全文获取类型
收费全文 | 4416篇 |
免费 | 102篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 21篇 |
综合类 | 11篇 |
化学工业 | 433篇 |
金属工艺 | 50篇 |
机械仪表 | 49篇 |
建筑科学 | 91篇 |
矿业工程 | 8篇 |
能源动力 | 57篇 |
轻工业 | 124篇 |
水利工程 | 4篇 |
石油天然气 | 7篇 |
无线电 | 141篇 |
一般工业技术 | 407篇 |
冶金工业 | 2738篇 |
原子能技术 | 15篇 |
自动化技术 | 365篇 |
出版年
2023年 | 21篇 |
2022年 | 26篇 |
2021年 | 67篇 |
2020年 | 50篇 |
2019年 | 56篇 |
2018年 | 50篇 |
2017年 | 40篇 |
2016年 | 63篇 |
2015年 | 53篇 |
2014年 | 54篇 |
2013年 | 128篇 |
2012年 | 97篇 |
2011年 | 137篇 |
2010年 | 97篇 |
2009年 | 90篇 |
2008年 | 104篇 |
2007年 | 111篇 |
2006年 | 77篇 |
2005年 | 67篇 |
2004年 | 50篇 |
2003年 | 57篇 |
2002年 | 51篇 |
2001年 | 38篇 |
2000年 | 26篇 |
1999年 | 111篇 |
1998年 | 769篇 |
1997年 | 440篇 |
1996年 | 295篇 |
1995年 | 184篇 |
1994年 | 161篇 |
1993年 | 173篇 |
1992年 | 49篇 |
1991年 | 49篇 |
1990年 | 57篇 |
1989年 | 82篇 |
1988年 | 54篇 |
1987年 | 58篇 |
1986年 | 37篇 |
1985年 | 27篇 |
1984年 | 11篇 |
1983年 | 16篇 |
1982年 | 23篇 |
1981年 | 17篇 |
1980年 | 28篇 |
1979年 | 13篇 |
1978年 | 18篇 |
1977年 | 62篇 |
1976年 | 133篇 |
1975年 | 6篇 |
1971年 | 6篇 |
排序方式: 共有4521条查询结果,搜索用时 15 毫秒
1.
Marcus Reppich Zdeněk Jegla Jakob Grondinger Yaovi Ouézou Azouma Vojtěch Turek 《化学,工程师,技术》2021,93(10):1581-1589
This study investigates the behavior of fruit and vegetable samples during drying. The experimental data are fitted to several different thin-layer drying models. Regression analysis is used to determine model parameters, while statistical indicators serve to evaluate the goodness of fit. The power function model gives the best fit for all examined samples. Based on this model, different drying and heat storage technologies can be combined to ensure that the required residual moisture content of an agricultural product is reached. It is demonstrated on the case of a specific Togolese processing plant that under favorable conditions, fossil fuel consumption can be decreased by 33 %. 相似文献
2.
Marcus Heinze Sandra Starke Marcel Händler Hartmut Komber Marco Drache Norbert Moszner Brigitte Voit Doris Pospiech 《应用聚合物科学杂志》2019,136(48):48256
We demonstrate in this study that the combination of modern inline monitoring methods [here: inline nuclear magnetic resonance (NMR)] with simulations gains more exact and profound kinetic results than previously used methods like linearization without that combination. The 1H-NMR spectroscopic data (more than 100 data points) are used to construct the copolymerization diagram. The reactivity ratios are obtained applying the van Herks nonlinear least square method. The examination of the radical copolymerization of 2-hydroxyethyl methacrylate (HEMA) with (2-{[2-(ethoxycarbonyl)prop-2-en-1-yl]oxy}ethyl) phosphonic acid (ECPPA) as important adhesive monomer used in dentistry yields reactivity ratios of rHEMA = 1.83; rECPPA = 0.42. The copolymerization diagram reflects nonideal, non-azeotropic copolymerization. The sequence distribution of the obtained by Monte Carlo simulation indicates the generation of statistical copolymers. As an important finding, it is demonstrated that the repeating units responsible for etching and adhesion are arranged over the whole polymer chain, which is necessary to achieve proper functionality. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48256. 相似文献
3.
4.
Heng Zhang Jack Gromek Gayath W. Fernando Harris L. Marcus Sam Boorse 《Journal of Phase Equilibria》2002,23(3):246-248
The thermal equilibrium decomposition properties of the PdO-Pd system under oxygen partial pressures ranging from 0.1 to 1.0 atm in a total combined pressure of oxygen and nitrogen of 1.0 atm were investigated by means of thermal-gravimetric analyses. The phase diagram of Pd-PdO over the range of oxygen/nitrogen gas concentration was established. The decomposition temperature of PdO to Pd was found to increase with the partial pressure of oxygen. 相似文献
5.
6.
J Hibbert DC Howlett KL Greenwood LM MacDonald AJ Saunders 《Canadian Metallurgical Quarterly》1997,70(839):1191-1194
Renal vein thrombosis (RVT) is the most frequently occurring vascular condition in the new-born kidney. The predisposing factors include dehydration, sepsis, birth asphyxia, maternal diabetes, polycythaemia and the presence of an indwelling umbilical venous catheter. (RVT) may present clinically with a flank mass, haematuria, hypertension or renal failure. Many imaging modalities have been employed, but ultrasound is the technique most commonly used in the evaluation of neonates with suspected RVT. Thrombosis commences in the small renal veins and subsequently propagates via larger interlobar veins to the main renal vein and inferior vena cava (IVC). The ultrasound appearances depend upon the stage at which the examination is performed and extent of the thrombus. Initially, the interlobular and interlobar thrombus appears as highly echogenic streaks. These streaks commence in a peripheral, focal segment of the involved kidney and only persist for a few days. In the first week the affected kidney swells and becomes echogenic with prominent echopoor medullary pyramids. Later, the swelling increases and the kidney becomes heterogenous with loss of corticomedullary differentiation. Grey scale ultrasound readily demonstrates thrombus within the renal vein and IVC. Adrenal haemorrhage is a recognized association and may be identified ultrasonically. Colour Doppler scanning provides additional information. In the early stages of RVT, colour Doppler may demonstrate absent intrarenal and renal venous flow. Ultimately, the kidney may recover, show focal scarring or become atrophic. Thus, ultrasound provides an accessible and reliable tool in the assessment of suspected neonatal RVT. 相似文献
7.
DJ Conway MJ Holland RL Bailey AE Campbell OS Mahdi R Jennings E Mbena DC Mabey 《Canadian Metallurgical Quarterly》1997,65(3):1003-1006
Tumor necrosis factor alpha (TNF-alpha) may play a central role in the disease pathogenesis which occurs as a consequence of chlamydial infection. To investigate the importance of TNF-alpha gene promoter polymorphisms and TNF-alpha levels in tear fluid in scarring trachoma, a large matched-pair case-control study was performed in The Gambia. The -308A allele was present in a higher proportion of patients (28.4%) than controls (18.4%), with an increasing association for homozygotes (chi2 for trend, P = 0.032; allele frequency, 0.163 in patients and 0.099 in controls; chi2, P = 0.025). For the -238A allele, the association was similar but not significant. The disease association was highly significant when the number of either -308A or -238A sites in an individual was considered (P = 0.003). TNF-alpha promoter alleles are tightly linked to some HLA class I and II alleles, but multivariate analysis confirmed that the disease associations were independent of HLA, although a class I allele, A*6802, is also associated with disease. TNF-alpha was more frequently detected in tear samples from patients (27.6%) than from controls (15.9%), increasingly so for higher levels of detectable TNF-alpha (P = 0.015). Among patients, detectable TNF-alpha in tears was highly associated with the presence of ocular chlamydial infection (P < 0.001). The results indicate that TNF-alpha plays a major role in the tissue damage and scarring which occurs as a consequence of Chlamydia trachomatis infection. 相似文献
8.
9.
DC Reynolds CE Leak KK Bajaj CE Stutz RL Jones KR Evans PW Yu WM Theis 《Canadian Metallurgical Quarterly》1989,40(9):6210-6217
10.