全文获取类型
收费全文 | 424704篇 |
免费 | 7279篇 |
国内免费 | 1406篇 |
专业分类
电工技术 | 7826篇 |
综合类 | 390篇 |
化学工业 | 64695篇 |
金属工艺 | 14538篇 |
机械仪表 | 12110篇 |
建筑科学 | 12245篇 |
矿业工程 | 910篇 |
能源动力 | 11554篇 |
轻工业 | 44831篇 |
水利工程 | 3418篇 |
石油天然气 | 1879篇 |
武器工业 | 13篇 |
无线电 | 56255篇 |
一般工业技术 | 78987篇 |
冶金工业 | 76654篇 |
原子能技术 | 5674篇 |
自动化技术 | 41410篇 |
出版年
2021年 | 3141篇 |
2020年 | 2112篇 |
2019年 | 2760篇 |
2018年 | 4255篇 |
2017年 | 4287篇 |
2016年 | 4597篇 |
2015年 | 3799篇 |
2014年 | 6195篇 |
2013年 | 20170篇 |
2012年 | 11005篇 |
2011年 | 15626篇 |
2010年 | 11960篇 |
2009年 | 13511篇 |
2008年 | 14573篇 |
2007年 | 14915篇 |
2006年 | 13259篇 |
2005年 | 12387篇 |
2004年 | 11882篇 |
2003年 | 11586篇 |
2002年 | 11180篇 |
2001年 | 11293篇 |
2000年 | 10427篇 |
1999年 | 10933篇 |
1998年 | 24168篇 |
1997年 | 17734篇 |
1996年 | 14044篇 |
1995年 | 11115篇 |
1994年 | 9890篇 |
1993年 | 9461篇 |
1992年 | 7217篇 |
1991年 | 6850篇 |
1990年 | 6491篇 |
1989年 | 6195篇 |
1988年 | 5922篇 |
1987年 | 4956篇 |
1986年 | 4911篇 |
1985年 | 6059篇 |
1984年 | 5674篇 |
1983年 | 4894篇 |
1982年 | 4569篇 |
1981年 | 4523篇 |
1980年 | 4263篇 |
1979年 | 4136篇 |
1978年 | 3822篇 |
1977年 | 4614篇 |
1976年 | 6145篇 |
1975年 | 3147篇 |
1974年 | 3047篇 |
1973年 | 2915篇 |
1972年 | 2345篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
52.
53.
Jakub Drzmisek Daniel Stipl Denisa Petrackova Branislav Vecerek Ana Dienstbier 《International journal of molecular sciences》2021,22(2)
Bacterial pathogens sense specific cues associated with different host niches and integrate these signals to appropriately adjust the global gene expression. Bordetella pertussis is a Gram-negative, strictly human pathogen of the respiratory tract and the etiological agent of whooping cough (pertussis). Though B. pertussis does not cause invasive infections, previous results indicated that this reemerging pathogen responds to blood exposure. Here, omics RNA-seq and LC–MS/MS techniques were applied to determine the blood-responsive regulon of B. pertussis. These analyses revealed that direct contact with blood rewired global gene expression profiles in B. pertussis as the expression of almost 20% of all genes was significantly modulated. However, upon loss of contact with blood, the majority of blood-specific effects vanished, with the exception of several genes encoding the T3SS-secreted substrates. For the first time, the T3SS regulator BtrA was identified in culture supernatants of B. pertussis. Furthermore, proteomic analysis identified BP2259 protein as a novel secreted T3SS substrate, which is required for T3SS functionality. Collectively, presented data indicate that contact with blood represents an important cue for B. pertussis cells. 相似文献
54.
Sarah Gilgunn Keefe Murphy Henning Stckmann Paul J. Conroy T. Brendan Murphy R. William Watson Richard J. OKennedy Pauline M. Rudd Radka Saldova 《International journal of molecular sciences》2020,21(23)
The diagnosis and treatment of prostate cancer (PCa) is a major health-care concern worldwide. This cancer can manifest itself in many distinct forms and the transition from clinically indolent PCa to the more invasive aggressive form remains poorly understood. It is now universally accepted that glycan expression patterns change with the cellular modifications that accompany the onset of tumorigenesis. The aim of this study was to investigate if differential glycosylation patterns could distinguish between indolent, significant, and aggressive PCa. Whole serum N-glycan profiling was carried out on 117 prostate cancer patients’ serum using our automated, high-throughput analysis platform for glycan-profiling which utilizes ultra-performance liquid chromatography (UPLC) to obtain high resolution separation of N-linked glycans released from the serum glycoproteins. We observed increases in hybrid, oligomannose, and biantennary digalactosylated monosialylated glycans (M5A1G1S1, M8, and A2G2S1), bisecting glycans (A2B, A2(6)BG1) and monoantennary glycans (A1), and decreases in triantennary trigalactosylated trisialylated glycans with and without core fucose (A3G3S3 and FA3G3S3) with PCa progression from indolent through significant and aggressive disease. These changes give us an insight into the disease pathogenesis and identify potential biomarkers for monitoring the PCa progression, however these need further confirmation studies. 相似文献
55.
56.
57.
58.
59.
Dr. Raysa Khan Tareque Dr. Storm Hassell-Hart Dr. Tobias Krojer Dr. Anthony Bradley Dr. Srikannathasan Velupillai Dr. Romain Talon Dr. Michael Fairhead Dr. Iain J. Day Kamlesh Bala Dr. Robert Felix Dr. Paul D. Kemmitt Prof. Paul Brennan Prof. Frank von Delft Dr. Laura Díaz Sáez Prof. Kilian Huber Prof. John Spencer 《ChemMedChem》2020,15(24):2513-2520
Combined photochemical arylation, “nuisance effect” (SNAr) reaction sequences have been employed in the design of small arrays for immediate deployment in medium-throughput X-ray protein–ligand structure determination. Reactions were deliberately allowed to run “out of control” in terms of selectivity; for example the ortho-arylation of 2-phenylpyridine gave five products resulting from mono- and bisarylations combined with SNAr processes. As a result, a number of crystallographic hits against NUDT7, a key peroxisomal CoA ester hydrolase, have been identified. 相似文献
60.
Lihua Lou Weijie Yu Ronald J. Kendall Ernest Smith Seshadri S. Ramkumar 《应用聚合物科学杂志》2020,137(30):49213
A tensile properties testing study was conducted to understand the influence of thickness, cross-head speed (speed of testing), gauge length (GL; specimen test length), and sample shape on important tensile properties of polyvinyl alcohol (PVA) nanofiber webs. The effects of each testing parameter on load at break, extension at break, Young's modulus, and tensile stress–strain curve of PVA nanofiber webs are analyzed. The Welch two sample t-tests show the significant difference among tested data. Using interaction plots, two-way analysis of variance, and margin mean plots, the interaction effects among testing parameters have been analyzed. Of all the factors, cross-head speed, the interaction among GL, and sample thickness (GL: Thickness) and the interaction among GL, testing speed and sample thickness (GL: Speed: Thickness) have significant influence on the tensile properties of PVA nanofiber webs. Moreover, the hypothesized model of mechanism of tensile strain–stress curve of PVA nanofiber webs has been proposed. Based on the model, the tensile strain–stress curve can be split into three stages: linear elastic, partial break up, and complete breakage. This study will provide a better understanding of tensile testing parameters' effects and their interaction effects on the tensile properties of nanowebs. 相似文献