全文获取类型
收费全文 | 627篇 |
免费 | 33篇 |
专业分类
电工技术 | 7篇 |
综合类 | 1篇 |
化学工业 | 169篇 |
金属工艺 | 14篇 |
机械仪表 | 16篇 |
建筑科学 | 17篇 |
能源动力 | 41篇 |
轻工业 | 84篇 |
水利工程 | 3篇 |
石油天然气 | 3篇 |
无线电 | 46篇 |
一般工业技术 | 90篇 |
冶金工业 | 56篇 |
原子能技术 | 8篇 |
自动化技术 | 105篇 |
出版年
2024年 | 2篇 |
2023年 | 8篇 |
2022年 | 10篇 |
2021年 | 39篇 |
2020年 | 15篇 |
2019年 | 26篇 |
2018年 | 22篇 |
2017年 | 27篇 |
2016年 | 26篇 |
2015年 | 16篇 |
2014年 | 26篇 |
2013年 | 30篇 |
2012年 | 38篇 |
2011年 | 45篇 |
2010年 | 30篇 |
2009年 | 38篇 |
2008年 | 31篇 |
2007年 | 20篇 |
2006年 | 18篇 |
2005年 | 19篇 |
2004年 | 19篇 |
2003年 | 13篇 |
2002年 | 20篇 |
2001年 | 12篇 |
2000年 | 7篇 |
1999年 | 5篇 |
1998年 | 12篇 |
1997年 | 11篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 6篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1973年 | 2篇 |
1971年 | 2篇 |
1962年 | 1篇 |
1949年 | 1篇 |
排序方式: 共有660条查询结果,搜索用时 15 毫秒
91.
In this work we make a first, partial, assessment of the low- to medium-temperature geothermal reserves of Mexico. The assessment covers about 30% of the identified geothermal surface manifestations. For reserve assessment we use the volume method, supplemented by Montecarlo simulations and statistics, in order to quantify the inherent uncertainties. We estimate these reserves as lying between 7.7 × 1016 and 8.6 × 1016 kJ, with 90% confidence. The distribution of most likely reservoir temperatures is in the 60–180 °C range, with a mean of 111 °C. These massive amounts of recoverable energy and the associated temperatures are potentially important for the economic development of the associated geothermal localities. 相似文献
92.
JL Goldberg CL Zanella YM Janssen CR Timblin LA Jimenez P Vacek DJ Taatjes BT Mossman 《Canadian Metallurgical Quarterly》1997,17(3):265-271
We developed in situ dual-fluorescence detection techniques for measuring apoptosis and proliferation simultaneously in single dishes of cells. The deoxyribonucleic acid (DNA)-specific labeling method, terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate nick-end labeling (TUNEL), first was used in conjunction with a 4',6-diamidino-2-phenylindole (DAPI) counterstain to detect and measure morphologic characteristics of apoptotic rat pleural mesothelial (RPM) cells isolated from Fischer 344 rats and exposed to 300 microM hydrogen peroxide (H2O2). For this purpose, 100 TUNEL-positive nuclei were measured while being viewed with DAPI counterstaining for area, perimeter, longest diameter, and average diameter, using imaging software and an image-collection apparatus. We then exposed cells to a range of concentrations of crocidolite asbestos and putative apoptotic and mitogenic agents. Exposure to crocidolite asbestos (5 microg/cm2) caused a striking dose-dependent apoptotic response at 24 h, 48 h, and 72 h. The nonfibrous crocidolite analogue riebeckite failed to induce apoptosis. At 24 h, tumor necrosis factor-alpha (TNF-alpha) (10 ng/ml) caused an increase in apoptotic nuclei. A second method, utilizing an antibody to 5'-bromodeoxyridine (BrdU) and oxazole yellow homodimer (YOYO), showed a dose-dependent increase in proliferation occurring in cells exposed to asbestos (5 microg/cm2) at 48 h and 72 h. In addition, increased numbers of rat pleural mesothelial (RPM) cells exposed to 12-O-tetradecanoylphorbol-13-acetate (TPA), TNF-alpha, and epidermal growth factor (EGF) exhibited incorporation of BrdU at these time points, although total numbers of cells per unit area were unchanged. Results indicate a dynamic balance between apoptosis and increased DNA synthesis after exposure of mesothelial cells to asbestos. 相似文献
93.
Michael Basin Joel Perez Rodolfo Martinez‐Zuniga 《International Journal of Adaptive Control and Signal Processing》2006,20(10):509-517
In this paper, the optimal filtering problem for linear systems with state delay over linear observations is treated using the optimal estimate of the state transition matrix. As a result, the alternative optimal filter is derived in the form similar to the traditional Kalman–Bucy one, i.e. consists of only two equations, for the optimal estimate and the estimation error variance. This presents a significant advantage in comparison to the previously obtained optimal filter (IEEE Trans. Autom. Control 2005; 50 :684–690), which includes a variable number of covariance equations, unboundedly growing as the filtering horizon tends to infinity. Performances of the two optimal filters are compared in example; the obtained results are discussed. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
94.
No abstract. Copyright 1998 The Association for the Study of Animal Behaviour. 相似文献
95.
Suspension and centrifugation of crude microsomes of rat liver in low ionic strength solution separated a soluble protein
fraction that is necessary for the full activity of the linoleic acid desaturase. The fraction partially purified through
Sephadex G-150 still retains lipids which are mainly constituted by phosphatidylcholine. Linoleic acid predominates in the
fatty acid composition. By NaCl gradient centrifugation and electrophoresis in gelatinized cellulose acetate, the factor behaves
like a lipoprotein. The factor binds linoleic acid and linolyl-CoA that are desaturated to γ-linolenic acid when incubated
with washed microsomes. Albumin does not replace the factor. 相似文献
96.
Effect of the environment and fasting on the lipid and fatty acid composition ofDiplodom patagonicus
Some effects of food, habitat and temperature on the lipid composition of a freshwater mollusk,Diplodom patagonicus, were studied. Animals kept and fasted up to 60 days in an aquarium at 9 C and 20 C showed a decrease of the total lipid
content that corresponded to a decrease of triacylglycerols and diacylglycerol ethers. This decrease evoked an increase of
polar-to-nonpolar lipid ratio. However, no significant change in the total fatty acid composition was shown. Moreover, a decrease
of temperature from 20 C to 9 C decreased the incorporation of labeled linoleic and α-linolenic acid into the lipids, but
did not modify the unsaturated: saturated acid ratio of the mollusk lipids during this period. A change of habitat from lake
to estuary changed very significantly the fatty acid composition of the animal. The ω6 acids, linoleic and arachidonic, typical
ofD. patagonicus living in the lake, were partially replaced by ω3 acids. That this change was due to a change of food composition was indicated
by the fatty acids of corresponding sediments. Therefore, the fatty acid composition ofD. patagonicus is highly sensitive to food composition and varies little with temperature and seasonal changes.
Member of Carrera del Investigador Científico de la Comisión de Investigaciones Científicas de la Provincia de Buenos Aires.
Member of Carrera del Investigador Científico del Consejo Nacional de Investigaciones Ciéntíficas y Técnicas, Argentina. 相似文献
97.
Gustavo Cabib Humberto J. Silva Ana Giulietti Rodolfo Ertola 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1983,33(1):21-28
Stillage from cane molasses alcohol for SCP production was used for the growth of strains of Candida and Paecilomyces as SCP sources. The results of small and large scale experiments carried out with a Candida utilis strain with data on chemical composition, amino acid profile, vitamin content and biological value of the cell material are given. 相似文献
98.
99.
The desaturation of stearic, linoleic, and α-linolenic acids by human liver microsomes were studied. The microsomes were isolated from liver biopsies obtained during operations. It was shown that human liver microsomes are able to desaturate 1-14C-α-linolenic acid to octadeca-6,9,12,15-tetraenoic acid; 1-14C-linoleic acid to γ-linolenic acid; and 1-14C-stearic acid to oleic acid in the same system described in the rat. However, the desaturation activity obtained was low compared to other mammals. This effect was attributed to fasting, premedication, or the anaesthesia. 相似文献
100.