全文获取类型
收费全文 | 7986篇 |
免费 | 648篇 |
国内免费 | 39篇 |
出版年
2024年 | 8篇 |
2023年 | 32篇 |
2022年 | 66篇 |
2021年 | 173篇 |
2020年 | 119篇 |
2019年 | 186篇 |
2018年 | 211篇 |
2017年 | 186篇 |
2016年 | 324篇 |
2015年 | 496篇 |
2014年 | 510篇 |
2013年 | 570篇 |
2012年 | 743篇 |
2011年 | 712篇 |
2010年 | 511篇 |
2009年 | 386篇 |
2008年 | 480篇 |
2007年 | 480篇 |
2006年 | 385篇 |
2005年 | 368篇 |
2004年 | 350篇 |
2003年 | 302篇 |
2002年 | 311篇 |
2001年 | 86篇 |
2000年 | 95篇 |
1999年 | 98篇 |
1998年 | 55篇 |
1997年 | 45篇 |
1996年 | 39篇 |
1995年 | 34篇 |
1994年 | 24篇 |
1993年 | 21篇 |
1992年 | 30篇 |
1991年 | 31篇 |
1990年 | 17篇 |
1989年 | 25篇 |
1988年 | 19篇 |
1987年 | 17篇 |
1986年 | 13篇 |
1985年 | 12篇 |
1984年 | 13篇 |
1983年 | 6篇 |
1981年 | 4篇 |
1979年 | 9篇 |
1978年 | 7篇 |
1977年 | 9篇 |
1976年 | 5篇 |
1975年 | 14篇 |
1974年 | 7篇 |
1968年 | 4篇 |
排序方式: 共有8673条查询结果,搜索用时 25 毫秒
101.
102.
β‐arrestin 1 and 2 (also known as arrestin 2 and 3) are homologous adaptor proteins that regulate seven‐transmembrane receptor trafficking and signalling. Other proteins with predicted ‘arrestin‐like’ structural domains but lacking sequence homology have been indicated to function like β‐arrestin in receptor regulation. We demonstrate that β‐arrestin2 is the primary adaptor that rapidly binds agonist‐activated β2 adrenergic receptors (β2ARs) and promotes clathrin‐dependent internalization, E3 ligase Nedd4 recruitment and ubiquitin‐dependent lysosomal degradation of the receptor. The arrestin‐domain‐containing (ARRDC) proteins 2, 3 and 4 are secondary adaptors recruited to internalized β2AR–Nedd4 complexes on endosomes and do not affect the adaptor roles of β‐arrestin2. Rather, the role of ARRDC proteins is to traffic Nedd4–β2AR complexes to a subpopulation of early endosomes. 相似文献
103.
104.
Seung Hyun Kim Sin-Duk Jang Ki Yong Lee Sang Hyun Sung 《Journal of enzyme inhibition and medicinal chemistry》2013,28(1):230-233
A methanolic extract of dried leaves of Polygala japonica Houtt (Polygalaceae) significantly attenuated nitric oxide production in lipopolysaccharide-simulated BV2 microglia. Five anthraquinones chrysophanol (1), emodin (2), aloe-emodin (3), emodin 8-O-β-D-glucopyranoside (4) and trihydroxy anthraquinone (5), and four flavonoids kaempferol (6), chrysoeriol (7), kaempferol 3-gentiobioside (8) and isorhamnetin (9) were isolated from the methanolic extract using bioactivity-guided fractionation. Among them, compounds 1–4, 6 and 7 showed significant inhibitory effect on lipopolysaccharide-induced nitric oxide production in BV2 microglia at the concentrations ranging from 1.0 to 100.0 μM. 相似文献
105.
Muhammad Naeem Khan Muhammad Rasul Jan Jasmin Shah Sang Hak Lee Young Ho Kim 《Luminescence》2013,28(6):915-921
A highly sensitive and simple method for identifying sulpiride in pharmaceutical formulations and biological fluids is presented. The method is based on increased chemiluminescence (CL) intensity of a luminol–H2O2 system in response to the addition of Cr (III) under alkaline conditions. The CL intensity of the luminol–H2O2–Cr (III) system was greatly enhanced by the addition of sulpiride and the CL intensity was proportional to the concentration of sulpiride in a sample solution. Various parameters affecting the CL intensity were systematically investigated and optimized for determination of the sulpiride in a sample. Under the optimum conditions, the CL intensity was proportional to the concentration of sulpiride in the range of 0.068–4.0 µg/mL, with a good correlation coefficient of 0.997. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 8.50 × 10‐6 µg/mL and 2.83 × 10‐5 µg/mL, respectively. The method presented here produced good reproducibility with a relative standard deviation (RSD) of 2.70% (n = 7). The effects of common excipients and metal ions were studied for their interference effect. The method was validated statistically through recovery studies and successfully applied for the determination of sulpiride in pure form, pharmaceutical preparations and spiked human plasma samples. The percentage recoveries were found to range from 99.10 to 100.05% for pure form, 98.12 to 100.18% for pharmaceutical preparations and 97.9 to 101.4% for spiked human plasma. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
106.
Sang Taek Jung 《Biotechnology and Bioprocess Engineering》2013,18(4):625-636
Antibody Fc region, a recruiter and a frontline commander in the combat against cancer and infectious pathogens, mediates potent immune effector functions by engaging Fc receptors and serum complement proteins. Recent studies indicate that the Fc region is particularly amenable to modifications that enhance potency and serum stability through amino acid substitution and glycan modification. In order to modulate the interaction of the Fc domain with Fc-binding ligands (FcγRs, C1q, and FcRn), various engineering strategies have been employed; these studies are discussed in this review. 相似文献
107.
Dong Chil Koo So Yoon Baek Sang Hoon Jung Sang Hee Shim 《Biotechnology and Bioprocess Engineering》2013,18(5):926-931
Amethanolic extract of Dipsacus asper, having anti-diabetic activity, was examined as a possible aldose reductase (ALR2) inhibitor, a key enzyme involved in diabetic complications. Bioactivity guided fractionation led to the isolation of ten compounds, ursolic acid (1), oleanolic acid-3-O-α-L-arabinopyranoside (2), daucosterol (3), hederagenin-3-O-α-L-arabinopyranoside (4), sweroside(5), caffeic acid (6), esculetin (7), protocatechualdehyde (8), loganin (9), and vanilic acid (10) from the ethyl acetate fraction of D. asper methanol extract. Among them, compounds 4, 6, 7, and 8 exhibited inhibitory effects on aldose reductase, with IC50 values of 23.70, 16.71, 34.36, and 21.81 μM, respectively. This is the first report on the isolation of these compounds from D. asper, and the ALR2 inhibitory activity of hederagenin-3-O-α-L-arabinopyranoside. These results suggest the successful use of the extract of D. asper for ameliorating diabetic complications. 相似文献
108.
109.
Yoon Sang Kim Junho Ko Dong-Kwang Shin Chul-Hwan Kim Chul-Won Park 《Cluster computing》2013,16(2):209-217
There have been recent research activities on GPS-based FNET to prevent wide-area blackouts by monitoring frequency deviation. This paper introduces a system for monitoring regional frequencies in power grid developed as an advanced research project for intelligent wide-area protective relaying in South Korea. The system is implemented by modeling an actual 345 kV transmission system of South Korea using EMTP-RV and by measuring voltages and currents at five regions. The frequencies are estimated using our previous proposed method, a frequency estimation algorithm with gain compensation. The monitoring system implemented is used to examine frequency propagation effects and various fault conditions. Simulation results showed that the proposed system could achieve good performance regarding the frequency monitoring under both steady states and dynamic fault conditions. 相似文献
110.
Chung-Hwa Park Si Hyun Bae Hee Yeon Kim Ja Kyung Kim Eun Sun Jung Ho Jong Chun Myeong Jun Song Sung-Eun Lee Seok Goo Cho Jong Wook Lee Jong Young Choi Seung Kew Yoon Nam Ik Han Young Sok Lee 《Cytotherapy》2013,15(12):1571-1579
Background aimsMany rodent experiments and human studies on stem cell therapy have shown promising therapeutic approaches to liver diseases. We investigated the clinical outcomes of five patients with liver failure of various causes who received autologous CD34-depleted bone marrow-derived mononuclear cell (BM-MNC) transplantation, including mesenchymal stromal cells, through the hepatic artery.MethodsCD34-depleted BM-MNCs were obtained from five patients waiting for liver transplantation by bone marrow aspiration and using the CliniMACS CD34 Reagent System (Miltenyi Biotech, Bergisch Gladbach, Germany), and autologous hepatic artery infusion was performed. The causes of hepatic decompensation were hepatitis B virus (HBV), hepatitis C virus (HCV), propylthiouracil-induced toxic hepatitis and Wilson disease.ResultsSerum albumin levels improved 1 week after transplantation from 2.8 g/dL, 2.4 g/dL, 2.7 g/dL and 1.9 g/dL to 3.3 g/dL, 3.1 g/dL, 2.8 g/dL and 2.6 g/dL. Transient liver elastography data showed some change from 65 kPa, 33 kPa, 34.8 kPa and undetectable to 46.4 kPa, 19.8 kPa, 29.1 kPa and 67.8 kPa at 4 weeks after transplantation in a patient with Wilson disease, a patient with HCV, and two patients with HBV. Ascites decreased in two patients. One of the patients with HBV underwent liver transplantation 4 months after the infusion, and the hepatic progenitor markers (cytokeratin [CD]-7, CD-8, CD-9, CD-18, CD-19, c-Kit and epithelial cell adhesion molecule [EpCAM]) were highly expressed in the explanted liver.ConclusionsSerum albumin levels, liver stiffness, liver volume, subjective healthiness and quality of life improved in the study patients. Although these findings were observed in a small population, the results may suggest a promising future for autologous CD34-depleted BM-MNC transplantation as a bridge to liver transplantation in patients with liver failure. 相似文献