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排序方式: 共有830条查询结果,搜索用时 31 毫秒
51.
A Rajnakova PM Goh ST Chan SS Ngoi A Alponat S Moochhala 《Canadian Metallurgical Quarterly》1997,18(9):1841-1845
The present study investigated the expression and distribution of three isoforms of nitric oxide synthase (NOS) in different anatomical regions of the human stomach and in gastric neoplastic tissues by immunohistochemistry using specific antibodies. Intracellular localization of individual isoenzymes of NOS was detected in normal gastric mucosa. Gastric cancer tissues had a marked reduction of all three NOS isoforms expression. The expression of the endothelial NOS, neuronal NOS and inducible NOS in the tumor tissue was significantly lower than in normal gastric mucosa (P = 0.01, P = 0.02, P < 0.01, respectively). In the tumor tissue the expression of inducible NOS was significantly lower than the expression of both constitutive forms of NOS (P < 0.01). There was a tendency to higher expression of both constitutive forms of NOS in earlier stages T2 of the tumor compared to advanced T4 tumor. In contrast, the expression of inducible NOS was higher than in the advanced T4 tumor than in the earlier stages T2 of the tumor. The mapping of the expression of endothelial NOS, neuronal NOS and inducible NOS in human stomach showed higher expression of NOS isoforms in the distal third than in the proximal third of the stomach (P = 0.03, P = 0.04, P = 0.01, respectively). We conclude that there is greater expression of NOS in the stomach corpus and in antrum than in the proximal third of the normal human stomach mirroring the anatomical predilection of common pathological changes in this part of the human stomach. Furthermore, there was loss of the expression of individual isoenzymes in gastric neoplasms. 相似文献
52.
A conditional decision procedure for high yield processes 总被引:1,自引:0,他引:1
A control chart based on the cumulative count of conforming items between two successive nonconforming ones has been shown to be useful in manufacturing industries, particularly for high-quality processes. However, as the decision is based on a single count value, it is relatively insensitive to process shifts. In this paper a conditional procedure is proposed whereby the sensitivity is improved when the process shift is moderate to large in either direction. In addition, optimal limits are defined in such a way that the average run length becomes maximum when the process average is at the nominal level. The performance of the conditional chart and its optimal limits are investigated and compared with the traditional case. The idea of a conditional procedure is to utilize some of the previous runs when a count value exceeds the limits. This procedure is similar to the supplementary run rules, but the conditional procedure is used when the process is out side of the control limits whereas the supplementary run rules focuses on the in-control situation. The conditional procedure has tighter limits than its original chart. The tighter limits together with the conditionality take care of the process without sacrificing its original in-control probability whilst improving the sensitivity. 相似文献
53.
The response surface methodology (RSM), particularly Box-Behnken design model, was used in this study to obtain the optimum operating conditions for reduction of copper corrosion by-product release using high-dose polyphosphate inhibition. Furthermore, the RSM was also applied to study the main and interactive effects of the parameters investigated. Both analysis of variance (ANOVA) and coefficient of determination (R2) showed that the RSM approach was appropriate for the optimization of high-dose polyphosphate inhibition. The main effects of polyphosphate dosage and pH were found significant in reducing copper release using high-dose polyphosphate whereas the effect of contact time was less significant. In terms of interactions between the effects, the relation between polyphosphate dosage and the pH was the most significant. The optimal polyphosphate dosage, pH and contact time were found to be 22-28 mg/L of polyphosphate as P, 9-10, and 36 h, respectively. The highest total copper release reduction was estimated as 95.86% under the optimum condition. Surface analysis using both SEM-EDX and XRD discovered that cupric phosphate was present on the copper surface treated with high-dose polyphosphate inhibition. This implied that cupric phosphate could be responsible for the reduction of copper release by forming a protective layer. 相似文献
54.
防静电、防过电流和过电压冲击是目前工程师设计电子产品时必须考虑的一个问题,否则这些产品的市场销路一定会大打折扣。本文集中探讨了目前市场上所有的电路保护技术,并展望了未来电路保护器件的发展方向。 相似文献
55.
The fabrication of a dispersion slope equaliser on a silica-based planar lightwave circuit for 16×20 Gbit/s wavelength division multiplexing transmission is reported. This device comprises an array of sixteen equalisers with different compensation values and an arrayed-waveguide grating for wavelength multiplexing 相似文献
56.
Janarthanan Supramaniam Darren Yi Sern Low See Kiat Wong Loh Teng Hern Tan Bey Fen Leo Bey Hing Goh Dazylah Darji Fatimah Rubaizah Mohd Rasdi Kok Gan Chan Learn Han Lee Siah Ying Tang 《International journal of molecular sciences》2021,22(11)
Cellulose nanofibers (CNF) isolated from plant biomass have attracted considerable interests in polymer engineering. The limitations associated with CNF-based nanocomposites are often linked to the time-consuming preparation methods and lack of desired surface functionalities. Herein, we demonstrate the feasibility of preparing a multifunctional CNF-zinc oxide (CNF-ZnO) nanocomposite with dual antibacterial and reinforcing properties via a facile and efficient ultrasound route. We characterized and examined the antibacterial and mechanical reinforcement performances of our ultrasonically induced nanocomposite. Based on our electron microscopy analyses, the ZnO deposited onto the nanofibrous network had a flake-like morphology with particle sizes ranging between 21 to 34 nm. pH levels between 8–10 led to the formation of ultrafine ZnO particles with a uniform size distribution. The resultant CNF-ZnO composite showed improved thermal stability compared to pure CNF. The composite showed potent inhibitory activities against Gram-positive (methicillin-resistant Staphylococcus aureus (MRSA)) and Gram-negative Salmonella typhi (S. typhi) bacteria. A CNF-ZnO-reinforced natural rubber (NR/CNF-ZnO) composite film, which was produced via latex mixing and casting methods, exhibited up to 42% improvement in tensile strength compared with the neat NR. The findings of this study suggest that ultrasonically-synthesized palm CNF-ZnO nanocomposites could find potential applications in the biomedical field and in the development of high strength rubber composites. 相似文献
57.
Teo M. Mhaisalkar S.G. Wong E.H. Poi-Siong Teo Wong C.C. Kristine Ong Chin Foo Goh Lay Kuan Teh 《Components and Packaging Technologies, IEEE Transactions on》2005,28(1):157-164
The anisotropic conductive adhesive (ACA) is a promising solder alternative candidate that shows potential for further pitch reduction. Although much work has been published on ACA joint behavior, study on correlation of material properties with reliability performance is still lacking. The main objective in this study was to identify the impact of material properties on reliability, so as to engineer highly reliable microelectronics assemblies. Four representative ACA materials (both film and paste types) with diverse properties were selected. Material properties were characterized as close as possible to "stress test" conditions so as to allow more accurate correlation predictions. Reliability performance was obtained by assembling test chips of 200-/spl mu/m pitch onto BT-substrates, then subjecting them to reliability tests. Correlation analysis was conducted and key material properties that contributed to good reliability performance were identified. Findings indicated that the best properties for high reliability assemblies were: high adhesion strength after subjecting to "stress aging", low coefficient of moisture expansion (CME) and low elastic modulus (E). 相似文献
58.
In this note, a simple computational procedure is given for solving a class of optimization problems, where an objective function is to be minimized subject to conventional inequality constraints as well as to inequality constraints of the functional type. 相似文献
59.
Minor constituents of palm oil 总被引:5,自引:5,他引:0
Crude palm oil contains about 1% of minor components including carotenoids, tocopherols, sterols, triterpene alcohols, phospholipids,
glycolipids and terpenic and paraffinic hydrocarbons. The nutritionally important components such as carotenes and tocopherols
also improve stability of the oil. Although a highly valued product, carotene unfortunately is bleached or destroyed in refining
because suitable recovery technology is not available. Thermal degradation of carotene, previously suspected of giving rise
to undesirable chemicals, now is known to furnish mainly harmless hydrocarbons, most of which are removed by the deodorization
step in refining. Tocopherols, being natural antioxidants, need to be carefully preserved during milling, refining, fractionation
and modification of palm oils. The accumulation of tocopherols in the palm fatty acid distillate promises to provide a new
source for the recovery of this valuable substance. The role played by phospholipids is frequently misunderstood because they
can act in two ways, i.e. as an antioxidant synergist and a surface active agent to disperse impurities in oil. In crude palm
oil the phospholipid content is small, because most of it is removed during milling; the phosphorus content is due mainly
to inorganic phosphorus. Among the sterols, cholesterol constitutes too small a percentage to be of much concern. Sterols,
triterpenoids and terpenoid hydrocarbons are also potentially useful side products should recovery technology become available.
Other newly characterized minor and trace components also are discussed. 相似文献
60.
Chun Hooi Bu Sai Hin Lai Xiang Ting Goh Wen Tong Chong Ren Jie Chin 《Water and Environment Journal》2021,35(1):181-189
Biofilters are promising technologies that widely applied in the treatment of urban stormwater. However, the microbial removal capacity performance depends greatly on the design of biofilters. Hence, this laboratory study attempts to investigate the influence of filter media depths (i.e. 150, 250, 350 and 450 mm) and the variation of native plants, that is, Cow Grass (Axonopus compressus) and Pearl Grass (Axonopus compressus, dwarf) in removing stormwater microorganism particularly Faecal Coliform (FC). Findings showed that a minimum media depth of 300 mm was required to achieve >1 log FC removal. The mean removal of FC at 450 mm depth filter exceeded 2 log for both Cow and Pearl grass biofilter columns. Results showed that there was no statistically significant difference in vegetation type on the performance of FC removal, however, Cow grass biofilter column revealed higher FC mean log removal compared to Pearl grass biofilter column. 相似文献