全文获取类型
收费全文 | 84520篇 |
免费 | 7476篇 |
国内免费 | 5491篇 |
专业分类
耳鼻咽喉 | 876篇 |
儿科学 | 936篇 |
妇产科学 | 1266篇 |
基础医学 | 10963篇 |
口腔科学 | 1436篇 |
临床医学 | 11176篇 |
内科学 | 12722篇 |
皮肤病学 | 1129篇 |
神经病学 | 4682篇 |
特种医学 | 3318篇 |
外国民族医学 | 53篇 |
外科学 | 8746篇 |
综合类 | 10786篇 |
现状与发展 | 21篇 |
一般理论 | 22篇 |
预防医学 | 5261篇 |
眼科学 | 3020篇 |
药学 | 8718篇 |
67篇 | |
中国医学 | 4219篇 |
肿瘤学 | 8070篇 |
出版年
2024年 | 261篇 |
2023年 | 1244篇 |
2022年 | 3255篇 |
2021年 | 4181篇 |
2020年 | 3065篇 |
2019年 | 2949篇 |
2018年 | 3124篇 |
2017年 | 2608篇 |
2016年 | 2735篇 |
2015年 | 3907篇 |
2014年 | 4844篇 |
2013年 | 4316篇 |
2012年 | 6398篇 |
2011年 | 6827篇 |
2010年 | 4215篇 |
2009年 | 3199篇 |
2008年 | 4450篇 |
2007年 | 4272篇 |
2006年 | 4361篇 |
2005年 | 4207篇 |
2004年 | 2880篇 |
2003年 | 2622篇 |
2002年 | 2157篇 |
2001年 | 1853篇 |
2000年 | 1837篇 |
1999年 | 2114篇 |
1998年 | 1313篇 |
1997年 | 1283篇 |
1996年 | 963篇 |
1995年 | 915篇 |
1994年 | 769篇 |
1993年 | 491篇 |
1992年 | 615篇 |
1991年 | 522篇 |
1990年 | 486篇 |
1989年 | 432篇 |
1988年 | 381篇 |
1987年 | 311篇 |
1986年 | 256篇 |
1985年 | 215篇 |
1984年 | 138篇 |
1983年 | 92篇 |
1982年 | 44篇 |
1981年 | 52篇 |
1980年 | 29篇 |
1979年 | 63篇 |
1978年 | 27篇 |
1974年 | 29篇 |
1969年 | 19篇 |
1968年 | 21篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
J Sun 《中华心血管病杂志》1991,19(6):375-7, 398
The hemodynamic changes of 15 cases during external counterpulsation with left and right cardiac catheters were reported. The results showed that the diastolic pressure at the root of the aorta was remarkably increased, the peak value (countercurrent pressure) was 8.02 +/- 2.05 kPa higher than the diastolic pressure before counterpulsation; the aortic systolic pressure during counterpulsation was slightly decreased with a mean value of 0.81 kPa; there was no apparent change in the central venous pressure and pulmonary arterial pressure; pulmonary arterial wedge pressure was slightly reduced during counterpulsation. All the above data are useful in showing the improvement of cardiac and brain perfusion volume and clarifying its mechanism. 相似文献
52.
Koji Tomobe Hajime Fujii Buxiang Sun Hiroshi Nishioka Okezie I Aruoma 《Biomedicine & Pharmacotherapy》2007,61(7):427-434
Oligonol is produced from the oligomerization of polyphenols (typically proanthocyanidin from a variety of fruits such as lychees, grapes, apples, persimmons, etc.) and contains catechin-type monomers and oligomers of proanthocyanidins. The ability of Oligonol to affect infection-dependent eye inflammation, locomotion and longevity in senescence-accelerated prone mice (SAMP8) (a model of senescence acceleration and geriatric disorders with increased oxidative stress and neuronal deficit) was investigated. Oligonol (60mg/kg) significantly modulated the extent of inflammation scores in the eye of SAMP8 mice. Examination of the mice indicated infection with mouse hepatitis virus and pinworm (Syphacia obvelata) in both males and females and with the intestinal protozoa (trichomonad) in males. A comparison of the two groups (using log-rank test) and the difference in the mean life span between groups (using Student's t-test) indicated significant differences in survival (p=0.043) and the mean life span (p=0.033) in male SAMP8 mice. Oligonol increased the mean life span and this was statistically significant. In the open-field locomotive test, the 7-week-old SAMP8 mice crossed more than 40 partitioned lines in 1min. At 48-week-old control untreated male SAMP8 crossed 2 lines. The Oligonol-treated 48-week-old male SAMP8 mice crossed 17 lines however. The improved locomotive activity was statistically significant even after 36weeks in the Oligonol-treated male SAMP8 but this was not the case throughout the time course of the study in the Oligonol-treated female SAMP8. Thus Oligonol treatment to SAMP8 mice modulated the severity of infection-dependent inflammation, prolonged life-span and significantly improved locomotive activity indicating potential benefit to aging-associated diseases such as Alzheimer's or Parkinson's diseases. This presents potential for further research to define infection-dependent inflammation associated with degenerative conditions and the molecular mechanism of dietary antioxidant protection. 相似文献
53.
H. W. Chu S. Balzar J. Y. Westcott J. B. Trudeau Y. Sun D. J. Conrad S. E. Wenzel 《Clinical and experimental allergy》2002,32(11):1558-1565
BACKGROUND: Although 15(S)-hydroxyeicosatetraenoic acid (15(S)-HETE), a product of 15-lipoxygenase (15-LO), may be involved in mild to moderate asthma, little is known about its potential roles in severe asthma. OBJECTIVES: This study was performed to evaluate 15(S)-HETE levels in bronchoalveolar lavage fluid (BALF) from severe asthmatics with and without airway eosinophils and from the control groups. In addition, 15-LO protein expression was examined in endobronchial biopsy, while its expression and activation were evaluated in BAL cells. RESULTS: While 15(S)-HETE levels in BALF were significantly higher in all severe asthmatics than normal subjects, severe asthmatics with airway eosinophils had the highest levels compared with mild, moderate asthmatics and normal subjects. 15(S)-HETE levels were associated with tissue eosinophil numbers, sub-basement membrane thickness and BALF tissue inhibitor of metalloproteinase-1 levels, and were accompanied by increased 15-LO expression in bronchial epithelium. In addition, activation of 15-LO was suggested by the increased proportion of 15-LO in the cytoplasmic membrane of alveolar macrophages from severe asthmatics. CONCLUSION: The data suggest that severe asthmatics with persistent airway eosinophils manifest high levels of 15(S)-HETE in BALF, which may be associated with airway fibrosis. It is likely that 15-LO expression and activation by airway cells explain the increased 15(S)-HETE levels. 相似文献
54.
教师常常偏爱成绩好的学生,而对学习困难学生则在情感上、精力上和研究上投入不够。对学习困难学生的认识往往集中在他们身上的缺陷,而忽视了他们具有的学习潜能。教学实践证明,合理的施教是开发其潜能、促进其转化的关键。 相似文献
55.
This paper reports the treatment results of 50 symptomatic females who had clinical features of squamous papillae and histologic evidence of koilocytosis. Either a carbon dioxide laser or a single application of trichloroacetic acid (TCA) was used to treat these patients. All of the patients were alternately and prospectively randomized into one of two groups. Twenty-three of the 25 women treated by laser and 10 of the 25 women treated by TCA had resolution of either the symptoms or the vulvar lesions in a follow-up period ranging from six to 22 months. Hence, we were able to control the symptoms and lesions in 92% of the women following initial laser treatment and 40% of the women following a single application of TCA. In addition, cosmetic results were satisfactory, and complications were minimal in the laser-treated group of patients. However, human papillomavirus DNA was still detected three to four weeks after treatment in 24% of the women treated by laser and 64% of the women treated by TCA. Whether they are at a higher risk of recurrence as compared to those without detectable viral DNA remains to be determined. 相似文献
56.
The effects of combined use of earthworm extract(912)and HpD-laser on the produc-tion of reactive oxygen and the biosynthesis of DNA in S_(180) tumor cells were studied throughchemiluminescence measurement and[~3H]-TdR incorporation assay.The results showed that as com-pared with the control,the intensity of chemiluminescence emitted by tumor cells treatedsimultaneously with 912 and HpD-laser was enhanced more than ten-folds,while that treated with912 or HpD-laser alone was increased only 2~4 folds.The[~3H]-TdR incorporation into tumorcells of the former group was inhibited upto 74.1%,and that of the latter groups decreased onlyby 42.2% and 40.0%,respectively.In accordance with these biochemical changes,the ultrastructuraldamage of tumor cells of the former,combinedly treated group appeared to be the most serious.This suggests an additive effect of 912 with HpD-laser on tumor cells.In addition,if free radicalscavengers,such as catalase and superoxide dismutase,were added to the reaction systembefore chemiluminescence assay,the luminescent enhancement effect mentioned above was dramaticallyalleviated,implying the presence of O_2~ and H_2O_2 in the system.Therefore,as to the toxic effecton tumor cells,912 and HpD-laser are not only additive in efficiency,but also similar in theunderlying mechanism of action. 相似文献
57.
58.
We investigated airway response to propranolol in 48 asthmatics, 17 subjects with chronic bronchitis and 19 normal subjects. The positive rate for propranolol challenge was 93.8% in asthma group, 5.9% in chronic bronchitis group while none in normal group had positive response. The challenge was highly reproducible, and it had few side-effects. This indicated that the challenge was specific and sensitive in diagnosis of asthma, it was a safe, reliable method of measuring non-specific airway responsiveness. Furthermore we also demonstrated that PC20 for propranolol did not relate to PC20 for methacholine, and that the calibre of airway did not significantly influence the airway response to propranolol. 相似文献
59.
Shuei-Tu Chen Ko-Hsiu Lu Hai-Lun Sun Wen-Tung Chang Ko-Huang Lue Ming-Chih Chou 《Pediatric allergy and immunology》2006,17(1):49-54
Leukotriene receptor antagonists (LTRAs) were recently added to the method of treating allergic rhinitis (AR). However, in children under 6 yr old, there has been no study about its efficacy in treating AR. We aim to compare the clinical efficacy of montelukast, cetirizine and placebo in the treatment of children from 2 to 6 yr old with perennial allergic rhinitis (PAR), to see if there are any significant differences. Sixty children were selected and treated with montelukast, or cetirizine, or placebo once daily. The efficacy of the three agents was compared with the Pediatric Rhinoconjunctivitis Quality of Life Questionnaire (PRQLQ) and Total Symptom Score (TSS) by diary. In addition, we also examined serum IgE, serum eosinophil cationic protein (ECP), blood eosinophil counts, nasal airway resistance (NAR) and eosinophil percentage in nasal smears. The results revealed that both montelukast and cetirizine were significantly efficacious compared with placebo in NAR, eosinophil percentage in nasal smears, PRQLQ, TSS and all symptom items except nasal itching, throat itching and tearing. For nasal itching, only cetirizine was significantly efficacious. On the other hand, for night sleep quality, montelukast was significantly superior to cetirizine. 相似文献
60.
The use of biological markers in toxicology 总被引:1,自引:0,他引:1