全文获取类型
收费全文 | 31524篇 |
免费 | 5051篇 |
国内免费 | 3728篇 |
专业分类
化学 | 16790篇 |
晶体学 | 345篇 |
力学 | 1302篇 |
综合类 | 180篇 |
数学 | 2729篇 |
物理学 | 8497篇 |
无线电 | 10460篇 |
出版年
2024年 | 141篇 |
2023年 | 808篇 |
2022年 | 1094篇 |
2021年 | 1209篇 |
2020年 | 1192篇 |
2019年 | 1180篇 |
2018年 | 980篇 |
2017年 | 1025篇 |
2016年 | 1344篇 |
2015年 | 1577篇 |
2014年 | 1906篇 |
2013年 | 2369篇 |
2012年 | 2818篇 |
2011年 | 2894篇 |
2010年 | 2053篇 |
2009年 | 2017篇 |
2008年 | 2100篇 |
2007年 | 1948篇 |
2006年 | 1707篇 |
2005年 | 1451篇 |
2004年 | 1157篇 |
2003年 | 933篇 |
2002年 | 867篇 |
2001年 | 745篇 |
2000年 | 615篇 |
1999年 | 603篇 |
1998年 | 469篇 |
1997年 | 388篇 |
1996年 | 416篇 |
1995年 | 367篇 |
1994年 | 364篇 |
1993年 | 264篇 |
1992年 | 230篇 |
1991年 | 210篇 |
1990年 | 193篇 |
1989年 | 142篇 |
1988年 | 89篇 |
1987年 | 73篇 |
1986年 | 78篇 |
1985年 | 57篇 |
1984年 | 48篇 |
1983年 | 38篇 |
1982年 | 20篇 |
1981年 | 21篇 |
1980年 | 10篇 |
1979年 | 14篇 |
1978年 | 7篇 |
1977年 | 8篇 |
1976年 | 11篇 |
1975年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
We study the full counting statistics of transport electrons through a semiconductor two-level quantum dot with Rashba spin–orbit (SO) coupling, which acts as a nonabelian gauge field and thus induces the electron transition between two levels along with the spin flip. By means of the quantum master equation approach, shot noise and skewness are obtained at finite temperature with two-body Coulomb interaction. We particularly demonstrate the crucial effect of SO coupling on the super-Poissonian fluctuation of transport electrons, in terms of which the SO coupling can be probed by the zero-frequency cumulants. While the charge currents are not sensitive to the SO coupling. 相似文献
3.
Analysis and pharmacokinetic study of polyphyllin H in beagle dog plasma after oral administration of Rhizoma Paridis Extracts by LC‐MS/MS 下载免费PDF全文
4.
Qin Yin Shou-Guo Wang Xiao-Wei Liang De-Wei Gao Jun Zheng Shu-Li You 《Chemical science》2015,6(7):4179-4183
An organocatalytic asymmetric chlorinative dearomatization of naphthols was realized for the first time, providing chiral naphthalenones with a Cl-containing all-substituted stereocenter in excellent yields and enantioselectivity (up to 97% yield and 96% ee). The reaction features mild reaction conditions, good tolerance of diverse functional groups and simple reaction operation. 相似文献
5.
The Effect of the Spacer of Bis(biurea) Ligands on the Structure of A2L3‐type (A=anion) Phosphate Complexes 下载免费PDF全文
Prof. Biao Wu Dr. Shaoguang Li Prof. Yibo Lei Prof. Huaiming Hu Dr. Nader de Sousa Amadeu Prof. Dr. Christoph Janiak Dr. Jennifer S. Mathieson Dr. De‐Liang Long Prof. Leroy Cronin Prof. Xiao‐Juan Yang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(6):2588-2593
By tuning the length and rigidity of the spacer of bis(biurea) ligands L, three structural motifs of the A2L3 complexes (A represents anion, here orthophosphate PO43?), namely helicate, mesocate, and mono‐bridged motif, have been assembled by coordination of the ligand to phosphate anion. Crystal structure analysis indicated that in the three complexes, each of the phosphate ions is coordinated by twelve hydrogen bonds from six surrounding urea groups. The anion coordination properties in solution have also been studied. The results further demonstrate the coordination behavior of phosphate ion, which shows strong tendency for coordination saturation and geometrical preference, thus allowing for the assembly of novel anion coordination‐based structures as in transition‐metal complexes. 相似文献
6.
7.
This study is concerned with a new,explicit approach by means of which forms of the large strain elastic potential for multiaxial rubberlike elasticity may be obtained based on data for a single deformation mode.As a departure from usual studies,here for the first time errors may be estimated and rendered minimal for all possible deformation modes and,furthermore,failure behavior may be incorporated.Numerical examples presented are in accurate agreement with Treloar's well-known data. 相似文献
8.
Simultaneous quantitative determination of 20 active components in the traditional Chinese medicine formula Zhi‐Zi‐Da‐Huang decoction by liquid chromatography coupled with mass spectrometry: application to study the chemical composition variations in different combinations 下载免费PDF全文
Zheng Tang Ran Yin Kaishun Bi Heyun Zhu Fei Han Kelin Chen Fenrong Wang 《Biomedical chromatography : BMC》2015,29(9):1406-1414
9.
Dr. Jun Zeng Dr. Zhichao Wang Dr. Xin Huang Dr. Sabine S. Eckstein Prof. Dr. Xiaohui Lin Prof. Dr. Hailong Piao Prof. Dr. Cora Weigert Dr. Peiyuan Yin Prof. Dr. Rainer Lehmann Prof. Dr. Guowang Xu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(21):5427-5432
Mass spectrometry (MS) driven metabolomics is a frequently used tool in various areas of life sciences; however, the analysis of polar metabolites is less commonly included. In general, metabolomic analyses lead to the detection of the total amount of all covered metabolites. This is currently a major limitation with respect to metabolites showing high turnover rates, but no changes in their concentration. Such metabolites and pathways could be crucial metabolic nodes (e.g., potential drug targets in cancer metabolism). A stable-isotope tracing capillary electrophoresis–mass spectrometry (CE-MS) metabolomic approach was developed to cover both polar metabolites and isotopologues in a non-targeted way. An in-house developed software enables high throughput processing of complex multidimensional data. The practicability is demonstrated analyzing [U-13C]-glucose exposed prostate cancer and non-cancer cells. This CE-MS-driven analytical strategy complements polar metabolite profiles through isotopologue labeling patterns, thereby improving not only the metabolomic coverage, but also the understanding of metabolism. 相似文献
10.