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   7829篇
  免费   819篇
  国内免费   476篇
耳鼻咽喉   31篇
儿科学   36篇
妇产科学   73篇
基础医学   1096篇
口腔科学   80篇
临床医学   1079篇
内科学   1448篇
皮肤病学   60篇
神经病学   430篇
特种医学   277篇
外国民族医学   15篇
外科学   851篇
综合类   924篇
现状与发展   4篇
预防医学   453篇
眼科学   68篇
药学   809篇
  35篇
中国医学   585篇
肿瘤学   770篇
  2024年   19篇
  2023年   155篇
  2022年   346篇
  2021年   637篇
  2020年   482篇
  2019年   423篇
  2018年   418篇
  2017年   360篇
  2016年   391篇
  2015年   568篇
  2014年   658篇
  2013年   624篇
  2012年   760篇
  2011年   786篇
  2010年   506篇
  2009年   405篇
  2008年   385篇
  2007年   349篇
  2006年   306篇
  2005年   326篇
  2004年   64篇
  2003年   58篇
  2002年   25篇
  2001年   17篇
  2000年   14篇
  1999年   9篇
  1998年   6篇
  1997年   5篇
  1996年   3篇
  1995年   4篇
  1994年   4篇
  1993年   2篇
  1992年   1篇
  1990年   1篇
  1988年   1篇
  1984年   1篇
  1983年   2篇
  1982年   2篇
  1964年   1篇
排序方式: 共有9124条查询结果,搜索用时 31 毫秒
121.
In early life, over-nutrition may increase the risk of insulin resistance in the adult stage. Adiponectin and its receptor may play a key role in this process. This study aimed to identify the effect of a high-fat (HF) maternal diet on metabolic parameters and muscle adiponectin signaling in young adult offspring. We found that offspring born to dams fed HF chow (HF; 31% of calories from fat) had elevated body and adipose tissue weight and higher serum glucose levels after glucose challenge at three weeks (W3) and eight weeks (W8) of age. Offspring exposed to a HF diet also had higher serum adiponectin levels at W3 compared to controls. However, adiponectin levels were significantly decreased compared to controls by W8. Adiponectin receptor 1?mRNA expression in skeletal muscle was decreased in the HF group at W3 and W8, and there was no difference between the two groups in adiponectin receptor 2 expression. Furthermore, glucose transporter 4?mRNA and protein expression was decreased in the skeletal muscle of the HF group at W3 and W8. Our results suggest that a HF maternal diet decreases adiponectin receptor 1 expression in the offspring, which could contribute to reduced sensitivity to adiponectin and to adverse nutritional programing outcomes.  相似文献   
122.
目的 探讨艾滋病合并肺结核的临床特点及治疗。方法 对24例艾滋病合并肺结核进行回顾性分析。结果 两病并发率由1998年的0.05%上升至2002年的0.73%。HIV感染途径为静脉吸毒(77.1%)及性途径(22.9%);临床表现有发热(91.7%),咳嗽(91.7%),咳痰(79.2%),明显消瘦(79.2%),淋巴结肿大(54.7%);胸部X线表现以继发性肺结核为主(66.7%);合并病毒性肝炎50%,痰菌阳性率41.7%,PPD试验阳性率16.7%,14例抗结核治疗(3HRZE/9HRE)治愈或完成疗程,抗结核药物不良反应发生率为79.2%。结论 艾滋病合并肺结核常发病急、症状重、PPD试验阳性率低、抗结核药物治疗不良反应多,应加强艾滋病高发区及高危人群肺结核患者并发艾滋病的警惕性。  相似文献   
123.
To guarantee the long-term stability of an orthopaedic implant, non-degradable surface coatings with the ability to selectively release bioactive drugs or ions are especially desirable. In this study, SrO–TiO2 composite coatings were deposited on the surface of Ti alloys, whose release behavior of bioactive Sr ions was modulated by the Sr configurations, either interstitial atoms in solid solution (TiySr2−2yO2) or strontium titanate (SrTiO3). A perfect linear relationship between the amount of the released Sr ions and the Sr content in the coating was observed. Among the SrO-doped TiO2 coatings, the 20% SrO–TiO2 coating where Sr existed in both forms of TiySr2−2yO2 and SrTiO3 not only promoted proliferation of bone cells but also enhanced their osteogenic differentiation, which was proved to be related to its Sr release behavior. However, overdosing with 30% SrO only resulted in one single Sr configuration (SrTiO3) and an inferior osteogenic function. This study suggests that Sr configurations of both interstitial atoms of the solid solution and SrTiO3 can realize the selective release of Sr, but they possibly have different effects on the biological functions and other properties including corrosion resistance.

Strontium configurations can modulate its release in the SrO–TiO2 coating system, thus being able to control the interfacial osteogenesis.  相似文献   
124.
Since metal organic frameworks (MOF) have exhibited fascinating potential in biomedical applications, it is worthwhile to construct a MOF-based multifunctional drug delivery system. In the present study, the anticancer drug doxorubicin (DOX) was loaded into zeolitic imidazolate framework-8 (ZIF-8) via a one-pot process. The formed DOX@ZIF-8 was then coated with polydopamine, successively chelated with Fe3+ and conjugated with hyaluronic acid (HA), finally resulting in a multifunctional ZIF-8 nanocarrier. The characterization results confirmed the successful formation of the hybrid nanocarrier. pH-responsive drug release of DOX was observed due to the innate pH-dependent stability of ZIF-8. Importantly, the flow cytometry and confocal laser scanning microscope results both verified the targeting ability of DOX@ZIF-HA toward prostate cancer PC-3 cells. The improved therapeutic efficacy of DOX@ZIF-HA when compared to the inhibited group was also demonstrated. Furthermore, the chelation of Fe3+ by PDA makes the prepared DOX@ZIF-HA a good contrast agent for magnetic resonance (MR) imaging. Hence, we hope the constructed ZIF-8 based multifunctional nanocarrier could be a candidate for cancer theranostics.

DOX-doped MOF nanoparticles were prepared via a one-pot reaction and successively anchored with Fe3+ and HA for simultaneous targeted drug delivery and MR imaging.  相似文献   
125.
With a high specific capacity (4200 mA h g−1), silicon based materials have become the most promising anode materials in lithium-ions batteries. However, the large volume expansion makes the capacity reduce rapidly. In this work, a periodic silicon/carbon (Si/C) multilayer thin film was synthesized by magnetron sputtering method on copper foil. The titanium (Ti) film (about 20 nm) as the transition layer was deposited on the copper foil prior to the deposition of the multilayer film. Superior electrochemical lithium storage performance was obtained by the multilayer thin film. The initial discharge and charge specific capacity of the Si (15 nm)/C (5 nm) multilayer film anode are 2640 mA h g−1 and 2560 mA h g−1 with an initial coulombic efficiency of ∼97%. The retention specific capacity is about 2300 mA h g−1 and there is ∼87% capacity retention after 200 cycles.

With a high specific capacity (4200 mA h g−1), silicon based materials have become the most promising anode materials in lithium-ions batteries.  相似文献   
126.
To solve the problem of contamination of hexavalent chromium (Cr(vi)), visible-light-driven graphene-based ternary metal chalcogenide nanosheets (rGO/SnIn4S8) were synthesized via a one-pot surfactant-assisted hydrothermal method for the photoreduction of Cr(vi). Characterizations demonstrated that SnIn4S8 nanosheets were uniformly distributed on the surface of rGO and the as-synthesized nanosheets exhibited excellent photocatalytic activity under visible light. In addition, the effects of pH, concentration of critic acid, holes and electron scavengers on the reduction of Cr(vi) were systematically investigated. It was found that 50 mg L−1 of Cr(vi) could be completely removed within 30 min at pH 2 when citric acid served as a hole scavenger. Kinetic studies showed that the photocatalytic reduction of Cr(vi) processes obeyed the pseudo first order model. Further study indicated that the Cr(iii) species was immediately adsorbed onto the surface of the rGO/SnIn4S8 nanosheets after photocatalytic reduction of Cr(vi). Additionally, recycling results suggested that rGO/SnIn4S8 nanosheets possessed high recycle ability and stability after repeated use (5 times). This effective and promising work might provide a new strategy for the photoreduction of Cr(vi) and complete removal of chromium from effluent through the novel photocatalyst rGO/SnIn4S8.

Fabrication of visible-light-responsive photocatalyst (rGO/SnIn4S8) for photoreduction of Cr(vi) and adsorption of Cr(iii).  相似文献   
127.
The pathophysiology of delayed cerebral vasospasm (CVS) after subarachnoid haemorrhage (SAH) is multifaceted and involves endothelial apoptosis and inflammation. Ethyl pyruvate (EP) could attenuate early brain injury following SAH via anti-inflammation and inhibition of the c-Jun N-terminal kinase (JNK) signalling pathway. However, the role of EP in the delayed CVS has yet to be determined. In this study, we examined the effect of EP on endothelial apoptosis and inflammation and explore possible signalling pathways. We found that EP could significantly attenuate the delayed CVS. Possible mechanisms include a decrease in the endothelial cell apoptosis of the basilar artery and alleviation of endothelial inflammation. The JNK signalling pathway may play an important role in the neuroprotective effects of EP on delayed CVS. The results suggest that EP may be a possible therapy for delayed CVS, and the JNK signalling pathway should be targeted for therapeutic purposes in the future.

The pathophysiology of delayed cerebral vasospasm (CVS) after subarachnoid haemorrhage (SAH) is multifaceted and involves endothelial apoptosis and inflammation.  相似文献   
128.
Background: Despite great effort to control tuberculosis (TB), low treatment adherence threatens the success of drug therapy, increases the risk of TB transmission, and leads to the development of drug resistance. The present study assessed anti-TB treatment adherence in sputum smear-positive TB patients and examined the risk factors for poor patient adherence to identify targets for intervention. Methods: We monitored and followed up TB patients who were diagnosed between July 2014 and June 2015 in Xinjiang, China. A total of 8289 sputum smear-positive TB patients were included in this study. All patients registered their information during the first hospital visit or with the Centers for Disease Control, had regular follow-up visits, and accepted the anti-TB treatment. Insufficient re-examination adherence was defined as undergoing fewer than the recommended three sputum smear examinations during the treatment course. Results: Among 8289 patients, 3827 men (84.4% of male patients) and 3220 women (85.7% of female patients) had good adherence during treatment follow-up. 1242 patients (15.0%) did not complete regular follow-up. 332 (4.0%) patients lost contact. An adjusted logistic regression model showed that ethnicity, household address, treatment classification, patient source, and the actual management were significantly associated with non-adherence. Conclusion: The Xinjiang TB epidemic situation remains grim. Smear-positive patients had a higher proportion of non-adherence, which increased treatment difficulties and the risk of death from TB. Relevant medical departments should strengthen their supervision and interventions during the TB treatment process to improve patient adherence to anti-TB treatment.

Background: Despite great effort to control tuberculosis (TB), low treatment adherence threatens the success of drug therapy, increases the risk of TB transmission, and leads to the development of drug resistance.  相似文献   
129.
The rejection behaviors of two different charged composite hollow fiber nanofiltration (NF) membranes for six pharmaceutical molecules, primidone, carbamazepine, sulfamethoxazole, atenolol, sulfadimidine and norfloxacin, were characterized in this study. The saturation adsorption behaviors of the different pharmaceutical molecules on each membrane surface were studied and found to be related to the molecular weight, charge and hydrophilicity of the pharmaceutical molecules. After the pharmaceutical molecules reached adsorption equilibrium, the rejection rates of different NF membranes were characterized. The rejection rates of primidone, carbamazepine, sulfamethoxazole, atenolol, sulfadimidine and norfloxacin by the PEI-NF membrane were 85.6%, 91.8%, 79.9%, 98.1%, 93.3%, and 97.1%, respectively. Meanwhile, the rejection rates of the pharmaceutical molecules by the PIP-NF membrane were 82.2%, 85.4%, 91.5%, 79.1%, 87% and 93.3%, respectively. The influence of feed concentration, operation pressure, temperature, pH and ionic strength on the rejection behaviors of the different charged NF membranes were also studied.

The rejection behaviors of two different charged composite hollow fiber nanofiltration (NF) membranes for six pharmaceutical molecules, primidone, carbamazepine, sulfamethoxazole, atenolol, sulfadimidine and norfloxacin, were characterized in this study.  相似文献   
130.

Purpose

Contrast-enhanced ultrasound (CEUS) can distinguish between central lung cancer and atelectatic lung tissue. The aim of this study was to explore the clinical value of CEUS for biopsy in patients with central lung cancer with obstructive atelectasis.

Methods

One hundred and twelve patients were selected and CEUS was performed to display central lung cancer and atelectatic lung tissue. The front edge of central lung cancer was punctured with a needle, avoiding the necrotic area, under the guidance of CEUS.

Results

All of the 112 lesions were diagnosed with a clear central lung cancer mass and atelectatic lung tissue. In 104 cases, the central lung cancer mass presented with a “slow-in and fast-out” pattern compared to atelectatic lung tissue. In eight cases, the central lung cancer mass presented with a “fast-in and fast-out” pattern compared to atelectatic lung tissue. The mean number of punctures was 2.6, and the success rate of puncture biopsy was 98%. Of the 112 patients, six cases had hemoptysis during the procedure and 10 patients had bloody sputum in the postoperative period. No complications were found in the other cases.

Conclusion

CEUS has important clinical value for needle biopsy of central lung cancer with atelectasis.
  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