全文获取类型
收费全文 | 13712篇 |
免费 | 1526篇 |
国内免费 | 920篇 |
专业分类
化学 | 8943篇 |
晶体学 | 148篇 |
力学 | 685篇 |
综合类 | 63篇 |
数学 | 1827篇 |
物理学 | 4492篇 |
出版年
2023年 | 201篇 |
2022年 | 418篇 |
2021年 | 404篇 |
2020年 | 430篇 |
2019年 | 459篇 |
2018年 | 384篇 |
2017年 | 356篇 |
2016年 | 524篇 |
2015年 | 556篇 |
2014年 | 609篇 |
2013年 | 922篇 |
2012年 | 1027篇 |
2011年 | 1116篇 |
2010年 | 697篇 |
2009年 | 615篇 |
2008年 | 755篇 |
2007年 | 671篇 |
2006年 | 677篇 |
2005年 | 552篇 |
2004年 | 424篇 |
2003年 | 414篇 |
2002年 | 330篇 |
2001年 | 312篇 |
2000年 | 295篇 |
1999年 | 283篇 |
1998年 | 211篇 |
1997年 | 192篇 |
1996年 | 194篇 |
1995年 | 168篇 |
1994年 | 201篇 |
1993年 | 138篇 |
1992年 | 152篇 |
1991年 | 147篇 |
1990年 | 110篇 |
1989年 | 79篇 |
1988年 | 79篇 |
1987年 | 71篇 |
1986年 | 62篇 |
1985年 | 82篇 |
1984年 | 72篇 |
1983年 | 57篇 |
1982年 | 67篇 |
1981年 | 55篇 |
1980年 | 59篇 |
1979年 | 51篇 |
1978年 | 58篇 |
1977年 | 52篇 |
1976年 | 46篇 |
1975年 | 37篇 |
1973年 | 39篇 |
排序方式: 共有10000条查询结果,搜索用时 483 毫秒
1.
Zeng Qing-Wei Wen Zhuo-Yu Fu Jun-Feng Zhou Nan-Run 《International Journal of Theoretical Physics》2021,60(9):3306-3333
International Journal of Theoretical Physics - A new quantum watermark algorithm is presented by combining maximum pixel difference partitioning with the least significant bit substitution... 相似文献
2.
We consider concentrated vorticities for the Euler equation on a smooth domain in the form of supported on well-separated vortical domains , , of small diameters . A conformal mapping framework is set up to study this free boundary problem with being part of unknowns. For any given vorticities and small , through a perturbation approach, we obtain such piecewise constant steady vortex patches as well as piecewise smooth Lipschitz steady vorticities, both concentrated near non-degenerate critical configurations of the Kirchhoff–Routh Hamiltonian function. When vortex patch evolution is considered as the boundary dynamics of , through an invariant subspace decomposition, it is also proved that the spectral/linear stability of such steady vortex patches is largely determined by that of the 2N-dimensional linearized point vortex dynamics, while the motion is highly oscillatory in the 2N-codim directions corresponding to the vortical domain shapes. 相似文献
3.
4.
5.
6.
Acta Mathematica Sinica, English Series - We are interested in the existence and asymptotic behavior for the least energy solutions of the following fractional eigenvalue problem $$\left({\rm{P}}... 相似文献
7.
以1,4-二溴-2,5-二甲基苯和4-吡啶硼酸为原料,经两步合成了一种新颖的含吡啶基团的二羧酸配体。通过核磁共振氢谱及傅里叶变换红外光谱对配体结构进行表征,通过热重分析对配体的热稳定性进行了测试;通过溶剂热法对配体的单晶进行培养,并考察反应温度、时间、pH和溶剂等条件对单晶培养的影响。结果表明:在反应温度为80 ℃,反应时间为12 h、溶剂为蒸馏水、溶液pH=5的条件下可获得高质量单晶。该配体为单斜晶系,属于C2/c空间群,结构中含有4个氧原子和2个氮原子,可为金属离子的配位提供足够的位点,有望应用于配合物的设计或催化、吸附和医药载体等行业。 相似文献
8.
Ding Q. Yao M. Wu Sh. Zeng M. Xue N. Wu D. Xu J. 《Journal of Applied Spectroscopy》2022,89(4):712-718
Journal of Applied Spectroscopy - Based on partial least squares (PLS) analysis, the effects of different smoothing points and different preprocessing methods on the accuracy and precision of the... 相似文献
9.
Over the past two decades, advanced materials with hollow interiors have received significant attention in materials research owing to their great application potential across a vast number of technological fields. Though with great difficulty, multi-shelled hollow metal–organic frameworks (MSHMs) have also been successfully synthesized in recent years. Herein, a rational shell-by-shell soft-templating protocol has been devised to fabricate highly uniform multi-shelled hollow cobalt-imidazole-based MOF (ZIF-67). For the first time, it has become possible to endow mesoporosity to this new type of functional material (i.e., mesoporous MOFs). When used as carrier materials in catalytic reactions, in principle, these mesoporous MSHMs with high surface area not only improve the dispersity of metal nanoparticles (NPs), but also efficiently facilitate the mass diffusion of the reactions, resulting in enhanced catalyst activity. Moreover, the obtained MSHMs/M nanocomposites serve as base-metal bifunctional catalysts for one-pot oxidation-Knoevenagel condensation cascade reaction, in which the MSHMs itself serves as a pristine active catalyst in addition to its role of catalyst support. The results demonstrate that excellent multifunctional catalysts can be achieved via preparing intrinsically microporous bulk MOFs into extrinsically mesoporous MSHMs which possess many structural merits that conventional bulk MOFs do not have. 相似文献
10.
An N. Le Ruiqi Liang Xiaoyu Ji Xiaowei Fu Mingjiang Zhong 《Journal of polymer science. Part A, Polymer chemistry》2021,59(21):2571-2580
The random copolymerization of norbornene-functionalized macromonomers was explored as a method of synthesizing mixed-graft block copolymers (mGBCPs). The copolymerization kinetics of a model system of polystyrene (PS) and poly(lactic acid) (PLA) macromonomers was first analyzed, revealing a gradient composition of side chains along the mGBCP backbone. The phase separation behavior of mGBCPs with PS and PLA side chains of various backbone lengths and side chain molar ratios was investigated, and increasing the backbone length was found to stabilize the phase-separated nanostructures. The graft architecture was also demonstrated to improve the processability of the mGBCP, compared to a linear counterpart. Investigations of mGBCPs comprised of polydimethylsiloxane and poly(ethylene oxide) side chains exemplified the diverse self-assembled morphologies, including a Frank-Kasper A15 phase, that can be obtained with mGBCPs synthesized by random copolymerization of macromonomers. Lastly, a ternary mGBCP was synthesized by the copolymerization of three macromonomers. 相似文献