全文获取类型
收费全文 | 1523篇 |
免费 | 29篇 |
国内免费 | 5篇 |
专业分类
化学 | 946篇 |
晶体学 | 8篇 |
力学 | 48篇 |
数学 | 333篇 |
物理学 | 222篇 |
出版年
2019年 | 7篇 |
2017年 | 13篇 |
2016年 | 29篇 |
2015年 | 22篇 |
2014年 | 23篇 |
2013年 | 66篇 |
2012年 | 60篇 |
2011年 | 80篇 |
2010年 | 53篇 |
2009年 | 33篇 |
2008年 | 53篇 |
2007年 | 73篇 |
2006年 | 56篇 |
2005年 | 59篇 |
2004年 | 52篇 |
2003年 | 34篇 |
2002年 | 27篇 |
2001年 | 18篇 |
2000年 | 10篇 |
1999年 | 9篇 |
1998年 | 14篇 |
1997年 | 13篇 |
1996年 | 32篇 |
1995年 | 31篇 |
1994年 | 35篇 |
1993年 | 28篇 |
1992年 | 21篇 |
1991年 | 18篇 |
1990年 | 26篇 |
1989年 | 17篇 |
1988年 | 13篇 |
1987年 | 16篇 |
1986年 | 13篇 |
1985年 | 26篇 |
1984年 | 29篇 |
1983年 | 12篇 |
1982年 | 34篇 |
1981年 | 23篇 |
1980年 | 16篇 |
1979年 | 19篇 |
1978年 | 37篇 |
1977年 | 20篇 |
1976年 | 22篇 |
1975年 | 16篇 |
1974年 | 14篇 |
1973年 | 14篇 |
1972年 | 8篇 |
1971年 | 11篇 |
1970年 | 9篇 |
1964年 | 9篇 |
排序方式: 共有1557条查询结果,搜索用时 31 毫秒
1.
2.
Multiple orthogonal polynomials generalize standard orthogonal polynomials by requiring orthogonality with respect to several inner products. This paper discusses an application to the approximation of matrix functions and presents quadrature rules that generalize the anti-Gauss rules proposed by Laurie. 相似文献
3.
4.
Locked by Design: A Conformationally Constrained Transglutaminase Tag Enables Efficient Site‐Specific Conjugation 下载免费PDF全文
Dr. Vanessa Siegmund Dr. Stefan Schmelz Stephan Dickgiesser Jan Beck Aileen Ebenig Heiko Fittler Dr. Holm Frauendorf Dr. Birgit Piater Dr. Ulrich A. K. Betz Dr. Olga Avrutina Dr. Andrea Scrima Prof. Dr. Hans‐Lothar Fuchsbauer Prof. Dr. Harald Kolmar 《Angewandte Chemie (International ed. in English)》2015,54(45):13420-13424
Based on the crystal structure of a natural protein substrate for microbial transglutaminase, an enzyme that catalyzes protein crosslinking, a recognition motif for site‐specific conjugation was rationally designed. Conformationally locked by an intramolecular disulfide bond, this structural mimic of a native conjugation site ensured efficient conjugation of a reporter cargo to the therapeutic monoclonal antibody cetuximab without erosion of its binding properties. 相似文献
5.
Novel Osmium‐based Coordination Complexes as Photosensitizers for Panchromatic Photodynamic Therapy 下载免费PDF全文
Savo Lazic Pavel Kaspler Ge Shi Susan Monro Tariq Sainuddin Sarah Forward Kamola Kasimova Robie Hennigar Arkady Mandel Sherri McFarland Lothar Lilge 《Photochemistry and photobiology》2017,93(5):1248-1258
Cancer remains a major global malaise requiring the advent of new, efficient and low‐cost treatments. Photodynamic therapy, which combines a photosensitizer and photons to produce cytotoxic reactive oxygen species, has been established as an effective cancer treatment but has yet to become mainstream. One of the main limitations has been the paucity of photosensitizers that are effective over a wide range of wavelengths, can exert their cytotoxic effects in hypoxia, are easily synthesized and produce few if any side effects. To address these shortfalls, three new osmium‐based photosensitizers (TLD1822, TLD1824 and TLD1829) were synthesized and their photophysical and photobiological attributes determined. These photosensitizers are panchromatic (i.e. black absorbers), activatable from 200 to 900 nm and have strong resistance to photobleaching. In vitro studies show photodynamic therapy efficacy with both red and near‐infrared light in normoxic and hypoxic conditions, which translated to good in vivo efficacy of TLD1829 in a subcutaneous murine colon cancer model. 相似文献
6.
Effect of SIMS ionization probability on depth resolution for organic/inorganic interfaces 下载免费PDF全文
Nicholas J. Popczun Lars Breuer Andreas Wucher Nicholas Winograd 《Surface and interface analysis : SIA》2017,49(10):933-939
Secondary ion mass spectrometry (SIMS) relies on the fact that surface particles ejected from a solid surface are ionized under ion bombardment. By comparing the signal of molecular secondary ions desorbed from an organic film with that of the corresponding sputtered neutral precursor molecules, we investigate the variation of the molecular ionization probability when depth profiling through the film to the substrate interface. As a result, we find notable variations of the ionization probability both at the original surface and in the interface region, leading to a strong distortion of the measured SIMS depth profile. The experiments show that the effect can act in two ways, leading either to an apparent broadening or to an artificial sharpening of the observed film‐substrate transition. As a consequence, we conclude that care must be taken when assessing interface location, width, or depth resolution from a molecular SIMS depth profile. 相似文献
7.
Sandra Grebenteuch Clemens Kanzler Stefan Klaußnitzer Lothar W. Kroh Sascha Rohn 《Molecules (Basel, Switzerland)》2021,26(4)
Lipid oxidation and the resulting volatile organic compounds are the main reasons for a loss of food quality. In addition to typical compounds, such as alkanes, aldehydes and alcohols, methyl ketones like heptan-2-one, are repeatedly described as aroma-active substances in various foods. However, it is not yet clear from which precursors methyl ketones are formed and what influence amino compounds have on the formation mechanism. In this study, the formation of methyl ketones in selected food-relevant fats and oils, as well as in model systems with linoleic acid or pure secondary degradation products (alka-2,4-dienals, alken-2-als, hexanal, and 2-butyloct-2-enal), has been investigated. Elevated temperatures were chosen for simulating processing conditions such as baking, frying, or deep-frying. Up to seven methyl ketones in milk fat, vegetable oils, and selected model systems have been determined using static headspace gas chromatography-mass spectrometry (GC-MS). This study showed that methyl ketones are tertiary lipid oxidation products, as they are derived from secondary degradation products such as deca-2,4-dienal and oct-2-enal. The study further showed that the position of the double bond in the precursor compound determines the chain length of the methyl ketone and that amino compounds promote the formation of methyl ketones to a different degree. These compounds influence the profile of the products formed. As food naturally contains lipids as well as amino compounds, the proposed pathways are relevant for the formation of aroma-active methyl ketones in food. 相似文献
8.
A homogeneous, isotropic cylinder in an equilibrium state of plane strain, whose cross-section is a rectangle R : [0 < y
1 < 2L; 0 < y
2 < h] with h/L 1, is considered. There are no body forces and the long sides are stress free. At y
1 = 0 and y
1 = 2L, there are arbitrary loadings, each statically equivalent to a uniformly distributed tensile or compressive stress c. Within the theory of nonlinear elasticity and with the strains and strain gradients assumed to be sufficiently small (but with no such assumptions on the displacement gradients), it is proved that if (,=1,2) represents the Cauchy stress tensor and the Kronecker delta, then |–c11| decays exponentially to zero in R with distance from the nearer end, and the decay constant depends only upon the material but is independent of L. 相似文献
9.
K. S. Breuer 《Experiments in fluids》1995,19(2):138-141
The calibration of high-bandwidth sensors is typically carried out in an steady environment or at least a well-controlled unsteady flow. A simple technique for calibration of sensors in flow fields with arbitrary unsteadiness (such as a turbulent field) is described. Although the method requires a DC reference measurement at each calibration point, the resulting calibration is accurate for both average and unsteady measurements up to the full bandwidth of the sensor. Applications and limitations of the technique are also discussed.This work is supported by AFOSR grant F49620-93-1-0194, monitored by Dr. J. McMichael and ONR grant N00014-92-J-1918, monitored by Dr. L.P. Purtel. The author gratefully acknowledges helpful discussions with Olivier Piepsz, Ruben Rathnasingham and Bill George. 相似文献
10.