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   6369篇
  免费   609篇
  国内免费   476篇
电工技术   548篇
综合类   593篇
化学工业   671篇
金属工艺   389篇
机械仪表   525篇
建筑科学   449篇
矿业工程   176篇
能源动力   112篇
轻工业   830篇
水利工程   265篇
石油天然气   127篇
武器工业   66篇
无线电   582篇
一般工业技术   469篇
冶金工业   692篇
原子能技术   83篇
自动化技术   877篇
  2024年   44篇
  2023年   109篇
  2022年   201篇
  2021年   338篇
  2020年   212篇
  2019年   125篇
  2018年   151篇
  2017年   171篇
  2016年   154篇
  2015年   281篇
  2014年   359篇
  2013年   414篇
  2012年   461篇
  2011年   469篇
  2010年   495篇
  2009年   482篇
  2008年   457篇
  2007年   467篇
  2006年   414篇
  2005年   323篇
  2004年   220篇
  2003年   137篇
  2002年   120篇
  2001年   134篇
  2000年   107篇
  1999年   49篇
  1998年   142篇
  1997年   100篇
  1996年   56篇
  1995年   36篇
  1994年   25篇
  1993年   33篇
  1992年   11篇
  1991年   22篇
  1990年   21篇
  1989年   18篇
  1988年   15篇
  1987年   13篇
  1986年   12篇
  1985年   6篇
  1981年   1篇
  1980年   6篇
  1979年   1篇
  1978年   1篇
  1977年   9篇
  1976年   24篇
  1975年   2篇
  1965年   2篇
  1959年   1篇
  1951年   1篇
排序方式: 共有7454条查询结果,搜索用时 15 毫秒
991.
对广西蔗糖行业的用油(脂)状况进行调查,发现传统的设备和润滑管理模式已不适应现代化糖厂的要求,应根据设备实际用油(脂)状况,通过采取技术改进和正确选用相应油脂等措施,提高设备润滑水平。  相似文献   
992.
BACKGROUND: Immunodominant epitopes of Bet v 1a had been identified before, using recombinant (r) Bet v 1a-reactive T cell clones generated from peripheral blood mononuclear cells of patients allergic to birch pollen. This study aimed at evaluating the T cell-stimulating capacity of immunodominant Bet v 1a-derived peptides in a polyclonal system corresponding more closely to the situation in patients. METHODS: Short-term T cell lines (TCL) were established in presence of a protein extract of birch pollen (BP extract). TCL proliferation induced by the BP extract, by natural Bet v 1, rBet v 1a, rBet v 2 or 5 selected immunodominant Bet v 1a-derived peptides was determined. RESULTS: Consistent with the knowledge that Bet v 1 is the major IgE-binding allergen of birch pollen, we found comparable T cell reactivity to natural Bet v 1 and the BP extract within the majority of the TCL. Accordingly, the response to rBet v 2 was low compared with the reactivity to the BP extract. The response of the TCL to rBet v 1a proved to be highly heterogeneous. Furthermore, the TCL response to the 5 immunodominant Bet v 1a-derived peptides showed considerable diversity. The proliferative responses of most TCL (with one exception) following stimulation by these peptides were low, in relation to the expansion induced by the BP extract. CONCLUSION: These findings argue against the use of selected peptides derived from Bet v 1a in specific immunotherapy of patients with birch allergy.  相似文献   
993.
Chromosome band 11q23 is frequently involved in acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) de novo, as well as in myelodysplastic syndromes (MDS) and lymphoma. Five percent to 15% of patients treated with chemotherapy for a primary neoplasm develop therapy-related AML (t-AML) that may show rearrangements, usually translocations involving band 11q23 or, less often, 21q22. These leukemias develop after a relatively short latent period and often follow the use of drugs that inhibit the activity of DNA-topoisomerase II (topo II). We previously identified a gene, MLL (myeloid-lymphoid leukemia or mixed-lineage leukemia), at 11q23 that is involved in the de novo leukemias. We have studied 17 patients with t-MDS/t-AML, 12 of whom had cytogenetically detectable 11q23 rearrangements. Ten of the 12 t-AML patients had received topo II inhibitors and 9 of these, all with balanced translocations of 11q23, had MLL rearrangements on Southern blot analysis. None of the patients who had not received topo II inhibitors showed an MLL rearrangement. Of the 5 patients lacking 11q23 rearrangements, some of whom had monoblastic features, none had an MLL rearrangement, although 4 had received topo II inhibitors. Our study indicates that the MLL gene rearrangements are similar both in AML that develops de novo and in t-AML. The association of exposure to topo II-reactive chemotherapy with 11q23 rearrangements involving the MLL gene in t-AML suggests that topo II may play a role in the aberrant recombination events that occur in this region both in AML de novo and in t-AML.  相似文献   
994.
An analysis of the result of administering electroconvulsive therapy (E.C.T.) to 292 patients suffering predominantly from psychosis and depression is presented. The results show that the courses of E.C.T. administered range from three to twenty-five. The most frequently administered course was six to eight. Favourable response to treatment was reported in all diagnostic groups immediately after completing the course but less so in cases of depression and paranoid schizophrenia. The reasons thought to account for this were discussed. It is concluded that there is need for careful selection of patients for E.C.T.  相似文献   
995.
In a study of 32 unrelated Arab patients with juvenile myoclonic epilepsy (JME), we compared the frequencies of human leukocyte antigen (HLA) class I and II alleles with those of unrelated healthy controls. A significant difference between the phenotypic frequencies in JME patients and controls was observed for DRW13, the split of DRW6 (37.5 vs 11% of controls). The strength of association as measured by the relative risk was 4.85 for this antigen (p = 0.002). The possible association of JME with HLA-DRW6 recently reported in Caucasians was confirmed in this study. This finding speaks for the homogeneity of the disease among Arabic and Caucasian JME patients. The existence of this association is evidence of a locus in the HLA region that influences expression of JME.  相似文献   
996.
997.
998.
We examined the expression patterns of the DP5 gene, which encodes a protein with apoptosis-inducing activity, in the developing nervous system of mice. This gene was primarily expressed in the spinal motor neurons and peripheral sensory ganglia of mouse embryos and transiently in the postnatal brain, particularly in the entorhinal cortex and hippocampus. These expression patterns suggest that the DP5 gene may be involved in the apoptosis, if not all, of the developing nervous system.  相似文献   
999.
1000.
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