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   33624篇
  免费   2107篇
  国内免费   203篇
耳鼻咽喉   321篇
儿科学   559篇
妇产科学   449篇
基础医学   4665篇
口腔科学   898篇
临床医学   3486篇
内科学   7146篇
皮肤病学   675篇
神经病学   3739篇
特种医学   1961篇
外科学   5338篇
综合类   184篇
一般理论   7篇
预防医学   1413篇
眼科学   702篇
药学   1962篇
  1篇
中国医学   69篇
肿瘤学   2359篇
  2024年   99篇
  2023年   290篇
  2022年   530篇
  2021年   911篇
  2020年   677篇
  2019年   816篇
  2018年   935篇
  2017年   804篇
  2016年   930篇
  2015年   1136篇
  2014年   1362篇
  2013年   1652篇
  2012年   2693篇
  2011年   2795篇
  2010年   1676篇
  2009年   1494篇
  2008年   2385篇
  2007年   2386篇
  2006年   2228篇
  2005年   2174篇
  2004年   1963篇
  2003年   1788篇
  2002年   1648篇
  2001年   289篇
  2000年   202篇
  1999年   263篇
  1998年   312篇
  1997年   232篇
  1996年   184篇
  1995年   158篇
  1994年   129篇
  1993年   122篇
  1992年   70篇
  1991年   57篇
  1990年   55篇
  1989年   41篇
  1988年   37篇
  1987年   29篇
  1986年   28篇
  1985年   25篇
  1984年   40篇
  1983年   26篇
  1982年   32篇
  1981年   27篇
  1980年   17篇
  1978年   12篇
  1977年   12篇
  1974年   9篇
  1931年   7篇
  1927年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
A new implant surface has been developed with the purpose of avoiding as much stress shielding as possible, and thus prolong the prosthesis lifespan. The aim of this study was to investigate the in vitro effect of this new ultra-high roughness and dense Titanium (Ti) surface (PG60, Ra = 74 microm) in comparison with medium (TI01, Ra = 18 microm) and high (TI60, Ra = 40 microm) roughness and open porous coatings; all the coatings were obtained by vacuum plasma spraying. MG63 osteoblast-like cells were seeded on the tested materials and polystyrene, as control, for 3 and 7 days. Cells proliferated on the material surfaces similarly to the control. Alkaline phosphatase activity had lower values for TI60 than TI01 (p < 0.0005) and PG60 (p < 0.005). Osteocalcin levels measured on TI60 were significantly (p < 0.0005) lower in comparison with TI01 and PG60 at 7 days. Procollagen-I synthesis reduced with increasing roughness and the lowest data was found for PG60. While at 3 days Transforming Growth Factor beta1 levels augmented with increasing roughness, at 7 days TI60, the high roughness surface, was significantly lower than PG60 (p < 0.005) and TI01 (p < 0.001). All tested materials showed significantly higher Interleukin-6 levels than those of polystyrene at both experimental times. Nitric Oxide activity on TI01 was significantly (p < 0.05) higher than on TI60 and polystyrene. In conclusion, the new ultra-high roughness and dense coating PG60 provided a good biological response, even though, at least in vitro, it behaved similarly to the coatings already used in orthopaedics.  相似文献   
102.
The content of dissolved oxygen was determined by four independent methods in a series of non-aqueous or heterogenous systems. The Lex-O2-Content Analyzer represents a fast and simple apparatus that employs a coulometric oxygen assay with Hersch cell detection. A comparison of the results with different methods demonstrates the reliability of the Lex-O2 in the determination of oxygen dissolved in heterogeneous or non-aqueous systems. Therefore, this apparatus can be recommended for the measurement of oxygen in oxygenator or perfusion fluids, as well as in blood substitutes or other oxygen transporting systems.  相似文献   
103.
Bundesgesundheitsblatt - Gesundheitsforschung - Gesundheitsschutz - Partizipation zu ermöglichen ist Teil des Auftrags der Offenen Kinder- und Jugendarbeit. Dazu gehört die Einbindung der...  相似文献   
104.
105.
International Urology and Nephrology - To assess the efficacy of prophylaxis for urinary tract infections (UTI) in a two-year follow-up in women with StroVac compared to a therapy with...  相似文献   
106.
High-risk combinations of recipient and graft characteristics are poorly defined for liver retransplantation (reLT) in the current era. We aimed to develop a risk model for survival after reLT using data from the European Liver Transplantation Registry, followed by internal and external validation. From 2006 to 2016, 85 067 liver transplants were recorded, including 5581 reLTs (6.6%). The final model included seven predictors of graft survival: recipient age, model for end-stage liver disease score, indication for reLT, recipient hospitalization, time between primary liver transplantation and reLT, donor age, and cold ischemia time. By assigning points to each variable in proportion to their hazard ratio, a simplified risk score was created ranging 0–10. Low-risk (0–3), medium-risk (4–5), and high-risk (6–10) groups were identified with significantly different 5-year survival rates ranging 56.9% (95% CI 52.8–60.7%), 46.3% (95% CI 41.1–51.4%), and 32.1% (95% CI 23.5–41.0%), respectively (< 0.001). External validation showed that the expected survival rates were closely aligned with the observed mortality probabilities. The Retransplantation Risk Score identifies high-risk combinations of recipient- and graft-related factors prognostic for long-term graft survival after reLT. This tool may serve as a guidance for clinical decision-making on liver acceptance for reLT.  相似文献   
107.
108.
Summary The hexachlorophene-induced cytotoxic brain oedema is used as experimental model of brain damage, suitable for testing cerebroprotective substances. It has clinical importance since many brain injuries are accompanied by an oedema. The primary target of the neurotoxin, hexachlorophene, is the neuronal cell membrane, but it also causes secondary effects including a disruption of myelin lamellae, increases in water and sodium content, decreases of potassium content, and vacuolation in the white matter. Rats received orally hexachlorophene 240 mg/kg a day for three weeks by liquid diet. The disruption of coordinative motor response, observed in a specially developed test, was used to characterise hexachlorophene-induced injuries in studies designed to evaluate the potential of cerebroprotective substances. Because of their membranotropic efficacy some nootropic substances with different modes of action were examined. The disturbance of coordinative motor response was restored significantly earlier than in spontaneous remission following administration of piracetam, pyritinol, methyl glucamine orotate, naftidrofuryl, and also under the influence of the calcium antagonists cinnarizine, flunarizine and nifedipine. These results support the therapeutic use of nootropic substances in the management of neurotoxic injuries and brain oedema.  相似文献   
109.
Purpose Intracytoplasmic injection (ICSI) with testicular sperm was performed in 16 couples. All men had ductal obstruction and failed previous attempts of epididymal sperm microaspiration.Methods Testis tissue was obtained by excisional biopsies and incubated in HEPES buffered EBSS medium over 24 h at 37C. Motile sperm (Grade 1 to 2) were recovered in 13 patients and fertilized a total of 62 oozytes. Four pregnancies were achieved.Results One healthy boy and two girls (twin pregnancy) were born.Conclusions The ongoing pregnancies revealed no fetal abnormalities on ultrasound scanning.Presented at the IXth World Congress on In Vitro Fertilization and Alternate Assisted Reproduction, April 3–7, 1995, Vienna, Austria.  相似文献   
110.
Survived traumatic brain injuries (TBI) are one of the most serious challenges to the patient's future life. Recent literature increasingly questions the long believed protective effects of functional cerebral plasticity in children. Although TBI in children and adolescents is frequent, they are less frequently admitted to rehabilitation centers as in-patients than adults. This emphasizes the role of out-patient treatment. The progressing study described here aims to achieve a contribution to a comprehensive approach in TBI-rehabilitation for youngsters. A two-stage multimethodal program, starting with stimulation in coma while the patient is on the intensive care unit, and neuropsychological therapy after regaining consciousness is to be evaluated in a controlled, prospective and randomized study. After including nearly 50 % of the planned sample (100 persons), some preliminary results can be mentioned with all applicable caution. The effectiveness of the applied therapy can be stated here with respect to the posttraumatic development of intellectual abilities in the 6- and 12 months follow ups. Moreover, in the control group development of psychopathological alterations was found to a considerable degree and also lower ratings in a quality of life questionnaire, compared to the experimental group. It is expected to prove these differences statistically, after the total sample has been included, and thus equal distributions have been achieved in all predictive variables.  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