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   6563篇
  免费   44篇
  国内免费   2篇
电工技术   28篇
化学工业   230篇
金属工艺   38篇
机械仪表   40篇
建筑科学   52篇
矿业工程   7篇
能源动力   61篇
轻工业   150篇
水利工程   26篇
石油天然气   1篇
无线电   251篇
一般工业技术   269篇
冶金工业   5253篇
原子能技术   19篇
自动化技术   184篇
  2021年   10篇
  2020年   15篇
  2019年   17篇
  2018年   27篇
  2017年   22篇
  2016年   30篇
  2015年   19篇
  2014年   27篇
  2013年   75篇
  2012年   57篇
  2011年   69篇
  2010年   46篇
  2009年   57篇
  2008年   59篇
  2007年   76篇
  2006年   54篇
  2005年   53篇
  2004年   54篇
  2003年   37篇
  2002年   48篇
  2001年   53篇
  2000年   31篇
  1999年   198篇
  1998年   1557篇
  1997年   859篇
  1996年   591篇
  1995年   314篇
  1994年   292篇
  1993年   316篇
  1992年   54篇
  1991年   101篇
  1990年   82篇
  1989年   116篇
  1988年   104篇
  1987年   77篇
  1986年   88篇
  1985年   81篇
  1984年   17篇
  1983年   27篇
  1982年   37篇
  1981年   41篇
  1980年   70篇
  1979年   24篇
  1978年   34篇
  1977年   150篇
  1976年   301篇
  1975年   18篇
  1974年   19篇
  1973年   14篇
  1972年   14篇
排序方式: 共有6609条查询结果,搜索用时 31 毫秒
81.
82.
83.
84.
This article is a discussion of the use of narrow-band light sources coupled with cameras equipped with band-pass filters to document patterned injuries on human skin. Several case reports are included.  相似文献   
85.
We have isolated a putative serine/threonine receptor kinase gene with an expression pattern indicating that it may play a role in the stylar response to pollination. Differential display PCR was used to select tobacco mRNAs with increased accumulation following pollination. NTS16, a cDNA identified by this method, is homologous to a ca. 2.4 kb mRNA primarily expressed in pistil tissues. Levels of this mRNA increase during floral development and are further increased by pollination reaching maximal accumulation 12-18 hours after pollination and then declining. mRNA levels can also be increased by the application of ethylene to unpollinated flowers. A polypeptide encoded by the NTS 16 open reading frame has sequence similarity to the catalytic domain of several receptor protein kinases from plants including the S-receptor kinases implicated in the rejection of self-pollen in Brassica species and the Pto gene product of tomato which confers resistance to a bacterial pathogen.  相似文献   
86.
AIMS/BACKGROUND: To characterise clinically a large kindred segregating retinitis pigmentosa and sensorineural hearing impairment in an autosomal dominant pattern and perform genetic linkage studies in this family. Extensive linkage analysis in this family had previously excluded the majority of loci shown to be involved in the aetiologies of RP, some other forms of inherited retinal degeneration, and inherited deafness. METHODS: Members of the family were subjected to detailed ophthalmic and audiological assessment. In addition, some family members underwent skeletal muscle biopsy, electromyography, and electrocardiography. Linkage analysis using anonymous microsatellite markers was performed on DNA samples from all living members of the pedigree. RESULTS: Patients in this kindred have a retinopathy typical of retinitis pigmentosa in addition to a hearing impairment. Those members of the pedigree examined demonstrated a subclinical myopathy, as evidence by abnormal skeletal muscle histology, electromyography, and electrocardiography. LOD scores of Zmax = 3.75 (theta = 0.10), Zmax = 3.41 (theta = 0.10), and Zmax = 3.25 (theta = 0.15) respectively were obtained with the markers D9S118, D9S121, and ASS, located on chromosome 9q34-qter, suggesting that the causative gene in this family may lie on the long arm (q) of chromosome 9. CONCLUSIONS: These data indicate that the gene responsible for the phenotype in this kindred is located on chromosome 9 q. These data, together with evidence that a murine deafness gene is located in a syntenic area of the mouse genome, should direct the research community to consider this area as a candidate region for retinopathy and/or deafness genes.  相似文献   
87.
88.
Ice observations, results, and conclusions are summarized for the March 1987 Labrador Ice Margin Experiment (LIMEX'87), an international oceanographic study conducted in the pack ice of the Grand Banks area off the coast of Newfoundland. Included are the ice extent, flow size and thickness, ice kinematics and rheology, ice microwave properties, oceanic properties under the ice, and penetration of swell into the ice  相似文献   
89.
The first commercial application of the Sherritt two-stage zinc pressure leach process commenced operation at the Hudson Bay Mining and Smelting Company metallurgical complex in Flin Flon, Manitoba (Canada), on July 2, 1993. The start-up was relatively smooth, and full design rate for the plant was achieved by September 12, 1993. Since that time, zinc extraction in the zinc pressure leach plant has consistently been in excess of 98%, and production has continued to exceed expectations. The successful operation of the Hudson Bay plant represents a significant advancement of zinc processing technology, especially with respect to meeting the environmental challenge faced by zinc plants today.  相似文献   
90.
Familial haemophagocytic lymphohistiocytosis (HLH) is a disease with a very poor prognosis unless patients receive a bone marrow transplant. It is often difficult to find an HLA-matched donor and haploidentical familial donors may be considered. The main complication of this type of transplant is graft rejection. We describe a patient with familial HLH who received a haploidentical transplant using both mobilized peripheral blood and bone marrow stem cells in an attempt to overcome graft rejection by increasing the stem cell dose. The peripheral blood stem cell inoculum was CD34 enriched using a Cellpro column and T-cell depleted by Campath-1M, the patient received conditioning for a matched sibling donor transplant with the addition of Campath 1G. There was rapid and full engraftment and the patient remains disease free at 5 months. This technique may be applicable for other fatal inborn errors in the absence of an HLA-matched donor.  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