全文获取类型
收费全文 | 56818篇 |
免费 | 5704篇 |
国内免费 | 3061篇 |
出版年
2024年 | 68篇 |
2023年 | 480篇 |
2022年 | 1249篇 |
2021年 | 2337篇 |
2020年 | 1511篇 |
2019年 | 1897篇 |
2018年 | 2001篇 |
2017年 | 1436篇 |
2016年 | 2032篇 |
2015年 | 2855篇 |
2014年 | 3391篇 |
2013年 | 3715篇 |
2012年 | 4291篇 |
2011年 | 3999篇 |
2010年 | 2487篇 |
2009年 | 2106篇 |
2008年 | 2569篇 |
2007年 | 2315篇 |
2006年 | 2164篇 |
2005年 | 1794篇 |
2004年 | 1525篇 |
2003年 | 1384篇 |
2002年 | 1211篇 |
2001年 | 2832篇 |
2000年 | 2617篇 |
1999年 | 2033篇 |
1998年 | 757篇 |
1997年 | 800篇 |
1996年 | 716篇 |
1995年 | 654篇 |
1994年 | 583篇 |
1993年 | 478篇 |
1992年 | 1003篇 |
1991年 | 810篇 |
1990年 | 698篇 |
1989年 | 563篇 |
1988年 | 427篇 |
1987年 | 329篇 |
1986年 | 265篇 |
1985年 | 216篇 |
1984年 | 142篇 |
1983年 | 116篇 |
1982年 | 77篇 |
1981年 | 50篇 |
1980年 | 35篇 |
1979年 | 41篇 |
1978年 | 27篇 |
1976年 | 31篇 |
1973年 | 30篇 |
1970年 | 24篇 |
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
71.
Plasmonics - We investigate aluminum nanopatch/nanohole arrays surrounded by a dielectric material on plastic substrates for large area color printing. In this specific arrangement, metallic... 相似文献
72.
73.
74.
75.
A. Benito E. Viaplana J.L. Corchero X. Carbonell A. Villaverde 《FEMS microbiology letters》1995,129(2-3):157-162
Abstract The 3D gene of foot-and-mouth disease virus encodes the viral RNA dependent RNA polymerase, also called virus infection associated (VIA) antigen, which is the most important serological marker of virus infection. This 3D gene from a serotype Cl virus has been cloned and overexpressed in Escherichia coli under the control of the strong lambda lytic promoters. The resulting 51 kDa recombinant protein has been shown to be immunoreactive with sera from infected animals. After induction of gene expression, an immediate and dramatic arrest of cell DNA synthesis occurs, similar to that produced by genotoxic doses of the drug mitomycin C. This effect does not occur during the production of either a truncated VIA antigen or other related and non-related viral proteins. The inhibition of DNA replication results in a subsequent induction of the host SOS DNA-repair response and in an increase of the mutation frequency in the surviving cells. 相似文献
76.
77.
Aurin tricarboxylic acid, the anti-AIDS compound, prevents the binding of interferon-alpha to its receptor 总被引:2,自引:0,他引:2
Y X Gan J L Weaver P S Pine K C Zoon A Aszalos 《Biochemical and biophysical research communications》1990,172(3):1298-1303
Binding of HIV to its receptor, the CD4 molecule of lymphocytes, can be prevented by chemical agents. These agents could be considered as potential anti-AIDS drugs. We have shown that aurin tricarboxylic acid (ATA, 3 microM) specifically blocks the binding of gp120, the HIV coat protein, to the CD4 molecule. We have also found that ATA prevents the binding of interferon-alpha to its receptor in a dose-dependent manner (12-50 microM range). Membrane potential shift, associated with binding of interferon-alpha to its receptor, was also blocked by ATA in a dose-dependent fashion. Our results indicate that potential anti-AIDS drugs should be screened for such undesired side effects. 相似文献
78.
79.
Genome‐wide detection of CNVs associated with beak deformity in chickens using high‐density 600K SNP arrays
下载免费PDF全文
![点击此处可从《Animal genetics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
H. Bai Y. Sun N. Liu Y. Liu F. Xue Y. Li S. Xu A. Ni J. Ye Y. Chen J. Chen 《Animal genetics》2018,49(3):226-236
Beak deformity (crossed beaks) is found in several indigenous chicken breeds including Beijing‐You studied here. Birds with deformed beaks have reduced feed intake and poor production performance. Recently, copy number variation (CNV) has been examined in many species and is recognized as a source of genetic variation, especially for disease phenotypes. In this study, to unravel the genetic mechanisms underlying beak deformity, we performed genome‐wide CNV detection using Affymetrix chicken high‐density 600K data on 48 deformed‐beak and 48 normal birds using penncnv . As a result, two and eight CNV regions (CNVRs) covering 0.32 and 2.45 Mb respectively on autosomes were identified in deformed‐beak and normal birds respectively. Further RT‐qPCR studies validated nine of the 10 CNVRs. The ratios of six CNVRs were significantly different between deformed‐beak and normal birds (P < 0.01). Within these six regions, three and 21 known genes were identified in deformed‐beak and normal birds respectively. Bioinformatics analysis showed that these genes were enriched in six GO terms and one KEGG pathway. Five candidate genes in the CNVRs were further validated using RT‐qPCR. The expression of LRIG2 (leucine rich repeats and immunoglobulin like domains 2) was lower in birds with deformed beaks (P < 0.01). Therefore, the LRIG2 gene could be considered a key factor in view of its known functions and its potential roles in beak deformity. Overall, our results will be helpful for future investigations of the genomic structural variations underlying beak deformity in chickens. 相似文献
80.
This paper studies a Non-convex State-dependent Linear Quadratic Regulator (NSLQR) problem, in which the control penalty weighting matrix in the performance index is state-dependent. A necessary and sufficient condition for the optimal solution is established with a rigorous proof by Euler-Lagrange Equation. It is found that the optimal solution of the NSLQR problem can be obtained by solving a Pseudo-Differential-Riccati-Equation (PDRE) simultaneously with the closed-loop system equation. A Comparison Theorem for the PDRE is given to facilitate solution methods for the PDRE. A linear time-variant system is employed as an example in simulation to verify the proposed optimal solution. As a non-trivial application, a goal pursuit process in psychology is modeled as a NSLQR problem and two typical goal pursuit behaviors found in human and animals are reproduced using different control weighting . It is found that these two behaviors save control energy and cause less stress over Conventional Control Behavior typified by the LQR control with a constant control weighting , in situations where only the goal discrepancy at the terminal time is of concern, such as in Marathon races and target hitting missions. 相似文献