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   12646篇
  免费   1024篇
  国内免费   9篇
  13679篇
  2023年   51篇
  2022年   99篇
  2021年   233篇
  2020年   134篇
  2019年   201篇
  2018年   238篇
  2017年   218篇
  2016年   313篇
  2015年   607篇
  2014年   636篇
  2013年   771篇
  2012年   1052篇
  2011年   1013篇
  2010年   634篇
  2009年   580篇
  2008年   816篇
  2007年   841篇
  2006年   721篇
  2005年   717篇
  2004年   679篇
  2003年   630篇
  2002年   636篇
  2001年   117篇
  2000年   77篇
  1999年   126篇
  1998年   153篇
  1997年   125篇
  1996年   113篇
  1995年   115篇
  1994年   98篇
  1993年   75篇
  1992年   87篇
  1991年   57篇
  1990年   60篇
  1989年   65篇
  1988年   34篇
  1987年   39篇
  1986年   41篇
  1985年   44篇
  1984年   52篇
  1983年   38篇
  1982年   59篇
  1981年   40篇
  1980年   45篇
  1979年   31篇
  1978年   32篇
  1977年   32篇
  1976年   18篇
  1975年   17篇
  1973年   12篇
排序方式: 共有10000条查询结果,搜索用时 7 毫秒
141.

This paper reports on a systematic study of the plasmonic properties of periodic arrays of gold cylindrical nanoparticles in contact with a gold thin film. Depending on the gold film thickness, it observes several plasmon bands. Using a simple analytical model, it is able to assign all these modes and determine that they are due to the coupling of the grating diffraction orders with the propagating surface plasmons travelling along the film. With finite difference time domain (FDTD) simulations, it demonstrates that large field enhancement occurs at the surface of the nanocylinders due to the resonant excitation of these modes. By tilting the sample, it also observes the evolution of the spectral position of these modes and their tuning through nearly the whole visible range is possible. Such plasmonic substrates combining both advantages of the propagative and localised surface plasmons could have large applications in enhanced spectroscopies.

  相似文献   
142.
Journal of Physiology and Biochemistry - Connections between the midbrain dorsolateral periaqueductal grey (dlPAG) and the pontine A5 region have been shown. The stimulation of both regions evokes...  相似文献   
143.
Mammalian Genome - Intracellular calcium is critical in orchestrating neuronal excitability and analgesia. Carbonic anhydrase-8 (CA8) regulates intracellular calcium signaling through allosteric...  相似文献   
144.
Virtual reality is a powerful tool with the ability to immerse a user within a completely external environment. This immersion is particularly useful when visualizing and analyzing interactions between small organic molecules, molecular inorganic complexes, and biomolecular systems such as redox proteins and enzymes. A common tool used in the biomedical community to analyze such interactions is the Adaptive Poisson‐Boltzmann Solver (APBS) software, which was developed to solve the equations of continuum electrostatics for large biomolecular assemblages. Numerous applications exist for using APBS in the biomedical community including analysis of protein ligand interactions and APBS has enjoyed widespread adoption throughout the biomedical community. Currently, typical use of the full APBS toolset is completed via the command line followed by visualization using a variety of two‐dimensional external molecular visualization software. This process has inherent limitations: visualization of three‐dimensional objects using a two‐dimensional interface masks important information within the depth component. Herein, we have developed a single application, UnityMol‐APBS, that provides a dual experience where users can utilize the full range of the APBS toolset, without the use of a command line interface, by use of a simple graphical user interface (GUI) for either a standard desktop or immersive virtual reality experience.  相似文献   
145.
146.
Movement of Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) and lake sturgeon (A. fulvescens) in the St. Lawrence Estuary (Québec, Canada) are not fully understood. To assess the movement extent of both species, a mark–recapture study was conducted in collaboration with commercial fishermen operating in the St. Lawrence Estuary. Between 1981 and 2015, 3,367 Atlantic sturgeon (fork length 21.8–199.5 cm) and 3,180 lake sturgeon (fork length 17.8–190.8 cm) were tagged and released. Of these, 673 Atlantic sturgeon and 42 lake sturgeon were recaptured. The maximum distances traveled between capture and recapture locations were 1,307 km for Atlantic sturgeon (8 years after initial capture) and 252 km for lake sturgeon (less than 1 year after initial capture). Statistical analyses identified differences in the dispersal distance of both species as revealed by a first component characterized by individuals with short dispersal distances (98% and <35 km for Atlantic sturgeon; 58% and <1 km for lake sturgeon) and a second component characterized by individuals with longer dispersal distances (2% and >600 km for Atlantic sturgeon; 42% and >190 km for lake sturgeon). We suggest that the short dispersal distances detected in the vast majority of Atlantic sturgeon recaptures likely reflect strong site fidelity, highlighting the importance of the St. Lawrence Estuary as a preferred habitat for juveniles and subadults. Although recaptures were low for lake sturgeon because this species is only marginally targeted by commercial fishermen in the St. Lawrence Estuary, our results also showed that this species uses estuarine habitats and that half of the population seems to exhibit strong site fidelity (67% of individuals were recaptured within 2 km).  相似文献   
147.
148.
149.
150.
Abstract

Studies on the genus Peyssonnelia (Rhodophyceae). X. Presence of Peyssonnelia codana (Rosenvinge) Denizot in the Mediterranean.—Peyssonnelia codana (Rosenvinge) Denizot, previously known only from Denmark, is recorded from the vicinity of a thermal power plant outlet (Martigues-Ponteau, Gulf of Fos, France). Mediterranean specimens are described and new details about the morphology of sporangial and sexual nemathecia are given.  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