全文获取类型
收费全文 | 2799篇 |
免费 | 5篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 2篇 |
综合类 | 6篇 |
化学工业 | 17篇 |
机械仪表 | 6篇 |
建筑科学 | 3篇 |
能源动力 | 16篇 |
轻工业 | 30篇 |
水利工程 | 2篇 |
无线电 | 16篇 |
一般工业技术 | 39篇 |
冶金工业 | 2657篇 |
原子能技术 | 2篇 |
自动化技术 | 9篇 |
出版年
2024年 | 1篇 |
2023年 | 7篇 |
2022年 | 4篇 |
2021年 | 11篇 |
2020年 | 8篇 |
2019年 | 8篇 |
2018年 | 9篇 |
2017年 | 5篇 |
2016年 | 4篇 |
2015年 | 2篇 |
2014年 | 7篇 |
2013年 | 11篇 |
2012年 | 2篇 |
2011年 | 5篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 4篇 |
2007年 | 3篇 |
2006年 | 2篇 |
2005年 | 3篇 |
2004年 | 8篇 |
2003年 | 9篇 |
2002年 | 1篇 |
2000年 | 2篇 |
1999年 | 106篇 |
1998年 | 870篇 |
1997年 | 497篇 |
1996年 | 333篇 |
1995年 | 167篇 |
1994年 | 138篇 |
1993年 | 179篇 |
1992年 | 12篇 |
1991年 | 22篇 |
1990年 | 27篇 |
1989年 | 32篇 |
1988年 | 17篇 |
1987年 | 21篇 |
1986年 | 20篇 |
1985年 | 27篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 14篇 |
1981年 | 8篇 |
1980年 | 29篇 |
1979年 | 1篇 |
1978年 | 5篇 |
1977年 | 49篇 |
1976年 | 99篇 |
1975年 | 2篇 |
1973年 | 2篇 |
排序方式: 共有2805条查询结果,搜索用时 0 毫秒
991.
992.
993.
On the basis of a profound clinico-biochemical study of 182 patients with hypertensive disease the authors established that the development of chronic insufficiency of cerebral circulation in this disorder is accompanied by quantitative and physico-chemical changes in the lipoprotein metabolism. These indices do not change significantly following short sessions of heparinotherpy and comprehensive treatment. Their diagnostical significance for medico-occupational examinations is discussed. 相似文献
994.
995.
996.
Ory JJ; Mazhary A; Kuang H; Davies RR; Distefano MD; Banaszak LJ 《Protein engineering, design & selection : PEDS》1998,11(4):253-261
Adipocyte lipid-binding protein (ALBP) is a small (14.5 kDa) 10- strandedbeta-barrel protein found in mammalian fat cells. The crystal structures ofvarious holo-forms of ALBP have been solved and show the fatty acid ligandbound in a large (approximately 400 A3) cavity isolated from bulk solvent.Examination of the cavity suggests that it would be a good site for thecreation of an artificial catalyst, as numerous well defined crystalstructures of ALBP are available and past studies have shown theconformation to be reasonably tolerant to modification and mutagenesis.Previous work has shown ALBP to be a good protein scaffold for exploringenantio- and stereoselective reactions; two constructs, ALBP attached toeither a pyridoxamine or a phenanthroline group at C117, have beenchemically characterized. Both modified proteins have been crystallized andtheir structures solved and refined. The X-ray models have been used toexamine the origin of the chiral selectivity seen in the products. It isapparent that these covalent adducts reduce the internal cavity volume,sterically limiting substrate interactions with the reactive groups, aswell as solvent access to potential intermediates in the reaction pathway. 相似文献
997.
MD Shahrukh Adnan Khan Yoong Choon Chang Md Ashraful Kabir Muhammad Izuan Fahmi Bin Romli Chockalingam Aravind Vaithilingam Jakir Hosain 《电子科技学刊:英文版》2021,19(4):379-389
In this paper, extensive efforts have been undertaken to design and develop a control system, which is incorporated with an energy storage device that can store energy from low-voltage renewable sources. The developed device acts as a storage element, which can be used to charge small-scale batteries, cellular devices, and other applications in remote places where the grid connection is not available. The circuit is developed using a case-by-case analysis. In order to solve the low output voltage problem, a bipolar junction transistor-metal oxide semiconductor field-effect transistor (BJT-MOSFET) based switch control technology with the Arduino microcontroller has been implemented. The developed control system is extremely efficient in charging batteries through a supercapacitor for low-voltage sources. In this research, a small-scale 200-W portable vertical axis wind turbine is used at a wind speed of 3 m/s. The result shows the efficiency of the proposed system as compared with the conventional systems. The proposed system can be an important tool of the latest distributed energy generation technology which is an important part of a smart city. Lastly, the limitations and future scopes of the development of the control device are discussed for the future barrier. An important future scope identified is to integrate the Internet of Things based mobile interface for remote monitoring for any kind of pandemic situation like COVID-19. Now, it is high time to get our smart city concept aligned with the post COVID pandemic situation and get us prepared smartly for similar future occurrences. 相似文献
998.
A low cost box-type solar cooker made of two paper carton boxes with crumpled newspaper balls as insulation has been fabricated with a tilted aperture plane. Comparative tests of this cooker have been conducted against a normal type costlier solar cooker with 1000 ml load of water in each of the cookers. It has been observed that on a sunny day water temperature initially increases more rapidly in the new cooker compared to the normal type cooker. But at temperatures higher than 90°C both the cookers perform similarly. Two figures of merit F1 and F2 have also been found to be satisfactory. An arrangement of low cost auxiliary heating using a 100w electric bulb inside a blackened metal casing allows the carton box cooker to reach cooking temperatures under cloudy conditions with ease when the normal type solar cooker fails. The cost of materials for the new cooker is within US $10 and has been observed to be as effective as the normal type solar cooker which requires between US $40 and $65 to fabricate. 相似文献
999.
Miah MD. Ashraful Alam Md. Mahbubul Alam Shigeru Matsuo Kenbu Teramoto Toshiaki Setoguchi Heuy Dong Kim Shen Yu 《热科学学报(英文版)》2007,16(1):33-39
Numerical simulations have been carried out for a supersonic two-dimensional flow over open,rectangular cavi-ties(length-to-depth ratios are L/D=1.0 and 3.0)in order to investigate the effect of non-equilibrium condensa-tion of moist air on supersonic internal flows around the cavity for the flow Mach number 1.83 at the cavity en-trance.In the present computational investigation,a condensing flow was produced by an expansion of moist airin a Laval nozzle.The computational results showed that the upstream traveling compression waves becomeweaker than those without the condensation.Consequently,the weaker compression waves cannot excite theshear layer strongly and amplitudes of oscillation in the cavity became smaller than those without the condensa-tion.The occurrence of the non-equilibrium condensation in case of L/D=1.0 affected strongly the amplitude andfrequency of oscillation in the cavity compared with L/D=3.0. 相似文献
1000.
We report a patient with a parkinsonian syndrome induced by sertraline (Zoloft), an SSRI antidepressant, whose symptoms resolved after the drug was discontinued. This case prompted us to investigate the effect of sertraline on dopamine metabolism in animals. Sertraline (30 mg/kg, i.p.) or placebo (vehicle) was administered to two groups of six normal, anesthetized rats and using cerebral microdyalisis extracellular striatal levels of dopamine, the dopamine metabolites (HVA and DOPAC), as well as the serotonin metabolite 5-HIIA were monitored. In animals pre-treated with sertraline, DOPAC, HVA, and 5-HIAA levels were significantly decreased compared to control animals (p < 0.01). These data indicate that sertraline has an effect on dopamine metabolism, which may alter function in the striatum and induce a parkinsonian syndrome. 相似文献