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   6286篇
  免费   906篇
  国内免费   942篇
化学   4852篇
晶体学   64篇
力学   307篇
综合类   77篇
数学   851篇
物理学   1983篇
  2024年   5篇
  2023年   121篇
  2022年   105篇
  2021年   170篇
  2020年   252篇
  2019年   261篇
  2018年   195篇
  2017年   189篇
  2016年   270篇
  2015年   278篇
  2014年   276篇
  2013年   464篇
  2012年   452篇
  2011年   467篇
  2010年   354篇
  2009年   348篇
  2008年   401篇
  2007年   340篇
  2006年   318篇
  2005年   320篇
  2004年   310篇
  2003年   273篇
  2002年   284篇
  2001年   261篇
  2000年   189篇
  1999年   164篇
  1998年   127篇
  1997年   114篇
  1996年   110篇
  1995年   96篇
  1994年   94篇
  1993年   74篇
  1992年   83篇
  1991年   59篇
  1990年   56篇
  1989年   43篇
  1988年   51篇
  1987年   29篇
  1986年   26篇
  1985年   28篇
  1984年   19篇
  1983年   6篇
  1982年   11篇
  1981年   11篇
  1980年   8篇
  1979年   5篇
  1973年   3篇
  1972年   2篇
  1969年   2篇
  1967年   2篇
排序方式: 共有8134条查询结果,搜索用时 187 毫秒
1.
2.
Mao  Jin-Chao  Hong  Jin-Jing  Lin  Ming-Zheng  Han  Feng  Li  Dong 《Journal of fluorescence》2021,31(4):1169-1176
Journal of Fluorescence - A new Zn(II)-bearing metal-organic framework (MOF), namely, {[Zn2(L)2(H2O)]·8H2O·DMF}n (1) has been generated via applying...  相似文献   
3.
The first alkali-metal vanadium iodate fluoride, CsVO2F(IO3), with a novel 3D anionic framework, has been rationally designed and hydrothermally synthesized. The 3D [VO2F(IO3)] framework in CsVO2F(IO3) is built from 0D Λ-shaped cis-[VO3F(IO3)2]4− polyanions via corner-sharing of oxo anions and bridging of the iodate groups. CsVO2F(IO3) displays both a strong second-harmonic generation (SHG) 1.1 times as strong as KTiOPO4 (KTP) under 2.05 μm laser radiation and high laser-induced damage threshold (LIDT) of 107.9 MW cm−2. This work provides a new route to design SHG crystals with stable 3D anionic structures from low-dimensional structural building units.  相似文献   
4.
5.
Conductive hydrogels with ionic compounds possess great potential for the development of soft smart devices. A dielectric scarfskin is typically required for these devices to prevent short circuiting, leading to devices with lower stretchability than the hydrogel. Henceforth, commonly used dielectric materials, such as PDMS and Ecoflex, cannot be largely stretched. Hydrogel devices with ultrastretchability are required to accommodate hostile application environments. Herein, we propose a hydrogel fiber coated with a dielectric layer that can be stretched to over 2000% of its initial length. The fiber remains conductive when stretched to ~1300%. In addition, the core/sheath hydrogel fiber can be endowed with a variety of functional properties, such as electroluminescence (EL), photoluminescence (PL), and magnetic‐responsiveness, demonstrating scalability of the resultant fiber. The present work can pave the way for numerous next‐generation soft devices, such as smart textiles and wearable electronics. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 272–280  相似文献   
6.
Han  Peigeng  Zhang  Xue  Mao  Xin  Yang  Bin  Yang  Songqiu  Feng  Zhaochi  Wei  Donghui  Deng  Weiqiao  Pullerits  Tõnu  Han  Keli 《中国科学:化学(英文版)》2019,62(10):1405-1413
Lead-free halide double perovskites have gathered wide scientific interest since they are environmentally friendly and stable.However,compared to the lead perovskites,their optoelectronic properties are compromised.Herein we report a series of bulk lead-free mixed Bi-In halide double perovskites:Cs_2AgBi_(1-x)In_xCl_6(0x1).The Cs_2AgBi_(0.125)In_(0.875)Cl_6breaks the parity-forbidden transition and retains direct band gap structure,having warm-white light emission,with photoluminescence quantum efficiency(PLQE)of 70.3%,much higher than the PLQE of reported lead perovskite materials.Its exciton self-trapping dynamics is investigated.Meanwhile,the Cs_2AgBi_(0.125)In_(0.875)Cl_6nanocrystals and Cs_2AgBi_(0.125)In_(0.875)Cl_6microcrystals can be synthesized by modified hot injection and rapid cooling crystallization,respectively.The size effect of Cs_2AgBi_(0.125)In_(0.875)Cl_6is studied on the photoluminescence(PL)property.Additionally,the bulk material exhibits excellent stability on exposure to light,humidity and air for more than 3 months.It is a promising candidate as highly efficient warm white-light emitting material for road lighting.  相似文献   
7.
In this paper, we introduce and study differential graded(DG for short) polynomial algebras. In brief, a DG polynomial algebra A is a connected cochain DG algebra such that its underlying graded algebra A~# is a polynomial algebra K[x_1, x_2,..., x_n] with |xi| = 1 for any i ∈ {1, 2,..., n}. We describe all possible differential structures on DG polynomial algebras, compute their DG automorphism groups, study their isomorphism problems, and show that they are all homologically smooth and Gorenstein DG algebras. Furthermore, it is proved that the DG polynomial algebra A is a Calabi-Yau DG algebra when its differential ?_A≠ 0 and the trivial DG polynomial algebra(A, 0) is Calabi-Yau if and only if n is an odd integer.  相似文献   
8.
Fan  Shuhua  Wang  Yongli  Wang  Xian 《Crystallography Reports》2018,63(3):428-432

The swine major histocompatibility complex (MHC) class I molecules are also called swine leukocyte antigen (SLA), and most of the highly polymorphic SLA genes are associated with swine diseases. However, the well documented structural reports on swine MHC I molecules remain quite limited. In order to clarify the structural characteristics of the Chinese heishan wild boar MHC class I molecule, SLA-3*0202 and swine β2-microglobulin (sβ2m) with a KMNTQFTAV nonapeptide derived from Influenza A virus Hemagglutinin protein (IAV-HA) were assembled and crystallized. The crystal diffracted at 1.55 Å resolution and belonged to the sp. gr. C121, with the unit-cell parameters a = 206.46 Å, b = 41.47 Å, c = 106.74 Å. The Matthews coefficient and solvent content were calculated to be 2.30 Å3 Da–1 and 46.64%, respectively. The availability of the structure, which is being solved by molecular replacement, will provide new insights into swine MHC I presenting IAV peptides.

  相似文献   
9.
A unique nickel/organic photoredox co-catalyzed asymmetric reductive cross-coupling between α-chloro esters and aryl iodides is developed. This cross-electrophile coupling reaction employs an organic reductant (Hantzsch ester), whereas most reductive cross-coupling reactions use stoichiometric metals. A diverse array of valuable α-aryl esters is formed under these conditions with high enantioselectivities (up to 94 %) and good yields (up to 88 %). α-Aryl esters represent an important family of nonsteroidal anti-inflammatory drugs. This novel synergistic strategy expands the scope of Ni-catalyzed reductive asymmetric cross-coupling reactions.  相似文献   
10.
The use of intact cells in medical research offers a number of advantages over employing cell-free systems. In diagnostics, cells isolated from liquid biopsies can be directly used, speeding up the time of analysis and diminishing the risk of protein degradation by sample manipulation. In drug discovery, studies in live cells take into account aspects neglected in cell-free systems, such as uptake, metabolization, and subcellular concentration by compartmentalization of potential drug candidates. Therefore, probes for studies in cellulo are of paramount importance. Acid ceramidase (AC) is a lysosomal enzyme that hydrolyses ceramides into sphingoid bases and fatty acids. The essential role of this enzyme in the outburst and progress of several diseases, some of them still incurable, is well sustained. Despite the great clinical relevance of AC as a biomarker and therapeutic target, the specific monitoring of AC activity in live cells has remained elusive due to the concomitant existence of neutral and alkaline ceramidases. In this work, we report that 1-deoxydihydroceramides are exclusively hydrolysed by AC. Using N-octanoyl-18-azidodeoxysphinganine as a probe and a BODIPY-substituted bicyclononyne, we show the click-reliant predominant staining of lysosomes, with extra-lysosomal labeling also occurring in some cells. Importantly, using pharmacological and genetic tools together with high resolution mass spectrometry, we demonstrate that both lysosomal and extra-lysosomal staining are AC-dependent. These findings are translated into the specific flow cytometry monitoring of AC activity in intact cells, which fills an important gap in the field of diseases linked to altered AC activity.

The use of intact cells in medical research offers a number of advantages over employing cell-free systems.  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