全文获取类型
收费全文 | 932篇 |
免费 | 43篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 9篇 |
综合类 | 3篇 |
化学工业 | 100篇 |
金属工艺 | 11篇 |
机械仪表 | 40篇 |
建筑科学 | 47篇 |
能源动力 | 20篇 |
轻工业 | 73篇 |
水利工程 | 7篇 |
石油天然气 | 2篇 |
无线电 | 163篇 |
一般工业技术 | 186篇 |
冶金工业 | 200篇 |
原子能技术 | 4篇 |
自动化技术 | 121篇 |
出版年
2023年 | 4篇 |
2022年 | 7篇 |
2021年 | 7篇 |
2020年 | 7篇 |
2019年 | 4篇 |
2018年 | 18篇 |
2017年 | 13篇 |
2016年 | 14篇 |
2015年 | 12篇 |
2014年 | 25篇 |
2013年 | 55篇 |
2012年 | 30篇 |
2011年 | 40篇 |
2010年 | 33篇 |
2009年 | 33篇 |
2008年 | 33篇 |
2007年 | 45篇 |
2006年 | 42篇 |
2005年 | 22篇 |
2004年 | 37篇 |
2003年 | 35篇 |
2002年 | 35篇 |
2001年 | 24篇 |
2000年 | 21篇 |
1999年 | 31篇 |
1998年 | 72篇 |
1997年 | 58篇 |
1996年 | 35篇 |
1995年 | 23篇 |
1994年 | 17篇 |
1993年 | 19篇 |
1992年 | 17篇 |
1991年 | 17篇 |
1990年 | 8篇 |
1989年 | 7篇 |
1988年 | 9篇 |
1987年 | 3篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 8篇 |
1983年 | 8篇 |
1982年 | 9篇 |
1981年 | 6篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 10篇 |
1973年 | 2篇 |
1970年 | 2篇 |
排序方式: 共有986条查询结果,搜索用时 19 毫秒
101.
Electrophretic deposition (EPD) is a ceramic process. Although the kinetics for EPD have been established. However, there are still some ambiguities. In present study, a modified kinetic model was applied to describe the completely different behavior of EPD at −10 and −40 V respectively. The variation of the concentration profile during electrophoretical deposition at −10 and −40 V was simulated to explain what affected the EPD process. Based on the simulation, the depletion of colloidal particles near the electrode may be responsible for the EPD kinetic behaviors. 相似文献
102.
Germain M. Benie G.B. Boucher J.-M. Foucher S. Ko Fung Goita K. 《Geoscience and Remote Sensing, IEEE Transactions on》2003,41(8):1765-1772
Radar images can show great variability from pixel to pixel, which is an obstacle to effective processing. This variability, due to speckle created by the radar wave coherence, necessitates the use of more adapted filters. Previous studies have shown that multiresolution wavelet analysis yields better results but produces artefacts due to multiscale decomposition. This paper proposes a method that reduces these effects by introducing the fractal dimension. The resultant filter combines wavelet decomposition and variance change model based on the level of variance estimated by studying the fractal dimension of the image. 相似文献
103.
DE Sandberg MH MacGillivray RR Clopper C Fung L LeRoux DE Alliger 《Canadian Metallurgical Quarterly》1998,83(4):1134-1142
Several studies have investigated the quality of life (QOL) of GH-deficient (GHD) adults who, as children, had been treated with GH. Variable findings are probably related to sample heterogeneity and disparate research methodologies and designs, particularly the choice of control or comparison groups. In addition to comparing a relatively large sample to questionnaire norms, the present study is the first to compare the QOL adjustment of GHD patients to that of same sex siblings. A total of 140 former patients (76% of those eligible; mean age, 26 yr; n = 95 isolated GHD, n = 45 multiple pituitary hormone deficiencies; 117 males and 23 females) and 53 same sex siblings (84% participation), 18 yr and older, participated in the telephone questionnaire survey. The majority of interviews with GHD patients (78%) and siblings (87%) were conducted blind to the subject's clinical status. Comparisons between GHD patients and norms for standardized questionnaires indicated both better and worse functioning in several domains. In contrast, very limited differences were detected between GHD cases and same sex siblings. Isolated GHD patients were functioning better than those with multiple pituitary hormone deficiencies, but the effect sizes of these differences in most areas were relatively small. Adult height and degree of growth over the course of GH therapy were generally unrelated to QOL outcomes. Findings from the present study underscore the importance of selecting unbiased control/comparison groups in evaluating psychological outcomes among GHD adults. 相似文献
104.
The coefficient of variation is commonly used in medical and biological sciences. In this paper, several parametric and non-parametric tests for the equality of coefficients of variation in kappa populations are reviewed. Simulation studies are conducted to compare the sizes and power of these tests. It is found that the parametric tests perform well if the data are normally distributed, but perform poorly if otherwise. The non-parametric test, however, is rather robust against the underlying distribution. An example using data of the Quality Assurance Program from the Hong Kong Medical Technology Association in Haematology and Serology is provided. The insensitivity of the non-parametric test to outliers is demonstrated. 相似文献
105.
The effects of midazolam (MID) on the in vitro growth and differentiation of two murine myeloid leukemia WEHI 3B (JCS) and M1 cells were studied. MID inhibits the proliferation of both M1 and JCS cells in a dose-dependent manner. At the concentration of 10 micrograms/ml, MID was found to induce both monocytic and granulocytic differentiation of the JCS but not M1 cells. Induction of morphological differentiation of the JCS cells was also associated with the enhanced expression of the differentiation antigens Mac-1, F4/80, and Gr-1 for the cells. Results from mRNA phenotyping experiments also indicated that the expression of tumor necrosis factor (TNF-alpha) and neutrophil-specific J11d differentiation marker was significantly upregulated in MID-treated JCS cells. In addition, the phagocytic activity of MID-treated JCS cells was increased towards opsonized yeast cells. Results from this investigation suggested that MID may be used as an inducer for further study on the mechanisms of differentiation in these myeloid leukemia cells. 相似文献
106.
T Gayowski N Singh IR Marino H Vargas M Wagener C Wannstedt F Morelli T Laskus JJ Fung J Rakela TE Starzl 《Canadian Metallurgical Quarterly》1997,64(3):422-426
BACKGROUND: End-stage liver disease due to hepatitis C virus (HCV) is the most common indication for liver transplantation in U.S. veterans. We investigated the influence of HCV genotypes on the incidence and timing of recurrent HCV hepatitis, survival, infectious morbidity, and response to interferon-alpha therapy in this unique patient population. METHODS: HCV genotype was determined by direct sequencing of the NS5 region of HCV with type-specific primers. RESULTS: Genotype 1a (66%, 32/47) was the predominant genotype. Type 1b was found in 25% (12/47) of patients and type 2b was found in 9% (4/47). Histopathologically recurrent HCV hepatitis developed in 53% (25/47) of the patients after transplantation. This group included 45% (14/31) of the patients with type 1a, 67% (8/12) of the patients with type 1b, and 25% (1/4) of the patients with type 2b (P>0.5). The time to recurrence and the severity of HCV recurrence as defined by aminotransferase levels or Knodell scores were not different among the three genotypes. There was a trend toward a higher incidence of major infections in patients with type 1b (75%) versus type 1a (48%) and type 2b (50%) (P=0.11). The response to interferon-a therapy did not differ significantly among the genotypes. Mortality at 5 years was 16% (5/31) in patients with genotype 1a, 42% (5/12) in patients with genotype 1b, and 50% (2/4) in patients with genotype 2b (P=0.06). CONCLUSIONS: The incidence, time to recurrence, and response to interferon-alpha therapy did not differ between the various genotypes in our liver transplant recipients. However, there was a trend toward higher infectious morbidity and overall mortality in patients with genotype 1b after transplantation. 相似文献
107.
Chen T.P. Stella Li Fung S. Beling C.D. Lo K.F. 《Electron Devices, IEEE Transactions on》1998,45(9):1972-1977
Interface trap generation in nMOS transistors during both stressing and post-stress periods under the conditions of oxide field (dynamic and dc) stress with FN injection is investigated with charge pumping technique. In contrast to the post-stress interface trap generation induced by hot carrier stress which is a logarithmical function of post-stress time, the post-stress interface trap generation induced by oxide-field stress with FN injection first increases with post-stress time but then becomes saturated. The mechanisms for the interface trap generation in both stressing and post-stress periods are described 相似文献
108.
Technical-term translation represents one of the most difficult tasks for human translators since (1) most translators are not familiar with terms and domain-specific terminology and (2) such terms are not adequately covered by printed dictionaries. This paper describes an algorithm for translating technical words and terms from noisy parallel corpora across language groups. Given any word which is part of a technical term in the source language, the algorithm produces a ranked candidate match for it in the target language. Potential translations for the term are compiled from the matched words and are also ranked. We show how this ranked list helps translators in technical-term translation. Most algorithms for lexical and term translation focus on Indo-European language pairs, and most use a sentence-aligned clean parallel corpus without insertion, deletion or OCR noise. Our algorithm is language- and character-set-independent, and is robust to noise in the corpus. We show how our algorithm requires minimum preprocessing and is able to obtain technical-word translations without sentence-boundary identification or sentence alignment, from the English–Japanese awk manual corpus with noise arising from text insertions or deletions and on the English–Chinese HKUST bilingual corpus. We obtain a precision of 55.35% from the awk corpus for word translation including rare words, counting only the best candidate and direct translations. Translation precision of the best-candidate translation is 89.93% from the HKUST corpus. Potential term translations produced by the program help bilingual speakers to get a 47% improvement in translating technical terms. 相似文献
109.
We investigate the specific heat properties of a high-T c superconductor model, the “two-carrier model” which includes an electron-phonon interaction driven by lattice defects such as oxygen deficiencies in the otherwise conventional BCS superconductor. The normal state is identified as a two-carrier model system which is composed of two groups of charge carriers: the normal and the renormalized Bloch carriers. An enhanced normal-state electronic specific heat is obtained, and there is good agreement between theoretical predictions about the specific heat anomalies at and aboveT c and experimental data. 相似文献
110.
Chung Ming Yuen Kim Fung Tsang 《Microwave and Wireless Components Letters, IEEE》2004,14(11):525-527
This letter presents the design and implementation of a 1.8-V 5.8-GHz distributed voltage-controlled oscillator module based on bipolar transistors. The oscillator delivered -2-dBm-output power with a current consumption of 11.5 mA. The tuning range achieved was 650 MHz. The measured phase noise was -100 dBc/Hz at 1-MHz offset. The circuit construction was simple and robust and no buffer amplifier was needed. The design can be used for 5.8-GHz ISM band wireless LAN applications. 相似文献