全文获取类型
收费全文 | 46623篇 |
免费 | 3688篇 |
国内免费 | 159篇 |
出版年
2018年 | 503篇 |
2017年 | 489篇 |
2016年 | 649篇 |
2015年 | 737篇 |
2014年 | 946篇 |
2013年 | 1118篇 |
2012年 | 1626篇 |
2011年 | 1755篇 |
2010年 | 947篇 |
2009年 | 931篇 |
2008年 | 1637篇 |
2007年 | 1647篇 |
2006年 | 1635篇 |
2005年 | 1411篇 |
2004年 | 1345篇 |
2003年 | 1279篇 |
2002年 | 1221篇 |
2001年 | 2991篇 |
2000年 | 2723篇 |
1999年 | 1932篇 |
1998年 | 618篇 |
1997年 | 518篇 |
1996年 | 462篇 |
1995年 | 409篇 |
1994年 | 394篇 |
1992年 | 1289篇 |
1991年 | 1166篇 |
1990年 | 1097篇 |
1989年 | 1047篇 |
1988年 | 932篇 |
1987年 | 927篇 |
1986年 | 802篇 |
1985年 | 796篇 |
1984年 | 567篇 |
1983年 | 519篇 |
1982年 | 371篇 |
1979年 | 632篇 |
1978年 | 455篇 |
1977年 | 415篇 |
1976年 | 374篇 |
1975年 | 495篇 |
1974年 | 578篇 |
1973年 | 557篇 |
1972年 | 573篇 |
1971年 | 558篇 |
1970年 | 529篇 |
1969年 | 528篇 |
1968年 | 435篇 |
1967年 | 372篇 |
1966年 | 410篇 |
排序方式: 共有10000条查询结果,搜索用时 16 毫秒
1.
Pedro Romón Z. Wilhelm De Beer Mercedes Fernández Julio Diez Brenda D. Wingfield Michael J. Wingfield 《Antonie van Leeuwenhoek》2014,106(6):1167-1184
Many bark beetles live in a symbiosis with ophiostomatoid fungi but very little is known regarding these fungi in Spain. In this study, we considered the fungi associated with nine bark beetle species and one weevil infesting two native tree species (Pinus sylvestris and Pinus nigra) and one non-native (Pinus radiata) in Cantabria (Northern Spain). This included examination of 239 bark beetles or their galleries. Isolations yielded a total of 110 cultures that included 11 fungal species (five species of Leptographium sensu lato including Leptographium absconditum sp. nov., five species of Ophiostoma sensu lato including Ophiostoma cantabriense sp. nov, and one species of Graphilbum). The most commonly encountered fungal associates of the bark beetles were Grosmannia olivacea, Leptographium procerum, and Ophiostoma canum. The aggressiveness of the collected fungal species was evaluated using inoculations on two-year-old P. radiata seedlings. Leptographium wingfieldii, Leptographium guttulatum, and Ophiostoma ips were the only species capable of causing significant lesions. 相似文献
2.
Quirijn R. J. G. Tummers Charlotte E. S. Hoogstins Alexander A. W. Peters Cor D. de Kroon J. Baptist M. Z. Trimbos Cornelis J. H. van de Velde John V. Frangioni Alexander L. Vahrmeijer Katja N. Gaarenstroom 《PloS one》2015,10(6)
Objective
In ovarian cancer, two of the most important prognostic factors for survival are completeness of staging and completeness of cytoreductive surgery. Therefore, intra-operative visualization of tumor lesions is of great importance. Preclinical data already demonstrated tumor visualization in a mouse-model using near-infrared (NIR) fluorescence imaging and indocyanine green (ICG) as a result of enhanced permeability and retention (EPR). The aim of this study was to determine feasibility of intraoperative ovarian cancer metastases imaging using NIR fluorescence imaging and ICG in a clinical setting.Methods
Ten patients suspected of ovarian cancer scheduled for staging or cytoreductive surgery were included. Patients received 20 mg ICG intravenously after opening the abdominal cavity. The mini-FLARE NIR fluorescence imaging system was used to detect NIR fluorescent lesions.Results
6 out of 10 patients had malignant disease of the ovary or fallopian tube, of which 2 had metastatic disease outside the pelvis. Eight metastatic lesions were detected in these 2 patients, which were all NIR fluorescent. However, 13 non-malignant lesions were also NIR fluorescent, resulting in a false-positive rate of 62%. There was no significant difference in tumor-to-background ratio between malignant and benign lesions (2.0 vs 2.0; P=0.99).Conclusions
This is the first clinical trial demonstrating intraoperative detection of ovarian cancer metastases using NIR fluorescence imaging and ICG. Despite detection of all malignant lesions, a high false-positive rate was observed. Therefore, NIR fluorescence imaging using ICG based on the EPR effect is not satisfactory for the detection of ovarian cancer metastases. The need for tumor-specific intraoperative agents remains.Trial Registration
ISRCTN Registry ISRCTN16945066 相似文献3.
Alexandro J. Martagón Jean Z. Lin Stephanie L. Cimini Paul Webb Kevin J. Phillips 《PloS one》2015,10(4)
Thyroid hormone receptor (TR) agonists have been proposed as therapeutic agents to treat non-alcoholic fatty liver disease (NAFLD) and insulin resistance. We investigated the ability of the TR agonists GC-1 and KB2115 to reduce hepatic steatosis in ob/ob mice. Both compounds markedly reduced hepatic triglyceride levels and ameliorated hepatic steatosis. However, the amelioration of fatty liver was not sufficient to improve insulin sensitivity in these mice and reductions in hepatic triglycerides did not correlate with improvements in insulin sensitivity or glycemic control. Instead, the effects of TR activation on glycemia varied widely and were found to depend upon the time of treatment as well as the compound and dosage used. Lower doses of GC-1 were found to further impair glycemic control, while a higher dose of the same compound resulted in substantially improved glucose tolerance and insulin sensitivity, despite all doses being equally effective at reducing hepatic triglyceride levels. Improvements in glycemic control and insulin sensitivity were observed only in treatments that also increased body temperature, suggesting that the induction of thermogenesis may play a role in mediating these beneficial effects. These data illustrate that the relationship between TR activation and insulin sensitivity is complex and suggests that although TR agonists may have value in treating NAFLD, their effect on insulin sensitivity must also be considered. 相似文献
4.
Vadim I. Nazarov Mikhail V. Pogorelyy Ekaterina A. Komech Ivan V. Zvyagin Dmitry A. Bolotin Mikhail Shugay Dmitry M. Chudakov Yury B. Lebedev Ilgar Z. Mamedov 《BMC bioinformatics》2015,16(1)
Background
The Immunoglobulins (IG) and the T cell receptors (TR) play the key role in antigen recognition during the adaptive immune response. Recent progress in next-generation sequencing technologies has provided an opportunity for the deep T cell receptor repertoire profiling. However, a specialised software is required for the rational analysis of massive data generated by next-generation sequencing.Results
Here we introduce tcR, a new R package, representing a platform for the advanced analysis of T cell receptor repertoires, which includes diversity measures, shared T cell receptor sequences identification, gene usage statistics computation and other widely used methods. The tool has proven its utility in recent research studies.Conclusions
tcR is an R package for the advanced analysis of T cell receptor repertoires after primary TR sequences extraction from raw sequencing reads. The stable version can be directly installed from The Comprehensive R Archive Network (http://cran.r-project.org/mirrors.html). The source code and development version are available at tcR GitHub (http://imminfo.github.io/tcr/) along with the full documentation and typical usage examples. 相似文献5.
6.
Identification of Campylobacter jejuni and determination of point mutations associated with macrolide resistance using a multiplex TaqMan MGB real‐time PCR 下载免费PDF全文
7.
Test methods and response surface models for hot,humid air decontamination of materials contaminated with dirty spores of Bacillus anthracis ∆Sterne and Bacillus thuringiensis Al Hakam 下载免费PDF全文
8.
9.
Jeella Z. Acedo Marco J. van Belkum Christopher T. Lohans Ryan T. McKay Mark Miskolzie John C. Vederas 《Applied and environmental microbiology》2015,81(8):2910-2918
Acidocin B, a bacteriocin produced by Lactobacillus acidophilus M46, was originally reported to be a linear peptide composed of 59 amino acid residues. However, its high sequence similarity to gassericin A, a circular bacteriocin from Lactobacillus gasseri LA39, suggested that acidocin B might be circular as well. Acidocin B was purified from culture supernatant by a series of hydrophobic interaction chromatographic steps. Its circular nature was ascertained by matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) mass spectrometry and tandem mass spectrometry (MS/MS) sequencing. The peptide sequence was found to consist of 58 amino acids with a molecular mass of 5,621.5 Da. The sequence of the acidocin B biosynthetic gene cluster was also determined and showed high nucleotide sequence similarity to that of gassericin A. The nuclear magnetic resonance (NMR) solution structure of acidocin B in sodium dodecyl sulfate micelles was elucidated, revealing that it is composed of four α-helices of similar length that are folded to form a compact, globular bundle with a central pore. This is a three-dimensional structure for a member of subgroup II circular bacteriocins, which are classified based on their isoelectric points of ∼7 or lower. Comparison of acidocin B with carnocyclin A, a subgroup I circular bacteriocin with four α-helices and a pI of 10, revealed differences in the overall folding. The observed variations could be attributed to inherent diversity in their physical properties, which also required the use of different solvent systems for three-dimensional structural elucidation. 相似文献
10.