全文获取类型
收费全文 | 42702篇 |
免费 | 1878篇 |
国内免费 | 1513篇 |
专业分类
电工技术 | 1451篇 |
技术理论 | 4篇 |
综合类 | 1065篇 |
化学工业 | 6074篇 |
金属工艺 | 3102篇 |
机械仪表 | 2118篇 |
建筑科学 | 1781篇 |
矿业工程 | 554篇 |
能源动力 | 1411篇 |
轻工业 | 2204篇 |
水利工程 | 437篇 |
石油天然气 | 1470篇 |
武器工业 | 132篇 |
无线电 | 5313篇 |
一般工业技术 | 9152篇 |
冶金工业 | 4849篇 |
原子能技术 | 475篇 |
自动化技术 | 4501篇 |
出版年
2024年 | 56篇 |
2023年 | 335篇 |
2022年 | 594篇 |
2021年 | 919篇 |
2020年 | 672篇 |
2019年 | 746篇 |
2018年 | 965篇 |
2017年 | 958篇 |
2016年 | 989篇 |
2015年 | 1022篇 |
2014年 | 1442篇 |
2013年 | 2722篇 |
2012年 | 2020篇 |
2011年 | 2652篇 |
2010年 | 2066篇 |
2009年 | 2280篇 |
2008年 | 2268篇 |
2007年 | 2245篇 |
2006年 | 2124篇 |
2005年 | 1930篇 |
2004年 | 1456篇 |
2003年 | 1377篇 |
2002年 | 1267篇 |
2001年 | 1166篇 |
2000年 | 1217篇 |
1999年 | 1306篇 |
1998年 | 1991篇 |
1997年 | 1497篇 |
1996年 | 1333篇 |
1995年 | 873篇 |
1994年 | 749篇 |
1993年 | 583篇 |
1992年 | 407篇 |
1991年 | 382篇 |
1990年 | 280篇 |
1989年 | 263篇 |
1988年 | 195篇 |
1987年 | 134篇 |
1986年 | 102篇 |
1985年 | 94篇 |
1984年 | 56篇 |
1983年 | 47篇 |
1982年 | 56篇 |
1981年 | 51篇 |
1980年 | 31篇 |
1979年 | 18篇 |
1978年 | 19篇 |
1977年 | 19篇 |
1976年 | 31篇 |
1975年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
921.
Jia X Gan C Xiao K He W Zhang T Huang C Wu X Luo G Wang X Hu J Tan J Zhang X Larsen PM Wu J 《Proteomics. Clinical applications》2009,3(6):694-704
Acute allograft rejection has been recognized as a major impediment to improved success in renal transplantation. Timely detection and control of rejection are very important for the improvement in long-term renal allograft survival. Thus, biomarkers for early diagnosis of acute rejection are required urgently to clinical medication. This study seeks to search for such biomarker candidates by comparing patients' pre-treatment urinary protein profiling with their post-treatment urinary protein profiling. A total of 15 significantly and consistently down-regulated protein candidates were identified. Among them, alpha-1-antichymotrypsin precursor (AACT), tumor rejection antigen gp96 (GP96) and Zn-Alpha-2-Glycoprotein (ZAG) were selected for further analysis. The results indicated that Western Blot assay of AACT, GP96 and ZAG had advanced the diagnosis time of acute renal rejection by 3 days, compared with current standard clinical observation and laboratory examination. Furthermore, the double-blind detection revealed that the accuracy, sensitivity and specificity of the diagnosis of acute renal rejection of AACT, GP96 and ZAG were 66.67%/100%/60%, 83.33%/100%/80% and 66.67%/100%/60%, respectively, and 100%/100%/100% in combination. In conclusion, urinary protein AACT, GP96 and ZAG could be a set of potential biomarkers for early non-invasive diagnosis of the acute rejection after renal transplantation. 相似文献
922.
D. Caliste Y. Pouillon M.J. Verstraete V. Olevano X. Gonze 《Computer Physics Communications》2008,179(10):748-758
We present a library of routines whose main goal is to read and write exchangeable files (NetCDF file format) storing electronic structure and crystallographic information. It is based on the specification agreed inside the European Theoretical Spectroscopy Facility (ETSF). Accordingly, this library is nicknamed ETSF_IO. The purpose of this article is to give both an overview of the ETSF_IO library and a closer look at its usage. ETSF_IO is designed to be robust and easy to use, close to Fortran read and write routines. To facilitate its adoption, a complete documentation of the input and output arguments of the routines is available in the package, as well as six tutorials explaining in detail various possible uses of the library routines.
Program summary
Program title: ETSF_IOCatalogue identifier: AEBG_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEBG_v1_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Gnu Lesser General Public LicenseNo. of lines in distributed program, including test data, etc.: 63 156No. of bytes in distributed program, including test data, etc.: 363 390Distribution format: tar.gzProgramming language: Fortran 95Computer: All systems with a Fortran95 compilerOperating system: All systems with a Fortran95 compilerClassification: 7.3, 8External routines: NetCDF, http://www.unidata.ucar.edu/software/netcdfNature of problem: Store and exchange electronic structure data and crystallographic data independently of the computational platform, language and generating softwareSolution method: Implement a library based both on NetCDF file format and an open specification (http://etsf.eu/index.php?page=standardization) 相似文献923.
化学虚拟实验中序列化技术的应用与研究 总被引:1,自引:0,他引:1
虚拟实验室是教育领域的一个研究热点,其中实验的存储是系统一个十分重要的功能模块。文中以采用VC 和OpenGL技术开发的中学化学实验仿真系统(CVExperiment)为例,详细介绍比较复杂的对象的序列化,并根据对象之间的不同关系,提出不同的序列化方法。 相似文献
924.
这是一个被人誉为资讯爆炸的时代,这是一个他信力接近冰点的时代……生活在信息时代的人们,每天都接收到众多资讯,这些资讯涵盖大众生活的各个方面,商业、政治、体育、生活等。而大大小小的媒体每天将最新的新闻与资讯传达给大众时,也夹杂着它们对于新闻事件的观点和态度。 相似文献
925.
926.
为了准确、可靠地配准多模态医学图像,提出了一种基于互信息的全局优化配准算法。该算法首先提取出目标物体的外轮廓面,再用迭代最近点方法初步对齐图像;然后用确定性的全局优化方法—Dividing Rectangles搜索归一化互信息的全局最优解。该算法利用图像的特征信息,为Dividing Rectangles方法提供了一个较好的初始配准位置,并充分利用了Dividing Rectangles方法在小范围内的高效搜索能力。实验结果表明,对于3维人体脑部数据,该算法配准精度高、速度快,而且有效地避免了配准过程中出现的局部极值。 相似文献
927.
基于光纤环网的隧道火灾监控系统研究 总被引:1,自引:1,他引:0
文章对基于光纤环网的隧道群火灾报警系统进行研究,分析了其优缺点,提出了解决办法,并完成改造,应用于实际. 相似文献
928.
MBS对PVC的增韧作用及其机理的探讨 总被引:4,自引:0,他引:4
本文通过扫描电镜观察了PVC/MBS共混物银纹的发展和冲击断面形貌,并测定了银纹体的密度变化。采用光散射法分析银纹和剪切带比例。合成不同玻璃化温度的MBS考察它对PVC增韧的影响,进行有关MBS对PVC增韧机理的探讨。 相似文献
929.
930.
Several metal complexes [(FeII(DPAH)2 (DPAH2 = 2,6-dicarboxyl pyridine), FeII(PA)2 (PAH = picolinic acid), FeII(bpy)2(2+), FeII(OPPh3)4(2+), (Cl8TPP)FeIIIX (X = Cl, OH, SCH2Ph) [Cl8TPP = tetrakis (2,6-dichlorophenyl)porphyrin], (TPP) FeIIICl (TPP = tetraphenylporphyrin), and CuI(tpy)2+ (typ = 2,2'-6,2"-terpyridine)] in combination with one of several reductants [DH2; PhNHNHPh (mimic of dihydroflavin), PhNHNH2, ascorbic acid (H2asc), and PhCH2SH (model ligand for cysteine residue)] catalytically activate O2 (1 atm) for the hydroxylation of saturated hydrocarbons (e.g. c-C6H12-->c-C6H11OH). This chemistry closely parallels that of cytochrome P-450 proteins, and both appear to involve a Fenton-like reactive intermediate), [LxFeOOH(DH)]. With cyclohexane as the substrate the dominant product is its ketone (as well as significant amounts of its hydroperoxide). 1,4-Cyclohexadiene (with two double-allylic carbon centers) undergoes dehydrogenation to give benzene, but also yields substantial amounts of phenol via ketonization of an allylic carbon. The 1:1 FeII(bpy)2(2+)/(PhNHNH2 or H2asc), FeII(PA)2/H2asc, and (Cl8TPP)FeIIICl/PhNHNH2 combinations initiate the autoxidation of 1,4-cyclohexadiene with turnover numbers (moles of product per mole of reductant) from 71 to 26, respectively (alpha-tocophenol reduces the turnover numbers by 20-80%). With respect to aerobic biology, the present results indicate that dysfunctional transition metals (degradation products of metalloproteins) in combination with biological reductants activate O2 for reaction with organic substrates. The level of activation is similar to that for Fenton reagents and cytochrome P-450 hydroxylases. Hence, dysfunctional transition metals, reductants, and O2 are a hazardous combination within a biological matrix. 相似文献