全文获取类型
收费全文 | 1498篇 |
免费 | 97篇 |
学科分类
工业技术 | 1595篇 |
出版年
2024年 | 2篇 |
2023年 | 15篇 |
2022年 | 17篇 |
2021年 | 185篇 |
2020年 | 57篇 |
2019年 | 50篇 |
2018年 | 39篇 |
2017年 | 42篇 |
2016年 | 69篇 |
2015年 | 63篇 |
2014年 | 57篇 |
2013年 | 125篇 |
2012年 | 92篇 |
2011年 | 122篇 |
2010年 | 76篇 |
2009年 | 76篇 |
2008年 | 101篇 |
2007年 | 62篇 |
2006年 | 32篇 |
2005年 | 45篇 |
2004年 | 34篇 |
2003年 | 36篇 |
2002年 | 31篇 |
2001年 | 15篇 |
2000年 | 15篇 |
1999年 | 20篇 |
1998年 | 18篇 |
1997年 | 15篇 |
1996年 | 12篇 |
1995年 | 10篇 |
1994年 | 11篇 |
1993年 | 8篇 |
1992年 | 9篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有1595条查询结果,搜索用时 187 毫秒
981.
Investigating physicochemical,volatile and sensory parameters playing a positive or a negative role on tomato liking 总被引:1,自引:0,他引:1
982.
Moshe Tordjman Asaf Bolker Cecile Saguy Emanuel Baskin Paola Bruno Dieter M. Gruen Rafi Kalish 《Advanced functional materials》2012,22(9):1827-1834
Innovative memory switch devices require reliable bistable conductance properties. It would be desirable if such bistable characteristics were available in robust solid state materials, such as diamond, which benefit from outstanding physical properties. A bistable current with reversible switching effect from surface transfer doped ultrananocrystalline diamond thin films measured by electron field emission is reported. This switching is manifested by the appearance of huge jumps in the current emission, up to four orders of magnitude, that occur at specific extracting electric field values. Persistent hysteresis is exhibited whenever the field is ramped down. It is proposed that these phenomena are the result of resonant‐tunneling through a double barrier junction composed of tetrahedral amorphous carbon (ta‐C)/nanodiamond/adsorbent/vacuum. This finding may pave the way for the realization of novel types of memory switch devices with unprecedented performance. 相似文献
983.
Cremonesi P Vanoni L Morandi S Silvetti T Castiglioni B Brasca M 《International journal of food microbiology》2011,146(2):207-211
A pentaplex PCR assay for the rapid, selective and simultaneous detection of Lactobacillus helveticus, L. delbrueckii subsp. lactis, L. delbrueckii subsp. bulgaricus, Streptococcus thermophilus, and L. fermentum, was developed. The target sequences were a group of genes coding for beta-galactosidase production (S. thermophilus and L. delbrueckii subsp. bulgaricus), for cell-enveloped associated proteinase synthesis (L. helveticus), for dipeptide transport system production (L. delbrueckii subsp. lactis) and for arginine-ornithine antiporter protein production (L. fermentum). The analytical specificity of the assay was evaluated with 5 reference strains and 140 lactic acid bacterial strains derived from raw milk cheeses and belonging to the Lactobacillus, Streptococcus, Lactococcus and Enterococcus genera. The identification limit for each target strain was 103 CFU/ml. This new molecular assay was used to investigate the LAB population by direct extraction of DNA from the 12 whey cultures for Grana Padano. The pentaplex PCR assay revealed a good correspondence with microbiological analyses and allowed to identify even minor LAB community members which, can be out-competed in vitro by numerically more abundant microbial species. 相似文献
984.
Impact of fuel quality regulation and speed reductions on shipping emissions: implications for climate and air quality 总被引:1,自引:0,他引:1
Lack DA Cappa CD Langridge J Bahreini R Buffaloe G Brock C Cerully K Coffman D Hayden K Holloway J Lerner B Massoli P Li SM McLaren R Middlebrook AM Moore R Nenes A Nuaaman I Onasch TB Peischl J Perring A Quinn PK Ryerson T Schwartz JP Spackman R Wofsy SC Worsnop D Xiang B Williams E 《Environmental science & technology》2011,45(20):9052-9060
Atmospheric emissions of gas and particulate matter from a large ocean-going container vessel were sampled as it slowed and switched from high-sulfur to low-sulfur fuel as it transited into regulated coastal waters of California. Reduction in emission factors (EFs) of sulfur dioxide (SO?), particulate matter, particulate sulfate and cloud condensation nuclei were substantial (≥ 90%). EFs for particulate organic matter decreased by 70%. Black carbon (BC) EFs were reduced by 41%. When the measured emission reductions, brought about by compliance with the California fuel quality regulation and participation in the vessel speed reduction (VSR) program, are placed in a broader context, warming from reductions in the indirect effect of SO? would dominate any radiative changes due to the emissions changes. Within regulated waters absolute emission reductions exceed 88% for almost all measured gas and particle phase species. The analysis presented provides direct estimations of the emissions reductions that can be realized by California fuel quality regulation and VSR program, in addition to providing new information relevant to potential health and climate impact of reduced fuel sulfur content, fuel quality and vessel speed reductions. 相似文献
985.
Vanzani P Rossetto M De Marco V Sacchetti LE Paoletti MG Rigo A 《Journal of food science》2011,76(1):C46-C51
Some wild Mediterranean plants used as traditional food are an extraordinary source of antioxidants. We tested some properties of 10 of these herbaceous plants, used in Liguria (Northwest Italy) to prepare a traditional dish known as "prebuggiun." A total of 9 of them were found to have a polyphenol content and antioxidant properties similar or better than those of red chicory and blueberry, which are, in the case of vegetables and fruits, among the richest of antioxidants. Practical Application: In this article, we reported a study on wild plants growing in the Mediterranean area. These herbs have been neglected and this study aimed to revalue these plants because they are an extraordinary source of antioxidants. The increasing demand for natural antioxidants (additives in the food industry too) justifies the search for new sources of natural antioxidants. The revaluation of these plants will be interesting for: (1) consumer health, rediscovering a vegetable source of high antioxidant power; (2) possibility of producing new commercial products, such as food supplements of high quality and low cost; (3) pharmacological applications. 相似文献
986.
Fantuzzi A Mak LH Capria E Dodhia V Panicco P Collins S Gilardi G 《Analytical chemistry》2011,83(10):3831-3839
Over the past two decades, a wealth of information on the human cytochrome P450 enzymes and their role in drug metabolism both in vitro and in vivo has been gathered. Our understanding of this area has progressed greatly, but our confidence in the development of quantitative projections of drug interactions, made from in vitro data, is somehow still shaky. There are therefore no doubts in the necessity for reliable and fast methodologies for P450 drug metabolism analysis, capable of providing accurate and precise in vitro data. This paper reports on the first integration of a P450-electrode into a microtiter plate format for the rapid determination of the affinity parameters (K(M)) for a set of known drugs. The most relevant human drug metabolizing cytochromes P450, isoforms 3A4, 2D6, and 2C9, have been covalently bound to a gold electrode via a 10-carboxydecanethiol and 8-hydroxyoctanethiol (1:1) self-assembled monolayer at the bottom of an eight-well microtiter plate. The electrochemical response of the P450-electrode and the performance of the platform have been validated using a set of 30 known drugs with K(M) values spanning from less than 1 to more than 100 μM. The K(M) values obtained using this platform show an excellent error, and their ranking is within the range of those present in the literature determined from conventional incubation experiments with cytochrome P450s 3A4, 2D6, and 2C9. 相似文献
987.
Fractional power-law nonlinear drift arises in many applications of engineering interest, as in structures with nonlinear fluid viscous-elastic dampers. The probabilistic characterization of such structures under external Gaussian white noise excitation is still an open problem.This paper addresses the solution of such a nonlinear system providing the equation governing the evolution of the characteristic function, which involves the Riesz fractional operator. An efficient numerical procedure to handle the problem is also proposed. 相似文献
988.
Maria Giovanna Gandolfi Paola Taddei Anna Tinti Elettra De Stefano Dorigo Carlo Prati 《Materials science & engineering. C, Materials for biological applications》2011,31(7):1412-1422
The in vitro apatite-forming ability of experimental calcium-silicate hydraulic cements designed for dentistry was investigated.Two cements containing di- and tricalcium-silicate (wTC and wTC-TCP, i.e. wTC added with alpha-TCP) were soaked in different phosphate-containing solutions, namely Dulbecco's Phosphate Buffered Saline (DPBS) or Hank's Balanced Salt Solution (HBSS), at 37 °C and investigated over time (from 24 h to 6 months) by SEM/EDX, micro-Raman and ATR-FTIR.The early formation (24 h) of an aragonite/calcite layer onto both cements in both media was observed. Calcium phosphate deposits precipitated within 1–3 days in DPBS; spherical particles (spherulites) of apatite appeared after 3–7 days. wTC-TCP cement showed earlier, thicker and more homogeneous calcium phosphate deposits than wTC.In HBSS calcite deposits were mainly noticed, while phosphate bands appeared only after 7 days; the presence of globular deposits after 14–28 days was mostly detected on wTC-TCP.After 6 months, an approx. 900 micron carbonated apatite layer formed in DPBS whilst a 150–350 micron thick calcite/apatite layer generated in HBSS. Also in HBSS the carbonated apatite coating was earlier and thicker on wTC-TCP than wTC.Calcium-silicate cements showed the formation of a bone-like apatite layer, depending on the medium composition and ageing time. The addition of alpha-TCP increases the apatite-forming ability of calcium-silicate cements.Calcium-silicate hydraulic cements doped with alfa-TCP represent attractive materials to improve apical bone healing. 相似文献
989.
Monica Monici Francesca Cialdai Giovanni Romano Paola Antonia Corsetto Angela Maria Rizzo Anna Caselli Francesco Ranaldi 《Microgravity science and technology》2013,25(1):35-42
Microgravity-induced muscle atrophy is a problem of utmost importance for the impact it may have on the health and performance of astronauts. Therefore, appropriate countermeasures are needed to prevent disuse atrophy and favour muscle recovery. Muscle atrophy is characterized by loss of muscle mass and strength, and a shift in substrate utilization from fat to glucose, that leads to a reduced metabolic efficiency and enhanced fatigability. Laser therapy is already used in physical medicine and rehabilitation to accelerate muscle recovery and in sports medicine to prevent damages produced by metabolic disturbances and inflammatory reactions after heavy exercise. The aim of the research we present was to get insights on possible benefits deriving from the application of an advanced infrared laser system to counteract deficits of muscle energy metabolism and stimulate the recovery of the hypotrophic tissue. The source used was a Multiwave Locked System (MLS) laser, which combines continuous and pulsed emissions at 808 nm and 905 nm, respectively. We studied the effect of MLS treatment on morphology and energy metabolism of C2C12 cells, a widely accepted myoblast model, previously exposed to microgravity conditions modelled by a Random Positioning Machine. The MLS laser treatment was able to restore basal levels of serine/threonine protein phosphatase activity and to counteract cytoskeletal alterations and increase in glycolytic enzymes activity that occurred following the exposure to modelled microgravity. In conclusion, the results provide interesting insights for the application of infrared laser in the treatment of muscle atrophy. 相似文献
990.