全文获取类型
收费全文 | 147413篇 |
免费 | 4856篇 |
国内免费 | 5121篇 |
出版年
2024年 | 99篇 |
2023年 | 688篇 |
2022年 | 1660篇 |
2021年 | 3030篇 |
2020年 | 2074篇 |
2019年 | 2502篇 |
2018年 | 13582篇 |
2017年 | 11926篇 |
2016年 | 9611篇 |
2015年 | 4178篇 |
2014年 | 4644篇 |
2013年 | 4715篇 |
2012年 | 9315篇 |
2011年 | 17141篇 |
2010年 | 14499篇 |
2009年 | 10540篇 |
2008年 | 12481篇 |
2007年 | 13747篇 |
2006年 | 2505篇 |
2005年 | 2379篇 |
2004年 | 2448篇 |
2003年 | 2407篇 |
2002年 | 1837篇 |
2001年 | 1160篇 |
2000年 | 1046篇 |
1999年 | 833篇 |
1998年 | 507篇 |
1997年 | 475篇 |
1996年 | 486篇 |
1995年 | 422篇 |
1994年 | 419篇 |
1993年 | 355篇 |
1992年 | 466篇 |
1991年 | 361篇 |
1990年 | 291篇 |
1989年 | 267篇 |
1988年 | 227篇 |
1987年 | 207篇 |
1986年 | 176篇 |
1985年 | 154篇 |
1984年 | 122篇 |
1983年 | 139篇 |
1982年 | 83篇 |
1980年 | 52篇 |
1979年 | 63篇 |
1976年 | 46篇 |
1974年 | 54篇 |
1973年 | 45篇 |
1972年 | 299篇 |
1971年 | 300篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
231.
Albert A. Smith 《Journal of biomolecular NMR》2017,67(2):77-94
Software for fitting of NMR spectra in MATLAB is presented. Spectra are fitted in the frequency domain, using Fourier transformed lineshapes, which are derived using the experimental acquisition and processing parameters. This yields more accurate fits compared to common fitting methods that use Lorentzian or Gaussian functions. Furthermore, a very time-efficient algorithm for calculating and fitting spectra has been developed. The software also performs initial peak picking, followed by subsequent fitting and refinement of the peak list, by iteratively adding and removing peaks to improve the overall fit. Estimation of error on fitting parameters is performed using a Monte-Carlo approach. Many fitting options allow the software to be flexible enough for a wide array of applications, while still being straightforward to set up with minimal user input. 相似文献
232.
233.
234.
235.
236.
Mengnan Wang Dongjie Li Mingyue Zhang Wenzhi Yang Yali Cui Shijie Li 《Animal genetics》2015,46(4):354-360
The CDKN1C gene encodes a cyclin‐dependent kinase inhibitor and is one of the key genes involved in the development of Beckwith–Wiedemann syndrome and cancer. In this study, using a direct sequencing approach based on a single nucleotide polymorphism (SNP) at genomic DNA and cDNA levels, we show that CDKN1C exhibits monoallelic expression in all seven studied organs (heart, liver, spleen, lung, kidney, muscle and subcutaneous fat) in cattle. To investigate how methylation regulates imprinting of CDKN1C in cattle, allele‐specific methylation patterns in two putative differential methylation regions (DMRs), the CDKN1C DMR and KvDMR1, were analyzed in three tissues (liver, spleen and lung) using bisulfite sequencing PCR. Our results show that in the CDKN1C DMR both parental alleles were unmethylated in all three analyzed tissues. In contrast, KvDMR1 was differentially methylated between the two parental alleles in the same tissues. Statistical analysis showed that there is a significant difference in the methylation level between the two parental alleles (P < 0.01), confirming that this region is the DMR of KvDMR1 and that it may be correlated with CDKN1C imprinting. 相似文献
237.
238.
239.
A patent foramen ovale is a common intracardiac finding that is located between the left and right atrium. It can cause right-to-left shunting and has a high prevalence in patients who suffer a cryptogenic stroke. Earlier trials did not show superiority of percutaneous patent foramen ovale closure with standard medical therapy over standard medical therapy alone in the treatment of cryptogenic stroke. Interestingly, several meta-analyses show positive results regarding closure, suggesting underpowering of the individual trials. Recently, two large prospective trials and one long-term follow-up study showed benefit of percutaneous closure over standard medical therapy in treatment of cryptogenic stroke. A larger right-to-left shunt or the presence of an atrial septal aneurysm were predictors for a recurrent event. Therefore, percutaneous patent foramen ovale closure after cryptogenic stroke should be recommended over antiplatelet therapy alone in patients younger than 55 years of age with a high-risk patent foramen ovale. 相似文献
240.
Yoko Yamauchi Hikari Kimoto Xianyu Yang Sergey Filkin Yuri Utkin Tai Kubo 《Bioscience, biotechnology, and biochemistry》2016,80(1):158-161
Three-finger toxins (3FTxs) are one of the major components in snake venoms. In this study, we isolated a cDNA encoding a short-chain 3FTx, Pr-SNTX, from Pseudechis rossignolii. The amino acid sequence of Pr-SNTX is nearly identical to that of its ortholog in Pseudechis australis. Pr-SNTX protein inhibited muscle-type (α2βδε), but not neuronal α7 nicotinic acetylcholine receptor (nAChR) activity. 相似文献