全文获取类型
收费全文 | 44294篇 |
免费 | 3888篇 |
国内免费 | 3038篇 |
专业分类
耳鼻咽喉 | 354篇 |
儿科学 | 671篇 |
妇产科学 | 626篇 |
基础医学 | 5506篇 |
口腔科学 | 704篇 |
临床医学 | 5872篇 |
内科学 | 7279篇 |
皮肤病学 | 461篇 |
神经病学 | 2773篇 |
特种医学 | 1379篇 |
外国民族医学 | 17篇 |
外科学 | 4875篇 |
综合类 | 6769篇 |
现状与发展 | 5篇 |
一般理论 | 7篇 |
预防医学 | 2675篇 |
眼科学 | 1213篇 |
药学 | 4422篇 |
31篇 | |
中国医学 | 1856篇 |
肿瘤学 | 3725篇 |
出版年
2024年 | 140篇 |
2023年 | 667篇 |
2022年 | 1709篇 |
2021年 | 2182篇 |
2020年 | 1596篇 |
2019年 | 1532篇 |
2018年 | 1596篇 |
2017年 | 1373篇 |
2016年 | 1281篇 |
2015年 | 1913篇 |
2014年 | 2385篇 |
2013年 | 2153篇 |
2012年 | 3222篇 |
2011年 | 3447篇 |
2010年 | 2058篇 |
2009年 | 1683篇 |
2008年 | 2329篇 |
2007年 | 2361篇 |
2006年 | 2228篇 |
2005年 | 2238篇 |
2004年 | 1526篇 |
2003年 | 1476篇 |
2002年 | 1247篇 |
2001年 | 1104篇 |
2000年 | 1122篇 |
1999年 | 1229篇 |
1998年 | 655篇 |
1997年 | 713篇 |
1996年 | 528篇 |
1995年 | 478篇 |
1994年 | 411篇 |
1993年 | 296篇 |
1992年 | 365篇 |
1991年 | 319篇 |
1990年 | 270篇 |
1989年 | 238篇 |
1988年 | 219篇 |
1987年 | 188篇 |
1986年 | 168篇 |
1985年 | 123篇 |
1984年 | 69篇 |
1983年 | 78篇 |
1982年 | 47篇 |
1981年 | 53篇 |
1980年 | 29篇 |
1979年 | 44篇 |
1978年 | 20篇 |
1977年 | 17篇 |
1974年 | 18篇 |
1973年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
101.
102.
Ⅰ、Ⅲ型前胶原基因第2外显子核酶对靶RNA的体外切割活性的研究 总被引:5,自引:0,他引:5
目的 体外研究锤头型α1Ⅰ型及Ⅲ型前胶原基因第2外显子片段核酶对各自靶RNA分子的切割活性及反应条件。同时观察两反义核酶对瘢痕中成纤维细胞胶原合成的影响。方法 将含α1Ⅰ型及Ⅲ型前胶原基因第2外显子片段的重组质粒(pT-Ⅰ、pT-Ⅲ),经体外^32P标记转录后形成产物靶RNA。同时将含特异性核酶基因的重组质粒(pT-gⅠ、pT-gⅢ)进行非标记的体外转录,产物(核酶)与各自的^32P-靶RNA按不同的条件混和反应,电泳后放射自显影观察结果。将构建好的核酶以脂质体包裹后导入培养的成纤维细胞内,采用图像分析法观察核酶对成纤维细胞Ⅰ型、Ⅲ型胶原蛋白mRNA合成的影响。结果 两种核酶在37℃、42℃均能有效切割各自的靶RNA,对Mg^2 浓度的要求范围较宽(10~20mmol/L);反应温度从65℃逐渐降至并维持在37℃的条件下核酶切割活性显提高。Ⅰ、Ⅲ型胶原蛋白mRNA的表达明显降低,胶原蛋白生成降低,胶原生成明显受抑制。结论 针对α1Ⅰ型及Ⅲ型前胶原基因第2外显子片段的核酶能有效地在体外对靶RNA进行切割并能有效地抑制瘢痕中成纤维细胞胶原的合成。 相似文献
103.
BACKGROUND AND PURPOSE: Health-related quality of life (HRQOL) is primarily an assessment of how domains of life are affected by health. This study investigated the factors influencing HRQOL of Taiwanese patients with bronchial asthma. METHODS: A cross-sectional study was conducted to assess the factors influencing HRQOL. The sample consisted of 242 outpatients with bronchial asthma. The Chinese language version of the St. George's Respiratory Questionnaire was used to measure HRQOL. Data were analyzed using simple regression and multiple regression. RESULTS: Age, marital status, level of education, asthma severity, peak expiratory flow, and previous hospital admissions were found to be predictors of HRQOL. Gender, duration of disease, and history of emergency visits were not correlated with HRQOL. The variables entered in the HRQOL model accounted for 17.4% of the total variance (adjusted R(2)). The regression coefficients indicated that the mean scores increased 7.68 in patients with moderate to severe disease severity, and increased 7.34 in patients with a history of hospital admissions. The mean scores decreased 7.60 in married patients. CONCLUSION: This study found that marital status, asthma severity, and history of hospital admissions were major predictors of HRQOL in Taiwanese patients with bronchial asthma. 相似文献
104.
六神丸及其加味抗急性白血病的实验研究 总被引:4,自引:0,他引:4
本研究从血象、骨髓、病理、骨髓细胞增殖动力学的角度证明:六神丸具有明显的抑制和杀伤实验白血病小鼠(L7212)白血病细胞的作用(主要机理类似细胞毒剂),具有缓解、减轻白血病细胞对肝脾浸润,明显延长白血病小鼠生存期的作用;六神丸加味(加用清热解毒方、活血化淤方、益气养阴方、补气养血方、补肾方)和六神丸具有明显的协同作用。 相似文献
105.
本文测定了对照组及两个萘普生(前列腺素合成酶抑制剂)处理组大鼠着床期宫内PGF2α的含量。结果表明,对照组、萘普生低剂量组(2mg/kg体重)和高剂量组(20mg/kg体重)的PGF2α含量分别为6.71±0.93、2.19±0.34和1.01±0.18ng/100g组织(三组间P<0.01)。同时,还观察到在本实验条件下,萘普生无明显干扰节育器抗生育作用,药物本身亦未呈现显著抗生育活性。 相似文献
106.
107.
108.
A nonlinear forecast system for the sea surface temperature (SST) anomalies over the whole tropical Pacific has been developed using a multi-layer perceptron neural network approach, where sea level pressure and SST anomalies were used as predictors to predict the five leading SST principal components at lead times from 3 to 15 months. Relative to the linear regression (LR) models, the nonlinear (NL) models showed higher correlation skills and lower root mean square errors over most areas of the domain, especially over the far western Pacific (west of 155 degrees E) and the eastern equatorial Pacific off Peru at lead times longer than 3 months, with correlation skills enhanced by 0.10-0.14. Seasonal and decadal changes in the prediction skills in the NL and LR models were also studied. 相似文献
109.
Steven N Singh X Charlene Tang Bramah N Singh Paul Dorian Domenic J Reda Crystal L Harris Ross D Fletcher Satish C Sharma J Edwin Atwood Alan K Jacobson H Daniel Lewis Becky Lopez Dennis W Raisch Michael D Ezekowitz 《Journal of the American College of Cardiology》2006,48(4):721-730
OBJECTIVES: The purpose of this study was to determine quality of life (QOL) and exercise performance (EP) in patients with persistent atrial fibrillation (AF) converted to sinus rhythm (SR) compared with those remaining in or reverting to AF. BACKGROUND: Restoration of SR in patients with AF improving QOL and EP remains controversial. METHODS: Patients with persistent AF were randomized double-blind to amiodarone, sotalol, or placebo. Those not achieving SR at day 28 were cardioverted and classified into SR or AF groups at 8 weeks (n = 624) and 1 year (n = 556). The QOL (SF-36), symptom checklist (SCL), specific activity scale (SAS), AF severity scale (AFSS), and EP were assessed. RESULTS: Favorable changes were seen in SR patients at 8 weeks in physical functioning (p < 0.001), physical role limitations (p = 0.03), general health (p = 0.002), and vitality (p < 0.001), and at 1 year in general health (p = 0.007) and social functioning (p = 0.02). Changes in the scores for SCL severity (p = 0.01), functional capacity (p = 0.003), and AFSS symptom burden (p < 0.001) at 8 weeks and in SCL severity (p < 0.01) and AF symptom burden (p < 0.001) at 1 year showed significant improvements in SR versus AF. Symptomatic patients were more likely to have improvement. The EP in SR versus AF was greater from baseline to 8 weeks (p = 0.01) and to 1 year (p = 0.02). The EP correlated with physical functioning and functional capacity except in the AF group at 1 year. CONCLUSIONS: In patients with persistent AF, restoration and maintenance of SR was associated with improvements in QOL measures and EP. There was a strong correlation between QOL measures and EP. 相似文献
110.
Clinical applications of mifepristone. 总被引:4,自引:0,他引:4
Mifepristone is a progesterone antagonist that has been studied for a number of clinical applications. It is a well-known abortifacient that is effective for both first- and second-trimester medical abortion when used with a prostaglandin analog. It is also an effective cervical priming agent that can be used to soften the cervix before surgical evacuation. Its clinical efficacy as an emergency contraception has been proven. Other applications including treatment for fibroids, endometriosis and various cancers have been explored. However, its association with abortion limits the applications of mifepristone in many of these areas. 相似文献