全文获取类型
收费全文 | 1770309篇 |
免费 | 128887篇 |
国内免费 | 2546篇 |
专业分类
耳鼻咽喉 | 22831篇 |
儿科学 | 59124篇 |
妇产科学 | 49059篇 |
基础医学 | 243074篇 |
口腔科学 | 48862篇 |
临床医学 | 152441篇 |
内科学 | 343786篇 |
皮肤病学 | 34738篇 |
神经病学 | 145545篇 |
特种医学 | 73100篇 |
外国民族医学 | 476篇 |
外科学 | 270970篇 |
综合类 | 41978篇 |
现状与发展 | 3篇 |
一般理论 | 544篇 |
预防医学 | 139626篇 |
眼科学 | 39159篇 |
药学 | 130147篇 |
37篇 | |
中国医学 | 3597篇 |
肿瘤学 | 102645篇 |
出版年
2018年 | 35246篇 |
2017年 | 27806篇 |
2016年 | 31036篇 |
2015年 | 15867篇 |
2014年 | 21364篇 |
2013年 | 32017篇 |
2012年 | 48971篇 |
2011年 | 64312篇 |
2010年 | 43821篇 |
2009年 | 36054篇 |
2008年 | 61141篇 |
2007年 | 65397篇 |
2006年 | 46490篇 |
2005年 | 46644篇 |
2004年 | 47214篇 |
2003年 | 46206篇 |
2002年 | 43580篇 |
2001年 | 75939篇 |
2000年 | 78743篇 |
1999年 | 66572篇 |
1998年 | 17928篇 |
1997年 | 16522篇 |
1996年 | 16384篇 |
1995年 | 16106篇 |
1994年 | 15162篇 |
1993年 | 14273篇 |
1992年 | 55470篇 |
1991年 | 53870篇 |
1990年 | 52690篇 |
1989年 | 50900篇 |
1988年 | 47276篇 |
1987年 | 46606篇 |
1986年 | 44319篇 |
1985年 | 42874篇 |
1984年 | 32061篇 |
1983年 | 27590篇 |
1982年 | 16172篇 |
1981年 | 14437篇 |
1979年 | 30475篇 |
1978年 | 21077篇 |
1977年 | 17769篇 |
1976年 | 16707篇 |
1975年 | 17580篇 |
1974年 | 21508篇 |
1973年 | 20675篇 |
1972年 | 18855篇 |
1971年 | 17771篇 |
1970年 | 16308篇 |
1969年 | 15287篇 |
1968年 | 13964篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Shuai Huang Run Wu Feng Gao Chunying Li Xianli Zhou 《Journal of natural medicines》2018,72(3):768-773
Two new flavonol glycosides, bootanenside I and II (1 and 2), along with ten known compounds (3–12), were isolated from whole plant of Liparis bootanensis Griff. Their structures were elucidated on the basis of extensive spectroscopic analyses, including high-resolution electrospray-ionization mass spectrometry (HR–ESIMS) and one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR). The cytotoxicity of the compounds was investigated against HCT116 human cancer cell line, revealing that none of them possessed considerable cytotoxic activity. Bioassays of the new metabolites showed that compounds 1 and 2 displayed moderate in vitro antiinflammatory activity by inhibiting expression of inducible nitric oxide synthase (iNOS) protein in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophage cells. 相似文献
102.
Gorawit Yusakul Tharita Kitisripanya Thaweesak Juengwatanatrakul Seiichi Sakamoto Hiroyuki Tanaka Waraporn Putalun 《Journal of natural medicines》2018,72(3):641-650
Miroestrol and deoxymiroestrol are the most potent phytoestrogens of Pueraria candollei var. mirifica, having been proved as an effective herb for menopausal symptoms in folk medicines and clinical trials. To ensure efficacy and safety of P. candollei var. mirifica involved in nutraceutical products being available worldwide, the content of potent phytoestrogens as active ingredients should be specified. Therefore, in this study, we produced a monoclonal antibody for total analysis of potent estrogenic miroestrol and deoxymiroestrol, for which an analytical method was developed using a procedure for an indirect competitive enzyme-linked immunosorbent assay. The antibody exhibited equal reactivity against miroestrol and deoxymiroestrol. The sensitivity of determination was in the range of 31.3–500 ng/ml with high precision. The analytical parameters, such as accuracy (99.6–106% recovery) and high correlation with a HPLC–UV method, indicated the reliability of analysis. This method is of high performance, and it is cheap to control optimal miroestrol and deoxymiroestrol doses of P. candollei var. mirifica nutraceutical products. 相似文献
103.
Lignans are widely distributed in plants and exhibit significant pharmacological effects, including anti-tumor and antioxidative activities. Here, we describe the total synthesis of schizandriside (1), a compound we previously isolated from Saraca asoca by monitoring antioxidative activity using the 1,1-diphenyl-2-picrylhydrazyl radical scavenging assay. Starting from a tandem Michael-aldol reaction, the lignan skeleton was synthesized in 6 steps, including a cyclization step. To determine the stereochemistry of 1, we synthesized the natural product (±)-isolariciresinol (18) from alcohol 17. Comparison of the spectral data showed good agreement. Glycosylation was investigated using four different glycosyl donors. Only the Koenigs–Knorr condition using silver trifluoromethanesulfonate with 1,1,3,3-tetramethylurea provided the glycosylated product. Deprotection and purification using reverse-phase high-performance liquid chromatography gave schizandriside (1) and its diastereomer saracoside (2). Synthesized 1, 2 and 18 showed antioxidant activity with IC50?=?34.4, 28.8, 53.0 μM, respectively. 相似文献
104.
Anmar M. Nassir Naiyer Shahzad Ibrahim A.A. Ibrahim Iqbal Ahmad Shadab Md Mohammad R. Ain 《Saudi Pharmaceutical Journal》2018,26(6):876-885
Resveratrol (RL), a natural polyphenol, is known for its diverse biological effects against various human cancer cell lines. But low aqueous solubility, poor bioavailability, and stability limit its efficacy against prostate cancer. In this study polymeric nanoparticles encapsulating resveratrol (RLPLGA) were designed and their cytotoxic and mode of apoptotic cells death against prostate cancer cell line (LNCaP) was determined. Nanoparticles were prepared by solvent displacement method and characterized for particle size, TEM, entrapment efficiency, DSC and drug release study. RLPLGA exhibited a significant decrease in cell viability with 50% and 90% inhibitory concentration (IC50 and IC90) of 15.6?±?1.49 and 41.1?±?2.19?μM respectively against the LNCaP cells. This effect was mediated by apoptosis as confirmed by cell cycle arrest at G1-S transition phase, externalization of phosphatidylserine, DNA nicking, loss of mitochondrial membrane potential and reactive oxygen species generation in LNCaP cells. Furthermore, significantly greater cytotoxicity to LNCaP cells was observed with nanoparticles as compared to that of free RL at all tested concentrations. RLPLGA nanoparticles presented no adverse cytotoxic effects on murine macrophages even at 200?μM. Our findings support the potential use of developed resveratrol loaded nanoparticle for the prostate cancer chemoprevention/ chemotherapy with no adverse effect on normal cells. 相似文献
105.
Huilong Wen Zhong Wu Huidong Hu Yixiong Wu Gang Yang Jiajun Lu Guang Yang Gang Guo Qirong Dong 《Journal of natural medicines》2018,72(1):57-63
Pachymic acid (PA) is a lanostane type triterpenoid isolated from Poria cocos, which possesses an anti-tumor effect in breast cancer, prostate cancer, lung cancer, and bladder cancer cells. In this study, we investigated the effect of PA on the growth and apoptosis of human immortalized cell line (HOS) and primary osteosarcoma cells by a Cell Counting Kit-8 (CCK-8) and Annexin V and propidium iodide (PI) staining, respectively. Western blot was used to measure the expression of cleaved Caspase 3, PTEN, and AKT, as well as the AKT phosphorylation. The Caspase 3 activity was determined using the Caspase-3 Colorimetric Assay Kit. From the results, PA significantly reduced cell proliferation in a concentration- and time-dependent manner. PA also induced cell apoptosis in a dose-dependent fashion. PA treatment led to increased Caspase 3 activation and PTEN expression, as well as reduced AKT phosphorylation. Moreover, Ac-DEVD-CHO (a Caspase 3/7 inhibitor) pre-treatment or PTEN knockdown partially blocked the effects of PA on cell proliferation and apoptosis. Caspase 3/7 inhibitor had an additive effect with PTEN knockdown. Collectively, our results suggested that induction of apoptosis by PA was mediated in part by PTEN/AKT signaling and Caspase 3/7 activity. This study provides evidence that PA might be useful in the treatment of human osteosarcoma. 相似文献
106.
Yang Zhang Bowen Deng Yida Cui Xue Chen Jiayi Bi Guogang Zhang 《Journal of natural medicines》2018,72(4):946-953
Two new secoiridoid glucosides, ilexpublignoside (1), pubzenoside (2), and a new lignan, ilexlignan B (3), along with seven known compounds (4–10) were isolated from the roots of Ilex pubescens for the first time. Their chemical structures were elucidated on the basis of extensive spectroscopic methods, including IR, UV, HR-ESI–MS, CD, NMR experiments, as well as comparison with the reported data. 相似文献
107.
108.
Sigmund Hough 《Sexuality and disability》2018,36(1):101-102
109.
Juan R. Ordoñana Juan F. Sánchez Romera Lucía Colodro-Conde Eduvigis Carrillo Francisca González-Javier Juan J. Madrid-Valero José J. Morosoli-García Francisco Pérez-Riquelme José M. Martínez-Selva 《Gaceta sanitaria / S.E.S.P.A.S》2018,32(1):92-95
Genetically informative designs and, in particular, twin studies, are the most widely used methodology to analyse the relative contribution of genetic and environmental factors to inter-individual variability. These studies basically compare the degree of phenotypical similarity between monozygotic and dizygotic twin pairs. In addition to the traditional estimate of heritability, this kind of registry enables a wide variety of analyses which are unique due to the characteristics of the sample. The Murcia Twin Registry is population-based and focused on the analysis of health-related behaviour. The observed prevalence of health problems is comparable to that of other regional and national reference samples, which guarantees its representativeness. Overall, the characteristics of the Registry facilitate developing various types of research as well as genetically informative designs, and collaboration with different initiatives and consortia. 相似文献
110.