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   142444篇
  免费   27112篇
  国内免费   13579篇
化学   112841篇
晶体学   1706篇
力学   7656篇
综合类   737篇
数学   14771篇
物理学   45424篇
  2024年   254篇
  2023年   2203篇
  2022年   3123篇
  2021年   4062篇
  2020年   5456篇
  2019年   6454篇
  2018年   4561篇
  2017年   4089篇
  2016年   8250篇
  2015年   8188篇
  2014年   9281篇
  2013年   11835篇
  2012年   12565篇
  2011年   12468篇
  2010年   9622篇
  2009年   9313篇
  2008年   9373篇
  2007年   8230篇
  2006年   7355篇
  2005年   6501篇
  2004年   5071篇
  2003年   4174篇
  2002年   4589篇
  2001年   3556篇
  2000年   3220篇
  1999年   2623篇
  1998年   2041篇
  1997年   1857篇
  1996年   1994篇
  1995年   1605篇
  1994年   1547篇
  1993年   1233篇
  1992年   1124篇
  1991年   1033篇
  1990年   847篇
  1989年   587篇
  1988年   499篇
  1987年   395篇
  1986年   394篇
  1985年   342篇
  1984年   260篇
  1983年   169篇
  1982年   148篇
  1981年   111篇
  1980年   79篇
  1979年   47篇
  1978年   35篇
  1976年   39篇
  1975年   35篇
  1974年   47篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
The design and exploration of efficient, stable and environmentally compatible organic emitters for an electrochemiluminescence (ECL) sensor is a promising topic. Herein, a novel environmentally-friendly luminophore, ZnBCBTP@MWCNTs, were fabricated via self-assembly of porphyrin molecules (ZnBCBTP) onto multi-walled carbon nanotubes (MWCNTs). The resulting luminophore ZnBCBTP@MWCNTs displayed not only the highly ECL property and but also the good accelerated electron mobility. Then, a label-free ECL biosensor based ZnBCBTP@MWCNTs was constructed for the ultrasensitive detection of uric acid. Excitingly, this proposed ECL biosensor performed a good linear relationship in the range of 0–300 μM with a low detection limit of 1.4 μM, thus offering another reliable and feasible sensing platform for clinical bioanalysis with good selectivity, stability, and repeatability.  相似文献   
92.
93.
Cai  Peng  Yue  Xiaokui  Wang  Mingming  Cui  Yao 《Nonlinear dynamics》2022,108(3):2309-2322
Nonlinear Dynamics - A capacitive micromachined ultrasonic transducer (CMUT) due to many benefits is being considered as an imaging and therapeutic technology recently. The critical challenge is to...  相似文献   
94.
Ding  Hao  Wang  Jin-Ting  Lu  Li-Qiao  Pan  Jian-Wen 《Nonlinear dynamics》2021,104(4):3365-3384
Nonlinear Dynamics - Conventional tuned liquid column dampers (TLCDs) are deficient in multidirectionality. In contrast, toroidal TLCDs are designed to extend the application to multidirectional...  相似文献   
95.
Acta Mathematica Sinica, English Series - We are interested in the existence and asymptotic behavior for the least energy solutions of the following fractional eigenvalue problem $$\left({\rm{P}}...  相似文献   
96.
Let L be an additive map between (real or complex) matrix algebras sending n×n Hermitian idempotent matrices to m×m Hermitian idempotent matrices. We show that there are nonnegative integers p,q with n(p+q)=rm and an m×m unitary matrix U such thatL(A)=U[(Ip?A)(Iq?At)0m?r]U?,for any n×n Hermitian A with rational trace. We also extend this result to the (complex) von Neumann algebra setting, and provide a supplement to the Dye-Bunce-Wright Theorem asserting that every additive map of Hermitian idempotents extends to a Jordan ?-homomorphism.  相似文献   
97.
Journal of Radioanalytical and Nuclear Chemistry - In the present work the final products of coumarin radiation chemical transformation are investigated by chromatography. During radiolysis of...  相似文献   
98.
99.
Exosomes are nanovesicles secreted by most cellular types that carry important biochemical compounds throughout the body with different purposes, playing a preponderant role in cellular communication. Because of their structure, physicochemical properties and stability, recent studies are focusing in their use as nanocarriers for different therapeutic compounds for the treatment of different diseases ranging from cancer to Parkinson's disease. However, current bioseparation protocols and methodologies are selected based on the final exosome application or intended use and present both advantages and disadvantages when compared among them. In this context, this review aims to present the most important technologies available for exosome isolation while discussing their advantages and disadvantages and the possibilities of being combined with other strategies. This is critical since the development of novel exosome‐based therapeutic strategies will be constrained to the effectiveness and yield of the selected downstream purification methodologies for which a thorough understanding of the available technological resources is needed.  相似文献   
100.
Journal of Thermal Analysis and Calorimetry - The fire behavior of one flame-retardant PVC cable used as building wire is investigated in this work. Bench scale tests were performed using a cone...  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