全文获取类型
收费全文 | 43951篇 |
免费 | 2582篇 |
国内免费 | 245篇 |
专业分类
耳鼻咽喉 | 540篇 |
儿科学 | 1295篇 |
妇产科学 | 1099篇 |
基础医学 | 4556篇 |
口腔科学 | 1450篇 |
临床医学 | 3836篇 |
内科学 | 9418篇 |
皮肤病学 | 822篇 |
神经病学 | 2634篇 |
特种医学 | 1603篇 |
外国民族医学 | 5篇 |
外科学 | 7841篇 |
综合类 | 970篇 |
现状与发展 | 3篇 |
一般理论 | 31篇 |
预防医学 | 2939篇 |
眼科学 | 1677篇 |
药学 | 3465篇 |
1篇 | |
中国医学 | 328篇 |
肿瘤学 | 2265篇 |
出版年
2024年 | 48篇 |
2023年 | 504篇 |
2022年 | 1216篇 |
2021年 | 1978篇 |
2020年 | 1196篇 |
2019年 | 1519篇 |
2018年 | 1914篇 |
2017年 | 1375篇 |
2016年 | 1518篇 |
2015年 | 1615篇 |
2014年 | 2074篇 |
2013年 | 2532篇 |
2012年 | 3773篇 |
2011年 | 3663篇 |
2010年 | 2056篇 |
2009年 | 1727篇 |
2008年 | 2657篇 |
2007年 | 2693篇 |
2006年 | 2329篇 |
2005年 | 2050篇 |
2004年 | 1820篇 |
2003年 | 1557篇 |
2002年 | 1342篇 |
2001年 | 399篇 |
2000年 | 328篇 |
1999年 | 305篇 |
1998年 | 218篇 |
1997年 | 144篇 |
1996年 | 157篇 |
1995年 | 122篇 |
1994年 | 108篇 |
1993年 | 90篇 |
1992年 | 151篇 |
1991年 | 169篇 |
1990年 | 132篇 |
1989年 | 133篇 |
1988年 | 115篇 |
1987年 | 101篇 |
1986年 | 90篇 |
1985年 | 121篇 |
1984年 | 82篇 |
1983年 | 53篇 |
1982年 | 61篇 |
1981年 | 59篇 |
1980年 | 45篇 |
1979年 | 55篇 |
1978年 | 47篇 |
1976年 | 41篇 |
1975年 | 44篇 |
1974年 | 43篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Saima Ejaz Anwar Ali Kamran Azim Atif Mahmood Asif I. Khan Tuline A. Almazyad Bushra Bilal 《Saudi medical journal》2020,41(11):1234
Objectives:To investigate the relationship between a prostasin gene variations and the development of preeclampsia in a Pakistani female population.Methods:This was a case-control study carried out at University of Karachi, Karachi, Pakistan between May 2018 and 2019. A single nucleotide polymorphism (SNP) at rs12597511 locus was examined with polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analyses in 76 preeclamptic and 74 normotensive expecting mothers.Results:We observed significantly increased risk of preeclampsia associated with the CC genotype of rs12597511 polymorphism as compared to TT (p<0.001, OR=8.08, 95% CI:1.28-31.19) and TT/TC (p<0.001, OR=14.66 and 95% CI: 3.31-65.07) genotypes carriers. Calculation of the allelic distribution revealed a higher frequency of the T allele (82%) among controls; however, the C allele was more prevalent in the preeclamptic group (36%) significantly.Conclusion:The significantly higher C allele frequency in the prostasin gene at the rs12597511 locus in the preeclamptic group indicates that the distribution of the C allele of the prostasin gene is a potential risk factor contributing to the development of preeclampsia. 相似文献
992.
Mohamad-Hani A. Temsah Ayman A. Al-Eyadhy Fahad M. Al-Sohime Marwah M. Hassounah Mohammed A. Almazyad Gamal M. Hasan Amr A. Jamal Ali A. Alhaboob Majed A. Alabdulhafid Noura A. Abouammoh Khalid A. Alhasan Abdullah A. Alwohaibi Yousef T. Al Mana Abdullah T. Alturki 《Saudi medical journal》2020,41(11):1187
Objectives:To explore the changing patterns of long-stay patients (LSP) to improve the utilization of pediatric intensive care units (PICUs) resources.Methods:This is a 2-points cross-sectional study (5 years apart; 2014-2019) conducted among PICUs and SCICUs in Riyadh, Saudi Arabia. Children who have stayed in PICU for more than 21 days were included.Results:Out of the 11 units approached, 10 (90%) agreed to participate. The prevalence of LSP in all these hospitals decreased from 32% (48/150) in 2014 to 23.4% (35/149) in 2019. The length of stay ranged from 22 days to 13.5 years. The majority of LSP had a neuromuscular or cardiac disease and were admitted with respiratory compromise. Ventilator-associated pneumonia was the most prevalent complication (37.5%). The most commonly used resources were mechanical ventilation (93.8%), antibiotics (60.4%), and blood-products transfusions (35.4%). The most common reason for the extended stay was medical reasons (51.1%), followed by a lack of family resources (26.5%) or lack of referral to long-term care facilities (22.4%).Conclusion:A long-stay is associated with significant critical care bed occupancy, complications, and utilization of resources that could be otherwise utilized as surge capacity for critical care services. Decreasing occupancy in this multicenter study deserves further engagement of the healthcare leaders and families to maximize the utilization of resources. 相似文献
993.
Abdulellah M. Almohaya Naif H. Alotaibi Muath A. Alotaibi Ali M. Somily 《Saudi medical journal》2020,41(2):183
Objectives:To identify pulmonary tuberculosis (PTB) delayed inpatient diagnosis duration and contributing factors in an academic center in Saudi Arabia (SA).Methods:Retrospective review of all culture-confirmed PTB cases between May 2015 and April 2019. The outcomes were the timing between admission and suspicion of PTB or isolation to either early group (within 24 hours of admission) and late group (24 hours after admission).Results:Forty-nine cases were included with a median age of 49 years; a third of them were above 65 years of age. Most patients were of Saudi nationality and male. Approximately 38% of the cases were in the delayed group, half of them were smear-positive, with an average delay of 5.5 days. This was significant with age above 65 years (odds ratio [OR]=8.93, 95% confidence interval [CI]=2.22-35.95) presence of non-respiratory symptoms (OR=5.6, 95% CI=1.56-19.98), malignancy (OR=13.38, 95% CI=1.46-122.71), chronic medical problems (OR=4.90, 95% CI=1.31-18.32), missed chest x-ray findings (OR= 48, 95% CI=8.63-266.88) or procalcitonin level above 0.5 ng/mL (OR=12, 95% CI=1.58-91.08).Conclusion:Physicians in SA need to have a low threshold for PTB consideration in elderly patients or those with a history of malignancy. A careful review of the initial chest x-ray might help to overcome missing cases of PTB. 相似文献
994.
Majed A. Alghamdi Rajab A. Alzahrani Hashem H. Alhashemi Arwa A. Obaid Ali G. Alghamdi Mohammed A. Aldokhi Amal M. Alghamdi Abdulaziz A. Alghamdi Ahmed S. Qanat Wasil A. Jastaniah Suliman M. Alghamdi 《Saudi medical journal》2020,41(3):261
Objectives:To assess the quality and quantity of Saudi publications in oncology over a 10-year period.Methods:A systematic PubMed search was conducted between January 2008 and December 2017 to retrieve all Saudi oncology publications. Data about the articles was collected. The level of evidence (LOE) was independently assessed by 2 authors. Two 5-year periods (2008-2012 and 2013-2017) were compared using the relevant parameters. Clinicaltrials.gov was also searched for all oncology trials registered in Saudi Arabia.Results:A total of 839 publications met our inclusion criteria. The most common type of research was case series, totaling 32% of all publications. Clinical trials formed less than 2% of the total. The LOE was I, II, III, and IV in 0.3%, 2.1%, 58.4%, and 39.3% of the included publications, respectively. The LOE was the same in the 2 periods. There were more publications in international journals (p=0.004), more international collaborations (p=0.001), and higher journal impact factors (p=0.037) in 2013-2017 than in 2008-2012. Only 76 registered clinical trials were found in the Clinicaltrials.gov registry.Conclusion:Despite an increase in the number of Saudi publications in the field of oncology over time, the LOE did not change. There were, however, some improvements in the international collaboration and journal impact factor, as well as an increase in the number of studies published in international journals. These observations call for a national strategy to improve oncology research in Saudi Arabia. 相似文献
995.
Objective
Compare the impact of two interventions, a web-based support and a folder support, for young persons who care for people who suffer from mental illness.Methods
This study was a randomized control trial, following the CONSORT statements, which compared the impact of two interventions. Primary outcome variable was stress, and secondary outcome variables were caring situation, general self-efficacy, well-being, health, and quality of life of young informal carers (N = 241). Data were collected in June 2010 to April 2011, with self-assessment questionnaires, comparing the two interventions and also to detect changes.Results
The stress levels were high in both groups at baseline, but decreased in the folder group. The folder group had improvement in their caring situation (also different from the web group), general self-efficacy, well-being, and quality of life. The web group showed increase in well-being.Conclusion
Young informal carers who take on the responsibility for people close to them; suffer consequences on their own health. They live in a life-situation characterized by high stress and low well-being. This signals a need for support.Practice implications
The non-significant differences show that each intervention can be effective, and that it depends upon the individual's preferences. This highlights the importance of adopting person-centered approach, in which young persons can themselves choose support strategy. 相似文献996.
Wei Wu Ahmat Ali Ruxangul Jamal Mihray Abdulla Tursunnisahan Bakri Tursun Abdiryim 《RSC advances》2019,9(60):34691
In this paper, poly(3,4-ethylenedioxythiophene)/graphitic carbon nitride (PEDOT/g-C3N4) composites were prepared by the bromine catalysed polymerization (BCP) method with varying weight ratios of monomer to g-C3N4. For comparison, solid-state polymerization (SSP) and metal oxidative polymerization (MOP) methods were also used for the synthesis of PEDOT/g-C3N4 composites. Electrochemical determination of heavy metal ions (Cd2+ and Pb2+) was carried out by differential pulse voltammetry (DPV) on composite-modified glass carbon electrodes (GCEs), which were prepared by different methods. The obtained composites were analysed by Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible absorption spectroscopy (UV-vis), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results showed that the bromine catalysed polymerization (BCP) method is an effective way to prepare the PEDOT/g-C3N4 composite, and the combination of PEDOT with g-C3N4 can improve the electrochemical activity of electrode materials. And, the composite from the BCP method modified electrode (PEDOT/10 wt% g-C3N4/GCE) exhibited the widest linear responses for Cd2+ and Pb2+, ranging from 0.06–12 μM and 0.04–11.6 μM with detection limits (S/N = 3) of 0.0014 μM and 0.00421 μM, respectively.The PEDOT/g-C3N4 composite prepared by a Br2-catalyzed polymerization method exhibited the widest linear electrochemical responses for Cd2+ and Pb2+. 相似文献
997.
Asif Naleem Ali Zaman Kai Low Matthew D. Tam 《Surgical and radiologic anatomy : SRA》2014,36(4):341-344
Purpose
Lower limb angioplasty is a common procedure. However, arterial lengths have not been well studied and there is no evidence base for the optimum catheter lengths required for the various applications of femoral or distal below-the-knee angioplasty. The industry standard catheter measures 80 cm.Method
Fifty CT angiograms were post-processed using vessel tracking and centreline analysis tools and lengths were measured from the ipsilateral first segment of the femoral artery (FSFA) (common femoral artery) to the contralateral FSFA and on to the second segment of the femoral artery (superficial femoral artery) and popliteal arteries down to the posterior tibial (PT) artery at the ankle. This allowed clinically meaningful lengths for ‘cross-over’ and ‘antegrade’ angioplasty to be calculated.Results
Mean cross-over length to the second segment of the femoral artery as it crossed the femoral cortex was 72.3 cm, and the mean cross-over length to the popliteal artery at the knee joint was 83.8 cm, and the length from the FSFA to the PT was 85.1 cm.Conclusion
Selection of a standard length catheter can result in a situation where the catheter is too short. Optimum catheter length for a particular task will reduce the need for catheter exchanges and use of multiple balloons and therefore reduce complications, procedure time, radiation dose and cost. 相似文献998.
Qandeel Rehman Aimal Daud Khan Adnan Daud Khan Muhammad Noman Haider Ali Abdul Rauf Muhammad Shakeel Ahmad 《RSC advances》2019,9(59):34207
Improving the photon absorption in thin-film solar cells with plasmonic nanoparticles is essential for the realization of extremely efficient cells with substantial cost reduction. Here, a comprehensive study of solar energy enhancement in a cadmium telluride (CdTe) thin-film solar cell based on the simple design of a square array of plasmonic titanium nanoparticles, has been reported. The excitation of localized plasmons in the metallic nanostructures together with the antireflection coating (ARC) significantly enhances the absorption of photons in the active CdTe layer. The proposed structure attained super absorption with a mean absorbance of more than 97.27% covering a wide range from visible to near-infrared (i.e., from 300 nm to 1200 nm), presenting a 90% absorption bandwidth over 900 nm, and the peak absorption is up to 99.9%. For qualitative analysis, the photocurrent density is also estimated for AM 1.5 solar illumination (global tilt), whose value reaches 40.36 mA cm−2, indicating the highest value reported to date. The impact of nanoparticle dimensions, various metal materials, shapes, and random arrangement of nanoparticles on optical absorption are discussed in detail. Moreover, the angle insensitivity is essentially validated by examining the absorption performance with oblique incidences and it is found that the solar cell keeps high absorption efficiency even when the incidence angle is greater than 0°. Therefore, these findings suggest that the proposed broadband structure has good prospect in attaining high power conversion efficiency while reducing the device cost.Improving the photon absorption in thin-film solar cells with plasmonic nanoparticles is essential for the realization of extremely efficient cells with substantial cost reduction. 相似文献
999.
Azizullah Azizullah Zia Ur Rehman Imran Ali Waheed Murad Noor Muhammad Waheed Ullah Donat-Peter Häder 《Parasitology research》2014,113(12):4321-4326
Dengue, a mosquito-borne viral infection, is one of the major public health concerns in the tropical and subtropical regions of the world. Approximately, 2.5 billion people across the world are at risk from dengue and 50 to 100 million new infections of dengue occur annually. There is yet no vaccine or medicine available against dengue, and treatment remains only supportive. Targeting its vector by a combination of biological and chemical approaches and management of breeding sites are currently the only existing approaches to control or eliminate dengue. Chlorophyll derivatives like chlorophyllin and pheophorbide have been reported as effective natural photosensitizers against larvae of several insects including flies. Chlorophyll derivatives were also reported effective against larval stages of freshwater snails as well as against certain parasites of fish. This article briefly discusses the possible application of chlorophyll derivatives in controlling dengue vectors and hence the disease itself. Chlorophyll derivatives can prove to be a good contributor in an integrated approach against dengue. 相似文献