全文获取类型
收费全文 | 3628篇 |
免费 | 301篇 |
国内免费 | 34篇 |
出版年
2023年 | 18篇 |
2022年 | 42篇 |
2021年 | 64篇 |
2020年 | 45篇 |
2019年 | 45篇 |
2018年 | 60篇 |
2017年 | 54篇 |
2016年 | 95篇 |
2015年 | 155篇 |
2014年 | 175篇 |
2013年 | 230篇 |
2012年 | 265篇 |
2011年 | 284篇 |
2010年 | 199篇 |
2009年 | 198篇 |
2008年 | 256篇 |
2007年 | 246篇 |
2006年 | 226篇 |
2005年 | 211篇 |
2004年 | 211篇 |
2003年 | 176篇 |
2002年 | 186篇 |
2001年 | 64篇 |
2000年 | 34篇 |
1999年 | 40篇 |
1998年 | 49篇 |
1997年 | 35篇 |
1996年 | 24篇 |
1995年 | 28篇 |
1994年 | 21篇 |
1993年 | 15篇 |
1992年 | 14篇 |
1991年 | 12篇 |
1990年 | 13篇 |
1989年 | 10篇 |
1988年 | 13篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 10篇 |
1984年 | 6篇 |
1983年 | 13篇 |
1982年 | 15篇 |
1981年 | 14篇 |
1980年 | 9篇 |
1979年 | 4篇 |
1978年 | 10篇 |
1977年 | 10篇 |
1976年 | 4篇 |
1955年 | 3篇 |
1949年 | 5篇 |
排序方式: 共有3963条查询结果,搜索用时 15 毫秒
991.
Smallpox was eradicated without an adequate understanding of how vaccination induced protection. In response to possible bioterrorism with smallpox, the UK government vaccinated approximately 300 health care workers with vaccinia virus (VACV) strain Lister. Antibody responses were analyzed using ELISA for multiple surface antigens of the extracellular enveloped virus (EEV) and the intracellular mature virus (IMV), plaque reduction neutralization and a fluorescence-based flow cytometric neutralization assay. Antibody depletion experiments showed that the EEV surface protein B5 is the only target responsible for EEV neutralization in vaccinated humans, whereas multiple IMV surface proteins, including A27 and H3, are targets for IMV-neutralizing antibodies. These data suggest that it would be unwise to exclude the B5 protein from a future smallpox vaccine. Repeated vaccination provided significantly higher B5-specific and thus EEV-neutralizing antibody responses. These data provide a benchmark against which new, safer smallpox vaccines and residual immunity can be compared. 相似文献
992.
The MicroArray Quality Control (MAQC) project shows inter- and intraplatform reproducibility of gene expression measurements 总被引:2,自引:0,他引:2
MAQC Consortium Shi L Reid LH Jones WD Shippy R Warrington JA Baker SC Collins PJ de Longueville F Kawasaki ES Lee KY Luo Y Sun YA Willey JC Setterquist RA Fischer GM Tong W Dragan YP Dix DJ Frueh FW Goodsaid FM Herman D Jensen RV Johnson CD Lobenhofer EK Puri RK Schrf U Thierry-Mieg J Wang C Wilson M Wolber PK Zhang L Amur S Bao W Barbacioru CC Lucas AB Bertholet V Boysen C Bromley B Brown D Brunner A Canales R Cao XM Cebula TA Chen JJ Cheng J Chu TM Chudin E Corson J Corton JC Croner LJ 《Nature biotechnology》2006,24(9):1151-1161
Over the last decade, the introduction of microarray technology has had a profound impact on gene expression research. The publication of studies with dissimilar or altogether contradictory results, obtained using different microarray platforms to analyze identical RNA samples, has raised concerns about the reliability of this technology. The MicroArray Quality Control (MAQC) project was initiated to address these concerns, as well as other performance and data analysis issues. Expression data on four titration pools from two distinct reference RNA samples were generated at multiple test sites using a variety of microarray-based and alternative technology platforms. Here we describe the experimental design and probe mapping efforts behind the MAQC project. We show intraplatform consistency across test sites as well as a high level of interplatform concordance in terms of genes identified as differentially expressed. This study provides a resource that represents an important first step toward establishing a framework for the use of microarrays in clinical and regulatory settings. 相似文献
993.
994.
Shippy R Fulmer-Smentek S Jensen RV Jones WD Wolber PK Johnson CD Pine PS Boysen C Guo X Chudin E Sun YA Willey JC Thierry-Mieg J Thierry-Mieg D Setterquist RA Wilson M Lucas AB Novoradovskaya N Papallo A Turpaz Y Baker SC Warrington JA Shi L Herman D 《Nature biotechnology》2006,24(9):1123-1131
We have assessed the utility of RNA titration samples for evaluating microarray platform performance and the impact of different normalization methods on the results obtained. As part of the MicroArray Quality Control project, we investigated the performance of five commercial microarray platforms using two independent RNA samples and two titration mixtures of these samples. Focusing on 12,091 genes common across all platforms, we determined the ability of each platform to detect the correct titration response across the samples. Global deviations from the response predicted by the titration ratios were observed. These differences could be explained by variations in relative amounts of messenger RNA as a fraction of total RNA between the two independent samples. Overall, both the qualitative and quantitative correspondence across platforms was high. In summary, titration samples may be regarded as a valuable tool, not only for assessing microarray platform performance and different analysis methods, but also for determining some underlying biological features of the samples. 相似文献
995.
996.
Rodriguez-Viciana P Oses-Prieto J Burlingame A Fried M McCormick F 《Molecular cell》2006,22(2):217-230
Ras family GTPases (RFGs) are known to share many regulatory and effector proteins. How signaling and biological specificity is achieved is poorly understood. Using a proteomics approach, we have identified a complex comprised of Shoc2/Sur-8 and the catalytic subunit of protein phosphatase 1 (PP1c) as a highly specific M-Ras effector. M-Ras targets Shoc2-PP1c to stimulate Raf activity by dephosphorylating the S259 inhibitory site of Raf proteins bound to other molecules of M-Ras or Ras. Therefore, distinct RFGs, through independent effectors, can regulate different steps in the activation of Raf kinases. Shoc2 function is essential for activation of the MAPK pathway by growth factors. Furthermore, in tumor cells with Ras gene mutations, inhibition of Shoc2 expression inhibits MAPK, but not PI3K activity. We propose that the Shoc2-PP1c holoenzyme provides an attractive therapeutic target for inhibition of the MAPK pathway in cancer. 相似文献
997.
Significant improvements in our knowledge of tumor immunology have resulted in more sophisticated vaccine approaches for the treatment of cancer. However, research into biomarkers that correlate with the clinical outcome of immunotherapy has lagged behind vaccine development. To this extent, very few immunological or other markers exist that can be used in clinical trials for immunotherapy. In this review, we discuss the current status of biomarker development specifically for the monitoring and development of cancer vaccines. This includes immunological biomarkers (measurement of T-cell and cytokine responses), autoimmunity as a correlate for treatment outcome, and the possible development of multiple biomarkers using high-throughput proteomics technologies. The generation of such biomarkers will allow us to make clinical decisions about patient treatment at an earlier stage and should aid in shortening the development time for vaccines. 相似文献
998.
The relative importance of monkey beetles (Hopliini, Scarabeidae) as pollinators of Asteraceae and Aizoaceae in the Succulent Karoo as well as the influence of livestock grazing on their abundance and diversity was investigated. Hopliine beetles proved to be the, or among the, most abundant flower visitors of 12 investigated plant species. However, during single flower observations at three Aizoaceae species, bees (Apoidea), bee flies (Bombyliidae) and pollen wasps (Masaridae) were the most frequent flower visitors. However, monkey beetles carried the highest Asteraceae and Aizoaceae pollen loads, and are therefore considered to play a vital role in the pollination of these two families. Abundance, species richness and diversity of Hopliini did not appear to be heavily affected by livestock grazing. Annual variation in the composition of monkey beetle populations was more dramatic. Still, some species showed higher abundances on heavily grazed rangeland while others only occurred under low grazing pressure. It is presumed that changes in the composition of the vegetation, especially the observed decrease of perennial plants in favour of annuals and geophytes (Todd and Hoffman 1999) could in turn affect the composition of monkey beetle assemblages. 相似文献
999.
I have become aware that uncertainty exists in some quartersover what is or is not acceptable for submission as an originalresearch paper to this and similar journals. It appears thatthe essential characteristics of such articles are not alwaysfully appreciated, suggesting pressure to lower the basic standardsthat prescribe the peer-reviewed research paper. This editorialmakes it clear that theAnnals of Botanystrongly resists suchpressures. It views the successful peer-reviewed paper as theprincipal hallmark of success for individual scientists andthe gold standard that defines tangible progressin science. I will not try to delineate all the features expectedof a satisfactory research paper but, instead, point to theparamount necessity of their being original works. Readers mustbe able to take it on trust that the contents of published papershave not been stolen from others or published in substantivemeasure elsewhere by the author. Protecting that trust is oneof the Journal's foremost concerns and it is no coincidencethat the opening sentence of our Instructions to Authorsbegins with the phrase Contributions must be original'.Some other journals also adopt similar wording and authors shouldtake note of this most basic requirement. It underpins the credibilityand good standing of the standard peer-reviewed research paper.There is some risk of ambiguity concerning what is meant byoriginal when an author writes on a similar subjectin both a refereed journal and in a non-refereed format suchas a chapter in a book. While this practice is entirely legitimate,the reader has the right to a scholarly reworking of ideas,substance and content in both cases. The reader is also entitledto expect appropriate cross-referencing between the two formsof communication and for the research paper to be recognizedas the primary source. Such cross-referencing is but a partof the larger requirement of being open about sources of knowledgeand about the influences that bear on the research being described.Scientific publishing of peer-reviewed science is serious workand theAnnals of Botanyendeavours to maintain the highest possiblestanding for its Original Articles. It takes promptpublic action whenever basic precepts essential to maintainingthis high standing are discovered to have been ignored by anyof its contributors.Copyright 1999 Annals of Botany Company 相似文献
1000.
Non-syndromic hearing loss associated with enlarged vestibular aqueduct is caused by PDS mutations 总被引:23,自引:0,他引:23
Enlarged vestibular aqueduct (EVA), known as the most common form of inner ear abnormality, has recently been of particular
genetic interest because this anomaly is inherited in a recessive manner. The locus for non-syndromic sensorineural hearing
loss with EVA has been mapped to the same chromosomal region, 7q31, as the Pendred syndrome locus. In the present study, seven
mutations in the PDS gene (PDS), the gene responsible for Pendred syndrome, have been found in families of non-syndromic sensorineural hearing loss with
EVA. One family is homozygous, three families are compound heterozygotes, and two families are heterozygous but with no other
mutation detected. The present results provide evidence that mutations in PDS cause both syndromic and non-syndromic hearing loss.
Received: 21 October 1998 / Accepted: 5 December 1998 相似文献