全文获取类型
收费全文 | 34895篇 |
免费 | 16194篇 |
国内免费 | 1068篇 |
出版年
2024年 | 12篇 |
2023年 | 124篇 |
2022年 | 361篇 |
2021年 | 897篇 |
2020年 | 2511篇 |
2019年 | 4064篇 |
2018年 | 4160篇 |
2017年 | 4345篇 |
2016年 | 4454篇 |
2015年 | 4551篇 |
2014年 | 4318篇 |
2013年 | 4745篇 |
2012年 | 2591篇 |
2011年 | 2215篇 |
2010年 | 3476篇 |
2009年 | 2155篇 |
2008年 | 1197篇 |
2007年 | 734篇 |
2006年 | 685篇 |
2005年 | 637篇 |
2004年 | 625篇 |
2003年 | 631篇 |
2002年 | 618篇 |
2001年 | 488篇 |
2000年 | 336篇 |
1999年 | 315篇 |
1998年 | 117篇 |
1997年 | 99篇 |
1996年 | 97篇 |
1995年 | 100篇 |
1994年 | 76篇 |
1993年 | 60篇 |
1992年 | 60篇 |
1991年 | 49篇 |
1990年 | 43篇 |
1989年 | 44篇 |
1988年 | 27篇 |
1987年 | 21篇 |
1986年 | 22篇 |
1985年 | 9篇 |
1984年 | 13篇 |
1983年 | 14篇 |
1982年 | 13篇 |
1981年 | 11篇 |
1980年 | 6篇 |
1979年 | 7篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1974年 | 2篇 |
1972年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
991.
992.
993.
M.N.A. Amal M. Zamri‐Saad A. Siti‐Zahrah A.R. Zulkafli M. Nur‐Nazifah 《Journal of applied microbiology》2013,115(1):20-29
Aims
The aim of this study was to characterize Streptococcus agalactiae strains that were isolated from fishes in Malaysia using random amplified polymorphic DNA (RAPD) and repetitive extragenic palindromic PCR (REP‐PCR) techniques.Methods and Results
A total of 181 strains of Strep. agalactiae isolated from red hybrid tilapia (Oreochromis sp.) and golden pompano (Trachinotus blochii) were characterized using RAPD and REP‐PCR techniques. Both the fingerprinting techniques generated reproducible band patterns, differing in the number and molecular mass amplicons. The RAPD technique displayed greater discriminatory power by its production of more complex binding pattern and divided all the strains into 13 groups, compared to 9 by REP‐PCR technique. Both techniques showed the availability to differentiate the genetic profiles of the strains according to their geographical location of origin. Three strains of Strep. agalactiae that were recovered from golden pompano showed a genetic dissimilarity from the strains isolated from red hybrid tilapia, while the strain of ATCC 27956 that recovered from bovine displayed a unique profile for both methods.Conclusions
Both techniques possess excellent discriminative capabilities and can be used as a rapid means of comparing Strep. agalactiae strains for future epidemiological investigation.Significance and Impact of the Study
Framework as the guideline in traceability of this disease and in the search for potential local vaccine candidates for streptococcosis in this country. 相似文献994.
995.
996.
997.
M.J. Torres A. Hidalgo‐García E.J. Bedmar M.J. Delgado 《Journal of applied microbiology》2013,114(6):1772-1781
Aim
In this work, phenotypic analyses of a Ensifer meliloti fixN1 mutant under free‐living and symbiotic conditions have been carried out.Methods and Results
Ensifer meliloti fixN1 mutant showed a defect in growth as well as in TMPD‐dependent oxidase activity when cells were incubated under micro‐oxic conditions. Furthermore, haem c staining analyses of a fixN1 and a fixP1 mutant identified two membrane‐bound c‐type cytochromes of 27 and 32 kDa, present in microaerobically grown cells and in bacteroids, as the FixO and FixP components of the E. meliloti cbb3 oxidase. Under symbiotic conditions, fixN1 mutant showed a clear nitrogen fixation defect in alfalfa plants that were grown in an N‐free nutrient solution during 3 weeks. However, in plants grown for a longer period, fixNOQP1 copy was not indispensable for symbiotic nitrogen fixation.Conclusions
The copy 1 of the fixNOQP operon is involved in E. meliloti respiration and growth under micro‐oxic conditions as well as in the expression of the FixO and FixP components of the cbb3 oxidase present in free‐living microaerobic cultures and in bacteroids. This copy is important for nitrogen fixation during the early steps of the symbiosis.Significance and Impact of the Study
It is the first time that a functional analysis of the E. meliloti copy 1 of the fixNOQP operon is performed. In this work, the cytochromes c that constitute the cbb3 oxidase operating in free‐living micro‐oxic cultures and in bacteroids of E. meliloti have been identified. 相似文献998.
999.
1000.
Min Wu Qi Shen Yong Yang Sheng Zhang Wen Qu Jing Chen Hongying Sun Shuqing Chen 《Journal of industrial microbiology & biotechnology》2013,40(6):589-599
Human serum albumin (HSA) and human parathyroid hormone (1-34) [PTH (1-34)] fusion protein [HSA/PTH (1-34)] is a promising long-acting form of PTH (1-34) for osteoporosis treatment. Secretory expression of intact HSA/PTH (1-34) in Pichia pastoris GS115 was accompanied by two degradation fragments, with molecular weights around 66 kDa, in addition to the well-known ~45 kDa HSA-truncated fragment, resulting in a low yield of intact protein. In this study, two internal cleavage sites were identified in the PTH (1-34) portion of the fusion protein by Western Blot analysis. To minimize proteolytic cleavages, several protease genes including PEP4 (encoding proteinase A), PRB1 (proteinase B) and seven YPSs genes (yapsin family members) were knocked out respectively by disruption of the individual genes and the selective combinations. Reduced degradation was observed by single disruption of either PEP4 gene or YPS1 gene, and the lowest level of degradation was observed in a pep4△yps1△ double disruptant. After 72 h of induction, more than 80 % of the HSA/PTH (1-34) secreted by the pep4△yps1△ double disruptant remained intact, in comparison to only 30 % with the wild-type strain. 相似文献