全文获取类型
收费全文 | 811篇 |
免费 | 72篇 |
专业分类
883篇 |
出版年
2021年 | 14篇 |
2018年 | 12篇 |
2016年 | 8篇 |
2015年 | 16篇 |
2014年 | 21篇 |
2013年 | 24篇 |
2012年 | 23篇 |
2011年 | 24篇 |
2010年 | 23篇 |
2009年 | 21篇 |
2008年 | 30篇 |
2007年 | 29篇 |
2006年 | 22篇 |
2005年 | 35篇 |
2004年 | 29篇 |
2003年 | 26篇 |
2002年 | 23篇 |
2001年 | 22篇 |
2000年 | 22篇 |
1999年 | 25篇 |
1998年 | 18篇 |
1997年 | 11篇 |
1993年 | 9篇 |
1992年 | 20篇 |
1991年 | 17篇 |
1990年 | 28篇 |
1989年 | 13篇 |
1988年 | 20篇 |
1987年 | 12篇 |
1986年 | 17篇 |
1985年 | 18篇 |
1984年 | 19篇 |
1983年 | 10篇 |
1982年 | 7篇 |
1981年 | 13篇 |
1980年 | 9篇 |
1979年 | 14篇 |
1978年 | 14篇 |
1977年 | 8篇 |
1976年 | 11篇 |
1975年 | 10篇 |
1974年 | 7篇 |
1973年 | 14篇 |
1972年 | 9篇 |
1971年 | 8篇 |
1970年 | 9篇 |
1969年 | 10篇 |
1968年 | 7篇 |
1966年 | 6篇 |
1958年 | 6篇 |
排序方式: 共有883条查询结果,搜索用时 8 毫秒
51.
Metabarcoding of microbial eukaryotes (collectively known as protists) has developed tremendously in the last decade, almost solely relying on the 18S rRNA gene. As microbial eukaryotes are extremely diverse, many primers and primer pairs have been developed. To cover a relevant and representative fraction of the protist community in a given study system, an informed primer choice is necessary, as no primer pair can target all protists equally well. As such, a smart primer choice is very difficult even for experts and there are very few online resources available to list existing primers. We built a database listing 285 primers and 83 unique primer pairs that have been used for eukaryotic 18S rRNA gene metabarcoding. In silico performance of primer pairs was tested against two sequence databases: PR2 version 4.12.0 for eukaryotes and a subset of silva version 132 for bacteria and archaea. We developed an R -based web application enabling browsing of the database, visualization of the taxonomic distribution of the amplified sequences with the number of mismatches, and testing any user-defined primer or primer set ( https://app.pr2-primers.org ). Taxonomic specificity of primer pairs, amplicon size and location of mismatches can also be determined. We identified universal primer sets that matched the largest number of sequences and analysed the specificity of some primer sets designed to target certain groups. This tool enables guided primer choices that will help a wide range of researchers to include protists as part of their investigations. 相似文献
52.
Samuel J Atkinson Aleksander M Gontarczyk Abdullah AA Alghamdi Tim S Ellison Robert T Johnson Wesley J Fowler Benjamin M Kirkup Bernardo C Silva Bronwen E Harry Jochen G Schneider Katherine N Weilbaecher Mette M Mogensen Mark D Bass Maddy Parsons Dylan R Edwards Stephen D Robinson 《EMBO reports》2018,19(7)
Integrin β3 is seen as a key anti‐angiogenic target for cancer treatment due to its expression on neovasculature, but the role it plays in the process is complex; whether it is pro‐ or anti‐angiogenic depends on the context in which it is expressed. To understand precisely β3's role in regulating integrin adhesion complexes in endothelial cells, we characterised, by mass spectrometry, the β3‐dependent adhesome. We show that depletion of β3‐integrin in this cell type leads to changes in microtubule behaviour that control cell migration. β3‐integrin regulates microtubule stability in endothelial cells through Rcc2/Anxa2‐driven control of active Rac1 localisation. Our findings reveal that angiogenic processes, both in vitro and in vivo, are more sensitive to microtubule targeting agents when β3‐integrin levels are reduced. 相似文献
53.
Mediation of pinocytosis in cultured arterial smooth muscle and endothelial cells by platelet-derived growth factor 总被引:13,自引:10,他引:13 下载免费PDF全文
Pinocytosis was measured in monkey aortic smooth muscle cells (SMC), bovine aortic endothelial cells, and Swiss 3T3 cells in culture as cellular uptake of [U-(14)C]sucrose and horseradish peroxidase (HRP) from the tissue culture medium. Monkey arterial SMC and Swiss 3T3 cells were maintained in a quiescent state of growth at low cells density in medium containing 5 percent monkey plasma-derived serum (PDS). Replacement of PDS with 5 percent monkey whole blood serum (WBS) from the same donor, or addition to PDS of partially purified platelet-derived growth factor(s) (PF), resulted in a marked stimulation of pinocytosis as well as of cellular proliferation. In SMC, enhancement of the rate of pinocytosis occurred 4-6 h after exposure to WBS or PF, and the rate was up to twofold higher than the rate in medium containing PDS. In contrast, [(3)H]thymidine uptake by SMC did not increase until 12-16 h after exposure to PF. In endothelial cells the presence of PF or WBS did not enhance either the rate of pinocytosis or the rate of proliferation over that in PDS. Thus, endothelial cells did not become quiescent at subconfluent densities in PDS but maintained rates of proliferation and pinocytosis that were equivalent to those in WBS. By autoradiography, the fraction of labeled nuclei in SMC cultures 24 h after change of medium increased from 0.061 +/- 0.004 in quiescent cultures to 0.313 +/- 0.028 after exposure to WBS or PF. In contrast, labeling indices of endothelial cells were similar for cultures grown in PDS, WBS, or PF at any single time point after change of medium. These findings suggest that the rate of pinocytosis maybe be coupled in some fashion to growth regulation, which may be mediated in part by specific growth factors, such as that derived from the thrombocyte. 相似文献
54.
55.
Yongqi Deng Zhiwei Yang Gerald W. Shipps Sie-Mun Lo Robert West Joyce Hwa Shuqin Zheng Constance Farley Jean Lachowicz Margaret van Heek Alan S. Bass Dinesh P. Sinha Craig R. Mahon Mark E. Cartwright 《Bioorganic & medicinal chemistry letters》2013,23(3):791-796
Inhibitors based on a benzo-fused spirocyclic oxazepine scaffold were discovered for stearoyl-coenzyme A (CoA) desaturase 1 (SCD1) and subsequently optimized to potent compounds with favorable pharmacokinetic profiles and in vivo efficacy in reducing the desaturation index in a mouse model. Initial optimization revealed potency preferences for the oxazepine core and benzylic positions, while substituents on the piperidine portions were more tolerant and allowed for tuning of potency and PK properties. After preparation and testing of a range of functional groups on the piperidine nitrogen, three classes of analogs were identified with single digit nanomolar potency: glycine amides, heterocycle-linked amides, and thiazoles. Responding to concerns about target localization and potential mechanism-based side effects, an initial effort was also made to improve liver concentration in an available rat PK model. An advanced compound 17m with a 5-carboxy-2-thiazole substructure appended to the spirocyclic piperidine scaffold was developed which satisfied the in vitro and in vivo requirements for more detailed studies. 相似文献
56.
J. Stewart Welton Michael Ladle Jon A. B. Bass Kevin Chapman 《International Review of Hydrobiology》1981,66(3):407-414
In order to determine the efficacy of sampling benthic invertebrates to a depth of 100 mm as compared with 200 mm, the gravel substratum of an experimental recirculating stream was sampled to both depths. Except for 6 taxa which were significantly more numerous in the shallower samplers, there was no significant difference between the densities determined from the two depths. 相似文献
57.
58.
59.
60.
Chaitanya Pant Abhishek Deshpande Mojtaba Olyaee Michael P. Anderson Anas Bitar Marilyn I. Steele Pat F. Bass III Thomas J. Sferra 《PloS one》2014,9(5)