全文获取类型
收费全文 | 9523篇 |
免费 | 1327篇 |
国内免费 | 1035篇 |
专业分类
化学 | 6977篇 |
晶体学 | 105篇 |
力学 | 487篇 |
综合类 | 110篇 |
数学 | 1191篇 |
物理学 | 3015篇 |
出版年
2024年 | 28篇 |
2023年 | 172篇 |
2022年 | 294篇 |
2021年 | 313篇 |
2020年 | 349篇 |
2019年 | 335篇 |
2018年 | 264篇 |
2017年 | 279篇 |
2016年 | 456篇 |
2015年 | 418篇 |
2014年 | 568篇 |
2013年 | 722篇 |
2012年 | 866篇 |
2011年 | 861篇 |
2010年 | 607篇 |
2009年 | 537篇 |
2008年 | 608篇 |
2007年 | 522篇 |
2006年 | 451篇 |
2005年 | 373篇 |
2004年 | 356篇 |
2003年 | 321篇 |
2002年 | 345篇 |
2001年 | 271篇 |
2000年 | 169篇 |
1999年 | 211篇 |
1998年 | 138篇 |
1997年 | 108篇 |
1996年 | 129篇 |
1995年 | 98篇 |
1994年 | 99篇 |
1993年 | 90篇 |
1992年 | 77篇 |
1991年 | 77篇 |
1990年 | 47篇 |
1989年 | 52篇 |
1988年 | 32篇 |
1987年 | 31篇 |
1986年 | 33篇 |
1985年 | 31篇 |
1984年 | 11篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 8篇 |
1980年 | 7篇 |
1963年 | 7篇 |
1959年 | 12篇 |
1958年 | 11篇 |
1957年 | 15篇 |
1956年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Preparation and mass spectrometric study of egg yolk antibody (IgY) against rabies virus 总被引:6,自引:0,他引:6
Rabies virus was used as the antigen to immunize laying chickens. Anti-rabies virus immunoglobulin Y(IgY) was isolated from yolks of the eggs laid by these chickens using a two-step salt precipitation and one-step gel filtration protocol. The purified IgY was reduced with dithiothreitol, and heavy chains (HC) and light chains (LC) were obtained. In addition, the purified IgY was digested with pepsin and the fragment with specific antigen binding properties (Fab) was produced. Using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOFMS), the average molecular weights of IgY, HC, LC, and Fab were determined as 167 250, 65 105, 18 660, and 45,359 Da, respectively. IgY has two structural differences compared with mammalian IgGs. First, the molecular weight of the heavy chain of IgY is larger than that of its mammalian counterpart, while the molecular weight of the light chain of IgY is smaller. Second, upon pepsin digestion, anti-rabies virus IgY is degraded into Fab, in contrast to mammalian IgG, which has been reported to be degraded into F(ab')(2) under the same conditions. 相似文献
992.
We demonstrate the self-assembly of three types of parallel gold nanorod clusters using a rod-like DNA origami as the template. 相似文献
993.
研究了一类双参数高阶非线性奇摄动方程边值问题,利用合成展开法构造出形式渐近解,再利用微分不等式理论证明了解的存在一致有效性. 相似文献
994.
Dr. Misook Oh Dr. Ji Hoon Lee Heejo Moon Yu‐Jung Hyun Prof. Dr. Hyun‐Suk Lim 《Angewandte Chemie (International ed. in English)》2016,55(2):602-606
Skp2 is thought to have two critical roles in tumorigenesis. As part of the SCFSkp2 ubiquitin ligase, Skp2 drives the cell cycle by mediating the degradation of cell cycle proteins. Besides the proteolytic activity, Skp2 also blocks p53‐mediated apoptosis by outcompeting p53 for binding p300. Herein, we exploit the Skp2/p300 interaction as a new target for Skp2 inhibition. An affinity‐based high‐throughput screen of a combinatorial cyclic peptoid library identified an inhibitor that binds to Skp2 and interferes with the Skp2/p300 interaction. We show that antagonism of the Skp2/p300 interaction by the inhibitor leads to p300‐mediated p53 acetylation, resulting in p53‐mediated apoptosis in cancer cells, without affecting Skp2 proteolytic activity. Our results suggest that inhibition of the Skp2/p300 interaction has a great potential as a new anticancer strategy, and our Skp2 inhibitor can be developed as a chemical probe to delineate Skp2 non‐proteolytic function in tumorigenesis. 相似文献
995.
996.
In this paper, a new type of organophilic montmorillonites, co-treated by octadecylammonium and aminoundecanoic acid, were synthesized and applied to prepare nylon 66/montmorillonite nanocomposites via melt compounding in a twin extruder. WAXD and TEM characterization indicate that a disordered structure was derived and the montmorillonite platelets dispersed in nanoscale in the nylon 66 matrix. The nanocomposites with co-treated montmorillonite display comparatively higher strength and modulus compared to nylon 66 matrix. 相似文献
997.
Singular value decomposition with normalized period for magnetocaridiography signal processing 下载免费PDF全文
In this paper, we have developed an algorithm based on singular value
decomposition (SVD) for matrix. And the novel SVD algorithm with normalized
period of cardiac cycles is presented. The results from real
magnetocardiography (MCG) data processing show that the new algorithm is
better than the standard one not only in suppressing noises, but also in
providing high-fidelity MCG signals. 相似文献
998.
The hydrophilic monomer acrylamide (AM) and hydrophobic monomer styrene (St) have been directly copolymerized in a surfactant‐free aqueous emulsion with the assistance of powerful ultrasound. Fourier Transform Infrared spectrocopy (FT‐IR), nuclear magnetic resonance (NMR), and differential scanning calorimetry (DSC) measurements revealed that copolymers of AM and St were obtained. Elemental analysis was used to calculate the composition of the copolymer. Size exclusion chromatography (SEC) measurement showed that the molecular weight (Mw) of the copolymer is 1.86 × 105 g/mol and the polydispersity index (PDI( = 2.31. The self‐assembly behavior in different solvents was investigated utilizing laser light scattering (LLS), atomic force microscopy (AFM), and transmission electron microscopy (TEM); the copolymer film showed amphiphilicity, as measured by contact angle goniometry. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
999.
Xinfeng Chen Kui Zhang Huan Yu Long Yu Hongwei Ge Ji Yue Tianxin Hou Abdullah M. Asiri Hadi M. Marwani Suhua Wang 《Journal of Radioanalytical and Nuclear Chemistry》2018,316(3):1011-1019
Herein we report a fluorescent method for sensitive and selective detection of uranyl ions using CdTe quantum dots functionalized with mercaptopropionic acid, which the fluorescence of the quantum dots could be quantitatively quenched through electron transfer mechanism. The detection limit of the method was estimated to be 4 nM, less than the maximum allowed content of 130 nM for uranyl in drinking water defined by the U.S. Environmental Protection Agency. Furthermore, the probe was successfully applied in detection of uranyl ions in real samples, demonstrating its potential practical applications for monitoring of uranyl ions in environment. 相似文献
1000.
Combination of affinity extraction procedures with mass spectrometric analyses is termed affinity-directed mass spectrometry, a technique that has gained broad interest in immunology and is extended here with several improvements from methods used in previous studies. A monoclonal antibody was immobilized on a nitrocellulose (NC) membrane, allowing the corresponding antigen to be selectively captured from a complex solution for analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). This method was also used to rapidly determine the approximate binding region responsible for the antibody/antigen interaction. The tryptic fragments of antigen protein in buffer were applied to the antibody immobilized on NC film and allowed to interact. The NC film was then washed to remove salts and other unbound components, and subjected to analysis by MALDI-TOFMS. Using interferon-alpha(2a) and anti-interferon-alpha(2a) monoclonal antibody IgG as a model system, we successfully extracted the antigen protein and determined the approximate binding region for the antigen/antibody interaction (i.e., the tryptic fragment responsible). 相似文献