全文获取类型
收费全文 | 544145篇 |
免费 | 5480篇 |
国内免费 | 1371篇 |
专业分类
化学 | 280132篇 |
晶体学 | 7733篇 |
力学 | 26342篇 |
综合类 | 17篇 |
数学 | 70550篇 |
物理学 | 166222篇 |
出版年
2021年 | 5263篇 |
2020年 | 5799篇 |
2019年 | 6561篇 |
2018年 | 8624篇 |
2017年 | 8773篇 |
2016年 | 12149篇 |
2015年 | 6657篇 |
2014年 | 11003篇 |
2013年 | 24395篇 |
2012年 | 19280篇 |
2011年 | 22822篇 |
2010年 | 17071篇 |
2009年 | 16872篇 |
2008年 | 21547篇 |
2007年 | 21366篇 |
2006年 | 19407篇 |
2005年 | 17352篇 |
2004年 | 16118篇 |
2003年 | 14469篇 |
2002年 | 14348篇 |
2001年 | 14973篇 |
2000年 | 11587篇 |
1999年 | 8983篇 |
1998年 | 7815篇 |
1997年 | 7668篇 |
1996年 | 7152篇 |
1995年 | 6472篇 |
1994年 | 6454篇 |
1993年 | 6205篇 |
1992年 | 6552篇 |
1991年 | 7014篇 |
1990年 | 6720篇 |
1989年 | 6637篇 |
1988年 | 6444篇 |
1987年 | 6233篇 |
1986年 | 5968篇 |
1985年 | 7555篇 |
1984年 | 7891篇 |
1983年 | 6640篇 |
1982年 | 6941篇 |
1981年 | 6460篇 |
1980年 | 6115篇 |
1979年 | 6616篇 |
1978年 | 6872篇 |
1977年 | 6724篇 |
1976年 | 6664篇 |
1975年 | 6401篇 |
1974年 | 6205篇 |
1973年 | 6481篇 |
1972年 | 4757篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Crystallography Reports - Methods of coherent X-ray diffraction imaging of the spatial structure of noncrystalline objects and nanocrystals (nanostructures) are considered. Particular attention is... 相似文献
82.
Satyanarayana A. V. S. Rao M. Jagannadha Mouli K. Chandra 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(3):1509-1513
Journal of Radioanalytical and Nuclear Chemistry - 相似文献
83.
Russian Physics Journal - The paper shows that the values of zero-point energy and vibrations of atoms in a crystal determined by the uncertainty principle, depend on the dynamic response of atoms.... 相似文献
84.
Journal of Applied and Industrial Mathematics - We study the problem of optimal location of the ambulance fleet at the base stations. The objective is to minimize the average waiting time for... 相似文献
85.
Tomáš Hložek Martin Štícha Miroslava Bursová Ivan Jelínek Petr Tůma Radomír Čabala 《Electrophoresis》2020,41(18-19):1564-1567
Riociguat is novel antihypertensive drug for treatment of pulmonary hypertension. As such, it is still being tested in many clinical and pharmacokinetic trials. Existing methods that determine serum riociguat and desmethylriociguat (DMR) are based solely on liquid chromatography with mass spectrometry. Therefore, we present a novel capillary electrophoresis with mass spectrometry method (CE-MS) for their determination in human serum as alternative method for ongoing trials. Complete resolution of both analytes was achieved by means of pH optimization of ammonium formate background electrolytes that are fully compatible with ESI/MS detection. Simple liquid-liquid extraction was used as sample pretreatment. The calibration dependence of the method was linear (in the range of 10–1000 ng/mL), with adequate accuracy (90.1–114.9%) and precision (13.4%). LOD and LOQ were arbitrarily set at 10 ng/mL for both analytes. Clinical applicability was validated using serum samples from patients treated with riociguat in pharmacokinetic study and the results corresponded with reference HPLC-MS/MS values. Capillary electrophoresis proved to be sensitive and selective tool for the analysis of riociguat and DMR. 相似文献
86.
87.
88.
Paired single residue‐transposed Lys‐N and Lys‐C digestions for label‐free identification of N‐terminal and C‐terminal MS/MS peptide product ions: ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry and tandem mass spectrometry for peptide de novo sequencing 下载免费PDF全文
89.
The influence of different referencing methods on the accuracy of δ13C value measurement of ethanol fuel by gas chromatography/combustion/isotope ratio mass spectrometry 下载免费PDF全文
90.
ABSTRACTThe Coupled-Cluster (CC) theory is one of the most successful high precision methods used to solve the stationary Schrödinger equation. In this article, we address the mathematical foundation of this theory with focus on the advances made in the past decade. Rather than solely relying on spectral gap assumptions (non-degeneracy of the ground state), we highlight the importance of coercivity assumptions – Gårding type inequalities – for the local uniqueness of the CC solution. Based on local strong monotonicity, different sufficient conditions for a local unique solution are suggested. One of the criteria assumes the relative smallness of the total cluster amplitudes (after possibly removing the single amplitudes) compared to the Gårding constants. In the extended CC theory the Lagrange multipliers are wave function parameters and, by means of the bivariational principle, we here derive a connection between the exact cluster amplitudes and the Lagrange multipliers. This relation might prove useful when determining the quality of a CC solution. Furthermore, the use of an Aubin–Nitsche duality type method in different CC approaches is discussed and contrasted with the bivariational principle. 相似文献