全文获取类型
收费全文 | 924篇 |
免费 | 58篇 |
国内免费 | 8篇 |
专业分类
化学 | 673篇 |
晶体学 | 8篇 |
力学 | 28篇 |
数学 | 100篇 |
物理学 | 181篇 |
出版年
2024年 | 2篇 |
2023年 | 3篇 |
2022年 | 23篇 |
2021年 | 34篇 |
2020年 | 17篇 |
2019年 | 23篇 |
2018年 | 18篇 |
2017年 | 14篇 |
2016年 | 35篇 |
2015年 | 28篇 |
2014年 | 40篇 |
2013年 | 56篇 |
2012年 | 68篇 |
2011年 | 80篇 |
2010年 | 64篇 |
2009年 | 50篇 |
2008年 | 63篇 |
2007年 | 49篇 |
2006年 | 32篇 |
2005年 | 39篇 |
2004年 | 35篇 |
2003年 | 31篇 |
2002年 | 37篇 |
2001年 | 20篇 |
2000年 | 14篇 |
1999年 | 9篇 |
1998年 | 10篇 |
1997年 | 8篇 |
1996年 | 7篇 |
1995年 | 8篇 |
1994年 | 7篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 6篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1934年 | 1篇 |
排序方式: 共有990条查询结果,搜索用时 15 毫秒
31.
K.C. Devarayapalli S.V. Prabhakar Vattikuti T.V.M. Sreekanth Ki Soo Yoo P.C. Nagajyothi Jaesool Shim 《应用有机金属化学》2020,34(3):e5376
Herein, cobalt (Co)-based metal–organic zeolitic imidazole frameworks (ZIF-67) coupled with g-C3N4 nanosheets synthesized via a simple microwave irradiation method. SEM, TEM and HR-TEM results showed that ZIF-67 were uniformly dispersed on g-C3N4 surfaces and had a rhombic dodecahedron shape. The photocatalytic properties of g-C3N4/ZIF-67 nanocomposite were evaluated by photocatalytic dye degradation of crystal violet (CV), 4-chlorophenol (4-CP) and photocatalytic hydrogen (H2) production. In presence of visible light illumination, the photocatalytic dye results showed that 95% CV degradation and 53% 4-CP degradation within 80 min. The H2 production of the g-C3N4/ZIF-67 composite was 2084 μmol g−1, which is 3.84 folds greater than that of bare g-C3N4 (541 μmol g−1). 相似文献
32.
Jaehyun Park Seonghan Kim Sangsoo Kim Ki Hyun Nam 《Journal of synchrotron radiation》2018,25(2):323-328
The multifarious injection chamber for molecular structure study (MICOSS) experimental system has been developed at the Pohang Accelerator Laboratory X‐ray Free‐Electron Laser for conducting serial femtosecond crystallography. This system comprises several instruments such as a dedicated sample chamber, sample injectors, sample environment diagnostic system and detector stage for convenient distance manipulation. Serial femtosecond crystallography experiments of lysozyme crystals have been conducted successfully. The diffraction peaks have reached to ~1.8 Å resolution at the photon energy of 9.785 keV. 相似文献
33.
Muhammad Saleem Anser Ali Chang-Shik Choi Bong Joo Park Eun Ha Choi Ki Hwan Lee 《Journal of fluorescence》2014,24(4):995-1001
In recent years, fluorescent probes for the detection of environmentally and biologically important metal cations have received extensive attention for designing and development of fluorescent chemosensors. Herein, we report the photophysical results of 2-(2-fluorobenzoyl)-N-(2-methoxyphenyl) hydrazinecarbothioamide (4) functionalized as Ni (II) sensor in micromolar concentration level. Through fluorescence titration at 488 nm, we were confirmed that ligand 4 showed the remarkable emission by complexation between 4 and Ni (II) while it appeared no emission in case of the competitive ions (Cr3+, Fe2+, Co2+, Ba2+, Cu2+, Ca2+, Na+, K+, Cu+, Cs+). Furthermore, ligand 4 exhibited no toxicity with precise cell permeability toward normal living cells using L929 cell lines in bio imaging experiment investigated through confocal fluorescence microscope. The non-toxic behavior of ligand 4 (assessed by MTT assay) and its ability to track the Ni2+ in living cells suggest its possibility to use in biological system as nickel sensor. Figure
? 相似文献
34.
Lianghui Chen Dechao Niu Cheng Hao Lee Yuan Yao Ki Lui Kin Man Ho Pei Li 《Particle & Particle Systems Characterization》2016,33(10):756-763
A scalable synthesis of magnetic core–shell nanocomposite particles, acting as a novel class of magnetic resonance (MR) contrast agents, has been developed. Each nanocomposite particle consists of a biocompatible chitosan shell and a poly(methyl methacrylate) (PMMA) core where multiple aggregated γ‐Fe2O3 nanoparticles are confined within the hydrophobic core. Properties of the nanocomposite particles including their chemical structure, particle size, size distribution, and morphology, as well as crystallinity of the magnetic nanoparticles and magnetic properties were systematically characterized. Their potential application as an MR contrast agent has been evaluated. Results show that the nanocomposite particles have good stability in biological media and very low cytotoxicity in both L929 mouse fibroblasts (normal cells) and HeLa cells (cervical cancer cells). They also exhibited excellent MR imaging performance with a T2 relaxivity of up to 364 mMFe?1 s?1. An in vivo MR test performed on a naked mouse bearing breast tumor indicates that the nanocomposite particles can localize in both normal liver and tumor tissues. These results suggest that the magnetic core–shell nanocomposite particles are an efficient, inexpensive and safe T2‐weighted MR contrast agent for both liver and tumor MR imaging in cancer therapy. 相似文献
35.
We apply the theory of signature invariants of links in rational homology spheres to covering links of homology boundary links. From patterns and Seifert matrices of homology boundary links, we derive an explicit formula to compute signature invariants of their covering links. Using the formula, we produce fused boundary links that are positive mutants of ribbon links but are not concordant to boundary links. We also show that for any finite collection of patterns, there are homology boundary links that are not concordant to any homology boundary links admitting a pattern in the collection.
36.
Jung-Ah Kang Ji-Sun Kwak Sang-Heon Park Kyu-Young Sim Seul Ki Kim Youngnim Shin In Jung Jung Jeong-In Yang Jang-Soo Chun Sung-Gyoo Park 《Experimental & molecular medicine》2021,53(4):560
Zinc is a trace element that is essential for immune responses. Therefore, changes in cellular zinc levels in specific immune cells may influence inflammatory autoimmune diseases, such as rheumatoid arthritis (RA). However, the regulation of zinc mobilization in immune cells and its role in the pathogenesis of RA are not fully understood. Thus, we investigated the roles of zinc transporters in RA pathogenesis. We demonstrated that ZIP8 was specifically upregulated in CD4+ T cells that infiltrated the inflamed joint and that ZIP8 deficiency in CD4+ T cells abrogated collagen-induced arthritis. ZIP8 deficiency dramatically affected zinc influx in effector T cells and profoundly reduced T cell receptor (TCR)-mediated signaling, including NF-κB and MAPK signaling, which are pathways that are involved in T helper (Th) 17 cell differentiation. Taken together, our findings suggest that ZIP8 depletion in CD4+ T cells attenuates TCR signaling due to insufficient cellular zinc, thereby reducing the function of effector CD4+ T cells, including Th17 cells. Our results also suggest that targeting ZIP8 may be a useful strategy to inhibit RA development and pathogenesis.Subject terms: Autoimmunity, Immunological disorders 相似文献
37.
Eui‐Jun Choi Chang‐Hyeon Kim Jung‐Ki Park 《Journal of Polymer Science.Polymer Physics》1999,37(17):2430-2438
The polycaprolactone (PCL)/starch blends were prepared by using the starch‐g‐PCL (SGCL) graft copolymers as compatibilizers, and their mechanical properties were correlated with the compatibilizing effect of the SGCL copolymers having various molecular structures. The modulus and strength of the PCL/starch blend were decreased, whereas the percent elongation and the toughness were increased remarkably with the addition of SGCL having appropriate graft structure. These property changes were analyzed in terms of the PCL crystallinity and the interfacial adhesion between the PCL matrix and starch dispersion phases, which were dominated by the compatibilizing effects of the SGCL copolymers. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2430–2438, 1999 相似文献
38.
Cyclometalated Palladium(II) N‐Heterocyclic Carbene Complexes: Anticancer Agents for Potent In Vitro Cytotoxicity and In Vivo Tumor Growth Suppression 下载免费PDF全文
Dr. Tommy Tsz‐Him Fong Dr. Chun‐Nam Lok Dr. Clive Yik‐Sham Chung Dr. Yi‐Man Eva Fung Dr. Pui‐Keong Chow Pui‐Ki Wan Prof. Dr. Chi‐Ming Che 《Angewandte Chemie (International ed. in English)》2016,55(39):11935-11939
Palladium(II) complexes are generally reactive toward substitution/reduction, and their biological applications are seldom explored. A new series of palladium(II) N‐heterocyclic carbene (NHC) complexes that are stable in the presence of biological thiols are reported. A representative complex, [Pd(C^N^N)(N,N′‐nBu2NHC)](CF3SO3) ( Pd1 d , HC^N^N=6‐phenyl‐2,2′‐bipyridine, N,N′‐nBu2NHC=N,N′‐di‐n‐butylimidazolylidene), displays potent killing activity toward cancer cell lines (IC50=0.09–0.5 μm ) but is less cytotoxic toward a normal human fibroblast cell line (CCD‐19Lu, IC50=11.8 μm ). In vivo anticancer studies revealed that Pd1 d significantly inhibited tumor growth in a nude mice model. Proteomics data and in vitro biochemical assays reveal that Pd1 d exerts anticancer effects, including inhibition of an epidermal growth factor receptor pathway, induction of mitochondrial dysfunction, and antiangiogenic activity to endothelial cells. 相似文献
39.
Reducible Polyethylenimine Nanoparticles for Efficient siRNA Delivery in Corneal Neovascularization Therapy 下载免费PDF全文
Hyounkoo Han Sohee Son Sejin Son Namho Kim Ji Young Yhee Jae Hyeop Lee Jun‐Sub Choi Choun‐Ki Joo Hohyeon Lee Duhwan Lee Won Jong Kim Sun Hwa Kim Ick Chan Kwon Hyuncheol Kim Kwangmeyung Kim 《Macromolecular bioscience》2016,16(11):1583-1597
The aim of this study is to establish the safe and effective ocular delivery system of therapeutic small interfering RNA (siRNA) in corneal neovascularization therapy. The major hurdle present in siRNA‐based corneal neovascularization (CNV) therapy is severe cytotoxicity caused by repetitive drug treatment. A reducible branched polyethylenimine (rBPEI)‐based nanoparticle (NP) system is utilized as a new siRNA carrier as a hope for CNV therapy. The thiolated BPEI is readily self‐crosslinked in mild conditions to make high molecular weight rBPEI thus allowing the creation of stable siRNA/rBPEI nanoparticles (siRNA‐rBPEI‐NPs). In the therapeutic region, the rBPEI polymeric matrix is effectively degraded into nontoxic LMW BPEI inside the reductive cytosol causing the rapid release of the encapsulated siRNA into the cytosol to carry out its function. The fluorescent‐labeled siRNA‐rBPEI‐NPs can release siRNA into the entire corneal region after subconjuctival injection into the eye of Sprague Dawley rats thus confirming the proof of concept of this system.
40.
Yuen PK 《Lab on a chip》2008,8(8):1374-1378
In this Technical Note, for the first time, a truly "plug-n-play" modular microfluidic system (SmartBuild Plug-n-Play Modular Microfluidic System) is presented for designing and building integrated modular microfluidic systems for biological and chemical applications. The modular microfluidic system can be built by connecting multiple microfluidic components together to form a larger integrated system. The SmartBuild System comprises of a motherboard with interconnect channels/grooves, fitting components, microchannel inserts with different configurations and microchips/modules with different functionalities. Also, heaters, micropumps and valving systems can be designed and used in the system. Examples of an integrated mixing system and reaction systems are presented here to demonstrate the versatility of the SmartBuild System. 相似文献