全文获取类型
收费全文 | 9522篇 |
免费 | 571篇 |
国内免费 | 86篇 |
学科分类
医药卫生 | 10179篇 |
出版年
2024年 | 18篇 |
2023年 | 187篇 |
2022年 | 563篇 |
2021年 | 705篇 |
2020年 | 424篇 |
2019年 | 510篇 |
2018年 | 499篇 |
2017年 | 322篇 |
2016年 | 337篇 |
2015年 | 387篇 |
2014年 | 444篇 |
2013年 | 530篇 |
2012年 | 826篇 |
2011年 | 776篇 |
2010年 | 365篇 |
2009年 | 339篇 |
2008年 | 516篇 |
2007年 | 505篇 |
2006年 | 430篇 |
2005年 | 398篇 |
2004年 | 303篇 |
2003年 | 291篇 |
2002年 | 160篇 |
2001年 | 49篇 |
2000年 | 38篇 |
1999年 | 33篇 |
1998年 | 22篇 |
1997年 | 7篇 |
1996年 | 18篇 |
1995年 | 8篇 |
1994年 | 12篇 |
1993年 | 10篇 |
1992年 | 8篇 |
1991年 | 12篇 |
1990年 | 11篇 |
1989年 | 9篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 12篇 |
1984年 | 9篇 |
1982年 | 6篇 |
1981年 | 13篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 7篇 |
1977年 | 4篇 |
1973年 | 3篇 |
1972年 | 4篇 |
1969年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Purpose:To evaluate the role of tranexamic acid in controlling intra-operative and immediate post-operative bleeding during external dacryocystorhinostomy.Methods:This was a double-blinded randomized placebo-controlled trial. All patients diagnosed with primary acquired nasolacrimal duct obstruction presenting between June 2018 to December 2019 were included in the study. All patients in the study group received a single dose of 1 gm tranexamic acid injection intravenously 30 minutes before the surgery, whereas the patients from group B (placebo) received normal saline. The effect of the injection was measured in terms of duration of the surgery, surgical field grading, amount of total blood loss during the surgery, and the need for postoperative nasal packing.Results:A total of 96 patients were included, of whom 45 were males and 51 were females. The study group (Group A) included 51 patients (27 males and 24 females) and the control group (Group B) included 45 patients (18 males and 27 females). There were no statistically significant differences between the two groups in terms of the duration of surgery (48.43 ± 20.01 minutes vs. 53.38 ± 19.8 minutes, P = 0.228), view of the surgical field (P = 0.084), the amount of intraoperative blood loss (88.63 ± 69.34 mL vs. 88.89 ± 51.93 mL, P = 0.984) and requirement of postoperative nasal packing (54.9% vs 62.2%, P = 0.471).Conclusion:There seems to be little to justify the role of preoperative intravenous tranexamic acid injection in controlling intra-operative and immediate postoperative bleeding during external dacryocystorhinostomy. 相似文献
72.
73.
Noman Javid Saquib Jalil Rubina Munir Muhammad Zia-ur-Rehman Amna Sahar Sara Arshad Jamshed Iqbal 《RSC advances》2023,13(3):1701
Two series of new 2,1-benzothiazine derivatives have been synthesized by condensation of 4-hydrazono-1-methyl-3,4-dihydro-1H-benzo[c][1,2]thiazine 2,2-dioxide (5) with 2-chloroquinoline-3-carbaldehydes and acetylthiophenes to acquire new heteroaryl ethylidenes 7(a–f) and 9(a–k) in excellent yields. After characterization by FTIR, 1H NMR, 13C NMR and elemental analyses, the newly synthesized analogues were investigated against monoamine oxidase enzymes (MAO A and MAO B). The titled compounds exhibited activity in the lower micromolar range among which 9e was the most potent compound against MAO A with IC50 of 1.04 ± 0.01 μM whereas 9h proved to be the most potent derivative against MAO B with an IC50 value of 1.03 ± 0.17 μM. Furthermore, in vitro results were further endorsed by molecular docking studies to determine the interaction between the potent compounds and the enzyme active site. These newly synthesized compounds represent promising hits for the development of safer and potent lead molecules for therapeutic use against depression and other neurological diseases.Two series of new 2,1-benzothiazine-heteroaryl ethylidene derivatives 7(a–f) and 9(a–k) have been synthesized in excellent yields and tested against MAOs. 相似文献
74.
Attia Hamid Asma Zafar Sabahat Latif Liangcai Peng Yanting Wang Iram Liaqat Muhammad Sohail Afzal Ikram ul-Haq Muhammad Nauman Aftab 《RSC advances》2023,13(2):1434
A low temperature alkali (LTA) pretreatment method was used to treat wheat straw. In order to obtain good results, different factors like temperature, incubation time, NaOH concentration and solid to liquid ratio for the pretreatment process were optimized. Wheat straw is a potential biomass for the production of monomeric sugars. The objective of the current study was to observe the saccharification (%) of wheat straw with immobilized magnetic nanoparticles (MNPs). For this purpose, immobilized MNPs of purified β-xylanase enzyme was used for hydrolysis of pretreated wheat straw. Wheat straw was pretreated using the LTA method and analyzed by SEM analysis. After completion of the saccharification process, saccharification% was calculated by using a DNS method. Scanning electron micrographs revealed that the hemicellulose, cellulose and lignin were partially removed and changes in the cell wall structure of the wheat straw had caused it to become deformed, increasing the specific surface area, so more fibers of the wheat straw were exposed to the immobilized β-xylanase enzyme after alkali pretreatment. The maximum saccharification potential of wheat straw was about 20.61% obtained after pretreatment with optimized conditions of 6% NaOH, 1/10 S/L, 30 °C and 72 hours. Our results indicate the reusability of the β-xylanase enzyme immobilized magnetic nanoparticles and showed a 15% residual activity after the 11th cycle. HPLC analysis of the enzyme-hydrolyzed filtrate also revealed the presence of sugars like xylose, arabinose, xylobiose, xylotriose and xylotetrose. The time duration of the pretreatment has an important effect on thermal energy consumption for the low-temperature alkali method.A low temperature alkali (LTA) pretreatment method was used to treat wheat straw. 相似文献
75.
76.
Sameen Ahmed Ayesha Vajeeha Muhammad Idrees Abrar Hussain Rakhtasha Munir Gulshan Zaidi Khadija Zahid Rizwan Ahmed Zareen Fatima Shazia Rafique Niaz M. Achakzai 《Medicine》2023,102(2)
High-risk-human papillomavirus (HR-HPV)-induced cervical cancer is the second most common cause of death among females worldwide. HPV16 is the most prevalent HR-HPV infection worldwide. This study found the genotypic distribution of HR-HPV in the local population and investigated the sequence variations among the E6 and E7 oncogenes of the local HPV16 genotype to the E6 and E7 oncogenes of the foreign HPV16 genotypes and constructed a phylogenetic relationship based on nucleotide sequence comparison among the variants identified in our study along with previously reported isolates that were obtained from different regions of the world. The samples were collected from patients with cervical cancer. Genomic DNA was extracted, and HR-HPV genotypes were determined using real-time PCR. The HPV16 E6 and E7 genes were amplified and sequenced. A HPV16 phylogenetic tree was constructed using the maximum likelihood method with MEGA 7. HPV16 was the most prevalent human papillomavirus (HPV) type identified in the present study. HPV16 isolates belonged to the A1 sublineage of the European branch. Twenty-one nucleotide sequences were included in this analysis. The first, second, and third codon positions are also included. The final dataset included 776 positions. 相似文献
77.
78.
Hazreen Abdul Majid Ai Kah Ng Maznah Dahlui Shooka Mohammadi Mohd Nahar Azmi bin Mohamed Tin Tin Su Muhammad Yazid Jalaludin 《Nutrients》2022,14(13)
A healthy eating environment in the school setting is crucial to nurture the healthy eating pattern for youth. Thus, it helps to combat the obesity issue. However, the impact of healthy school environment on healthy eating habits among Asian adolescents is scarce and less clear. This clustered randomised-control study has two objectives. The first objective was to evaluate the changes in adolescents’ dietary intake after the interventions for all arms (control; healthy cooking training only; subsidization with healthy cooking training). The second objective was to compare the effect of subsidization with healthy cooking training and healthy cooking training only with the control arm on adolescents’ dietary intakes. This study consisted of 340 secondary school students aged 14 years in rural and urban Malaysia. A total of two arms of intervention and one arm of control were included. Intervention one focused on healthy cooking preparation for the canteen and convenience shop operators. Intervention two included subsidization for fruits and vegetables with a healthy cooking preparation training for the canteen and suggestions on providing healthy options to the convenience shop operators. The outcome measured was changes to dietary intake. It was measured using a three-day dietary history pre- and post-intervention. A paired-t test was used to evaluate the outcome of intervention programmes on dietary changes for all arms (control, intervention one and two). An ANCOVA test was used to investigate the effect of providing subsidization and healthy cooking preparation training to the canteen and convenience shop operators on adolescents’ dietary intakes as compared to the control arm. Overall, the reduction in energy and carbohydrates for all arms were observed. Interestingly, fat intake was significantly increased after the four-week intervention programme under healthy cooking intervention but not in the food subsidization group. When comparing between control, healthy cooking training only and subsidization with the healthy cooking training arm, there was no significant changes between arms. A robust intervention to include subsidization of healthy foods for intervention programmes at schools in a larger scale study is needed to confirm this finding. 相似文献
79.
The evaluation of the shear capacity of an FRP-strengthened reinforced-concrete beam is challenging due to the complex interaction between different contributions provided by the concrete, steel stirrup and FRP reinforcement. The shape of the beam and the FRP inclination can have paramount importance that is not often recognized by the models that are suggested by codes. The interaction among different resisting mechanisms has a significant effect on the shear capacity of beams, since it can cause a reduction in the efficiency of some resisting mechanisms. A comparative study of the performance in the shear resistance assessment provided by three models with six different effectiveness factors (R) is performed, considering different cross-section shapes, FRP wrapping schemes, inclination and anchorage systems. The results revealed that the cross-section shape, the FRP inclination and the efficiency of the FRP anchorages have a significant effect on the shear strength of beams. The analysis results show that the three models are able to provide an accurate average estimation of shear strength (but with a coefficient of variation up to 0.35) when FRP reinforcement orthogonal to the beam axis is considered, while a significant underestimation (up to 19%) affected the results for inclined FRP reinforcement. Moreover, all the models underestimated the resistance of beams with a T section. 相似文献
80.
Muhammad Irfan Irshad Ahmad Shazia Shukrullah Humaira Hussain Muhammad Atif Stanislaw Legutko Jana Petru Michal Hatala Muhammad Yasin Naz Saifur Rahman 《Materials》2022,15(13)
The development of cost-effective co-catalysts of high photocatalytic activity and recyclability is still a challenge in the energy transformation domain. In this study, 0D/2D Schottky heterojunctions, consisting of 0D ZnO and 2D Ti3C2, were successfully synthesized by the electrostatic self-assembling of ZnO nanoparticles on Ti3C2 nanosheets. In constructing these heterojunctions, Ti3C2 nanosheets acted as a co-catalyst for enhancing the transfer of excitons and their separation to support the photocatalytic response of ZnO. The as-prepared ZnO/Ti3C2 composites demonstrate an abbreviated charge transit channel, a huge interfacial contact area and the interfacial electrons’ transport potential. The extended optical response and large reactive area of the ZnO/Ti3C2 composite promoted the formation of excitons and reactive sites on the photocatalyst’s surface. The ZnO/Ti3C2 Schottky heterojunction showed significantly high photocatalytic activity for hydrogen production from a water–ethanol solution under the light illumination in the visible region. The hydrogen evolution overoptimized the ZnO/Ti3C2 composition with 30 wt.% of Ti3C2, which was eight times higher than the pristine ZnO. These findings can be helpful in developing 0D/2D heterojunction systems for photocatalytic applications by utilizing Ti3C2 as a low-cost co-catalyst. 相似文献