全文获取类型
收费全文 | 616191篇 |
免费 | 17565篇 |
国内免费 | 6911篇 |
专业分类
电工技术 | 15649篇 |
技术理论 | 7篇 |
综合类 | 9990篇 |
化学工业 | 93052篇 |
金属工艺 | 25949篇 |
机械仪表 | 22520篇 |
建筑科学 | 23385篇 |
矿业工程 | 4805篇 |
能源动力 | 16052篇 |
轻工业 | 55161篇 |
水利工程 | 6634篇 |
石油天然气 | 9463篇 |
武器工业 | 893篇 |
无线电 | 78338篇 |
一般工业技术 | 108295篇 |
冶金工业 | 84972篇 |
原子能技术 | 7231篇 |
自动化技术 | 78271篇 |
出版年
2022年 | 4478篇 |
2021年 | 7446篇 |
2020年 | 5448篇 |
2019年 | 5566篇 |
2018年 | 20629篇 |
2017年 | 20281篇 |
2016年 | 16792篇 |
2015年 | 8742篇 |
2014年 | 11821篇 |
2013年 | 26910篇 |
2012年 | 20820篇 |
2011年 | 31847篇 |
2010年 | 26299篇 |
2009年 | 25078篇 |
2008年 | 27013篇 |
2007年 | 28032篇 |
2006年 | 19750篇 |
2005年 | 19027篇 |
2004年 | 16679篇 |
2003年 | 15978篇 |
2002年 | 14844篇 |
2001年 | 14409篇 |
2000年 | 13711篇 |
1999年 | 14311篇 |
1998年 | 27561篇 |
1997年 | 20507篇 |
1996年 | 16546篇 |
1995年 | 13112篇 |
1994年 | 11503篇 |
1993年 | 10624篇 |
1992年 | 8110篇 |
1991年 | 7616篇 |
1990年 | 6975篇 |
1989年 | 6641篇 |
1988年 | 6294篇 |
1987年 | 5170篇 |
1986年 | 5024篇 |
1985年 | 6100篇 |
1984年 | 5681篇 |
1983年 | 4887篇 |
1982年 | 4570篇 |
1981年 | 4509篇 |
1980年 | 4249篇 |
1979年 | 4095篇 |
1978年 | 3780篇 |
1977年 | 4555篇 |
1976年 | 6114篇 |
1975年 | 3125篇 |
1974年 | 3016篇 |
1973年 | 2897篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Lü Qing Xu Bin Yu Yang Zhan Wei Zhao Yu Zheng Jun Ji Jian 《Bulletin of Engineering Geology and the Environment》2021,80(8):6513-6525
Bulletin of Engineering Geology and the Environment - Many uncertainties exist in pile-stabilized slopes which make their design substantially complicated. In this paper, a first-order reliability... 相似文献
92.
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
93.
王虔虔在上任中建材(合肥)粉体科技装备有限公司(简称粉体公司)总经理之前,和分管部门的所有同事坐在同一间大办公室内。之所以和大家在同一个空间内工作,王虔虔是想更进一步拉近彼此之间的距离,以身作则潜移默化,传承公司文化,建立相互信任的团队。2012年,粉体公司决定向"提供系统解决方案的综合服务商"转变。 相似文献
94.
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
95.
Lu Xu Baijun Liu Mingyao Zhang Yang Bai Jinming Zhang Jiayin Song 《Polymer Engineering and Science》2020,60(6):1194-1201
A series of methacrylate-acrylonitrile-butadiene-styrene (MABS) resins was prepared using bulk polymerization. The polarity of the continuous phase and the compatibility of two phases were changed by adjusting the methyl methacrylate (MMA) content, choosing values that were close to styrene-butadiene rubber solubility value. The possibility of controlling the microstructure of the MABS resin by changing the polarity of the components and the compatibility of two phases was assessed. The dynamic mechanical analysis shows that the compatibility of two phases varies with the MMA content. The morphological analysis shows that increasing MMA contents results in a gradual decrease in the sub-inclusion structure with a network skeleton of rubber particles, and that all the particles become solid rubber when the MMA content reaches 75%. The sub-inclusion structure reappears but does not have a network skeleton when the MMA content is 90%. The impact strength and morphological analysis indicate that the solid rubber particles and the sub-inclusion structure with a network skeleton provide excellent toughness, while the sub-inclusion structure without a network skeleton does not. In contrast, the transmittance of the ABS resin first increased and then decreased with increasing MMA content. 相似文献
96.
97.
98.
99.
Nicholas Caffes David B. Kurland Volodymyr Gerzanich J. Marc Simard 《International journal of molecular sciences》2015,16(3):4973-4984
Ischemic and hemorrhagic strokes are associated with severe functional disability and high mortality. Except for recombinant tissue plasminogen activator, therapies targeting the underlying pathophysiology of central nervous system (CNS) ischemia and hemorrhage are strikingly lacking. Sur1-regulated channels play essential roles in necrotic cell death and cerebral edema following ischemic insults, and in neuroinflammation after hemorrhagic injuries. Inhibiting endothelial, neuronal, astrocytic and oligodendroglial sulfonylurea receptor 1–transient receptor potential melastatin 4 (Sur1–Trpm4) channels and, in some cases, microglial KATP (Sur1–Kir6.2) channels, with glibenclamide is protective in a variety of contexts. Robust preclinical studies have shown that glibenclamide and other sulfonylurea agents reduce infarct volumes, edema and hemorrhagic conversion, and improve outcomes in rodent models of ischemic stroke. Retrospective studies suggest that diabetic patients on sulfonylurea drugs at stroke presentation fare better if they continue on drug. Additional laboratory investigations have implicated Sur1 in the pathophysiology of hemorrhagic CNS insults. In clinically relevant models of subarachnoid hemorrhage, glibenclamide reduces adverse neuroinflammatory and behavioral outcomes. Here, we provide an overview of the preclinical studies of glibenclamide therapy for CNS ischemia and hemorrhage, discuss the available data from clinical investigations, and conclude with promising preclinical results that suggest glibenclamide may be an effective therapeutic option for ischemic and hemorrhagic stroke. 相似文献
100.
ABSTRACT This study investigates the effects of strain, strain rates, and forming directions (RD-rolling direction, TD-transverse direction, and ND-normal direction) on adiabatic shear, via dynamic impact compression tests using the Split Hopkinson Pressure Bar (SHPB) apparatus. A modified Johnson-Cook (J-C) constitutive model is proposed, which used to analyse the influence of the constitutive parameters on the sensitivity of adiabatic shear, employing a finite element software. The different sensitivities of adiabatic shear under different directions are explained by combining microscopic analysis and results from mechanical responses. The results show that the sensitivity of adiabatic shear can be related to the time of stress collapse in the following trend: ND?>?TD?>?RD; the sensitivities of these constitutive parameters on adiabatic shear are calculated and compared. 相似文献