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   1471篇
  免费   19篇
  国内免费   1篇
电工技术   53篇
综合类   3篇
化学工业   285篇
金属工艺   42篇
机械仪表   21篇
建筑科学   11篇
能源动力   64篇
轻工业   84篇
水利工程   6篇
无线电   126篇
一般工业技术   244篇
冶金工业   476篇
原子能技术   23篇
自动化技术   53篇
  2023年   5篇
  2022年   11篇
  2021年   16篇
  2020年   8篇
  2019年   8篇
  2018年   17篇
  2017年   8篇
  2016年   11篇
  2015年   11篇
  2014年   25篇
  2013年   69篇
  2012年   40篇
  2011年   65篇
  2010年   31篇
  2009年   26篇
  2008年   39篇
  2007年   38篇
  2006年   39篇
  2005年   37篇
  2004年   32篇
  2003年   39篇
  2002年   38篇
  2001年   33篇
  2000年   26篇
  1999年   37篇
  1998年   203篇
  1997年   122篇
  1996年   69篇
  1995年   37篇
  1994年   48篇
  1993年   52篇
  1992年   18篇
  1991年   12篇
  1990年   29篇
  1989年   15篇
  1988年   12篇
  1987年   20篇
  1986年   16篇
  1985年   10篇
  1984年   8篇
  1983年   8篇
  1982年   8篇
  1981年   9篇
  1980年   7篇
  1979年   12篇
  1978年   11篇
  1977年   8篇
  1976年   24篇
  1974年   8篇
  1973年   6篇
排序方式: 共有1491条查询结果,搜索用时 0 毫秒
101.
To clarify the effects of microwave roasting on the distribution of tocopherols and FA of phospholipids within soybeans, whole soybeans (Glycine max) were treated by microwave and further evaluted as compared to a raw sample. Tocopherol homologs, measured using HPLC, and phospholipid profiles, quantified with GC, were determined in the seed coat, the embryonic axis, and selections of cotyledons separated from three cultivars. The tocopherols were predominantly detected in the axis, followed by the cotyledons, and then very little in the coat. As much as 25% of the individual tocopherols originally present in the coat were lost at 12 min of roasting, whereas <25% was lost in the cotyledons and the axis after 20 min of roasting. The greatest rate of phospholipid loss (P<0.05) was observed in PE, followed by PC and PI, and their changing patterns were more pronounced in the coat than in the cotyledons or the axis. Thus, tocopherol content and phospholipid profiles change with microwave roasting according to tissue.  相似文献   
102.
Glioblastoma (GBM) is the leading malignant intracranial tumor and is associated with a poor prognosis. Highly purified, activated natural killer (NK) cells, designated as genuine induced NK cells (GiNKs), represent a promising immunotherapy for GBM. We evaluated the anti-tumor effect of GiNKs in association with the programmed death 1(PD-1)/PD-ligand 1 (PD-L1) immune checkpoint pathway. We determined the level of PD-1 expression, a receptor known to down-regulate the immune response against malignancy, on GiNKs. PD-L1 expression on glioma cell lines (GBM-like cell line U87MG, and GBM cell line T98G) was also determined. To evaluate the anti-tumor activity of GiNKs in vivo, we used a xenograft model of subcutaneously implanted U87MG cells in immunocompromised NOG mice. The GiNKs expressed very low levels of PD-1. Although PD-L1 was expressed on U87MG and T98G cells, the expression levels were highly variable. Our xenograft model revealed that the retro-orbital administration of GiNKs and interleukin-2 (IL-2) prolonged the survival of NOG mice bearing subcutaneous U87MG-derived tumors. PD-1 blocking antibodies did not have an additive effect with GiNKs for prolonging survival. GiNKs may represent a promising cell-based immunotherapy for patients with GBM and are minimally affected by the PD-1/PD-L1 immune evasion axis in GBM.  相似文献   
103.
由于环境污染问题,取代传统的基于引导的PZT自由引导压电材料得到了发展。其中CaBi4Ti4O15由于其多极性显示出铁和压电特性。在早期研究中,Ca-Bi-Ti合成醇盐的旋转涂层薄膜作为一个前期方案,通过钙、铋的氧化物和锑的异丙氧化物在酒精和2-甲氧基乙氧基混合物中的化学反应已经很好地合  相似文献   
104.
This paper describes a validation system for an SLDRAM interface. The SLDRAM system utilizes two techniques to achieve a high data-transfer rate with a conventional module mounting style. The first technique is a source-synchronization scheme. Since the chip that transmits data also supplies the data clock, the clock and data are completely synchronous. The second is the timing vernier technique. A wait time for output data is programmable in each SLDRAM. Therefore, the time at which data arrive at the controller from any SLDRAM can be set by the controller with a 200-ps step size. The validation chip is designed to emulate these operations. The chip is fabricated using a 0.35-μm CMOS process technology and packaged in a conventional 0.65-mm pitch thin small out-line package, mounted on a single-chip module, and put into an eight-module system. A stub series terminated logic (SSTL)-like interface is adopted for high-speed signals. From system-level measurements, the data eye width of 600 ps is obtained at a data rate of 600 Mbps. Errorless data transmission is observed in both read and write operations in a bit-error rate testing. The validation system has successfully demonstrated a data-transmission rate of 1.2 GB/s (600 Mbit/s/pin) using source-synchronization and timing vernier techniques at the supply voltage of 2.5 V  相似文献   
105.
It has been reported through simulations that Hopfield networks for crossbar switching almost always achieve the maximum throughput. It has therefore appeared that Hopfield networks of high-speed computation by parallel processing could possibly be used for crossbar switching. However, it has not been determined whether they can always achieve the maximum throughput. In the paper, the capabilities and limitations of a Hopfield network for crossbar switching are considered. The Hopfield network considered in the paper is generated from the most familiar and seemingly the most powerful neural representation of crossbar switching. Based on a theoretical analysis of the network dynamics, we show what switching control the Hopfield network can or cannot produce. Consequently, we are able to show that a Hopfield network cannot always achieve the maximum throughput.  相似文献   
106.
A case study of the application of a distributed control scheme to a power system control is presented. In addition, an investigation has been conducted into voltage control. Combined injection of VAr-compensating devices controlled by distributed expert systems has been proposed as a measure to maintain voltage stability in a power system under heavy loading conditions. A simulation study has been carried out by using five workstations that represent a power system and four VAr-compensating devices. The results demonstrate the effectiveness of the proposed system for voltage recovery  相似文献   
107.
108.
我们通过对材料和制备条件的精细化处理,生产出一种在低刷新频率下无闪烁和图像迟滞现象的反射式显示器。该显示器的功耗非常低,且可在宽温度范围内工作,是未来移动显示器件的潜力平台。  相似文献   
109.
110.
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