全文获取类型
收费全文 | 1081篇 |
免费 | 94篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 6篇 |
综合类 | 3篇 |
化学工业 | 577篇 |
金属工艺 | 7篇 |
机械仪表 | 19篇 |
建筑科学 | 29篇 |
能源动力 | 27篇 |
轻工业 | 141篇 |
水利工程 | 4篇 |
石油天然气 | 1篇 |
无线电 | 79篇 |
一般工业技术 | 171篇 |
冶金工业 | 27篇 |
原子能技术 | 1篇 |
自动化技术 | 84篇 |
出版年
2024年 | 2篇 |
2023年 | 20篇 |
2022年 | 173篇 |
2021年 | 177篇 |
2020年 | 38篇 |
2019年 | 36篇 |
2018年 | 47篇 |
2017年 | 29篇 |
2016年 | 53篇 |
2015年 | 40篇 |
2014年 | 52篇 |
2013年 | 70篇 |
2012年 | 56篇 |
2011年 | 89篇 |
2010年 | 47篇 |
2009年 | 38篇 |
2008年 | 36篇 |
2007年 | 30篇 |
2006年 | 27篇 |
2005年 | 26篇 |
2004年 | 19篇 |
2003年 | 10篇 |
2002年 | 9篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 5篇 |
1998年 | 3篇 |
1997年 | 5篇 |
1996年 | 7篇 |
1995年 | 6篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有1176条查询结果,搜索用时 31 毫秒
91.
Giulietta Smulevich Enrica Droghetti Claudia Focardi Massimo Coletta Chiara Ciaccio Mila Nocentini 《Food chemistry》2007,101(3):1071-1077
Carbon monoxide (CO) can be used to treat fresh meat and fish in order to retain its ‘fresh’ red colour appearance for a longer period of time. In fact, upon aging, myoglobin is oxidized to met-myoglobin with the concomitant blue-shift and broadening of the Soret maximum, which brings about a change in the colour of the fish, revealing that it is no longer fresh. The use of carbon monoxide, which reacts with the oxy-myoglobin to form a fairly stable cherry red carboxy-myoglobin complex may mask spoilage, because the CO-complex can be stable beyond the microbiological shelf life of the meat. The presence of CO in tuna fish has been investigated by optical spectroscopy as the formation of the CO adduct can be easily detected by the combined analysis of electronic absorption spectra in their normal and second derivative modes, monitoring the intense Soret band at 420 nm. The presence of met- and oxy-myoglobin can obscure the presence of small amounts of the CO adduct; however, it can be revealed by chemically reducing the met- and oxy-forms to the deoxy-form in an anaerobic environment. This spectroscopic method provides a qualitatively rapid laboratory screening procedure for food control to unmask the presence of CO in frozen or fresh fish. 相似文献
92.
Crashworthiness of helicopter subfloor structures 总被引:7,自引:0,他引:7
To improve a helicopter design concept, which meets structural and crashworthiness requirements, a research program is undertaken to study the energy absorption capability of a subfloor structure. In particular, crash tests are performed on the subfloor structure and on the intersection elements, which are components of the structure and can create high deceleration peak loads at the cabin floor level causing dangerous inputs to the occupants. Then the structures are analysed by a commercial explicit finite element code, PAM-CRASH, using detailed geometrical models, suitable materials models and the appropriate definition of contact forces and rivets. The analysis shows that the load-shortening diagrams present a good correlation to the experimental data and that the structural collapse predictions correspond closely to the observed behaviour during the experimental tests. Consequently the finite element analysis can be used to aid the designers in evaluating the crashworthiness of different structural concepts and can therefore be an important mean of reducing development costs. 相似文献
93.
On the main flow features and instabilities in an unbaffled vessel agitated with an eccentrically located impeller 总被引:1,自引:0,他引:1
The hydrodynamics of an unbaffled vessel stirred by an eccentrically located Rushton turbine is investigated with both Laser Doppler Anemometry and flow visualisation techniques. The flow field is shown to be characterised by a strong circumferential motion which develops itself around two main vortices, one above and one below the impeller, both inclined with respect to the vertical plane. Such vortices are not steady but move periodically very slowly in comparison to the impeller rotational timescale. Accordingly, two low frequency components, whose values are linearly dependent on the impeller rotational speed, are identified across the vessel. The energetic contribution to the turbulent kinetic energy of such flow instabilities is significant so that they should be taken into account when evaluating micro-mixing information from turbulence quantities. Besides, an additional low frequency component is observed and related to vortex shedding phenomena from the flow-shaft interaction which occur in eccentric agitation operation. The flow discharged from the impeller is also measured and discussed. 相似文献
94.
95.
Sara Gnavi Benedetta Elena Fornasari Chiara Tonda-Turo Rossella Laurano Marco Zanetti Gianluca Ciardelli Stefano Geuna 《International journal of molecular sciences》2015,16(6):12925-12942
Electrospun fibrous substrates mimicking extracellular matrices can be prepared by electrospinning, yielding aligned fibrous matrices as internal fillers to manufacture artificial nerves. Gelatin aligned nano-fibers were prepared by electrospinning after tuning the collector rotation speed. The effect of alignment on cell adhesion and proliferation was tested in vitro using primary cultures, the Schwann cell line, RT4-D6P2T, and the sensory neuron-like cell line, 50B11. Cell adhesion and proliferation were assessed by quantifying at several time-points. Aligned nano-fibers reduced adhesion and proliferation rate compared with random fibers. Schwann cell morphology and organization were investigated by immunostaining of the cytoskeleton. Cells were elongated with their longitudinal body parallel to the aligned fibers. B5011 neuron-like cells were aligned and had parallel axon growth when cultured on the aligned gelatin fibers. The data show that the alignment of electrospun gelatin fibers can modulate Schwann cells and axon organization in vitro, suggesting that this substrate shows promise as an internal filler for the design of artificial nerves for peripheral nerve reconstruction. 相似文献
96.
Silvia Cammarano Valerio Roberto Maria Lo Verso Chiara Aghemo 《Building Research & Information》2015,43(2):222-237
Results are presented from a parametric study that assessed the amount of daylight in rooms with different architectural features: the orientation, window size and visible glazing transmittance, room depth, external obstruction angle and site. Annual lighting simulations were run in order to understand how the daylight availability within a space changes as a function of the architectural features. A sub-dataset of the full result database is examined in detail for north- and south-facing rooms in Turin, north-west Italy, with a visible glazing transmittance of 70%. Each feature is analysed for its influence on the daylighting conditions. A simple graphical tool is presented to promote an easier reading of the results. This was developed to provide a synthesis of information to the design team. It shows the influence of preliminary design solutions on the amount of indoor daylight. This allows a design team to assess indoor daylighting from the earliest design phases onwards and to determine which combinations of architectural features are able to provide high, acceptable or low daylight levels within a room. 相似文献
97.
Fernanda Andreola Luisa Barbieri Isabella Lancellotti Maria Chiara Bignozzi Franco Sandrolini 《International Journal of Applied Ceramic Technology》2010,7(4):546-555
Waste generated in ceramic tiles manufacturing is not usually recycled inside the productive plant, but rather disposed to landfill. This paper deals with ceramic residues from polishing and glazing processes, as constituents for innovative blended cements. New binders made up of 75% CEM I 52.5 R and 25% residues were chemically, physically, and mechanically characterized with reference to EN 197-1 requirements and the results compared with ordinary Portland cement. Mechanical strength development and microstructure of the relevant mortar have been investigated up to 90 days of curing, and the behavior of polishing and glazing residues as cement constituents is reported. 相似文献
98.
99.
Sousa F Mandal S Garrovo C Astolfo A Bonifacio A Latawiec D Menk RH Arfelli F Huewel S Legname G Galla HJ Krol S 《Nanoscale》2010,2(12):2826-2834
In the present study, the in vivo distribution of polyelectrolyte multilayer coated gold nanoparticles is shown, starting from the living animal down to cellular level. The coating was designed with functional moieties to serve as a potential nano drug for prion disease. With near infrared time-domain imaging we followed the biodistribution in mice up to 7 days after intravenous injection of the nanoparticles. The peak concentration in the head of mice was detected between 19 and 24 h. The precise particle distribution in the brain was studied ex vivo by X-ray microtomography, confocal laser and fluorescence microscopy. We found that the particles mainly accumulate in the hippocampus, thalamus, hypothalamus, and the cerebral cortex. 相似文献
100.
Chiara Falciani Dr. Jlenia Brunetti Dr. Chiara Pagliuca Dr. Stefano Menichetti Prof. Lucia Vitellozzi Barbara Lelli Dr. Alessandro Pini Dr. Luisa Bracci Prof. 《ChemMedChem》2010,5(4):567-574
The use of peptide receptors as targets for tumor‐selective therapies was envisaged years ago with the findings that receptors for different endogenous regulatory peptides are overexpressed in several primary and metastatic human tumors, and can be used as tumor antigens. Branched peptides can retain or even increase, through multivalent binding, the biological activity of a peptide and are very resistant to proteolysis, thus having a markedly higher in vivo activity compared with the corresponding monomeric peptides. Oligo‐branched peptides, containing the human regulatory peptide neurotensin (NT) sequence, have been used as tumor‐specific targeting agents. These peptides are able to selectively and specifically deliver effector units, for cell imaging or killing, to tumor cells that overexpress NT receptors. Results obtained with branched NT conjugated to different functional units for tumor imaging and therapy indicate that branched peptides are promising novel multifunctional targeting molecules. This study is focused on the role of the releasing pattern of drug‐conjugated branched NT peptides. We present results obtained with oligo‐branched neurotensin peptides conjugated to 6‐mercaptopurin (6‐MP), combretastain A‐4 (CA4) and monastrol (MON). Drugs were conjugated to oligo‐branched neurotensin through different linkers, and the mode‐of‐release, together with cytotoxicity, was studied in different human cancer cell lines. The results show that branched peptides are very promising pharmacodelivery options. Among our drug‐armed branched peptides, NT4–CA4 was identified as a candidate for further development and evaluation in preclinical pharmacokinetic and pharmacodynamic studies. This peptide–drug exhibits significant activity against pancreas and prostate human cancer cells. Consequently, this derivative is of considerable interest due to the high mortality rates of pancreas neuroendocrine tumors and the high incidence of prostate cancer. 相似文献