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   43695篇
  免费   2821篇
  国内免费   239篇
电工技术   365篇
综合类   58篇
化学工业   8581篇
金属工艺   972篇
机械仪表   962篇
建筑科学   1358篇
矿业工程   100篇
能源动力   832篇
轻工业   7068篇
水利工程   376篇
石油天然气   458篇
武器工业   18篇
无线电   1946篇
一般工业技术   7173篇
冶金工业   10561篇
原子能技术   184篇
自动化技术   5743篇
  2023年   399篇
  2022年   385篇
  2021年   1014篇
  2020年   877篇
  2019年   958篇
  2018年   1575篇
  2017年   1564篇
  2016年   1682篇
  2015年   1353篇
  2014年   1647篇
  2013年   3355篇
  2012年   2610篇
  2011年   2406篇
  2010年   1930篇
  2009年   1798篇
  2008年   1811篇
  2007年   1654篇
  2006年   1302篇
  2005年   1035篇
  2004年   983篇
  2003年   885篇
  2002年   895篇
  2001年   672篇
  2000年   636篇
  1999年   662篇
  1998年   2528篇
  1997年   1794篇
  1996年   1165篇
  1995年   765篇
  1994年   641篇
  1993年   728篇
  1992年   314篇
  1991年   271篇
  1990年   255篇
  1989年   262篇
  1988年   245篇
  1987年   201篇
  1986年   195篇
  1985年   207篇
  1984年   194篇
  1983年   152篇
  1982年   170篇
  1981年   215篇
  1980年   179篇
  1979年   141篇
  1978年   124篇
  1977年   320篇
  1976年   652篇
  1973年   101篇
  1971年   118篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
Abdominal aortic aneurysm (AAA) is an inflammatory disease associated with marked changes in the cellular composition of the aortic wall. This study aims to identify microRNA (miRNA) expression in aneurysmal inflammatory cells isolated by laser microdissection from human tissue samples. The distribution of inflammatory cells (neutrophils, B and T lymphocytes, mast cells) was evaluated in human AAA biopsies. We observed in half of the samples that adventitial tertiary lymphoid organs (ATLOs) with a thickness from 0.5 to 2 mm were located exclusively in the adventitia. Out of the 850 miRNA that were screened by microarray in isolated ATLOs (n = 2), 164 miRNAs were detected in ATLOs. The three miRNAs (miR-15a-3p, miR-30a-5p and miR-489-3p) with the highest expression levels were chosen and their expression quantified by RT-PCR in isolated ATLOs (n = 4), M1 (n = 2) and M2 macrophages (n = 2) and entire aneurysmal biopsies (n = 3). Except for the miR-30a-5p, a similar modulation was found in ATLOs and the two subtypes of macrophages. The modulated miRNAs were then evaluated in the plasma of AAA patients for their potential as AAA biomarkers. Our data emphasize the potential of miR-15a-3p and miR-30a-5p as biomarkers of AAA but also as triggers of ATLO evolution. Further investigations will be required to evaluate their targets in order to better understand AAA pathophysiology.  相似文献   
33.
34.
35.
36.
ABSTRACT

In this paper, we review some algebraic control system. Precisely, linear and bilinear systems on Euclidean spaces and invariant and linear systems on Lie groups. The fourth classes of systems have a common issue: to any class, there exists an associated subgroup. From this object, we survey the controllability property. Especially, from those coming from our contribution to the theory.  相似文献   
37.
Context: The administration of pharmabiotics is a promising alternative to antimicrobial drugs for the treatment and/or prevention of female urogenital infections.

Objective: To design pharmabiotic formulations including bioactive ingredients of microbial origin combined with non-microbial substances and then to evaluate the stability of the combinations during freeze-drying and storage.

Materials and methods: Different formulations including Lactobacillus gasseri CRL 1263, Lactobacillus salivarius CRL 1328, salivaricin CRL 1328 (a bacteriocin) and non-microbial compounds (lactose, inulin and ascorbic acid) were assayed, and the ingredients were freeze-dried together or separately. The formulations were stored in gelatin capsules at 4?°C for 360?d.

Results: The viability of lactobacilli was affected to different extents depending on the strains and on the formulations assayed. L. salivarius and ascorbic acid were successfully combined only after the freeze-drying process. Salivaricin activity was not detected in formulations containing L. gasseri. However, when combined with ascorbic acid, lactose, inulin or L. salivarius, the bacteriocin maintained its activity for 360?d. The selected microorganisms proved to be compatible for their inclusion in multi-strain formulations together with lactose, inulin and ascorbic acid. Salivaricin could be included only in a L. salivarius CRL 1328 single-strain formulation together with non-microbial substances.

Conclusions: This study provides new insights into the design of urogenital pharmabiotics combining beneficial lactobacilli, salivaricin CRL 1328 and compounds with different functionalities.  相似文献   
38.
39.
40.
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