首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   4035篇
  免费   77篇
  国内免费   39篇
耳鼻咽喉   4篇
儿科学   54篇
妇产科学   80篇
基础医学   622篇
口腔科学   71篇
临床医学   433篇
内科学   412篇
皮肤病学   41篇
神经病学   136篇
特种医学   126篇
外科学   286篇
综合类   66篇
预防医学   735篇
眼科学   33篇
药学   802篇
中国医学   137篇
肿瘤学   113篇
  2024年   2篇
  2023年   187篇
  2022年   132篇
  2021年   190篇
  2020年   299篇
  2019年   169篇
  2018年   105篇
  2017年   188篇
  2016年   227篇
  2015年   205篇
  2014年   315篇
  2013年   214篇
  2012年   158篇
  2011年   130篇
  2010年   141篇
  2009年   156篇
  2008年   61篇
  2007年   107篇
  2006年   100篇
  2005年   52篇
  2004年   74篇
  2003年   71篇
  2002年   82篇
  2001年   65篇
  2000年   54篇
  1999年   80篇
  1998年   89篇
  1997年   81篇
  1996年   92篇
  1995年   74篇
  1994年   48篇
  1993年   37篇
  1992年   22篇
  1991年   26篇
  1990年   35篇
  1989年   21篇
  1988年   46篇
  1987年   9篇
  1984年   2篇
  1983年   1篇
  1980年   1篇
  1979年   2篇
  1974年   1篇
排序方式: 共有4151条查询结果,搜索用时 15 毫秒
1.
For supersaturating formulations of BCS-II compounds, which by definition have high intestinal permeability, a closed USP apparatus does not provide the necessary absorptive conditions during dissolution. To address this, an artificial gut simulator (AGS) has been constructed consisting of a 2.5 mL donor compartment in which a hollow fiber-based absorption module is suspended. Drug from donor diffuses across the hollow fiber membrane to be absorbed by the continuously flowing intraluminal receiver fluid. The membrane surface area and intraluminal fluid flow rate are tuned to obtain the physiologically observed absorption rate constant for a weakly basic, poorly water-soluble model compound, ketoconazole (KTZ). Supersaturated solutions of KTZ were generated in the donor in pH 6.5 phosphate buffer by the pH-shift method in the absence (closed system, control) and presence (open system, biorelevant) of an optimally or suboptimally tuned absorption module. Drug concentrations in the donor and intraluminal fluids were determined by in-line UV spectroscopy. The presence of an absorptive sink reduced the supersaturated solution's crystallization propensity, more so in the case of the optimally tuned AGS. This study demonstrates the significance of simulating absorption of drug at a physiological rate during dissolution studies, especially to predict the performance of formulations of BCS-II drugs.  相似文献   
2.
Gold nanoparticles (Au NPs) hold great promise in food, industrial and biomedical applications due to their unique physicochemical properties. However, influences of the gastrointestinal tract (GIT), a likely route for Au NPs administration, on the physicochemical properties of Au NPs has been rarely evaluated. Here, we investigated the influence of GIT fluids on the physicochemical properties of Au NPs (5, 50, and 100?nm) and their implications on intestinal epithelial permeability in vitro. Au NPs aggregated in fasted gastric fluids and generated hydroxyl radicals in the presence of H2O2. Cell studies showed that GIT fluids incubation of Au NPs affected the cellular uptake of Au NPs but did not induce cytotoxicity or disturb the intestinal epithelial permeability.  相似文献   
3.
Context Withania somnifera (L.) Dunal is traditionally used for treating various ailments, but lacks scientific evaluation.

Objective This study evaluates Withania somnifera (WS) for its effect on platelet activity and inflammatory enzymes.

Materials and methods Aqueous and ethanolic (1:1) leaf extracts were subjected to in vitro indirect haemolytic activity using Naja naja venom, human platelet aggregation was quantified for lipid peroxidation using arachidonic acid (AA) as agonist and 5-lipoxygenase (5-LOX) levels were determined using standard spectrometric assays. Further, molecular docking was performed by the ligand fit method using molegro software package (Molegro ApS, Aarhus, Denmark).

Results The study found that aqueous and ethanol extracts have very negligible effect (15%) with an IC50 value of 13.8?mg/mL on PLA2 from Naja naja venom. Further, extracts of WS also had very little effect (18%) with an IC50 value of 16.6?mg/mL on malondialdehyde (MDA) formation. However, a 65% inhibition of 5-LOX with an IC50 value of 0.92?mg/mL was observed in 1:1 ethanol extracts. The same was evident from SAR model with the active ingredient withaferin A binding predominantly on Phe 77, Tyr 98, Arg 99, Asp 164, Leu 168, Ser 382, Arg 395, Tyr 396 and Tyr 614 with an atomic contact energy value of??128.96 compared to standard phenidone (?103.61). Thus, the current study validates the application of WS for inflammatory diseases.

Conclusion This study reveals the inhibitory potential of W. somnifera on inflammatory enzymes and platelet aggregation. Thus, WS can serve as a newer, safer and affordable medicine for inflammatory diseases.  相似文献   
4.
5.
ObjectivesTo assess consumption of dietary and herbal supplements (DHS) among patients in internal medicine departments and determine whether such use is documented in their medical files.Methods267 patients from three internal medicine departments of an academic medical center in Haifa, Israel were assessed prospectively with questionnaires about their DHS use in the month preceding hospitalization. DHS were categorized into vitamins & minerals, herbal supplements and others. Further data was then collected from patients' medical records on socio-demographic and medical characteristics, as well as documentation of DHS use.Results123 patients (50.6 %) used DHS on a daily basis. Most of them (53.7 %) were using more than one DHS. DHS use was more prevalent in older (OR = 1.02 [1.001–1.036], p = 0.034) and educated (OR = 0.482 [0.252-0.923], p = 0.028) patients. Vitamins & minerals were used mainly to enhance vitality and address laboratory abnormalities, whereas herbal supplements were used mainly for gastrointestinal problems (p < 0.001). DHS use was reported to the physicians by 42 % of the patients, mostly at the patients’ initiative [92 (82.1 %), p < 0.001)]. Vitamins and minerals were the most reported category of DHS (94 (57.3 %), p < 0.001). The use of DHS was reported to physicians for 112 DHS (41.8 %) but only 32 DHS (11.9 %) were documented in their medical files. The documentation of vitamins and minerals was significantly higher compared to herbal supplements documentation (29 (17.7 %) & 3 (2.9 %) respectively, P < 0.001).ConclusionsDHS are commonly used by patients hospitalized in the internal medicine departments. Many patients do not report such use to the physicians, and more strikingly, physicians do not document DHS use in patient medical files. This communication gap may have serious medico-legal ramifications due to DHS side effects and DHS interactions with other DHS and with conventional drugs.  相似文献   
6.
7.
8.
9.
10.
Background: Asthma is a heterogeneous disorder of the airways related to inflammation; it affects millions of people worldwide. Due to the side effects of inhaled corticosteroids, researchers focused on the therapeutic effects of compounds derived from natural products. Objective: To investigate the therapeutic benefits of Narirutin a valuable flavonoid in Citri Reticulatae Pericarpium for asthma. Methods: Narirutin was extracted using the enzyme-assisted method with the L9 (34) orthogonal array to optimize the temperatures, pH, and reaction time. The mechanism of action of Narirutin was investigated via ELISA, flow cytometry, and Western blot analysis in vivo. Results: Narirutin suppressed inflammatory cell infiltration in the lung tissue and decreased IgE and IgG1 levels in serum in vivo. It can also alleviate interleukin (IL)-4, IL-5, and interferon-γ concentrations in bronchoalveolar lavage fluid in mice. Moreover, it increased the ratio of CD4+/CD8+ T cells. Additionally, Narirutin significantly suppressed p-ERK1/2 and p-JNK expression in the MAPK signaling pathway. Conclusion: Narirutin affects the Th1/Th2 imbalance through the p-ERK and p-JNK suppression in the MAPK signaling pathway.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号