全文获取类型
收费全文 | 5858篇 |
免费 | 152篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 60篇 |
综合类 | 12篇 |
化学工业 | 940篇 |
金属工艺 | 132篇 |
机械仪表 | 119篇 |
建筑科学 | 216篇 |
矿业工程 | 38篇 |
能源动力 | 136篇 |
轻工业 | 580篇 |
水利工程 | 50篇 |
石油天然气 | 10篇 |
无线电 | 547篇 |
一般工业技术 | 723篇 |
冶金工业 | 1629篇 |
原子能技术 | 23篇 |
自动化技术 | 802篇 |
出版年
2022年 | 37篇 |
2021年 | 69篇 |
2020年 | 67篇 |
2019年 | 59篇 |
2018年 | 96篇 |
2017年 | 108篇 |
2016年 | 110篇 |
2015年 | 88篇 |
2014年 | 114篇 |
2013年 | 300篇 |
2012年 | 174篇 |
2011年 | 230篇 |
2010年 | 221篇 |
2009年 | 225篇 |
2008年 | 243篇 |
2007年 | 248篇 |
2006年 | 215篇 |
2005年 | 175篇 |
2004年 | 158篇 |
2003年 | 167篇 |
2002年 | 143篇 |
2001年 | 102篇 |
2000年 | 112篇 |
1999年 | 128篇 |
1998年 | 434篇 |
1997年 | 260篇 |
1996年 | 184篇 |
1995年 | 131篇 |
1994年 | 124篇 |
1993年 | 113篇 |
1992年 | 69篇 |
1991年 | 51篇 |
1990年 | 79篇 |
1989年 | 82篇 |
1988年 | 68篇 |
1987年 | 63篇 |
1986年 | 57篇 |
1985年 | 58篇 |
1984年 | 56篇 |
1983年 | 47篇 |
1982年 | 43篇 |
1981年 | 47篇 |
1980年 | 35篇 |
1979年 | 31篇 |
1978年 | 26篇 |
1977年 | 48篇 |
1976年 | 79篇 |
1974年 | 25篇 |
1973年 | 25篇 |
1971年 | 26篇 |
排序方式: 共有6017条查询结果,搜索用时 13 毫秒
121.
Beatriz Herranz Wenceslao Canet María José Jiménez Raúl Fuentes María Dolores Alvarez 《International Journal of Food Science & Technology》2016,51(5):1087-1098
Chickpea flour (CF)‐based muffin formulations were made with CF alone and with added biopolymers [whey protein (WP), xanthan gum (XG) and inulin (INL)] to evaluate their suitability to be a wheat flour (WF) substitute in muffins. Structural characteristics of the batters and muffins were studied by means of rheometry, microscopy, physicochemical properties, and texture and sensory analysis. Partial replacement of CF with XG, alone (at 0.5 and 1%) or blended with either WP or INL, significantly increased the batter viscoelasticity as denser matrices developed; moreover, the muffins with XG added at 1% had similar hardness to wheat gluten muffins. The replacement of WF decreased the springiness, cohesiveness, chewiness, resilience and specific volume of the muffin. However, baked muffins with added XG also showed higher sensory sponginess and moisture associated with numerous air bubbles in the batter and were perceived to be easier to swallow and to have better general appearance. 相似文献
122.
Maria do Socorro M. Rufino Jara Pérez‐Jiménez María Tabernero Ricardo E. Alves Edy S. De Brito Fulgencio Saura‐Calixto 《International Journal of Food Science & Technology》2010,45(11):2227-2233
Several tropical fruits have been described as natural sources of dietary fibre (DF) and phenolic compounds, associated with different health effects. The aim of this work was to ascertain the DF, phenolic compounds content (including non‐extractable polyphenols, mostly associated with DF) and antioxidant capacity in acerola fruits and cashew apples from selected clones. ‘BRS 236’ acerola fruits presented a high antioxidant capacity because of the combination of both extractable polyphenols and l ‐ascorbic acid (providing together a Folin value of 170 kg?1 g d.m.). ‘CCP 76’ cashew apples contained 28 g kg?1 d.m. of extractable polyphenols and 13 g kg?1 d.m. of ascorbic acid as well as a high amount of non‐extractable condensed tannins (52 g kg?1 d.m.). DF content was of 260 g kg?1 d.m. in acerola fruit and of 209 g kg?1 d.m. in cashew apple. Acerola fruits and cashew apple should therefore be considered as new natural sources of DF and phenolic compounds. 相似文献
123.
J.M. Veenstra A.M. Duncan C.N. Cryne B.R. Deschambault J.I. Boye M. Benali M. Marcotte S.M. Tosh E.R. Farnworth A.J. Wright 《Food research international (Ottawa, Ont.)》2010,43(2):553-559
Despite their demonstrated health benefits, consumption of pulses in Western societies has traditionally been low. This is, in part, due to the perception that pulses cause flatulence and gastrointestinal upset. This randomized, double-blind placebo-controlled, cross-over study assessed the impact of 28 consecutive days consumption of 100 g dry weight Kabuli chickpeas, green Laird lentils, and green peas, in comparison to a potato control, on perceived flatulence, abdominal comfort, bowel movements and overall gastrointestinal function using a questionnaire with yes/no and visual analog rankings, in 21 healthy males between the ages of 19–40. Questionnaires were completed during three phases (PRE, EARLY, LATE) of each treatment period. Chi-square (occurrence) and Wilcoxon test (severity rank) analyses revealed minor changes in occurrence and/or severity of flatulence and abdominal comfort, but no changes in overall gastrointestinal function. These results demonstrate that pulses containing oligosaccharides are well tolerated with negligible perceived changes in flatulence and overall gastrointestinal function when incorporated into the diet of healthy adult males. 相似文献
124.
Niina MM Saviranta Mikko J Anttonen Atte von Wright Reijo O Karjalainen 《Journal of the science of food and agriculture》2008,88(1):125-132
BACKGROUND: Red clover (Trifolium pratense L.), a widely used fodder, has recently received considerable interest as a valuable source of isoflavones for many health‐related applications. The aim of this study was to analyse the concentrations of four isoflavones, daidzein, genistein, formononetin and biochanin A, in extracts of leaves, stems, roots and different coloured flowers from red clover by high‐performance liquid chromatography and to determine the antifungal activities of the extracts. RESULTS: Among greenhouse‐grown samples the highest amounts of daidzein and genistein were found in petioles (0.11–0.28 and 0.30–0.54 mg g?1 respectively), while leaves were rich in formononetin and biochanin A (5.57–9.05 and 10.94–14.59 mg g?1 respectively). High formononetin concentrations were found in roots, but very little biochanin A. Among field‐grown samples the highest concentrations of daidzein and genistein were detected in stems collected in August (0.24 and 0.55 mg g?1 respectively), while the highest amounts of formononetin and biochanin A were found in young leaves collected in June (7.47 and 9.69 mg g?1 respectively). Most of the extracts inhibited the growth of Drechslera teres, while the root extract showed the strongest effect against Microdochium nivale. CONCLUSION: High levels of bioactive compounds found not only in inflorescences but also in roots, leaves and stems suggest that red clover may be an inexpensive and valuable resource for many applications. Copyright © 2007 Society of Chemical Industry 相似文献
125.
William E. Wright 《Acta Informatica》1980,15(1):3-17
Summary Binary search trees are shown to be reasonable alternatives to multiway trees for files stored in magnetic bubble memory. An algorithm for maintaining AVL trees is shown to be by far the most efficient of eight algorithms considered, when applied to secondary memory. A simplified model for analyzing the AVL algorithm is developed. A practical AVL algorithm for secondary memory is presented. Simulation results showing the performance of the AVL algorithm and a basic nonbalancing algorithm are given. 相似文献
126.
Factors influencing the national distribution of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in British soils 总被引:5,自引:0,他引:5
Heywood E Wright J Wienburg CL Black HI Long SM Osborn D Spurgeon DJ 《Environmental science & technology》2006,40(24):7629-7635
The polycyclic aromatic hydrocarbons (PAHs) naphthalene, acenaphthylene, acenaphthene, fluorene, fluoranthene, pyrene, benzo[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, ideno[1,2,3,-cd]-pyrene, dibenz[a,h]anthracene, benzo[g,h,i]perylene and the polychlorinated biphenyls (PCBs) 8, 18, 28, 29, 31, 52, 77, 101, 105, 114, 118, 123, 126, 128, 138, 141, 149, 153, 156, 157, 163, 169, 170, 171, 180, 183, 187, 189, 194, 199, 201, 206, and 209 were measured in -200 rural soils across Great Britain (GB). Dominance of soil PAH profiles by heavier compounds (4-6 rings) provided initial evidence for the importance of source in governing soil PAH concentrations. No relationship was found between soil organic matter (SOM) and sum concentration of total and "heavy" PAHs, although there was a weak positive relationship with lighter compounds. A spatial statistical technique showed that highest soil PAH concentrations were usually found close to industrial/urban centers where presumably source intensity is highest. PCBs clustered into seven groups, five of which contained a single "dioxin like" PCB, one contained lighter congeners (2-4 chlorines), and one contained heavy congeners (5-10 chlorines). Linear regressions with SOM explained up to 24.3% of variation for the sum concentration of penta- to deca- congeners, but <1% for the lighter congener groups. No significant relationships were found with latitude. Spatial statistical techniques showed clusters of high soil PCB concentrations predominantly in west and south east GB, either associated with urbanized areas or on the West coast. 相似文献
127.
M. A. Martínez-Anaya Teresa Jiménez 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1997,205(3):209-214
Nine commercial enzyme preparations and two laboratory-designed mixes with amylase and/or pentosanase/xylanase activity were
used to prepare bread samples, and the effects on bread quality and keeping properties were determined. With the doses added,
enzymes significantly shortened fermentation time without affecting the pH or the machinability of the doughs. Bread with
an improved volume, a greater intensity of aroma and a softer texture was obtained. Loaves had a less intense and characteristic
taste and, in some cases, an uneven grain. All enzymes delayed bread firming, but rates varied with each preparation. Factor
analysis classified bread samples according to their composition and source.
Received:7 November 1996/Revised version: 21 January 1997 相似文献
128.
Long-term trends and opportunities for managing regional water supply and wastewater greenhouse gas emissions 总被引:2,自引:0,他引:2
Greenhouse gas emissions are likely to rise faster than growth in population and more than double for water supply and wastewater services over the next 50 years in South East Queensland (SEQ), Australia. New sources of water supply such as rainwater tanks, recycled water, and desalination currently have greater energy intensity than traditional sources. In addition, direct greenhouse gas emissions from reservoirs and wastewater treatment and handling have potentially the same magnitude as emissions from the use of energy. Centralized and decentralized water supply and wastewater systems are considered for a scenario based upon a government water supply strategy for the next 50 years. Many sources of data have large uncertainties which are estimated following the IPCC Good Practice Guidelines. Important sources of emissions with large uncertainties such as rainwater tanks and direct emissions were identified for further research and potential mitigation of greenhouse gas emissions. 相似文献
129.
The gas-phase kinetic coefficients of OH radicals with two primary fluorinated alcohols, CF(3)CH(2)CH(2)OH (k(1)) and CF(3)(CH(2))(2)CH(2)OH (k(2)), potential replacements of hydrofluorocarbons (HFCs), are reported here as a function of temperature (T = 263-358 K) for the first time. k(1) and k(2) (together referred as k(i)) were measured under pseudo-first-order conditions with respect to the initial OH concentration using the pulsed laser photolysis/laser induced fluorescence technique. The observed temperature dependence of k(i) (in cm(3) molecule(-1) s(-1)) is described by the following Arrhenius expressions: k(1)(T) = (2.82 ± 1.28) × 10(-12) exp{-(302 ± 139)/T} cm(3) molecule(-1) s(-1) and k(2)(T) = (1.20 ± 0.73) × 10(-11) exp{-(425 ± 188)/T} cm(3) molecule(-1) s(-1).The uncertainties in the Arrhenius parameters are at a 95% confidence level (± 2σ). Uncertainties in k(i)(T) include both statistical and systematic errors. Activation energies were (2.5 ± 1.2) kJ/mol and (3.6 ± 1.6) kJ/mol for the OH-reaction with CF(3)CH(2)CH(2)OH and CF(3)(CH(2))(2)CH(2)OH, respectively. The global lifetime (τ) at 275 K for CF(3)CH(2)CH(2)OH and CF(3)(CH(2))(2)CH(2)OH due to the OH-reaction was estimated to be ca. 2 weeks and 5 days, respectively. The reported Arrhenius parameters can be used in 3D models that take into account the geographical region and season of emissions for estimating a matrix of instantaneous lifetimes. As a consequence of the substitution of the -CH(3) group by a -CH(2)OH group in HFCs, such as CF(3)CH(2)CH(3) and CF(3)(CH(2))(2)CH(3), the tropospheric lifetime with respect to the OH reaction is significantly shorter and, since their radiative forcing is similar, global warming potentials of CF(3)CH(2)CH(2)OH and CF(3)(CH(2))(2)CH(2)OH are negligible. Therefore, CF(3)CH(2)CH(2)OH and CF(3)(CH(2))(2)CH(2)OH seem to be suitable alternatives to HFCs. 相似文献
130.
Physical, chemical, sensory and processing properties of milk produced by feeding a rumen-undegradable fish meal protein supplement to Holstein cows were investigated. The supplement contained (as fed basis) 25% soft-white wheat, 60% herring meal, and 15% feather meal. The total fat level in the milk decreased to 2.43%. For both pasteurized and ultra-high temperature processed drinking milk, no difference was found between fish meal (FM) milk and control milk in terms of color, flavor and flavor stability; in particular, no oxidized flavor was observed. Cheddar cheese made from FM milk ripened faster after 3 mo of ripening and developed a more desirable texture and stronger Cheddar flavor. The yield efficiencies for FM and control cheese, 94.4 (+/- 2.44 SE) and 96.4 (+/- 2.26 SE), respectively, were not different. Relative to controls, average fat globule size was smaller in FM milk and churning time of FM cream was longer. FM butter had softer texture and better cold spreadability, and butter oils from FM enriched milk had lower dropping points compared to control butter oil (average 32.89 versus 34.06 degrees C). These differences in physical properties of butter fat were greater than expected considering that iodine values were not different. This study demonstrates the feasibility of producing high quality products from milk naturally supplemented with FM, but the results also show that dietary changes affect processing properties. 相似文献