We describe two autopsy cases of renal zygomycosis where bladder
appeared to be the portal of entry for the fungus. 相似文献
80.
Fernando Rodríguez‐Serrano Pablo Álvarez Octavio Caba Manuel Picón Juan A. Marchal Macarena Perán José Prados Consolación Melguizo Ana R. Rama Houria Boulaiz Antonia Aránega 《Cell biology international》2010,34(9):917-924
Adult stem cells are becoming the best option for regenerative medicine because they have low tumourigenic potential and permit autologous transplantation, even without in vitro culture. Our objectives were to evaluate the effects of exogenous nucleosides on the proliferation of hASCs (human adipose‐derived stem cells), with or without co‐treatment with 5‐aza (5‐azacytidine), and to analyse the expression of lamin A/C during cardiomyocyte differentiation of these cells. We isolated hASCs from human lipoaspirates that were positive for mesenchymal stem cell markers. We found that 5‐aza induces a dose‐dependent inhibition of hASC proliferation [IC50 (inhibitory concentration 50): 5.37 μM], whereas exogenous nucleosides significantly promote the proliferation of hASCs and partially revert the antiproliferative effect of the drug. Multipotentiality of isolated hASCs was confirmed by adipogenic, osteogenic and cardiomyogenic induction. 5‐Aza‐induced cells expressed cardiac troponins I and T and myosin light chain 2, myocardial markers that were directly correlated with lamin A/C expression. Our results support the importance of the nucleoside supplementation of media to improve conditions for the expansion and maintenance of hASCs in culture. In addition, the quantification of lamin A/C expression appears to be a good marker for the characterization of cardiomyocyte differentiation of stem cells that has rarely been used. 相似文献