全文获取类型
收费全文 | 10416篇 |
免费 | 996篇 |
国内免费 | 71篇 |
专业分类
11483篇 |
出版年
2023年 | 70篇 |
2022年 | 117篇 |
2021年 | 235篇 |
2020年 | 154篇 |
2019年 | 213篇 |
2018年 | 229篇 |
2017年 | 234篇 |
2016年 | 299篇 |
2015年 | 500篇 |
2014年 | 506篇 |
2013年 | 659篇 |
2012年 | 766篇 |
2011年 | 744篇 |
2010年 | 499篇 |
2009年 | 482篇 |
2008年 | 572篇 |
2007年 | 513篇 |
2006年 | 446篇 |
2005年 | 417篇 |
2004年 | 428篇 |
2003年 | 359篇 |
2002年 | 370篇 |
2001年 | 149篇 |
2000年 | 146篇 |
1999年 | 117篇 |
1998年 | 103篇 |
1997年 | 83篇 |
1996年 | 89篇 |
1995年 | 71篇 |
1994年 | 78篇 |
1993年 | 78篇 |
1992年 | 88篇 |
1991年 | 87篇 |
1990年 | 95篇 |
1989年 | 84篇 |
1988年 | 76篇 |
1987年 | 67篇 |
1986年 | 58篇 |
1985年 | 73篇 |
1984年 | 77篇 |
1983年 | 65篇 |
1982年 | 65篇 |
1981年 | 71篇 |
1980年 | 52篇 |
1979年 | 59篇 |
1978年 | 56篇 |
1977年 | 56篇 |
1976年 | 48篇 |
1975年 | 46篇 |
1974年 | 53篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
Mandana Nikpour Dafna D Gladman Dominique Ibanez Paula J Harvey Murray B Urowitz 《Arthritis research & therapy》2010,12(3):R125
Introduction
Total cholesterol (TC) and blood pressure (BP) are likely to take a dynamic course over time in patients with systemic lupus erythematosus (SLE). This would have important implications in terms of using single-point-in-time measurements of these variables to assess coronary artery disease (CAD) risk. The objective of this study was to describe and quantify variability over time of TC and BP among patients with SLE and to determine their correlates. 相似文献3.
The physical and covalent binding of the carcinogen benzo(a)pyrene-7,8-diol-9,10-oxide (BaPDE) to poly(dG-dC).(dG-dC) and poly(dG-m5dC).(dG-m5dC) in the B and Z forms were studied utilizing absorbance, fluorescence and linear dichroism techniques. In the case of poly(dG-dC).(dG-dC) the decrease in the covalent binding of BaPDE with increasing NaCl concentration (0.1-4 M) as the B form is transformed to the Z form is attributed to the effects of high ionic strengths on the reactivity and physical binding of BaPDE to the polynucleotides; these effects tend to obscure differences in reactivities with the B and Z forms of the nucleic acids. In the case of poly(dG-m5dC).(dG-m5dC) the B-to-Z transition is induced at low ionic strength (2 mM NaCl + 10 microM Co(NH3)6Cl3) and the covalent binding is found to be 2-3-times lower to the Z form than to the B form. Physical binding of BaPDE by intercalation, which precedes the covalent binding reaction, is significantly lower in the Z form than in the B form, thus accounting, in part, for the lower covalent binding. The linear dichroism characteristics of BaPDE covalently bound to the Z and B forms of poly(dG-m5dC).(dG-m5dC) are consistent with nonintercalative, probably external conformations of the aromatic pyrenyl residues. 相似文献
4.
Background
Radial chromosome positioning in interphase nuclei is nonrandom and can alter according to developmental, differentiation, proliferation, or disease status. However, it is not yet clear when and how chromosome repositioning is elicited. 相似文献5.
D. S. Coffman Ben H. Leichtling H. V. Rickenberg 《Journal of cellular biochemistry》1981,15(4):369-385
The phosphoproteins of Dictyostelium discoideum were compared at different stages of development by polyacrylamide gel electrophoresis. Certain phosphoproteins of vegetative amoebae were conserved while others appeared and disappeared during development. Four major phosphoproteins with apparent subunit molecular weights of 50,000, 47,000, 38,000, and 34,000 disappeared precociously in response to exogenous cAMP. Two membranal phosphoproteins, with apparent subunit molecular weights of 80,000 and 81,000, appeared precociously in response to added cAMP. One of these phosphoproteins, molecular weight of 80,000, has been identified tentatively as the “contact site A” glycoprotein. Another membranal protein, with apparent subunit molecular weight of 42,000, unaffected in its appearance by cAMP, has been identified tentatively as phosphoactin. 相似文献
6.
7.
8.
9.
10.
Xu Liu Ben Chen Lulan Chen Wan-Ting Ren Juan Liu Guoxiang Wang Wei Fan Xin Wang Yun Wang 《PloS one》2013,8(4)
Phenol red is widely used in cell culture as a pH indicator. Recently, it also has been reported to have estrogen-like bioactivity and be capable of promoting cell proliferation in different cell lines. However, the effect of phenol red on primary neuronal culture has never been investigated. By using patch clamp technique, we demonstrated that hippocampal pyramidal neurons cultured in neurobasal medium containing no phenol red had large depolarization-associated epileptiform bursting activities, which were rarely seen in neurons cultured in phenol red-containing medium. Further experiment data indicate that the suppressive effect of the phenol red on the abnormal epileptiform burst neuronal activities was U-shape dose related, with the most effective concentration at 28 µM. In addition, this concentration related inhibitory effect of phenol red on the epileptiform neuronal discharges was mimicked by 17-β-estradiol, an estrogen receptor agonist, and inhibited by ICI-182,780, an estrogen receptor antagonist. Our results suggest that estrogen receptor activation by phenol red in the culture medium prevents formation of abnormal, epileptiform burst activity. These studies highlight the importance of phenol red as estrogen receptor stimulator and cautions of careful use of phenol red in cell culture media. 相似文献