全文获取类型
收费全文 | 4958篇 |
免费 | 419篇 |
国内免费 | 470篇 |
专业分类
5847篇 |
出版年
2024年 | 44篇 |
2023年 | 70篇 |
2022年 | 150篇 |
2021年 | 208篇 |
2020年 | 203篇 |
2019年 | 235篇 |
2018年 | 186篇 |
2017年 | 155篇 |
2016年 | 221篇 |
2015年 | 275篇 |
2014年 | 368篇 |
2013年 | 373篇 |
2012年 | 414篇 |
2011年 | 359篇 |
2010年 | 246篇 |
2009年 | 245篇 |
2008年 | 287篇 |
2007年 | 244篇 |
2006年 | 235篇 |
2005年 | 178篇 |
2004年 | 189篇 |
2003年 | 169篇 |
2002年 | 162篇 |
2001年 | 81篇 |
2000年 | 69篇 |
1999年 | 65篇 |
1998年 | 52篇 |
1997年 | 51篇 |
1996年 | 41篇 |
1995年 | 25篇 |
1994年 | 20篇 |
1993年 | 18篇 |
1992年 | 39篇 |
1991年 | 29篇 |
1990年 | 13篇 |
1989年 | 15篇 |
1988年 | 9篇 |
1987年 | 15篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 10篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1970年 | 4篇 |
1968年 | 8篇 |
1967年 | 4篇 |
1966年 | 6篇 |
1965年 | 5篇 |
1964年 | 3篇 |
排序方式: 共有5847条查询结果,搜索用时 93 毫秒
21.
Genotyping over 100,000 SNPs on a pair of oligonucleotide arrays 总被引:1,自引:0,他引:1
Matsuzaki H Dong S Loi H Di X Liu G Hubbell E Law J Berntsen T Chadha M Hui H Yang G Kennedy GC Webster TA Cawley S Walsh PS Jones KW Fodor SP Mei R 《Nature methods》2004,1(2):109-111
We present a genotyping method for simultaneously scoring 116,204 SNPs using oligonucleotide arrays. At call rates >99%, reproducibility is >99.97% and accuracy, as measured by inheritance in trios and concordance with the HapMap Project, is >99.7%. Average intermarker distance is 23.6 kb, and 92% of the genome is within 100 kb of a SNP marker. Average heterozygosity is 0.30, with 105,511 SNPs having minor allele frequencies >5%. 相似文献
22.
Roth DM Lai NC Gao MH Drumm JD Jimenez J Feramisco JR Hammond HK 《American journal of physiology. Heart and circulatory physiology》2004,287(1):H172-H177
We performed indirect intracoronary delivery of adenovirus vectors in mice and explored techniques including hypothermia and pharmacological means to increase cardiac gene transfer. Mice were maintained in a normothermic state or cooled to 25 degrees C. The aorta or both the pulmonary artery and aorta were clamped while a needle was advanced into the left ventricular cavity to deliver adenovirus vectors encoding enhanced green fluorescent protein (EGFP) or murine adenylyl cyclase type VI (AC(VI)) with saline, sodium nitroprusside, acetylcholine, or serotonin. Clamping was maintained for 30 s (normothermia) or 2 min (25 degrees C) after adenovirus administration. Mice were killed 7 or 21 days later, and hearts were examined for EGFP expression. Compared with clamping the aorta alone and with no cooling, gene transfer was increased as follows: 1) 1.3-fold with hypothermia to extend dwell time; 2) 4.5-fold by clamping the aorta and the pulmonary artery; 3) 11.4-fold with nitroprusside administration; 4) 11.8-fold with serotonin addition, and 5) 14.3-fold with acetylcholine delivery. Gene expression remained substantial at 21 days, and no significant inflammatory response was seen. Efficacy of the method was tested by performing gene transfer of adenovirus encoding AC(VI). Fourteen days after gene transfer, hearts isolated from mice that received adenovirus encoding AC(VI) showed increased contractile function. Indirect intracoronary delivery of adenovirus vectors in mice is associated with efficient cardiac gene transfer and increased left ventricular function after AC(VI) gene transfer. 相似文献
23.
Yuxin Wu Lei Wang Chen Lin Yan Lin Mei Zhou Liang Chen Brian Connolly Yingqi Zhang Tianbao Chen Chris Shaw 《PloS one》2013,8(2)
The defensive skin secretions of amphibians are a rich resource for the discovery of novel, bioactive peptides. Here we report the identification of a novel vascular smooth muscle-relaxing peptide, named vasorelaxin, from the skin secretion of the Chinese piebald odorous frog, Odorrana schmackeri. Vasorelaxin consists of 20 amino acid residues, SRVVKCSGFRPGSPDSREFC, with a disulfide-bridge between Cys-6 and Cys-20. The structure of its biosynthetic precursor was deduced from cloned skin cDNA and consists of 67 amino acid residues encoding a single copy of vasorelaxin (vasorelaxin, accession number: ). Synthetic vasorelaxin caused a profound relaxation of rat arterial smooth muscle with an EC50 of 6.76 nM. HE860494相似文献
24.
Wei Wang Mei Zhang Weimin Sun Shanmin Yang Ying Su Hengshan Zhang Chaomei Liu Xinfeng Li Ling Lin Sunghee Kim Paul Okunieff Zhenhuan Zhang Lurong Zhang 《PloS one》2013,8(10)
Most human pancreatic cancer cells are resistant to tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis. However, the mechanisms by which pancreatic cancer cells utilize their extracellular molecules to counteract the proapoptotic signaling mediated by the TNF family are largely unknown. In this study, we demonstrate for the first time that DcR3, a secreted decoy receptor that malignant pancreatic cancer cells express at a high level, acts as an extracellular antiapoptotic molecule by binding to TRAIL and counteracting its death-promoting function. The reduction of DcR3 with siRNA unmasked TRAIL and greatly enhanced TRAIL-induced apoptosis. Gemcitabine, a first-line drug for pancreatic cancer, also reduced the level of DcR3. The addition of DcR3 siRNA further enhanced gemcitabine-induced apoptosis. Notably, our in vivo study demonstrated that the therapeutic effect of gemcitabine could be enhanced via further reduction of DcR3, suggesting that downregulation of DcR3 in tumor cells could tip the balance of pancreatic cells towards apoptosis and potentially serve as a new strategy for pancreatic cancer therapy. 相似文献
25.
目的观察Tropic1808基因重组蛋白对坐骨神经损伤后再生的影响。方法SD大鼠16只,分为Tropic1808基因重组蛋白组和生理盐水组,切断左侧坐骨神经,硅胶管套接后两神经断端间距10mm,再生室内注入Tropic 1808基因重组蛋白液(500μg/ml)或生理盐水13μl。术后每4周做一次足迹试验,16周时作神经干动作电位、脊髓前角运动神经元数、腓肠肌纤维截面积、硅胶管中段再生神经等检测。结果Tropic1808基因重组蛋白组SFI的恢复、神经干动作电位、脊髓前角运动神经元数、腓肠肌纤维截面积、硅胶管中段再生神经有髓神经纤维数等结果均明显优于生理盐水组,有统计学意义。电镜观察表明Tropic1808组再生轴突较NS组粗,髓鞘较生理盐水组厚。结论Tropic1808基因重组蛋白有促进大鼠坐骨神经再生的作用。 相似文献
26.
Organelle positioning and movement in oocytes is largely mediated by microtubules (MTs) and their associated motor proteins. While yet to be studied in germ cells, cargo trafficking in somatic cells is also facilitated by specific recognition of acetylated MTs by motor proteins. We have previously shown that oocyte-restricted PADI6 is essential for formation of a novel oocyte-restricted fibrous structure, the cytoplasmic lattices (CPLs). Here, we show that α-tubulin appears to be associated with the PADI6/CPL complex. Next, we demonstrate that organelle positioning and redistribution is defective in PADI6-null oocytes and that alteration of MT polymerization or MT motor activity does not induce organelle redistribution in these oocytes. Finally, we report that levels of acetylated microtubules are dramatically suppressed in the cytoplasm of PADI6-null oocytes, suggesting that the observed organelle redistribution failure is due to defects in stable cytoplasmic MTs. These results demonstrate that the PADI6/CPL superstructure plays a key role in regulating MT-mediated organelle positioning and movement. 相似文献
27.
28.
A morin–zinc(II) complex (MZ) was synthesized and its interaction with bovine serum albumin (BSA) were studied by molecular spectroscopy including fluorescence emission spectra, UV-visible spectra, circular dichroism (CD) spectra, three-dimensional fluorescence spectra, and synchronous fluorescence spectra. The interaction mechanism of BSA and MZ was discussed by fluorescence quenching method and Förster non-radiation energy transfer theory. The thermodynamic parameters ΔH θ, ΔG θ, ΔS θ at different temperatures were calculated and the results indicate the interaction is an exothermic as well as entropy-driven process. Hydrogen bond forces played the most important role in the reaction. The fluorescence probe experiment showed that the binding site of MZ is in subdomain IIA of BSA and the distance between BSA and MZ is 3.17 nm at normal body temperature. The conformation changes of BSA in presence of MZ were investigated by CD spectra and three-dimensional fluorescence spectra. 相似文献
29.
Cell migration is mediated by ion channels and transporters, and plays crucial roles in a variety of physiological and pathological processes. Previously, our studies have shown that a Ca(2+)-regulated K(+) current exists in B-16 murine melanoma cells, and that endothelin-1 (ET-1) inhibits the K(+) current via a PKC-dependent pathway. In the present study, patch-clamp whole-cell recording and transwell migration assays were used to examine the effects of ET-1 on B-16 murine melanoma cell migration. ET-1 (100 nM in the injection pipette and 10 nM in the incubation medium) decreased the K(+) current amplitude by 33.0 +/- 2.5% and inhibited migration of B-16 cells by 57.4 +/- 9.4%. Similarly, the Ca(2+)-regulated K(+) channel blockers, BaCl(2) and quinidine, decreased the K(+) current by 20.5 +/- 1.0% and 36.6 +/- 1.2%, respectively, and slowed migration of B-16 melanoma cells by 37.1 +/- 8.6% and 42.7 +/- 8.8%, respectively. The effect of ET-1 on the K(+) current and cell migration was simulated by ET-3. In contrast, the K(+) channel opener, diclofenac, increased the K(+) current by 128.8 +/- 11.7%, 257.4 +/- 35.8% at concentrations of 1 and 5 mM, respectively. Likewise, the migration of B-16 murine melanoma cells dramatically increased by 75.6 +/- 12.7% in the presence of 100 microM diclofenac in incubation medium. Furthermore, the ET-1- and ET-3-induced inhibition of K(+) current and migration was abrogated by diclofenac. In the presence of diclofenac, ET-1 only reduced the K(+) current amplitude by 10.6 +/- 1.1%, and slowed B-16 cell migration by only 10.8 +/- 8.9%. The results suggest that the K(+) channel-dependent migration of B-16 melanoma cells is modulated by ET-1. Cell Motil. 相似文献
30.