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   3331篇
  免费   33篇
  国内免费   9篇
文化教育   3373篇
  2023年   14篇
  2022年   34篇
  2021年   57篇
  2020年   112篇
  2019年   143篇
  2018年   172篇
  2017年   161篇
  2016年   154篇
  2015年   108篇
  2014年   141篇
  2013年   841篇
  2012年   108篇
  2011年   99篇
  2010年   101篇
  2009年   86篇
  2008年   94篇
  2007年   86篇
  2006年   76篇
  2005年   43篇
  2004年   44篇
  2003年   51篇
  2002年   38篇
  2001年   45篇
  2000年   39篇
  1999年   33篇
  1998年   24篇
  1997年   26篇
  1996年   21篇
  1995年   24篇
  1994年   15篇
  1993年   23篇
  1992年   18篇
  1991年   28篇
  1990年   14篇
  1989年   29篇
  1988年   18篇
  1987年   27篇
  1986年   15篇
  1985年   25篇
  1984年   15篇
  1983年   17篇
  1982年   18篇
  1981年   14篇
  1980年   13篇
  1979年   15篇
  1978年   12篇
  1975年   7篇
  1974年   6篇
  1973年   7篇
  1971年   7篇
排序方式: 共有3373条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Industry advocates argue that by tailoring services and commercial solicitations to match media users’ personal interests, data-driven marketing benefits both consumers and businesses. This article shows, however, that advertisers and marketers who are taking up ideas and techniques from behavioral economics tell their clients a very different story about the aims and use of digital marketing and consumer surveillance. Listening in on this discourse demonstrates that some digital marketers conceptualize their own practices as forms of social control, appropriating concepts from behavioral economics to identify consumers’ cognitive and affective biases and target their vulnerabilities. Behavioral economics recognizes that economic decisions are not simply dictated by rational self-interest; rather, such choices depend on cognitive heuristics and habits, and can be manipulated through the design of “choice architecture.” This article discusses implications of the behavioral turn in data-driven marketing for critical advertising scholars, public advocates, and regulators.  相似文献   
5.
ObjectivePrimary tumor treatment through surgical resection and adjuvant therapy has been extensively studied, but there is a lack of effective strategies and drugs for the treatment of tumor metastases. Here, we describe a functional product based on a combination of compounds, which can be used as an adjuvant therapy and has well-known mechanisms for inhibiting cancer metastases, improving anti-cancer treatment, and enhancing immunity and antioxidant capacity. Our designed combination, named MVBL, consists of four inexpensive compounds: L-selenium-methylselenocysteine (MSC), D-‍α‍-tocopheryl succinic acid (VES), β‍-carotene (β‍-Ca), and L-lysine (Lys).MethodsThe effects of MVBL on cell viability, cell cycle, cell apoptosis, cell migration, cell invasion, reactive oxygen species (ROS), and paclitaxel (PTX)-combined treatment were studied in vitro. The inhibition of tumor metastasis, antioxidation, and immune enhancement capacity of MVBL were determined in vivo.ResultsMVBL exhibited higher toxicity to tumor cells than to normal cells. It did not significantly affect the cell cycle of cancer cells, but increased their apoptosis. Wound healing, adhesion, and transwell assays showed that MVBL significantly inhibited tumor cell migration, adhesion, and invasion. MVBL sensitized MDA-MB-231 breast cancer cells to PTX, indicating that it can be used as an adjuvant to enhance the therapeutic effect of chemotherapy drugs. In mice, experimental data showed that MVBL inhibited tumor metastasis, prolonged their survival time, and enhanced their antioxidant capacity and immune function.ConclusionsThis study revealed the roles of MVBL in improving immunity and antioxidation, preventing tumor growth, and inhibiting metastasis in vitro and in vivo. MVBL may be used as an adjuvant drug in cancer therapy for improving the survival and quality of life of cancer patients.  相似文献   
6.
7.
8.
9.
国产十种乌头的染色体研究   总被引:1,自引:0,他引:1  
本文描述了我国产毛茛科乌头属的10个种的染色体数目和形态。  根据该属染色体基 数为8(x=8),可将这些种归为二倍体、四倍体、六倍体和八倍体种。  10种乌头的染色体在数目、大小、结构上表现出相关性。其中具根状茎而多年生的种多为二倍体,染色体形态较大,第3-7号多为近端着丝点(st)染色体, 具块茎而二年生的种多为多倍体,染色体形态较小,第3-7号多为近中着丝点(sm)染色体。染色体演化方向可能是二倍体→多倍体、大→ 小、st→sm。这进一步证明根状茎种较块茎种原始。根据染色体数目和形态,又可将这些种的染色体分为两类。这进一步支持了目前分类学上的牛扁亚属和乌头亚属的划分。本文还讨论了这些种的有关分类问题。  相似文献   
10.
In this paper, we propose a new language model, namely, a dependency structure language model, for topic detection and tracking (TDT) to compensate for weakness of unigram and bigram language models. The dependency structure language model is based on the Chow expansion theory and the dependency parse tree generated by a linguistic parser. So, long-distance dependencies can be naturally captured by the dependency structure language model. We carried out extensive experiments to verify the proposed model on topic tracking and link detection in TDT. In both cases, the dependency structure language models perform better than strong baseline approaches.  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