全文获取类型
收费全文 | 43306篇 |
免费 | 5619篇 |
国内免费 | 3498篇 |
专业分类
电工技术 | 4732篇 |
综合类 | 4667篇 |
化学工业 | 4070篇 |
金属工艺 | 1141篇 |
机械仪表 | 2376篇 |
建筑科学 | 2745篇 |
矿业工程 | 993篇 |
能源动力 | 1171篇 |
轻工业 | 2222篇 |
水利工程 | 946篇 |
石油天然气 | 1716篇 |
武器工业 | 697篇 |
无线电 | 6234篇 |
一般工业技术 | 4176篇 |
冶金工业 | 1751篇 |
原子能技术 | 665篇 |
自动化技术 | 12121篇 |
出版年
2024年 | 202篇 |
2023年 | 571篇 |
2022年 | 1063篇 |
2021年 | 1254篇 |
2020年 | 1541篇 |
2019年 | 1465篇 |
2018年 | 1298篇 |
2017年 | 1704篇 |
2016年 | 1908篇 |
2015年 | 1989篇 |
2014年 | 2696篇 |
2013年 | 3136篇 |
2012年 | 3092篇 |
2011年 | 3225篇 |
2010年 | 2396篇 |
2009年 | 2537篇 |
2008年 | 2508篇 |
2007年 | 2967篇 |
2006年 | 2706篇 |
2005年 | 2234篇 |
2004年 | 1796篇 |
2003年 | 1689篇 |
2002年 | 1447篇 |
2001年 | 1275篇 |
2000年 | 1070篇 |
1999年 | 812篇 |
1998年 | 647篇 |
1997年 | 579篇 |
1996年 | 439篇 |
1995年 | 387篇 |
1994年 | 320篇 |
1993年 | 256篇 |
1992年 | 186篇 |
1991年 | 180篇 |
1990年 | 130篇 |
1989年 | 104篇 |
1988年 | 74篇 |
1987年 | 71篇 |
1986年 | 55篇 |
1985年 | 60篇 |
1984年 | 49篇 |
1983年 | 34篇 |
1982年 | 33篇 |
1981年 | 29篇 |
1980年 | 24篇 |
1979年 | 23篇 |
1978年 | 16篇 |
1977年 | 13篇 |
1959年 | 12篇 |
1956年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
101.
ABSTRACT: The effect of post-cooking holding-time on sensory assessment of low (89 g/kg) and high (218 g/kg) fat beefburgers was assessed. Burgers were served to panelists approximately 3 or 18 min after cooking. Fat content influenced fattiness, moistness/juiciness and overall appearance (P < 0.05), overall acceptability and overall texture (P< 0.01) and tenderness and crumbliness (p<0.001). Burgers with the higher fat content had higher scores. Holding-time influenced sensory overall appearance only with lower scores at extended holding times (P < 0.01). Treatment differences were small, mostly less than one sensory scale unit. Higher lightness and yellowness values were found for burgers with higher fat contents. 相似文献
102.
103.
液位定量式灌装机的灌装精度概率模型与可靠度计算模型 总被引:1,自引:0,他引:1
描述了控制液位定量式灌装机的灌装时间与灌装精度的关系,推导出实际灌装时间的理论计算公式。针对实际存在的各种随机变量对灌装时间的影响,建立了灌装时间的概率模型,提出基于灌装时间随机误差的灌状精度以及灌装精度可靠度概念,并相应建立出灌装精度概率模型与灌装精度可靠度计算模型。 相似文献
104.
The paper deals with I/O versions of receding horizon controllers based on the minimization of multistep quadratic costs with the constraint that the terminal state goes to zero. The resulting control law yields stable closed-loop systems under sharp conditions. Simulation results are presented to both verify the theoretical analysis and relate the new control law with GPC 相似文献
105.
The design of feedback-linearization and poles-placement controllers for discrete-time non-linear plants, using Input/Output/State measurements only, is typically addressed via indirect design. In this paper we propose the use of a new technique, based on a Virtual Input Direct Design (VID2) approach. The main feature of such a technique is to reduce the control design problem into a standard non-linear mapping approximation problem, without calling for the preliminary construction of an appropriate model of the plant. As compared with the existing methods, the new one requires less computational effort, while taking full advantage of the non-linear approximation software tools already available. In this paper, the new method is described, a simple theoretical analysis is given, and some numerical examples are presented. 相似文献
106.
A. BETTERO M. R. ANGI F. GALIANO C. A. BENASSI 《International journal of cosmetic science》1985,7(1):1-8
To assess ocular irritancy caused by chemical and cosmetic products a reliable method based on evaluation of histamine (Hm) in tears is presented. Hm is measured at picomole levels by HPLC and fluorimetric detection after fluorescamine-HM derivatization. In order to avoid any uncontrolled irritation and stimulation of the conjunctiva during sample collection, a procedure of conjunctiva lavage was developed. A balanced salt solution (50 μl) containing a known amount of Hm-fluorophore as reference standard is instilled in the conjunctiva fornix. After a few seconds 20 μl of tear fluid is collected: 10 μl are immediately analysed and 10 μl after derivatization reaction. In this way it is possible to evaluate tear dilution and to assess Hm content in less than 10 minutes.
In a group of 20 normal subjects Hm has been determined in comparison with that of two volunteers after topical application of 50 μ of 0.2% and 0.4% sodium lauryl sulphate solution. A contact of 30 seconds of the cosmetic ingredient caused an immediate dose-dependent Hm release through a direct cytotoxic damage of cell membranes due to the surfactant action.
Évaluation de l'irritation occulaire due aux cosmétiques par la détermination de l'histamine lacrimale 相似文献
In a group of 20 normal subjects Hm has been determined in comparison with that of two volunteers after topical application of 50 μ of 0.2% and 0.4% sodium lauryl sulphate solution. A contact of 30 seconds of the cosmetic ingredient caused an immediate dose-dependent Hm release through a direct cytotoxic damage of cell membranes due to the surfactant action.
Évaluation de l'irritation occulaire due aux cosmétiques par la détermination de l'histamine lacrimale 相似文献
107.
低渗透油藏生产井关井测压时间的计算与应用 总被引:4,自引:4,他引:0
低渗透油藏的生产井压裂后,在单井试油试采过程中,压力恢复测试关井时间不同,其中有些井压力恢复曲线不能出现边界反应段,渗流不能反映地层中真实流动特征。针对这种情况,基于长庆绥靖油田塞39井区长:低渗透油藏大量试井和实际生产资料,利用现代试井解释理论,研究合理关井时间的界限及其计算方法。结果表明,当油井关井测压时间达到3倍地层径向流开始出现的时间后,利用此时的压力数据解释地层参数和地层压力,其结果的误差小于5%,同时能较准确地判断边界类型。计算的理论曲线和霍纳法解释值非常接近,对于塞39井区,若预先知道某生产井地层有效渗透率值,可从理论曲线查出压力恢复试井的关井时间,否则,建议按照该井区地层有效渗透率(大约在6mD左右),将不稳定试井测试时间控制在25d以上为宜。图4表3参14 相似文献
108.
Process Variables, Gelatinized Starch and Moisture Effects on Physical Properties of Mungbean Noodles 总被引:2,自引:0,他引:2
The effects of amounts of gelatinized starch and moisture in the final slurry or dough, cooking time, holding time, and holding temperature on physical properties of mungbean noodles were studied. Cooking loss, cutting stress, work to cut, and transparency of noodles were measured. Moisture content of the final slurry or dough, cooking time, and holding temperature were the most important factors that affected physical properties of mungbean noodles. Processing should be done at moisture contents not exceeding 55%, cooking times not longer than 40 set, and holding temperatures not lower than 3° using 5% of total starch as gelatinized starch and holding time of 36 hr. 相似文献
109.
本文重点介绍了方波依赖在音频测量,设备的维护检测及录音均衡自动调节等音频技术中的应用,并通过对方波信号的频谱特性和方波信号通过线性系统的频域特性的分析,简要说明了方波信号在应用电路中的基本工作原理。 相似文献
110.
以Takens嵌入定理和影子定理为理论依据,提出一种能对混沌信号去噪的局部投影方法。该方法不需潜在动力学系统的先验知识,符合工程实用的要求。通过实验结果表明这种方法对混沌信号去噪很有效。 相似文献