全文获取类型
收费全文 | 176030篇 |
免费 | 29209篇 |
国内免费 | 7803篇 |
专业分类
化学 | 142573篇 |
晶体学 | 1770篇 |
力学 | 8121篇 |
综合类 | 435篇 |
数学 | 17240篇 |
物理学 | 42903篇 |
出版年
2023年 | 4832篇 |
2022年 | 3602篇 |
2021年 | 5059篇 |
2020年 | 8309篇 |
2019年 | 7432篇 |
2018年 | 5869篇 |
2017年 | 4516篇 |
2016年 | 10999篇 |
2015年 | 10028篇 |
2014年 | 10724篇 |
2013年 | 13077篇 |
2012年 | 11098篇 |
2011年 | 9352篇 |
2010年 | 10034篇 |
2009年 | 9899篇 |
2008年 | 8242篇 |
2007年 | 7114篇 |
2006年 | 5952篇 |
2005年 | 5554篇 |
2004年 | 4883篇 |
2003年 | 4404篇 |
2002年 | 5247篇 |
2001年 | 4264篇 |
2000年 | 3584篇 |
1999年 | 2347篇 |
1998年 | 1890篇 |
1997年 | 1689篇 |
1996年 | 1652篇 |
1995年 | 1466篇 |
1994年 | 1447篇 |
1993年 | 1438篇 |
1992年 | 1282篇 |
1991年 | 1332篇 |
1990年 | 1270篇 |
1989年 | 1174篇 |
1988年 | 1044篇 |
1987年 | 1023篇 |
1986年 | 989篇 |
1985年 | 1012篇 |
1984年 | 1003篇 |
1983年 | 911篇 |
1982年 | 884篇 |
1979年 | 896篇 |
1978年 | 907篇 |
1977年 | 968篇 |
1976年 | 1101篇 |
1975年 | 999篇 |
1974年 | 1039篇 |
1973年 | 957篇 |
1972年 | 903篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
993.
994.
Alexei A. Belik Andrei V. Mironov Roman V. Shpanchenko Eiji Takayama‐Muromachi 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(7):i37-i39
The crystal structure of a new high‐pressure modification of cadmium divanadium hexaoxide, CdV2O6, was refined from X‐ray single‐crystal data. It contains zigzag chains of edge‐sharing VO6 octahedra. Octahedra in adjacent chains share corners and form corrugated layers. Octahedrally coordinated Cd atoms, which lie on twofold axes, are situated between the layers. The columbite‐like structure results in a strong distortion of the CdO6 octahedra which may be stabilized only at high pressure. 相似文献
995.
We reported controllable synthesis of ZnS nanocrystal-polymer transparent hybrids by using polymethylmethacrylate (PMMA) as
a polymer matrix. In a typical run, the appropriate amounts of zinc chloride (ZnCl2) and sodium sulfide (Na2S) in the presence of 2-mercaptoethanol (ME) as the organic ligand were well dispersed in H2O/dimethylformamide solution without any aggregation. In addition, the Mn-doped ZnS nanocrystals (NCs) were synthesized with
similar method. Then, ZnS-PMMA hybrids were obtained via free radical polymerization in situ by using ZnS NCs functionalized
with methacryloxypropyltrimethoxysilane (MPS). FT-IR characterization indicates the formation of robust bonding between ZnS
NCs and the organic ligand. The TEM images show that ZnS NCs are well dispersed in PMMA matrix, and particle size of as-prepared
ZnS NCs is about 2.6 nm, in agreement with the computing results of Brus’s model and Debye–Scherrer formula. The photoluminescence
measurements present that ZnS NCs, Mn-doped ZnS NCs, and ZnS/PMMA hybrid show good optical properties. 相似文献
996.
R. I. Jalmakhanbetova V. A. Raldugin I. Yu. Bagryanskaya Yu. V. Gatilov M. M. Shakirov G. A. Atazhanova S. M. Adekenov 《Chemistry of Natural Compounds》2007,43(5):552-554
Adducts of dihalocarbenes generated from chloroform and bromoform were prepared by reaction with estafiatin guaianolide. Their
structures were established by XSA.
__________
Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 453–455, September–October, 2007. 相似文献
997.
Tumor cells transduced with herpes simplex virus thymidine kinase gene have been intensively applied to the field of positron emission tomography via imaging of its substrate. As a pilot synthesis approach, a facile preparation of 5‐[125I] iodoarabinosyl uridine starting from commercially available uridine is reported herein. 相似文献
998.
Ivica ?ilovi Dubravka Matkovi‐alogovi Ivan Kos Mladen Biru Milena Jadrijevi‐Mladar Taka
《Acta Crystallographica. Section C, Structural Chemistry》2007,63(1):o45-o47
In the crystal structures of two cyclic trihydroxamic acid derivatives containing the same substructure unit, viz. 1,3,5‐trihydroxy‐1,3,5‐triazinane‐2,4,6‐trione dihydrate, C3H3N3O6·2H2O, (I), and 1,3,5‐benzyloxy‐1,3,5‐triazinane‐2,4,6‐trione, C24H21N3O6, (II), there is no significant difference in the geometric parameters. In (I), there are 11 hydrogen bonds of the O—H⋯O type interconnecting the molecules in a three‐dimensional network, while in (II) there are only two weak C—H⋯O hydrogen bonds. The results of IR spectroscopic analysis are in good agreement with the crystallographic study. 相似文献
999.
I. L. Valuev Yu. A. Talyzenkov I. V. Obydennova L. I. Valuev N. A. Platé 《Polymer Science Series B》2007,49(5-6):148-151
N,N-Diethylacrylamide-N-acryloylphthalimide copolymers have been synthesized. The LCST of the synthesized copolymers decreases with increase in both the molecular mass of the copolymers and the content of more hydrophobic N-acryloylphthalimide units. Through the reaction of the copolymers with the proteinase enzyme inhibitor, ovomucoid, the polymer derivatives of protein have been prepared. It has been shown that the biological activity of ovomucoid and the LCST of polymer derivatives increase with the amount of the immobilized ovomucoid. The effect of biologically active media on the LCST values of polymer derivatives has been studied. 相似文献
1000.