全文获取类型
收费全文 | 137703篇 |
免费 | 11630篇 |
国内免费 | 8243篇 |
专业分类
耳鼻咽喉 | 1195篇 |
儿科学 | 1952篇 |
妇产科学 | 1284篇 |
基础医学 | 14425篇 |
口腔科学 | 2338篇 |
临床医学 | 18066篇 |
内科学 | 18396篇 |
皮肤病学 | 1855篇 |
神经病学 | 6239篇 |
特种医学 | 5138篇 |
外国民族医学 | 46篇 |
外科学 | 12073篇 |
综合类 | 26556篇 |
现状与发展 | 28篇 |
一般理论 | 8篇 |
预防医学 | 11689篇 |
眼科学 | 3510篇 |
药学 | 14974篇 |
109篇 | |
中国医学 | 8061篇 |
肿瘤学 | 9634篇 |
出版年
2024年 | 328篇 |
2023年 | 1485篇 |
2022年 | 3909篇 |
2021年 | 5143篇 |
2020年 | 4009篇 |
2019年 | 3436篇 |
2018年 | 3506篇 |
2017年 | 3723篇 |
2016年 | 3635篇 |
2015年 | 5737篇 |
2014年 | 7303篇 |
2013年 | 7514篇 |
2012年 | 11054篇 |
2011年 | 11802篇 |
2010年 | 8799篇 |
2009年 | 7538篇 |
2008年 | 8919篇 |
2007年 | 8856篇 |
2006年 | 8380篇 |
2005年 | 7823篇 |
2004年 | 5745篇 |
2003年 | 5766篇 |
2002年 | 4639篇 |
2001年 | 3764篇 |
2000年 | 3047篇 |
1999年 | 2339篇 |
1998年 | 1402篇 |
1997年 | 1418篇 |
1996年 | 1000篇 |
1995年 | 893篇 |
1994年 | 746篇 |
1993年 | 515篇 |
1992年 | 572篇 |
1991年 | 493篇 |
1990年 | 436篇 |
1989年 | 345篇 |
1988年 | 317篇 |
1987年 | 264篇 |
1986年 | 218篇 |
1985年 | 184篇 |
1984年 | 99篇 |
1983年 | 77篇 |
1982年 | 49篇 |
1981年 | 49篇 |
1980年 | 29篇 |
1979年 | 45篇 |
1978年 | 34篇 |
1976年 | 23篇 |
1973年 | 27篇 |
1970年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Lim YH Leem MJ Shin DH Chang HB Hong SW Moon EY Lee DK Yoon SJ Woo WS 《Archives of pharmacal research》1999,22(2):208-212
Activity-guided fractionation of the roots of Anthriscus sylvestris resulted in the isolation and characterization of five cytotoxic compounds, deoxypodophyllotoxin (1), falcarindiol (2), and angeloyl podophyllotoxin (5) from the hexane soluble fraction and morelensin (3), bursehernin (4) from the chloroform soluble fraction. It is the first report of the occurrence of compound 5 in nature. 相似文献
992.
Optimum conditions of chiral derivatization reaction of beta-blockers acebutolol, arotinolol, beta-xolol, bisoprolol, celiprolol, metoprolol and pindolol) with (-)-menthyl chloroformate were investigated for the resolution by HPLC. With more than 30 times molar excess of (-)-menthyl chloroformate chiral derivatization reactions were completed within one hour at room temperature except arotinolol and celiprolol. Diastereomeric derivatives of beta-blockers were well resolved on the ODS column using acetonitrile-methanol-water as a mobile phase. 相似文献
993.
In Hwa Chung Choong Sup Kim Jae Hong Seo Bong Young Chung 《Archives of pharmacal research》1999,22(4):391-397
The quaternary ammonium cephalosporin derivatives were prepared with various pyridines substituted at the 3 or/and 4 position. Their in vitro antibacterial activities were determined and substituent effect on pyridine nucleus was studied. Preparation of substituted pyridines are also described. 相似文献
994.
Hak Cheol Kwon Byeong Gon Lee Seung Hee Kim Chil Mann Jung Sung Youl Hong Jeung Whan Han Hyang Woo Lee Ok Pyo Zee Kang Ro Lee 《Archives of pharmacal research》1999,22(4):410-413
In bioassay-guided search for inducible nitric oxide synthase (iNOS) inhibitory compounds from higher plants of South Korea, two beta-carboline alkaloids, 4-methoxy-1-vinyl-beta-carboline (1) and 4,8-dimethoxy-l-vinyl-beta-carboline (2) have been isolated from the cortex of Melia azedarach var. japonica. The structures of these compounds were elucidated on the basis of spectroscopic data. Compounds 1 and 2 showed marked inhibitory activity of iNOS on LPS- and interferon-gamma-stimulated RAW 264.7 cells. 相似文献
995.
Cytotoxicity of urushiols isolated from sap of Korean lacquer tree (Rhus vernicifera stokes) 总被引:1,自引:0,他引:1
Hong DH Han SB Lee CW Park SH Jeon YJ Kim MJ Kwak SS Kim HM 《Archives of pharmacal research》1999,22(6):638-641
Cytotoxicities of four urushiols, congeners isolated from the sap of Korean lacquer tree (Rhus vernicifera Stokes), to 29 human cancer cell lines originated from 9 organs were evaluated. Their values of 50% growth inhibition were below 4 microg/ml, and showed cell line specific cytotoxicity. The present result is the first report on the cytotoxicity of urushiols suggesting that they would have an anticancer activity to human cancer cells. 相似文献
996.
氟伐他汀对自发性高血压大鼠阻力血管 功能的影响 总被引:7,自引:0,他引:7
AIM: To evaluate the effects of fluvastatin, a hydroxymethylglutaryl-CoA (HMG-CoA) reductase inhibitor, on the alterations of structure and function of resistant vessels in spontaneously hypertensive rats (SHR). METHODS: Eight-week-old male SHR were given fluvastatin 20 mg.kg-1.d-1 by gavage. Rats were decapitated at 16 wk. Wall-to-lumen area ratios (W/L) of thoracic aorta and mesenteric arteries (3rd grade branch) were assessed by morphometric assay. The effects of fluvastatin on vascular reactivity to sodium nitroprusside (SNP) and norepinephrine (NE), were studied with rings of thoracic aorta and mesenteric arteries isolated from rats. RESULTS: After 8 wk of treatment, histological examination showed that the wall-to-lumen area ratio was lower in SHRflu than that in SHR (0.44 +/- 0.09 vs 0.79 +/- 0.09, P < 0.05). EC50 of vasodilation response was much lower in SHRflu than that in SHR [(4.9 vs 190) pmol.L-1, P < 0.05], while EC50 of mesenteric artery rings from SHRflu was somewhat lower than that of SHR [(0.02 vs 0.04) nmol.L-1, P > 0.05]. In both aortic and mesenteric artery rings, EC50 of vasoconstriction in response to NE from SHRflu was higher than that of SHR [thoracic aorta: (0.20 vs 0.02) nmol.L-1, P < 0.05; mesentric arteries: (1.46 vs 0.72) nmol.L-1, P < 0.05]. CONCLUSION: Short-term treatment with fluvastatin ameliorated the vasomotoricity of resistant vessels, enhanced the sensitivity to vasodilator and depressed the sensitivity to vasoconstrictor; fluvastatin also attenuated the resistant vascular hypertrophy during the development of hypertension in SHR. 相似文献
997.
998.
999.
Despite advances and improvements in diagnosis and treatment of upper aerodigestive tumors including head and neck and lung cancers, the overall survival rate of these patients remains poor. Prevention, early diagnosis, and novel therapy are under active investigation to improve the outcome of the diseases. In particular, chemopreventive strategy is a novel approach to reduce the invasive tumors by reversing the premalignant lesions with certain differentiating agents (i.e., retinoids). To conduct effective chemopreventive trials, there has been a great surge of interest in defining the biomarkers associated with the specific stages of the carcinogenesis and with intermediate end points during the therapy. Carcinogenesis in the upper aerodigestive tract has been explained by two theories, field cancerization and multistep process. The driving forces behind these processes are noted by accumulated genetic abnormalities in the entire epithelium of the airway. These genetic abnormalities include chromosome abnormalities, specific gene alterations (i.e., ras gene family, tumor suppressor genes, growth factors and their receptors), and proliferation and differentiation markers. These biomarkers are herein described in this review article. 相似文献
1000.
提出了使用Excel 7.0 for Windows95简便和快速优化换热网络的方法。首先由Monte Carlo法确定全局最优点的近似位置,然后由“Solver”求得精确解。全部优化过程由VBA语言编写。此法可用于解决许多工程优化问题。 相似文献