全文获取类型
收费全文 | 931篇 |
免费 | 43篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 8篇 |
化学工业 | 235篇 |
金属工艺 | 64篇 |
机械仪表 | 11篇 |
建筑科学 | 13篇 |
能源动力 | 51篇 |
轻工业 | 45篇 |
水利工程 | 13篇 |
石油天然气 | 2篇 |
无线电 | 144篇 |
一般工业技术 | 200篇 |
冶金工业 | 100篇 |
原子能技术 | 5篇 |
自动化技术 | 87篇 |
出版年
2024年 | 3篇 |
2023年 | 8篇 |
2022年 | 19篇 |
2021年 | 24篇 |
2020年 | 15篇 |
2019年 | 21篇 |
2018年 | 28篇 |
2017年 | 27篇 |
2016年 | 30篇 |
2015年 | 26篇 |
2014年 | 31篇 |
2013年 | 90篇 |
2012年 | 40篇 |
2011年 | 48篇 |
2010年 | 38篇 |
2009年 | 35篇 |
2008年 | 44篇 |
2007年 | 40篇 |
2006年 | 47篇 |
2005年 | 35篇 |
2004年 | 26篇 |
2003年 | 18篇 |
2002年 | 20篇 |
2001年 | 12篇 |
2000年 | 18篇 |
1999年 | 14篇 |
1998年 | 31篇 |
1997年 | 21篇 |
1996年 | 24篇 |
1995年 | 11篇 |
1994年 | 13篇 |
1993年 | 8篇 |
1992年 | 3篇 |
1991年 | 12篇 |
1990年 | 9篇 |
1989年 | 13篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 6篇 |
1973年 | 4篇 |
1972年 | 3篇 |
1954年 | 2篇 |
排序方式: 共有978条查询结果,搜索用时 203 毫秒
41.
42.
Rapid detection and quantification of soya bean oil and common sugar in bovine milk using attenuated total reflectance–fourier transform infrared spectroscopy 下载免费PDF全文
Pranita Jaiswal Shyam Narayan Jha Jaspreet Kaur Ramya Hg 《International Journal of Dairy Technology》2018,71(2):292-300
Attenuated total reflectance–Fourier transform infrared spectroscopy, along with chemometrics, were used to detect and quantify soya bean oil (SO) and sugar (CS) adulteration in milk. Bovine milk was artificially adulterated with SO (0.2–2.0%; v/v) and CS (1–10%; w/v) separately. Spectra revealed significant differences in specific wavenumber regions (SO: 1450–1250 cm?1; CS: 1200–900 cm?1). Soya bean oil adulteration was best predicted in wavenumber range of 1262–1164 cm?1, using partial least square regression (coefficient of determination (R2: 0.90 and 0.88 for calibration and validation, respectively). Common sugar adulteration was best predicted in wavenumber range of 1010–910 cm?1 (R2: 0.99 for calibration and validation) using partial least square. 相似文献
43.
A multistage serial production system is considered in the present paper. A generalized model has been developed with the use of probabilistic demand situations for the end product. The demand situations considered are binomial, exponential, lognormal and Poisson. These demand patterns are used as input parameter for various production control policies. The output values for performance parameters are obtained by simulation. The production policies analyzed are Kanban, CONWIP and Hybrid as alternatives for controlling the engineering manufacture. In the presence of several performance measures, it often becomes difficult for the management to select the most appropriate policy. Analytic hierarchy process (AHP) has been implemented for the purpose of selection. Computational results have been reported along with the sensitivity analysis after designing and conducting various experiments. 相似文献
44.
Narayan TK Herman GT 《Journal of the Optical Society of America. A, Optics, image science, and vision》1999,16(3):679-693
Numerical observers are investigated for predicting the outcome of a free-response human observer study involving the detection of simulated pulmonary nodules in images reconstructed from low-dose computed tomography projection data by use of several reconstruction algorithms. A new way of calculating the figure of merit of a numerical observer is proposed wherein the detectability of signals in a particular image depends on the noise properties associated with that image and not the other images in the data set. The resulting variants of numerical observers are found to perform better than their traditional counterparts. In particular, the imagewise variant of the region-of-interest observer is found to predict best the rank ordering of algorithms by human observers for the free-response task. 相似文献
45.
46.
The heptahelical lutropin receptor (LHR) signals primarily via the Gs-adenylyl cyclase pathway and undergoes ligand-mediated receptor desensitization and internalization. A loss-of-function rat LHR mutant was recently described in which a single amino acid residue replacement in exoloop 3, K583E, had no effect on human choriogonadotropin (hCG) binding but essentially abolished signaling. This LHR mutant is a prime candidate for which to study hCG-mediated receptor internalization since it is highly unlikely that an amino acid residue in exoloop 3 , i.e. an extracellular portion of LHR connecting transmembrane helices 6 and 7, could have any direct interaction with Galpha(s), which is located on the cytoplasmic face of the plasma membrane. A method to study endocytosis was adapted that involves concanavalin A binding to the glycoproteins on the cell surface, thus facilitating separation of the plasma membrane fraction from other cellular membrane fractions by sucrose gradient centrifugation. Conditions were used such that a single round of endocytosis could be determined with [125I]hCG. Endocytic rate constants of 0.03 and O min(-1) were obtained for LHR and the mutant, respectively, in transfected human embryonic kidney 293 cells; moreover, internalization of the mutant could not be restored by the addition of 8-Br-cAMP. Thus, the presence of the second messenger cAMP is not sufficient for internalization of ligand-occupied LHR. Rather, it appears that ligand-mediated activation and subsequent internalization of LHR results from an altered conformational state or a conformation-dependent post-ligand binding modification such as phosphorylation. 相似文献
47.
48.
The paper presents numerical simulations and analysis of electrokinetic induced mixing in a microchamber in the presence of a fluctuating electric field. Two microchamber geometries are investigated; one plain and the other with strategically placed microbaffles. Both geometries are tested for two extreme surface conditions: a charged surface with induced electrokinesis and another with a neutral or passive surface. Through order of magnitude analysis and numerical experiments it is found that there is an optimal choice of nondimensional frequency and driving potential which leads to the best mixing characteristics. This is given by the relationship Re(eof)/f*< 5 and the condition that f*= O(1), where Re(eof) is the ratio of electrokinetic forces to viscous forces and f*is the nondimensional frequency. Optimal mixing is shown to occur at Re(eof) = 100 and f*= 30. In all cases, best mixing is found to occur when conditions are favorable for the establishment and sustenance of a rotational cell in the chamber driven by the fluctuating ac current. It is shown that the plain microchamber performs better under conditions of surface neutrality while microbaffles enhance mixing substantially in a charged microchamber. In the presence of a rotational cell, the characteristic time scale for mixing is reduced by 2-3 orders of magnitude compared to plain diffusion and is calculated to be between 5 and 10 s for aqueous buffers. 相似文献
49.
Mandayam Tiru Maj-Britt Tiru Rolf Juhlin 《Journal of the American Oil Chemists' Society》1978,55(4):428-429
A procedure has been developed for the adsorption of oily or solid substrates of low water solubility onto inert carriers having large specific surface areas. This technique improves the handling characteristics of such substrates, enhances the standardization of enzymes, and facilitates separation of a carrier-bound substrate/product from the reaction mixture. 相似文献
50.
Ohne Zusammenfassung 相似文献