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   112篇
  免费   3篇
电工技术   1篇
综合类   2篇
化学工业   7篇
金属工艺   2篇
机械仪表   1篇
建筑科学   10篇
轻工业   7篇
水利工程   1篇
无线电   34篇
一般工业技术   14篇
冶金工业   29篇
原子能技术   1篇
自动化技术   6篇
  2020年   1篇
  2019年   1篇
  2017年   2篇
  2015年   2篇
  2013年   5篇
  2011年   5篇
  2010年   3篇
  2009年   5篇
  2008年   4篇
  2007年   7篇
  2006年   4篇
  2005年   7篇
  2004年   5篇
  2003年   2篇
  2002年   4篇
  2001年   2篇
  1999年   4篇
  1998年   11篇
  1997年   12篇
  1996年   4篇
  1994年   4篇
  1992年   1篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1986年   3篇
  1984年   2篇
  1983年   1篇
  1982年   3篇
  1981年   1篇
  1980年   1篇
  1979年   3篇
  1978年   1篇
  1977年   1篇
  1976年   1篇
排序方式: 共有115条查询结果,搜索用时 500 毫秒
61.
BACKGROUND: Non-small cell lung cancer with intrapulmonary metastasis (PM) was recently reclassified according to the revision of the TNM classification. To determine whether the new staging system is appropriate, we analyzed the postoperative prognosis of patients with synchronously detected and resected PM lesions. METHODS: Of 509 patients with non-small cell lung cancer who underwent surgical resection, 42 patients were revealed to have synchronous and ipsilateral PM. Their survival was compared with that of matched stage groups (without PM) by Kaplan-Meier test and log rank test. RESULTS: Two patients who were classified as stage I survived 40 and 30 months after operation, respectively. One patient was determined to be stage II, and survived 100 months postoperatively. Thirty-eight patients were classified as stage IIIA/IIIB (19 each) (90.5% of all cases with PM). There was no significant difference between 3- and 5-year survival rates of the PM stage IIIA group (34.2% and 34.2%) and those of the other IIIA (144 patients; 37.9% and 31.6%). Survival rates of such stage IIIA subgroups as PM, T3 and N2, were comparable. No significant differences were observed between the 3- and 5-year survival rates of the PM stage IIIB (16.6/16.6%) and those of the other stage IIIB (45 cases; 11.7% and 0.0%). The survival rates of such stage IIIB subgroups as PM, T4 and N3 were also similar. CONCLUSIONS: The new staging system for patients with synchronous resectable PM appears to be reasonable regarding survival. Most cases of PM are categorized as locally advanced disease; however, stage IIIA/IIIB cases have become a more heterogeneous population.  相似文献   
62.
A multilayer (sputtered-sliced) Fresnel zone plate (FZP) is one of the promising focusing optics with high spatial resolution for the high-energy X-ray region. This is because a large “aspect ratio” can be realized easily. In addition, it is important that the kinoform FZP (theoretical diffraction efficiency=100%) can be fabricated by the sputtered-sliced method. This paper presents the experimental results of two new approaches for fabrication of a multilayer FZP for X-rays. (1) To achieve higher diffraction efficiency, a multilevel-type (4-step: quasi-kinoform type) FZP was fabricated. This FZP was composed of concentric multilayers of alternating high-Z, low-Z, and composite materials. The composite material layer was deposited by co-sputtering of high-Z and low-Z materials. (2) To achieve smoother zones (multilayer interfaces) at the conventional-type FZP, each target of a sputtering apparatus with two DC-sputtering guns was surrounded by a cover with an aperture, and Ar gas was supplied inside the cover, which led to the deposition at lower Ar gas pressure. As a result, for the former, the efficiency was improved markedly as compared with conventional FZP, and for the latter, the zone roughness was reduced, which has resulted in the improvement of the spatial resolution of the FZP.  相似文献   
63.
A rigorous and simple method of analyzing scattering and absorbing characteristics of multilayered gratings embedded in a dielectric slab has been proposed. The method combines a generalized scattering matrix with a lattice sums matrix and a T-matrix of an isolated single cylinder instead of the aggregate T-matrix. The validity of the present method has been confirmed by several numerical experiments and comparisons with other published results. Numerical examples show that the absorbing characteristics become very complex and are not linear with the decreasing of cylinders’ conductivity, when the arrays are stacked to a multilayered structure and are embedded in a dielectric slab.  相似文献   
64.
Tumor-reactive T cells, known as tumor-infiltrating lymphocyte(TIL)s are known to infiltrate various tumors. Although TILs exert cytotoxic activities against tumor cells, only a small percentage of tumors usually contain TILs that specifically react to tumor antigens. Because the exact role of these lymphocytes is unclear, we investigated the mechanisms of migration and adhesion of TILs to bone metastatic tumors, particularly to osteoblasts and bone marrow-derived stromal cell(BMSC)s. Histopathological examination showed that most TILs in secondary bone metastatic tumors (from primary tumors in the lung or breast) were found in the supporting tissue stroma between the bone and tumor mass. Cultured TILs (obtained from breast tumors) adhered spontaneously to osteoblasts and BMSCs (obtained from patients with osteoarthritis) without exogenous stimulation. Adhesion was further enhanced by chemokines macrophage inflammatory protein (MIP)-1alpha and MIP-1beta. TILs highly expressed activation antigens CD25 and CD69. A spontaneous activation of an integrin, lymphocyte function-associated antigen-1 (LFA-1), was also detected on TILs. TILs produced high concentrations of MIP-1alpha and MIP-1beta and spontaneous polymerization of cytoskeletal F-actin was observed in these cells. Adhesion of TILs to osteoblasts and BMSCs via LFA-1 and very late antigen-4 was associated with the production of osteoclastogen interleukin 6 by the latter cells. Our results indicate that integrins on TILs are activated in an autocrine manner by MIP-1alpha and MIP-1beta, and that treatment with the chemokines increases the binding of TILs on osteoblasts and stromal cells via a mechanism involving intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 as targets for the integrin. Our data also indicated that interactions between TILs and osteoblasts/stromal cells lead to the secretion by the latter of the osteoclastogenic cytokine interleukin 6.  相似文献   
65.
We present a study of 28-year-old Japanese monozygotic female twins with Rett syndrome (RS). To our knowledge, this is the first report of monozygotic twins with RS from Japanese family. There are some differences between twins about seizures, scoliosis and stereotypical hand movements during adolescence. Monozygosity was confirmed by both blood typing and HLA titers.  相似文献   
66.
Polychlorinated biphenyls (PCBs) that are present in transformer oil are a common global problem because of their toxicity and environmental persistence. The development of a rapid, low-cost method for measurement of PCBs in oil has been a matter of priority because of the large number of PCB-contaminated transformers still in service. Although one of the rapid, low-cost methods involves an immunoassay, which uses multilayer column separation, hexane evaporation, dimethyl sulfoxide (DMSO) partitioning, antigen-antibody reaction, and a measurement system, there is a demand for more cost-effective and simpler procedures. In this paper, we report a DMSO partitioning method that utilizes a microfluidic device with microrecesses along the microchannel. In this method, PCBs are extracted and enriched into the DMSO confined in the microrecesses under the oil flow condition. The enrichment factor was estimated to be 2.69, which agreed well with the anticipated value. The half-maximal inhibitory concentration of PCBs in oil was found to be 0.38 mg/kg, which satisfies the much stricter criterion of 0.5 mg/kg in Japan. The developed method can realize the pretreatment of oil without the use of centrifugation for phase separation. Furthermore, the amount of expensive reagents required can be reduced considerably. Therefore, our method can serve as a powerful tool for achieving a simpler, low-cost procedure and an on-site analysis system.  相似文献   
67.
A cellulose model compound, methyl β-D-glucopyranoside (MGP), was subjected to oxygen-alkali treatment in the presence of various kinds of lignin model compounds. Only in the presence of a lignin model compound reactive with oxygen, a significant degradation of MGP was observed and the rate and the extent of its degradation were strongly dependent on the structure and the amount of a lignin model compound. Depression of MGP degradation was found to be achieved by two clearly distinguished mechanisms. One is an enhancement of the degradation of a lignin model compound without the acceleration of MGP degradation and the other is a depression of MGP degradation without significantly deteriorating the degradation of a lignin model compound. An increase in oxygen pressure and a 10% methanol addition belonged to the former case and a change in the ratio of metal ions and a 1% methanol addition belonged to the latter case. The addition of magnesium sometimes resulted in the acceleration of MGP degradation, depending on its ratio to iron.  相似文献   
68.
A small wideband NMOS operational amplifier for high-speed LSIs was fabricated using VLSI technology with a minimum channel width of 3 ?m and minimum gate length of 4.5 ?m. Results such as 0.062 mm2 silicon area, 66 dB DC open-loop gain, 9.6 MHz gain-bandwidth product, +13.8/?19.3 V/?s slew rates and about 200 ns settling time were successfully obtained. The technique to improve transient response is also discussed.  相似文献   
69.
Yasumoto  M. Enomoto  T. 《Electronics letters》1982,18(18):769-771
A fully integrated four-quadrant analogue multiplier based on switched-capacitor technique for realisation of high-speed and high-density analogue LSIs was developed using a MOS VLSI process. Excellent characteristics such as low total harmonic distortion of ?50 dB for two input signals of 1 Vp-p, large dynamic range of 80 dB and fast operation speed of 2 MHz clock rate were obtained. Application to convolvers and correlators is also demonstrated.  相似文献   
70.
Kang M  Chen H  Sato Y  Kamei T  Magara Y 《Water research》2003,37(19):4599-4604
Detection of various types of contaminants in water treatment plant by sophisticated analytical methods such as inductively coupled plasma/mass spectrometry and gas chromatography/mass spectrometry requires hours to days to provide the results. Because naturally occurring ultraviolet (UV) active compounds are commonly present in almost all source waters and can be rapidly monitored by UV absorbance at 260 nm (E260), the extent of correlation between the removal efficiency of E260 and the removal efficiency of As(V) with minimum soluble residual Al by coagulation process was investigated. Percentage removals for E260 were well correlated to those of As(V). When sufficient alum or polyaluminum chloride (PACl) was added for 60-65% removal of E260, 90-95% removal of As(V) was achieved with minimum soluble residual Al regardless of the initial level of turbidity, E260, and As(V). As E260 analysis is precisely available even by an unskilled plant operator in a few minutes, E260 removal efficiency appears to be the promising economical indicator for monitoring the effectiveness of the coagulation process for the removal of contaminants with minimum residual Al.  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