全文获取类型
收费全文 | 76440篇 |
免费 | 4149篇 |
国内免费 | 2566篇 |
专业分类
化学 | 40051篇 |
晶体学 | 1076篇 |
力学 | 4228篇 |
综合类 | 126篇 |
数学 | 7293篇 |
物理学 | 30381篇 |
出版年
2023年 | 528篇 |
2022年 | 801篇 |
2021年 | 1059篇 |
2020年 | 1280篇 |
2019年 | 1174篇 |
2018年 | 1231篇 |
2017年 | 1114篇 |
2016年 | 1833篇 |
2015年 | 1525篇 |
2014年 | 2016篇 |
2013年 | 3886篇 |
2012年 | 3933篇 |
2011年 | 4700篇 |
2010年 | 3292篇 |
2009年 | 3222篇 |
2008年 | 3965篇 |
2007年 | 3643篇 |
2006年 | 3380篇 |
2005年 | 3025篇 |
2004年 | 2659篇 |
2003年 | 2340篇 |
2002年 | 2292篇 |
2001年 | 3512篇 |
2000年 | 2565篇 |
1999年 | 1957篇 |
1998年 | 1335篇 |
1997年 | 1277篇 |
1996年 | 1114篇 |
1995年 | 1045篇 |
1994年 | 925篇 |
1993年 | 762篇 |
1992年 | 1094篇 |
1991年 | 1079篇 |
1990年 | 950篇 |
1989年 | 824篇 |
1988年 | 776篇 |
1987年 | 842篇 |
1986年 | 715篇 |
1985年 | 918篇 |
1984年 | 848篇 |
1983年 | 586篇 |
1982年 | 573篇 |
1981年 | 542篇 |
1980年 | 497篇 |
1979年 | 618篇 |
1978年 | 644篇 |
1977年 | 658篇 |
1976年 | 573篇 |
1975年 | 483篇 |
1974年 | 522篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
A graphic sequence π =(d1, d2,..., dn) is said to be forcibly k-edge-connected if every realization of π is k-edge-connected. In this paper, we obtain a new sufficient degree condition for π to be forcibly k-edgeconnected. We also show that this new sufficient degree condition implies a strongest monotone degree condition for π to be forcibly 2-edge-connected and a conjecture about a strongest monotone degree condition for π to be forcibly 3-edge-connected due to... 相似文献
12.
Physics of Atomic Nuclei - We have investigated the robustness of the spin-navigator based method for manipulating the beam polarization to bend magnet installation errors. Toward that end,... 相似文献
13.
Science China Mathematics - Linear factor models are familiar tools used in many fields. Several pioneering literatures established foundational theoretical results of the quasi-maximum likelihood... 相似文献
14.
Dr. Yulia Y. Enakieva Dr. Anna A. Sinelshchikova Prof. Mikhail S. Grigoriev Prof. Vladimir V. Chernyshev Dr. Konstantin A. Kovalenko Prof. Irina A. Stenina Prof. Andrey B. Yaroslavtsev Prof. Yulia G. Gorbunova Prof. Aslan Y. Tsivadze 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(45):10552-10556
The design of new solid-state proton-conducting materials is a great challenge for chemistry and materials science. Herein, a new anionic porphyrinylphosphonate-based MOF ( IPCE-1Ni ), which involves dimethylammonium (DMA) cations for charge compensation, is reported. As a result of its unique structure, IPCE-1Ni exhibits one of the highest value of the proton conductivity among reported proton-conducting MOF materials based on porphyrins (1.55×10−3 S cm−1 at 75 °C and 80 % relative humidity). 相似文献
15.
Complex Study of the Spearhead Superficial Crust from Burial Mound no. 1 near Novosvobodnaya Village
Loboda A. Yu. Kolobylina N. N. Veligzhanin A. A. Zubavitchus Y. V. Tereshchenko E. Yu. Shishlina N. I. Yatsishina E. B. Kashkarov P. K. 《Crystallography Reports》2018,63(2):295-301
A complex study of a spearhead dated back to IV mill. BC from burial mound no. 1 near Novosvobodnaya village (collection of the State Historical Museum) and, in particular, the material of spearhead superficial crust has been performed. The elemental and phase composition of the metal of spearhead and the superficial crust on its surface have been determined by scanning electron microscopy, jointly with energydispersive X-ray microanalysis and X-ray phase analysis. A comparative analysis of the results of studying the spearhead superficial crust and similar crusts on other artifacts from the mounds near Novosvobodnaya village suggest natural origin of the crust on copper?arsenic artifacts.
相似文献16.
In the paper, the authors establish several integral representations for the generating functions of the large and little Schröder numbers and for the large and little Schröder numbers. 相似文献
17.
18.
19.
Su X. F. Zhang Y. L. Maximov A. L. Zhang K. Xin Q. Feng C. Q. Bai X. F. Wu W. 《Russian Journal of Applied Chemistry》2020,93(1):127-136
Russian Journal of Applied Chemistry - Nanoscale ZSM-5 (AlZ5-D) and Ga-substituted ZSM-5 zeolites ((Al,Ga)Z5-D and GaZ5-D) were synthesized by a green dry-gel conversion strategy. For comparison,... 相似文献
20.
Synthesis of Small‐Sized,Porous, and Low‐Toxic Magnetite Nanoparticles by Thin POSS Silica Coating 下载免费PDF全文
Dr. Swee Kuan Yen D. Prathyusha Varma Wei Mei Guo Dr. Vincent H. B. Ho Dr. Vimalan Vijayaragavan Dr. Parasuraman Padmanabhan Prof. Kishore Bhakoo Prof. Subramanian Tamil Selvan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(10):3914-3918
In this communication, we report the synthesis of small‐sized (<10 nm), water‐soluble, magnetic nanoparticles (MNPs) coated with polyhedral oligomeric silsesquioxanes (POSS), which contain either polyethylene glycol (PEG) or octa(tetramethylammonium) (OctaTMA) as functional groups. The POSS‐coated MNPs exhibit superparamagnetic behavior with saturation magnetic moments (51–53 emu g?1) comparable to silica‐coated MNPs. They also provide good colloidal stability at different pH and salt concentrations, and low cytotoxicity to MCF‐7 human breast epithelial cells. The relaxivity data and magnetic resonance (MR) phantom images demonstrate the potential application of these MNPs in bioimaging. 相似文献