全文获取类型
收费全文 | 1019篇 |
免费 | 19篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 113篇 |
综合类 | 2篇 |
化学工业 | 282篇 |
金属工艺 | 27篇 |
机械仪表 | 49篇 |
建筑科学 | 25篇 |
能源动力 | 77篇 |
轻工业 | 93篇 |
水利工程 | 1篇 |
石油天然气 | 2篇 |
无线电 | 54篇 |
一般工业技术 | 163篇 |
冶金工业 | 30篇 |
原子能技术 | 40篇 |
自动化技术 | 83篇 |
出版年
2023年 | 4篇 |
2022年 | 9篇 |
2021年 | 15篇 |
2020年 | 8篇 |
2019年 | 9篇 |
2018年 | 10篇 |
2017年 | 17篇 |
2016年 | 21篇 |
2015年 | 16篇 |
2014年 | 33篇 |
2013年 | 75篇 |
2012年 | 38篇 |
2011年 | 55篇 |
2010年 | 46篇 |
2009年 | 42篇 |
2008年 | 57篇 |
2007年 | 52篇 |
2006年 | 36篇 |
2005年 | 36篇 |
2004年 | 38篇 |
2003年 | 47篇 |
2002年 | 29篇 |
2001年 | 22篇 |
2000年 | 20篇 |
1999年 | 28篇 |
1998年 | 17篇 |
1997年 | 23篇 |
1996年 | 12篇 |
1995年 | 17篇 |
1994年 | 14篇 |
1993年 | 12篇 |
1992年 | 8篇 |
1991年 | 10篇 |
1990年 | 13篇 |
1989年 | 5篇 |
1988年 | 8篇 |
1987年 | 15篇 |
1986年 | 12篇 |
1985年 | 13篇 |
1984年 | 15篇 |
1983年 | 11篇 |
1982年 | 13篇 |
1981年 | 7篇 |
1980年 | 15篇 |
1979年 | 7篇 |
1978年 | 10篇 |
1977年 | 4篇 |
1976年 | 6篇 |
1975年 | 2篇 |
1969年 | 2篇 |
排序方式: 共有1041条查询结果,搜索用时 15 毫秒
71.
The s-shaped growth curves of detected software errors can be observed in software testing. The delayed s-shaped and inflection s-shaped software reliability growth models based on a nonhomogeneous Poisson process are discussed. The software reliability growth types of the models are investigated in terms of the error detection rate per error. In addition, a viable method for the software quality assessment, which integrates the capture-recapture method and the models above, is discussed, and its application to actual test data is illustrated. 相似文献
72.
Dynamic pH junction is an on-line preconcentration method in capillary electrophoresis (CE) based on electrokinetic focusing of weakly ionic analytes with in large sample volumes in a multisection electrolyte system. In this report, experiments and computer simulations were performed to gain a better insight of the analyte focusing mechanism when a dynamic pH junction was used. A computer program, SIMUL, was used to simulate the band-narrowing process of a group for phenol derivatives under optimized buffer conditions, which were compared with experimental results. Computer simulations revealed the formation of a sharp moving pH boundary within the sample zone causing efficient focusing of long plugs of weakly acidic analytes based on their pKa. These studies offered useful information for understanding the band-narrowing process by control of the depth and lifetime of the moving pH boundary as a function of analyte pKa, sample pH, and injection length. The change in pH of the sample within the capillary was also estimated by measuring the absorbances of an analyte at two different wave-lengths. Optimization of analyte focusing resulted in enhanced detection responses of about 60-450-fold in terms of peak heights for some phenol derivatives' relation to conventional injections. Dynamic pH junction represents a novel approach to control band dispersion (peak width) and selectivity (mobility) of specific analytes for high-resolution CE separations. 相似文献
73.
Practical Reliability and Maintainability Analysis Tool for an Open Source Cloud Computing 下载免费PDF全文
Yoshinobu Tamura Shigeru Yamada 《Quality and Reliability Engineering International》2016,32(3):909-920
We focus on a cloud computing environment by using open source softwares such as OpenStack and Eucalyptus because of the unification management of data and low cost. A cloud computing is attracting attention as a network service to share the computing resources, that is, networks, servers, storage, applications, and services. We propose jump diffusion models based on stochastic differential equations in order to consider the interesting aspect of the provisioning process. Especially, the reliability and maintainability analysis tool for cloud computing is developed in this paper. Also, we analyze actual data to show numerical illustrations of application of the software analysis tool considering the characteristics of cloud computing. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
74.
Randeep Rakwal Ganesh Kumar Agrawal Junko Shibato Tetsuji Imanaka Satoshi Fukutani Shigeru Tamogami Satoru Endo Sarata Kumar Sahoo Yoshinori Masuo Shinzo Kimura 《International journal of molecular sciences》2009,10(3):1215-1225
We report molecular changes in leaves of rice plants (Oryza sativa L. - reference crop plant and grass model) exposed to ultra low-dose ionizing radiation, first using contaminated soil from the exclusion zone around Chernobyl reactor site. Results revealed induction of stress-related marker genes (Northern blot) and secondary metabolites (LC-MS/MS) in irradiated leaf segments over appropriate control. Second, employing the same in vitro model system, we replicated results of the first experiment using in-house fabricated sources of ultra low-dose gamma (γ) rays and selected marker genes by RT-PCR. Results suggest the usefulness of the rice model in studying ultra low-dose radiation response/s. 相似文献
75.
76.
Md. Mahbubul Alam Shigeru Matsuob Kenbu Teramotob Toshiaki Setoguchib Heuy-Dong Kim 《Journal of Mechanical Science and Technology》2007,21(9):1398-1407
A new passive control technique of cavity-induced pressure oscillations has been investigated numerically for a supersonic
two-dimensional flow over open rectangular cavities at Mac h number 1.83 at the cavity entrance. A subcavity on the front
wall of the cavity covered by a flat plate was evaluated for the effectiveness of controlling cavity-induced acoustic oscillations.
The results showed that sub-cavity is very effective in reducing cavity-induced pressure oscillations. The results also showed
that the resultant amount of attenuation of cavity-induced pressure oscillations was dependent on the length and thickness
of the flat plate, and also on the depth of the sub-cavity used as an oscillation suppressor. 相似文献
77.
Shigeru Yamada Yasuyoshi Kurokawa Shinsuke Miyajima Makoto Konagai 《Nanoscale research letters》2014,9(1):246
The solar cell structure of n-type poly-silicon/5-nm-diameter silicon nanocrystals embedded in an amorphous silicon oxycarbide matrix (30 layers)/p-type hydrogenated amorphous silicon/Al electrode was fabricated on a quartz substrate. An open-circuit voltage and a fill factor of 518 mV and 0.51 in the solar cell were obtained, respectively. The absorption edge of the solar cell was 1.49 eV, which corresponds to the optical bandgap of the silicon nanocrystal materials, suggesting that it is possible to fabricate the solar cells with silicon nanocrystal materials, whose bandgaps are wider than that of crystalline silicon.
PACS
85.35.Be; 84.60.Jt; 78.67.Bf 相似文献78.
Matemu AO Nakamura K Kayahara H Murasawa H Katayama S Nakamura S 《Journal of food science》2011,76(6):M299-M304
Abstract: Peptide mixtures prepared from soybean β‐conglycinin (7S‐peptides) were acylated with saturated fatty acids of different chain length (6C‐18C) in order to improve their antiviral activity against Feline calicivirus (FCV) strain F9 which is a typical norovirus surrogate. Among the fatty acids varieties, it was revealed that 7S‐peptides acylated with myristic and palmitic acids potently inhibited FCV replication. Myristorylation and palmitoylation of 7S‐peptides kept host cells viability at 91.51% and 98.90%, respectively. The infectivity of FCV on Crandell–Reese feline kidney cells was further determined after exposure of initial titer of 106.47 TCID50/mL. Myristoylated and palmitoylated 7S‐peptides significantly (P < 0.006) reduced FCV infectivity as compared to native 7S‐peptides. Native 7S‐peptides showed 25% FCV inhibitory activity while myristoylated and palmitoylated 7S‐peptides exhibited 98.59% and 99.98% reduction in FCV infectivity, respectively. Myristoylated and palmitoylated 7S‐peptides demonstrated higher anti‐FCV activity in a wide range of concentration with complete reduction at 25 μg/mL. Surface hydrophobicity was significantly (P < 0.05) increased after attachment of long hydrocarbon fatty acids to 7S‐peptides as supported by changes in fluorescence intensity. Enzymatic hydrolysis together with acylation will give an insight into surface and physiological functional lipopeptides derived from soy β‐conglycinin. 相似文献
79.
We describe the electrochemical detection of DNA methylation through the direct oxidation of both 5-methylcytosine (mC) and cytosine (C) in 5'-CG-3' sequence (CpG) oligonucleotides using a sputtered nanocarbon film electrode after digesting a longer CpG oligonucleotide with endonuclease P1. Direct electrochemistry of the longer CpG oligonucleotides was insufficient for obtaining the oxidation currents of these bases because the CG rich sequence inhibited the direct oxidation of each base in the longer CpG oligonucleotides, owing to the conformational structure and its very low diffusion coefficient. To detect C methylation with better quantitativity and sensitivity in the relatively long CpG oligonucleotides, we successfully used an endonuclease P1 to digest the target CpG oligonucleotide and yield an identical mononucleotide 2'-deoxyribonucleoside 5'-monophosphate (5'-dNMP). Compared with results obtained without P1 treatment, we achieved 4.4 times higher sensitivity and a wider concentration range for mC detection with a resolution capable of detecting a subtle methylated cytosine difference in the CpG oligonucleotides (60mer). 相似文献
80.
Vincent Lijo Heuy Dong Kim Toshiaki Setoguchi Shigeru Matsuo 《Journal of Mechanical Science and Technology》2011,25(2):341-347
When sonic nozzles of significantly smaller diameter are used as standard flow meters, the critical backpressure ratio is
affected by the boundary layer at the nozzle throat. It is known that, as the flow pathway is complicated in actual valves,
the critical pressure ratio differs from the ideal value. However, the effect of the boundary layer thickness on choking criteria
is still controversial. Choking phenomenon in a sonic nozzle fitted with a straight circular pipe of variable length is investigated
numerically and the results are compared with experimental and theoretical ones. The results show that the actual critical
pressure ratio is less than the ideal value and it decreases with increase in pipe length. The effect of boundary layer thickness
on main flow Mach number is also made clear in this work. In addition, sonic conductance and pressure loss in actual viscous
flows computed are compared with the ISO 6358 standard. 相似文献