全文获取类型
收费全文 | 67757篇 |
免费 | 3860篇 |
国内免费 | 57篇 |
专业分类
电工技术 | 481篇 |
综合类 | 40篇 |
化学工业 | 12972篇 |
金属工艺 | 1268篇 |
机械仪表 | 1342篇 |
建筑科学 | 2021篇 |
矿业工程 | 133篇 |
能源动力 | 1395篇 |
轻工业 | 9641篇 |
水利工程 | 631篇 |
石油天然气 | 279篇 |
武器工业 | 5篇 |
无线电 | 3276篇 |
一般工业技术 | 11711篇 |
冶金工业 | 16987篇 |
原子能技术 | 315篇 |
自动化技术 | 9177篇 |
出版年
2023年 | 556篇 |
2022年 | 654篇 |
2021年 | 1500篇 |
2020年 | 1239篇 |
2019年 | 1298篇 |
2018年 | 2474篇 |
2017年 | 2436篇 |
2016年 | 2560篇 |
2015年 | 1878篇 |
2014年 | 2367篇 |
2013年 | 4791篇 |
2012年 | 3881篇 |
2011年 | 3648篇 |
2010年 | 2921篇 |
2009年 | 2659篇 |
2008年 | 2841篇 |
2007年 | 2542篇 |
2006年 | 1888篇 |
2005年 | 1585篇 |
2004年 | 1477篇 |
2003年 | 1312篇 |
2002年 | 1208篇 |
2001年 | 856篇 |
2000年 | 822篇 |
1999年 | 1021篇 |
1998年 | 5201篇 |
1997年 | 3333篇 |
1996年 | 2162篇 |
1995年 | 1296篇 |
1994年 | 1059篇 |
1993年 | 1105篇 |
1992年 | 390篇 |
1991年 | 403篇 |
1990年 | 360篇 |
1989年 | 352篇 |
1988年 | 337篇 |
1987年 | 287篇 |
1986年 | 292篇 |
1985年 | 335篇 |
1984年 | 293篇 |
1983年 | 214篇 |
1982年 | 284篇 |
1981年 | 306篇 |
1980年 | 294篇 |
1979年 | 197篇 |
1978年 | 194篇 |
1977年 | 458篇 |
1976年 | 983篇 |
1975年 | 139篇 |
1973年 | 141篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
The Journal of Supercomputing - Infrastructure-as-a-service container-based virtualization is gaining interest as a platform for running distributed applications. With increasing scale of cloud... 相似文献
32.
J. Cochard P. Léonide J. Borgomano Y. Guglielmi G. Massonnat J-P. Rolando L. Marié A. Pasquier 《Journal of Petroleum Geology》2020,43(1):75-94
Upper Barremian – Lower Aptian inner platform “Urgonian” limestones in the Mont de Vaucluse region, SE France, consist of alternating metre-scale microporous and tight intervals. This paper focuses on the influence of structural deformation on the reservoir properties of the Urgonian limestone succession in a study area near the town of Rustrel. Petrographic, petrophysical and structural data were recovered from five fully-cored boreholes, from the walls of a 100 m long underground tunnel, and from a 50 m long transect at a nearby outcrop. The data allowed reservoir property variations in the Urgonian limestones to be studied from core to reservoir scale. Eleven Reservoir Rock Types (RRTs) were identified based on petrographic features (texture, grain size), reservoir properties (porosity, permeability), and the frequency of structural discontinuities such as fractures, faults and stylolites. Tight and microporous reservoir rock types were distinguished. Tight reservoir rock types were characterised by early cementation of intergranular pore spaces and by the presence of frequent structural discontinuities. By contrast microporous reservoir rock types contained preserved intragranular microporosity and matrix permeability, but had very few structural discontinuities. Observed vertical alternations of microporous and tight rock types are interpreted to have been controlled by the early diagenesis of the Urgonian carbonates. Deformation associated with regional-scale tectonic phases, including Albian – Cenomanian “Durancian” uplift (∼105 to 96 Ma) and Pyrenean compression (∼55 to 25 Ma), resulted in the modification of the initial petrophysical properties of the Urgonian limestones. An early diagenetic imprint conditioned both the intensity of structural deformations and the associated circulations of diagenetic and meteoric fluids. Evolution of the Reservoir Rock Types is therefore linked both to the depositional conditions and to subsequent phases of structural deformation. 相似文献
33.
34.
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
35.
36.
Alexandra Kodadová Zuzana Vitková Petra Herdová Anton Ťažký Jarmila Oremusová Daniel Grančai 《Drug development and industrial pharmacy》2015,41(7):1080-1088
This study deals with the formulation of natural drugs into hydrogels. For the first time, compounds from the sage essential oil were formulated into chitosan hydrogels. A sample preparation procedure for hydrophobic volatile analytes present in a hydrophilic water matrix along with an analytical method based on the gas chromatography coupled with the mass spectrometry (GC-MS) was developed and applied for the evaluation of the identity and quantity of essential oil components in the hydrogels and saline samples. The experimental results revealed that the chitosan hydrogels are suitable for the formulation of sage essential oil. The monoterpene release can be effectively controlled by both chitosan and caffeine concentration in the hydrogels. Permeation experiment, based on a hydrogel with the optimized composition [3.5% (w/w) sage essential oil, 2.0% (w/w) caffeine, 2.5% (w/w) chitosan and 0.1% (w/w) Tween-80] in donor compartment, saline solution in acceptor compartment, and semi-permeable cellophane membrane, demonstrated the useful permeation selectivity. Here, (according to lipophilicity) an enhanced permeation of the bicyclic monoterpenes with antiflogistic and antiseptic properties (eucalyptol, camphor and borneol) and, at the same time, suppressed permeation of toxic thujone (not exceeding its permitted applicable concentration) was observed. These properties highlight the pharmaceutical importance of the developed chitosan hydrogel formulating sage essential oil in the dermal applications. 相似文献
37.
38.
39.
40.