全文获取类型
收费全文 | 1199篇 |
免费 | 37篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 67篇 |
综合类 | 3篇 |
化学工业 | 342篇 |
金属工艺 | 25篇 |
机械仪表 | 25篇 |
建筑科学 | 20篇 |
矿业工程 | 1篇 |
能源动力 | 71篇 |
轻工业 | 103篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 77篇 |
一般工业技术 | 226篇 |
冶金工业 | 161篇 |
原子能技术 | 33篇 |
自动化技术 | 85篇 |
出版年
2023年 | 6篇 |
2022年 | 15篇 |
2021年 | 30篇 |
2020年 | 9篇 |
2019年 | 14篇 |
2018年 | 18篇 |
2017年 | 18篇 |
2016年 | 22篇 |
2015年 | 27篇 |
2014年 | 22篇 |
2013年 | 64篇 |
2012年 | 34篇 |
2011年 | 62篇 |
2010年 | 43篇 |
2009年 | 52篇 |
2008年 | 44篇 |
2007年 | 61篇 |
2006年 | 54篇 |
2005年 | 41篇 |
2004年 | 35篇 |
2003年 | 34篇 |
2002年 | 26篇 |
2001年 | 23篇 |
2000年 | 30篇 |
1999年 | 30篇 |
1998年 | 47篇 |
1997年 | 44篇 |
1996年 | 49篇 |
1995年 | 17篇 |
1994年 | 31篇 |
1993年 | 27篇 |
1992年 | 27篇 |
1991年 | 17篇 |
1990年 | 10篇 |
1989年 | 20篇 |
1988年 | 14篇 |
1987年 | 12篇 |
1986年 | 9篇 |
1985年 | 11篇 |
1984年 | 10篇 |
1983年 | 9篇 |
1982年 | 10篇 |
1981年 | 5篇 |
1980年 | 11篇 |
1979年 | 10篇 |
1978年 | 7篇 |
1977年 | 4篇 |
1976年 | 11篇 |
1975年 | 4篇 |
1973年 | 6篇 |
排序方式: 共有1241条查询结果,搜索用时 78 毫秒
991.
We consider an event‐triggered update scheme for the problem of multiagent consensus in the presence of faulty and malicious agents within the network. In particular, we focus on the case where the agents take integer (or quantized) values. To keep the regular agents from being affected by the behavior of faulty agents, algorithms of the mean subsequence reduced type are employed, where neighbors taking extreme values are ignored in the updates. Different from the real‐valued case, the quantized version requires the update rule to be randomized. We characterize the error bound on the achievable level of consensus among the agents as well as the necessary structure for the network in terms of the notion of robust graphs. We verify via a numerical example the effectiveness of the proposed algorithms. 相似文献
992.
Chemical vapour deposition of corrosion-resistant TiN film to the inner walls of long steel tubes 总被引:1,自引:0,他引:1
A uniform TiN film was coated on to the inner walls of long steel tubes by moving a chemical vapour deposition furnace along the tubes. The moving direction of the furnace from outlet side to inlet side gave a more homogeneous coating than the reverse moving direction. The TiN-coated steel tube (inside diameter 10 mm) was obtained under the following conditions; peak deposition temperature 1050° C, total flow rate of reactant gas (TiCl4 + N2 + H2) 6.0 ml sec–1, moving velocity of the furnace 2.8 mm min–1. The inner wall of the coated tube showed high corrosion resistance for dipping in 6N HCI aqueous solution for 17 h. 相似文献
993.
Y Nomura H Yagi K Onigata S Yutani T Nagashima R Ogawa K Nagashima A Morikawa 《Canadian Metallurgical Quarterly》1995,37(6):706-709
The unusual case of a Japanese newborn XX male is presented. Examination of chromosomes in amniotic fluid cells had shown a normal female karyotype (46,XX), but ultrasonography revealed a penis and a scrotum. The neonate had normal male external genitalia, and serum levels of luteinizing hormone, follicle stimulating hormone, and testosterone were all within the normal range. High resonance chromosome analysis revealed an excess portion on the short arm of one of the X chromosomes. We examined his genomic DNA by polymerase chain reaction (PCR) and detected two Y specific regions in his genomic DNA, the sex-determining region Y (SRY) and pseudoautosomal boundary Y. Nucleotide sequencing of the PCR products of SRY indicated no mutation. These findings suggested that the translocation or insertion of an SRY region on the X chromosome led to the development of testicles and a male phenotype. 相似文献
994.
Hideaki Oka Seiichi Ishimoto Toshiki Miyamoto Yoshio Harano Tatsuya Imoto 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1975,25(6):411-418
The ammoxidation of propylene on Fe-Bi-P mixed oxide catalyst was studied at 500 °C by the pulse reaction technique, to examine the effects of P(P = 0–4) and P (P/P = 0–3) on the catalyst activity. Since the ammoxidation of propylene proceeds through consumption of oxygen from the catalyst even in the absence of oxygen, the reduction of catalyst progresses with the number of O2-free pulse, losing its activity. In the presence of oxygen, however, the conversion of propylene and the selectivities of acrylonitrile, acetonitrile, CO2, and CO vary with the pulse number, but settle to some steady values corresponding to P/P. It is also found that the conversion and the selectivities depend on the oxidation state of the catalyst, the latter also depending on P/P in the reactants, and that the catalyst working in the flow system may be being reduced to some extent. 相似文献
995.
Reduction of 1,3-butadiene with H2(D2) on a Pt electrode in 0.5 M H2SO4(D2SO4) was studied on open circuit. Results on the reaction kinetics, the open circuit potential, the product distribution and the isotope exchange show that (1) the diffusion of 1,3 butadiene (1,3-C″4) or H2 controls the reaction rate according as PH/PC″4 > 20 or < 20, respectively (called B- or H-region), (2) in B-region, butane (C4) is a main product (90%) and produced via 1-butene (1-C′4), (3) in H-region, C4 (50%) is also produced via 1-C′4 and the rest (50%) is 1-C′4, t- and c-2-C′4 in a ratio of 66:20:14, (4) the isotope exchange occurs by the step C4H6(a) + H(a)?C4H7(a) and C4H8(a) + H(a)?C4H9(a), (5) there are two kinds of C4H7(a); one gives 1-C′4 and t-2-C′4 and the other c-2-C′4 and (6) the paths from 1-C′4 to C4 and from t- and c-2-C′4 to C4 are different; the latter gives a more enhanced isotope exchange. 相似文献
996.
Yamakoshi Ken-Ichi Shimazu Hideaki Togawa Tatsuo Fukuoka Masakazu Ito Hiroshi 《IEEE transactions on bio-medical engineering》1980,(3):156-161
A new method for the noninvaive measurement of hematocrit by means of electrical admittance plethysmography was developed. The pninciple of this method is based on the evidence that the elecical admittance variation in a finger segment inmersed in an electrolyte solution disappears when the resistivity of the solution is equal to that of the blood flowing into the segment. Thus, the blood resistivity and, therefore, the hematocrit can be noninvasively determined from the electrolyte resistivity. The hematocrit values determined by this method (HctY) were compared with those by the capillary method (Hctc) in 16 subjects: the linear regression equation was HctY = 1.02Hctc-0.35 with a correlation coefficient r = 0.981. 相似文献
997.
Hideaki Ohashi Mayumi Tsuji Tatsunori Oguchi Yutaro Momma Tetsuhito Nohara Naohito Ito Ken Yamamoto Miki Nagata Atsushi Michael Kimura Yuji Kiuchi Kenjiro Ono 《International journal of molecular sciences》2022,23(17)
Alzheimer’s disease (AD) is a neurodegenerative disease that leads to progressive cognitive decline. Several effective natural components have been identified for the treatment of AD. However, it is difficult to obtain conclusive evidence on the safety and effectiveness of natural components, because a variety of factors are associated with the progression of AD pathology. We hypothesized that a therapeutic effect could be achieved by combining multiple ingredients with different efficacies. The purpose of this study was thus to evaluate a combination treatment of curcumin (Cur) and ferulic acid (FA) for amyloid-β (Aβ)-induced neuronal cytotoxicity. The effect of Cur or FA on Aβ aggregation using thioflavin T assay was confirmed to be inhibited in a concentration-dependent manner by Cur single or Cur + FA combination treatment. The effects of Cur + FA on the cytotoxicity of human neuroblastoma (SH-SY5Y) cells induced by Aβ exposure were an increase in cell viability, a decrease in ROS and mitochondrial ROS, and repair of membrane damage. Combination treatment showed an overall higher protective effect than treatment with Cur or FA alone. These results suggest that the combined action mechanisms of Cur and FA may be effective in preventing and suppressing the progression of AD. 相似文献
998.
Autism spectrum disorders (ASD) and attention-deficit/hyperactivity disorder (ADHD) are two debilitating neurodevelopmental disorders. The former is associated with social impairments whereas the latter is associated with inattentiveness, hyperactivity, and impulsivity. There is recent evidence that both disorders are somehow related and that genes may play a large role in these disorders. Despite mounting human and animal research, the neurological pathways underlying ASD and ADHD are still not well understood. Scientists investigate neurodevelopmental disorders by using animal models that have high similarities in genetics and behaviours with humans. Mice have been utilized in neuroscience research as an excellent animal model for a long time; however, the zebrafish has attracted much attention recently, with an increasingly large number of studies using this model. In this review, we first discuss ASD and ADHD aetiology from a general point of view to their characteristics and treatments. We also compare mice and zebrafish for their similarities and discuss their advantages and limitations in neuroscience. Finally, we summarize the most recent and existing research on zebrafish and mouse models of ASD and ADHD. We believe that this review will serve as a unique document providing interesting information to date about these models, thus facilitating research on ASD and ADHD. 相似文献
999.
Yutaro Kondo Susumu Suzuki Shoya Ono Mitsuo Goto Satoru Miyabe Tetsuya Ogawa Hiromi Tsuchida Hideaki Ito Taishi Takahara Akira Satou Toyonori Tsuzuki Kazuhiro Yoshikawa Ryuzo Ueda Toru Nagao 《International journal of molecular sciences》2022,23(8)
The expression of programmed death ligand-1 (PD-L1) is controlled by complex mechanisms. The elucidation of the molecular mechanisms of PD-L1 expression is important for the exploration of new insights into PD-1 blockade therapy. Detailed mechanisms of the in situ expression of PD-L1 in tissues of oral squamous cell carcinomas (OSCCs) have not yet been clarified. We examined the mechanisms of PD-L1 expression focusing on the phosphorylation of downstream molecules of epidermal growth factor (EGF) and interferon gamma (IFN-γ) signaling in vitro and in vivo by immunoblotting and multi-fluorescence immunohistochemistry (MF-IHC), respectively. The in vitro experiments demonstrated that PD-L1 expression in OSCC cell lines is upregulated by EGF via the EGF receptor (EGFR)/PI3K/AKT pathway, the EGFR/STAT1 pathway, and the EGFR/MEK/ERK pathway, and by IFN-γ via the JAK2/STAT1 pathway. MF-IHC demonstrated that STAT1 and EGFR phosphorylation was frequently shown in PD-L1-positive cases and STAT1 phosphorylation was correlated with lymphocyte infiltration and EGFR phosphorylation. Moreover, the phosphorylation pattern of the related molecules in PD-L1-positive cells differed among the cases investigated. These findings indicate that PD-L1 expression mechanisms differ depending on the tissue environment and suggest that the examination of the tissue environment and molecular alterations of cancer cells affecting PD-L1 expression make it necessary for each patient to choose the appropriate combination drugs for PD-1 blockade cancer treatment. 相似文献
1000.