全文获取类型
收费全文 | 11351篇 |
免费 | 620篇 |
国内免费 | 36篇 |
专业分类
12007篇 |
出版年
2024年 | 29篇 |
2023年 | 125篇 |
2022年 | 376篇 |
2021年 | 564篇 |
2020年 | 353篇 |
2019年 | 438篇 |
2018年 | 474篇 |
2017年 | 351篇 |
2016年 | 498篇 |
2015年 | 582篇 |
2014年 | 682篇 |
2013年 | 854篇 |
2012年 | 914篇 |
2011年 | 799篇 |
2010年 | 483篇 |
2009年 | 395篇 |
2008年 | 492篇 |
2007年 | 491篇 |
2006年 | 430篇 |
2005年 | 422篇 |
2004年 | 361篇 |
2003年 | 299篇 |
2002年 | 268篇 |
2001年 | 124篇 |
2000年 | 116篇 |
1999年 | 95篇 |
1998年 | 69篇 |
1997年 | 35篇 |
1996年 | 41篇 |
1995年 | 45篇 |
1994年 | 31篇 |
1993年 | 31篇 |
1992年 | 54篇 |
1991年 | 52篇 |
1990年 | 57篇 |
1989年 | 47篇 |
1988年 | 53篇 |
1987年 | 38篇 |
1986年 | 35篇 |
1985年 | 44篇 |
1984年 | 43篇 |
1983年 | 34篇 |
1982年 | 24篇 |
1981年 | 30篇 |
1980年 | 18篇 |
1979年 | 22篇 |
1978年 | 22篇 |
1977年 | 18篇 |
1976年 | 24篇 |
1975年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
3.
4.
S Paul P Heinz-Erian S I Said 《Biochemical and biophysical research communications》1985,130(1):479-485
In a radioassay for Vasoactive Intestinal Peptide (VIP)-binding, eight out of 33 plasma samples from healthy human subjects exhibited specific binding ranging from 2.6% to 46.7% of total [125 I]VIP. This binding was competitively displaced by unlabeled VIP. The structurally homologous peptides, Peptide Histidine Isoleucine (PHI) and secretin, were, respectively, 72-fold and 413-fold less potent than VIP in displacing bound [125 I]VIP, whereas the unrelated peptides, neurotensin, eledoisin, bombesin and metenkephalin, were without effect on the binding. The antibody nature of the VIP-binding factor was suggested by its precipitation with ammonium sulfate, attenuation after absorption with Staphylococcus aureus preparations, precipitation with antisera against human IgG and IgM, and coelution with standard IgG and IgM on anion-exchange and high-performance gel-filtration columns. Pepsin treatment of purified IgG fraction yielded a VIP-binding species with apparent molecular weight of 108 +/- 13 kDa that was precipitated by antiserum against the F(ab)2 fragment of the IgG molecule. These results demonstrate the existence in some human plasmas of an autoantibody that binds VIP. 相似文献
5.
6.
Perspective texture synthesis has great significance in many fields like video editing, scene capturing etc., due to its ability to read and control global feature information. In this paper, we present a novel example-based, specifically energy optimization-based algorithm, to synthesize perspective textures. Energy optimization technique is a pixel-based approach, so it’s time-consuming. We improve it from two aspects with the purpose of achieving faster synthesis and high quality. Firstly, we change this pixel-based technique by replacing the pixel computation with a little patch. Secondly, we present a novel technique to accelerate searching nearest neighborhoods in energy optimization. Using k- means clustering technique to build a search tree to accelerate the search. Hence, we make use of principal component analysis (PCA) technique to reduce dimensions of input vectors. The high quality results prove that our approach is feasible. Besides, our proposed algorithm needs shorter time relative to other similar methods. 相似文献
7.
One novel approach for the biological delivery of peptide drugs is to incorporate the sequence of the peptide into the structure of a natural transport protein such as human serum transferrin (HST). However, a potential drawback is that the HST may increase the immunoreactivity of the peptide, in the same way that carrier proteins can be used to generate highly immunogenic peptide hapten conjugates. In this study we have generated a recombinant HST carrier protein that contains a peptide substrate of HIV-1 protease (VSQNYPIVL). The protein retained native HST function, and the peptide was surface exposed since it was immunoreactive in native dot blots, and was cleaved by HIV-1 protease. Immunisation of rabbits with the recombinant protein elicited only a very poor anti-peptide immune response. In contrast, strong anti-peptide immune responses were raised against both the peptide alone, and a chemical conjugate of the peptide with HST. These data demonstrate that it is possible to attenuate the immune response normally directed against an immunogenic peptide sequence by engineering into a surface exposed loop of HST. These findings may have an important impact on the future design of peptide delivery systems. 相似文献
8.
9.
10.