全文获取类型
收费全文 | 61361篇 |
免费 | 5410篇 |
国内免费 | 4075篇 |
专业分类
耳鼻咽喉 | 564篇 |
儿科学 | 806篇 |
妇产科学 | 1074篇 |
基础医学 | 7829篇 |
口腔科学 | 983篇 |
临床医学 | 7874篇 |
内科学 | 9571篇 |
皮肤病学 | 702篇 |
神经病学 | 3651篇 |
特种医学 | 2278篇 |
外国民族医学 | 54篇 |
外科学 | 6215篇 |
综合类 | 8252篇 |
现状与发展 | 19篇 |
一般理论 | 3篇 |
预防医学 | 4107篇 |
眼科学 | 1675篇 |
药学 | 6432篇 |
63篇 | |
中国医学 | 3081篇 |
肿瘤学 | 5613篇 |
出版年
2024年 | 184篇 |
2023年 | 960篇 |
2022年 | 2462篇 |
2021年 | 3202篇 |
2020年 | 2322篇 |
2019年 | 2172篇 |
2018年 | 2278篇 |
2017年 | 1931篇 |
2016年 | 1917篇 |
2015年 | 2761篇 |
2014年 | 3390篇 |
2013年 | 2852篇 |
2012年 | 4464篇 |
2011年 | 4938篇 |
2010年 | 2991篇 |
2009年 | 2273篇 |
2008年 | 3146篇 |
2007年 | 3174篇 |
2006年 | 3164篇 |
2005年 | 3141篇 |
2004年 | 2137篇 |
2003年 | 2076篇 |
2002年 | 1796篇 |
2001年 | 1253篇 |
2000年 | 1322篇 |
1999年 | 1415篇 |
1998年 | 936篇 |
1997年 | 882篇 |
1996年 | 675篇 |
1995年 | 616篇 |
1994年 | 509篇 |
1993年 | 331篇 |
1992年 | 418篇 |
1991年 | 369篇 |
1990年 | 328篇 |
1989年 | 285篇 |
1988年 | 295篇 |
1987年 | 240篇 |
1986年 | 232篇 |
1985年 | 182篇 |
1984年 | 127篇 |
1983年 | 98篇 |
1982年 | 54篇 |
1981年 | 52篇 |
1980年 | 40篇 |
1979年 | 97篇 |
1978年 | 41篇 |
1975年 | 40篇 |
1974年 | 52篇 |
1973年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Jianhui Su Chaoyang Ma Chengxiang Liu Chuanzhong Gao Rongjing Nie 《International journal of food sciences and nutrition》2016,67(1):20-28
This study investigated the hypocholesterolaemic effects of bitter melon aqueous extracts (BMAE) in vitro, the inhibitory effects of BMAE on pancreatic cholesterol esterase (CEase) and incorporation of cholesterol into micelles were investigated. BMAE decreased the in vitro micellar solubility of cholesterol in a dose-dependent manner. The conformation of CEase was investigated by means of circular dichroism (CD) and fluorescence. The result revealed the decrease of α-helix contents, increase of β-sheet and exposure of aromatic amino acid residuals. The incorporation of cholesterol into micelles was inhibited by BMAE. A complex was observed by transmission electron microscopy (TEM), which indicated interaction between cholesterol and BMAE. The result revealed that BMAE can play a role in decreased intestinal cholesterol absorption via inhibition of CEase, and of micelle formation. 相似文献
2.
Shengxuan Cao Chen Wang Xin Ma Xu Wang Jiazhang Huang Chao Zhang Li Chen Xiang Geng Kan Wang 《Journal of orthopaedic research》2019,37(8):1860-1867
Patients with mechanic ankle instability experience increased tibiotalar and subtalar joint laxity. However, in vivo joint kinematics in functional ankle instability (FAI) patients and lateral ankle sprain (LAS) copers, especially during dynamic activities, are poorly understood. Ten FAI patients, 10 LAS copers, and 10 healthy controls were included in this study. A dual fluoroscopic imaging system was used to analyze the tibiotalar and subtalar joint kinematics during stair descent. Five key poses of stair descent were analyzed. Kinematic data from six degrees of freedom were calculated utilizing a solid modeling software. The range of motion and joint positions in each degree of freedom were compared among the three groups. The tibiotalar joints of FAI patients and LAS copers were significantly more inverted than those of healthy controls during the foot strike (p = 0.016, = 0.264). The subtalar joints of FAI patients were significantly more anteriorly translated (pose 2, p = 0.003, = 0.352; pose 3, p < 0.001, = 0.454; pose 4, p = 0.004, = 0.334), inverted (pose 4, p = 0.027, = 0.234; pose 5,p = 0.034, = 0.221), and externally rotated (pose 4, p = 0.037, = 0.217; pose 5; p = 0.004, = 0.331) than those of healthy controls during the mid‐stance and the heel off. The FAI patients showed excessive tibiotalar inversion and subtalar joint hypermobility during stair descent. Meanwhile, the LAS copers maintained subtalar joint stability, and only showed excessive tibiotalar inversion in foot strike. These data provide insight into the mechanisms behind the development of FAI after initial LAS. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:1860–1867, 2019 相似文献
3.
4.
Inflammation but not obesity or insulin resistance is associated with increased plasma fibroblast growth factor 23 concentration in the elderly 下载免费PDF全文
5.
Parallel enzyme‐linked immunosorbent assay screening for human immunodeficiency virus among blood donors in five Chinese blood centres: a retrospective analysis 下载免费PDF全文
6.
7.
目的应用免疫组织化学染色的方法检测硒蛋白P在直肠癌组织中的表达,以探讨其与直肠癌发生的关系及临床意义。方法收集山西大医院2013年6月至2014年5月间行手术治疗并经病理证实的60例直肠癌组织、40例直肠腺瘤组织、40例正常直肠组织,应用SABC法检测上述组织中硒蛋白P的表达情况,结果依据阳性细胞百分率和染色强度进行评价,三组间样本率的比较采用无序行×列表?2检验(α=0.05),两组间样本率的比较采用独立样本?2检验(α=0.016 7),硒蛋白的表达与直肠癌临床病理参数的关系采用四格表?2检验(α=0.05)进行分析。结果硒蛋白P在正常直肠组织、直肠腺瘤组织、直肠癌组织中的表达阳性率分别为82.5%(33/40)、70.0%(28/40)、45.0%(27/60),组间差异有统计学意义(?2=15.680,P<0.001),癌组织与正常组织、腺瘤组织间差异显著(?2=14.063,P<0.001;?2=6.061,P=0.015);硒蛋白的表达与肿瘤大小、是否浸润浆膜有关(P<0.05),与性别、年龄、淋巴结有无转移、肿瘤细胞分化程度、TNM分期无关(P>0.05)。结论硒蛋白在直肠癌中低表达,对直肠癌的发生发展具有重要作用,有望为直肠癌的治疗提供新思路。 相似文献
8.
Konrad Matyja Anna Małachowska-Jutsz Anna K. Mazur Kazimierz Grabas 《Ecotoxicology (London, England)》2016,25(5):924-939
Dehydrogenase activity is frequently used to assess the general condition of microorganisms in soil and activated sludge. Many studies have investigated the inhibition of dehydrogenase activity by various compounds, including heavy metal ions. However, the time after which the measurements are carried out is often chosen arbitrarily. Thus, it can be difficult to estimate how the toxic effects of compounds vary during the reaction and when the maximum of the effect would be reached. Hence, the aim of this study was to create simple and useful mathematical model describing changes in dehydrogenase activity during exposure to substances that inactivate enzymes. Our model is based on the Lagergrens pseudo-first-order equation, the rate of chemical reactions, enzyme activity, and inactivation and was created to describe short-term changes in dehydrogenase activity. The main assumption of our model is that toxic substances cause irreversible inactivation of enzyme units. The model is able to predict the maximum direct toxic effect (MDTE) and the time to reach this maximum (TMDTE). In order to validate our model, we present two examples: inactivation of dehydrogenase in microorganisms in soil and activated sludge. The model was applied successfully for cadmium and copper ions. Our results indicate that the predicted MDTE and TMDTE are more appropriate than EC50 and IC50 for toxicity assessments, except for long exposure times. 相似文献
9.
10.