首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   356篇
  免费   6篇
  国内免费   1篇
电工技术   23篇
化学工业   82篇
金属工艺   23篇
机械仪表   12篇
建筑科学   5篇
能源动力   5篇
轻工业   16篇
水利工程   1篇
无线电   47篇
一般工业技术   44篇
冶金工业   65篇
原子能技术   16篇
自动化技术   24篇
  2022年   3篇
  2021年   3篇
  2020年   2篇
  2019年   5篇
  2018年   3篇
  2017年   2篇
  2016年   4篇
  2015年   3篇
  2014年   3篇
  2013年   7篇
  2012年   3篇
  2011年   6篇
  2010年   13篇
  2009年   31篇
  2008年   14篇
  2007年   16篇
  2006年   13篇
  2005年   17篇
  2004年   12篇
  2003年   9篇
  2002年   10篇
  2001年   7篇
  2000年   4篇
  1999年   3篇
  1998年   24篇
  1997年   11篇
  1996年   14篇
  1995年   11篇
  1994年   5篇
  1993年   8篇
  1991年   6篇
  1990年   3篇
  1989年   2篇
  1988年   6篇
  1987年   4篇
  1986年   4篇
  1985年   5篇
  1984年   12篇
  1983年   5篇
  1982年   7篇
  1981年   7篇
  1980年   4篇
  1979年   8篇
  1978年   3篇
  1977年   2篇
  1976年   5篇
  1975年   3篇
  1974年   2篇
  1973年   3篇
  1971年   2篇
排序方式: 共有363条查询结果,搜索用时 15 毫秒
321.
This paper develops an optimal shut-down logic for a protective system which is composed of: 1) a sensing section, 2) a judging section, and 3) a driving section. Each section has two kinds of failures: fail-dangerous and fail-safe. A shut-down logic which minimizes an s-expected loss caused by failures of the protective system is obtained as a simple switching function. A path-set expression of the logic is shown. An example for a glass-lined reactor illustrates that the optimal logic consists of 7 majority rules; 3 of them belong to a stand-alone part and the remaining 4 to a cross-reference part.  相似文献   
322.
The blood compatibility of cellulosic polyelectrolyte complexes (PECs) and the effect of excess charge in PEC on the blood compatibility were examined in detail by both in vivo and in vitro blood tests. For this purpose, two types of quaternary ammonium cellulose derivatives were prepared by treating cellulose or hydroxyethyl cellulose with glycidyl trimethylammonium chloride. In vivo blood tests were made by implanting the polymer-coated suture into a jugular and femoral vein of a dog. In vitro blood tests include the measurement of whole blood coagulation time on polymer-coated glass tubes, platelet adhesion measurements using a column packed with polymer-coated glass beads, and a measurement of activation of the intrinsic coagulation system. It was found that among the PECs examined, the PECs containing quaternary ammonium derivatives as polycation components have an excellent blood compatibility. The experiments on the effect of excess charge in PEC revealed that (i) the relative coagulation time of whole blood is almost independent of the mole ratio of polycation to polyanion component within the mole ratios examined, being in good agreement with those by in vivo blood tests, but (ii) platelet adhesion increases with increasing the mole ratio of polycation/polyanion in the PEC, and (iii) the activation of the intrinsic coagulation system increases with decreasing the mole ratio.  相似文献   
323.
We report herein the extremely unusual case of a 39-year-old woman in whom a giant cavernous hemangioma caused hemobilia. Cavernous hemangioma is the most common benign neoplasm of the liver and rarely causes any clinical symptoms or signs, while hemobilia usually occurs secondary to accidental operative or iatrogenic trauma, vascular disease, inflammatory disorders, gallstones, or tumors of the liver. Although invasive or malignant hepatic tumors often result in a communication between the biliary tract and the blood vessels, only one case of hemobilia caused by a benign cavernous hemangioma has ever been reported, but with no details about the patient. Our patient presented to a local hospital with severe melena as the initial main symptom, where ligation of the right hepatic artery was performed. This failed to relieve her symptoms, and she was subsequently referred to our department where a right hepatectomy was performed. Histopathological examination revealed no malignancy combined with the tumor; however, the hemangioma was exposed to the bile duct in segment VIII, which was presumably the cause of the hemobilia. This patient remains in good health almost 6 years after her operation. To the best of our knowledge this is the first case report of hemobilia caused by a cavernous hemangioma, and is accompanied by a detailed analysis.  相似文献   
324.
Confocal scanning microscopy was used to study protein uptake to porous adsorbents during batch experiments in a finite bath. By coupling of a fluorescent dye to the protein molecules the penetration of single adsorbent particles at different times during batch uptake could be observed visually. Intensity profiles of the protein distribution within a single particle were obtained by horizontal scanning. After integration of the profiles the overall fluorescence within a bead could be calculated. Relating the overall fluorescence at different incubation times to the value at equilibrium allowed the construction of the fractional approach to equilibrium versus time. These data were compared to uptake curves, which had been obtained by measurements of the protein concentration in the supernatant and an excellent agreement of the curves was detected. The procedure was performed for two different proteins (lysozyme and human IgG) on two different media for protein adsorption (SP Sepharose Fast Flow and SP Sepharose XL; Pharmacia Biotech) and in all cases it could be shown, that the results from the direct measurements by confocal microscopy correspond very well to the data obtained from the indirect measurements in the fluid phase.  相似文献   
325.
326.
The birefringence for uniaxially extended DCP-cured natural rubber was measured in the temperature range of 213K–353K. The variation of birefringence reflected the changes of the network structure, i.e. the development and disappearence of strain-induced crystals, and the degree of the orientation of amorphous network chains. It became clear from the variation of birefringence that the nucleation condition which is required to allow growth of an extended chain crystal occurred at extension ratio of 2.5–3.5.  相似文献   
327.
In this paper, we derive a fast recurrence relation for a computer-generated-hologram (CGH). The recurrence relation based on Taylor expansion reduces the number of cosine computations as compared with conventional CGH formula. The recurrence relation calculates a CGH 7 or 8 times faster than the conventional CGH formula on a CPU and graphics processing unit (GPU). In addition, there is almost no difference between a CGH generated by the recurrence relation and that generated by the conventional type.  相似文献   
328.
Most Alzheimer disease patients show deposition of amyloid β (Aβ) peptide in blood vessels as well as the brain parenchyma. We previously found that vascular endothelial cells express amyloid β precursor protein (APP) 770, a different APP isoform from neuronal APP695, and that they produce amyloid β peptide. We analyzed the glycosylation of APP770 and found that O-glycosylated sAPP770 is preferentially processed by proteases for Aβ production. Because the soluble APP cleavage product sAPP is considered to be a possible marker for Alzheimer disease diagnosis, sAPP, consisting of a mixture of these variants, has been widely measured. We hypothesized that measurement of the endothelial APP770 cleavage product in patients separately from that of neuronal APP695 would enable us to discriminate between endothelial and neurological dysfunctions. Our recent findings, showing that the level of plasma sAPP770 is significantly higher in patients with acute coronary syndrome, raise the possibility that sAPP770 could be an indicator of endothelial dysfunction. In this review, we first describe the expression, glycosylation, and processing of APP770, and then discuss sAPP770 as a novel biomarker candidate of acute coronary syndrome.  相似文献   
329.
Abstract— Wide‐view (WV) films for TN‐mode LCDs, which optimize the optical parameters of the polymerized discotic material (PDM) layer and cellulose triacetate (CTA) have been developed. The development concept of the WV film and realization of its concept in the past and for the future will be reviewed. In particular, the discotic molecular alignment control enabled the improvement of the contrast ratio at oblique viewing angles of TN‐mode LCDs. In addition, color shifts at oblique angles are important for large‐screen TN‐mode LCD monitors and LCD‐TV sets. To improve the color‐shift problem, new technologies have been developed.  相似文献   
330.
Summary The membrane performance of the polycondensates derived from 2,5-pyridinedicarboxylic acid chloride and malonyl dihydrazide was studied in reverse osmosis. It depended on drying time, and the kind and amount of a cross-linking agent and an inorganic additive. The membrane strength generally exceeded that of a cellulose acetate membrane. The rejection difference between transition and alkali metal salts was discussed in terms of complexation and the molecular size of the additive. A potential application was suggested for the separation between the two metals through the membrane of a large rejection difference.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号