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   3172篇
  免费   21篇
电工技术   45篇
综合类   1篇
化学工业   109篇
金属工艺   43篇
机械仪表   37篇
建筑科学   51篇
矿业工程   3篇
能源动力   28篇
轻工业   80篇
水利工程   5篇
石油天然气   2篇
无线电   132篇
一般工业技术   226篇
冶金工业   2260篇
原子能技术   8篇
自动化技术   163篇
  2023年   5篇
  2021年   11篇
  2020年   10篇
  2019年   11篇
  2018年   12篇
  2017年   18篇
  2016年   12篇
  2015年   10篇
  2014年   21篇
  2013年   44篇
  2012年   24篇
  2011年   56篇
  2010年   55篇
  2009年   28篇
  2008年   43篇
  2007年   30篇
  2006年   39篇
  2005年   33篇
  2004年   28篇
  2003年   39篇
  2002年   34篇
  2001年   37篇
  2000年   36篇
  1999年   84篇
  1998年   713篇
  1997年   378篇
  1996年   258篇
  1995年   171篇
  1994年   107篇
  1993年   141篇
  1992年   24篇
  1991年   39篇
  1990年   45篇
  1989年   45篇
  1988年   31篇
  1987年   39篇
  1986年   28篇
  1985年   42篇
  1984年   26篇
  1983年   16篇
  1982年   32篇
  1981年   21篇
  1980年   22篇
  1979年   11篇
  1978年   16篇
  1977年   69篇
  1976年   131篇
  1975年   14篇
  1974年   5篇
  1972年   9篇
排序方式: 共有3193条查询结果,搜索用时 31 毫秒
41.
42.
43.
44.
45.
Previous publications have shown how a combination of X-ray computed tomography and spherical harmonic series could be used to characterize the 3-D shape of rocks used for aggregates in concrete. The X-ray computed tomography was used to obtain the raw 3-D numerical data for the coordinates of the aggregate surface. In this paper, we demonstrate how laser detection and ranging (LADAR) numerical data can replace X-ray computed tomography data and be used in conjunction with spherical harmonic series analysis to analyze the 3-D shape of aggregates.  相似文献   
46.
The primary purpose of this investigation was to compare tissue fixation security by simple sutures versus mattress sutures in transosseous rotator cuff repair. These two repair techniques were each performed in 17 human cadaver shoulders, with two bone tunnels being used for the repair by two simple sutures and two other bone tunnels being used for the repair by one mattress suture. The repairs were loaded to failure in a servohydraulic materials test system. Rotator cuff repair by simple sutures was found to be significantly stronger than repair by mattress sutures (P = .0007). The average ultimate load to failure for the simple suture construct (189.62 N) was 39.72% greater than that for the mattress suture construct (135.71 N). Most of the failures occurred by suture breakage at the knot. Load-sharing by multiple suture tails and multiple knots in the simple suture configuration likely contributed to its superior strength characteristics compared with the mattress suture configuration.  相似文献   
47.
We report the clinical and pathologic findings of two patients with sporadic visceral myopathy. Both presented with chronic intestinal pseudo-obstruction that necessitated colectomy. Microscopically, typical changes of primary visceral myopathy were present, including variable fibrous replacement of the muscularis externa and vacuolar degeneration of myocytes. In addition, the muscle cells contained cytoplasmic inclusions that have only been recently reported in visceral myopathy. These inclusions were numerous and easily visible in routine hematoxylin-eosin-stained sections but greatly enhanced by periodic acid-Schiff staining. They were reactive immunohistochemically at their periphery and were seen to be myofibrils at various stages of degeneration on electron microscopy. Inclusions were present in both muscularis externae and muscularis mucosae and were identified in mucosal biopsy specimens, providing a means of diagnosing this type of myopathic change on endoscopic biopsies.  相似文献   
48.
The IgE-mediated allergic response involves a series of physiological pathways that result in the array of symptoms commonly associated with allergy. This article describes the mediators that prompt specific clinical responses and identifies those at risk for latex hypersensitivity.  相似文献   
49.
The P2X3 receptor subunit, a member of the P2X family of ATP-gated ion channels, is almost exclusively localized in sensory neurons. In the present study, we sought to gain insight into the role of P2X3 and P2X3-containing neurons in sensory transmission, using immunohistochemical approaches. In rat dorsal root ganglia (DRG), P2X3-immunoreactivity (-ir) was observed in small- and medium-sized neurons. Approximately 40% of DRG neuronal profiles in normal rats contained P2X3-ir. In rats that had received neonatal capsaicin treatment, the number of P2X3-positive neurons was decreased by approximately 70%. Analysis of the colocalization of P2X3-ir with cytochemical markers of DRG neurons indicated that approximately 94% of the P2X3-positive neuronal profiles were labelled by isolectin B4 from Bandeiraea simplicifolia, while only 3% contained substance P-ir, and 7% contained somatostatin-ir. In dorsal horn of rat spinal cord, P2X3-ir was observed in the inner portion of lamina II and was reduced subsequent to dorsal rhizotomy, as well as subsequent to neonatal capsaicin treatment. Finally, P2X3-ir accumulated proximal to the site of sciatic nerve ligation, and was seen in nerve fibres in skin and corneal epithelium. In summary, our results suggest that P2X3 is expressed by a functionally heterogeneous population of BSI-B4-binding sensory neurons, and is transported into both central and peripheral processes of these neurons.  相似文献   
50.
In this paper, characterization is given of clinical and biochemical features of VH B course against the background of narcomania. Recordable in such patient populations are high percentage of delta hepatitis (14.2%), unusual severity of the intoxication syndrome, protracted course with exacerbations (12.2%) and recurrences (8%), outcome being a chronic hepatitis (14.2%), slower normalization of biochemical indicators, persistently low ratio of AIAT activity in diluted and whole blood sera. The persistence of viral markers in drug addicts discharged from the hospital (68%) is fraught with danger of spreading viral hepatitis of prophylactic measures are not strictly observed.  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