全文获取类型
收费全文 | 464篇 |
免费 | 14篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 7篇 |
综合类 | 1篇 |
化学工业 | 106篇 |
金属工艺 | 6篇 |
机械仪表 | 14篇 |
建筑科学 | 16篇 |
矿业工程 | 1篇 |
能源动力 | 5篇 |
轻工业 | 26篇 |
水利工程 | 9篇 |
无线电 | 48篇 |
一般工业技术 | 71篇 |
冶金工业 | 102篇 |
原子能技术 | 5篇 |
自动化技术 | 62篇 |
出版年
2023年 | 3篇 |
2022年 | 21篇 |
2021年 | 28篇 |
2020年 | 3篇 |
2019年 | 10篇 |
2018年 | 7篇 |
2017年 | 4篇 |
2016年 | 13篇 |
2015年 | 10篇 |
2014年 | 19篇 |
2013年 | 18篇 |
2012年 | 16篇 |
2011年 | 21篇 |
2010年 | 13篇 |
2009年 | 20篇 |
2008年 | 16篇 |
2007年 | 18篇 |
2006年 | 17篇 |
2005年 | 11篇 |
2004年 | 17篇 |
2003年 | 11篇 |
2002年 | 11篇 |
2001年 | 7篇 |
2000年 | 4篇 |
1999年 | 9篇 |
1998年 | 38篇 |
1997年 | 14篇 |
1996年 | 9篇 |
1995年 | 14篇 |
1994年 | 8篇 |
1993年 | 8篇 |
1992年 | 10篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1985年 | 1篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1972年 | 2篇 |
1971年 | 3篇 |
排序方式: 共有479条查询结果,搜索用时 15 毫秒
21.
Márk Juhász Viktor L. Nagy Hajnal Székely Dorottya Kocsis Zsolt Tulassay János F. László 《Journal of the Royal Society Interface》2014,11(98)
This pilot study was devoted to the effect of static magnetic field (SMF)-exposure on erosive gastritis. The randomized, self- and placebo-controlled, double-blind, pilot study included 16 patients of the 2nd Department of Internal Medicine, Semmelweis University diagnosed with erosive gastritis. The instrumental analysis followed a qualitative (pre-intervention) assessment of the symptoms by the patient: lower heartburn (in the ventricle), upper heartburn (in the oesophagus), epigastric pain, regurgitation, bloating and dry cough. Medical diagnosis included a double-line upper panendoscopy followed by 30 min local inhomogeneous SMF-exposure intervention at the lower sternal region over the stomach with peak-to-peak magnetic induction of 3 mT and 30 mT m−1 gradient at the target site. A qualitative (post-intervention) assessment of the same symptoms closed the examination. Sham- or SMF-exposure was used in a double-blind manner. The authors succeeded in justifying the clinically and statistically significant beneficial effect of the SMF- over sham-exposure on the symptoms of erosive gastritis, the average effect of inhibition was 56% by p = 0.001, n = 42 + 96. This pilot study was aimed to encourage gastroenterologists to test local, inhomogeneous SMF-exposure on erosive gastritis patients, so this intervention may become an evidence-based alternative or complementary method in the clinical use especially in cases when conventional therapy options are contraindicated. 相似文献
22.
23.
Emese Rka Blint Gabriella Fr Balzs Kui Zsolt Balla Eszter Sra Kormnyos Erik Mrk Orjn Brigitta Tth Gyngyi Horvth Edina Szcs Sndor Benyhe Eszter Ducza Petra Pallagi Jzsef Malth Viktria Venglovecz Pter Hegyi Lrnd Kiss Zoltn Rakonczay Jr. 《International journal of molecular sciences》2022,23(3)
Opioids are widely used for the pain management of acute pancreatitis (AP), but their impact on disease progression is unclear. Therefore, our aim was to study the effects of clinically relevant opioids on the severity of experimental AP. Various doses of fentanyl, morphine, or buprenorphine were administered as pre- and/or post-treatments in rats. Necrotizing AP was induced by the intraperitoneal injection of L-ornithine-HCl or intra-ductal injection of Na-taurocholate, while intraperitoneal caerulein administration caused edematous AP. Disease severity was determined by laboratory and histological measurements. Mu opioid receptor (MOR) expression and function was assessed in control and AP animals. MOR was expressed in both the pancreas and brain. The pancreatic expression and function of MOR were reduced in AP. Fentanyl post-treatment reduced necrotizing AP severity, whereas pre-treatment exacerbated it. Fentanyl did not affect the outcome of edematous AP. Morphine decreased vacuolization in edematous AP, while buprenorphine pre-treatment increased pancreatic edema during AP. The overall effects of morphine on disease severity were negligible. In conclusion, the type, dosing, administration route, and timing of opioid treatment can influence the effects of opioids on AP severity. Fentanyl post-treatment proved to be beneficial in AP. Clinical studies are needed to determine which opioids are best in AP. 相似文献
24.
Karla Blau O. Kovacs Gerlinde Lauterbach M. Makhoul W. Pritzkow Tieu Dung Tien 《Advanced Synthesis \u0026amp; Catalysis》1989,331(5):771-777
Chromium stearate and chromium acetylacetonate are very active catalysts both for the oxidation of hydrocarbons by molecular oxygen and for the decomposition of organic hydroperoxides. During these reactions they also catalyze the oxidation of secondary alcohols to the corresponding ketones by organic hydroperoxides. From organic hydroperoxides and chromium(III)compounds chromium (VI) compounds are formed which are probably the effective agents oxidizing secondary alcohols to ketones. 相似文献
25.
Dra Szab Zsolt Srszegi Beta Polgr va Sghy Dra Regldi Tünde Tth Zsfia Ondi Przemyslaw Leszek Zoltn V. Varga Zsuzsanna Helyes gnes Kemny Pter Ferdinandy Andrea Tams 《International journal of molecular sciences》2022,23(7)
Pituitary adenylate cyclase activating polypeptide-38 (PACAP-38) is a multifunctional neuropeptide, which may play a role in cardioprotection. However, little is known about the presence of PACAP-38 in heart failure (HF) patients. The aim of our study was to measure the alterations of PACAP-38 like immunoreactivity (LI) in acute (n = 13) and chronic HF (n = 33) and to examine potential correlations between PACAP-38 and HF predictors (cytokines, NT-proBNP). Tissue PACAP-38 LI and PAC1 receptor levels were also investigated in heart tissue samples of patients with HF. Significantly higher plasma PACAP-38 LI was detected in patients with acute HF, while in chronic HF patients, a lower level of immunoreactivity was observed compared to healthy controls (n = 13). Strong negative correlation was identified between plasma PACAP-38 and NT-proBNP levels in chronic HF, as opposed to the positive connection seen in the acute HF group. Plasma IL-1 β, IL-2 and IL-4 levels were significantly lower in chronic HF, and IL-10 was significantly higher in patients with acute HF. PACAP-38 levels of myocardial tissues were lower in all end-stage HF patients and lower PAC1 receptor levels were detected in the primary dilated cardiomyopathy group compared to the controls. We conclude that PACAP-38 and PAC1 expression correlates with some biomarkers of acute and chronic HF; therefore, further studies are necessary to explore whether PACAP could be a suitable prognostic biomarker in HF patients. 相似文献
26.
Estimation of the costs of acute gastrointestinal illness in British Columbia, Canada 总被引:1,自引:0,他引:1
Henson SJ Majowicz SE Masakure O Sockett PN MacDougall L Edge VL Thomas MK Fyfe M Kovacs SJ Jones AQ 《International journal of food microbiology》2008,127(1-2):43-52
The costs associated with gastrointestinal infection (GI) in the province of British Columbia, Canada, were estimated using data from a population-based survey in three health service delivery areas, namely Vancouver, East Kootenay and Northern Interior. The number of cases of disease, consequent expenditure of resources and associated economic costs were modeled as probability distributions in a stochastic model. Using 2004 prices, the estimated mean annual cost per capita of gastrointestinal infection was CAN$128.61 (euro207.96), with a mean annual cost per case of CAN$1,342.57 (euro2,170.99). The mean estimate of the overall economic burden to British Columbia was CAN$514.2 million (euro831.5 million) (95% CFI CAN$161.0 million to CAN$5.8 billion; euro260.3 million to euro9.38 billion). The major element of this cost was the loss of productivity associated with time away from paid employment by both the sick and their caregivers. Sensitivity analysis suggested that the uncertainty associated with the base model assumptions did not significantly affect the estimates. The results are comparable to those obtained in an earlier study using a similar analytical framework and data from the city of Hamilton, Ontario, Canada. 相似文献
27.
Kovacs Attila J.; Mühlbauer Thomas; Shea Charles H. 《Canadian Metallurgical Quarterly》2009,35(2):390
Three experiments utilizing a 14-element arm movement sequence were designed to determine if reinstating the visual–spatial coordinates, which require movements to the same spatial locations utilized during acquisition, results in better effector transfer than reinstating the motor coordinates, which require the same pattern of homologous muscle activation. Results demonstrated better transfer when visual–spatial coordinates were reinstated than when motor coordinates where reinstated regardless of the amount of practice (1, 4, or 12 days; Experiments 1–3, respectively). Transfer (left to right and right to left) was symmetric when visual–spatial coordinates were reinstated but not when motor coordinates were reinstated. When motor coordinates were reinstated after 12 days of practice and vision occluded, transfer was better from right limb to left than vice versa. The data are also consistent with the notion that multiple codes (visual, spatial, and motor) are developed over practice, with each contributing to transfer performance when the respective coordinates are reinstated. Further, the results indicate a disruption of the linkage (concatenation) between subsequences when one or more coordinates are changed on the transfer test. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
28.
29.
Jungwirth M Pöcksteiner N Kovacs G Weigel R 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2002,49(4):519-527
Using the planar waveguide concept in surface acoustic wave (SAW) technology is often advantageous when the modeling of transversely distributed phenomena is indispensable for an accurate design of SAW devices. This is especially true when complex multi-track structures such as transversely coupled resonator filters (TCRFs) are under consideration where, e.g., transverse velocity and stiffness profiles have to be incorporated in the device simulation. The interdigital transducers (IDTs) and the reflector gratings composing those devices behave as planar waveguides, supporting, in principle, all kinds of modes such as bound, semi-bound, and radiation modes. Therefore, to model these SAW propagation effects, we subdivide the SAW structures in transverse direction into several parallel waveguiding channels (N regions), and take, as the wave-describing quantity, a two-dimensional scalar potential function. By doing so, we obtain a complete set of orthonormal modes into which an arbitrary transverse excitation function can be expanded to study its propagation. The general mode spectrum includes a discrete spectrum of bound modes and continuous spectra of semi-bound and radiation modes. We calculate all types of modes by making use of the stack matrix technique. The present work, which arose from the requirement of creating an efficient mathematical tool for the simulation of TCRFs, provides the complete analysis of general SAW multi-channel structures. 相似文献
30.
Bozoki Z Mohacsi A Szabo G Bor Z Erdelyi M Chen W Tittel FK 《Applied spectroscopy》2002,56(6):715-719
A photoacoustic spectroscopic (PAS) and a direct optical absorption spectroscopic (OAS) gas sensor, both using continuous-wave room-temperature diode lasers operating at 1531.8 nm, were compared on the basis of ammonia detection. Excellent linear correlation between the detector signals of the two systems was found. Although the physical properties and the mode of operation of both sensors were significantly different, their performances were found to be remarkably similar, with a sub-ppm level minimum detectable concentration of ammonia and a fast response time in the range of a few minutes. 相似文献