全文获取类型
收费全文 | 944篇 |
免费 | 60篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 19篇 |
综合类 | 13篇 |
化学工业 | 251篇 |
金属工艺 | 22篇 |
机械仪表 | 26篇 |
建筑科学 | 56篇 |
矿业工程 | 4篇 |
能源动力 | 41篇 |
轻工业 | 62篇 |
水利工程 | 8篇 |
石油天然气 | 5篇 |
武器工业 | 8篇 |
无线电 | 80篇 |
一般工业技术 | 192篇 |
冶金工业 | 51篇 |
原子能技术 | 7篇 |
自动化技术 | 168篇 |
出版年
2023年 | 20篇 |
2022年 | 43篇 |
2021年 | 71篇 |
2020年 | 38篇 |
2019年 | 30篇 |
2018年 | 38篇 |
2017年 | 33篇 |
2016年 | 49篇 |
2015年 | 45篇 |
2014年 | 60篇 |
2013年 | 68篇 |
2012年 | 51篇 |
2011年 | 81篇 |
2010年 | 61篇 |
2009年 | 39篇 |
2008年 | 48篇 |
2007年 | 24篇 |
2006年 | 23篇 |
2005年 | 18篇 |
2004年 | 18篇 |
2003年 | 18篇 |
2002年 | 15篇 |
2001年 | 4篇 |
2000年 | 12篇 |
1999年 | 6篇 |
1998年 | 14篇 |
1997年 | 10篇 |
1996年 | 11篇 |
1995年 | 11篇 |
1994年 | 2篇 |
1993年 | 6篇 |
1992年 | 2篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1978年 | 3篇 |
1976年 | 3篇 |
1973年 | 7篇 |
1972年 | 2篇 |
1971年 | 3篇 |
1969年 | 8篇 |
1967年 | 1篇 |
1965年 | 2篇 |
1935年 | 2篇 |
排序方式: 共有1013条查询结果,搜索用时 11 毫秒
1.
With the emergence of distributed ledger technology (DLT), numerous practitioners and researchers have proclaimed its beneficial impact on supply chain transactions in the future. However, the vast majority of DLT initiatives are discontinued after a short period. With the full potential of DLT laying far down the road, especially managers in supply chain management (SCM) seek for short-term cost-saving effects of DLT in order to achieve long-term benefits of DLT in the future. However, the extant research has bypassed grounding long-term as well as short-term effects of DLT on supply chain transaction with empirical data. We address this shortcoming, following an abductive research approach and combining empirical data from a multiple case study design with the corresponding literature. Our study reveals that the effects of DLT on supply chain transactions are two-sided. We found six effects of DLT solutions that have a cost-reducing or cost avoidance impact on supply chain transactions. In addition, we found two effects that change the power distribution between buyers and suppliers in transactions and a single effect that reduces the dependency of supply chain transactions on third parties. While cost-reducing and avoidance as well as dependency-reducing effects are positive effects, the change in power distribution might come with disadvantages. With these findings, the paper provides the first empirical evidence of the impact of DLT on supply chain transactions, which will enable managers to improve their assessment of DLT usage in supply chains. 相似文献
2.
Ali Maghami Dominik Schillinger 《International journal for numerical methods in engineering》2020,121(5):967-989
We explore a truncation error criterion to steer adaptive step length refinement and coarsening in incremental-iterative path following procedures, applied to problems in large-deformation structural mechanics. Elaborating on ideas proposed by Bergan and collaborators in the 1970s, we first describe an easily computable scalar stiffness parameter whose sign and rate of change provide reliable information on the local behavior and complexity of the equilibrium path. We then derive a simple scaling law that adaptively adjusts the length of the next step based on the rate of change of the stiffness parameter at previous points on the path. We show that this scaling is equivalent to keeping a local truncation error constant in each step. We demonstrate with numerical examples that our adaptive method follows a path with a significantly reduced number of points compared to an analysis with uniform step length of the same fidelity level. A comparison with Abaqus illustrates that the truncation error criterion effectively concentrates points around the smallest-scale features of the path, which is generally not possible with automatic incrementation solely based on local convergence properties. 相似文献
3.
Jasmin Kuhn Philipp M. Klein Nader Al Danaf Joel Z. Nordin Sren Reinhard Dominik M. Loy Miriam Hhn Samir El Andaloussi Don C. Lamb Ernst Wagner Yoshitsugu Aoki Taavi Lehto Ulrich Lchelt 《Advanced functional materials》2019,29(48)
Phosphorodiamidate morpholino oligomers (PMOs) are oligonucleotide analogs that can be used for therapeutic modulation of pre‐mRNA splicing. Similar to other classes of nucleic acid‐based therapeutics, PMOs require delivery systems for efficient transport to the intracellular target sites. Here, artificial peptides based on the oligo(ethylenamino) acid succinyl‐tetraethylenpentamine (Stp), hydrophobic modifications, and an azide group are presented, which are used for strain‐promoted azide‐alkyne cycloaddition conjugation with splice‐switching PMOs. By systematically varying the lead structure and formulation, it is determined that the type of contained fatty acid and supramolecular assembly have a critical impact on the delivery efficacy. A compound containing linolenic acid with three cis double bonds exhibits the highest splice‐switching activity and significantly increases functional protein expression in pLuc/705 reporter cells in vitro and after local administration in vivo. Structural and mechanistic studies reveal that the lipopeptide PMO conjugates form nanoparticles, which accelerate cellular uptake and that the content of unsaturated fatty acids enhances endosomal escape. In an in vitro Duchenne muscular dystrophy exon skipping model using H2K‐mdx52 dystrophic skeletal myotubes, the highly potent PMO conjugates mediate significant splice‐switching at very low nanomolar concentrations. The presented aminoethylene‐lipopeptides are thus a promising platform for the generation of PMO‐therapeutics with a favorable activity/toxicity profile. 相似文献
4.
The cellulose solvent dimethyl sulfoxide (DMSO)/tetrabutylammonium fluoride trihydrate (TBAF) was
successfully applied as reaction medium for the synthesis of allyl cellulose by conversion of the polymer
with allyl chloride in the presence of solid NaOH. Samples with degree of substitution from 0.50 to 2.98
were accessible by varying the molar ratio anhydroglucose unit:allyl chloride:NaOH and reaction time. DMSO/TBAF
was found to be an efficient reaction medium for the preparation of highly functionalized samples from spruce
sulfite pulp with degree of polymerization of about 500 even in a scale of 50 g. The allyl cellulose samples
were characterized by means of FTIR- and NMR spectroscopy. Size exclusion chromatography revealed negligible
polymer degradation during synthesis and purification of the samples. 相似文献
5.
6.
J.L. Zeman 《International Journal of Pressure Vessels and Piping》1996,68(3):293-298
Progressive plastic deformation, or ratcheting, is a failure mechanism in ductile structures usually associated with non-proportional actions. In the case of cylindrical shell flat end connections, with or without opening, ratcheting may occur under the action of cyclically varying pressure from zero to a maximum value, i.e. for single action and, therefore, proportional loading. In this paper the ratcheting limits for this connection under this loading and for two different models are given, for an ideal-elastic ideal-plastic constitutive law, Mises' yield condition and associated flow law. The results are compared with each other and with the limits for global plastic deformation given in the literature. 相似文献
7.
Human can handle a deformable object and damp its vibration with recognized skill. However, for an industrial robot, handling a deformable object with acute vibration is often a difficult task. This paper addresses the problem of active damping skill for handling deformable linear objects (DLOs) by using a strategy inspired from human manipulation skills. The strategy is illustrated by several rules, which are explained by a fuzzy and a P controller. A proportional-integral-derivative (PID) controller is also employed to explain the rules as a comparison. The interpretations from controllers are translated into high level commands in a robotic language V+. A standard industrial robot with a force/torque sensor mounted on the wrist was employed to demonstrate the skill. Experimental results showed the fuzzy based damping skill is quite effective and stable even without any previous acknowledge of the deformable linear objects.Category (5) 相似文献
8.
Dominik Steup 《Journal of Infrared, Millimeter and Terahertz Waves》1993,14(12):2519-2532
Starting from a SMMW-multiplier design with quasioptical output two different multiplier compounds are presented. These new multipliers consist of a quasioptical antenna array in the output circuit which acts as a tunable power combiner. The multipliers work as quadruplers with an output frequency of 600 GHz. In all constructions the pump energy is fed into the diodes by a screened waveguide network. Optimum configurations for all arrays concerning quasioptical power combining are calculated and a theoretical comparison between the different multiplying conceptions is made. Finally some characteristic measurements of the quasioptical quadruplers are illustrated. 相似文献
9.
We present a filter-and-refine method to speed up nearest neighbor searches with the Kullback–Leibler divergence for multivariate
Gaussians. This combination of features and similarity estimation is of special interest in the field of automatic music recommendation
as it is widely used to compute music similarity. However, the non-vectorial features and a non-metric divergence make using
it with large corpora difficult, as standard indexing algorithms can not be used. This paper proposes a method for fast nearest
neighbor retrieval in large databases which relies on the above approach. In its core the method rescales the divergence and
uses a modified FastMap implementation to speed up nearest-neighbor queries. Overall the method accelerates the search for
similar music pieces by a factor of 10–30 and yields high recall values of 95–99% compared to a standard linear search. 相似文献
10.
Alexander Kutschera Ursula Schombel Dominik Schwudke Stefanie Ranf Nicolas Gisch 《International journal of molecular sciences》2021,22(6)
Lipopolysaccharide (LPS), the major component of the outer membrane of Gram-negative bacteria, is important for bacterial viability in general and host–pathogen interactions in particular. Negative charges at its core oligosaccharide (core-OS) contribute to membrane integrity through bridging interactions with divalent cations. The molecular structure and synthesis of the core-OS have been resolved in various bacteria including the mammalian pathogen Pseudomonas aeruginosa. A few core-OS structures of plant-associated Pseudomonas strains have been solved to date, but the genetic components of the underlying biosynthesis remained unclear. We conducted a comparative genome analysis of the core-OS gene cluster in Pseudomonas syringae pv. tomato (Pst) DC3000, a widely used model pathogen in plant–microbe interactions, within the P. syringae species complex and to other plant-associated Pseudomonas strains. Our results suggest a genetic and structural conservation of the inner core-OS but variation in outer core-OS composition within the P. syringae species complex. Structural analysis of the core-OS of Pst DC3000 shows an uncommonly high phosphorylation and presence of an O-acetylated sugar. Finally, we combined the results of our genomic survey with available structure information to estimate the core-OS composition of other Pseudomonas species. 相似文献