全文获取类型
收费全文 | 9145篇 |
免费 | 261篇 |
国内免费 | 63篇 |
专业分类
化学 | 6104篇 |
晶体学 | 88篇 |
力学 | 286篇 |
综合类 | 1篇 |
数学 | 1432篇 |
物理学 | 1558篇 |
出版年
2022年 | 84篇 |
2021年 | 87篇 |
2020年 | 157篇 |
2019年 | 118篇 |
2018年 | 89篇 |
2017年 | 108篇 |
2016年 | 200篇 |
2015年 | 156篇 |
2014年 | 204篇 |
2013年 | 417篇 |
2012年 | 479篇 |
2011年 | 579篇 |
2010年 | 294篇 |
2009年 | 235篇 |
2008年 | 518篇 |
2007年 | 482篇 |
2006年 | 470篇 |
2005年 | 471篇 |
2004年 | 440篇 |
2003年 | 303篇 |
2002年 | 321篇 |
2001年 | 109篇 |
2000年 | 95篇 |
1999年 | 73篇 |
1998年 | 85篇 |
1997年 | 106篇 |
1996年 | 150篇 |
1995年 | 91篇 |
1994年 | 82篇 |
1993年 | 107篇 |
1992年 | 79篇 |
1991年 | 90篇 |
1990年 | 85篇 |
1989年 | 70篇 |
1988年 | 83篇 |
1987年 | 72篇 |
1986年 | 64篇 |
1985年 | 126篇 |
1984年 | 141篇 |
1983年 | 105篇 |
1982年 | 120篇 |
1981年 | 120篇 |
1980年 | 99篇 |
1979年 | 88篇 |
1978年 | 118篇 |
1977年 | 101篇 |
1976年 | 94篇 |
1975年 | 80篇 |
1974年 | 74篇 |
1973年 | 69篇 |
排序方式: 共有9469条查询结果,搜索用时 15 毫秒
31.
32.
33.
The synthesis of indole ring-fused benzazepinone series as latonduine derivatives has been developed via an intramolecular Heck reaction. The scope has been enlarged not only to indole moiety but also to pyrrolo and benzo[b]thiophene nuclei. Several derivatives prepared have been evaluated in vitro for their antiproliferative activities on breast cancer cell lines. Some of them showed promising cytotoxic activities. 相似文献
34.
35.
Hua Zhang Nabil A. Amro Robert Elghanian Joseph Fragala 《Applied Surface Science》2006,253(4):1960-1963
A method, combining micro-contact printing (μCP), wet chemical etching and reactive ion etching (RIE), is reported to fabricate microstructures on Si and SiOx. Positive and negative structures were generated based on different stamps used for μCP. The reproducibility of the obtained microstructures shows the methodology reported herein could be useful in Micro-Electro-Mechanical Systems (MEMS), optical and biological sensing applications. 相似文献
36.
The synthesis and characterization of a collagen mimetic dendrimer composed of the Gly-Pro-Nleu sequence is described. The dendrimer is built on a ‘first generation’ poly(amidoamine) core and is synthesized in 38% yield. This dendrimer exhibits a melting temperature of 25 °C, which is in between previously studied analogous molecules of identical sequence and length. 相似文献
37.
The incidence of the cutaneous malignant melanoma is increasing rapidly in the world [Ferlay J, Bray F, Pisani P, et al. GLOBOCAN 2000: Cancer incidence, mortality and prevalence worldwide, Version 1.0 IARC Cancer Base no. 5. Lyon: IARC Press, 2001]. The therapeutic address requires a method having high sensitivity and capability to diagnose such disease at an early stage. We introduce a new diagnostic method based on non-linear methodologies. In detail we suggest that fractal as well as noise and chaos dynamics are the most important components responsible for genetic instability of melanocytes. As consequence we introduce the new technique of the variogram and of fractal analysis extended to the whole regions of interest of skin in order to obtain parameters able to identify the malignant lesion. In a preliminary analysis, satisfactory results are reached. 相似文献
38.
39.
40.
This paper reports a direct jet-based polymerisation by polycondensation approach to forming a self-supporting scaffold structure.
The processing technique is electrospraying, which is also known as electrohydrodynamic atomization. A specially formulated
ethanolic siloxane sol derived from alkoxysilanes was synthesised and electrosprayed using a ring-shaped ground electrode
configuration. The medium was seen to electrospray in the stable cone-jet mode, which later gave rise to the growing or forming
of “fir-tree” like structures. The materials were characterised using microscopy, solid state NMR, FTIR, XRD and DSC. Hence
this paper explains the direct controlled polycondensation from the siloxane sol and further presents the basis by which these
scaffolds take shape. 相似文献