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   84322篇
  免费   510篇
  国内免费   379篇
化学   27453篇
晶体学   910篇
力学   6863篇
数学   33076篇
物理学   16909篇
  2021年   111篇
  2020年   96篇
  2019年   114篇
  2018年   10531篇
  2017年   10358篇
  2016年   6253篇
  2015年   1021篇
  2014年   522篇
  2013年   868篇
  2012年   4064篇
  2011年   10821篇
  2010年   5898篇
  2009年   6254篇
  2008年   6788篇
  2007年   8936篇
  2006年   370篇
  2005年   1427篇
  2004年   1650篇
  2003年   2067篇
  2002年   1114篇
  2001年   322篇
  2000年   379篇
  1999年   240篇
  1998年   271篇
  1997年   217篇
  1996年   277篇
  1995年   185篇
  1994年   139篇
  1993年   163篇
  1992年   114篇
  1991年   124篇
  1990年   119篇
  1989年   126篇
  1988年   113篇
  1987年   136篇
  1986年   107篇
  1985年   125篇
  1984年   122篇
  1983年   111篇
  1982年   116篇
  1981年   118篇
  1980年   106篇
  1979年   122篇
  1978年   95篇
  1977年   73篇
  1976年   92篇
  1975年   82篇
  1974年   74篇
  1973年   75篇
  1966年   69篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Karakuş  Erman  Erdemir  Eda  Suna  Garen  Liv  Lokman  Gunduz  Simay  Can  Şevval Arzu 《Journal of fluorescence》2021,31(6):1617-1625
Journal of Fluorescence - We have constructed a novel fluorescein-based fluorescent chemosensor, FL-In, functionalised with an indole moiety and capable of sensing by both the optical...  相似文献   
2.
Central European Journal of Operations Research - Digital competences are among the most important competences in modern society, with the education system playing a key role in the acquisition of...  相似文献   
3.
Riociguat is novel antihypertensive drug for treatment of pulmonary hypertension. As such, it is still being tested in many clinical and pharmacokinetic trials. Existing methods that determine serum riociguat and desmethylriociguat (DMR) are based solely on liquid chromatography with mass spectrometry. Therefore, we present a novel capillary electrophoresis with mass spectrometry method (CE-MS) for their determination in human serum as alternative method for ongoing trials. Complete resolution of both analytes was achieved by means of pH optimization of ammonium formate background electrolytes that are fully compatible with ESI/MS detection. Simple liquid-liquid extraction was used as sample pretreatment. The calibration dependence of the method was linear (in the range of 10–1000 ng/mL), with adequate accuracy (90.1–114.9%) and precision (13.4%). LOD and LOQ were arbitrarily set at 10 ng/mL for both analytes. Clinical applicability was validated using serum samples from patients treated with riociguat in pharmacokinetic study and the results corresponded with reference HPLC-MS/MS values. Capillary electrophoresis proved to be sensitive and selective tool for the analysis of riociguat and DMR.  相似文献   
4.
In the paper, the authors establish several integral representations for the generating functions of the large and little Schröder numbers and for the large and little Schröder numbers.  相似文献   
5.
Mesoscopic modeling at the pore scale offers great promise in exploring the underlying structure transport performance of flow through porous media. The present work studies the fluid flow subjected to capillarity-induced resonance in porous media characterized by different porous structure and wettability. The effects of porosity and wettability on the displacement behavior of the fluid flow through porous media are discussed. The results are presented in the form of temporal evolution of percentage saturation and displacement of the fluid front through porous media. The present study reveals that the vibration in the form of acoustic excitation could be significant in the mobilization of fluid through the porous media. The dependence of displacement of the fluid on physicochemical parameters like wettability of the surface, frequency along with the porosity is analyzed. It was observed that the mean displacement of the fluid is more in the case of invading fluid with wetting phase where the driving force strength is not so dominant.  相似文献   
6.
7.
We prove that the group of diffeomorphisms of the interval [0, 1] contains surface groups whose action on (0, 1) has no global fix point and such that only countably many points of the interval (0, 1) have non-trivial stabiliser.  相似文献   
8.
9.
Journal of Sol-Gel Science and Technology - Multifunctional magnetic mesoporous nanocomposites are promising materials to remove the various pollutants from water due to the remarkable properties...  相似文献   
10.
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