全文获取类型
收费全文 | 53048篇 |
免费 | 5344篇 |
国内免费 | 1791篇 |
出版年
2024年 | 133篇 |
2023年 | 1089篇 |
2022年 | 1356篇 |
2021年 | 2594篇 |
2020年 | 2757篇 |
2019年 | 3671篇 |
2018年 | 2731篇 |
2017年 | 1853篇 |
2016年 | 1762篇 |
2015年 | 2263篇 |
2014年 | 3643篇 |
2013年 | 4025篇 |
2012年 | 2105篇 |
2011年 | 2721篇 |
2010年 | 1813篇 |
2009年 | 2252篇 |
2008年 | 2329篇 |
2007年 | 2314篇 |
2006年 | 2213篇 |
2005年 | 1906篇 |
2004年 | 1597篇 |
2003年 | 1360篇 |
2002年 | 1165篇 |
2001年 | 828篇 |
2000年 | 743篇 |
1999年 | 577篇 |
1998年 | 638篇 |
1997年 | 592篇 |
1996年 | 624篇 |
1995年 | 593篇 |
1994年 | 557篇 |
1993年 | 497篇 |
1992年 | 529篇 |
1991年 | 446篇 |
1990年 | 408篇 |
1989年 | 356篇 |
1988年 | 316篇 |
1987年 | 313篇 |
1986年 | 247篇 |
1985年 | 305篇 |
1984年 | 294篇 |
1983年 | 153篇 |
1982年 | 255篇 |
1981年 | 207篇 |
1980年 | 185篇 |
1979年 | 183篇 |
1978年 | 119篇 |
1977年 | 116篇 |
1976年 | 110篇 |
1973年 | 80篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
《Cell reports》2020,30(3):630-641.e5
- Download : Download high-res image (118KB)
- Download : Download full-size image
52.
The production of d-aminoacylase by Alcaligenes denitrificans and Alcaligenes faecalis has been studied. The enzyme was inducibly produced and N-acetyl-d-leucine and N-acetyl-d-valine were the most effective inducers. d-methionine, d-valine, d-phenylalamine and d-leucine were produced by the enzymic hydrolysis of the appropriate N-acetyl-d-amino-acids with whole cell biomass. The hydrolysis of N-acetyl-d-methionine by A. denitrificans and N-acetyl-d-valine by A. faecalis was preferential. Maximum yields of d-methionine and d-valine were 94.3 and 84.7% at a specific product formation rate of 20.10 and 19.19 μmol min−1 mg−1 of wet cells at 20 mM substrate concentration and 5 mg ml−1 of cell density. 相似文献
53.
《基因组蛋白质组与生物信息学报(英文版)》2020,18(2):104-119
To address the increasing need for detecting and validating protein biomarkers in clinical specimens, mass spectrometry (MS)-based targeted proteomic techniques, including the selected reaction monitoring (SRM), parallel reaction monitoring (PRM), and massively parallel data-independent acquisition (DIA), have been developed. For optimal performance, they require the fragment ion spectra of targeted peptides as prior knowledge. In this report, we describe a MS pipeline and spectral resource to support targeted proteomics studies for human tissue samples. To build the spectral resource, we integrated common open-source MS computational tools to assemble a freely accessible computational workflow based on Docker. We then applied the workflow to generate DPHL, a comprehensive DIA pan-human library, from 1096 data-dependent acquisition (DDA) MS raw files for 16 types of cancer samples. This extensive spectral resource was then applied to a proteomic study of 17 prostate cancer (PCa) patients. Thereafter, PRM validation was applied to a larger study of 57 PCa patients and the differential expression of three proteins in prostate tumor was validated. As a second application, the DPHL spectral resource was applied to a study consisting of plasma samples from 19 diffuse large B cell lymphoma (DLBCL) patients and 18 healthy control subjects. Differentially expressed proteins between DLBCL patients and healthy control subjects were detected by DIA-MS and confirmed by PRM. These data demonstrate that the DPHL supports DIA and PRM MS pipelines for robust protein biomarker discovery. DPHL is freely accessible at https://www.iprox.org/page/project.html?id=IPX0001400000. 相似文献
54.
55.
《Cell reports》2020,30(2):421-431.e7
- Download : Download high-res image (176KB)
- Download : Download full-size image
56.
F F Smith J R Mertz I Krebs L L Tres C B Chae Z Zakeri J Engelhardt D Hoover M Tenniswood A L Kierszenbaum 《Molecular reproduction and development》1992,33(4):363-372
We have previously reported that a heterodimeric protein secreted by rat Sertoli cells is antigenically related to a protein associated with outer dense fibers of the sperm tail. Therefore, we have explored the possibility that Sertoli and spermatogenic cells express a similar gene encoding a homologous protein. A Sertoli cell heterodimeric protein cDNA probe recognizes specific mRNA in pachytene and round spermatids fractionated by centrifugal elutriation; however, this specific mRNA was less prominent than in cultured Sertoli cells. In agreement with these observations, in situ hybridization experiments show that Sertoli cells are predominantly engaged in active heterodimeric protein mRNA synthesis, while meiotic prophase spermatocytes and spermatids also show significant but less abundant specific mRNA. Immunoblotting experiments demonstrate that, while Sertoli cells synthesize a heterodimeric protein consisting of two disulfide-linked components with molecular masses of 45 and 35 kD, both primary spermatocytes and round spermatids synthesize single 30 kD monomers not associated by disulfide linkage but recognized by antisera to Sertoli cell heterodimeric protein. Immunoblotting and immunogold electron microscopic studies show that antisera to Sertoli cell heterodimeric protein recognize a protein associated with outer dense fibers. This immunoreactivity was abolished by a 5-min pronase treatment, without affecting the integrity of outer dense fibers. Results of this study and previous studies demonstrate that both Sertoli and spermatogenic cells express a similar gene and that an antigenically related product encoded by this gene becomes associated with outer dense fibers during their assembly at spermiogenesis. 相似文献
57.
58.
《Cell reports》2020,30(5):1530-1541.e4
- Download : Download high-res image (102KB)
- Download : Download full-size image
59.
G. Ricci L. Volpi L. Pasquali L. Petrozzi G. Siciliano 《Journal of biological physics》2009,35(4):317-336
Astrocytes have long been considered as just providing trophic support for neurons in the central nervous system, but recently
several studies have highlighted their importance in many functions such as neurotransmission, metabolite and electrolyte
homeostasis, cell signaling, inflammation, and synapse modulation. Astrocytes are, in fact, part of a bidirectional crosstalk
with neurons. Moreover, increasing evidence is stressing the emerging role of astrocyte dysfunction in the pathophysiology
of neurological disorders, including neurodegenerative disease, stroke, epilepsy, migraine, and neuroinflammatory diseases. 相似文献
60.