全文获取类型
收费全文 | 11828篇 |
免费 | 1339篇 |
国内免费 | 3篇 |
专业分类
13170篇 |
出版年
2022年 | 77篇 |
2021年 | 134篇 |
2020年 | 142篇 |
2019年 | 221篇 |
2018年 | 240篇 |
2017年 | 257篇 |
2016年 | 324篇 |
2015年 | 526篇 |
2014年 | 531篇 |
2013年 | 727篇 |
2012年 | 711篇 |
2011年 | 637篇 |
2010年 | 534篇 |
2009年 | 465篇 |
2008年 | 566篇 |
2007年 | 582篇 |
2006年 | 569篇 |
2005年 | 615篇 |
2004年 | 580篇 |
2003年 | 628篇 |
2002年 | 634篇 |
2001年 | 121篇 |
2000年 | 102篇 |
1999年 | 156篇 |
1998年 | 199篇 |
1997年 | 142篇 |
1996年 | 142篇 |
1995年 | 143篇 |
1994年 | 123篇 |
1993年 | 90篇 |
1992年 | 129篇 |
1991年 | 100篇 |
1990年 | 91篇 |
1989年 | 93篇 |
1988年 | 72篇 |
1987年 | 87篇 |
1986年 | 78篇 |
1985年 | 95篇 |
1984年 | 102篇 |
1983年 | 83篇 |
1982年 | 107篇 |
1981年 | 119篇 |
1980年 | 90篇 |
1979年 | 92篇 |
1978年 | 90篇 |
1977年 | 80篇 |
1976年 | 83篇 |
1975年 | 53篇 |
1974年 | 73篇 |
1973年 | 66篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
Monika Oláhová Wan Hee Yoon Kyle Thompson Sharayu Jangam Liliana Fernandez Jean M. Davidson Jennifer E. Kyle Megan E. Grove Dianna G. Fisk Jennefer N. Kohler Matthew Holmes Annika M. Dries Yong Huang Chunli Zhao Kévin Contrepois Zachary Zappala Laure Frésard Daryl Waggott Matthew T. Wheeler 《American journal of human genetics》2018,102(3):494-504
972.
Biosynthesis of abscisic acid in fungi: identification of a sesquiterpene cyclase as the key enzyme in Botrytis cinerea 下载免费PDF全文
Inmaculada Izquierdo‐Bueno Victoria E. González‐Rodríguez Adeline Simon Bérengère Dalmais Jean‐Marc Pradier Pascal Le Pêcheur Alex Mercier Anne‐Sophie Walker Carlos Garrido Isidro González Collado Muriel Viaud 《Environmental microbiology》2018,20(7):2469-2482
While abscisic acid (ABA) is known as a hormone produced by plants through the carotenoid pathway, a small number of phytopathogenic fungi are also able to produce this sesquiterpene but they use a distinct pathway that starts with the cyclization of farnesyl diphosphate (FPP) into 2Z,4E‐α‐ionylideneethane which is then subjected to several oxidation steps. To identify the sesquiterpene cyclase (STC) responsible for the biosynthesis of ABA in fungi, we conducted a genomic approach in Botrytis cinerea. The genome of the ABA‐overproducing strain ATCC58025 was fully sequenced and five STC‐coding genes were identified. Among them, Bcstc5 exhibits an expression profile concomitant with ABA production. Gene inactivation, complementation and chemical analysis demonstrated that BcStc5/BcAba5 is the key enzyme responsible for the key step of ABA biosynthesis in fungi. Unlike what is observed for most of the fungal secondary metabolism genes, the key enzyme‐coding gene Bcstc5/Bcaba5 is not clustered with the other biosynthetic genes, i.e., Bcaba1 to Bcaba4 that are responsible for the oxidative transformation of 2Z,4E‐α‐ionylideneethane. Finally, our study revealed that the presence of the Bcaba genes among Botrytis species is rare and that the majority of them do not possess the ability to produce ABA. 相似文献
973.
Bienvenu Thierry Hubert Dominique Fonknechten Nuria Dusser Daniel Kaplan Jean Claude Beldjord Cherif 《Human genetics》1994,94(1):65-68
Human Genetics - Cystic fibrosis is caused by mutations in the cystic fibrosis transmembrane conductance regulator gene (CFTR). Analysis of DNA from a pancreatic sufficient patient by means of... 相似文献
974.
Christin Munkebye Aarnes Inger Helene Madshus Jean Claude Guillemot Kirsten Sandvig Sjur Olsnes 《Experimental cell research》1987,170(2):483-490
Disulfide-linked conjugates of poliovirus with streptavidin or concanavalin A were formed and the binding of the conjugates to mouse L cells that lack natural poliovirus receptors was studied. The conjugate with streptavidin was specifically bound to biotinylated L cells, but not to unmodified L cells. The conjugate with conA was bound to L cells in the absence of, but not in the presence of alpha-methyl mannoside. Incubation of L cells with bound conjugates did not produce virus, although the conjugates were highly infectious in HeLa cells, containing natural poliovirus receptors. This suggests that the artificially bound virus was unable to penetrate the L cells and start replication. The possibility that binding of the virus to the natural receptor is required for efficient infection is discussed. 相似文献
975.
976.
Summary RP4-prime plasmids containing chromosomal fragments of either Escherichia coli or Rhizobium meliloti were constructed in vitro. When introduced into E. coli or R. meliloti respectively, they promoted a polarized transfer of the chromosome as demonstrated either by the gradient of transfer of various markers or by the study of the genetic constitution of recombinants. In E. coli, mobilization was shown to be dependent upon the presence of a functional rec A system. Inheritance of markers was due to their integration into the chromosome of the recipient as shown by the need for a functional rec A system in the recipient E. coli or by mobilization of recessive markers in R. meliloti. The system described could be applied to genetic mapping in any Gram negative bacteria. 相似文献
977.
Duarte Gouveia Lucia Grenga Jean‐Charles Gaillard Fabrice Gallais Laurent Bellanger Olivier Pible Jean Armengaud 《Proteomics》2020,20(14)
Detection of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) is a crucial tool for fighting the COVID‐19 pandemic. This dataset brief presents the exploration of a shotgun proteomics dataset acquired on SARS‐CoV‐2 infected Vero cells. Proteins from inactivated virus samples were extracted, digested with trypsin, and the resulting peptides were identified by data‐dependent acquisition tandem mass spectrometry. The 101 peptides reporting for six viral proteins were specifically analyzed in terms of their analytical characteristics, species specificity and conservation, and their proneness to structural modifications. Based on these results, a shortlist of 14 peptides from the N, S, and M main structural proteins that could be used for targeted mass‐spectrometry method development and diagnostic of the new SARS‐CoV‐2 is proposed and the best candidates are commented. 相似文献
978.
Pierre Soubeyran Carine Bellera Jean Goyard Damien Heitz Hervé Curé Hubert Rousselot Gilles Albrand Véronique Servent Olivier Saint Jean Isabelle van Praagh Jean-Emmanuel Kurtz Stéphane Périn Jean-Luc Verhaeghe Catherine Terret Christophe Desauw Véronique Girre Cécile Mertens Simone Mathoulin-Pélissier Muriel Rainfray 《PloS one》2014,9(12)
Background
Geriatric Assessment is an appropriate method for identifying older cancer patients at risk of life-threatening events during therapy. Yet, it is underused in practice, mainly because it is time- and resource-consuming. This study aims to identify the best screening tool to identify older cancer patients requiring geriatric assessment by comparing the performance of two short assessment tools the G8 and the Vulnerable Elders Survey (VES-13).Patients and Methods
The diagnostic accuracy of the G8 and the (VES-13) were evaluated in a prospective cohort study of 1674 cancer patients accrued before treatment in 23 health care facilities. 1435 were eligible and evaluable. Outcome measures were multidimensional geriatric assessment (MGA), sensitivity (primary), specificity, negative and positive predictive values and likelihood ratios of the G8 and VES-13, and predictive factors of 1-year survival rate.Results
Patient median age was 78.2 years (70-98) with a majority of females (69.8%), various types of cancer including 53.9% breast, and 75.8% Performance Status 0-1. Impaired MGA, G8, and VES-13 were 80.2%, 68.4%, and 60.2%, respectively. Mean time to complete G8 or VES-13 was about five minutes. Reproducibility of the two questionnaires was good. G8 appeared more sensitive (76.5% versus 68.7%, P = 0.0046) whereas VES-13 was more specific (74.3% versus 64.4%, P<0.0001). Abnormal G8 score (HR = 2.72), advanced stage (HR = 3.30), male sex (HR = 2.69) and poor Performance Status (HR = 3.28) were independent prognostic factors of 1-year survival.Conclusion
With good sensitivity and independent prognostic value on 1-year survival, the G8 questionnaire is currently one of the best screening tools available to identify older cancer patients requiring geriatric assessment, and we believe it should be implemented broadly in daily practice. Continuous research efforts should be pursued to refine the selection process of older cancer patients before potentially life-threatening therapy. 相似文献979.