全文获取类型
收费全文 | 2759篇 |
免费 | 180篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 19篇 |
综合类 | 1篇 |
化学工业 | 595篇 |
金属工艺 | 28篇 |
机械仪表 | 42篇 |
建筑科学 | 91篇 |
矿业工程 | 2篇 |
能源动力 | 116篇 |
轻工业 | 560篇 |
水利工程 | 26篇 |
石油天然气 | 9篇 |
无线电 | 206篇 |
一般工业技术 | 433篇 |
冶金工业 | 231篇 |
原子能技术 | 26篇 |
自动化技术 | 555篇 |
出版年
2024年 | 6篇 |
2023年 | 32篇 |
2022年 | 122篇 |
2021年 | 110篇 |
2020年 | 65篇 |
2019年 | 99篇 |
2018年 | 118篇 |
2017年 | 106篇 |
2016年 | 108篇 |
2015年 | 85篇 |
2014年 | 135篇 |
2013年 | 197篇 |
2012年 | 183篇 |
2011年 | 229篇 |
2010年 | 160篇 |
2009年 | 132篇 |
2008年 | 134篇 |
2007年 | 117篇 |
2006年 | 110篇 |
2005年 | 77篇 |
2004年 | 70篇 |
2003年 | 63篇 |
2002年 | 50篇 |
2001年 | 21篇 |
2000年 | 25篇 |
1999年 | 40篇 |
1998年 | 88篇 |
1997年 | 64篇 |
1996年 | 39篇 |
1995年 | 29篇 |
1994年 | 22篇 |
1993年 | 13篇 |
1992年 | 7篇 |
1991年 | 13篇 |
1990年 | 6篇 |
1989年 | 12篇 |
1988年 | 15篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有2940条查询结果,搜索用时 15 毫秒
81.
Alberto E. León Gabriela N. Barrera Gabriela T. Pérez Pablo D. Ribotta Cristina M. Rosell 《European Food Research and Technology》2006,224(2):187-192
The effect of the amount of damaged starch in two different flours (wheat and triticale) on the bread quality and its behaviour during storage has been analysed. Two wheat and one triticale flour cultivars were milled in a disc mill to obtain different levels of damaged starch. Differential Scanning Calorimetry (DSC) and Rapid Visco Analyser (RVA) were used to characterize the flour properties and TA-XT2 textural analyses were made on breadcrumb. The effect of the damaged starch content on the bread firming, the amylopectin retrogradation and starch-pasting properties were studied in order to establish any relationship between damaged starch and bread staling. DSC analysis showed that the damaged starch content changed the thermal behaviour of flour–water mixtures: the higher the levels of damaged starch the lower the starch-gelatinization enthalpy and the higher the melting enthalpy of amylose–lipid complexes. The amount of amylopectin retrogradation and breadcrumb firming increased with the damaged starch content at the beginning of storage time; however, differences were decreasing at final storage time. The flour viscosity during pasting decreased as their damaged starch content increased. 相似文献
82.
The thermodynamic properties of food as a function of pressure and temperature are essential for modeling high-pressure processes. Sound velocity measurements in liquids at high pressure conditions are particularly interesting because they allow for deriving other properties such as the specific heat capacity or thermal expansion coefficient which are difficult to measure. By other means, in this work, the sound velocity was measured in tomato paste at high pressures with a purposed designed acoustic cell. The measurements were made in a wide range of pressures and temperatures from 0.1 to 350 MPa and from 0 to 50 °C, respectively. The sound velocity was directly measured with an accuracy of 0.1% using the transmission technique with piezoelectrics operating at 2 MHz. Thereafter, the isentropic compressibility coefficient of tomato paste was calculated from experimental data. Specific heat capacity and thermal expansion coefficient were also obtained through a software algorithm. 相似文献
83.
S.K. Kvidera M.J. Dickson M. Abuajamieh D.B. Snider M. V. Sanz Fernandez J.S. Johnson A.F. Keating P.J. Gorden H.B. Green K.M. Schoenberg L.H. Baumgard 《Journal of dairy science》2017,100(5):4113-4127
Study objectives were to evaluate the effects of intentionally reduced intestinal barrier function on productivity, metabolism, and inflammatory indices in otherwise healthy dairy cows. Fourteen lactating Holstein cows (parity 2.6 ± 0.3; 117 ± 18 d in milk) were enrolled in 2 experimental periods. Period 1 (5 d) served as the baseline for period 2 (7 d), during which cows received 1 of 2 i.v. treatments twice per day: sterile saline or a gamma-secretase inhibitor (GSI; 1.5 mg/kg of body weight). Gamma-secretase inhibitors reduce intestinal barrier function by inhibiting crypt cell differentiation into absorptive enterocytes. During period 2, control cows receiving sterile saline were pair-fed (PF) to the GSI-treated cows, and all cows were killed at the end of period 2. Administering GSI increased goblet cell area 218, 70, and 28% in jejunum, ileum, and colon, respectively. In the jejunum, GSI-treated cows had increased crypt depth and reduced villus height, villus height-to-crypt depth ratio, cell proliferation, and mucosal surface area. Plasma lipopolysaccharide binding protein increased with time, and tended to be increased 42% in GSI-treated cows relative to PF controls on d 5 to 7. Circulating haptoglobin and serum amyloid A concentrations increased (585- and 4.4-fold, respectively) similarly in both treatments. Administering GSI progressively reduced dry matter intake (66%) and, by design, the pattern and magnitude of decreased nutrient intake was similar in PF controls. A similar progressive decrease (42%) in milk yield occurred in both treatments, but we observed no treatment effects on milk components. Cows treated with GSI tended to have increased plasma insulin (68%) and decreased circulating nonesterified fatty acids (29%) compared with PF cows. For both treatments, plasma glucose decreased with time while β-hydroxybutyrate progressively increased. Liver triglycerides increased 221% from period 1 to sacrifice in both treatments. No differences were detected in liver weight, liver moisture, or body weight change. Intentionally compromising intestinal barrier function caused inflammation, altered metabolism, and markedly reduced feed intake and milk yield. Further, we demonstrated that progressive feed reduction appeared to cause leaky gut and inflammation. 相似文献
84.
85.
86.
Mark F. Pittenger Saman Eghtesad Pablo G. Sanchez Xiaoyan Liu Zhongjun Wu Ling Chen Bartley P. Griffith 《International journal of molecular sciences》2022,23(2)
Many clinical studies utilizing MSCs (mesenchymal stem cells, mesenchymal stromal cells, or multipotential stromal cells) are underway in multiple clinical settings; however, the ideal approach to prepare these cells in vitro and to deliver them to injury sites in vivo with maximal effectiveness remains a challenge. Here, pretreating MSCs with agents that block the apoptotic pathways were compared with untreated MSCs. The treatment effects were evaluated in the myocardial infarct setting following direct injection, and physiological parameters were examined at 4 weeks post-infarct in a rat permanent ligation model. The prosurvival treated MSCs were detected in the hearts in greater abundance at 1 week and 4 weeks than the untreated MSCs. The untreated MSCs improved ejection fraction in infarcted hearts from 61% to 77% and the prosurvival treated MSCs further improved ejection fraction to 83% of normal. The untreated MSCs improved fractional shortening in the infarcted heart from 52% to 68%, and the prosurvival treated MSCs further improved fractional shortening to 77% of normal. Further improvements in survival of the MSC dose seems possible. Thus, pretreating MSCs for improved in vivo survival has implications for MSC-based cardiac therapies and in other indications where improved cell survival may improve effectiveness. 相似文献
87.
The ability of five strains of different bifidobacterial species (Bifidobacterium animalis, B. bifidum, B. infantis, B. longum, B. pseudolongum) isolated from human and animal gut to degrade myo-inositol hexaphosphate or phytic acid (InsP(6)) has been evaluated. The disappearance of phytate and the generation of lower myo-inositol phosphates were determined in a complex medium in which phytic acid was the only source of phosphorus. Bifidobacterium infantis ATCC 15697 showed the highest level of phytate-degrading activity. This strain displayed optimal activity at slight acid pH (6.0-6.5) and 50 degrees C, but also retained high activity levels at neutral pH and 37 degrees C. B. infantis ATCC 15697 produced maximum activity during the stationary phase of growth and when 1% lactose was used as carbon source. In contrast, the presence of inorganic phosphate in the growth medium inhibited phytase activity. The ability of B. infantis ATCC 15697 to generate lower myo-inositol phosphates and, particularly, accumulate myo-inositol tri-phosphates (InsP(3)) from partial hydrolysis of InsP(6) could contribute to the reduction of the anti-nutritional properties of InsP(6) and the generation of intermediate compounds with beneficial properties during food processing and gastrointestinal transit. 相似文献
88.
Sorption of Th(IV) onto two-line ferrihydrite and magnetite in NaClO4 solutions has been studied as a function of pH and ionic strength revealing that sorption onto both solids increases with pH while it is independent on ionic strength. Sorption capacity of both solids is high, the maximum sorption (almost 100% of Th(IV)) occurs at pH higher than 3.5 for ferrihydrite, and higher than 3.0 for magnetite. Sorption variation with pH was modeled with three different models using the FITEQL 4.0 code: non-electrostatic model, constant capacitance model, and diffuse-double layer model. In all cases, good fit to the experimental data is obtained with one-species: a corner-sharing bidentate-mononuclear surface complex, (FeO)2Th2+, which coincides with the surface complex postulated on these solids surface in previous spectroscopic studies; however, the monodentate species FeOThOH2+ also gives a satisfactory fit. Under the experimental conditions of the present study, any effect of possible thorium colloid formation is negligible. 相似文献
89.
Cano José-Carlos Cuenca Javier Giménez Domingo Saura-Sánchez Mariano Segado-Cabezos Pablo 《The Journal of supercomputing》2019,75(3):1368-1381
The Journal of Supercomputing - Multibody systems consist of a set of components connected through some joints, where the movement of the system is determined by those of its components. Their... 相似文献
90.
The present research introduces a new mechanism by which emotion can affect evaluation. On the basis of the self-validation hypothesis (R. E. Petty, P. Bri?ol, & Z. L. Tormala, see record 2002-12575-003), the authors predicted and found that emotion can influence evaluative judgments by affecting the confidence people have in their thoughts to a persuasive message. In each study, participants first read a strong or weak persuasive communication. After listing their thoughts about the message, participants were induced to feel happy or sad. Relative to sad participants, those put in a happy state reported more thought confidence. As a consequence, the effect of argument quality on attitudes was greater for happy than for sad participants. These self-validation effects generalized across different emotion inductions, different persuasion topics, and different measures of thought confidence. In one study, happy and sad conditions each differed from a neutral affect control. Most important, these metacognitive effects of emotion only occurred under high elaboration conditions. In contrast, individuals with relatively low motivation to think showed a main effect of emotion on attitudes, regardless of argument quality. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献