全文获取类型
收费全文 | 5053篇 |
免费 | 368篇 |
国内免费 | 3篇 |
出版年
2024年 | 4篇 |
2023年 | 19篇 |
2022年 | 60篇 |
2021年 | 92篇 |
2020年 | 75篇 |
2019年 | 97篇 |
2018年 | 144篇 |
2017年 | 107篇 |
2016年 | 176篇 |
2015年 | 257篇 |
2014年 | 330篇 |
2013年 | 359篇 |
2012年 | 463篇 |
2011年 | 449篇 |
2010年 | 274篇 |
2009年 | 249篇 |
2008年 | 317篇 |
2007年 | 315篇 |
2006年 | 248篇 |
2005年 | 233篇 |
2004年 | 251篇 |
2003年 | 193篇 |
2002年 | 164篇 |
2001年 | 102篇 |
2000年 | 104篇 |
1999年 | 68篇 |
1998年 | 26篇 |
1997年 | 26篇 |
1996年 | 20篇 |
1995年 | 18篇 |
1994年 | 15篇 |
1993年 | 11篇 |
1992年 | 19篇 |
1991年 | 24篇 |
1990年 | 18篇 |
1989年 | 10篇 |
1988年 | 13篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 7篇 |
1982年 | 5篇 |
1980年 | 5篇 |
1978年 | 3篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1973年 | 4篇 |
1972年 | 3篇 |
1971年 | 5篇 |
1967年 | 3篇 |
排序方式: 共有5424条查询结果,搜索用时 31 毫秒
831.
Byung-Ha Oh Suhng Wook Kim Seong-Eon Ryu Sang-Soo Kim Mi-Kyung Yoon Kwan Yong Choi 《Proteins》1996,24(4):514-515
The Δ5-3-ketosteroid isomerase from Pseudomonas putida biotype B has been crystallized. The crystals belong to the space group P212121 with unit cell dimensions of a = 36.48 Å, b = 74.30 Å, c = 96.02 Å, and contain one homodimer per asymmetric unit. Native diffraction data to 2.19 Å resolution have been obtained from one crystal at room temperature indicating that the crystals are quite suitable for structure determination by multiple isomorphous replacement. 相似文献
832.
Tu Cam Le Chae-Yoon Yim Songhee Park Nikita Katila Inho Yang Myoung Chong Song Yeo Joon Yoon Dong-Young Choi Hyukjae Choi Sang-Jip Nam William Fenical 《Bioorganic & medicinal chemistry letters》2017,27(14):3123-3126
HPLC-UV guided isolation of the culture broth of a marine bacterium Saccharomonospora sp. CNQ-490 has led to the isolation of two new natural products, lodopyridones B and C (1 and 2) along with the previously reported lodopyridone A (3). Their chemical structures were established from the interpretation of 2D NMR spectroscopic data and the comparison of NMR data with the lodopyridone A (3). Lodopyridones B and C (1 and 2) possess the thiazole, and chloroquinoline groups which are characteristic features of these molecules. Lodopyridones A–C show weak inhibitory activities on the β-site amyloid precursor protein cleaving enzyme 1 (BACE1). 相似文献
833.
Yelin Kang Bong-Gyu Kim Sunghoon Kim Youngshim Lee Youngdae Yoon 《Bioorganic & medicinal chemistry letters》2017,27(3):420-426
Many membrane-associated proteins are involved in various signaling pathways, including the phosphoinositide 3-kinase (PI3K) pathway, which has key roles in diverse cellular processes. Disruption of the activities of these proteins is involved in the development of disease in humans, making these proteins promising targets for drug development. In most cases, the catalytic domain is targeted; however, it is also possible to target membrane associations in order to regulate protein activity. In this study, we established a novel method to study protein-lipid interactions and screened for flavonoid-derived antagonists of PtdIns(3,4,5)P3 binding with the phosphoinositide-dependent kinase 1 (PDK1) pleckstrin homology (PH) domain. Using an enhanced green fluorescent protein (eGFP)-tagged PDK1 PH domain and 50% sucrose-loaded liposomes, the protein-lipid interaction could be efficiently evaluated using liposome pull-down assays coupled with fluorescence spectrophotometry, and a total of 32 flavonoids were screened as antagonists for PtdIns(3,4,5)P3 binding with the PDK1 PH domain. From this analysis, we found that two adjunct hydroxyl groups in the C ring were responsible for the inhibitory effects of the flavonoids. Because the flavonoids shared structural similarities, the results were then subjected to quantitative structure-activity relationship (QSAR) analysis. The results were then further confirmed by in silico docking experiments. Taken together, our strategy presented herein to screen antagonists targeting lipid-protein interactions could be an alternative method for identification and characterization of drug candidates. 相似文献
834.
The Ginsenoside Derivative 20(S)‐Protopanaxadiol Inhibits Solar Ultraviolet Light‐Induced Matrix Metalloproteinase‐1 Expression
下载免费PDF全文
![点击此处可从《Journal of cellular biochemistry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
835.
Simulating the fidelity and the three Mg mechanism of pol η and clarifying the validity of transition state theory in enzyme catalysis
下载免费PDF全文
![点击此处可从《Proteins》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Pol η belongs to the important Y family of DNA polymerases that can catalyze translesion synthesis across sites of damaged DNA. This activity involves the reduced fidelity of Pol η for 8‐oxo‐7,8‐dhyedro‐2′‐deoxoguanosin(8‐oxoG). The fundamental interest in Pol η has grown recently with the demonstration of the importance of a 3rd Mg2+ ion. The current work explores both the fidelity of Pol η and the role of the 3rd metal ion, by using empirical valence bond (EVB) simulations. The simulations reproduce the observed trend in fidelity and shed a new light on the role of the 3rd metal ion. It is found that this ion does not lead to a major catalytic effect, but most probably plays an important role in reducing the product release barrier. Furthermore, it is concluded, in contrast to some implications, that the effect of this metal does not violate transition state theory, and the evaluation of the catalytic effect must conserve the molecular composition upon moving from the reactant to the transition state. Proteins 2017; 85:1446–1453. © 2017 Wiley Periodicals, Inc. 相似文献
836.
837.
Soowan Kim Minhyung Jung Yoon‐Jae Song Se Chan Kang BaeYong Kim I‐Jin Choi Hong Geun Kim Doo‐Hyung Lee 《Entomological Research》2017,47(3):208-216
The sweetpotato whitefly, Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae), is a major pest on greenhouse crops including sweet pepper (Capsicum annuum L.), which is one of the leading greenhouse crops in South Korea. Synthetic insecticides, especially the neonicotinoids, have been used to conventionally control this pest. There have been continuous efforts to develop plant‐derived compounds as insecticides, deterrents, and repellents to reduce spraying synthetic insecticides. To develop new plant‐extract insecticides, we investigated the insecticidal effects of Perilla sp. (Perilla frutescens var. crispa) extract on B. tabaci in laboratory conditions. The Perilla sp. extract induced 90 % mortality within one hour, but phytotoxicity symptoms on sweet pepper leaves were also observed. We monitored the population change and spatial distribution of adult B. tabaci in an experimental sweet pepper greenhouse using yellow sticky traps, and analyzed distribution patterns by spatial analysis with distance indices (SADIE). Based on monitoring data and SADIE analysis, we concluded that B. tabaci aggregated near the greenhouse entrances, and it showed aggregation and association pattern as time passed. Therefore, we recommend spraying Perilla sp. extract near the entrances or wild host before the pest population penetrates. It will be one of the alternative pest management strategies to reduce B. tabaci population with fewer negative effects from chemical insecticide. Further study is required to reduce the phytotoxicity symptoms from Perilla sp. extract spray and insecticidal effect should be evaluated under field conditions. 相似文献
838.
Nanogenerators: Boosting Power‐Generating Performance of Triboelectric Nanogenerators via Artificial Control of Ferroelectric Polarization and Dielectric Properties (Adv. Energy Mater. 2/2017)
下载免费PDF全文
![点击此处可从《Liver Transplantation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
839.
Li‐Ion Cells: Surface Engineering Strategies of Layered LiCoO2 Cathode Material to Realize High‐Energy and High‐Voltage Li‐Ion Cells (Adv. Energy Mater. 1/2017)
下载免费PDF全文
![点击此处可从《Liver Transplantation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
840.
Yoon Jeong Lee Han-Gyu Bae Hyung-Bae Jeon Dong-Young Kim 《Animal cells and systems.》2017,21(5):349-357
Endemic species typically have a narrow niche breadth, and are likely more vulnerable to extinction than more widespread taxa. Squalidus multimaculatus is a small cyprinid endemic to the Korean Peninsula, and its reported geographical range was restricted to several small rivers located along the southeast coast. Several populations of S. multimaculatus have supposedly been subject to a variety of recent anthropogenic actions. Here, we analyzed the pattern of genetic diversity within and among populations of S. multimaculatus using nine microsatellite loci to quantify the relative contributions of human-mediated processes to the contemporary distribution and genetic structure. Overall, low levels of genetic diversity were exhibited in the populations of S. multimaculatus. Genetic differentiations among populations were not completely represented by their geographical proximity, likely resulting from the low intrapopulation genetic variability and anthropogenic transplants. The most conspicuous outcome of the anthropogenic activities was the introgression of alleles from a closely related species, S. gracilis majimae. Our study showed that anthropogenic transplanting, even with only a small number of individuals, can challenge our conservation goal to maintain the species integrity that has long been shaped in evolutionary processes. 相似文献