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   2428篇
  免费   119篇
  国内免费   12篇
耳鼻咽喉   16篇
儿科学   66篇
妇产科学   86篇
基础医学   262篇
口腔科学   31篇
临床医学   243篇
内科学   516篇
皮肤病学   39篇
神经病学   108篇
特种医学   49篇
外国民族医学   3篇
外科学   501篇
综合类   59篇
一般理论   6篇
预防医学   110篇
眼科学   102篇
药学   215篇
中国医学   18篇
肿瘤学   129篇
  2024年   2篇
  2023年   29篇
  2022年   92篇
  2021年   108篇
  2020年   68篇
  2019年   95篇
  2018年   113篇
  2017年   66篇
  2016年   70篇
  2015年   70篇
  2014年   130篇
  2013年   134篇
  2012年   199篇
  2011年   224篇
  2010年   133篇
  2009年   110篇
  2008年   147篇
  2007年   155篇
  2006年   115篇
  2005年   105篇
  2004年   103篇
  2003年   76篇
  2002年   68篇
  2001年   10篇
  2000年   19篇
  1999年   14篇
  1998年   10篇
  1997年   11篇
  1996年   6篇
  1995年   6篇
  1994年   6篇
  1993年   6篇
  1992年   7篇
  1991年   3篇
  1990年   2篇
  1989年   4篇
  1988年   4篇
  1987年   3篇
  1985年   2篇
  1984年   2篇
  1983年   7篇
  1982年   4篇
  1981年   2篇
  1979年   2篇
  1973年   4篇
  1972年   3篇
  1969年   1篇
  1962年   1篇
  1961年   1篇
  1960年   1篇
排序方式: 共有2559条查询结果,搜索用时 15 毫秒
91.

Introduction

Reconstruction of distal leg region remained a difficult task. Free flaps had long been considered as a gold standard for these regions. However, due to various limitations of the free flap, a local fasciocutaneous flap could be considered as a good alternative. In this study, the use of a distally based posterior tibial artery perforator flap had been evaluated in the coverage of defects around the ankle, heel, and lower third of a leg. The study also outlined the donor-site morbidity and the technical details of the surgical procedure.

Methods

In this prospective study, a total of 42 patients with distal lower leg defects were included. The defects were located on the lower third of the leg (n?=?23), ankle (n?=?11), and heel (n?=?8). Reconstruction was performed using distally pedicled posterior tibial artery perforator flaps. Patients were evaluated in terms of viability of the flap, functional gain, and donor-site morbidity. The technical details of the operative procedure have also been outlined.

Results

All the flaps survived well, with the exception of one patient, who experienced complete flap loss. Minor complications were, however, noted in four other patients: One patient developed superficial epidermolysis; one developed postoperative venous congestion, which subsided within 3 days by conservative means, and in two patients, partial loss of the skin graft occurred at the donor site but healed completely with dressing and antibiotics. The patients were followed up for an average period of 6 months, ranging from 1 to 13 months. Donor-site morbidity was minimal.

Conclusions

It was concluded that the distally based pedicled posterior tibial artery perforator flap was a reliable, easy, less time-consuming, and versatile procedure for covering the defects around the ankle, heel, and lower third a leg. Level of Evidence: Level IV, therapeutic study  相似文献   
92.
93.
The design of efficient nonprecious catalysts for the hydrogen evolution reaction (HER) or the oxygen evolution reaction (OER) is a necessary, but very challenging task to uplift the water-based economy. In this study, we developed a facile approach to produce porous carbon from the dehydration of sucrose and use it for the preparation of nanocomposites with cobalt oxide (Co3O4). The nanocomposites were studied by the powder X-ray diffraction and scanning electron microscopy techniques, and they exhibited the cubic phase of cobalt oxide and porous structure of carbon. The nanocomposites showed significant OER activity in alkaline media, and the current densities of 10 and 20 mA cm−2 could be obtained at 1.49 and 1.51 V versus reversible hydrogen electrode (RHE), respectively. The impedance study confirms favorable OER activity on the surface of the prepared nanocomposites. The nanocomposite is cost-effective and can be capitalized in various energy storage technologies.

The design of efficient nonprecious catalysts for the hydrogen evolution reaction (HER) or the oxygen evolution reaction (OER) is a necessary, but very challenging task to uplift the water-based economy.  相似文献   
94.
In this paper, we study double cascade dressed optical metal oxide semiconductor field-effect transistor (MOSFET) by exploiting enhancement and suppression for mixed-phase (hexagonal + tetragonal) of Eu3+:YPO4 and different phases (hexagonal + tetragonal and pure tetragonal) of Pr3+:YPO4 crystals. We report variation of fine structure energy levels in different doped ions (Eu3+ and Pr3+) in the host YPO crystal. We compared multi-level energy transition from a single dressing laser with single level energy transition from double cascade dressing lasers. Gate delay facilitates multi-energy level dressed transition and is modeled through a Hamiltonian. Based on the results of double cascade dressing, we have realized MOSFET for logic gates (inverter and logic not and gate) with a switching contrast of about 92% using a mixed phase of Pr3+:YPO4.

By changing different parameters of single and double lasers, we observed the dressed energy level transition from single to multi-level with a single laser. Each sample responded based on their ions'' structure and phase symmetry in the host YPO crystal.  相似文献   
95.
Information obtained on the Internet regarding medical procedures is largely unregulated and can be confusing. The aims of this study were to assess use of the Internet by patients attending hospital for oral and maxillofacial procedures, and to assess the quality of information provided at consultation. Data were collected prospectively using a confidential questionnaire, which was distributed to consecutive patients attending for elective operations at 2 oral and maxillofacial units: Crosshouse Hospital, Kilmarnock, and Queen Alexandra Hospital, Portsmouth (n = 100 at each unit). All the distributed questionnaires were returned. At both units, 95% of patients thought that discussion at the initial consultation was good or very good, and 84% at both units stated that they had access to the Internet. Internet access was consistently high among all age groups up to the age of 65, but in those aged over 65 it was considerably lower. A total of 22/84 patients (26%) at Crosshouse, and 14/84 (17%) at Queen Alexandra used the Internet to gain further information regarding their condition or procedure. All of those (n = 14) at Queen Alexandra, and 21/22 at Crosshouse had used Google to search for the information. Those who used the Internet to find information on their medical condition or procedure found it to be a useful resource, but they also stated that the information caused some concerns. With use of the Internet and access to it increasing we highlight the need for regulated and appropriate websites to which patients should be directed.  相似文献   
96.
Proceedings of the National Academy of Sciences, India Section B: Biological Sciences - Endophytic microbes residing inside the tissues of plants play a significant role to enhance the growth and...  相似文献   
97.
Apigenin is an edible plant‐derived flavonoid that has been reported as an anticancer agent in several experimental and biological studies. It exhibits cell growth arrest and apoptosis in different types of tumors such as breast, lung, liver, skin, blood, colon, prostate, pancreatic, cervical, oral, and stomach, by modulating several signaling pathways. Apigenin induces apoptosis by the activation of extrinsic caspase‐dependent pathway by upregulating the mRNA expressions of caspase‐3, caspase‐8, and TNF‐α. It induces intrinsic apoptosis pathway as evidenced by the induction of cytochrome c, Bax, and caspase‐3, while caspase‐8, TNF‐α, and B‐cell lymphoma 2 levels remained unchanged in human prostate cancer PC‐3 cells. Apigenin treatment leads to significant downregulation of matrix metallopeptidases‐2, ?9, Snail, and Slug, suppressing invasion. The expressions of NF‐κB p105/p50, PI3K, Akt, and the phosphorylation of p‐Akt decreases after treatment with apigenin. However, apigenin‐mediated treatment significantly reduces pluripotency marker Oct3/4 protein expression which might be associated with the downregulation of PI3K/Akt/NF‐κB signaling.  相似文献   
98.
ObjectivesDengue remains hyperendemic in Malaysia despite extensive vector control activities. With dynamic changes in land use, urbanisation and population movement, periodic updates on dengue transmission patterns are crucial to ensure the implementation of effective control strategies. We sought to assess shifts in the trends and spatial patterns of dengue in Kelantan, a north-eastern state of Malaysia (5°15’N 102°0’E).MethodsThis study incorporated data from the national dengue monitoring system (eDengue system). Confirmed dengue cases registered in Kelantan with disease onset between January 1, 2016 and December 31, 2018 were included in the study. Yearly changes in dengue incidence were mapped by using ArcGIS. Hotspot analysis was performed using Getis-Ord Gi to track changes in the trends of dengue spatial clustering.ResultsA total of 10 645 dengue cases were recorded in Kelantan between 2016 and 2018, with an average of 10 dengue cases reported daily (standard deviation, 11.02). Areas with persistently high dengue incidence were seen mainly in the coastal region for the 3-year period. However, the hotspots shifted over time with a gradual dispersion of hotspots to their adjacent districts.ConclusionsA notable shift in the spatial patterns of dengue was observed. We were able to glimpse the shift of dengue from an urban to peri-urban disease with the possible effect of a state-wide population movement that affects dengue transmission.  相似文献   
99.
100.
Transplant ureteric stent insertion reduces the incidence of MUCs, but it is not known whether routine PSRGU is needed to detect unmasked MUCs. This study evaluated whether routine PSRGU in the pRTR is a useful tool to identify MUCs before they become clinically apparent. A retrospective analysis was undertaken of the clinical outcomes following elective stent removal from pediatric kidney‐only transplant recipients at two London centers between 2012 and 2016. Our policy was to perform PSRGU either routinely or urgently if there were concerning symptoms or biochemical evidence of renal allograft dysfunction. Elective stent removal was performed in 86% (97 of 113 pRTR), and 75 (77%) of whom had routine PSRGU at a median (IQR) of 6 (2‐8) days after stent removal. There were changes to management in 3 (4%) of pRTR with PSRGU identifying no MUC. Nineteen patients (25%) had urgent PSRGU, most commonly due to renal allograft dysfunction, at a median (IQR) of 5.5 (2.7‐12.3) days after stent removal. Of these, two pRTR required ureteric intervention. For our current practice of removing transplant stents at 4‐6 weeks post‐transplantation, our study has found no evidence to support routine PSRGU after elective stent removal.  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