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991.
Srivastava Anshu Garg Gaurav Sharma Poojadevi Shah Nancy Sharma Sonal Shrivastava Neeta 《平面色谱法杂志一现代薄层色谱法》2016,29(3):203-208
JPC – Journal of Planar Chromatography – Modern TLC - Bacopa monnieri (L.) Pennell, commonly known as Brahmi, is an important medicinal plant of the Ayurvedic System of Medicine and is... 相似文献
992.
Uday P. Palukuru Arash HanifiCushla M. McGoverin Sean DevlinPeter I. Lelkes Nancy Pleshko 《Analytica chimica acta》2016
Disease or injury to articular cartilage results in loss of extracellular matrix components which can lead to the development of osteoarthritis (OA). To better understand the process of disease development, there is a need for evaluation of changes in cartilage composition without the requirement of extensive sample preparation. Near infrared (NIR) spectroscopy is a chemical investigative technique based on molecular vibrations that is increasingly used as an assessment tool for studying cartilage composition. However, the assignment of specific molecular vibrations to absorbance bands in the NIR spectrum of cartilage, which arise from overtones and combinations of primary absorbances in the mid infrared (MIR) spectral region, has been challenging. In contrast, MIR spectroscopic assessment of cartilage is well-established, with many studies validating the assignment of specific bands present in MIR spectra to specific molecular vibrations. In the current study, NIR imaging spectroscopic data were obtained for compositional analysis of tissues that served as an in vitro model of OA. MIR spectroscopic data obtained from the identical tissue regions were used as the gold-standard for collagen and proteoglycan (PG) content. MIR spectroscopy in transmittance mode typically requires a much shorter pathlength through the sample (≤10 microns thick) compared to NIR spectroscopy (millimeters). Thus, this study first addressed the linearity of small absorbance bands in the MIR region with increasing tissue thickness, suitable for obtaining a signal in both the MIR and NIR regions. It was found that the linearity of specific, small MIR absorbance bands attributable to the collagen and PG components of cartilage (at 1336 and 856 cm−1, respectively) are maintained through a thickness of 60 μm, which was also suitable for NIR data collection. MIR and NIR spectral data were then collected from 60 μm thick samples of cartilage degraded with chondroitinase ABC as a model of OA. Partial least squares (PLS) regression using NIR spectra as input predicted the MIR-determined compositional parameters of PG/collagen within 6% of actual values. These results indicate that NIR spectral data can be used to assess molecular changes that occur with cartilage degradation, and further, the data provide a foundation for future clinical studies where NIR fiber optic probes can be used to assess the progression of cartilage degradation. 相似文献
993.
Frontispiece: Judicious Ligand Design in Ruthenium Polypyridyl CO2 Reduction Catalysts to Enhance Reactivity by Steric and Electronic Effects 下载免费PDF全文
994.
Cover Picture: Absolute Configuration from Different Multifragmentation Pathways in Light‐Induced Coulomb Explosion Imaging (ChemPhysChem 16/2016) 下载免费PDF全文
Dr. Martin Pitzer Gregor Kastirke Dr. Maksim Kunitski Dr. Till Jahnke Dr. Tobias Bauer Christoph Goihl Florian Trinter Carl Schober Kevin Henrichs Jasper Becht Stefan Zeller Helena Gassert Markus Waitz Andreas Kuhlins Hendrik Sann Felix Sturm Florian Wiegandt Dr. Robert Wallauer Dr. Lothar Ph. H. Schmidt Allan S. Johnson Manuel Mazenauer Benjamin Spenger Sabrina Marquardt Sebastian Marquardt Prof. Dr. Horst Schmidt‐Böcking Prof. Dr. Jürgen Stohner Prof. Dr. Reinhard Dörner Dr. Markus Schöffler Prof. Dr. Robert Berger 《Chemphyschem》2016,17(16):2448-2448
995.
Nancy Sarahy Gaytn-Barrientos David Morales-Morales Dea Herrera-Ruiz Reyna Reyes-Martínez Jesús Rivera-Islas 《Acta Crystallographica. Section C, Structural Chemistry》2016,72(4):280-284
Dapsone, formerly used to treat leprosy, now has wider therapeutic applications. As is the case for many therapeutic agents, low aqueous solubility and high toxicity are the main problems associated with its use. Derivatization of its amino groups has been widely explored but shows no significant therapeutic improvements. Cocrystals have been prepared to understand not only its structural properties, but also its solubility and dissolution rate. Few salts of dapsone have been described. The title salts, C12H13N2O2S+·C6H5O3S−·H2O and C12H13N2O2S+·CH3SO3−·H2O, crystallize as hydrates and both compounds exhibit the same space group (monoclinic, P21/n). The asymmetric unit of each salt consists of a 4‐[(4‐aminophenyl)sulfonyl]anilinium monocation, the corresponding sulfonate anion and a water molecule. The cation, anion and water molecule form hydrogen‐bonded networks through N—H…O=S, N—H…Owater and Owater—H…O=S hydrogen bonds. For both salts, the water molecules interact with one sulfonate anion and two anilinium cations. The benzenesulfonate salt forms a two‐dimensional network, while the hydrogen bonding within the methanesulfonate salt results in a three‐dimensional network. 相似文献
996.
Assessing the Impact of a Statewide STEM Investment on K–12, Higher Education,and Business/Community STEM Awareness Over Time 下载免费PDF全文
Toni A. Sondergeld Carla C. Johnson Janet B. Walten 《School science and mathematics》2016,116(2):104-110
Despite monetary and educational investments in science, technology, engineering, and mathematics (STEM) being at record high levels, little attention has been devoted to generating a common understanding of STEM. In addition, working with business, K–12 schools, and/or institutions of higher education to establish a grassroots effort to help community members understand the importance of STEM regarding the future prosperity of the United States in general, and specifically the preparedness of children for careers of now and the future, has been nonexistent. The purpose of our study is to assess the impact of a statewide STEM professional development program implemented for two years on STEM awareness over time among various community stakeholders (i.e., K–12 teachers, higher education faculty, and business members). STEM awareness and beliefs about STEM engagement, resources, student preparation, and careers all improved over time for all groups. However, business members had the greatest growth over time and held significantly higher awareness compared with the other groups in most areas. Our findings suggest that a statewide STEM partnership/network model is a viable option for growing collective impact and sustainability of STEM K–12 education. 相似文献
997.
The task of generating a nonredundant set of low-energy conformations for small molecules is of fundamental importance for many molecular modeling and drug-design methodologies. Several approaches to conformer generation have been published. Exhaustive searches suffer from the exponential growth of the search space with increasing degrees of conformational freedom (number of rotatable bonds). Stochastic algorithms do not suffer as much from the exponential increase of search space and provide a good coverage of the energy minima. Here, the use of a multiobjective genetic algorithm in the generation of conformer ensembles is investigated. Distance geometry is used to generate an initial conformer, which is then subject to geometric modifications encoded by the individuals of the genetic algorithm. The geometric modifications apply to torsion angles about rotatable bonds, stereochemistry of double bonds and tetrahedral chiral centers, and ring conformations. The geometric diversity of the evolving conformer ensemble is preserved by a fitness-sharing mechanism based on the root-mean-square distance of the atomic coordinates. Molecular symmetry is taken into account in the distance calculation. The geometric modifications introduce strain into the structures. The strain is relaxed using an MMFF94-like force field in a postprocessing step that also removes conformational duplicates and structures whose strain energy remains above a predefined window from the minimum energy value found in the set. The implementation, called Balloon, is available free of charge on the Internet ( http://www.abo.fi/~mivainio/balloon/). 相似文献
998.
999.
Ma Y Luciani T Porter RA Russell AT Johnson D Marston G 《Physical chemistry chemical physics : PCCP》2007,9(37):5084-5087
The mechanism of formation of pinonic and norpinonic acids from alpha-pinene ozonolysis has been investigated by studying the products of the ozonolysis of an enone derived from alpha-pinene using gas chromatography coupled to mass spectrometry. 相似文献
1000.