全文获取类型
收费全文 | 37555篇 |
免费 | 6741篇 |
国内免费 | 5074篇 |
专业分类
化学 | 26473篇 |
晶体学 | 488篇 |
力学 | 2467篇 |
综合类 | 420篇 |
数学 | 4674篇 |
物理学 | 14848篇 |
出版年
2024年 | 47篇 |
2023年 | 777篇 |
2022年 | 979篇 |
2021年 | 1301篇 |
2020年 | 1598篇 |
2019年 | 1524篇 |
2018年 | 1350篇 |
2017年 | 1363篇 |
2016年 | 1883篇 |
2015年 | 1828篇 |
2014年 | 2252篇 |
2013年 | 2957篇 |
2012年 | 3470篇 |
2011年 | 3536篇 |
2010年 | 2538篇 |
2009年 | 2451篇 |
2008年 | 2674篇 |
2007年 | 2308篇 |
2006年 | 2132篇 |
2005年 | 1774篇 |
2004年 | 1324篇 |
2003年 | 1043篇 |
2002年 | 904篇 |
2001年 | 787篇 |
2000年 | 704篇 |
1999年 | 785篇 |
1998年 | 660篇 |
1997年 | 614篇 |
1996年 | 558篇 |
1995年 | 540篇 |
1994年 | 454篇 |
1993年 | 397篇 |
1992年 | 329篇 |
1991年 | 295篇 |
1990年 | 272篇 |
1989年 | 217篇 |
1988年 | 163篇 |
1987年 | 133篇 |
1986年 | 108篇 |
1985年 | 106篇 |
1984年 | 65篇 |
1983年 | 54篇 |
1982年 | 55篇 |
1981年 | 24篇 |
1980年 | 13篇 |
1979年 | 5篇 |
1975年 | 2篇 |
1959年 | 3篇 |
1957年 | 8篇 |
1936年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
1.
Numerical Algorithms - In this paper, we combine the ideas of multilevel augmentation methods for solving integral equations and the shifted-inverse power method to develop a new multilevel... 相似文献
2.
本文演示了紧凑的绿色和近红外双色连续波激光光源,其发射波长分别为516 nm和775 nm。设计并制造了级联的周期性极化掺镁铌酸锂晶体,用于同时转换通信波长的二次谐波(SHG)和三次谐波(THG),可以在相同温度下获得绿色和近红外激光的输出。通过建立一个单程激光测量系统,在2 W泵浦功率下获得516 nm的0.15 mW绿光和775 nm的1.19 mW的光,晶体温度控制在30.8 ℃。实验结果将为单激光器泵浦的紧凑型双波长共线激光器提供重要的案例。 相似文献
3.
Nonlinear Dynamics - The nonlinear modes of a non-conservative nonlinear system are sometimes referred to as damped nonlinear normal modes (dNNMs). Because of the non-conservative... 相似文献
4.
In this paper, we study vanishing and splitting results on a complete smooth metric measure space \((M^n,g,\mathrm {e}^{-f}\mathrm {d}v)\) with various negative m-Bakry-Émery Ricci curvature lower bounds in terms of the first eigenvalue \(\lambda _1(\Delta _f)\) of the weighted Laplacian \(\Delta _f\), i.e., \(\mathrm {Ric}_{m,n}\ge -a\lambda _1(\Delta _f)-b\) for \(0<a\le \dfrac{m}{m-1}, b\ge 0\). In particular, we consider three main cases for different a and b with or without conditions on \(\lambda _1(\Delta _f)\). These results are extensions of Dung and Vieira, and weighted generalizations of Li-Wang, Dung-Sung, and Vieira.
相似文献5.
Designs, Codes and Cryptography - Large sets of combinatorial designs has always been a fascinating topic in design theory. These designs form a partition of the whole space into combinatorial... 相似文献
6.
Nonlinear Dynamics - This article considers a reaction–diffusion predator–prey model with schooling behavior both in predator and prey species and subject to the homogeneous Neumann... 相似文献
7.
Hu Duo-Duo Gao Qian Dai Jing-Cheng Cui Ru Li Yuan-Bo Li Yuan-Ming Zhou Xiao-Guo Bian Kang-Jie Wu Bing-Bing Zhang Kai-Fan Wang Xi-Sheng Li Yan 《中国科学:化学(英文版)》2022,65(4):753-761
Science China Chemistry - A light-induced, nickel-catalyzed three-component arylsulfonation of 1,3-enynes in the absence of photocatalyst is reported. This methodology exhibited mild conditions,... 相似文献
8.
Qi-Feng Zhou 《高分子科学》2022,40(1):1-1
The year 2022 marks the 40th anniversary of the Chinese Journal of Polymer Science(CJPS)—a true milestone to be celebrated!In the early stage of the reform and opening,there was an increasing demand for international academic communications.To facilitate these communications. 相似文献
9.
Hanghang Zhou Dr. Ying Luo Dr. Jun Xu Dr. Lidan Deng Prof. Dr. Zheng Wang Prof. Dr. Hong He 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(68):e202202044
Cubic-like CaTaO2N photocatalysts with high crystallinity and uniform particle size were successfully prepared by the flux-assisted nitridation method. The growth of CaTaO2N single crystals under different synthesis conditions was systematically investigated to understand the effects of the crystallinity and optical property on photocatalytic performance of CO2 reduction. Moreover, the modification of CaTaO2N single crystals with core-shell Ni−Ag bicomponent cocatalyst by two-step decoration process gave a 2.4 times higher amount of CO evolution than the deposition of sole Ag cocatalyst, because of the synergistic effects of bicomponent cocatalyst on the interfacial electron transfer and surface catalytic process. This study provides a valuable way to construct high-crystalline photocatalysts with effective bicomponent cocatalyst for visible-light-driven CO2 reduction with H2O. 相似文献
10.
Nonlinear Dynamics - In this paper, the high-order coupled variable coefficient nonlinear Schrödinger equations is studied. The double-hump soliton solutions for the equations are obtained... 相似文献