全文获取类型
收费全文 | 4403篇 |
免费 | 306篇 |
国内免费 | 135篇 |
出版年
2023年 | 46篇 |
2022年 | 56篇 |
2021年 | 101篇 |
2020年 | 84篇 |
2019年 | 130篇 |
2018年 | 117篇 |
2017年 | 112篇 |
2016年 | 107篇 |
2015年 | 109篇 |
2014年 | 196篇 |
2013年 | 225篇 |
2012年 | 165篇 |
2011年 | 244篇 |
2010年 | 146篇 |
2009年 | 239篇 |
2008年 | 228篇 |
2007年 | 235篇 |
2006年 | 221篇 |
2005年 | 245篇 |
2004年 | 207篇 |
2003年 | 165篇 |
2002年 | 147篇 |
2001年 | 99篇 |
2000年 | 90篇 |
1999年 | 103篇 |
1998年 | 91篇 |
1997年 | 84篇 |
1996年 | 111篇 |
1995年 | 100篇 |
1994年 | 72篇 |
1993年 | 75篇 |
1992年 | 67篇 |
1991年 | 43篇 |
1990年 | 32篇 |
1989年 | 23篇 |
1988年 | 30篇 |
1987年 | 22篇 |
1986年 | 10篇 |
1985年 | 28篇 |
1984年 | 78篇 |
1983年 | 28篇 |
1982年 | 27篇 |
1981年 | 25篇 |
1980年 | 15篇 |
1979年 | 19篇 |
1978年 | 7篇 |
1977年 | 18篇 |
1976年 | 7篇 |
1975年 | 5篇 |
1973年 | 3篇 |
排序方式: 共有4844条查询结果,搜索用时 15 毫秒
31.
32.
《Saudi Journal of Biological Sciences》2022,29(2):831-839
The survival reduction after transplantation limited the clinical uses of stem cells so the current study explored preconditioning adipose-derived stem cells (ADMSCs) and all-trans retinoic acid (ATRA) effects on cisplatin that caused acute kidney injury (AKI). One hundred and fifty Sprague–Dawley male rats were distributed into five groups: control group; Cisplatin (CIS) group; CIS and ATRA group; CIS and ADMSC group, and CIS, ATRA, and ADMSCs group. Ten rats were euthanized after 3rd, 7th, and 11th days from CIS injection. Renal function, molecular studies, and histopathological analysis were studied. The preconditioning of ADMSCs with ATRA increased the viability of the cells which was reflected in the amelioration of kidney functions after CIS injection by the significant reduction of serum creatinine, microalbuminuria, as well as NO, and the significant rise of creatinine clearance, as well as SOD compared to the group of cisplatin. ATRA also supported ADMSCs by a significant down-regulation of caspase-3, il-6 and TGFβ1, and a significant up-regulation of HIF1, VEGF and CD31 compared to group of cisplatin which reversed the cisplatin effect. ATRA increased renoprotective properties of ADMSCs against cisplatin- induced AKI by reducing the apoptosis, inflammation, and stimulating angiogenesis. 相似文献
33.
《Nucleosides, nucleotides & nucleic acids》2013,32(4):247-257
Synthesis and stereochemical characterization of enantiomerically pure nucleoside-3′-phosphorothioate esters and salts are reported. Vicinal carbon–phosphorus couplings reflect different predominance of the ? conformation in the isomeric (Rp and Sp) esters, while for the salts the ?t conformation prevails in both stereoisomers. The influence of solvent and temperature on the conformational preferences is also described. 相似文献
34.
35.
Ulrike Courage-Tebbe Börries Kemper 《Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression》1982,696(1):1-5
Circular double-stranded phage M13 DNA-containing gaps of defined size and location were obtained in preparative amounts by in vitro hybridization of plus- and minus-strands derived from different phage strains. 相似文献
36.
The use of 13C-NMR for studies of wheat straw decomposition 总被引:1,自引:0,他引:1
13C-NMR was used to study the field decomposition of surface retained and incorporated wheat straw. Results showed decreasing proportions of straw carbon as carbohydrate and increasing proportions of aromatic compounds during straw decomposition. These changes were greater for the surface retained straw, however greater relative microbial contamination of incorporated straw may have affected results. The cost of 13C-NMR may lessen its role in studies of this nature. 相似文献
37.
Antisense (AS) peptides complementary to the β-bulge surface loop VQGEESNDK (Boraschi loop) of the cytokine interleukin-1β (IL-1β) have been shown to bind IL-1β at the Boraschi loop position, and to inhibit some of the IL-1β-mediated biological effects in vitro. Here we show that primary AS peptide FVITFFSLY inhibits IL-1β-mediated immunostimulation in vivo in a dose-dependent fashion, while inactive on IL-1β-induced inflammation, an effect that takes place independently of the Boraschi loop. To the best of our knowledge, this is the first time that an AS peptide has been used successfully in vivo. 相似文献
38.
39.
S. Mielewczyk Z. Gdaniec G. Bobrowska R. W. Adamiak 《Nucleosides, nucleotides & nucleic acids》2013,32(1-2):273-277
Abstract Nucleophilic displacement reactions of guanosine- and inosine-derived pyridinium salts will be discussed in a view of their preparative applications in nucleoside and oligonucleotide chemistry. 相似文献
40.