全文获取类型
收费全文 | 3796篇 |
免费 | 248篇 |
国内免费 | 118篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 35篇 |
妇产科学 | 9篇 |
基础医学 | 417篇 |
口腔科学 | 38篇 |
临床医学 | 151篇 |
内科学 | 344篇 |
皮肤病学 | 355篇 |
神经病学 | 78篇 |
特种医学 | 54篇 |
外科学 | 212篇 |
综合类 | 346篇 |
现状与发展 | 1篇 |
预防医学 | 168篇 |
眼科学 | 37篇 |
药学 | 1373篇 |
中国医学 | 423篇 |
肿瘤学 | 120篇 |
出版年
2024年 | 5篇 |
2023年 | 25篇 |
2022年 | 60篇 |
2021年 | 96篇 |
2020年 | 93篇 |
2019年 | 99篇 |
2018年 | 98篇 |
2017年 | 80篇 |
2016年 | 89篇 |
2015年 | 113篇 |
2014年 | 195篇 |
2013年 | 213篇 |
2012年 | 252篇 |
2011年 | 261篇 |
2010年 | 252篇 |
2009年 | 196篇 |
2008年 | 234篇 |
2007年 | 229篇 |
2006年 | 197篇 |
2005年 | 179篇 |
2004年 | 166篇 |
2003年 | 148篇 |
2002年 | 119篇 |
2001年 | 119篇 |
2000年 | 85篇 |
1999年 | 75篇 |
1998年 | 56篇 |
1997年 | 46篇 |
1996年 | 57篇 |
1995年 | 51篇 |
1994年 | 49篇 |
1993年 | 25篇 |
1992年 | 36篇 |
1991年 | 18篇 |
1990年 | 18篇 |
1989年 | 13篇 |
1988年 | 20篇 |
1987年 | 15篇 |
1986年 | 10篇 |
1985年 | 16篇 |
1984年 | 14篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 8篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1971年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有4162条查询结果,搜索用时 11 毫秒
11.
Background: Hybrid, combined or mixed bariatric surgery is the combination of a degree of ‘malabsorption’ (as achieved by the intestinal bypass) with a ‘rrestriction’
(as achieved by gastric bypass or gastroplasty), thereby simultaneously reducing the absorption of fats in the small bowel
and decreasing the intake of food. Methods: A modification of the bilio-pancreatic diversion (BPD) with a duodenal switch
procedure, vertical lineal gastrectomy and preservation of the pylorus, has been used in 23 patients. The antropyloric pump
and 4 cm of the duodenum are left intact to preserve physiologic gastric emptying and to prevent anastomotic ulcer. The use
of staplers and continuous running sutures reduces surgical risks and operative time. Results: One patient, converted from
a vertical gastroplasty, had an intrathoracic esophageal perforation and died of multisystemic organ failure, a mortality
rate of 4.5%. One patient had a partial dehiscence of the laparotomy wound. Three patients developed subcutaneous seromas.
Mean weight losses during the first 4 months were 13, 11, 6 and 5 kg, with a loss of 70% of excess weight in patients approaching
1 year. No patient needs treatment for diarrhea. No serious secondary side-effects have been detected. Conclusion: This operation
appears to result in very satisfactory weight loss, improved quality of life, and a low incidence of complications. 相似文献
12.
介绍了基于Windows3.x环境下,用Delphi开发软件,结合面象对象技术、数据库技术、Windows帮助文件系统技术,开发S12数字程控交换机人机命令信息查询系统的过程和方法.并对超文本技术、面向对象技术、数据库技术进行了阐述.通过试运行,验证了本系统的高速、方便、安全、兼容性好等特点. 相似文献
13.
Hypomanic episodes in two cases involving depressed patients (bipolar II) were observed after admission to an open psychiatric ward. The patients had not exhibited any prior (hypo)manic episodes during outpatient treatment. Thus, manic switching was thought to have been caused by the psychological effects brought on by the change in environment due to hospital admission. Hospital admission was believed to have been an unloading from their stressful lives, given that the affective state of both patients prior to admission was characterized by depression resulting from work-related stress. The close relationship between the patients and the predominantly female nursing staff may have triggered a psychological regression in both patients. These factors appear to have led to the hypomanic switching. 相似文献
14.
15.
UV filters with antagonistic action at androgen receptors in the MDA-kb2 cell transcriptional-activation assay. 总被引:4,自引:0,他引:4
Risheng Ma Bea Cotton Walter Lichtensteiger Margret Schlumpf 《Toxicological sciences》2003,74(1):43-50
The fact that certain ultraviolet (UV) filters used in cosmetics display estrogenic activity prompted us to study potential actions on androgen receptors (AR) in the human breast carcinoma cell line MDA-kb2, which expresses functional endogenous AR and glucocorticoid receptors (GR) and is stably transfected with a luciferase reporter plasmid. Dihydrotestosterone (DHT), methyltrienolone (R1881), methyltestosterone, danazol, and androstenedione increased luciferase activity, with EC50 values between 0.11 nM (R1881), 0.14 nM (DHT), and 73.5 nM (androstenedione). DHT-induced luciferase gene expression was inhibited by nonsteroidal antiandrogens, hydroxyflutamide, flutamide, bicalutamide, and vinclozolin. In contrast, the steroidal AR agonist/antagonist cyproterone actetate showed agonistic activity in the absence and presence of DHT, which was not blocked by hydroxyflutamide and thus seems not to be mediated by AR. GR-mediated activation of luciferase by dexamethasone was 100 times less potent than DHT and was not antagonized by hydroxyflutamide. The cell line was used for screening of UV filters, benzophenone-3 (Bp-3), benzophenone-4, 3-benzylidene camphor, 4-methylbenzylidene camphor, butyl-methoxy-dibenzoylmethane, homosalate (HMS), octyl-dimethyl-PABA, and octyl-methoxycinnamate. Two of these, Bp-3 and HMS, antagonized DHT-induced AR activation below cytotoxic concentrations, with IC50 of 5.57 10-6 M (HMS) and 4.98 10-6 M (Bp-3). None of the eight UV filters displayed agonistic activity when tested alone, but high concentrations of Bp-3 induced an increase of luciferase activity in the presence of dexamethasone, which was not blocked by hydroxyflutamide or the estrogen antagonist, ICI 182,780. These data indicate that the UV filters Bp-3 and HMS possess antiandrogenic activity in vitro in addition to estrogenic activity. 相似文献
16.
青钱柳嫩叶中多糖的含量测定 总被引:4,自引:0,他引:4
目的建立青钱柳叶中多糖含量的测定方法.方法采用苯酚-浓硫酸显色法,于490 nm处测吸光度.结果青钱柳嫩叶中多糖含量为0.65 32%;平均回收率99.03%;r=0.9991.结论方法简便、快速,结果准确、可靠,适合多糖的含量测定. 相似文献
17.
目的:寻求一种鉴定天花粉与其混淆品长萼瓜蒌的有效方法。方法:采用天花粉双边栝楼根以及瓜氨酸作为对照物质,与长萼瓜蒌根同时进行紫外光谱扫描。结果:紫外光谱显示,长萼瓜蒌的水和乙醇溶液在272nm波长处均有最大吸收,而天花粉及瓜氯酸均无此光谱特征,可资鉴别。结论:用紫外光谱法鉴定天花粉与长萼瓜蒌,方法简便可行,结果准确可靠。 相似文献
18.
Current public health advice is that high ultraviolet radiation (UVR) exposure is the primary cause of Malignant Melanoma of skin (CMM), however, despite the use of sun-blocking products incidence of melanoma is increasing. To investigate the UVR influence on CMM incidence worldwide WHO, United Nations, World Bank databases and literature provided 182 country-specific melanoma incidence estimates, daily UVR levels, skin colour (EEL), socioeconomic status (GDP PPP), magnitude of reduced natural selection (Ibs), ageing, urbanization, percentage of European descendants (Eu%), and depigmentation (blonde hair colour), for parametric and non-parametric correlations, multivariate regressions and analyses of variance. Worldwide, UVR levels showed negative correlation with melanoma incidence (“rho” = −0.515, p < 0.001), remaining significant and negative in parametric partial correlation (r = −0.513, p < 0.001) with other variables kept constant. After standardising melanoma incidence for Eu%, melanoma correlation with UVR disappeared completely (“rho” = 0.004, p = 0.967, n = 127). The results question classical views that UVR causes melanoma. No correlation between UVR level and melanoma incidence was present when Eu% (depigmented or light skin type) was kept statistically constant, even after adjusting for other known variables. Countries with lower UVR levels and more Eu% (depigmented or light skin people) have higher melanoma incidence. Critically, this means that individual genetic low skin pigmentation factors predict melanoma risk regardless of UVR exposure levels, and even at low-UVR levels. 相似文献
19.
鸢尾不同产地、采收期总黄酮的含量测定 总被引:1,自引:0,他引:1
采用紫外分光光度法测定了不同产地鸢尾 Iris tectorum Maxim.干燥根茎及南京栽培鸢尾不同采收期药材中总黄酮的含量。其结果为四川峨眉产鸢尾药材总黄酮含量为 4 .5 1% ,四川巫山 5 .73% ,重庆万源6 .86 % ,四川都江堰 6 .94 % ,四川成都 6 .6 4 % ,四川洋县 5 .83% ,四川石柱 6 .4 9% ,四川广元 5 .70 % ,四川涪陵 5 .96 % ,安徽亳州 4 .33% ,江苏南京 4 .38%。南京栽培鸢尾不同采收期药材的总黄酮含量为 1月 5 .4 1% ,2月 4 .36 % ,3月 3.0 3% ,4月 4 .2 8% ,5月 6 .5 9% ,6月 4 .6 9% ,7月 7.17% ,8月 6 .0 3% ,9月 5 .85 % ,10月4 .4 3% ,11月 4 .4 9% ,12月 4 .36 %。不同产地的鸢尾药材以四川都江堰所产含量最高。不同采收期的鸢尾药材以 5月 ,7月 ,8月的含量较高 ,其最佳采收期以 7~ 8月或 5月为宜。 相似文献
20.
目的 探讨枸杞与熏硫枸杞的鉴别方法.方法 将枸杞与熏硫枸杞进行光谱学检测.结果 正品枸杞紫外光谱各个等级吸光度均大于熏硫枸杞;熏硫枸杞的红外光谱在3 337 cm-1、1 041 cm-1处有较强的峰,正品枸杞无此强峰.结论 所选用方法对枸杞的鉴别有参考价值,在中药质量控制方面的应用为枸杞鉴定开辟了新思路. 相似文献