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   3442篇
  免费   75篇
  国内免费   4篇
电工技术   163篇
综合类   9篇
化学工业   687篇
金属工艺   82篇
机械仪表   55篇
建筑科学   63篇
矿业工程   2篇
能源动力   106篇
轻工业   261篇
水利工程   6篇
石油天然气   2篇
无线电   400篇
一般工业技术   480篇
冶金工业   895篇
原子能技术   45篇
自动化技术   265篇
  2023年   20篇
  2022年   34篇
  2021年   62篇
  2020年   24篇
  2019年   25篇
  2018年   44篇
  2017年   39篇
  2016年   49篇
  2015年   38篇
  2014年   79篇
  2013年   129篇
  2012年   115篇
  2011年   139篇
  2010年   101篇
  2009年   107篇
  2008年   130篇
  2007年   120篇
  2006年   87篇
  2005年   113篇
  2004年   81篇
  2003年   104篇
  2002年   80篇
  2001年   77篇
  2000年   69篇
  1999年   87篇
  1998年   368篇
  1997年   210篇
  1996年   140篇
  1995年   98篇
  1994年   91篇
  1993年   82篇
  1992年   35篇
  1991年   38篇
  1990年   30篇
  1989年   49篇
  1988年   26篇
  1987年   24篇
  1986年   32篇
  1985年   27篇
  1984年   31篇
  1983年   27篇
  1982年   21篇
  1981年   29篇
  1980年   27篇
  1979年   24篇
  1978年   27篇
  1977年   30篇
  1976年   48篇
  1974年   15篇
  1973年   9篇
排序方式: 共有3521条查询结果,搜索用时 15 毫秒
21.
Neoadjuvant endocrine treatment prior to radical prostatectomy for prostate cancer confined to pelvis has of some value to prevent progression although there are many controversies. In order to improve the prognosis of locally advanced prostate cancer (stage B2 and C), definitive radiotherapy with neoadjuvant endocrine therapy has been investigated. Endocrine therapy reduces the volume of prostate, thus reduces the amount of side effect via reducing the area of irradiated normal tissue. Effect of radiation and that of endocrine therapy to induce apoptosis might be synergistic. The result is favorable although the follow-up period is too short. Further studies are needed to make conclusion.  相似文献   
22.
Two patients with polymyositis (PM) or dermatomyositis (DM) complicated with massive pleural effusion are reported here. Both patients presented a high-grade fever, pleural effusion prominent on the right, and good response to steroid therapy. In a 50-year-old woman with PM, combined process of pleural inflammation, cardiomyopathy and coexisting hypothyroidism were considered to be responsible for the accumulation of the massive pleural effusion. However, in a 34-year-old man with DM, pleural inflammation associated with interstitial pneumonia or pleural microvasculopathy in DM was considered to be responsible for the accumulation of the massive pleural effusion.  相似文献   
23.
24.
We report here a novel type of ceramidase of Pseudomonas aeruginosa AN17 isolated from the skin of a patient with atopic dermatitis. The enzyme was purified 83,400-fold with an overall yield of 21.1% from a culture supernatant of strain AN17. After being stained with a silver staining solution, the purified enzyme showed a single protein band, and its molecular mass was estimated to be 70 kDa on SDS-polyacrylamide gel electrophoresis. The enzyme showed quite wide specificity for various ceramides, i.e. it hydrolyzed ceramides containing C12:0-C18:0 fatty acids and 7-nitrobenz-2-oxa-1, 3-diazole-labeled dodecanoic acid, and not only ceramide containing sphingosine (d18:1) or sphinganine (d18:0) but also phytosphingosine (t18:0) as the long-chain base. However, the enzyme did not hydrolyze galactosylceramide, sulfatide, GM1, or sphingomyelin, and thus was clearly distinguished from a Pseudomonas sphingolipid ceramide N-deacylase (Ito, M., Kurita, T., and Kita, K. (1995) J. Biol. Chem. 270, 24370-24374). This bacterial ceramidase had a pH optimum of 8.0-9.0, an apparent Km of 139 microM, and a Vmax of 5.3 micromol/min/mg using N-palmitoylsphingosine as the substrate. The enzyme appears to require Ca2+ for expression of the activity. Interestingly, the 70-kDa protein catalyzed a reversible reaction in which the N-acyl linkage of ceramide was either cleaved or synthesized. Our study demonstrated that ceramidase is widely distributed from bacteria to mammals.  相似文献   
25.
We report a nephrotic syndrome patient with eosinophilia who developed ileus, epigastralgia and malabsorption due to strongyloidiasis which became symptomatic by steroid therapy. The patient was then treated with thiabendazole and recovered. A percutaneous renal biopsy revealed minimal change nephrotic syndrome. This renal injury may be brought on by severe infection of Strongyloides stercoralis. It is important to rule out strongyloidiasis prior to corticosteroid therapy to patients from eosinophilia endemic areas.  相似文献   
26.
Circularly polarised printed antenna fed by coplanar waveguide   总被引:1,自引:0,他引:1  
Matsuzawa  S. Ito  K. 《Electronics letters》1996,32(22):2035-2036
A new structure of the circularly polarised printed antenna fed by coplanar waveguide (CPW) is proposed. FDTD analysis predicts the radiation of the circularly polarised wave from the antenna. The validity of this analysis is established by comparing with experimental results  相似文献   
27.
28.
新型陶瓷与熔融盐复合蓄热材料优化组合的数值模拟   总被引:12,自引:0,他引:12  
将高温熔融盐相变蓄热材料和陶瓷固相蓄热材料进行复合 ,成功地研制成了能快速吸热和放热且蓄热密度高、蓄热量大的新型复合蓄热材料。分别以Al2 O3 ,MgO ,SiC为代表的陶瓷材料与 6 0LiF 40NaF ,5 0LiF 5 0KF ,6 0 .1NaCl 39.9MgCl2 ,LiH等为代表的 10余种高温熔融盐材料为复合研究对象 ,对复合蓄热材料的蓄热密度等与温度、复合材料中熔融盐的含量、材料种类间的关系进行了数值模拟研究 ,得到了对复合材料的优化设计具有指导意义的结论  相似文献   
29.
We report fast computation of computer-generated holograms (CGHs) using Xeon Phi coprocessors, which have massively x86-based processors on one chip, recently released by Intel. CGHs can generate arbitrary light wavefronts, and therefore, are promising technology for many applications: for example, three-dimensional displays, diffractive optical elements, and the generation of arbitrary beams. CGHs incur enormous computational cost. In this paper, we describe the implementations of several CGH generating algorithms on the Xeon Phi, and the comparisons in terms of the performance and the ease of programming between the Xeon Phi, a CPU and graphics processing unit (GPU).  相似文献   
30.
Schaefer-Sindlinger  A.  Lappas  I.  Vogt  C. D.  Ito  T.  Kurachi  H.  Makino  M.  Takahashi  A. 《Topics in Catalysis》2007,42(1-4):307-317
This paper will give an overview about the filter development for diesel particulate emission control in automotive applications. The material development for passenger car diesel particulate filters led to new materials like silicon carbide while for heavy duty applications still Cordierite plays a major role. But in the future other materials might also be used for passenger cars. This paper will show the basic difference between both applications and describe the material design in terms of filter properties (base material, back pressure aspects, filtration efficiency, coating impact). Current application on vehicles with catalysed soot filters (CSF) with and without oxidation catalyst will be presented. Furthermore an outlook will be given on materials for catalysed soot filters for the future.  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