全文获取类型
收费全文 | 915篇 |
免费 | 22篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 29篇 |
综合类 | 1篇 |
化学工业 | 95篇 |
金属工艺 | 25篇 |
机械仪表 | 16篇 |
建筑科学 | 17篇 |
矿业工程 | 4篇 |
能源动力 | 15篇 |
轻工业 | 40篇 |
水利工程 | 4篇 |
石油天然气 | 2篇 |
无线电 | 115篇 |
一般工业技术 | 56篇 |
冶金工业 | 397篇 |
原子能技术 | 10篇 |
自动化技术 | 117篇 |
出版年
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 3篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 11篇 |
2016年 | 11篇 |
2015年 | 9篇 |
2014年 | 13篇 |
2013年 | 27篇 |
2012年 | 12篇 |
2011年 | 14篇 |
2010年 | 23篇 |
2009年 | 20篇 |
2008年 | 18篇 |
2007年 | 11篇 |
2006年 | 21篇 |
2005年 | 18篇 |
2004年 | 29篇 |
2003年 | 31篇 |
2002年 | 17篇 |
2001年 | 17篇 |
2000年 | 16篇 |
1999年 | 13篇 |
1998年 | 88篇 |
1997年 | 64篇 |
1996年 | 49篇 |
1995年 | 38篇 |
1994年 | 26篇 |
1993年 | 35篇 |
1992年 | 28篇 |
1991年 | 26篇 |
1990年 | 21篇 |
1989年 | 14篇 |
1988年 | 18篇 |
1987年 | 10篇 |
1986年 | 7篇 |
1985年 | 9篇 |
1984年 | 6篇 |
1983年 | 9篇 |
1982年 | 5篇 |
1981年 | 8篇 |
1980年 | 9篇 |
1979年 | 11篇 |
1978年 | 6篇 |
1977年 | 34篇 |
1976年 | 53篇 |
1975年 | 3篇 |
1969年 | 4篇 |
1965年 | 2篇 |
排序方式: 共有943条查询结果,搜索用时 78 毫秒
91.
Overall ninety patients with chronic obstructive bronchitis presenting with signs of varying degree cardiopulmonary insufficiency (CPI) were evaluated by radionuclide ventriculography with technetium pertechnetate as well as by rotational viscosimetry of blood. The degree of hemorheological derangements tended to get higher with CPI severity (light, moderately severe, severe) being accompanied by progressing impairement of systolic and diastolic functions of both ventricles of the heart. Mechanisms of compensation of endocardiac hemodynamics were realized as a result of increase in end-diastolic and end-systolic volumes of both ventricles together with changes in amplitude and time characteristics of processes of ventricular ejection and filling. Forecast of the probable course of the condition may rely upon the functional state of right as well as left ventricle of the heart. 相似文献
92.
93.
94.
WA Franklin AF Gazdar J Haney II Wistuba FG La Rosa T Kennedy DM Ritchey YE Miller 《Canadian Metallurgical Quarterly》1997,100(8):2133-2137
Individuals with one aerodigestive tract malignancy have a high incidence of second primary aerodigestive tumors. The mechanism for this field effect has not been determined. We studied an individual with widespread dysplastic changes in the respiratory epithelium but no overt carcinoma. The entire tracheobronchial tree obtained at autopsy was embedded in paraffin, and bronchial epithelial cells were isolated by microdissection. DNA extracted from the microdissected cells was analyzed for point mutations in the p53 tumor suppressor gene. A single, identical point mutation consisting of a G:C to T:A transversion in codon 245 was identified in bronchial epithelium from 7 of 10 sites in both lungs. Epithelium at sites containing the p53 mutation was morphologically abnormal, exhibiting squamous metaplasia and mild to moderate atypia. No invasive tumor was found in the tracheobronchial tree or any other location. Cells from peripheral blood, kidney, liver, and lymph node exhibited no abnormality in the p53 gene. The widespread presence of a single somatic p53 point mutation in the bronchi of a smoker suggests that a single progenitor bronchial epithelial clone may expand to populate broad areas of the bronchial mucosa-a novel mechanism for field carcinogenesis in the respiratory epithelium that may be of importance in assessing individuals for risk of a second primary tumor as well as in devising effective strategies for chemoprevention of lung cancer. 相似文献
95.
This study was undertaken to establish a new technology, using pre-treatment with electrolyzed NaCl solutions and essential oil compounds, to extend the shelf-life of carp fillets. Samples of skinless carp fillets were treated with 100-fold (by weight) of electrolyzed NaCl solutions [cathodic solution, EW(−) and/or anodic solution, EW(+)] and 1% oil (0.5% carvacrol + 0.5% thymol) [1%(C + T)]. Then chemical [pH, volatile basic nitrogen, peroxide value, and thiobarbituric acid], microbiological (total viable count) and sensory analyses were used to evaluate the preservative effect of this new technology during storage at 5 and 25 °C. Our results from the chemical assays indicated that EW(−), followed by EW(+) and subsequently 1%(C + T) [EW(−)/EW(+)/1%(C + T)], significantly suppressed the lipid oxidation compared with other treatments. Data from sensory evaluation and microbiological assay showed that treatment with EW(−)/EW(+)/1%(C + T) extended the shelf-life of carp fillets to 16 and 1.3 days compared with 4 and 0.3 days for the control samples during storage at 5 and 25 °C, respectively. 相似文献
96.
Fogle A. Darling D. Blish R.C. II Daszko G. 《Device and Materials Reliability, IEEE Transactions on》2005,5(2):297
The authors thank G. Cellere and A. Paccagnella for their comments (see ibid., vol.5, no.2, p.296-7, June 2005) and for taking the time to thoroughly review their paper (see ibid., vol.4, no.3, p.371-6, Sep. 2004). The original intent of the experiment and paper was to measure and report the overall susceptibility of flash memory to upsets caused by neutron and proton irradiation. They did not care to speculate on root cause(s) because the failure rate was small relative to other elements of an electronic system (SRAM, random logic, etc). 相似文献
97.
Jonathan H. Christian Kevin M. Fox Aaron L. Washington II 《International Journal of Applied Glass Science》2017,8(2):158-164
The microwave heating of a crystal-free and a partially trevorite-crystallized nuclear waste glass simulant was evaluated. Our results show that a 500-mg monolith of partially crystallized waste glass can be heated from room temperature to above 1600°C within 2 minutes using a single-mode, highly focused, 2.45-GHz microwave, operating at 300 W. Using X-ray diffraction measurements, we show that trevorite is no longer detectable after irradiation and thermal quenching. When a crystal-free analog of the same waste glass simulant composition was exposed to the same microwave radiation, it could not be heated above 450°C regardless of the heating time. The reduction in crystalline content achieved by selectively heating spinels in the presence of glass suggests that microwave-specific heating should be further explored as a technique for remediating crystal accumulation in a glass melt. 相似文献
98.
Felipe Guerrero-Barba II Miguel A. Cabrerizo-Vílchez Miguel A. Rodríguez-Valverde 《Journal of Materials Science》2014,49(22):7723-7729
In hot asphalt applications, the adhesion between bitumen and mineral aggregate is usually described in terms of bitumen surface tension and contact angle of the bitumen over the aggregate. However, the quantification of the physico-chemical bond between bitumen and aggregate under realistic conditions is a nontrivial task. In this work, we designed a high-temperature goniometer to measure the contact angle of liquid bitumen on mineral aggregate substrates. The drop deposition was conducted once the thermal equilibrium between liquid bitumen and aggregate was attained. We monitored the spreading of sessile drops of viscous naphthenic bitumen and asphaltic bitumen on polished sheets of calcareous aggregates at high temperature (70–100 °C). A near complete wetting with very low contact angles (13– \(24^{\circ }\) ) was reproduced regardless of the bitumen origin and temperature. Furthermore, the coating degree of the naphthenic and asphaltic bitumens on the calcareous aggregates at high temperature was apparently similar. We found that the bitumen-aggregate adhesion is adequately described by dynamic spreading rather than by equilibrium wettability. Spreading kinetics was ruled by the particular properties of each bitumen such as viscosity and acid index. We found evidences of acid etching of the naphthenic bitumen on the calcareous aggregates during spreading at high temperature. 相似文献
99.
Zhengran He Kai Xiao William Durant Dale K. Hensley John E. Anthony Kunlun Hong S. Michael Kilbey II Jihua Chen Dawen Li 《Advanced functional materials》2011,21(19):3617-3623
In this study, inorganic silica nanoparticles are used to manipulate the morphology of 6,13‐bis(triisopropylsilylethynyl)‐pentacene (TIPS pentacene) thin films and the performance of solution‐processed organic thin‐film transistors (OTFTs). This approach is taken to control crystal anisotropy, which is the origin of poor consistency in TIPS pentacene based OTFT devices. Thin film active layers are produced by drop‐casting mixtures of SiO2 nanoparticles and TIPS pentacene. The resultant drop‐cast films yield improved morphological uniformity at ~10% SiO2 loading, which also leads to a 3‐fold increase in average mobility and nearly 4 times reduction in the ratio of measured mobility standard deviation (μStdev) to average mobility (μAvg). Grazing‐incidence X‐ray diffraction, scanning and transmission electron microscopy as well as polarized optical microscopy are used to investigate the nanoparticle‐mediated TIPS pentacene crystallization. The experimental results suggest that the SiO2 nanoparticles mostly aggregate at TIPS pentacene grain boundaries, and 10% nanoparticle concentration effectively reduces the undesirable crystal misorientation without considerably compromising TIPS pentacene crystallinity. 相似文献
100.
Hendrix D. Cross J.H. II Maghsoodloo S. 《IEEE transactions on pattern analysis and machine intelligence》2002,28(5):463-477
Recently, the first two in a series of planned comprehension experiments were performed to measure the effect of the control structure diagram (CSD) on program comprehensibility. Upper- and lower-division computer science and software engineering students were asked to respond to questions regarding the structure and execution of one source code module of a public domain graphics library. The time taken for each response and the correctness of each response was recorded. Statistical analysis of the data collected from these two experiments revealed that the CSD was highly significant in enhancing the subjects' performance in this program comprehension task. The results of these initial experiments promise to shed light on fundamental questions regarding the effect of software visualizations on program comprehensibility 相似文献