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   3588篇
  免费   6篇
电工技术   1篇
综合类   2篇
化学工业   56篇
金属工艺   1篇
机械仪表   3篇
建筑科学   19篇
矿业工程   3篇
能源动力   3篇
轻工业   18篇
水利工程   1篇
无线电   21篇
一般工业技术   23篇
冶金工业   3415篇
原子能技术   2篇
自动化技术   26篇
  2021年   2篇
  2020年   4篇
  2018年   5篇
  2017年   7篇
  2016年   2篇
  2015年   4篇
  2014年   7篇
  2013年   17篇
  2012年   2篇
  2011年   7篇
  2010年   6篇
  2009年   4篇
  2008年   7篇
  2007年   6篇
  2006年   9篇
  2005年   13篇
  2004年   5篇
  2003年   11篇
  2002年   5篇
  2001年   1篇
  2000年   3篇
  1999年   105篇
  1998年   1010篇
  1997年   607篇
  1996年   381篇
  1995年   247篇
  1994年   182篇
  1993年   219篇
  1992年   39篇
  1991年   64篇
  1990年   56篇
  1989年   66篇
  1988年   60篇
  1987年   46篇
  1986年   35篇
  1985年   35篇
  1984年   1篇
  1983年   8篇
  1982年   21篇
  1981年   16篇
  1980年   19篇
  1979年   3篇
  1978年   5篇
  1977年   97篇
  1976年   131篇
  1975年   8篇
  1973年   1篇
  1968年   1篇
  1955年   1篇
  1927年   1篇
排序方式: 共有3594条查询结果,搜索用时 0 毫秒
21.
The cover image, by Bruna A. Bregadiolli et al., is based on the Research Article Towards the synthesis of poly(azafulleroid)s: main chain fullerene oligomers for organic photovoltaic devices, DOI: 10.1002/pi.5419 .

  相似文献   

22.
Chemically vapor deposited Al2O3 coatings, due to their high hardness and chemical inertness, are currently the state of art in the cutting tool industry. The conventional high deposition temperature of about 1050 °C for Al2O3 coatings, based on the water–gas shift process, has to a great extend restricted the development of several hybrid coatings, such as TiC/TiN/TiCN/Al2O3. To overcome this limitation, alternate systems to deposit Al2O3 at moderate temperatures have been investigated. Systems using NO–H2, H2O2, NO2–H2 and HCOOH were identified and thermodynamic calculations were performed to evaluate them as potential sources of oxygen donors to form Al2O3 in the moderate temperature range of 700–950 °C. Preliminary results have clearly demonstrated that it is possible to grow moderate temperature alumina (using such alternate sources) on the TiC/TiN coated cemented carbide substrates.  相似文献   
23.
Dynamic insulation, a form of ‘Breathing Wall’ construction which allows the movement of air and moisture through the external walls of a building, was seen as one possible method for reducing building envelope heat losses and achieving high indoor air quality. A research investigation was conducted to provide a firm scientific understanding of dynamic insulation. An important outcome of the work will be the development of building envelope designs which effectively and economically employ dynamic insulation in cold climates. This paper presents some general conclusions, confirming that the energy saving produced by dynamic insulation alone is small relative to that obtained in conjunction with conventional air heat recovery methods.  相似文献   
24.
Zinc has an important place amongst inhibitors of crystallisation and crystal growth. These views are supported by in vivo and in vitro studies which suggest that the urinary zinc level is a significant factor in urolithiasis. Some recent studies have given contradictory results. Blood serum and urinary zinc levels were measured in 30 normal healthy controls and 42 stone forming patients (renal, ureteric and vesical). Statistically significant levels were found in all groups, varying according to the number of calculi. Increased urinary zinc levels and decreased serum zinc levels appear to be secondary to the process of stone formation. The role of zinc as an inhibitor of urolithiasis is questionable.  相似文献   
25.
26.
27.
OBJECTIVE: We followed a group of 85 Finnish asbestosis patients radiographically for an average of 6.5 (range 2-10) years to examine the progression of the disease and to assess possible explanations for the progression. METHODS: The examinations included full-size chest radiographs and a blood specimen analysis. The radiographs were classified according to the 1980 International Labor Office (ILO) classification. Progression was accepted if the second or third radiography was estimated (in a side-by-side comparison) to have more profusion of small opacities qualitatively than the first, even if the radiographs were classified into the same profusion category. RESULTS: In all, 38% of the patients showed progression during the follow-up period. The average progression of small opacities ranged from ILO 1/1 to ILO 2/2 (0.4 minor ILO categories/year). The asbestosis was progressive more often among the sprayers than among the insulators and asbestos factory workers [cross-tabulation, odds ratio (OR) 5.0, 95% confidence interval (95% CI) 1.2-20]. In the logistic regression model the ILO classification category at the beginning of the follow-up (OR 1.54; 95% CI 0.96-2.47), the fibronectin (OR 1.01; 95% CI 1.00-1.01) and angiotensin-converting enzyme (ACE; OR 1.10; 95% CI 1.00-1.20) levels, and the erythrocyte sedimentation rate (ESR; OR 1.05; 95% CI 1.00-1.10) were statistically associated with the radiographic progression of small opacities. Abnormalities of the pleura were found to progress more often among the patients with progressive parenchymal opacities. CONCLUSION: For the progression of small-opacity profusion the significant predictors in the logistic regression model were the ILO profusion category at the beginning of the follow-up period, the fibronectin level, the ACE value, and the ESR. The model correctly classified 94% of the patients with progression and 65% of those without progression. The differences in the mean values recorded for the biomarkers between the progressors and nonprogressors, however, were small and may therefore not be of any importance to the clinician.  相似文献   
28.
BACKGROUND: Combined treatment of allograft recipients with anti-CD40 ligand and CTLA-4Ig (costimulation blockade) is a powerful promising albeit not consistently tolerizing therapy. It would be desirable to use an effective conventional immunosuppressive regimen in low doses or for a short course as an adjunct; however, cyclosporine treatment drastically blunts the ability of costimulation blockade to produce long-term engraftment. METHODS: Short courses of cyclosporine or rapamycin were compared as adjuncts to costimulation blockade in the murine BALB/c to C3H/He heterotopic cardiac allograft model. RESULTS: Although cyclosporine therapy blocked the capacity of costimulation blockade to produce permanent engraftment, combined rapamycin and costimulation blockade treatment produced permanent engraftment. CONCLUSION: A theoretical basis for the differing effects of cyclosporine and rapamycin upon the outcome of costimulation blockade is forwarded. Combined use of costimulation blockade and rapamycin may provide a means to bring costimulation blockade into the clinic.  相似文献   
29.
PURPOSE: The CD20 antigen is expressed on more than 90% of B-cell lymphomas. It is appealing for targeted therapy, because it does not shed or modulate. A chimeric monoclonal antibody more effectively mediates host effector functions and is itself less immunogenic than are murine antibodies. PATIENTS AND METHODS: This was a multiinstitutional trial of the chimeric anti-CD20 antibody, IDEC-C2B8. Patients with relapsed low grade or follicular lymphoma received an outpatient treatment course of IDEC-C2B8 375 mg/m2 intravenously weekly for four doses. RESULTS: From 31 centers, 166 patients were entered. Of this intent-to-treat group, 48% responded. With a median follow-up duration of 11.8 months, the projected median time to progression for responders is 13.0 months. Serum antibody levels were sustained longer after the fourth infusion than after the first, and were higher in responders and in patients with lower tumor burden. The majority of adverse events occurred during the first infusion and were grade 1 or 2; fever and chills were the most common events. Only 12% of patients had grade 3 and 3% grade 4 toxicities. A human antichimeric antibody was detected in only one patient. CONCLUSION: The response rate of 48% with IDEC-C2B8 is comparable to results with single-agent cytotoxic chemotherapy. Toxicity was mild. Attention needs to be paid to the rate of antibody infusion, with titration according to toxicity. Further investigation of this agent is warranted, including its use in conjunction with standard chemotherapy.  相似文献   
30.
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