全文获取类型
收费全文 | 401702篇 |
免费 | 16150篇 |
国内免费 | 988篇 |
专业分类
耳鼻咽喉 | 3610篇 |
儿科学 | 12414篇 |
妇产科学 | 7307篇 |
基础医学 | 45038篇 |
口腔科学 | 5807篇 |
临床医学 | 35554篇 |
内科学 | 78813篇 |
皮肤病学 | 3843篇 |
神经病学 | 39240篇 |
特种医学 | 18499篇 |
外国民族医学 | 13篇 |
外科学 | 64375篇 |
综合类 | 4812篇 |
现状与发展 | 1篇 |
一般理论 | 177篇 |
预防医学 | 33865篇 |
眼科学 | 8133篇 |
药学 | 24527篇 |
1篇 | |
中国医学 | 941篇 |
肿瘤学 | 31870篇 |
出版年
2023年 | 1335篇 |
2022年 | 2189篇 |
2021年 | 5330篇 |
2020年 | 3045篇 |
2019年 | 5062篇 |
2018年 | 27071篇 |
2017年 | 21080篇 |
2016年 | 23545篇 |
2015年 | 6573篇 |
2014年 | 9074篇 |
2013年 | 11941篇 |
2012年 | 23870篇 |
2011年 | 38049篇 |
2010年 | 28114篇 |
2009年 | 20249篇 |
2008年 | 34416篇 |
2007年 | 37339篇 |
2006年 | 16628篇 |
2005年 | 18025篇 |
2004年 | 18280篇 |
2003年 | 17879篇 |
2002年 | 15485篇 |
2001年 | 2170篇 |
2000年 | 1803篇 |
1999年 | 2143篇 |
1998年 | 2965篇 |
1997年 | 2398篇 |
1996年 | 2002篇 |
1995年 | 1852篇 |
1994年 | 1614篇 |
1993年 | 1547篇 |
1992年 | 1011篇 |
1991年 | 1002篇 |
1990年 | 900篇 |
1989年 | 812篇 |
1988年 | 726篇 |
1987年 | 649篇 |
1986年 | 656篇 |
1985年 | 705篇 |
1984年 | 926篇 |
1983年 | 806篇 |
1982年 | 1057篇 |
1981年 | 964篇 |
1980年 | 874篇 |
1979年 | 466篇 |
1978年 | 522篇 |
1977年 | 449篇 |
1976年 | 427篇 |
1975年 | 319篇 |
1974年 | 328篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Evidence of Increased Class I MHC Expression on Human Peripheral Blood Lymphocytes during Acute Ethanol Intoxication 总被引:1,自引:0,他引:1
Michael A. Kolber PhD MD Ron M. Walls MD Marion L. Hinners MS Dinah S. Singer PhD 《Alcoholism, clinical and experimental research》1988,12(6):820-823
Certain ethanol-related diseases in humans have been linked to disorders of immunity. Although humoral and cellular immunity have been studied, the precise mechanisms whereby ethanol use leads to tissue damage remain unknown. In order to explore the hypothesis that ethanol may lead to alteration in expression of tissue Class I major histocompatibility antigen causing an autoimmune phenomenon, a population of acutely ethanol-intoxicated patients was studied. Measurement of Class I major histocompatibility antigen on peripheral blood lymphocytes in this population showed a highly significant (p less than 0.01) increase over controls. The role that this increased antigenicity may play in the evolution of clinical disease is discussed. 相似文献
992.
Michael J. Eckardt PhD Robert R. Rawlings MS Barry I. Graubard MA Vivian Faden PhD Peter R. Martin MD Louis A. Gottschalk MD PhD 《Alcoholism, clinical and experimental research》1988,12(1):88-93
Commonly used neuropsychological tests were administered to 91 detoxified alcoholics at the beginning of treatment. Statistically significant relationships were observed between test scores and post treatment consumption determined 8 months after completing treatment for 72 patients. The results varied depending upon the particular measure of posttreatment consumption evaluated and the type of statistical analysis used. The most consistent relationships were often counter to the notion that increased neuropsychological performance is correlated with a more favorable treatment outcome. Neuropsychological evaluation is of limited clinical utility in predicting posttreatment alcohol consumption. 相似文献
993.
Michael D Seidman Mumtaz J Khan Wen Xue Tang Wayne S Quirk 《Otolaryngology--head and neck surgery》2002,127(3):138-144
OBJECTIVES: Lecithin is a polyunsaturated phosphatidylcholine (PPC), which are high energy functional and structural elements of all biologic membranes. PPC play a rate-limiting role in the activation of numerous membrane-located enzymes, including superoxide dismutase and glutathione, which are important antioxidants protecting cell membranes from damage by reactive oxygen species (ROS). ROS-induced damage to mitochondrial DNA may lead to reduced mitochondrial function in the cochlea and resultant hearing loss. STUDY DESIGN AND SETTING: The effects of lecithin on aging and age-associated hearing loss were studied in rats by measuring hearing sensitivities using auditory brainstem responses (ABR). In addition, mitochondrial function as a measure of aging was assessed by determining mitochondrial membrane potentials using flow cytometry and by amplifying mitochondrial DNA deletions associated with aging. Harlan-Fischer rats aged 18 to 20 months (n = 14) were divided into 2 groups. The experimental group was supplemented orally for 6 months with lecithin, a purified extract of soybean phospholipid (Nutritional Therapeutics, Allendale, NJ). RESULTS: The data obtained were compared with the control group. ABRs were recorded at 2-month intervals and showed significant preservation of hearing sensitivities in the treated subjects. Flow cytometry revealed significantly higher mitochondrial membrane potentials in the treated subjects, suggesting preserved mitochondrial function. Finally, the common aging mitochondrial DNA deletion (mtDNA(4834)) were amplified from brain and cochlear tissue including stria vascularis and auditory nerve. This specific deletion was found significantly less frequent in all tissues in the treated group compared with the controls. CONCLUSION: These experiments support our hypothesis and provide evidence that lecithin may preserve cochlear mitochondrial function and protect hearing loss associated with aging. 相似文献
994.
Cortical spreading depression in the feline brain following sustained and transient stimuli studied using diffusion-weighted imaging 总被引:1,自引:0,他引:1
995.
Michael J. Lambert Jason L. Whipple David A. Vermeersch David W. Smart Eric J. Hawkins Stevan Lars Nielsen Melissa Goates 《Clinical psychology & psychotherapy》2002,9(2):91-103
Several systems have been developed to monitor and feedback information about a client's responses to psychotherapy as a method of enhancing client outcome. The current study divided 1020 clients into four groups (two experimental and two control) to determine if feedback regarding client progress, when provided to a therapist, affected client outcome and number of sessions attended. Results showed that feedback increased the duration of treatment and improved outcome for clients identified as potential treatment failures thereby replicating an earlier study using nearly identical methodology. Nearly twice as many clients in the feedback group achieved clinically significant or reliable change and fewer were classified as deteriorated by the time treatment ended. For those clients who were predicted to have a positive response to treatment, feedback to therapists resulted in an equal number of treatment sessions and equivalent outcomes compared to the no feedback controls. The results are discussed in terms of quality management in routine clinical practice and the need to base treatment decisions on clients' response to treatment rather than arbitrary session limits. Suggestions for additional research aimed at enhancing the effects of feedback on client outcome are made. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
996.
Genetic ablation of the t-SNARE SNAP-25 distinguishes mechanisms of neuroexocytosis. 总被引:12,自引:0,他引:12
Philip Washbourne Peter M Thompson Mario Carta Edmar T Costa James R Mathews Guillermina Lopez-Benditó Zoltán Molnár Mark W Becher C Fernando Valenzuela L Donald Partridge Michael C Wilson 《Nature neuroscience》2002,5(1):19-26
Axon outgrowth during development and neurotransmitter release depends on exocytotic mechanisms, although what protein machinery is common to or differentiates these processes remains unclear. Here we show that the neural t-SNARE (target-membrane-associated-soluble N-ethylmaleimide fusion protein attachment protein (SNAP) receptor) SNAP-25 is not required for nerve growth or stimulus-independent neurotransmitter release, but is essential for evoked synaptic transmission at neuromuscular junctions and central synapses. These results demonstrate that the development of neurotransmission requires the recruitment of a specialized SNARE core complex to meet the demands of regulated exocytosis. 相似文献
997.
998.
999.
The popularization and application of cold storage red blood cells or whole blood at −80 °C of the Rh(D) negative patients in surgical operation 总被引:2,自引:0,他引:2
Summary The efficiency of cold storage red blood cells (CSRBC) or whole blood at −80 °C used in 27 Rh(D) negative patients during
surgical operation was reported. The Rh(D) negative patients received the transfusion of CSRBC or whole blood stored at −80
°C for 180 to 360 days. The changes in the indexes, such as blood TB, DB, K+, Na+, BUN, Cr, urine protein (URPO), UOB, Hb, HCT, serum total protein, relative to hemolytic reaction and blood volume before
and after transfusion were observed. The results showed that after transfusion of CSRBC or whole blood 27 cases were negative
for urine protein and UOB, and the levels of BUN and Cr were normal (P>0.05). Blood TB, DB, Hb, and HCT were increased, while pH, blood K+ and blood Na+ was normal with the difference being not significant before and after operation (P>0.05). Plasma protein was decreased, but there was no significant difference before and after operation (P>0.05). It was suggested that CSRBC or whole blood at −80 °C could be safely infused to the Rh(D) negative patients without
side effects during the surgical operation.
YU Zhongqing, male, born in 1957, Technician in Charge 相似文献
1000.
Pamela Husmann Christoph Bourauel Michael Wessinger Andreas J?ger 《Journal of orofacial orthopedics》2002,22(5):199-211
Background: The vast range of orthodontic wires made of different alloys makes it increasingly difficult for orthodontists to judge them. Coated orthodontic wires form a group of innovative guiding archwires. Material and Methods: In the present in vitro study the frictional behavior of eight coated wires of different dimensions was investigated in archwire-guided canine retraction in the upper jaw. For this purpose five superelastic nickel titanium alloy wires (Titanol/reg; Low Force River Finish Gold and Gold 2: Forestadent®, Pforzheim Germany; Titanol® Superelastic tooth Sentalloy Ionguard: GAC, Central Islip, NY, USA; NITI Imagination: GAC, Central Islip, NY, USA), two #-titanium wires (TMA® Low Friction Ionguard: Ormco, Glendora, CA, USA; TMA® Low Friction Ionguard Purple: Ormco, Glendora, CA, USA) and one steel wire (Stainless steel Imagination: GAC, Central Islip, NY, USA) were selected. The coatings were made of Teflon® or polyethylene, and by ion implantation. Three uncoated archwires (Rematitan® Lite Dimple; Dentaurum, Pforzheim, German; Titanol® Low Force River Finish: Forestadent®, Pforzheim, Germany; BioForce Sentalloy: GAC, Central Islip, NY, USA) were used for comparison purposes. The force losses due to friction were measured using the Orthodontic Measurement and Simulation System (OMSS). Results: The results indicated that all coatings can reduce frictional losses compared with an uncoated reference wire by the same manufacturer. Measured frictional losses ranged from 48.3-6.1% with the Teflon® coatings reducing the frictional losses to less than 10% in some cases. Conclusion: An unequivocal correlation between the surface roughness and frictional forces of the wires could not be verified by scanning electron microscopy. Zusammenfassung Hintergrund: Die Vielzahl an orthodontischen Drähten aus diversen Legierungen macht es die Kieferorthopäden immer schwerer, sie zu beurteilen. Eine Gruppe von neu angebotenen Führungsbögen stellen die beschichteten orthodontischen Drähte dar. Material und Methode: In der vorliegenden In-vitro-Studie wurde das Reibungsverhalten von acht beschichteten Drähten unterschiedlicher Dimension bei den bogengeführten Eckzahnretraktion im Oberkiefer untersucht. Neben fünf Nickel-Titan-Drähten (Titanol® Low Force River Finish Gold und Gold 2: Fa. Forestadent®; Titanol® Superelastic zahnfarben: Fa. Forestadent®; BioForce Sentalloy Ionguard: Fa. GAC; NiTi Imagination: Fa. GAC) wurden zwei #-Titan- (TMA Low Friction Iongard: Fa. Ormco; TMA Low Friction Ionguard Purple: Fa. Ormco) und ein Stahldraht (Stainless Steel Imagination: Fa. GAC) ausgewählt. Die Beschichtungen bestanden aus Teflon®, Polyethylen oder Ionenimplantation. Als Referenz wurden drei unbeschichtete Drähte (Rematitan® Lite Dimple: Fa. Dentaurum; Titanol® Low Force River Finish: Fa. Forestadent®; BioForce Sentalloy: Fa. GAC) in die Untersuchung einbezogen. Die Reibungsverluste wurden mit dem Orthodontischen Mess- und Simulations-System (OMSS) bestimmt. Ergebnisse: Die Ergebnisse zeigten, dass alle Beschichtungen, verglichen mit einem unbeschichteten Referenzdraht desselben Herstellers, eine Reduktion der Reibungsverluste bewirken. Die gemessenen Reibungsverluste lagen zwischen 48,3% und 6,1%, wobei bei Teflon®-Beschichtungen der Reibungsverlust zum Teil auf unter 10% sank. Schlussfolgerung: Ein eindeutiger Zusammenhang zwischen der Oberflächenrauheit und den Friktionswerten der Drähte konnte anhand von rasterelektronenmikroskopischen Aufnahmen nicht bestätigt werden. 相似文献