全文获取类型
收费全文 | 447153篇 |
免费 | 40666篇 |
国内免费 | 29755篇 |
专业分类
耳鼻咽喉 | 3329篇 |
儿科学 | 5852篇 |
妇产科学 | 5097篇 |
基础医学 | 50074篇 |
口腔科学 | 7384篇 |
临床医学 | 61717篇 |
内科学 | 62224篇 |
皮肤病学 | 4908篇 |
神经病学 | 22828篇 |
特种医学 | 16190篇 |
外国民族医学 | 244篇 |
外科学 | 41250篇 |
综合类 | 80290篇 |
现状与发展 | 95篇 |
一般理论 | 52篇 |
预防医学 | 32677篇 |
眼科学 | 12554篇 |
药学 | 47650篇 |
503篇 | |
中国医学 | 28007篇 |
肿瘤学 | 34649篇 |
出版年
2024年 | 2184篇 |
2023年 | 6525篇 |
2022年 | 16412篇 |
2021年 | 20982篇 |
2020年 | 16619篇 |
2019年 | 13808篇 |
2018年 | 14214篇 |
2017年 | 13489篇 |
2016年 | 12596篇 |
2015年 | 19358篇 |
2014年 | 24146篇 |
2013年 | 22217篇 |
2012年 | 32906篇 |
2011年 | 37033篇 |
2010年 | 24593篇 |
2009年 | 20069篇 |
2008年 | 25027篇 |
2007年 | 25054篇 |
2006年 | 24261篇 |
2005年 | 23213篇 |
2004年 | 15647篇 |
2003年 | 15139篇 |
2002年 | 12639篇 |
2001年 | 10206篇 |
2000年 | 10012篇 |
1999年 | 10305篇 |
1998年 | 6559篇 |
1997年 | 6478篇 |
1996年 | 5001篇 |
1995年 | 4646篇 |
1994年 | 3946篇 |
1993年 | 2623篇 |
1992年 | 3107篇 |
1991年 | 2706篇 |
1990年 | 2296篇 |
1989年 | 2011篇 |
1988年 | 1726篇 |
1987年 | 1539篇 |
1986年 | 1318篇 |
1985年 | 955篇 |
1984年 | 612篇 |
1983年 | 503篇 |
1982年 | 324篇 |
1981年 | 359篇 |
1980年 | 286篇 |
1979年 | 266篇 |
1978年 | 156篇 |
1977年 | 141篇 |
1976年 | 98篇 |
1974年 | 112篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
51.
Effect of endotoxin and a burn injury on lung and liver lipid peroxidation and catalase activity 总被引:1,自引:0,他引:1
Both endotoxin and a burn alone produce oxidant-induced tissue lipid peroxidation. The endotoxin response is due in large part to hydrogen peroxide. The combination of endotoxin after a burn results in an increased liver, but not lung, oxidant injury. Our purpose was to determine whether the burn oxidant injury inactivated endogenous liver tissue catalase, thereby amplifying a subsequent H2O2 insult. Twenty-six adult sheep were studied. Twelve sheep had a 15% TBS burn. Tissue catalase activity, measured in lung and liver 3 days postburn, was significantly decreased from a control of 3.58 +/- 1.8 and 193 +/- 63, respectively, to 1.72 +/- 0.63 and 148 +/- 33 k(sec-1)/0.5 gram tissue. The addition of endotoxin 3 days postburn resulted in an increase in liver malondialdehyde, MDA, a measure of lipid peroxidation, from a control of 110 +/- 80 to 450 +/- 54 nmol/gram tissue. This value was significantly greater than the 210 +/- 80 nmol/gram tissue seen after endotoxin alone. Lung tissue MDA with burn and endotoxin was 65 +/- 8 compared to 42 +/- 7 for control and 80 +/- 6 nmol/gram for endotoxin alone. We conclude that a decrease in liver catalase activity occurs after a burn. The decrease corresponds to an accentuated oxidant-induced lipid peroxidation after an added endotoxin insult where H2O2 is known to be an etiologic agent. The catalase activity also decreases in postburn lung, but accentuated lung damage was not seen, indicating a variable tissue response from the burn-induced decrease in antioxidant activity.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
52.
53.
Five commercially available nitropolyclyclic aromatic hydrocarbons (nitro-PAH), namely, 4-nitrobiphenyl, 2-nitrofluorene, 9-nitroanthracene, 1-nitropyrene, and 2,7-dinitrofluorene, were exposed under restricted sunlight in the open air. The direct-acting mutagenicities of the samples after an exposure of 45 days were measured in order to compare them with those of the original samples in the Ames Salmonella typhimurium bioassay. It was found that the mutagenicities of some nitro-PAH do not change significantly while the mutagenicities of others increase or decrease after exposure. A preliminary study of nitro-PAH reaction products after exposure using GC, GC/MS, and FT-IR is also reported. 相似文献
54.
关于单结合胆红素水溶性的研究 总被引:4,自引:0,他引:4
目的:进一步研究单结合胆红素(MCB)的水难溶特性及其在病理性胆汁中参与胆红素沉淀和色素性结石形成的作用机制.方法:应用胆红素高效液相色谱分析技术,先从人胆汁中获得结合胆红素,再经分离、制备及纯化得到纯MCB.然后观察其水溶解度并与其它型胆红素比较.结果:在pH7.9,温度37℃接近生理的条件下,MCB的溶解度(558.25±5.96μm)仅为双结合胆红素(DCB)的1/7,比不结合胆红素(UCB)高约44倍并随pH值改变而呈曲线变化.pH7.9时最大;pH4.5时为0;而当pH>9时,反而低于呈离于状态的UCB.结论:MCB虽作为结合型胆红素在胆道生理条件下的不溶性明显高于UCB,但比DCB要低得多;而在胆道病理条件下,其水溶性不但远低于DCB,甚至还不如离子化的UCB,这可能是MCB参与胆红素沉淀及胆色素结石形成的理化基础. 相似文献
55.
56.
Clinical analysis of 107 cases with chemical burns 总被引:1,自引:0,他引:1
G H Li 《中华整形烧伤外科杂志》1990,6(1):34-5, 76
From 1978 to 1987 107 cases of chemical burns were treated. The patients were mainly young and middle age people (83.08%), with mean burned areas 17.8%. The majority of involved parts were low extremities. 57.44% of burned eyes became blind. Mean days in hospital were 43 days. Cure rate was 98.13% and death rate 1.87%. We emphasized that burned wounds must instantly be washed down with water, intoxication resulting from chemical matters must be effectively treated. Diagnosis of depth of burned wound by acids and means of prevention of chemical burns were also discussed. 相似文献
57.
58.
59.
强化婴幼儿奶粉中叶酸的测定 总被引:1,自引:0,他引:1
强化叶酸的奶粉在0.05M K_2HPO_4缓冲液中,经均质,调pH4.5,15000g离心20分钟,其清液调pH4.0,进行CGS树脂离子交换层析,用10ml KClK_2HPO_4洗脱,调pH7.0,进行HPLC测定,采用300x3.9mm ODS反相柱,移动相0.05M K_2HPO+MeOH(91+9),流速1ml/分,紫外检测器波长285nm,灵敏度0.0050D。方法相对标准偏差为±3.3%,回收率为87%,最小检测量为0.02μg/ml。 相似文献
60.
This study investigated the effects of structured group workshops for a population with special needs. Twenty subjects, each with a mild or moderate mental handicap, attended a series of 10 weekly 1-hour music workshops on the structured group playing of a Javanese Gamelan. Twenty subjects formed a non-intervention control group. The experimental hypothesis was that participation in the experimental group would produce significant improvements in musical ability as measured by the Rossi test of musical ability, devised and validated for use in this study. Significant gains in communication skills as measured by the Communication Assessment Profile for Adults with a Mental Handicap (CASP) and self-esteem levels measured by the Khalid semantic differential technique were also postulated. It was also suggested that these gains would be significantly correlated. Results show significant gains in musical ability (instrumental rhythm production: t = 5.67, d.f. = 29, p < 0.01 and simple rhythm production: t = 8.42, d.f. = 29, p < 0.01) and communication skills (t = 4.69, d.f. = 29, p < 0.01). Moreover these results are significantly correlated (r = 0.59, p < 0.05, r = 0.75, p < 0.05, r = 0.56, p < 0.05). A ceiling effect was obtained in the measurement of self-esteem. It is suggested that these gains derive from certain aspects of the musical communicative environment at the workshops. Suggestions for future research involve examining the possible influences on these developments. 相似文献