全文获取类型
收费全文 | 1518篇 |
免费 | 88篇 |
国内免费 | 2篇 |
专业分类
1608篇 |
出版年
2024年 | 3篇 |
2023年 | 14篇 |
2022年 | 25篇 |
2021年 | 48篇 |
2020年 | 20篇 |
2019年 | 24篇 |
2018年 | 41篇 |
2017年 | 47篇 |
2016年 | 55篇 |
2015年 | 68篇 |
2014年 | 86篇 |
2013年 | 121篇 |
2012年 | 138篇 |
2011年 | 143篇 |
2010年 | 63篇 |
2009年 | 67篇 |
2008年 | 97篇 |
2007年 | 75篇 |
2006年 | 78篇 |
2005年 | 75篇 |
2004年 | 66篇 |
2003年 | 59篇 |
2002年 | 38篇 |
2001年 | 16篇 |
2000年 | 20篇 |
1999年 | 17篇 |
1998年 | 9篇 |
1997年 | 10篇 |
1996年 | 5篇 |
1995年 | 8篇 |
1994年 | 3篇 |
1993年 | 8篇 |
1992年 | 5篇 |
1991年 | 13篇 |
1990年 | 5篇 |
1989年 | 10篇 |
1988年 | 1篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1974年 | 2篇 |
1972年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有1608条查询结果,搜索用时 15 毫秒
981.
Srinivas Talluri 《Flexible Services and Manufacturing Journal》2000,12(4):291-304
Benchmarking assists businesses in identifying potential targets for improvement. It is the initial step a firm must undertake before planning and implementing reengineering methods to achieve higher productivity. Although several benchmarking methods have been proposed in the literature, research in this area lacks rigorous analytical tools for effective benchmarking. A benchmarking method must simultaneously analyze and integrate several key performance measures of business processes in identifying best practices. This is easier said than done because it is by no means a trivial task to blend multidimensional information in a useful and effective manner. This article proposes a benchmarking method that simultaneously considers multiple measures and aids in business process reengineering efforts of organizations. The proposed technique is based on a combination of multifactor productivity analysis, game theory, and clustering methods. These models are tested on a previously reported data set of manufacturing processes. Our results provide some very interesting insights into benchmarking practices, which when followed by firms will help in successful business process reengineering efforts. 相似文献
982.
We present a comprehensive radiation hybrid map of the bovine X chromosome (Chr) containing 20 new markers, including both
microsatellites and expressed genes. This study was conducted with a 5000-rad whole genome RH cell panel consisting of 90
hybrid cell lines. Retention frequencies of individual markers range from 7.8% for XIST to 31.1% for TGLA325. Statistical
analysis with RHMAPPER placed all the loci into five linkage groups under a LOD score criterion of 6.0. These groups could
be oriented relative to each other because they included multiple microsatellite loci from the consensus linkage map of the
X Chr. Markers included in both this RH map and the bovine cytogenetic map were in a consistent order. The comparative bovine–human
map thus generated consists of five blocks of genes, the order of which is conserved, although in the opposite direction when
presented as ideograms with p and q arms. Inversions of three blocks account for the difference in gene order across the entirety
of the two X Chrs. 相似文献
983.
984.
S.N. Suryawanshi Avinash Tiwari Naveen Chandra Suman Gupta 《Bioorganic & medicinal chemistry letters》2012,22(21):6559-6562
Novel isoxazole containing heteroretinoid (4) and its amide derivatives (5a–j) have been synthesized and evaluated for their in vivo antileishmanial activity against Leishmania donovani in hamsters. Compounds 3, 5a, 5d, 5k and 5l inhibited 70–76% parasite growth at 50 mg kg?1 × 5 days. The present study has helped us in identifying a new lead that could be exploited as a potential antileishmanial agent. 相似文献
985.
Sasmal S Balaji G Kanna Reddy HR Balasubrahmanyam D Srinivas G Kyasa S Sasmal PK Khanna I Talwar R Suresh J Jadhav VP Muzeeb S Shashikumar D Harinder Reddy K Sebastian VJ Frimurer TM Rist Ø Elster L Högberg T 《Bioorganic & medicinal chemistry letters》2012,22(9):3157-3162
Melanin concentrating hormone (MCH) is an important mediator of energy homeostasis and plays a role in metabolic and CNS disorders. The modeling-supported design, synthesis and multi-parameter optimization (biological activity, solubility, metabolic stability, hERG) of novel quinazoline derivatives as MCHR1 antagonists are described. The in vivo proof of principle for weight loss with a lead compound from this series is exemplified. Clusters of refined hMCHR1 homology models derived from the X-ray structure of the β2-adrenergic receptor, including extracellular loops, were developed and used to guide the design. 相似文献
986.
Petrie JR Shrestha P Belide S Mansour MP Liu Q Horne J Nichols PD Singh SP 《Transgenic research》2012,21(1):139-147
We describe a transgenic microalgal Δ9-elongase pathway transformed in both Brassica napus and Arabidopsis thaliana seed resulting in the production of arachidonic acid (ARA). This pathway is noteworthy for both the production of ARA in
seed tissue and the low levels of intermediate C20 fatty acids that accumulate. We also demonstrate that the arachidonic acid
is naturally enriched at the sn2 position in triacylglycerol. This is the first report of ARA production by the Δ9-elongase pathway in an oilseed. 相似文献
987.
988.
Alex Levin Mieszko Lis Yann Ponty Charles W. O’Donnell Srinivas Devadas Bonnie Berger Jér?me Waldispühl 《Nucleic acids research》2012,40(20):10041-10052
The development of algorithms for designing artificial RNA sequences that fold into specific secondary structures has many potential biomedical and synthetic biology applications. To date, this problem remains computationally difficult, and current strategies to address it resort to heuristics and stochastic search techniques. The most popular methods consist of two steps: First a random seed sequence is generated; next, this seed is progressively modified (i.e. mutated) to adopt the desired folding properties. Although computationally inexpensive, this approach raises several questions such as (i) the influence of the seed; and (ii) the efficiency of single-path directed searches that may be affected by energy barriers in the mutational landscape. In this article, we present RNA-ensign, a novel paradigm for RNA design. Instead of taking a progressive adaptive walk driven by local search criteria, we use an efficient global sampling algorithm to examine large regions of the mutational landscape under structural and thermodynamical constraints until a solution is found. When considering the influence of the seeds and the target secondary structures, our results show that, compared to single-path directed searches, our approach is more robust, succeeds more often and generates more thermodynamically stable sequences. An ensemble approach to RNA design is thus well worth pursuing as a complement to existing approaches. RNA-ensign is available at http://csb.cs.mcgill.ca/RNAensign. 相似文献
989.
Synthesis of C-8 methanesulphonate substituted pyrrolobenzodiazepines as potential antitumour agents
Kamal A Ramulu P Srinivas O Ramesh G 《Bioorganic & medicinal chemistry letters》2003,13(20):3517-3519
The facile synthesis of C-8 methanesulphonate substituted pyrrolobenzodiazepines is described. These have been prepared by linking the methanesulphonate at C-8 position with alkanol spacer and their in vitro cytotoxicity have been described. 相似文献
990.
A radiation hybrid (RH) map of the equine X chromosome (ECAX) was obtained using the recently produced 5000(rad) horse x hamster hybrid panel. The map comprises 34 markers (16 genes and 18 microsatellites) and spans a total of 676 cR(5000), covering almost the entire length of ECAX. Cytogenetic alignment of the RH map was improved by fluorescent in situ hybridization mapping of six of the markers. The map integrates and refines the currently available genetic linkage, syntenic, and cytogenetic maps, and adds new loci. Comparison of the physical location of the 16 genes mapped in this study with the human genome reveals similarity in the order of the genes along the entire length of the two X chromosomes. This degree of gene order conservation across evolutionarily distantly related species has up to now been reported only between human and cat. The ECAX RH map provides a framework for the generation of a high-density map for this chromosome. The map will serve as an important tool for positional cloning of X-linked diseases/conditions in the horse. 相似文献