全文获取类型
收费全文 | 463794篇 |
免费 | 4823篇 |
国内免费 | 1431篇 |
专业分类
化学 | 248238篇 |
晶体学 | 7114篇 |
力学 | 20469篇 |
综合类 | 11篇 |
数学 | 54104篇 |
物理学 | 140112篇 |
出版年
2020年 | 3546篇 |
2019年 | 3991篇 |
2018年 | 5135篇 |
2017年 | 5053篇 |
2016年 | 7656篇 |
2015年 | 4881篇 |
2014年 | 7524篇 |
2013年 | 20070篇 |
2012年 | 14790篇 |
2011年 | 18178篇 |
2010年 | 12535篇 |
2009年 | 12192篇 |
2008年 | 16641篇 |
2007年 | 16910篇 |
2006年 | 15637篇 |
2005年 | 14382篇 |
2004年 | 13023篇 |
2003年 | 11689篇 |
2002年 | 11640篇 |
2001年 | 12928篇 |
2000年 | 9867篇 |
1999年 | 7724篇 |
1998年 | 6670篇 |
1997年 | 6645篇 |
1996年 | 6254篇 |
1995年 | 5813篇 |
1994年 | 5810篇 |
1993年 | 5620篇 |
1992年 | 6256篇 |
1991年 | 6251篇 |
1990年 | 6021篇 |
1989年 | 5925篇 |
1988年 | 6064篇 |
1987年 | 5869篇 |
1986年 | 5598篇 |
1985年 | 7505篇 |
1984年 | 7957篇 |
1983年 | 6614篇 |
1982年 | 7004篇 |
1981年 | 6869篇 |
1980年 | 6743篇 |
1979年 | 6749篇 |
1978年 | 7161篇 |
1977年 | 7034篇 |
1976年 | 7239篇 |
1975年 | 6604篇 |
1974年 | 6753篇 |
1973年 | 7196篇 |
1972年 | 4772篇 |
1971年 | 3863篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
Low-flow chromatography has a rich history of innovation but has yet to reach widespread implementation in bioanalytical applications. Improvements in pump technology, microfluidic connections, and nano-electrospray sources for MS have laid the groundwork for broader application, and innovation in this space has accelerated in recent years. This article reviews the instrumentation used for nano-flow LC, the types of columns employed, and strategies for multidimensionality of separations, which are key to the future state of the technique to the high-throughput needs of modern bioanalysis. An update of the current applications where nano-LC is widely used, such as proteomics and metabolomics, is discussed. But the trend toward biopharmaceutical development of increasingly complex, targeted, and potent therapeutics for the safe treatment of disease drives the need for ultimate selectivity and sensitivity of our analytical platforms for targeted quantitation in a regulated space. The selectivity needs are best addressed by mass spectrometric detection, especially at high resolutions, and exquisite sensitivity is provided by nano-electrospray ionization as the technology continues to evolve into an accessible, robust, and easy-to-use platform. 相似文献
22.
Siberian Mathematical Journal - Let $ \{(A_{i},B_{i})\}_{i=1}^{m} $ be a set pair system. Füredi, Gyárfás, and Király called it $ 1 $ -cross intersecting if $... 相似文献
23.
Edward G. Sheetz Zhao Zhang Alyssa Marogil Minwei Che Dr. Maren Pink Dr. Veronica Carta Prof. Dr. Krishnan Raghavachari Prof. Dr. Amar H. Flood 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(60):e202201584
The recognition of boron compounds is well developed as boronic acids but untapped as organotrifluoroborate anions (R−BF3−). We are exploring the development of these and other designer anions as anion-recognition motifs by considering them as substituted versions of the parent inorganic ion. To this end, we demonstrate strong and reliable binding of organic trifluoroborates, R−BF3−, by cyanostar macrocycles that are size-complementary to the inorganic BF4− progenitors. We find that recognition is modulated by the substituent's sterics and that the affinities are retained using the common K+ salts of R−BF3− anions. 相似文献
24.
25.
Acta Mathematica Hungarica - Minkowski’s classical existence theorem provides necessary and sufficient conditions for a Borel measure on the unit sphere of Euclidean space to be the surface... 相似文献
26.
M. Amar D. Andreucci R. Gianni C. Timofte 《Journal of Mathematical Analysis and Applications》2021,493(2):124533
We prove a well-posedness result for two pseudo-parabolic problems, which can be seen as two models for the same electrical conduction phenomenon in heterogeneous media, neglecting the magnetic field. One of the problems is the concentration limit of the other one, when the thickness of the dielectric inclusions goes to zero. The concentrated problem involves a transmission condition through interfaces, which is mediated by a suitable Laplace-Beltrami type equation. 相似文献
27.
Zadeba E. A. Khokhlov S. S. Kokoulin R. P. Petrukhin A. A. Shulzhenko I. A. Yashin I. I. 《Physics of Atomic Nuclei》2022,85(1):86-91
Physics of Atomic Nuclei - The muon puzzle is an excess of muon bundles generated by primary cosmic rays (PCR) at energies above 10 $${}^{17}$$ eV compared to estimations that assume even a heavy... 相似文献
28.
Clemens G. Raab Georg Regensburger Jamal Hossein Poor 《Journal of Pure and Applied Algebra》2021,225(5):106564
A formal computation proving a new operator identity from known ones is, in principle, restricted by domains and codomains of linear operators involved, since not any two operators can be added or composed. Algebraically, identities can be modelled by noncommutative polynomials and such a formal computation proves that the polynomial corresponding to the new identity lies in the ideal generated by the polynomials corresponding to the known identities. In order to prove an operator identity, however, just proving membership of the polynomial in the ideal is not enough, since the ring of noncommutative polynomials ignores domains and codomains. We show that it suffices to additionally verify compatibility of this polynomial and of the generators of the ideal with the labelled quiver that encodes which polynomials can be realized as linear operators. Then, for every consistent representation of such a quiver in a linear category, there exists a computation in the category that proves the corresponding instance of the identity. Moreover, by assigning the same label to several edges of the quiver, the algebraic framework developed allows to model different versions of an operator by the same indeterminate in the noncommutative polynomials. 相似文献
29.
Kuz’mina L. G. Navasardyan M. A. Kalle P. Bezzubov S. I. 《Crystallography Reports》2021,66(3):420-423
Crystallography Reports - The crystal and molecular structures of Cl–C6H4–O–C16H33 (I) have been studied, and its differential scanning calorimetry (DSC) study is performed.... 相似文献
30.
Nonlinear Dynamics - In this article, the authors simulate and study dark and bright soliton solutions of 1D and 2D regularized long wave (RLW) models. The RLW model occurred in various fields such... 相似文献