全文获取类型
收费全文 | 11390篇 |
免费 | 2333篇 |
国内免费 | 1244篇 |
专业分类
电工技术 | 532篇 |
综合类 | 1345篇 |
化学工业 | 352篇 |
金属工艺 | 235篇 |
机械仪表 | 688篇 |
建筑科学 | 342篇 |
矿业工程 | 238篇 |
能源动力 | 111篇 |
轻工业 | 168篇 |
水利工程 | 116篇 |
石油天然气 | 315篇 |
武器工业 | 1136篇 |
无线电 | 4541篇 |
一般工业技术 | 922篇 |
冶金工业 | 374篇 |
原子能技术 | 369篇 |
自动化技术 | 3183篇 |
出版年
2024年 | 45篇 |
2023年 | 253篇 |
2022年 | 494篇 |
2021年 | 555篇 |
2020年 | 515篇 |
2019年 | 443篇 |
2018年 | 399篇 |
2017年 | 435篇 |
2016年 | 544篇 |
2015年 | 647篇 |
2014年 | 829篇 |
2013年 | 749篇 |
2012年 | 990篇 |
2011年 | 1067篇 |
2010年 | 830篇 |
2009年 | 823篇 |
2008年 | 759篇 |
2007年 | 924篇 |
2006年 | 667篇 |
2005年 | 586篇 |
2004年 | 467篇 |
2003年 | 410篇 |
2002年 | 311篇 |
2001年 | 257篇 |
2000年 | 212篇 |
1999年 | 164篇 |
1998年 | 114篇 |
1997年 | 89篇 |
1996年 | 98篇 |
1995年 | 53篇 |
1994年 | 50篇 |
1993年 | 40篇 |
1992年 | 30篇 |
1991年 | 22篇 |
1990年 | 20篇 |
1989年 | 14篇 |
1988年 | 10篇 |
1987年 | 10篇 |
1986年 | 6篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1965年 | 2篇 |
1964年 | 2篇 |
1962年 | 2篇 |
1961年 | 2篇 |
1959年 | 5篇 |
1956年 | 3篇 |
1954年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
CFTR氯离子通道是目前国际上新兴的治疗分泌型腹泻的分子药靶,CFTR抑制剂通过阻断离子通道的过度分泌来治疗腹泻症状。由于其抑制剂极为稀少,因此CFTR抑制剂的筛选工作是相关领域中最基础、最关键的环节。天然产物兼具结构和生物活性的多样性,在新药和先导化合物的发现中起着重要作用,是药物开发的主要来源,而食品药品来源的天然产物更因为对人体安全无毒副作用而倍受青睐。食品药品来源的CFTR氯离子通道抑制剂对于CFTR相关的腹泻等疾病的机理研究和治疗具有重要价值,同时也为天然产物资源用于现代药物发现提供了依据。 相似文献
32.
《International Journal of Hydrogen Energy》2020,45(30):15358-15365
Among the different coatings developed for proton exchange membrane fuel cell steel bipolar plate, nitride-based coatings present several advantages compared to gold or polymeric coating: high chemical stability, low interfacial contact resistance and reasonable cost. In this work, 50 nm thick chromium nitride coatings are deposited by reactive magnetron sputtering on 316L stainless steel foil. They are optimized to fulfill the Department of Energy targets in terms of interfacial contact resistance (ICR) and corrosion resistance, with values of 8.4 mΩ cm−2 (at 100 N cm−2) and 0.10 μA cm−2 (in 0.6 M H2SO4 solution at 0.48 Vvs. SCE potential) respectively. Moreover, they retain their excellent properties after high deformation (biaxial deformation of 20% in x-axis and 5% in y-axis), giving the possibility to achieve, in line, the stamping of a bipolar plate from a coated foil. The etching of the substrate, prior to the coating deposition, appears to be determinant to obtain low and stable corrosion current and ICR. The removing of interfacial oxyde leads to better coating adhesion and improves the corrosion resistance and electrical conductivity. The enhancement of the properties (low ICR and high corrosion resistance) is durable, with no signicant change of the ICR value up to 200 days after deposition. 相似文献
33.
34.
叶飞 《气象水文海洋仪器》2020,(1):1-4
文章选用2017-12-13的青浦站和南通站体扫数据和单站格点CAPPI数据,利用时空一致性匹配法和单站格点数据等距离线法对两站雷达回波强度差异情况进行了研究,并分析了两种算法可能存在的误差,结果表明:单站格点数据等距离线法要优于时空一致性匹配法,更适用于单部雷达体扫数据的相邻雷达回波差异对比;在雷达基数据正确的情况下,时空一致性匹配法误差主要来源于做不到真正的时空匹配一致,格点数据等距离线法误差主要来源于生成格点数据时插值算法不完善。 相似文献
35.
JONG HWAN SUNG 《Biocell》2022,46(5):1177-1180
Organ-on-a-chip technology aims to reproduce the key physiological features of human organs and tissues, even complex actions of multi-organ interaction. While organ-on-a-chips at single-organ level has made notable achievement during the last decade, multi-organ-on-a-chips, which manifests unique advantages, has started gathering attention only recently. In this viewpoint, we discuss the current status of organ-on-a-chip technology, with a specific emphasis on multi-organ-on-a-chip. Key technological advances contributing to the maturation of the field, and challenges that need to be addressed before wider adoption in relevant fields are discussed. We will share our perspectives on how the multi-organ-on-a-chip can improve the drug development process. 相似文献
36.
We investigated the diversity and composition of microflora in feces of Lycopus lucidus Turcz.-fed mice. In
addition, we evaluated the production of major cytokines (Interleukin-6 and -10) which are related to inflammation
and fatty acid composition of several tissues. 16S ribosomal DNA sequencing-based microbiome taxonomic profiling
analysis was performed utilizing the EzBioCloud data base. Male mice fed on L. lucidus showed a significantly
reduced number of lactic acid bacteria and coliform in the feces compared with the control group (p < 0.05). 16S
rDNA sequencing analysis of fecal samples showed that L. lucidus supplementation decreased the community of
harmful microflora (Enterobacteriaceae including Escherichia coli and Bacteroides sp.) in feces compared with the
control group (p < 0.05). There were no significant differences in mRNA expression of cytokine IL-6 and IL-10
between the control and L. lucidus fed groups. The fecal fatty acid composition in the L. lucidus group had
percentages of 4:0, 6:0, 8:0 and 10:0 in the intestine but those short chain fatty acids were not detected in the control
group. Our results showed that L. lucidus supplementation influenced gut environment by decreasing harmful
microflora and increased the percentages of several short fatty acids. 相似文献
37.
Hazelnut husk brown rot has been identified as a new disease in Liaoning Province in recent years. The objective of this study as to identify the pathogen. [Method] In this study, a standard sample of hazelnut husk brown rot was collected from Songmudao Base in Dalian City, Liaoning Province. The pathogen was identified by the studies of the morphology, pathogenicity, and analyses of ITS and LSU sequences. The pathogen was isolated and purified, which was confirmed by Koch’s postulates. The symptoms after inoculation were the same as those collected directly from a diseased tree, which showed that it was the pathogenic fungus. The cultural characteristics and conidia and the morphology of the pathogenic fungi were similar to those of Botrytis cinerea’s. The ITS sequences and LSU sequences were compared to the associated strain sequences in GenBank, with 100% identity to Botrytis cinerea (GenBank accession number: MN589848.1) and Botrytis cinerea (GenBank accession number: KU140653.1), respectively. The infection status of the pathogen on the hazelnut husks was also observed. The studies suggested that the pathogen leading to the hazelnut husk brown rot as a new disease in Liaoning Province was Botrytis cinerea. 相似文献
38.
39.
运动目标图像提取有助于通过计算机视觉实现复杂变化背景下的图像细节分析,现有图像提取方法通常针对某一类图像作为研究对象,致使应用场合受到一定限制。针对运动目标图像的提取应用,提出了改进Renyi熵的运动目标图像提取方法。首先利用直方图对运动图像的YCbCr颜色概率进行估算,根据图像YCbCr颜色计算Renyi熵,然后设计相应的目标函数来确定阈值,并结合中值处理提高算法的抗噪声性能,最后对颜色的Y、Cb与Cr通道分割得到原始中心点,利用迭代处理更新中心点,并搜索出像素的边界阈值,从而实现运动目标图像的提取。通过仿真,分别从提取时间、计算熵值、以及目标图像识别率多个方面进行比较验证,证明了提出的改进Renyi熵的运动目标图像提取方法能够有效应对运动图像复杂多变的背景,提高了处理速度与提取准确度,具有较好的抗干扰能力。 相似文献
40.
随着煤炭开采逐渐向深部转移,巷道围岩变形越来越严重。分析了深埋巷道围岩变形及支护技术,对研究巷道进行了三轴抗拉试验,得到煤和岩石力学参数,采用结构梁和弹性力学分析了巷道围岩变形,为模型分析提供了理论基础,然后采用FLAC^3D数值模拟软件,分析了巷道变形位移,与现场实测相比,数值模拟能够较好地模拟煤矿巷道实际变形情况。研究能够为巷道参数设计提供借鉴。 相似文献