全文获取类型
收费全文 | 20894篇 |
免费 | 3645篇 |
国内免费 | 3096篇 |
专业分类
化学 | 15921篇 |
晶体学 | 312篇 |
力学 | 1243篇 |
综合类 | 215篇 |
数学 | 2434篇 |
物理学 | 7510篇 |
出版年
2024年 | 24篇 |
2023年 | 342篇 |
2022年 | 705篇 |
2021年 | 696篇 |
2020年 | 726篇 |
2019年 | 847篇 |
2018年 | 683篇 |
2017年 | 679篇 |
2016年 | 997篇 |
2015年 | 1049篇 |
2014年 | 1249篇 |
2013年 | 1555篇 |
2012年 | 1929篇 |
2011年 | 1908篇 |
2010年 | 1461篇 |
2009年 | 1411篇 |
2008年 | 1495篇 |
2007年 | 1303篇 |
2006年 | 1233篇 |
2005年 | 1151篇 |
2004年 | 884篇 |
2003年 | 692篇 |
2002年 | 742篇 |
2001年 | 588篇 |
2000年 | 479篇 |
1999年 | 389篇 |
1998年 | 325篇 |
1997年 | 321篇 |
1996年 | 277篇 |
1995年 | 235篇 |
1994年 | 219篇 |
1993年 | 152篇 |
1992年 | 138篇 |
1991年 | 125篇 |
1990年 | 126篇 |
1989年 | 97篇 |
1988年 | 86篇 |
1987年 | 44篇 |
1986年 | 61篇 |
1985年 | 46篇 |
1984年 | 24篇 |
1983年 | 21篇 |
1982年 | 19篇 |
1981年 | 10篇 |
1980年 | 11篇 |
1975年 | 8篇 |
1972年 | 7篇 |
1965年 | 6篇 |
1964年 | 5篇 |
1936年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
采用表面光滑玻璃珠作为载体材料,用1:40的腹泻性大肠杆菌诊断血清进行包被。可制成免疫珠。这种免疫珠能与腹泻性大肠杆菌发生特异性结合。经乳糖蛋白胨培养液培养,然后根据其产酸产气进行判断。能在18h内完成腹泻性大肠杆菌的检测。其灵敏度为样液中含有腹泻性大肠杆菌数必须大于10CFu/mL.该法简单、快速、易操作、灵敏度高。 相似文献
72.
In this Note, we consider some classes of nonlinear partial differential equations with regular singularity with respect to t=0 and irregular one with respect to x=0. Our purpose is to establish a result which is similar to the k-summability property, known in the case of singular ordinary differential equations. We can prove that, except at most a countable set, the formal solution is Borel summable or k-summable with respect to x in all other directions. To cite this article: Z. Luo et al., C. R. Acad. Sci. Paris, Ser. I 336 (2003). 相似文献
73.
Through arylsulfonyl activation of thiourea, efficient synthesis of oligomeric guanidines can be achieved in either solution or solid-phase. Incorporation of TFA-sensitive arylsulfonyl groups, such as Pbf, during the synthesis greatly simplifies deprotection procedures for obtaining the final oligomeric guanidine products. 相似文献
74.
KunHuaLIN MaoPingSONG ChenXiaDU QiaoHongZHANG YangJieWU 《中国化学快报》2003,14(7):673-676
The cyclomercurated ferrocenylimines containing heterocyclic ring were prepared by the condensation of cyclomercuration of acylferrocene with the appropriate heterocyclic amine.This procedure provides an efficient method for the synthesis of cyclomerucurated ferrocenylimines containing heterocyclic ring which are difficultly synthesized by the conventional method.The reaction mechanism is proposed. 相似文献
75.
Hua Jin Zhuangqi Hu Qingmin Liu Yunlong Ge Changxu Shi 《Applied Physics A: Materials Science & Processing》1992,54(5):399-403
A crystallization study has been carried out for rapidly solidified Bi2Pb0.5Sr2Ca4Cu5Ox glass. Glass transition temperature T
g, crystallized superconducting phases and microstructural changes were measured and analysed by differential thermal analysis (DTA), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The crystallization mechanism of the three superconducting phases — (2201) 20 K phase, (2212) 80 K phase, and (2223) 110 K phase — has been discussed, and a time-temperature-transformation diagram for the glass has been constructed. 相似文献
76.
BAHADURASYMPTOTICEFFICIENCYINASEMIPARAMETRICREGRESSIONMODEL¥LIANGHUA;CHENGPINGAbstract:TheauthorSgiveMLEθ1MLofθ1inthemodelY=θ... 相似文献
77.
类锂硅离子软X射线激光研究 总被引:1,自引:0,他引:1
在激光等离子体典型参数条件下,利用碰撞-辐模型计算了类锂硅离子5f-3d和4f-3d跃的粒子数反转比率和激光增益系数。讨论了不同热带条件和不同冷却速度下,激光增益系统数的变化。计算结果表明,高功率,短脉冲激光生产的高温等离子体在快速冷却条件下能产生软X射的线激光增益。 相似文献
78.
79.
Cun Feng Fan David A. Waldman Shaw Ling Hsu 《Journal of Polymer Science.Polymer Physics》1991,29(2):235-246
Raman mechanical spectroscopy was used to examine interfacial effects on the stress distribution in model polydiacetylene fiber/epoxy composites. Epoxy release agents were coated on fiber surfaces to modify the interfacial adhesion properties. The modified fiber surfaces were then characterized by scanning electron microscopy and x-ray photoelectron spectroscopy as well as optical microscopy. No difference in the maximum stress value or stress distribution was observed for the two types of fibers, coated or uncoated, used in composites. This suggests that adhesion properties at the composite interface do not affect tensile stress transfer efficiency nor, therefore, the composite tensile modulus along the fiber axis direction in uniaxial composites. Experimental data were also compared with theoretical calculations assuming perfect bonding between fiber and matrix, and idealized frictional force transfer mechanism at the fiber–matrix interface. 相似文献
80.