全文获取类型
收费全文 | 390879篇 |
免费 | 48500篇 |
国内免费 | 3302篇 |
专业分类
耳鼻咽喉 | 7519篇 |
儿科学 | 11663篇 |
妇产科学 | 6893篇 |
基础医学 | 35890篇 |
口腔科学 | 5981篇 |
临床医学 | 50377篇 |
内科学 | 97295篇 |
皮肤病学 | 10565篇 |
神经病学 | 37966篇 |
特种医学 | 14351篇 |
外国民族医学 | 12篇 |
外科学 | 76626篇 |
综合类 | 3719篇 |
现状与发展 | 72篇 |
一般理论 | 319篇 |
预防医学 | 27879篇 |
眼科学 | 9826篇 |
药学 | 17773篇 |
5篇 | |
中国医学 | 367篇 |
肿瘤学 | 27583篇 |
出版年
2023年 | 5665篇 |
2022年 | 3051篇 |
2021年 | 8185篇 |
2020年 | 8818篇 |
2019年 | 7242篇 |
2018年 | 12847篇 |
2017年 | 11290篇 |
2016年 | 12741篇 |
2015年 | 13662篇 |
2014年 | 23070篇 |
2013年 | 26383篇 |
2012年 | 23050篇 |
2011年 | 23939篇 |
2010年 | 20279篇 |
2009年 | 22710篇 |
2008年 | 22007篇 |
2007年 | 21172篇 |
2006年 | 23372篇 |
2005年 | 20716篇 |
2004年 | 19023篇 |
2003年 | 16891篇 |
2002年 | 16001篇 |
2001年 | 5709篇 |
2000年 | 4438篇 |
1999年 | 5292篇 |
1998年 | 6470篇 |
1997年 | 5764篇 |
1996年 | 5305篇 |
1995年 | 5062篇 |
1994年 | 3576篇 |
1993年 | 3052篇 |
1992年 | 2594篇 |
1991年 | 2501篇 |
1990年 | 2002篇 |
1989年 | 2104篇 |
1988年 | 1958篇 |
1987年 | 1764篇 |
1986年 | 1808篇 |
1985年 | 1657篇 |
1984年 | 1736篇 |
1983年 | 1624篇 |
1982年 | 1861篇 |
1981年 | 1702篇 |
1980年 | 1503篇 |
1979年 | 1008篇 |
1978年 | 1057篇 |
1977年 | 1030篇 |
1976年 | 820篇 |
1975年 | 747篇 |
1974年 | 693篇 |
排序方式: 共有10000条查询结果,搜索用时 343 毫秒
211.
To determine if impaired energy metabolism might contribute to some aspects of Alzheimer disease (AD), including the vulnerability of the CA1 region of the hippocampal formation and the altered cytoskeleton evident in neurofibrillary tangles, we examined the effects of metabolic poisons on neuronal damage and cytoskeletal disruption in the hippocampal formation. Intrahippocampal injection of 3-nitropropionic acid (3-NP) and malonic acid resulted in neuronal death, particularly in CA1. Cytoskeletal disruption included loss of dendritic MAP2, but sparing of axonal τ. MK-801 (a noncompetitive NMDA receptor antagonist) did not atenuate the lesions produced by intrahippocampal injection of malonate. MK-801, however, was effective against intrastriatal malonate. Acute systemic 3-NP resulted in neuronal damage and cytoskeletal disruption in the CA1 region of the hippocampal formation, including an extensive loss of MAP2 immuno-reactivity, but sparing of τ. The neuronal loss in CA1 was delayed as compared to striatum. Chronic intraventricular infusion of 3-NP produced a different pattern of neuronal damage. Loss of τ-1 immuno-reactivity was observed in CA3 and CA1 s. oriens, whereas MAP2 immunostaining was preserved. These results demonstrate that chronic and acute administration of metabolic inhibitors produce distinct patterns of neuronal damage and cytoskeletal disruption. The results further suggest a differential involvement of the NMDA receptor in malonate-induced neuronal damage in striatum as compared to the hippocampus. The pattern of neuronal damage and cytoskeletal disruption observed following acute metabolic impairment resembled some aspects of neurofibrillary pathology in AD, but did not result in τ hyperphosphorylation. 相似文献
212.
Moshe Yaniv Tali Becker Michal Goldwirt Sam Khamis David M Steinberg Shlomo Weintroub 《Clinical journal of sport medicine》2006,16(5):392-396
OBJECTIVE: Little is known about the interactions of sports-related demands and human body, in particular on musculoskeletal features, during growth. Focusing on the relationship between soccer and lower limb alignment, we examined the hypothesis that varus knee deviation is more prevalent among high-performance pediatric and adolescent soccer players. DESIGN: Cross-sectional study with focused sampling. SETTING: First league sports clubs. PARTICIPANTS: 106 male child/adolescent soccer players aged 10 to 21 years and 68 age-matched tennis players. INTERVENTIONS: All athletes completed a demographic questionnaire and underwent physical examinations, which included height, weight, generalized laxity, knee, ankle, foot and spine axis, hip range of motion, tibial torsion, Q angle, foot navicular height, and progression angle. MAIN OUTCOME MEASUREMENT: Varus/valgus axis was determined by the intercondylar intermalleolar distance while standing. Soccer and tennis players were compared on knee axis and other outcome variables by analysis of covariance, adjusting for age and by t-tests within age groups. RESULTS: A significantly higher prevalence of knee varus was found among the soccer players compared to that among the tennis players. The difference in intracondylar distance was statistically significant after the age of 13 years (P < 0.001). In addition, compared to tennis players, soccer players had higher foot arches, decreased hip external rotation and increased external tibial torsion. CONCLUSIONS: Varus knee axis deviation was more common among children and adolescent soccer players than among tennis players. The prevalence was more pronounced among players aged 13 years or older. Further research is needed to explore the rationale of this phenomenon. 相似文献
213.
214.
Thierry Patrice David Olivier Ludovic Bourre 《Journal of environmental pathology, toxicology and oncology》2006,25(1-2):467-485
Photodynamic therapy (PDT) is based on the selective light activation of an exogenously given drug to patients. PDT acts mainly on cell membranes either of neovascular endothelial cells or of cancer cells leading to cancer cell death. Six drugs are now marketed based on clinical assays in various indications, which showed a clear cost efficiency as compared to other classical procedures. PDT is easy to handle and can be performed in medical installations fitting the conditions of health care in developing countries. Its cost effectiveness could represent an appropriate solution to the increasing number of cancers of various origin. However despite all the clinical results now available, PDT development remains slow. The reasons for this situation include cost of development, intellectual property, and competition between pharmaceutical companies. 相似文献
215.
Bo Jørgensen MD ; Gitte Juel Friis PhD ; Finn Gottrup MD DMSci 《Wound repair and regeneration》2006,14(3):233-239
Wound pain is a serious problem for elderly patients suffering from chronic leg ulcers, and it may lead to reduced wound healing rates and reduced quality of life. Biatain-Ibu Non-adhesive (Coloplast A/S), a new pain-reducing moist wound healing dressing containing ibuprofen was tested for pain reduction, safety, and efficacy on 10+2 patients in a single-blinded crossover study against Biatain Non-adhesive (Coloplast A/S). Pain was measured with a Numeric Box Scale before, during, and after dressing change. Quality of life was measured using the World Health Organization-5 Well-Being Index. Dressing moist wound healing properties such as absorption capacity and leakage were tested together with assessment of wound exudate and blood plasma content of ibuprofen. Use of the Biatain-Ibu foam dressing correlated with a decrease in pain intensity scores from 7 in the run-in period to approximately 2.5 in the Biatain-Ibu treatment phase. Quality of life measures were improved which together with the reduced pain could contribute to faster wound healing. The moist wound healing properties of Biatain-Ibu were similar to that of the Biatain Non-adhesive and ulcer size was reduced by 24% during the treatment period. Neither side effects nor systemic plasma concentrations of ibuprofen were observed. These data indicate that Biatain-Ibu could reduce persistent and temporary wound pain, increase Quality of life, was found safe to use, and had excellent moist wound healing properties. 相似文献
216.
217.
218.
Marlene L Hauck Susan M LaRue William P Petros Jean M Poulson Daohai Yu Ivan Spasojevic Amy F Pruitt Allison Klein Beth Case Donald E Thrall David Needham Mark W Dewhirst 《Clinical cancer research》2006,12(13):4004-4010
PURPOSE: To determine the maximum tolerated dose, dose-limiting toxicities, and pharmacokinetic characteristics of doxorubicin encapsulated in a low temperature sensitive liposome (LTSL) when given concurrently with local hyperthermia to canine solid tumors. EXPERIMENTAL DESIGN: Privately owned dogs with solid tumors (carcinomas or sarcomas) were treated. The tumors did not involve bone and were located at sites amenable to local hyperthermia. LTSL-doxorubicin was given (0.7-1.0 mg/kg i.v.) over 30 minutes during local tumor hyperthermia in a standard phase I dose escalation study. Three treatments, given 3 weeks apart, were scheduled. Toxicity was monitored for an additional month. Pharmacokinetics were evaluated during the first treatment cycle. RESULTS: Twenty-one patients were enrolled: 18 with sarcomas and 3 with carcinomas. Grade 4 neutropenia and acute death secondary to liver failure, possibly drug related, were the dose-limiting toxicities. The maximum tolerated dose was 0.93 mg/kg. Other toxicities, with the possible exception of renal damage, were consistent with those observed following free doxorubicin administration. Of the 20 dogs that received > or = 2 doses of LTSL-doxorubicin, 12 had stable disease, and 6 had a partial response to treatment. Pharmacokinetic variables were more similar to those of free doxorubicin than the marketed liposomal product. Tumor drug concentrations at a dose of 1.0 mg/kg averaged 9.12 +/- 6.17 ng/mg tissue. CONCLUSION: LTSL-doxorubicin offers a novel approach to improving drug delivery to solid tumors. It was well tolerated and resulted in favorable response profiles in these patients. Additional evaluation in human patients is warranted. 相似文献
219.
Christopher M Jewell Melissa E Hays Yukishige Kondo Nicholas L Abbott David M Lynn 《Journal of controlled release》2006,112(1):129-138
The ability of two redox-active, ferrocene-containing cationic lipids [11-(ferrocenylundecyl)trimethylammonium bromide (FTMA) and bis(11-ferrocenylundecyl)dimethylammonium bromide (BFDMA)] to transfect mammalian cells was investigated. This study sought to determine the range of conditions over which these lipids were capable of transfecting cells and whether the oxidation state of the ferrocenyl groups in these materials could be used to influence the extent of transfection. Experiments conducted in the COS-7 cell line demonstrated that reduced and oxidized FTMA were substantially cytotoxic and did not transfect cells. Subsequent experiments conducted using BFDMA and reporter plasmids encoding enhanced green fluorescent protein (EGFP) and firefly luciferase demonstrated that BFDMA was able to transfect cells. However, the extent of transfection depended significantly upon both the concentration of BFDMA and the oxidation state of the lipid. Quantitative characterization of cytotoxicity and gene expression demonstrated that a window of concentration existed over which reduced BFDMA was non-cytotoxic and yielded high levels of transfection, but over which electrochemically oxidized BFDMA yielded very low (background) levels of transfection. Characterization of lipoplexes using dynamic light scattering demonstrated that reduced and oxidized BFDMA formed small aggregates (ca. 90 to 250nm) at concentrations of lipid ranging from 2 to 10 microM. Taken together, these results demonstrate that the oxidation state of BFDMA, which can be controlled electrochemically, can be used to control the extent of cell transfection. These results could form the basis of transfection procedures that exploit the redox behavior of ferrocene-containing lipids to achieve active spatial and temporal control over transfection using electrochemical methods. 相似文献
220.