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   7767篇
  免费   679篇
  国内免费   334篇
耳鼻咽喉   17篇
儿科学   39篇
妇产科学   9篇
基础医学   796篇
口腔科学   625篇
临床医学   730篇
内科学   740篇
皮肤病学   36篇
神经病学   281篇
特种医学   297篇
外国民族医学   1篇
外科学   529篇
综合类   766篇
现状与发展   1篇
预防医学   320篇
眼科学   158篇
药学   2751篇
中国医学   559篇
肿瘤学   125篇
  2024年   23篇
  2023年   107篇
  2022年   262篇
  2021年   410篇
  2020年   277篇
  2019年   290篇
  2018年   291篇
  2017年   287篇
  2016年   300篇
  2015年   308篇
  2014年   438篇
  2013年   647篇
  2012年   391篇
  2011年   466篇
  2010年   354篇
  2009年   352篇
  2008年   325篇
  2007年   332篇
  2006年   313篇
  2005年   268篇
  2004年   248篇
  2003年   247篇
  2002年   187篇
  2001年   187篇
  2000年   157篇
  1999年   156篇
  1998年   134篇
  1997年   123篇
  1996年   110篇
  1995年   99篇
  1994年   78篇
  1993年   82篇
  1992年   100篇
  1991年   68篇
  1990年   63篇
  1989年   42篇
  1988年   59篇
  1987年   26篇
  1986年   29篇
  1985年   46篇
  1984年   21篇
  1983年   21篇
  1982年   11篇
  1981年   15篇
  1980年   8篇
  1979年   4篇
  1978年   5篇
  1977年   3篇
  1976年   4篇
  1973年   3篇
排序方式: 共有8780条查询结果,搜索用时 15 毫秒
1.
BackgroundPassive and hybrid passive ankle foot orthoses (AFOs) are often prescribed in post stroke drop foot; however, the effects of these AFOs on balance related parameters in these patients seem unclear. Accordingly, the aim of current study was to evaluate the role of the newly designed hybrid passive and Posterior Leaf Spring (PLS) AFOs on balance related parameters including: self-reported balance confidence (ABC), Timed Up and Go Test (TUG) and Berg Balance Scale (BBS) in post stroke drop foot patients.MethodsFifteen post stroke drop foot patients were recruited in current study. Then, ABC, TUG and BBS were assessed with newly designed AFO and PLS AFO.ResultsThe results of this study were shown a significant improvement in ABC, TUG and BBS scores with the newly designed AFO than PLS AFO (p < 0.05).ConclusionThis study suggested that the newly designed AFO was improved the balance related parameters than PLS AFO.  相似文献   
2.
BackgroundAnteriorly-loaded walking is common in many occupations and may increase fall risk. Dynamic gait stability, defined by the Feasible Stability Region (FSR) theory, quantifies the kinematic relationship between the body’s center of mass (COM) and base of support (BOS). FSR-based dynamic gait stability has been used to evaluate the fall risk.Research questionHow does front load carriage affect dynamic gait stability, step length, and trunk angle among young adults during treadmill walking?MethodsIn this between-subject design study, 30 healthy young adults were evenly randomized into three load groups (0%, 10%, or 20% of body weight). Participants carried their assigned load while walking on a treadmill at a speed of 1.2 m/s. Body kinematics were collected during treadmill walking. Dynamic gait stability (the primary variable) was calculated for two gait events: touchdown and liftoff. Step length and trunk angle were measured as secondary variables. One-way analysis of variance was conducted to detect any group-related differences for all variables. Post-hoc analysis with Bonferroni correction was performed when main group differences were found.ResultsNo significant differences but medium to large effect sizes were found between groups for dynamic gait stability at touchdown (p = 0.194, η2 = 0.114) and liftoff (p = 0.122, η2 = 0.139). Trunk angle significantly increased (indicating backward lean) with the front load at touchdown (p < 0.001, η2 = 0.648) and liftoff (p < 0.001, η2 = 0.543). No significant between-group difference was found related to the step length (p = 0.344, η2 = 0.076).SignificanceCarrying a front load during walking significantly alters the trunk orientation and may change the COM-BOS kinematic relationship and, therefore, fall risk. The findings could inform the design of future studies focusing on the impact of anterior load carriage on fall risk during different locomotion.  相似文献   
3.
BackgroundRocker sole (RS) shoes have been linked to impaired postural control. However, which features of RS design affect balance is unclear.Research questionWhich RS design features affect standing balance and gait stability?MethodsThis study utilized an intervention and cross-over design. Twenty healthy young adults (10 males and 10 females) participated in this study. Standing balance and gait stability were measured using a single force platform and three-dimensional motion analysis system, respectively. The experimental conditions included the control shoe and five RS shoes in the combination of apex position (%) and apex angle (degree) for RS50-95, RS60-95, RS70-95, RS60-70, and RS60-110. The main outcome measures were the area surrounding the maximal rectangular amplitude, mean path length, average displacement of the center of pressure along the lateral and anterior/posterior directions, and maximal center of pressure excursion as the standing balance and lateral margin of stability as the gait stability. Statistical analyses were conducted using a two-way split-plot analysis of variance with repeated measures (with RS design as the within-subject factor and sex as the between-subject factor) and the Bonferroni post hoc test (α = .05).ResultsRegarding the mean path length, RS60-70 was significantly longer than the control shoe, and it showed a significantly increased lateral margin of stability. Thus, RS60-70 was shown to affect standing balance, limit of stability, and gait stability of the frontal plane during gait.SignificanceThese results suggest that the apex angle of the RS design feature affects standing balance and gait stability, and RS60-70 is detrimental to stability. Therefore, when RS with a small apex angle is prescribed, it is necessary to consider the patient’s balance ability.  相似文献   
4.
5.
Our aim was to evaluate the long-term skeletal stability of the mandible in 21 patients after orthognathic surgery with physiological positioning. The measurement points SNB, B point (X, Y), Pog (X, Y), and the angle of the ramus were measured on cephalometric photographs to assess skeletal stability preoperatively, immediately after operation, and one and two years postoperatively. In addition, we evaluated the clinical symptoms of disorders of the temporomandibular joint (TMJ). The analysis of the cephalometric photographs showed that SNB, B point X, and Pog X showed no significant differences among the postoperative time points. On the other hand, B point Y and Pog Y showed no significant differences throughout the study period. We compared the angle of the ramus before operation and two years postoperatively, and no significant difference was found. In addition, no cases showed any pathological symptoms of disorders of the TMJ two years postoperatively. The long-term stability after orthognathic surgery with physiological positioning was confirmed, and it seems to be a reliable orthognathic treatment in patients with mandibular prognathism.  相似文献   
6.
We evaluated RNA stability of Ebola virus in EDTA blood and urine samples collected from infected patients and stored in West Africa’s environmental conditions. In blood, RNA was stable for at least 18 days when initial cycle threshold values were <30, but in urine, RNA degradation occurred more quickly.  相似文献   
7.
Purpose: Spray-freeze drying (SFD) is a recently applied method to develop pharmaceutical powders. This study aimed to analyze the competence of Trehalose, Mannitol, Lactose, and Sorbitol instability and aerosolization of Immunoglobulin G (IgG) via SFD.

Methods: Induced soluble aggregates were quantified at 0 and 3?months, and 45?°C using size-exclusion chromatography. Conformation and thermogravimetric assessments were done by Fourier transform infrared spectroscopy and differential scanning calorimetry. Laser light scattering was performed to determine the particle sizes. Aerodynamic features were characterized by twin stage impinger and scanning electron microscopy.

Results: Although sugars/polyols preferably stabilized IgG following the process, storage stabilization was achieved in Trehalose, Trehalose-Lactose, Lactose, and Trehalose-Mannitol-based powders with soluble aggregates <5%. The conformation of antibody was preserved with β sheet content from 66.28% to 76.37%. Particle sizes ranged from 5.23 to 8.12?µm. Mannitol exhibited the best aerodynamic behavior, fine particle fraction (FPF: 70%) but high degree of protein aggregation during storage.

Conclusions: SFD could favorably stabilize antibody using Trehalose and its combination with Lactose and Mannitol, and also, Lactose alone. Sorbitol disturbed IgG powder recovery. Incorporation of other types of excipient is required for efficient respiratory delivery of IgG molecules.  相似文献   

8.
《The surgeon》2020,18(3):165-177
IntroductionThe liver is the most frequently damaged organ in blunt abdominal trauma. It is widely accepted that hemodynamically stable patients with low-grade liver trauma should be treated with non-operative management, however there is controversy surrounding its safety and efficacy in high-grade trauma. The purpose of this review is to investigate the role of non-operative management in patients with high-grade liver trauma.MethodsPubMed and reference lists of PubMed articles were searched to find studies that examined the efficacy of non-operative management in high-grade liver injury patients, and compare it to operative management. Non-operative management was considered successful if rescue surgery was avoided. Outcomes considered were success, mortality, and complication rates.ResultsThe electronic search revealed 2662 records, 8 of which met the inclusion criteria. All 8 studies contained results suggesting that non-operative management was safe and effective in hemodynamically stable patients with high-grade liver trauma. By combining the outcomes of the different studies, non-operative management had a high success rate of 92.4% (194/210) in high-grade liver trauma patients, which was near the overall 95.0% non-operative management success rate. Non-operative management also had mortality and complication rates of 4.6% (9/194) and 9.7% (7/72) in high-grade injury patients, respectively, compared to operative management's 17.6% (26/148) and 45.5% (5/11).ConclusionNon-operative management of liver trauma is safe and effective in hemodynamically stable patients with high-grade liver injury. It is associated with significantly lower mortality compared with operative management. More studies are required to evaluate complications of non-operative management in high-grade liver injury.  相似文献   
9.
PURPOSE: The purpose of this study was to measure spectrophotometrically the color stability of pigmented A-2186 silicone maxillofacial elastomer with 10% by volume of titanium white dry earth opacifier before and after exposure to microwave energy over a simulated 1.5-year period of microwave sterilization. Materials AND METHODS: A-2186 silicone elastomer opacified with titanium white dry earth pigment, pigmented with 5 cosmetic dry earth pigment colors [no pigment (control) group (Pc), red (Pr), yellow ochre (Py), burnt sienna (Po), and a mixture of Pr + Py + Po color group (P3)], was used in this study. Each of the 5 experimental groups consisted of 5 specimens. All specimens were placed in a 250 ml glass beaker filled with 150 ml of water (replenished for each microwave exposure). An exposure of 6 minutes was used 18 times (simulating 1.5 years of microwave sterilization with one 6 minute exposure monthly). Reflectance values were measured by spectrophotometer. Three- and two-way analyses of variance with repeated measures were performed for the color difference (DeltaE*) with the factors of group/color/months, and group/months, respectively. Means were compared by Tukey Honest Significant Difference (HSD) multiple range test calculated at the 0.05 level of significance using SPSS. RESULTS: The trained human eye can detect color changes (DeltaE*) greater than 1.0. Most DeltaE* values of the red pigment group at all intervals and the mixed pigment group at 15- and 18- month intervals increased significantly greater than 1.0 (p < 0.001) compared with the control group. Yellow and burnt sienna groups remained the most color stable over time with DeltaE* values below 0.35. CONCLUSIONS: Lack of color stability of red dry earth pigmented A-2186 silicone maxillofacial elastomers was clinically significant after 12-month exposure to microwave energy as compared with yellow, burnt sienna, and opacified A-2186 dry earth pigments.  相似文献   
10.
替硝唑葡萄糖注射液的稳定性研究   总被引:6,自引:0,他引:6  
采用反相HPLC法测定替硝唑葡萄糖注射液中替硝唑的含量,用加温加速实验研究该制剂的热稳定动力学。结果表明,替硝唑的热降解反应为一级动力学过程,在50、65、80、95℃时的降解速度常数分别为5.58×10-4、2.66×10-3、8.10×10-3、2.82×10-2d-1,为8.3年,半衰期为39.5年。  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