全文获取类型
收费全文 | 1465篇 |
免费 | 75篇 |
国内免费 | 7篇 |
专业分类
化学 | 1170篇 |
晶体学 | 7篇 |
力学 | 16篇 |
数学 | 170篇 |
物理学 | 184篇 |
出版年
2023年 | 16篇 |
2022年 | 38篇 |
2021年 | 42篇 |
2020年 | 49篇 |
2019年 | 34篇 |
2018年 | 17篇 |
2017年 | 25篇 |
2016年 | 51篇 |
2015年 | 54篇 |
2014年 | 46篇 |
2013年 | 74篇 |
2012年 | 94篇 |
2011年 | 121篇 |
2010年 | 57篇 |
2009年 | 49篇 |
2008年 | 96篇 |
2007年 | 108篇 |
2006年 | 86篇 |
2005年 | 89篇 |
2004年 | 60篇 |
2003年 | 66篇 |
2002年 | 68篇 |
2001年 | 13篇 |
2000年 | 13篇 |
1999年 | 5篇 |
1998年 | 12篇 |
1997年 | 7篇 |
1996年 | 34篇 |
1995年 | 22篇 |
1994年 | 17篇 |
1993年 | 11篇 |
1992年 | 16篇 |
1991年 | 4篇 |
1990年 | 6篇 |
1989年 | 3篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1985年 | 6篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1973年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有1547条查询结果,搜索用时 15 毫秒
981.
Cazares LH Troyer DA Wang B Drake RR Semmes OJ 《Analytical and bioanalytical chemistry》2011,401(1):17-27
Matrix-assisted laser desorption ionization (MALDI) imaging mass spectrometry (IMS) is a powerful tool for the generation
of multidimensional spatial expression maps of biomolecules directly from a tissue section. From a clinical proteomics perspective,
this method correlates molecular detail to histopathological changes found in patient-derived tissues, enhancing the ability
to identify candidates for disease biomarkers. The unbiased analysis and spatial mapping of a variety of molecules directly
from clinical tissue sections can be achieved through this method. Conversely, targeted IMS, by the incorporation of laser-reactive
molecular tags onto antibodies, aptamers, and other affinity molecules, enables analysis of specific molecules or a class
of molecules. In addition to exploring tissue during biomarker discovery, the integration of MALDI-IMS methods into existing
clinical pathology laboratory practices could prove beneficial to diagnostics. Querying tissue for the expression of specific
biomarkers in a biopsy is a critical component in clinical decision-making and such markers are a major goal of translational
research. An important challenge in cancer diagnostics will be to assay multiple parameters in a single slide when tissue
quantities are limited. The development of multiplexed assays that maximize the yield of information from a small biopsy will
help meet a critical challenge to current biomarker research. This review focuses on the use of MALDI-IMS in biomarker discovery
and its potential as a clinical diagnostic tool with specific reference to our application of this technology to prostate
cancer. 相似文献
982.
Tongdeesoontorn W Mauer LJ Wongruong S Sriburi P Rachtanapun P 《Chemistry Central journal》2011,5(1):6
Background
Cassava starch, the economically important agricultural commodity in Thailand, can readily be cast into films. However, the cassava starch film is brittle and weak, leading to inadequate mechanical properties. The properties of starch film can be improved by adding plasticizers and blending with the other biopolymers. 相似文献983.
Grubel K Laughlin BJ Maltais TR Smith RC Arif AM Berreau LM 《Chemical communications (Cambridge, England)》2011,47(37):10431-10433
Exposure of 3-hydroxyflavonolate complexes of the group 12 metals to UV light under aerobic conditions results in oxidative carbon-carbon bond cleavage and CO release. This reactivity is novel in that it occurs under mild reaction conditions and suggests that light-induced CO-release reactivity involving metal flavonolate species may be possible in biological systems. 相似文献
984.
985.
Mario Frahm Thorsten von Drathen Lisa Marie Gronbach Alice Voss Felix Lorenz Jonas Bresien Alexander Villinger Frank Hoffmann Prof. Dr. Malte Brasholz 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(30):12550-12554
Tetrahydrocarbazoles and perhydrocyclohepta[b]indoles undergo a catalytic cascade singlet oxygenation in alkaline medium, which leads to chiral tricyclic perhydropyrido- and perhydroazepino[1,2-a]indoles in a single operation. These photooxygenation products are new synthetic equivalents of uncommon C,N-diacyliminium ions and can be functionalized with the aid of phosphoric acid organocatalysis. 相似文献
986.
Gregory B. Kharas Lisa M. Gennett Yolondria L. Harvey Elizabeth R. Jennings Denny Petropoulos Ovie C. Smith 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(3):163-167
Novel trisubstituted ethylenes, chlorine ring-substituted 2-cyano-3-phenyl-2-propenamides, RC6H3CH?C(CN)CONH2 (where R is 2,3-dichloro, 2,4-dichloro, 2,6-dichloro, 3,4-dichloro, 2-chloro-5-nitro, 4-chloro-3-nitro, 5-chloro-2-nitro) were synthesized by potassium hydroxide catalyzed Knoevenagel condensation of ring-substituted benzaldehydes and cyanoacetamide and characterized by CHN elemental analysis, IR, 1H- and 13C-NMR. Novel copolymers of the ethylenes and styrene were prepared at equimolar monomer feed composition by solution in the presence of a radical initiation (AIBN) at 70°C. The composition of the copolymers was calculated from nitrogen analysis, and the structures were analyzed by IR, 1H- and 13C-NMR, GPC, DSC, and TGA. Thus, the order of relative reactivity (1/r1) and the tendency toward alternation of monomer units in the copolymer for the monomers is 2-Cl-5-NO2 (3.09) > 5-Cl-2-NO2 (1.88) > 4-Cl-3-NO2 (0.97) > 2,6-Cl2 (0.93) > 3,4-Cl2 (0.31) > 2,4-Cl2 (0.30) > 2,3-Cl2 (0.22). High Tg of the copolymers in comparison with that of polystyrene indicates a substantial decrease in chain mobility of the copolymer due to the high dipolar character of the trisubstituted ethylene monomer unit. Decomposition of the copolymers in nitrogen occurred in two steps, first in the 200–500°C range with residue (3.5–5.0 wt%), which then decomposed in the 500–800°C range. 相似文献
987.
988.
Lisa C. Shriver-Lake Joel Golden Laura Bracaglia Frances S. Ligler 《Analytical and bioanalytical chemistry》2013,405(16):5611-5614
Bacterial infection and intoxication can present with common symptoms. The ability to identify a bacteria or toxin rapidly in clinical samples is critical for administering the appropriate treatment. The microflow cytometer has previously demonstrated the ability to test for six bacteria and toxins simultaneously in buffer. In this study, the number of bacteria and toxins analyzed was increased to ten, positive and negative controls were incorporated in all assays, and most importantly, multiplexed immunoassays were demonstrated in clinical matrices. The multiplexed assays using the microflow cytometer demonstrated detection limits similar to or better than other reported antibody-based methods for pathogen detection (ELISA, lateral flow, array biosensors). In most cases, detection from complex clinical matrices (serum and nasal wash) achieved limits of detection equivalent to those for spiked buffer samples. Clinical samples spiked with bacteria and/or toxins were also analyzed successfully in blind trials. 相似文献
989.
990.
We study the phase diagram of two-flavor QCD at imaginary chemical potentials in the chiral limit. To this end we compute order parameters for chiral symmetry breaking and quark confinement. The interrelation of quark confinement and chiral symmetry breaking is analyzed with a new order parameter for the confinement phase transition. We show that it is directly related to both the quark density as well as the Polyakov loop expectation value. Our analytical and numerical results suggest a close relation between the chiral and the confinement phase transition. 相似文献