全文获取类型
收费全文 | 34545篇 |
免费 | 2306篇 |
国内免费 | 30篇 |
专业分类
电工技术 | 256篇 |
综合类 | 17篇 |
化学工业 | 7011篇 |
金属工艺 | 674篇 |
机械仪表 | 739篇 |
建筑科学 | 976篇 |
矿业工程 | 85篇 |
能源动力 | 600篇 |
轻工业 | 5723篇 |
水利工程 | 323篇 |
石油天然气 | 123篇 |
武器工业 | 5篇 |
无线电 | 1346篇 |
一般工业技术 | 6057篇 |
冶金工业 | 7956篇 |
原子能技术 | 133篇 |
自动化技术 | 4857篇 |
出版年
2024年 | 83篇 |
2023年 | 318篇 |
2022年 | 319篇 |
2021年 | 828篇 |
2020年 | 732篇 |
2019年 | 812篇 |
2018年 | 1448篇 |
2017年 | 1432篇 |
2016年 | 1492篇 |
2015年 | 1129篇 |
2014年 | 1317篇 |
2013年 | 2815篇 |
2012年 | 2040篇 |
2011年 | 1853篇 |
2010年 | 1538篇 |
2009年 | 1361篇 |
2008年 | 1290篇 |
2007年 | 1196篇 |
2006年 | 795篇 |
2005年 | 678篇 |
2004年 | 647篇 |
2003年 | 581篇 |
2002年 | 569篇 |
2001年 | 424篇 |
2000年 | 399篇 |
1999年 | 445篇 |
1998年 | 2367篇 |
1997年 | 1622篇 |
1996年 | 1035篇 |
1995年 | 627篇 |
1994年 | 487篇 |
1993年 | 569篇 |
1992年 | 212篇 |
1991年 | 216篇 |
1990年 | 159篇 |
1989年 | 163篇 |
1988年 | 167篇 |
1987年 | 148篇 |
1986年 | 128篇 |
1985年 | 156篇 |
1984年 | 148篇 |
1983年 | 111篇 |
1982年 | 144篇 |
1981年 | 162篇 |
1980年 | 164篇 |
1979年 | 91篇 |
1978年 | 90篇 |
1977年 | 289篇 |
1976年 | 634篇 |
1973年 | 81篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
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
22.
23.
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
24.
25.
26.
The present study was conducted to develop subcritical water extraction (SWE) of Echinacea purpurea flowers. The influence of temperature and extraction time on quality of extracts considering total phenols content, total flavonoids content, antioxidant capacity and extraction yield, was determined. Optimized extraction parameters for maximised investigated responses were as follows: 147.56 °C and 8.43 min. The experimental values agreed with the values predicted, thus indicating the adequacy of central composite experimental design for modelling the SWE of bioactive compounds from E. purpurea. Results of the study also highlighted the potential application of E. purpurea subcritical water extracts as a source of valuable bioactive compounds. 相似文献
27.
28.
29.
ABSTRACTIn this paper, we review some algebraic control system. Precisely, linear and bilinear systems on Euclidean spaces and invariant and linear systems on Lie groups. The fourth classes of systems have a common issue: to any class, there exists an associated subgroup. From this object, we survey the controllability property. Especially, from those coming from our contribution to the theory. 相似文献
30.
This paper presents an analytical solution to the non-uniform pressure on thick-walled cylinder. The formulation is based on the linear elasticity theory (plain strain) and stress function method. As an example, the proposed solution is used to model the stress distribution due to non-uniform steel reinforcement corrosion in concrete. The model is formulated considering different scenarios of corrosion pressure distribution. It is validated against the finite element model for different cases of non-uniform pressure distributions. The results show that the corrosion-induced cracks are likely to start just beyond the anodic zone. This is confirmed by the experimental tests on concrete cylinder exposed to non-uniform accelerated corrosion of steel reinforcement. The model can be effectively used to calculate the distribution of corrosion-induced stresses in concrete. 相似文献