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   655篇
  免费   17篇
电工技术   3篇
综合类   1篇
化学工业   139篇
金属工艺   9篇
机械仪表   13篇
建筑科学   25篇
能源动力   15篇
轻工业   79篇
水利工程   2篇
无线电   33篇
一般工业技术   103篇
冶金工业   174篇
原子能技术   1篇
自动化技术   75篇
  2023年   7篇
  2022年   27篇
  2021年   37篇
  2020年   16篇
  2019年   16篇
  2018年   16篇
  2017年   14篇
  2016年   16篇
  2015年   15篇
  2014年   17篇
  2013年   23篇
  2012年   29篇
  2011年   40篇
  2010年   25篇
  2009年   20篇
  2008年   20篇
  2007年   20篇
  2006年   24篇
  2005年   16篇
  2004年   23篇
  2003年   11篇
  2002年   11篇
  2001年   10篇
  2000年   11篇
  1999年   15篇
  1998年   50篇
  1997年   25篇
  1996年   26篇
  1995年   8篇
  1994年   12篇
  1993年   11篇
  1992年   1篇
  1991年   6篇
  1990年   5篇
  1989年   5篇
  1988年   5篇
  1987年   5篇
  1986年   6篇
  1985年   3篇
  1984年   2篇
  1982年   1篇
  1981年   4篇
  1980年   5篇
  1979年   1篇
  1978年   1篇
  1977年   2篇
  1976年   6篇
  1974年   1篇
  1973年   1篇
  1972年   1篇
排序方式: 共有672条查询结果,搜索用时 15 毫秒
591.
The model-building laboratory, more than just a place for building models, is a place of study, research, thought processes, and ideation; the place where the acquisition and transmission of knowledge constitutes a fundamental method for growth both for the students as well as the instructors; the place where disciplines are not always considered akin can meet and be compared. Architecture and mathematics come together in this exhibit for Nexus 2000 at the Museum of Architecture (MusArc) in Ferrara, Italy.  相似文献   
592.
Samples of two potato cultivars (Agria and Merit), cultivated either conventionally or organically, were analysed to evaluate their suitability to transformation into powder. Agria cultivar potatoes from the conventional farming were selected as the most suitable for drying process both for their high-dry matter and good nutritional value. Blanching resulted in the most effective treatment to prevent potato browning. The potato powder was obtained by means of a drum dryer using different process parameters (temperature, time and product thickness) to minimise thermal damage on the final product. The effects of these different processes were evaluated by analysing some quality indicators, as final moisture, nutrients (carbohydrates, proteins and amino acids) and colour of the powder, and rheological properties of the rehydrated puree. The results of such analyses showed that the lower the process temperature, the better the powder quality.  相似文献   
593.
Uncoupling proteins (UCPs) form a distinct subfamily of the mitochondrial carrier family (MCF) SLC25. Four UCPs, DmUCP4A-C and DmUCP5, have been identified in Drosophila melanogaster on the basis of their sequence homology with mammalian UCP4 and UCP5. In a Parkinson’s disease model, DmUCP4A showed a protective role against mitochondrial dysfunction, by increasing mitochondrial membrane potential and ATP synthesis. To date, DmUCP4A is still an orphan of a biochemical function, although its possible involvement in mitochondrial uncoupling has been ruled out. Here, we show that DmUCP4A expressed in bacteria and reconstituted in phospholipid vesicles catalyzes a unidirectional transport of aspartate, which is saturable and inhibited by mercurials and other mitochondrial carrier inhibitors to various degrees. Swelling experiments carried out in yeast mitochondria have demonstrated that the unidirectional transport of aspartate catalyzed by DmUCP4 is not proton-coupled. The biochemical function of DmUCP4A has been further confirmed in a yeast cell model, in which growth has required an efflux of aspartate from mitochondria. Notably, DmUCP4A is the first UCP4 homolog from any species to be biochemically characterized. In Drosophila melanogaster, DmUCP4A could be involved in the transport of aspartate from mitochondria to the cytosol, in which it could be used for protein and nucleotide synthesis, as well as in the biosynthesis of ß-alanine and N-acetylaspartate, which play key roles in signal transmission in the central nervous system.  相似文献   
594.
We present experiments on macroscopic quantum effects in Josephson junctions with different relevant junction parameters at a temperature well above the classical-quantum crossover temperature. This has been possible by extending the measurements on the escape rate out of the metastable state at higher sweeping frequency (dI/dt up to 100 A/sec.) in order to induce non-stationary conditions in the energy potential describing the junction dynamics. The non-stationary regime for the system allows a direct observation of energy level quantitation when the rate of change of the external energy, measured in terms of the level spacing, is fast with respect to the thermal transitions between levels.  相似文献   
595.
A prospective study was carried out to determine the effectiveness and tolerance of the combination of 5-fluorouracil (600 mg/m2) and Adriamycin (50 mg/m2) given iv every 3 weeks to patients with disseminated transitional cell carcinoma of the urinary tract. Twenty-one of 23 patients entered in the study were evaluable for both response and toxicity. Two patients had complete responses and six had partial responses (greater than or equal to 50% reduction), yielding an overall response rate (complete plus partial) of 38%. Leukopenia (72.7%) and thrombocytopenia (54.5%) were common. Toxicity was life-threatening in one patient. Other common side effects were alopecia, nausea and vomiting, and a generalized feeling of weakness. Responders had a median survival time of 29 weeks compared to a median survival time of 9 weeks for nonresponders.  相似文献   
596.
A quantitative microscopy method for measuring the mesophase content in pitch has been developed because conventional solubility methods often do not reflect mesophase contents accurately. The general technique utilizes area measurements on photomicrographs of polished specimens to determine volume percent mesophase. Slight modifications to the general method are necessary to overcome unique problems associated with measurements on low (0–15%), intermediate (15–70%) and high (70–100%) mesophase content pitches. Typical data are presented for samples from each regime. The limitations of the method are discussed.  相似文献   
597.
598.
IL-12 has been shown to be involved in the pathogenesis of Th1-mediated autoimmune diseases, but its role in antibody-mediated autoimmune pathologies is still unclear. We investigated the effects of exogenous and endogenous IL-12 in experimental autoimmune myasthenia gravis (EAMG). EAMG is an animal model for myasthenia gravis, a T cell-dependent, autoantibody-mediated disorder of neuromuscular transmission caused by antibodies to the muscle nicotinic acetylcholine receptor (AChR). Administration of IL-12 with Torpedo AChR (ToAChR) to C57BL/6 (B6) mice resulted in increased ToAChR-specific IFN-gamma production and increased anti-ToAChR IgG2a serum antibodies compared with B6 mice primed with ToAChR alone. These changes were associated with earlier and greater neurophysiological evidence of EAMG in the IL-12-treated mice, and reduced numbers of AChR. By contrast, when IL-12-deficient mice were immunized with ToAChR, ToAChR-specific Th1 cells and anti-ToAChR IgG2a serum antibodies were reduced compared to ToAChR-primed normal B6 mice, and the IL-12-deficient mice showed almost no neurophysiological evidence of EAMG and less reduction in AChR. These results indicate an important role of IL-12 in the induction of an antibody-mediated autoimmune disease, suggest that Th1-dependent complement-fixing IgG2a anti-AChR antibodies are involved in the pathogenesis of EAMG, and help to account for the lack of correlation between anti-AChR levels and clinical disease seen in many earlier studies.  相似文献   
599.
Long-term follow-up studies of patients with suspected viral myocarditis reveal progression to dilated cardiomyopathy (DCM) in a significant number of cases. Thus, an underlying viral etiology has been hypothesized in the pathogenesis of ongoing heart disease that leads to DCM. Recent application of molecular biology in clinical diagnosis has strengthened this hypothesis. By use of probe hybridization and polymerase chain reaction, enteroviral RNA has been detected in the myocardium of patients at all stages of the disease process: myocarditis, chronic heart disease, and DCM. Experimental murine models of enterovirus-induced heart disease provide a framework for examining the pathogenic mechanisms. Viral cytotoxicity, immunological responses, viral RNA persistence, and spasm of the coronary microvasculature are all implicated in the ongoing disease process. Abnormal cardiac function and heart failure are attributed to the pathological changes that occur.  相似文献   
600.
A series of mutants of human IL-1 receptor antagonist (IL-1ra) has been designed by comparison of IL-1ra and IL-1beta structures in order to increase receptor antagonist capacity. Upon in vitro and in vivo assay of IL-1 antagonism, the IL-1ra mutants DoB 0039 (N91-->R), DoB 0040 (T109-->A) and DoB 0041 (N91/T109-->R/A) could inhibit IL-1beta effects more efficiently than wild-type IL-1ra, with DoB 0041 being the most active. Analysis of the receptor-binding capacity of the IL-1ra mutants showed that all three mutants could inhibit binding of IL-1alpha or IL-1beta to IL-1RI-bearing cells more efficiently than wild-type IL-1ra. Conversely, binding of IL-1beta to IL-1RII-bearing cells could be inhibited by DoB 0041 much less efficiently than by wild-type IL-1ra. It is known that the two types of IL-1 receptors (IL-1RI and IL-1RII) play different roles in the regulation of IL-1 activity, with IL-1RI being solely responsible for cell triggering upon IL-1 binding, whereas IL-1RII acts as a scavenger of IL-1 and can thus be considered as a natural IL-1 inhibitor. Thus, the enhanced inhibitory capacity of DoB 0041 as compared with wild-type IL-1ra is explained in terms of better binding to the activating receptor IL-1RI and poorer interaction with the inhibitory receptor IL-1RII.  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