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   583篇
  免费   24篇
  国内免费   3篇
电工技术   3篇
综合类   5篇
化学工业   153篇
金属工艺   5篇
机械仪表   6篇
建筑科学   27篇
矿业工程   2篇
能源动力   10篇
轻工业   121篇
水利工程   5篇
石油天然气   3篇
无线电   30篇
一般工业技术   85篇
冶金工业   95篇
原子能技术   1篇
自动化技术   59篇
  2023年   7篇
  2022年   10篇
  2021年   16篇
  2020年   6篇
  2019年   11篇
  2018年   10篇
  2017年   15篇
  2016年   14篇
  2015年   9篇
  2014年   16篇
  2013年   26篇
  2012年   25篇
  2011年   45篇
  2010年   20篇
  2009年   16篇
  2008年   31篇
  2007年   29篇
  2006年   20篇
  2005年   22篇
  2004年   18篇
  2003年   17篇
  2002年   11篇
  2000年   10篇
  1999年   11篇
  1998年   15篇
  1997年   15篇
  1996年   9篇
  1995年   9篇
  1994年   7篇
  1993年   8篇
  1992年   10篇
  1990年   10篇
  1989年   3篇
  1988年   4篇
  1986年   7篇
  1985年   9篇
  1984年   4篇
  1982年   4篇
  1981年   11篇
  1980年   7篇
  1979年   8篇
  1978年   3篇
  1977年   7篇
  1976年   3篇
  1975年   6篇
  1974年   3篇
  1973年   9篇
  1972年   3篇
  1971年   5篇
  1912年   2篇
排序方式: 共有610条查询结果,搜索用时 15 毫秒
41.
Porous perovskite (LaMnO3) fibers were prepared by means of wet phase inversion spinning. The influence of different spinning procedures, slurry and coagulation bath composition on fiber shape and pore morphology was studied. The catalytic activity of the prepared fibers was tested for carbon monoxide oxidation as a model reaction in a differential recycle reactor. The results revealed that by suitable choice of process conditions porous catalytically active fibers can be prepared. Catalytic measurements confirmed that the catalytic fibers exhibit an open structure that allows full utilization of the catalytically active surface without intraparticle diffusional limitations.  相似文献   
42.
Endometriosis (EM) is an estrogen-dependent disease characterized by the presence of epithelial, stromal, and smooth muscle cells outside the uterine cavity. It is a chronic and debilitating condition affecting ~10% of women. EM is characterized by infertility and pain, such as dysmenorrhea, chronic pelvic pain, dyspareunia, dysuria, and dyschezia. Although EM was first described in 1860, its aetiology and pathogenesis remain uncertain. Recent evidence demonstrates that the peripheral nervous system plays an important role in the pathophysiology of this disease. Sensory nerves, which surround and innervate endometriotic lesions, not only drive the chronic and debilitating pain associated with EM but also contribute to a growth phenotype by secreting neurotrophic factors and interacting with surrounding immune cells. Here we review the role that peripheral nerves play in driving and maintaining endometriotic lesions. A better understanding of the role of this system, as well as its interactions with immune cells, will unearth novel disease-relevant pathways and targets, providing new therapeutics and better-tailored treatment options.  相似文献   
43.
Connexin43 (Cx43), the main gap junction and hemichannel forming protein in the urinary bladder, participates in the regulation of bladder motor and sensory functions and has been reported as an important modulator of day–night variations in functional bladder capacity. However, because Cx43 is expressed throughout the bladder, the actual role played by the detrusor and the urothelial Cx43 is still unknown. For this purpose, we generated urothelium-specific Cx43 knockout (uCx43KO) mice using Cre-LoxP system. We evaluated the day–night micturition pattern and the urothelial Cx43 hemichannel function of the uCx43KO mice by measuring luminal ATP release after bladder distention. In wild-type (WT) mice, distention-induced ATP release was elevated, and functional bladder capacity was decreased in the animals’ active phase (nighttime) when Cx43 expression was also high compared to levels measured in the sleep phase (daytime). These day–night differences in urothelial ATP release and functional bladder capacity were attenuated in uCx43KO mice that, in the active phase, displayed lower ATP release and higher functional bladder capacity than WT mice. These findings indicate that urothelial Cx43 mediated ATP signaling and coordination of urothelial activity are essential for proper perception and regulation of responses to bladder distension in the animals’ awake, active phase.  相似文献   
44.
45.
We investigate the estimation of illuminance flow using Histograms of Oriented Gradient features (HOGs). In a regression setting, we found for both ridge regression and support vector machines, that the optimal solution shows close resemblance to the gradient based structure tensor (also known as the second moment matrix).  相似文献   
46.
The characteristic hypothalamus square-wave secretion and its regulation of the pituitary are essential for the optimal functioning of the menstrual cycle. Here we consider two coupled models, where one mimics the square-wave secretion and the second, a self-replication chemical system, represents a regulated subsystem. We analyse the relation of the period and amplitude of the square-wave oscillations on the secondary oscillator, finding that both period and amplitude shape the secondary oscillations. Furthermore, a combined slow change of both period and amplitude are required for biologically suitable product concentrations of the secondary oscillator.  相似文献   
47.
Studies based on AC high voltage tests have been done at Cepel to investigate the performance of 800 kV bushar insulators under heavy wetting conditions. Insulators were tested which are now used on si...  相似文献   
48.
Societies and social scientists have long held the belief that exclusion induces ingratiation and conformity, an idea in contradiction to robust empirical evidence linking rejection with hostility and aggression. The classic literatures on ingratiation and conformity help resolve this contradiction by identifying circumstances under which rejection may trigger efforts to ingratiate. Jointly, findings from these literatures suggest that when people are given an opportunity to impress their rejecters, ingratiation is likely after rejection experiences that are harsh and that occur in important situations that threaten the individual's self-definition. Four studies tested the hypothesis that people high in rejection sensitivity and therefore dispositionally concerned about rejection will utilize opportunities to ingratiate after harsh rejection in situations that are self-defining. In 3 studies of situations that are particularly self-defining for men, rejection predicted ingratiation among men (but not women) who were high in rejection sensitivity. In a 4th study, harsh rejection in a situation particularly self-defining for women predicted ingratiation among highly rejection-sensitive women (but not men). These findings help identify the specific circumstances under which people are willing to act in socially desirable ways toward those who have rejected them harshly. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
49.
50.
Modern bipolar transistors use polysilicon emitters and an epitaxial grown silicon germanium (SiGe) base. For device optimization, both the SiGe base and the region of the diffused emitter is of special interest. In this paper, electron holography is applied to visualize and directly measure the two-dimensional distribution of the local potential in a high-performance SiGe heterojunction bipolar transistor. Special emphasis is put on investigating the region of the emitter diffused into the epitaxially grown base layer. In addition, we investigate the self-aligned base-link construction. We compare electron holographic measurements of the whole transistor to secondary ion mass spectrometric (SIMS) data and discuss the results.  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