全文获取类型
收费全文 | 6918篇 |
免费 | 962篇 |
国内免费 | 536篇 |
专业分类
耳鼻咽喉 | 23篇 |
儿科学 | 92篇 |
妇产科学 | 27篇 |
基础医学 | 338篇 |
口腔科学 | 48篇 |
临床医学 | 588篇 |
内科学 | 975篇 |
皮肤病学 | 30篇 |
神经病学 | 176篇 |
特种医学 | 242篇 |
外国民族医学 | 3篇 |
外科学 | 250篇 |
综合类 | 1160篇 |
现状与发展 | 1篇 |
预防医学 | 888篇 |
眼科学 | 93篇 |
药学 | 1014篇 |
3篇 | |
中国医学 | 2310篇 |
肿瘤学 | 155篇 |
出版年
2024年 | 48篇 |
2023年 | 271篇 |
2022年 | 407篇 |
2021年 | 483篇 |
2020年 | 462篇 |
2019年 | 423篇 |
2018年 | 325篇 |
2017年 | 309篇 |
2016年 | 301篇 |
2015年 | 337篇 |
2014年 | 534篇 |
2013年 | 470篇 |
2012年 | 526篇 |
2011年 | 539篇 |
2010年 | 393篇 |
2009年 | 378篇 |
2008年 | 376篇 |
2007年 | 399篇 |
2006年 | 354篇 |
2005年 | 250篇 |
2004年 | 196篇 |
2003年 | 151篇 |
2002年 | 97篇 |
2001年 | 73篇 |
2000年 | 63篇 |
1999年 | 28篇 |
1998年 | 38篇 |
1997年 | 32篇 |
1996年 | 23篇 |
1995年 | 24篇 |
1994年 | 16篇 |
1993年 | 17篇 |
1992年 | 7篇 |
1991年 | 5篇 |
1990年 | 15篇 |
1989年 | 7篇 |
1988年 | 9篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 1篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有8416条查询结果,搜索用时 203 毫秒
1.
采用Mimics对心脏进行三维重构,用3-matic进行模型优化以及模型误差分析,对左心室室壁运动做速度分布假设,基于UDF宏文件对左心室室壁运动编写程序,将血液视为非牛顿流体,采用动网格技术研究不同血压对左心室血液流动的影响。模拟发现当左心室收缩时,压力梯度明显,内部压力减小。当左心室舒张时,内部压力逐渐增高。二尖瓣口处的速率先增大后减小。血压升高,左心室内剪切应力持续增大,极易破坏红细胞结构,产生溶血现象,导致心脏功能紊乱。 相似文献
2.
《European journal of surgical oncology》2022,48(6):1264-1271
BackgroundIn order to avoid excessive treatment of thyroid nodules in the clinic, it is necessary to find a simple and practical analysis method to comprehensively and accurately reflect benign or malignant thyroid nodules. This study aimed to construct and validate a comprehensive and reliable network-based predictive model using a variety of imaging and laboratory criteria for thyroid nodules to stratify the risk of malignancy prior to surgery.MethodsWe retrospectively analyzed data from patients who underwent surgical treatment for thyroid nodules at the Thyroid and Breast Diagnosis and Treatment Center of Weifang Hospital of Traditional Chinese Medicine between January 2018 and December 2020. Binary logical regression analysis was performed to predict whether nodules were malignant or benign. The developmental dataset included 457 patients (January 2018–December 2020). The validation set included separate data points (n = 225, January 2018–December 2020).ResultsIn this study, criteria that showed significant predictive value for malignant nodules included TI-RADS: 4b (p = 0.065); Bethesda IV, Bethesda V, Bethesda VI (P < 0.0001); BRAFV600E mutation (P < 0.0001); Calcitonin>5 pg/ml (p = 0.0037); and FNA-Tg>30 ng/ml (p = 0.0003). A 10-grade risk scoring system was developed. The risk of malignancy risk ranged from 2.06% to 100% and was positively associated with increasing risk grade. The areas under the receiver-operating characteristic curve of the development and validation sets were 0.972 and 0.946, respectively.ConclusionA simple, comprehensive and reliable web-based predictive model was designed using a variety of imaging and laboratory criteria to stratify thyroid nodules by probability of malignancy. 相似文献
3.
4.
《Clinical neurophysiology》2021,132(6):1312-1320
ObjectiveTo investigate the additional value of EEG functional connectivity features, in addition to non-coupling EEG features, for outcome prediction of comatose patients after cardiac arrest.MethodsProspective, multicenter cohort study. Coherence, phase locking value, and mutual information were calculated in 19-channel EEGs at 12 h, 24 h and 48 h after cardiac arrest. Three sets of machine learning classification models were trained and validated with functional connectivity, EEG non-coupling features, and a combination of these. Neurological outcome was assessed at six months and categorized as “good” (Cerebral Performance Category [CPC] 1–2) or “poor” (CPC 3–5).ResultsWe included 594 patients (46% good outcome). A sensitivity of 51% (95% CI: 34–56%) at 100% specificity in predicting poor outcome was achieved by the best functional connectivity-based classifier at 12 h after cardiac arrest, while the best non-coupling-based model reached a sensitivity of 32% (0–54%) at 100% specificity using data at 12 h and 48 h. Combination of both sets of features achieved a sensitivity of 73% (50–77%) at 100% specificity.ConclusionFunctional connectivity measures improve EEG based prediction models for poor outcome of postanoxic coma.SignificanceFunctional connectivity features derived from early EEG hold potential to improve outcome prediction of coma after cardiac arrest. 相似文献
5.
6.
7.
8.
薄层色谱鉴别在历版《中国药典》中的应用经历了从无到有、从少到多的过程;而薄层扫描含量测定在最近几版《中国药典》中的应用比例逐渐降低。随着对中药质量标准体系要求的进一步提高,薄层色谱法的不足之处陆续显现,如仪器普及率低、设备并不简单、结果重复性和稳定性较差、鉴别速度及准确性不及高效液相色谱法、展开剂毒性大等,逐渐不合时宜。在制定中药质量标准时,研究者不应该墨守成规,薄层色谱鉴别也不应该是雷打不动的定性鉴别必备选项。高效液相色谱法具备完全取代薄层色谱法的可行性,薄层色谱法可作为高效液相色谱法的补充。为充分降低检测成本、缩短检测周期、提高鉴别效率,笔者建议中药质量标准体系应该大幅减少薄层色谱鉴别方法的应用,增加高效液相特征图谱鉴定,尽量做到“一个条件,一张图谱”;除非确有必要,《中国药典》等国家质量标准体系应将薄层色谱鉴别作为推荐方法,而非强制标准。 相似文献
9.
《Journal of vascular and interventional radiology : JVIR》2019,30(10):1549-1554
PurposeTo identify factors independently associated with disease recurrence after venoplasty and stent placement for May–Thurner syndrome (MTS).Materials and MethodsFifty-nine consecutive patients (age, 47 y ± 15; 93% female) were identified who had undergone endovascular stent placement for MTS. Patient charts were reviewed for demographic data, risk factors for venous thrombosis, comorbidities, and venous inflow or outflow at first follow-up (3 wk to 6 mo after treatment). Logistic regression was used to identify independent predictors of symptom recurrence or repeat intervention, and multivariate analysis of variance and receiver operator characteristic curve analysis were used to assess relationships between degrees of in-stent stenosis and other variables in the 73% of patients with available cross-sectional imaging. Median follow up was 20.7 months (interquartile range, 4.7–49.5 mo).ResultsAll procedures were technically successful. Disease recurrence, defined as symptom recurrence following initial postprocedural resolution, was observed in 38% of patients. No preprocedural variable was found to be independently predictive of disease recurrence; however, poor venous inflow or outflow were both strongly associated with recurrent disease, with adjusted odds ratios and 95% confidence intervals of 38.02 (3.76–384.20; P = .002) and 7.00 (1.15–42.71; P = .04), respectively. Higher degrees of in-stent stenosis were also associated with symptom recurrence, with an area under the curve of 0.93 (P = .000002) and 39%–41% stenosis being 78%–83% sensitive and 88%–92% specific for symptom recurrence.ConclusionsThese results suggest that cross-sectional imaging can help differentiate patients in whom closer follow-up may be warranted after venoplasty and stent placement for MTS and also guide counseling regarding prognosis. 相似文献
10.
《中医科学杂志(英文)》2020,7(3):233-244
ObjectiveThe objective of this study was to verify the lipid-lowering effect of Juhe Fang extract (JHFE) and to determine its characteristic chemical profile in vitro and in vivo.MethodsA hyperlipidemia model was established by feeding mice a high-fat diet (HFD). After treatment for 30 days, serum total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) levels were measured with an automatic biochemistry analyzer. The components from JHFE obtained from in vivo and in vitro experiments were investigated using an UPLC-Q Exactive-Orbitrap MS/MS.ResultsThe TC, TG, and LDL-C in the serum significantly decreased and the HDL-C significantly increased after JHFE treatment. A total of 95 compounds from JHEF including 15 phenolic acids (PA), 4 phenylethanoid glycosides (PG), 24 flavonoids (F), 14 triterpenoids (T), 10 diterpenoid glycosides (D), 18 alkaloids (A) and 10 others (O) were identified. Trigonelline was discovered for the first time in a herbal medicine of Juhe Fang. Furthermore, 68 compounds were identified in vivo including 28 prototype compounds and 40 metabolites. The metabolic characteristics of these components were revealed including identification of new metabolites of 4-hydroxyphenyl ethyl-8-O-[α-L- arabinopyranosyl-(1 → 6)]-β-D-glucopyranoside (PEG) and lirinidine. A total of 43 components from JHFE were absorbed and/or metabolized. The contribution rate of each type of chemical component from JHFE to its lipid-lowering effect from high to low were A, F, PG, PA, D and T.ConclusionThe results of this study showed that JHFE demonstrated a significant lipid-lowering effect in a high-fat diet (HFD)-induced hyperlipidemia mouse model. Specific types of PA, PG, F, D, T and A formed the pharmaceutical architecture of the lipid-lowering effect of JHFE. This study should prove useful for clarifying the components responsible for the lipid-lowering effect of JHFE and provide a basis for precision quality control research. 相似文献