全文获取类型
收费全文 | 9528篇 |
免费 | 945篇 |
国内免费 | 4篇 |
出版年
2021年 | 154篇 |
2020年 | 89篇 |
2019年 | 100篇 |
2018年 | 118篇 |
2017年 | 95篇 |
2016年 | 193篇 |
2015年 | 352篇 |
2014年 | 366篇 |
2013年 | 526篇 |
2012年 | 643篇 |
2011年 | 630篇 |
2010年 | 356篇 |
2009年 | 341篇 |
2008年 | 522篇 |
2007年 | 537篇 |
2006年 | 443篇 |
2005年 | 414篇 |
2004年 | 407篇 |
2003年 | 414篇 |
2002年 | 419篇 |
2001年 | 148篇 |
2000年 | 144篇 |
1999年 | 123篇 |
1998年 | 141篇 |
1997年 | 91篇 |
1996年 | 102篇 |
1995年 | 74篇 |
1994年 | 98篇 |
1993年 | 81篇 |
1992年 | 93篇 |
1991年 | 88篇 |
1990年 | 102篇 |
1989年 | 85篇 |
1988年 | 90篇 |
1987年 | 69篇 |
1986年 | 69篇 |
1985年 | 84篇 |
1984年 | 85篇 |
1983年 | 87篇 |
1982年 | 81篇 |
1981年 | 96篇 |
1980年 | 69篇 |
1979年 | 67篇 |
1978年 | 71篇 |
1977年 | 70篇 |
1976年 | 70篇 |
1975年 | 63篇 |
1974年 | 75篇 |
1973年 | 61篇 |
1969年 | 49篇 |
排序方式: 共有10000条查询结果,搜索用时 718 毫秒
1.
2.
3.
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4.
5.
Jin Wei Mia Madel Alfajaro Peter C. DeWeirdt Ruth E. Hanna William J. Lu-Culligan Wesley L. Cai Madison S. Strine Shang-Min Zhang Vincent R. Graziano Cameron O. Schmitz Jennifer S. Chen Madeleine C. Mankowski Renata B. Filler Neal G. Ravindra Victor Gasque Fernando J. de Miguel Ajinkya Patil Huacui Chen Craig B. Wilen 《Cell》2021,184(1):76-91.e13
- Download : Download high-res image (212KB)
- Download : Download full-size image
6.
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
7.
8.
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9.
Ruth C. Paul B. Rainey Brian J. Sheehan Orla M. Keane Charles J. Dorman 《Current biology : CB》1999,9(24)
The relationship between environment and mutation is complex [1]. Claims of Lamarkian mutation [2] have proved unfounded [3], [4] and [5]; it is apparent, however, that the external environment can influence the generation of heritable variation, through either direct effects on DNA sequence [6] or DNA maintenance and copying mechanisms [7], [8], [9] and [10], or as a consequence of evolutionary processes [11], [12], [13], [14], [15] and [16]. The spectrum of mutational events subject to environmental influence is unknown [6] and precisely how environmental signals modulate mutation is unclear. Evidence from bacteria suggests that a transient recombination-dependent hypermutational state can be induced by starvation [5]. It is also apparent that chnages in the mutability of specific loci can be influenced by alterations in DNA topology [10] and [17]. Here we describe a remarkable instance of adaptive evolution in Salmonella which is caused by a mutation that occurs in intermediate-strength osmotic environments. We show that the mutation is not ‘directed’ and describe its genetic basis. We also present compelling evidence in support of the hypothesis that the mutational event is constrained by signals transmitted from the external environment via changes in the activity of DNA gyrase. 相似文献
10.