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   51384篇
  免费   2601篇
  国内免费   61篇
电工技术   410篇
综合类   39篇
化学工业   9953篇
金属工艺   955篇
机械仪表   1162篇
建筑科学   1655篇
矿业工程   95篇
能源动力   1219篇
轻工业   7022篇
水利工程   499篇
石油天然气   218篇
武器工业   6篇
无线电   3068篇
一般工业技术   8992篇
冶金工业   11323篇
原子能技术   282篇
自动化技术   7148篇
  2024年   95篇
  2023年   474篇
  2022年   678篇
  2021年   1336篇
  2020年   1037篇
  2019年   1013篇
  2018年   1899篇
  2017年   1925篇
  2016年   2003篇
  2015年   1443篇
  2014年   1874篇
  2013年   3570篇
  2012年   3072篇
  2011年   3001篇
  2010年   2314篇
  2009年   2156篇
  2008年   2323篇
  2007年   2008篇
  2006年   1520篇
  2005年   1240篇
  2004年   1120篇
  2003年   1013篇
  2002年   925篇
  2001年   598篇
  2000年   604篇
  1999年   736篇
  1998年   3633篇
  1997年   2214篇
  1996年   1448篇
  1995年   861篇
  1994年   727篇
  1993年   693篇
  1992年   247篇
  1991年   262篇
  1990年   251篇
  1989年   244篇
  1988年   223篇
  1987年   193篇
  1986年   198篇
  1985年   244篇
  1984年   213篇
  1983年   166篇
  1982年   181篇
  1981年   192篇
  1980年   179篇
  1979年   148篇
  1978年   129篇
  1977年   221篇
  1976年   446篇
  1975年   96篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
62.
We compared the performance of patients with frontal excisions, patients with temporal excisions and controls in tasks involving speeded choice responses in which a number of variables were manipulated including: perceptual difficulty, stimulus and response set-size, associative complexity, and spatial stimulus-response compatibility. Response times were sensitive to all manipulations but did not show any group differences. The error rates of the three groups were equally affected by perceptual difficulty and response set-size but frontals were preferentially affected by spatial S-R compatibility, associative complexity, and the number of stimuli per response. The results are consistent with a basic deficit in response selection processes which could underly many problems produced by frontal lesions.  相似文献   
63.
64.
65.
Software Quality Journal - Energy consumption of software has been becoming increasingly significant, since it can vary according to how the software has been developed. In recent years, developers...  相似文献   
66.
The different groups and/or classes among phenolic acids and aldehydes identified during the elaboration process of "fino" sherry wine have been studied. The study was carried out using different processes during the elaboration of the wine and we have attempted to establish whether the different treatments of the grape affect these groupings. The study was undertaken by means of cluster and multifactorial analysis on the data obtained by the quantitative determination of phenolic acids and aldehydes during vinification and in experiments carried out on the grape under different mechanical treatments. The analysis of phenolic acids and aldehydes was done with HPLC, using a C-18 mu-Bondapak and a stepwise composite gradient. The samples were previously extracted with ethylic ether.  相似文献   
67.
Immune checkpoint inhibitors (ICIs) have demonstrated remarkable efficacy in a growing number of malignancies. However, overcoming primary or secondary resistances is difficult due to pharmacokinetics issues and side effects associated with high systemic exposure. Local or regional expression of monoclonal antibodies (mAbs) using gene therapy vectors can alleviate this problem. In this work, we describe a high-capacity adenoviral vector (HCA-EFZP-aPDL1) equipped with a mifepristone-inducible system for the controlled expression of an anti-programmed death ligand 1 (PD-L1) blocking antibody. The vector was tested in an immune-competent mouse model of colorectal cancer based on implantation of MC38 cells. A single local administration of HCA-EFZP-aPDL1 in subcutaneous lesions led to a significant reduction in tumor growth with minimal release of the antibody in the circulation. When the vector was tested in a more stringent setting (rapidly progressing peritoneal carcinomatosis), the antitumor effect was marginal even in combination with other immune-stimulatory agents such as polyinosinic-polycytidylic acid (pI:C), blocking mAbs for T cell immunoglobulin, mucin-domain containing-3 (TIM-3) or agonistic mAbs for 4-1BB (CD137). In contrast, macrophage depletion by clodronate liposomes enhanced the efficacy of HCA-EFZP-aPDL1. These results highlight the importance of addressing macrophage-associated immunoregulatory mechanisms to overcome resistance to ICIs in the context of colorectal cancer.  相似文献   
68.
Tin electrodeposition in its initial stages in acid sulfate/gluconate baths was studied with varying tin and gluconate concentrations using potential-controlled electrochemical techniques. The deposit morphology was observed by scanning electron microscopy (SEM). A comparison with tin electrodeposition from acid sulfate baths in the absence of gluconate was also carried out. Use of a highly acidic bath leads to nonuniform deposits, even in the presence of gluconate; at pH 4 deposits are uniform, brilliant and suitable for finishing applications. Tin crystallites have a well defined morphology which depends on bath agitation conditions. In the absence of agitation, the crystallites have the same tetragonal shape as in a sulfate bath without gluconate.  相似文献   
69.
Conclusions A laboratory installation for flame guncreting was designed, built, and tested. A method was developed for flame guncreting of basic refractories. The guncreted layer obtained as a result of flame guncreting is formally bonded with the refractory, and in its density and structure, is significantly better than it.Translated from Ogneupory, No.2, pp.54–57, February, 1967.  相似文献   
70.
The catalytic activities of WCI6Ph4Sn, MoCl5Ph4Sn and tetrabenzyltitanium were examined in the polymerization of acetylene. The structure, morphology and electrical conductivity of the doped and non doped polyacetylene were also studied.  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