全文获取类型
收费全文 | 377篇 |
免费 | 24篇 |
国内免费 | 33篇 |
出版年
2024年 | 4篇 |
2023年 | 9篇 |
2022年 | 22篇 |
2021年 | 24篇 |
2020年 | 16篇 |
2019年 | 15篇 |
2018年 | 12篇 |
2017年 | 8篇 |
2016年 | 12篇 |
2015年 | 27篇 |
2014年 | 29篇 |
2013年 | 27篇 |
2012年 | 19篇 |
2011年 | 23篇 |
2010年 | 17篇 |
2009年 | 14篇 |
2008年 | 14篇 |
2007年 | 12篇 |
2006年 | 14篇 |
2005年 | 9篇 |
2004年 | 9篇 |
2003年 | 6篇 |
2002年 | 5篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 5篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 12篇 |
1984年 | 12篇 |
1983年 | 5篇 |
1982年 | 10篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 6篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1951年 | 1篇 |
1932年 | 1篇 |
排序方式: 共有434条查询结果,搜索用时 18 毫秒
91.
Xiaolu Zhou 《PloS one》2015,10(10)
The growing number of bike sharing systems (BSS) in many cities largely facilitates biking for transportation and recreation. Most recent bike sharing systems produce time and location specific data, which enables the study of travel behavior and mobility of each individual. However, despite a rapid growth of interest, studies on massive bike sharing data and the underneath travel pattern are still limited. Few studies have explored and visualized spatiotemporal patterns of bike sharing behavior using flow clustering, nor examined the station functional profiles based on over-demand patterns. This study investigated the spatiotemporal biking pattern in Chicago by analyzing massive BSS data from July to December in 2013 and 2014. The BSS in Chicago gained more popularity. About 15.9% more people subscribed to this service. Specifically, we constructed bike flow similarity graph and used fastgreedy algorithm to detect spatial communities of biking flows. By using the proposed methods, we discovered unique travel patterns on weekdays and weekends as well as different travel trends for customers and subscribers from the noisy massive amount data. In addition, we also examined the temporal demands for bikes and docks using hierarchical clustering method. Results demonstrated the modeled over-demand patterns in Chicago. This study contributes to offer better knowledge of biking flow patterns, which was difficult to obtain using traditional methods. Given the trend of increasing popularity of the BSS and data openness in different cities, methods used in this study can extend to examine the biking patterns and BSS functionality in different cities. 相似文献
92.
Quantitative Proteomics Identified TTC4 as a TBK1 Interactor and a Positive Regulator of SeV‐Induced Innate Immunity
下载免费PDF全文
![点击此处可从《Proteomics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jun Shang Tian Xia Qiang‐Qiang Han Xiaolu Zhao Ming‐Ming Hu Hong‐Bing Shu Lin Guo 《Proteomics》2018,18(2)
TBK1, STING, and MDA5 are important players within the antiviral innate immune response network. We mapped the interactome of endogenous TBK1, STING, and MDA5 by affinity enrichment MS in virally infected or uninfected THP‐1 cells. Based on quantitative data of more than 2000 proteins and stringent statistical analysis, 58 proteins were identified as high‐confidence interactors for at least one of three bait proteins. Our data indicated that TBK1 and MDA5 mostly interacted within preexisting protein networks, while STING interacted with different proteins with different viral infections. Functional analysis was performed on 17 interactors, and six were found to have functions in innate immune responses. We identified TTC4 as a TBK1 interactor and positive regulator of sendai virus‐induced innate immunity. 相似文献
93.
Comparative Proteome Analysis Reveals that Cuticular Proteins Analogous to Peritrophin‐Motif Proteins are Involved in the Regeneration of Chitin Layer in the Silk Gland of Bombyx mori at the Molting Stage
下载免费PDF全文
![点击此处可从《Proteomics》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Xiaolu Zhang Huaipu Chang Zhaoming Dong Yan Zhang Dongchao Zhao Lin Ye Qingyou Xia Ping Zhao 《Proteomics》2018,18(19)
The silk gland of silkworm produces silk proteins during larval development. Many studies have long focused on the silk gland of the fifth instar larvae, but few have investigated this gland at other larval stages. In the present study, the silk gland proteomes of the fourth instar and fourth molt are analyzed using liquid chromatography–tandem mass spectrometry. In total, 2654 proteins are identified from the silk gland. A high abundance of ribosomal proteins and RR‐motif chitin‐binding proteins is identified during day 2 of the fourth instar (IV‐2) larval developmental stage, and the expression of cuticular proteins analogous to peritrophin (CPAP)‐motif chitin‐binding proteins is higher during the fourth molt (IV‐M). In all, nine enzymes are found to be involved in the chitin regeneration pathway in the silk gland. Among them, two chitinase and two chitin deacetylases are identified as CPAP‐motif proteins. Furthermore, the expression of CPAP3‐G, the most abundant CPAP‐motif cuticular protein in the silk gland during the IV‐M stage, is investigated using western blot and immunofluorescence analyses; CPAP3‐G shows a reverse changing trend with chitin in the silk gland. The findings of this study suggest that CPAP‐motif chitin‐binding proteins are involved in the degradation of the chitin layer in the silk gland. The data have been deposited to the ProteomeXchange with identifier PXD008677. 相似文献
94.
Microscopic insight into the DNA condensation process of a zwitterion‐functionalized polycation
下载免费PDF全文
![点击此处可从《Biopolymers》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Zwitterion‐functionalized polycations are ideal gene carriers with long circulation, high cellular uptaking and low cell viability. However, the trade‐off between the DNA condensation efficiency and the cell viability must be addressed. The purpose of this study is to provide a microscopic insight into the DNA condensation process and to explore the effect of a zwitterionic block of zwitterion‐functionalized polycation, which is of great significance in designing novel gene delivery systems. Poly[2‐(dimethylamino)ethyl methacrylate‐b‐(sulfobetaine methacrylate)] (PDMAEMA‐b‐PSBMA) copolymers were synthesized and used as the model systems. Different from the conventional concept that the PSBMA zwitterionic block act only as the “stealthy” groups, the subtle differences in physical and colloidal characteristics between the polycation/DNA polyplexes show that the PSBMA segment is capable of wrapping DNA attributed to the quaternary ammonium cations, without compromising the DNA condensation capability. On the other hand, the incorporation of PSBMA block reduces the surface charge of the polyplexes, which substantially result in the inefficient transfection and the reduced cytotoxicity. 相似文献
95.
96.
97.
Morphological variation in color of female cones in white fir, Abies concolor, is postulated to have adaptive value. The purple variant is only found in one part of the range of white fir where it grows at high elevations. In addition, the frequency of purple cones increases with increasing elevation, suggesting a thermoregulatory function for the purple variant in the cold habitats found at high elevations. Temperature measurements support this hypothesis: purple cones attain higher internal temperatures than do green cones of comparable size. Cone diameter may, in fact, be correlated with cone color but definitive evidence is lacking. Alternative hypotheses are offered which may also be important in maintaining the presence of the purple variant at high elevations. It is suggested that other characters associated with purple cones may place them at a competitive disadvantage at lower elevations. 相似文献
98.
99.
Huimin Xu Huasheng Wang Qianqian Xu Le Lv Chunhua Yin Xiaolu Liu Hongwu Du Hai Yan 《PloS one》2015,10(4)
Harmful cyanobacterial blooms in waters have become a global environmental problem, this mainly due to the production and release of various microalgal toxins, in which microcystins (MCs) are distributed widely. Here, we focused on the study of a typical form of microcystins called microcystin-YR (MC-YR). It was found that initial 14.8 mg/L of MC-YR could be completely eliminated within 10 hr by the crude enzymes (CEs) of Sphingopyxis sp. USTB-05, a promising bacterial strain we isolated and identified in our previous study. During the enzymatic biodegradation of MC-YR with time course, the peaks of two intermediate and two final products were observed on the profiles of HPLC at the wavelengths of 238 nm and 230 nm, respectively. Based on the analysis of m/z ratios of MC-YR and its four products by LC-MS/MS, we suggested that at least four enzymes were involved in the biodegradation of MC-YR by Sphingopyxis sp. USTB-05. The first enzyme microcystinase converted cyclic MC-YR to linear MC-YR as the first product. Then the second enzyme serine protease was found to cleave the target peptide bond between alanine (Ala) and tyrosine (Tyr) of linearized MC-YR, producing a tetrapeptide and a tripeptide as second products, which were Adda-Glu-Mdha-Ala and Tyr-Masp-Arg, respectively. Next, the third enzyme peptidase converted the tetrapeptide of Adda-Glu-Mdha-Ala to Adda. And the fourth enzyme cleaved the tripeptide of Tyr-Masp-Arg to produce Tyr and dipeptide (Masp-Arg), which has never been reported. These findings will help us better understand the biodegradation pathway of MC-YR by Sphingopyxis sp. USTB-05. 相似文献
100.
Summary Protein A has been covalently coupled to a water soluble galactomannan bearing aldehyde groups, introduced by oxidation with D-galactose oxidase. The soluble conjugate has been used to form complexes with immunoglobulin G, precipitation being induced by the formation of polysaccharide-borate complexes. After recovery of the immunoglobulin, the polysaccharide-protein A conjugates can be re-cycled and used for further isolations. 相似文献