全文获取类型
收费全文 | 56325篇 |
免费 | 5783篇 |
国内免费 | 2804篇 |
专业分类
电工技术 | 1942篇 |
综合类 | 4219篇 |
化学工业 | 18800篇 |
金属工艺 | 5011篇 |
机械仪表 | 2023篇 |
建筑科学 | 6527篇 |
矿业工程 | 964篇 |
能源动力 | 3399篇 |
轻工业 | 3444篇 |
水利工程 | 583篇 |
石油天然气 | 1341篇 |
武器工业 | 637篇 |
无线电 | 1529篇 |
一般工业技术 | 11583篇 |
冶金工业 | 1594篇 |
原子能技术 | 210篇 |
自动化技术 | 1106篇 |
出版年
2024年 | 298篇 |
2023年 | 915篇 |
2022年 | 1693篇 |
2021年 | 2068篇 |
2020年 | 2059篇 |
2019年 | 1763篇 |
2018年 | 1551篇 |
2017年 | 2051篇 |
2016年 | 2038篇 |
2015年 | 1970篇 |
2014年 | 2940篇 |
2013年 | 2957篇 |
2012年 | 4091篇 |
2011年 | 4112篇 |
2010年 | 3317篇 |
2009年 | 3397篇 |
2008年 | 2746篇 |
2007年 | 3792篇 |
2006年 | 3422篇 |
2005年 | 2918篇 |
2004年 | 2393篇 |
2003年 | 2178篇 |
2002年 | 1741篇 |
2001年 | 1556篇 |
2000年 | 1370篇 |
1999年 | 1139篇 |
1998年 | 917篇 |
1997年 | 762篇 |
1996年 | 624篇 |
1995年 | 483篇 |
1994年 | 433篇 |
1993年 | 377篇 |
1992年 | 249篇 |
1991年 | 190篇 |
1990年 | 108篇 |
1989年 | 62篇 |
1988年 | 60篇 |
1987年 | 38篇 |
1986年 | 17篇 |
1985年 | 20篇 |
1984年 | 17篇 |
1983年 | 8篇 |
1982年 | 14篇 |
1980年 | 19篇 |
1979年 | 8篇 |
1977年 | 2篇 |
1967年 | 1篇 |
1957年 | 1篇 |
1956年 | 1篇 |
1951年 | 24篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
141.
Sang Cheol Lee Won Kook Lee 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1992,55(3):251-261
The extraction of penicillin G from simulated media was performed by water/oil/water (w/o/w) emulsion liquid membranes (ELMs) and studied under various operational conditions in a batch system. The degree of extraction achieved was between 80% and 95% under specific conditions. A concentration of greater than nine times the initial concentration of penicillin G in the external phase was obtained in the internal phase. The pH of the internal aqueous solution, containing a basic salt, was theoretically calculated on the basis of the amount of penicillin G transported into the internal phase. The calculated results agreed with the experimental data well and were used to select a suitable type and concentration of a basic salt in the internal phase to give a pH within the range 5 to 8 where penicillin G was stable after the termination of extraction. The extraction of penicillin G was successfully performed by the ELM process with sodium carbonate in the internal phase. 相似文献
142.
应用复合纺丝方法并通过加弹、空气变形等措施使NPCDP/PET异染异收缩纤维获得优良的毛性感。简要介绍了复合纺丝的工艺路线,讨论了纺丝温度、压力、干燥工艺、拉伸条件对可纺性的影响,并明确了变形工艺对复合纤维的影响作用。制得的NPCDP/PET复合纤维物理力学性能符合后加工要求,织物的缓弹回复角达305度。 相似文献
143.
On the mechanical behavior of aluminum alloys reinforced by long or short alumina fibers or SiC whiskers 总被引:2,自引:0,他引:2
This study was initiated to examine the dispersion of longitudinal and transverse waves in metal matrix composites in order to obtain the dynamic elastic modulus and to evaluate various models for predicting the composite's macroscopic elastic constants from the properties of its constituents. The materials chosen for this investigation were alumina continuous fibers on the one hand and alumina and SiC short fibers on the other hand, all embedded in an aluminum alloy matrix. In addition, some indications have been obtained experimentally for the acoustoelastic effect in the composite. 相似文献
144.
本文描述了醋酸纤维素-纤维素大孔增强超滤膜的结构特征一分离性能之间的关系。详细论述了膜材料含量和粘连剂含量及其分子量对膜结构和性能的影响。论述了不同配方铸膜液的膜,其孔径,水通量和截留率随操作压力的变化规律。实验证明这种高强度的CAC膜经多次重复使用后,其结构性能保持完好。 相似文献
145.
Naoki Takinami Takashi Chino Shotaro Yoshida Isao Miura Kazuo Watanabe Kazuo Amano 《Electrical Engineering in Japan》1994,114(6):1-12
When ground-fault problems occur on a cable line, immediate fault location and restoration are required. Therefore, various new methods to locate the fault point instantaneously have been investigated to replace such conventional methods as the Murray loop method and the pulse radar method [1]. These methods require a long time to locate the fault point. One possible fault location method is to sense the temperature rise following a ground fault using a fiber optic distributed temperature sensor. Application of this method was found feasible through sensing the temperature rise at a ground-fault test using a thermocouple as a temperature sensor with test cables [4]. A power/optical composite cable was prepared experimentally and after verifying its thermal mechanical performance, the temperature rise at an incidence of a fault was determined and the anticipated performance was demonstrated in a ground-fault test. This article describes the outline of the test. 相似文献
146.
研究了水对植物纤维水泥复合板性能的影响。选择合适的水分可以提高板材静弯曲强度,减小板材变形。 相似文献
147.
聚乙烯醇膜的阻醇及导电性能(Ⅱ)戊二醛交联聚乙烯醇膜 总被引:3,自引:0,他引:3
为提高直接甲醇燃料电池(DMFC)用膜的阻醇性能,采用在渗透蒸发领域广泛使用且具有良好分离效果的聚乙烯醇(PVA)为主要材料,制备了戊二醛(GA)交联PVA膜,考察了此类膜的阻醇及质子导电能力。PVA(GA)膜的阻醇效果较目前在DMFC中广泛使用的Nation膜有显著提高,但其自身不具有质子导电能力,需外加电解质溶液以提高其电导率。 相似文献
148.
Intercalation of poly[oligo(oxyethylene) methacrylates] onto sodium montmorillonite (MMT) clay has been investigated. A polymer–clay hybrid has been synthesized through intercalation of the monomer followed by its solution free‐radical polymerization. Eight polymer–clay hybrids were prepared using different weight ratios of clay, different oligo(oxyethylene) lengths and different proportions of crosslinker. Evidence of the development of nanostructures is obtained from scanning electron microscopy, and wide‐angle X‐ray diffraction studies support these results which show disappearance of the peak characteristic to d001 spacing. In this hybrid MMT is dispersed homogeneously in the polymer matrix. © 2003 Society of Chemical Industry 相似文献
149.
采用多模复合导引头提高反舰导弹突防能力 总被引:4,自引:0,他引:4
分析了现有反舰导弹制导体制的特点,提出了反舰导弹如采用被动微波/红外成像双模复合导引头,将是提高其突防能力的有力举措,同时提出了研制主被动/红外成像三模复合导引头的建议,并给出了三模导引头结构布局示意图。 相似文献
150.
Ibuprofen is a well-known nonsteroidal anti-inflammatory drug, which can interact with lipid membranes. In this paper, the interaction of ibuprofen with bilayer lipid membrane was studied by UV-vis spectroscopy, cyclic voltammetry and AC impedance spectroscopy. UV-vis spectroscopy data indicated directly that ibuprofen could interact with lipid vesicles. In electrochemical experiments, ibuprofen displayed a biphasic behavior on bilayer lipid membrane supported on a glassy carbon electrode. It could stabilize the lipid membrane in low concentration, while it induced defects formation, even removed off bilayer lipid membrane from the surface of the electrode with increasing concentration. The mechanism about the interaction between ibuprofen and supported bilayer lipid membrane was discussed. 相似文献