全文获取类型
收费全文 | 1245篇 |
免费 | 97篇 |
国内免费 | 32篇 |
专业分类
电工技术 | 118篇 |
综合类 | 116篇 |
化学工业 | 118篇 |
金属工艺 | 143篇 |
机械仪表 | 139篇 |
建筑科学 | 268篇 |
矿业工程 | 55篇 |
能源动力 | 41篇 |
轻工业 | 47篇 |
水利工程 | 25篇 |
石油天然气 | 34篇 |
武器工业 | 18篇 |
无线电 | 55篇 |
一般工业技术 | 72篇 |
冶金工业 | 34篇 |
原子能技术 | 10篇 |
自动化技术 | 81篇 |
出版年
2024年 | 4篇 |
2023年 | 17篇 |
2022年 | 24篇 |
2021年 | 53篇 |
2020年 | 28篇 |
2019年 | 17篇 |
2018年 | 25篇 |
2017年 | 38篇 |
2016年 | 35篇 |
2015年 | 37篇 |
2014年 | 101篇 |
2013年 | 66篇 |
2012年 | 87篇 |
2011年 | 90篇 |
2010年 | 69篇 |
2009年 | 90篇 |
2008年 | 76篇 |
2007年 | 90篇 |
2006年 | 80篇 |
2005年 | 69篇 |
2004年 | 52篇 |
2003年 | 39篇 |
2002年 | 25篇 |
2001年 | 45篇 |
2000年 | 25篇 |
1999年 | 14篇 |
1998年 | 19篇 |
1997年 | 9篇 |
1996年 | 13篇 |
1995年 | 8篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1982年 | 3篇 |
1964年 | 1篇 |
排序方式: 共有1374条查询结果,搜索用时 46 毫秒
41.
为保证整车外观颜色的一致性,提高客户的满意度,将外饰件与车身色差控制在很小范围内,制定系统而有效的评价标准与管理办法尤为重要。结合现生产,从实际情况出发,对控制车身色差问题做系统分析,并运用SPC统计方法对日常色差进行监控管理,有效抑制了色差问题的发生。 相似文献
42.
冲(钻)孔桩施工中出现桩侧土层泥皮过厚从而严重影响基桩承载力。为解决这个问题,采取泥浆制备、成孔、清孔和刷孔壁泥皮等4道工序。如在地质特殊地区采用旋挖钻机,可以成功地完成桩基施工 相似文献
43.
Muhammad Qasim Marius Wrage Bjrn Nüse Jochen Mattner 《International journal of molecular sciences》2022,23(2)
The clinical symptoms of shigellosis, a gastrointestinal infection caused by Shigella spp. range from watery diarrhea to fulminant dysentery. Endemic infections, particularly among children in developing countries, represent the majority of clinical cases. The situation is aggravated due to the high mortality rate of shigellosis, the rapid dissemination of multi-resistant Shigella strains and the induction of only serotype-specific immunity. Thus, infection prevention due to vaccination, encompassing as many of the circulating serotypes as possible, has become a topic of interest. However, vaccines have turned out to be ineffective so far. Outer membrane vesicles (OMVs) are promising novel targets for vaccination. OMVs are constitutively secreted by Gram-negative bacteria including Shigella during growth. They are composed of soluble luminal portions and an insoluble membrane and can contain toxins, bioactive periplasmic and cytoplasmic (lipo-) proteins, (phospho-) lipids, nucleic acids and/or lipopolysaccharides. Thus, OMVs play an important role in bacterial cell–cell communication, growth, survival and pathogenesis. Furthermore, they modulate the secretion and transport of biomolecules, the stress response, antibiotic resistance and immune responses of the host. Thus, OMVs serve as novel secretion machinery. Here, we discuss the current literature and highlight the properties of OMVs as potent vaccine candidates because of their immunomodulatory, antigenic and adjuvant properties. 相似文献
44.
Sachiko Kaidzu Tsutomu Okuno Masaki Tanito Akihiro Ohira 《International journal of molecular sciences》2022,23(1)
The effects of visible light, from short to long wavelengths, on the retina were investigated functionally and histologically. The left eyes of Sprague–Dawley albino rats (6-weeks old, n = 6 for each wavelength) were exposed to seven narrow-band wavelengths (central wavelengths, 421, 441, 459, 501, 541, 581, and 615 nm) with bandwidths of 16 to 29 nm (half bandwidth, ±8–14.5 nm) using a xenon lamp source with bandpass filters at the retinal radiant exposures of 340 and 680 J/cm2. The right unexposed eyes served as controls. Seven days after exposure, flash electroretinograms (ERGs) were recorded, and the outer nuclear layer (ONL) thickness was measured. Compared to the unexposed eyes, significant reductions in the a- and b-wave ERG amplitudes were seen in eyes exposed to 460-nm or shorter wavelengths of light. The ONL thickness near the optic nerve head also tended to decrease with exposure to shorter wavelengths. The decreased ERG amplitudes and ONL thicknesses were most prominent in eyes exposed to 420-nm light at both radiant exposures. When the wavelengths were the same, the higher the amount of radiant exposure and the stronger the damage. Compared to the unexposed eyes, the a- and b-waves did not decrease significantly in eyes exposed to 500-nm or longer wavelength light. The results indicate that the retinal damage induced by visible light observed in albino rats depends on the wavelength and energy level of the exposed light. 相似文献
45.
对冀北地区住宅围护结构节能方面进行了一系列的研究,并提出了一些可行性建议. 相似文献
46.
针对车门外板轮廓翻边R角(后门C柱侧)、车门外板轮廓整形R角(后门B柱侧)锐化进行工艺方案分析及实物论证,并针对车门外板单件刚性差,回弹控制难度大的特点,调整冲压工艺方案,利用AutoFrom软件进行回弹模拟分析验算,并在模具开发中进行应用,经实物验证调整方案有效。 相似文献
47.
48.
人眼3D肌肉控制模型 总被引:3,自引:0,他引:3
根据解剖学原理及人眼运动特征,提出了一种人眼3D肌肉控制模型.该模型由内部模型和外部模型组成,其3D运动由3类共8条肌肉控制.模型建模及驱动比较方便,并已在PC机上进行了模拟.模拟结果表明,人眼模型逼真,可较好地模拟人眼运动及表情. 相似文献
49.
随着光伏发电并网规模的扩大,由其换流器控制系统动态特性引起的小干扰稳定性问题愈加突出。而单台光伏发电单元容量较小,故并网光伏发电系统中往往包含大量光伏发电单元,系统模型阶数较高,极大地增加了稳定性分析的复杂程度。因此,为提出一种较为简单有效的稳定性判别方法,文中首先通过时间尺度分解建立并网光伏发电系统在直流电压时间尺度下的小干扰稳定分析降阶模型;随后,在该模型的基础上,由劳斯-赫尔维茨判据推导得到系统的小干扰稳定判据,并结合判据分析直流电压时间尺度下影响系统小干扰稳定性的关键因素,辨识出3个影响稳定性的不利因素:重负荷、弱连接、不恰当的控制参数设置;最后,通过仿真算例验证该稳定性判据的正确性和有效性。结果表明:所得出的稳定性判据能有效评估并网光伏发电系统在直流电压时间尺度下的小干扰稳定性,并且不需要建立复杂高阶的系统模型,极大地简化了计算和分析过程。 相似文献
50.
Molly C. Benthal Alex S. McKeown Timothy W. Kraft 《International journal of molecular sciences》2022,23(7)
We investigated the etiology of decreased cone-driven vision in a light damage (LD) model of retinal degeneration. To induce slow, moderate degeneration, albino rats underwent low-intensity light exposure for 10 days. Electroretinography was utilized to assess physiologic function of the rod- and cone-driven retinal function in LD and control rats. Immunohistochemistry targeting cone arrestin allowed for quantification of cone density and for comparison of the decline in function. Photoreceptor loss was quantified by outer nuclear layer thickness decreases, as observed by optical coherence tomography and histology. The LD rats showed decreased rod- and cone-driven function with partial recovery 30 days after cessation of light exposure. In addition, LD rats showed decreased cone photoreceptor densities in the central retinal region compared to control rats. Our results demonstrate that the loss of cone-driven visual function induced by light damage is at least partially due to the death of cone photoreceptors. 相似文献