首页 | 官方网站   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   1736085篇
  免费   49766篇
  国内免费   18657篇
工业技术   1804508篇
  2022年   14943篇
  2021年   26898篇
  2020年   20708篇
  2019年   21594篇
  2018年   22345篇
  2017年   22848篇
  2016年   28693篇
  2015年   28626篇
  2014年   43402篇
  2013年   104830篇
  2012年   52284篇
  2011年   65142篇
  2010年   58583篇
  2009年   66440篇
  2008年   58492篇
  2007年   54551篇
  2006年   59996篇
  2005年   52071篇
  2004年   48885篇
  2003年   47839篇
  2002年   46220篇
  2001年   42482篇
  2000年   41785篇
  1999年   42091篇
  1998年   44884篇
  1997年   40570篇
  1996年   38128篇
  1995年   33722篇
  1994年   31291篇
  1993年   29850篇
  1992年   27676篇
  1991年   24220篇
  1990年   24298篇
  1989年   23098篇
  1988年   21346篇
  1987年   19404篇
  1986年   18618篇
  1985年   21719篇
  1984年   22094篇
  1983年   20042篇
  1982年   19190篇
  1981年   19216篇
  1980年   17768篇
  1979年   18291篇
  1978年   17532篇
  1977年   16607篇
  1976年   16815篇
  1975年   15567篇
  1974年   15121篇
  1973年   15195篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
33.
34.
Multimedia Tools and Applications - The three-dimensional models of brain tumors serve as diagnostic assistance for physicians, surgeons, and radiologists. The proposed system establishes an...  相似文献   
35.
Zhang  Nan  Zhao  Man  Liu  Guangfa  Wang  Jiaoyang  Chen  Yunzhi  Zhang  Zhengjian 《Journal of Materials Science》2022,57(19):8687-8700
Journal of Materials Science - A green modification method for effectively enhancing toughness of PLA was established. Herein, alkaline lignin (LG) was firstly alkylated with dodecane, and then...  相似文献   
36.
Wang  Chen  Bao  Chun-Hui  Wu  Wan-Yu  Hsu  Chia-Hsun  Zhao  Ming-Jie  Zhang  Xiao-Ying  Lien  Shui-Yang  Zhu  Wen-Zhang 《Journal of Materials Science》2022,57(26):12341-12355
Journal of Materials Science - Molybdenum oxide (MoOx) films had been grown by using plasma-enhanced atomic layer deposition (PEALD) with Mo(CO)6 precursor and O2 plasma reactant in a substrate...  相似文献   
37.

We discuss the temperature dependence of a common low temperature local thermometer, a tunnel junction between a superconductor and a normal metal (NIS junction). Towards the lowest temperatures its characteristics tend to saturate, which is usually attributed to selfheating effects. In this technical note, we reanalyze this saturation and show that the temperature independent subgap current of the junction alone explains in some cases the low temperature behavior quantitatively.

  相似文献   
38.
Engineering new glass compositions have experienced a sturdy tendency to move forward from (educated) trial-and-error to data- and simulation-driven strategies. In this work, we developed a computer program that combines data-driven predictive models (in this case, neural networks) with a genetic algorithm to design glass compositions with desired combinations of properties. First, we induced predictive models for the glass transition temperature (Tg) using a dataset of 45,302 compositions with 39 different chemical elements, and for the refractive index (nd) using a dataset of 41,225 compositions with 38 different chemical elements. Then, we searched for relevant glass compositions using a genetic algorithm informed by a design trend of glasses having high nd (1.7 or more) and low Tg (500 °C or less). Two candidate compositions suggested by the combined algorithms were selected and produced in the laboratory. These compositions are significantly different from those in the datasets used to induce the predictive models, showing that the used method is indeed capable of exploration. Both glasses met the constraints of the work, which supports the proposed framework. Therefore, this new tool can be immediately used for accelerating the design of new glasses. These results are a stepping stone in the pathway of machine learning-guided design of novel glasses.  相似文献   
39.
Journal of Chemical Ecology - Biocontrol agents such as parasitic wasps use long-range volatiles and host-associated cues from lower trophic levels to find their hosts. However, this chemical...  相似文献   
40.
While protein medications are promising for treatment of cancer and autoimmune diseases, challenges persist in terms of development and injection stability of high-concentration formulations. Here, the extensional flow properties of protein-excipient solutions are examined via dripping-onto-substrate extensional rheology, using a model ovalbumin (OVA) protein and biocompatible excipients polysorbate 20 (PS20) and 80 (PS80). Despite similar PS structures, differences in extensional flow are observed based on PS identity in two regimes: at moderate total concentrations where surface tension differences drive changes in extensional flow behavior, and at small PS:OVA ratios, which impact the onset of weakly elastic flow behavior. Undesirable elasticity is observed in ultra-concentrated formulations, independent of PS identity; higher PS contents are required to observe these effects than in analogous polymeric excipient solutions. These studies reveal novel extensional flow behaviors in protein-excipient solutions, and provide a straightforward methodology for assessing the extensional flow stability of new protein-excipient formulations.  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-23

京公网安备 11010802026262号