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   74篇
  免费   1篇
  国内免费   14篇
化学   45篇
晶体学   1篇
力学   1篇
数学   19篇
物理学   23篇
  2023年   1篇
  2022年   1篇
  2021年   1篇
  2020年   3篇
  2019年   5篇
  2018年   2篇
  2017年   3篇
  2016年   6篇
  2015年   3篇
  2014年   1篇
  2013年   13篇
  2012年   2篇
  2011年   5篇
  2010年   4篇
  2009年   5篇
  2008年   7篇
  2007年   7篇
  2006年   4篇
  2005年   1篇
  2003年   1篇
  2002年   1篇
  2001年   2篇
  2000年   2篇
  1999年   1篇
  1998年   1篇
  1997年   2篇
  1996年   1篇
  1994年   2篇
  1992年   2篇
排序方式: 共有89条查询结果,搜索用时 15 毫秒
1.
 A laboratory information management system (LIMS) can make a major contribution to the quality and therefore to the efficiency and competitiveness of a laboratory. Since it can impact all aspects of a laboratory's organization it must be the key if not the principal player of the laboratory's quality system. It should support the laboratory in establishing, maintaining and applying quality procedures thereby enabling the laboratory to achieve its quality goals. As a tool, LIMS permits the laboratory to input and use its own know-how and experience to optimize the total organization (internal and external) and workflow of generated information. However, perceived "quality" in the context of an LIMS, can be viewed as being made up of different facets such as the security, reliability and accessibility of information as well as its turn around time and production cost. This paper reviews the role of a LIMS in the laboratory and the contribution that both system design and functionality can have on "building quality ". Received: 5 October 1998 · Accepted: 20 October 1998  相似文献   
2.
Bi2S3/g-C3N4 (BSCN) samples with different mass ratios of CN to BS were prepared by a facile and practicable hydrothermal method with 2D g-C3N4 nanosheets (CN). The microscopic morphology and structure of pure CN, BS and BSCN were measured by multiple testing methods. Analysis results show that the BSCN was prepared successfully, and the Bi2S3 nanoparticles closely and uniformly adhered to the surface of CN with sheet-like structure. The introduction of Bi2S3 did not change the structure of the CN. The results of the ultraviolet–visible spectroscopic analysis, photoluminescence spectra and electrochemical performance indicated that BSCN showed superior visible-light response compared with CN, and the separation and transfer efficiency of photogenerated carriers was significantly improved. With the decrease of mass ratio of CN/BS, the photocatalytic activity of BSCN initially increased and then decreased for 20 ppm of Rhodamine B solution (RhB), and the Bi2S3/g-C3N4-B with a mass ratio of 8:1 for CN to BS showed optimal photocatalytic performance (98.98%). Furthermore, the Bi2S3/g-C3N4-B exhibited apparent degradation effects (1.021 x10-2, 0.879 x10-2 and 0.793 x10-2 min?1) to three kinds of antibiotics (tetracycline, ciprofloxacin, and oxytetracycline). The BSCN samples still maintained higher degradation efficiency after five cycles of degradation to tetracycline. The capture experiments and the electron spin resonance (ESR) spectra analysis indicated that the h+ and ·O2? played a major role, and ·OH played secondary role during the photocatalytic reaction.  相似文献   
3.
Dual magnetic resonant modes at neighboring frequencies are induced in a split double-ring metamaterial, which contribute to a transparency window within a broad stopband. This resonance-based window exhibits a favorable filtering performance due to its fast roll-off characteristic, and a considerable sensitivity to refractive index changes of the surrounding medium.  相似文献   
4.
殷跃平 《力学学报》2007,15(5):718-720
生态环境脆弱区工程地质研究是工程地质学科必须面对的一个重要领域。作者指出,工程地质学应当夯实学科基础,吸取相关学科理论,重塑工程地质理论与实践,出精品工程,重视人才培养。  相似文献   
5.
In spite of its low isotopic abundance in methane (about 5×10−4), CH3D contributes greatly to the very weak absorption in the 1.58 μm methane transparency window. This methane window deserves to be characterized in details because it is important for planetary applications in particular for Titan and the giant planets. In this work, we recorded the CH3D spectrum by high sensitivity differential absorption spectroscopy (αmin≈5×10−8 cm−1) both at room temperature and at 81 K. A list of more than 9000 lines was constructed from the 81 K spectrum for the 6099–6530 cm−1 region. In order to get the temperature dependence of the line intensities, the low energy values have to be determined. The rovibrational assignments available in the literature provide low energy values for about 380 strong transitions of the region. This is insufficient to characterize the temperature dependence of the CH3D absorption between 6200 and 6400 cm−1. In this interval, a list of 5500 lines was constructed from the room temperature spectrum. The empirical energy values of the transitions were derived from the ratio of the intensities at 81 K and 294 K. The exact and empirical lower state energies included in the final line lists provided as Supplementary Material, allow for accounting for the temperature dependence of the CH3D spectrum in the entire 6099–6530 cm−1 region.Our measurements have been compared to the spectroscopic parameters and assignments available in the literature in particular those adopted in the HITRAN database. Improvements and corrections are proposed for the wavenumber calibration and for some lower state energies.  相似文献   
6.
大学化学课程的混合式教学实施与探索   总被引:1,自引:0,他引:1  
为更好地建设精品资源共享课,提高人才培养质量,结合哈尔滨工业大学"大学化学国家精品课程"现有改革成果,初步尝试了面授加视频的混合式教学,探讨了在实践过程中取得效果和反映出的问题,并为混合式教学的推广实施提出了建议。旨在促进未来大学化学课程的在线教育发展,提高教学效果。  相似文献   
7.
以含异丙基和三氟甲基结构二胺单体3,3′-二异丙基-4,4′-二胺基苯基-4″-三氟甲基甲苯(PATFT)与萘-1,4-二甲酸、间苯二甲酸和4,4-二苯醚二甲酸3种二酸通过膦酰化反应制备一系列新型可溶性聚酰胺,其相对分子量在3.8×104~9.6×104之间.结果表明,该聚合物具有优异的溶解性能,常温不仅能溶解于N-甲基吡咯烷酮(NMP)、N,N-二甲基乙酰胺(DMAc)、N,N-二甲基甲酰胺(DMF)等高沸点有机溶剂,在加热条件下甚至能较好的溶解在四氢呋喃、氯仿、二氯甲烷等低沸点溶剂中;突出的光学性能,截止波长范围在322~350 nm,80%的透过率波长范围为378~403 nm;良好的热学性能,玻璃化转变温度(Tg)范围在213~220?C,氮气氛围下5%和10%热失重温度范围分别为453~458?C和470~482?C.聚合物薄膜具有优异的机械性能,拉伸强度、杨氏模量、断裂伸长率分别对应为68~97 MPa,1.9~2.9 GPa,14.8%~16.7%.广角X-射线图谱表明聚合物为无定形态结构.  相似文献   
8.
方洪锦 《数学杂志》1994,14(3):335-338
在这篇文章里,我们证明了,当环S是R的excellent扩张,M是S-模时,M做为S-模的弱维数与M做为R-模的弱维数相等。  相似文献   
9.
Let T be a complete local (Noetherian) ring with maximal ideal M, P a nonmaximal ideal of T, and C = {Q 1, Q 2,…} a (nonempty) finite or countable set of nonmaximal prime ideals of T. Let {p 1, p 2,…} be a set of nonzero regular elements of T, whose cardinality is the same as that of C. Suppose that p i  ∈ Q j if and only if i = j. We give conditions that ensure there is an excellent local unique factorization domain A such that A is a subring of T, the maximal ideal of A is MA, the (MA)-adic completion of A is T, and so that the following three conditions hold: (1) p i  ∈ A for every i; (2) AP = (0), and if J is a prime ideal of T with JA = (0), then J ? P or J ? Q i for some i; (3) for each i, p i A is a prime ideal of A, Q i A = p i A, and if J is a prime ideal of T with J ? Q i , then JA ≠ p i A.  相似文献   
10.
《代数通讯》2013,41(5):1321-1336
Abstract

Let (T, M) be a complete local normal integral domain containing the rationals such that |T/M | ≥ c where c is the cardinality of the real numbers. Let p be a non-maximal prime ideal of T such that T p is a regular local ring. We construct a local Unique Factorization Domain (UFD) A such that the M-adic completion of A is T, p is maximal in the generic formal fiber and all fibers of A are geometrically regular except for those over some height one prime ideals.

  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