全文获取类型
收费全文 | 106526篇 |
免费 | 10740篇 |
国内免费 | 6018篇 |
专业分类
耳鼻咽喉 | 1039篇 |
儿科学 | 1773篇 |
妇产科学 | 1095篇 |
基础医学 | 10540篇 |
口腔科学 | 1753篇 |
临床医学 | 13059篇 |
内科学 | 14496篇 |
皮肤病学 | 1539篇 |
神经病学 | 5104篇 |
特种医学 | 3745篇 |
外国民族医学 | 42篇 |
外科学 | 10918篇 |
综合类 | 20510篇 |
现状与发展 | 22篇 |
一般理论 | 29篇 |
预防医学 | 9297篇 |
眼科学 | 2890篇 |
药学 | 10866篇 |
131篇 | |
中国医学 | 6987篇 |
肿瘤学 | 7449篇 |
出版年
2024年 | 387篇 |
2023年 | 1534篇 |
2022年 | 3633篇 |
2021年 | 4866篇 |
2020年 | 3902篇 |
2019年 | 3175篇 |
2018年 | 3269篇 |
2017年 | 3476篇 |
2016年 | 3224篇 |
2015年 | 4644篇 |
2014年 | 5967篇 |
2013年 | 6223篇 |
2012年 | 8799篇 |
2011年 | 9375篇 |
2010年 | 6928篇 |
2009年 | 5741篇 |
2008年 | 6631篇 |
2007年 | 6570篇 |
2006年 | 6095篇 |
2005年 | 5417篇 |
2004年 | 3970篇 |
2003年 | 3655篇 |
2002年 | 3153篇 |
2001年 | 2449篇 |
2000年 | 1930篇 |
1999年 | 1476篇 |
1998年 | 789篇 |
1997年 | 749篇 |
1996年 | 538篇 |
1995年 | 496篇 |
1994年 | 398篇 |
1993年 | 289篇 |
1992年 | 405篇 |
1991年 | 382篇 |
1990年 | 363篇 |
1989年 | 337篇 |
1988年 | 264篇 |
1987年 | 250篇 |
1986年 | 235篇 |
1985年 | 185篇 |
1984年 | 123篇 |
1983年 | 93篇 |
1982年 | 61篇 |
1981年 | 64篇 |
1979年 | 91篇 |
1978年 | 62篇 |
1977年 | 62篇 |
1974年 | 68篇 |
1973年 | 63篇 |
1972年 | 67篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
Hui Chun Zhan Lorraine J Gudas Dean Bok Robert Rando David M Nanus Satish K Tickoo 《Clinical cancer research》2003,9(13):4897-4905
PURPOSE: Retinoids, a group of compounds, including vitamin A (retinol), and related metabolites, have been shown to regulate the growth and differentiation of many types of cells. IFN-alpha and either 13-cis-retinoic acid or liposomal all-trans retinoic acid have been used in the treatment of patients with metastatic renal cell carcinoma. We knew that samples from renal cell carcinomas contained greatly reduced levels of retinol and retinyl esters relative to samples from normal human kidney. This prompted us to examine the levels of LRAT (lecithin:retinol acyltransferase) protein in various subtypes of human kidney cancers relative to normal human kidney by immunohistochemistry. EXPERIMENTAL DESIGN: We examined 31 partial or radical nephrectomy specimens diagnosed with kidney tumors between 1997 and 1998. Representative paraffin-embedded tissue blocks from each tumor, with each containing adjacent nonneoplastic renal parenchyma, were used for immunohistochemical analysis with affinity purified antibodies to human LRAT protein. RESULTS: LRAT protein was detected at high levels in the epithelial cells in the tubules and the lining of Bowman's capsule in the glomeruli of normal, nonneoplastic kidney sections. Among the 31 tumors, there were 13 cases of conventional (clear cell) renal cell carcinoma (RCC; including 2 multilocular cystic RCCs), 7 papillary RCC, 6 chromophobe RCC, 1 RCC, unclassified, and 4 renal oncocytoma. All tumors showed diffuse immunoreactivity for LRAT. In each case, the staining was uniform throughout the tumor, with only minimal variation in the staining intensity between different areas. All 4 renal oncocytomas, 2 of 6 chromophobe RCCs, 1 conventional (clear cell) carcinoma, 1 RCC, unclassified, and 2 conventional RCCs, which were of the multilocular cystic-type stained strongly (3+) for LRAT. In contrast, the remaining conventional RCCs and the papillary RCC samples stained much less intensely for LRAT. Of the 10 tumors that stained 3+ for LRAT in the study, 9 were either benign tumors or tumors with low malignant potential. CONCLUSIONS: These data show that LRAT expression is higher in renal tumors with an indolent biological behavior. Additional studies will ascertain if LRAT possesses any prognostic or therapeutic role in renal cancer. 相似文献
994.
Beatrice M Seddon Geoffrey S Payne Laura Simmons Ruth Ruddle Rachel Grimshaw Siew Tan Alison Turner Florence Raynaud Gavin Halbert Martin O Leach Ian Judson Paul Workman 《Clinical cancer research》2003,9(14):5101-5112
PURPOSE: To perform a Phase I study of SR-4554, a fluorinated 2-nitroimidazole noninvasive probe of tumor hypoxia detected by (19)F magnetic resonance spectroscopy (MRS). EXPERIMENTAL DESIGN: SR-4554 administration, on days 1 and 8, was followed by plasma sampling for pharmacokinetic studies and by three MRS studies performed over 24 h on days 8 and 9. Unlocalized MR spectra were acquired from tumor (10- or 16-cm dual resonant 1H/19F surface coil; 1.5 T Siemens Vision MR system; 2048 transients acquired over 34 min; 1.28-ms adiabatic pulse; repetition time, 1 s). Plasma drug concentrations were measured with a validated high-performance liquid chromatography method. Noncompartmental pharmacokinetic analysis was performed. RESULTS: Eight patients underwent pharmacokinetic studies, receiving doses of SR-4554 of 400-1600 mg/m(2). Peak plasma concentrations increased linearly with the SR-4554 dose (r(2) = 0.80; P = 0.0002). The plasma elimination half-life was relatively short (mean +/- SD, 3.28 +/- 0.59 h), and plasma clearance was quite rapid (mean +/- SD, 12.8 +/- 3.3 liters/h). Urinary recovery was generally high. SR-4554 was well tolerated. A single patient experienced dose-limiting toxicity (nausea and vomiting) at 1600 mg/m(2). The maximum tolerated dose was 1400 mg/m(2). SR-4554 was detected spectroscopically in tumors immediately after infusion at doses of 400-1600 mg/m(2). At the highest dose (1600 mg/m(2)), SR-4554 was detectable in tumor at 8 h, but not at 27 h. CONCLUSIONS: SR-4554 has plasma pharmacokinetic and toxicity profiles suitable for use as a hypoxia probe. It can be detected in tumors by unlocalized MRS. Additional clinical studies are warranted. 相似文献
995.
996.
复方苦参洗剂中小檗碱的含量测定 总被引:2,自引:0,他引:2
目的: 建立三元络合物比色法测定复方苦参洗剂中小檗碱的含量,为制剂质量控制提供依据.方法: 小檗碱在pH6.7的溶液中, 与溴酚蓝、奎宁形成三元络合物比色, 经氯仿提取, 在610 nm波长处测定吸收度.结果: 回归方程为A=0.182C-0.004(r=0.999 9),小檗碱在0.8~4 mg·L-1浓度范围内线性关系良好(r=0.999 9),平均回收率为98.65%,RSD为1.12%.结论: 本方法准确,灵敏度好,可用于复方苦参洗剂中小檗碱的含量测定. 相似文献
997.
目的 :探讨基因工程药物NIF、NHH、TNHH对大鼠动脉阻塞性脑损伤的治疗作用。方法 :用线栓法将24只大鼠制成动脉阻塞性脑缺血损伤模型后分为治疗组 (3组 )和模型对照组 ,每组6只。治疗组静脉给予NIF、NHH、TNHH ,模型组给予生理盐水。分别于术后4、8、24、48、72h进行神经行为学评分 ;术后72h取血测定血清APTT ,判断凝血功能 ;取脑组织行TTC染色 ,计算梗塞灶体积 ;HE染色观察脑组织病理变化。结果 :治疗组各时间点行为学评分均优于模型组 (P<0 05) ,血清APTT比模型组均有明显延长 (P<0 05) ,脑组织梗塞灶体积比模型组小 (P<0 05) ,HE染色脑组织病理变化均较模型组轻。结论 :NIF、NHH、TNHH对大鼠动脉阻塞性脑缺血损伤有明显的保护作用 ,其中以TNHH最优。 相似文献
998.
目的探讨经肝动脉化疗栓塞(TACE)后肝癌细胞中增殖细胞核抗原(PCNA)广凋亡细胞比值与肝细胞肝癌分化程度的关系。方法应用原位末端标记法(TUNEL)及免疫组化双染色技术,对60例肝细胞肝癌石蜡包埋组织进行检测。结果不同分化程度癌组织中细胞凋亡和PCNA的阳性率不同。分化程度高,细胞凋亡阳性率高、PCNA阳性率偏低;分化程度低,细胞凋亡阳性率偏低、PCNA阳性率高。随分化程度的降低,PCNA广凋亡细胞的比值显著增加,两者有相关性。结论PCNA/凋亡细胞的比值可作为评估肝细胞肝癌分化程度的指标。 相似文献
999.
液相色谱-电喷雾质谱联用法测定人血浆中托吡酯 总被引:2,自引:0,他引:2
目的:建立测定人血浆中托吡酯的液相色谱-电喷雾质谱联用(LC/ESI-MS)法。方法:待测血浆0.2 mL经甲醇沉淀除去蛋白,离心,取上清液10μL在Diamonsil C18柱上分离,流动相为甲醇-2.5 mmol·L-1醋酸铵(80:20),流速0.4 mL·min-1,LC/ESI-MS选择离子检测,负离子模式,用于定量分析的离子分别为m/z338(托吡酯)和m/z 356(吲哚美辛,内标)。结果:血浆中无干扰测定的内源性物质,每个样品分析时间小于7 min;本法线性范围为40-2560 ng·mL-1,最低定量浓度为40 ng·mL-1;日内、日间RSD分别小于3.8%和13.4%,相对偏差小于5.9%。结论:该法操作简便、快速、准确、灵敏度高,适用于临床药物动力学研究。 相似文献
1000.