全文获取类型
收费全文 | 194112篇 |
免费 | 5941篇 |
国内免费 | 2655篇 |
专业分类
耳鼻咽喉 | 1781篇 |
儿科学 | 6238篇 |
妇产科学 | 2822篇 |
基础医学 | 21614篇 |
口腔科学 | 4967篇 |
临床医学 | 14458篇 |
内科学 | 32721篇 |
皮肤病学 | 3117篇 |
神经病学 | 10472篇 |
特种医学 | 4648篇 |
外国民族医学 | 1篇 |
外科学 | 27850篇 |
综合类 | 16738篇 |
现状与发展 | 2篇 |
一般理论 | 4篇 |
预防医学 | 12326篇 |
眼科学 | 3522篇 |
药学 | 23104篇 |
186篇 | |
中国医学 | 11017篇 |
肿瘤学 | 5120篇 |
出版年
2022年 | 1720篇 |
2021年 | 3429篇 |
2020年 | 2213篇 |
2019年 | 13263篇 |
2018年 | 12870篇 |
2017年 | 6397篇 |
2016年 | 2102篇 |
2015年 | 2168篇 |
2014年 | 4815篇 |
2013年 | 6505篇 |
2012年 | 4965篇 |
2011年 | 5063篇 |
2010年 | 4121篇 |
2009年 | 3724篇 |
2008年 | 4190篇 |
2007年 | 5539篇 |
2006年 | 5346篇 |
2005年 | 5108篇 |
2004年 | 4095篇 |
2003年 | 3919篇 |
2002年 | 3746篇 |
2001年 | 3653篇 |
2000年 | 3807篇 |
1999年 | 3431篇 |
1998年 | 3417篇 |
1997年 | 2714篇 |
1996年 | 2548篇 |
1995年 | 2918篇 |
1994年 | 2729篇 |
1993年 | 2180篇 |
1992年 | 1732篇 |
1991年 | 1699篇 |
1990年 | 1431篇 |
1989年 | 1153篇 |
1988年 | 1190篇 |
1987年 | 1131篇 |
1986年 | 966篇 |
1985年 | 5555篇 |
1984年 | 7366篇 |
1983年 | 5878篇 |
1982年 | 6349篇 |
1981年 | 5752篇 |
1980年 | 4944篇 |
1979年 | 4994篇 |
1978年 | 4094篇 |
1977年 | 3067篇 |
1976年 | 3549篇 |
1975年 | 2740篇 |
1974年 | 2532篇 |
1973年 | 2238篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Guo-Quan Shi Huajun Zhu & Zhen-Guo Yan 《Communications In Computational Physics》2022,31(4):1215-1241
A priori subcell limiting approach is developed for high-order flux reconstruction/correction procedure via reconstruction (FR/CPR) methods on two-dimensional unstructured quadrilateral meshes. Firstly, a modified indicator based on
modal energy coefficients is proposed to detect troubled cells, where discontinuities
exist. Then, troubled cells are decomposed into nonuniform subcells and each subcell has one solution point. A second-order finite difference shock-capturing scheme
based on nonuniform nonlinear weighted (NNW) interpolation is constructed to perform the calculation on troubled cells while smooth cells are calculated by the CPR
method. Numerical investigations show that the proposed subcell limiting strategy on
unstructured quadrilateral meshes is robust in shock-capturing. 相似文献
2.
3.
目的 筛选荔枝草治疗急性咽炎的有效部位,研究治疗急性咽炎的作用机制,为荔枝草资源的药食两用开发提供理论依据。方法 通过二甲苯致小鼠耳肿胀试验筛选荔枝草抗炎有效部位,采用氨水刺激喉部法建立大鼠急性咽炎模型,通过行为学观察、ELISA双抗夹心检测、病理形态学观察和咽部组织蛋白表达研究乙酸乙酯部位对大鼠急性咽炎的治疗效果。结果 荔枝草乙酸乙酯提取物对二甲苯致小鼠耳肿胀有明显的抑制作用,氨水刺激建立的急性咽炎模型符合急性咽炎动物模型特征,乙酸乙酯部位提取物可显著改善急性咽炎大鼠的咽部病理形态学表现。不同剂量治疗组大鼠血清及咽部组织中IL-1β、IL-6及TNF-α炎性因子数量均下降,高剂量组下降最为明显。荔枝草乙酸乙酯提取物可明显增加大鼠咽部组织IκBα蛋白表达,降低NF-κBp65蛋白表达。结论 荔枝草乙酸乙酯部位提取物对急性咽炎具有治疗作用,可能与抑制咽部炎症病理改变的发生,能调节血液中炎症因子、抑制NF-κB表达和IκBα解离有关。 相似文献
4.
Curcumin Encapsulated into Biocompatible Co-Polymer PLGA Nanoparticle Enhanced Anti-Gastric Cancer and Anti-Helicobacter Pylori Effect 下载免费PDF全文
Jawed AlamFahima DilnawazSanjeeb Kumar SahooDurg Vijai Singh Asish Kumar MukhopadhyayTahziba HussainSanghamitra Pati 《Asian Pacific journal of cancer prevention》2022,23(1):61-70
Background: The current disadvantages (high cost, toxicity, resistance) of chemotherapy for gastric cancer opted people for alternative therapy from natural source. Curcumin (natural product) possess multiple biological activities but low bio-availability limits their uses as therapeutic. The Nano-formulation of curcumin increased the bioavailability and productivity of anti-cancer and anti-bacterial properties. The present study was initiated to determine the anti-cancer and anti-bacterial effect of Nano curcumin against gastric cancer and H. pylori. Methods: Curcumin loaded PLGA nanoparticles (CUR-NPs) was prepared by single emulsion solvent evaporation method. The MIC were determined using agar dilution method to find the anti-H. Pylori activity of Nano curcumin. The cytotoxicity of Nano curcumin was evaluated by MTT assay and the apoptotic effect (cell cycle arrest and morphology change) was shown by PI staining and microscopy. Results: The MIC of nanocurcumin and curcumin for all four H. pylori strains were 8 µg/ml and 16 µg/ml respectively. The inhibition rate of gastric cancer cells after treatment with curcumin was increased from 6% to 67% for 24h, from 8% to 75% for 48h, from 10% to 83% for 72h. In case of nanocurcumin, the inhibition rate increased from 7% to 69% for 24h, 11% to 87% for 48h and 16% to 97% for 72h. The IC50 of curcumin and Nano-curcumin were 24.20 µM and 18.78 µM respectively for 72 h. The population of cells in sub-G0 population increased from 4.1% in the control group to 24.5% and 57.8% when treated with curcumin and nanocurcumin respectively. After 72h of treatment with nanocurcumin, the apoptotic cells population increased as compared to native curcumin treated cells. Conclusion: The Nano curcumin might be used as a potential therapeutics against gastric cancer and H. Pylori. There is need of further in vivo study in order to validate CUR-NPs activity. 相似文献
5.
《Pediatric Dental Journal》2022,32(2):87-93
ObjectivesThe study aimed to estimate the age of Iraqi children and young adults based on the third molar development to establish Iraqi reference material for orthodontic and forensic purposes, and to investigate the correlation between the estimated and chronological age.MethodsA retrospective analysis of digital orthopantographs of 1515 patients of Iraqi origin, aged from 6 to 25 years was conducted, and the developmental status of the mandibular right third molar for each patient was evaluated using Demirjian et al.’s method. Statistical analysis was carried out using “Mann-Whitney U-test” between genders. The linear regression analysis was performed to obtain “regression formulas” for dental age calculation with chronologic age.ResultsNo statistically significant differences were observed between Iraqi males and females at any age. The median of male and female age of initial calcification of the cuspal tips for mandibular third molars was 9 years, whereas 14 years was the median of age for both genders when the crown was completed. All mandibular right third molars have a complete root formation with apex closure at a median of male and female age 22 years.ConclusionsThe use of Demirjian et al.’s method was appropriate as a reliable age indicator for Iraqi population. A strong correlation was observed between these stages and chronological age. Consequently, reference data have been established for mandibular third molar development in Iraqi population. 相似文献
6.
目的 基于红外热成像技术探讨“扶正温阳法”对阳虚质的影响,探讨阳虚质者红外热图的共性规律,分析判断“扶正温阳法”干预阳虚质人群的疗效。方法 纳入30例阳虚质患者给予益气温阳药物在大椎、肾俞(双侧)、命门等进行穴位贴敷,分别在干预前后运用红外热成像技术测定督脉、腰部、腹部、双手及双足局部温度的变化。结果 干预后阳虚体质患者的督脉、腰部、腹部、双手、双足温度均升高(P<0.05),阳虚体质局部温度得以改善。结论 本研究发现“扶正温阳法”可诱发循经热传导现象,通过调节热能代谢而起到调治阳虚体质的作用,红外热成像技术可用来辅助评价阳虚质的治疗效果,对临床指导制定阳虚质人群的干预方案疗效判定具有指导意义。 相似文献
7.
Eulerian Algorithms for Computing the Forward Finite Time Lyapunov Exponent Without Finite Difference upon the Flow Map 下载免费PDF全文
Guoqiao You Changfeng Xue & Shaozhong Deng 《Communications In Computational Physics》2022,31(5):1467-1488
In this paper, effective Eulerian algorithms are introduced for the computation of the forward finite time Lyapunov exponent (FTLE) of smooth flow fields. The
advantages of the proposed algorithms mainly manifest in two aspects. First, previous
Eulerian approaches for computing the FTLE field are improved so that the Jacobian
of the flow map can be obtained by directly solving a corresponding system of partial
differential equations, rather than by implementing certain finite difference upon the
flow map, which can significantly improve the accuracy of the numerical solution especially near the FTLE ridges. Second, in the proposed algorithms, all computations
are done on the fly, that is, all required partial differential equations are solved forward in time, which is practically more natural. The new algorithms still maintain the
optimal computational complexity as well as the second order accuracy. Numerical
examples demonstrate the effectiveness of the proposed algorithms. 相似文献
8.
以“七麦数据”网站收录的中医移动医疗App作为研究对象,采用网络调查法和文献分析法,根据“七麦数据”对移动医疗App的分类,结合中医移动医疗App的信息服务内容和特点,将筛选出的中医移动医疗App划分为医疗健康类、中医养生类、知识传播类、全面综合类,并根据“七麦数据”网站中对各类中医移动医疗App的打分及累计下载量筛选出最具代表性的12款中医移动医疗App,从全面性、人性化、安全性、实用性4个一级指标和40个二级指标对其信息服务现状进行评价,指出当前中医移动医疗App信息服务存在的问题并提出建议。 相似文献
9.
High Order Finite Difference Hermite WENO Fixed-Point Fast Sweeping Method for Static Hamilton-Jacobi Equations 下载免费PDF全文
In this paper, we combine the nonlinear HWENO reconstruction in [43] and
the fixed-point iteration with Gauss-Seidel fast sweeping strategy, to solve the static
Hamilton-Jacobi equations in a novel HWENO framework recently developed in [22].
The proposed HWENO frameworks enjoys several advantages. First, compared with
the traditional HWENO framework, the proposed methods do not need to introduce
additional auxiliary equations to update the derivatives of the unknown function $\phi$.
They are now computed from the current value of $\phi$ and the previous spatial derivatives of $\phi$. This approach saves the computational storage and CPU time, which greatly
improves the computational efficiency of the traditional HWENO scheme. In addition,
compared with the traditional WENO method, reconstruction stencil of the HWENO
methods becomes more compact, their boundary treatment is simpler, and the numerical errors are smaller on the same mesh. Second, the fixed-point fast sweeping method
is used to update the numerical approximation. It is an explicit method and does
not involve the inverse operation of nonlinear Hamiltonian, therefore any Hamilton-Jacobi equations with complex Hamiltonian can be solved easily. It also resolves some
known issues, including that the iterative number is very sensitive to the parameter $ε$ used in the nonlinear weights, as observed in previous studies. Finally, to further
reduce the computational cost, a hybrid strategy is also presented. Extensive numerical experiments are performed on two-dimensional problems, which demonstrate the
good performance of the proposed fixed-point fast sweeping HWENO methods. 相似文献
10.