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   17563篇
  免费   1318篇
  国内免费   749篇
耳鼻咽喉   93篇
儿科学   190篇
妇产科学   141篇
基础医学   2978篇
口腔科学   731篇
临床医学   1320篇
内科学   2547篇
皮肤病学   141篇
神经病学   1066篇
特种医学   392篇
外国民族医学   1篇
外科学   1280篇
综合类   1837篇
现状与发展   1篇
预防医学   1112篇
眼科学   215篇
药学   4121篇
中国医学   763篇
肿瘤学   701篇
  2024年   30篇
  2023年   181篇
  2022年   438篇
  2021年   646篇
  2020年   448篇
  2019年   434篇
  2018年   455篇
  2017年   483篇
  2016年   532篇
  2015年   581篇
  2014年   943篇
  2013年   1229篇
  2012年   868篇
  2011年   1040篇
  2010年   873篇
  2009年   936篇
  2008年   975篇
  2007年   894篇
  2006年   868篇
  2005年   777篇
  2004年   683篇
  2003年   565篇
  2002年   472篇
  2001年   435篇
  2000年   349篇
  1999年   364篇
  1998年   314篇
  1997年   308篇
  1996年   244篇
  1995年   258篇
  1994年   213篇
  1993年   214篇
  1992年   177篇
  1991年   157篇
  1990年   151篇
  1989年   125篇
  1988年   132篇
  1987年   89篇
  1986年   77篇
  1985年   130篇
  1984年   84篇
  1983年   59篇
  1982年   47篇
  1981年   58篇
  1980年   40篇
  1979年   45篇
  1978年   35篇
  1977年   42篇
  1976年   22篇
  1973年   26篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
12.
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   

13.
《Vaccine》2016,34(30):3500-3507
We describe the preclinical development of a dengue virus vaccine targeting the dengue virus serotype 2 (DENV2) envelope domain III (EDIII). This study provides proof-of-principle that a dengue EDIII protein scaffold/DNA vaccine can protect against dengue challenge. The dengue vaccine (EDIII-E2) is composed of both a protein particle and a DNA expression plasmid delivered simultaneously via intramuscular injection (protein) and gene gun (DNA) into rhesus macaques. The protein component can contain a maximum of 60 copies of EDIII presented on a multimeric scaffold of Geobacillus stearothermophilus E2 proteins. The DNA component is composed of the EDIII portion of the envelope gene cloned into an expression plasmid. The EDIII-E2 vaccine elicited robust antibody responses to DENV2, with neutralizing antibody responses detectable following the first boost and reaching titers of greater than 1:100,000 following the second and final boost. Vaccinated and naïve groups of macaques were challenged with DENV2. All vaccinated macaques were protected from detectable viremia by infectious assay, while naïve animals had detectable viremia for 2–7 days post-challenge. All naïve macaques had detectable viral RNA from day 2–10 post-challenge. In the EDIII-E2 group, three macaques were negative for viral RNA and three were found to have detectable viral RNA post challenge. Viremia onset was delayed and the duration was shortened relative to naïve controls. The presence of viral RNA post-challenge corresponded to a 10–30-fold boost in neutralization titers 28 days post challenge, whereas no boost was observed in the fully protected animals. Based on these results, we determine that pre-challenge 50% neutralization titers of >1:6000 correlated with sterilizing protection against DENV2 challenge in EDIII-E2 vaccinated macaques. Identification of the critical correlate of protection for the EDIII-E2 platform in the robust non-human primate model lays the groundwork for further development of a tetravalent EDIII-E2 dengue vaccine.  相似文献   
14.
《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   
15.
目的观察急性脑梗死患者血清CRP在发病中的作用及临床意义。方法采用免疫比浊法对60例急性脑梗死患者的血清CRP水平进行动态观察(病程第1.7及14天),并与45例健康人进行比较。结果急性脑梗死患者血清CRP从病程第1天即升高(P〈0.01),至第7天达高峰,以后降低;重型患者明显高于轻、中型患者。结论血清CRP可能在急性脑梗死的发生、发展中起一定作用,并与病情严重程度呈正相关。  相似文献   
16.
目的:检测子宫内膜异位症(内异症)患者血清中差异表达的蛋白。方法:采用表面增强激光解吸/离子化飞行时间质谱(SELDI—TOF—MS)技术,选用WCX2蛋白质芯片对50例内异症及48例对照组血清标本进行检测以筛选内异症血清中差异表达的蛋白。结果:在Mr 0~50000范围内,检测出106个蛋白峰。内异症患者血清中差异表达的蛋白峰有4个。将发现的差异蛋白峰在Swiss蛋白数据库中搜索,发现Mr 9280蛋白峰与玻璃粘连蛋白Vitronectin相符。Vitronectin属于整合素家族,在内异症的粘附、侵袭、血管形成过程中起重要作用。其他的蛋白峰没有发现与之相匹配的蛋白,提示可能为新的蛋白质。结论:内异症患者血清中存在差异表达的蛋白,其对内异症的早期诊断具有一定的临床意义。SELDI蛋白芯片技术是一种快速、简单易行、样本用量少、高通量、重复性好的分析方法,具有广阔的临床应用前景。  相似文献   
17.
焦福利 《海南医学》2002,13(7):17-18
目的 本研究的目的在了解C反应蛋白的 (CRP)测定对于小儿败血症的诊断价值。方法 连续选取2 0例白细胞总数不高的小儿败血症患者 ,作回顾性研究对象。比较其治疗前和治疗后 7~ 1 0d后疾病的痊愈或明显好转时CRP水平 ,并与体温、白细胞分类结果进行比较。结果 治疗后CRP水平 (0 57± 0 68μg/ml)显著低于治疗前水平 (5 90± 3 57μg/ml) ,P <0 0 0 1 ;治疗前CRP的阳性率为 1 0 0 % ,显著高于嗜中性粒细胞比率 >75 %的阳性率 (30 % )和体温高于 37 5℃的阳性率 (30 % ) ,P <0 0 0 5。结论 CRP可以作为一种反映细菌感染的敏感指标 ,有助于不典型小儿败血症的诊断和疗效观察。  相似文献   
18.
PTEN基因蛋白在胆囊癌组织中表达的研究   总被引:4,自引:0,他引:4  
目的 :探讨抑癌基因PTEN蛋白在胆囊癌组织中的表达情况及其临床病理意义。方法 :应用免疫组化对 2 8例胆囊腺癌 ,4例胆囊鳞癌及其相应癌旁组织中PTEN蛋白进行检测 ,并结合患者的临床病理资料进行分析。结果 :PTEN蛋白在 32例癌旁组织中全都呈阳性表达 ,而癌组织中PTEN阳性表达率仅 34.4 %。胆囊癌组织中PTEN蛋白阳性表达与患者性别、年龄及组织类型无明显相关性 ,但与组织分化程度明显相关。结论 :PTEN蛋白在胆囊癌组织中阳性表达率较低 ,说明该基因失活可能在胆囊癌发生发展中起重要作用。PTEN阳性表达对胆囊癌患者的预后有一定意义  相似文献   
19.
Hydroxylation is the predominant pathway of metabolism for sulfatroxazole in the body, accounting for 70 per cent of the dose. Fifteen per cent of the dose is acetylated unimodally and 10 per cent is excreted unchanged. The half-lives of sulfatroxazole and its metabolites 5-hydroxysulfatroxazole and N4-acetylsulfatroxazole are approximately 22 h after administration of sulfatroxazole. N4-acetylsulfatroxazole, taken as parent drug, is eliminated by renal excretion (92 per cent of the dose). The initial elimination half-life of N4-acetylsulfatroxazole is 4.5 h, which later increases to 70 h as the result of the acetylation-deacetylation equilibrium. Probenecid inhibits the renal excretion of the metabolites 5-hydroxy- and N4-acetylsulfatroxazole. Inhibition of the N4-acetyl metabolite favours the deacetylation, which results in an increase of the T 1/2 of sulfatroxazole from 20 to 30 h. The protein binding value of sulfatroxazole is 84 per cent, that of N4-acetylsulfatroxazole is 37 per cent. Sulfatroxazole is excreted renally by passive processes, while the metabolites are excreted by both passive and active processes.  相似文献   
20.
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   
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