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   8653篇
  免费   603篇
  国内免费   36篇
耳鼻咽喉   154篇
儿科学   247篇
妇产科学   173篇
基础医学   1030篇
口腔科学   169篇
临床医学   1121篇
内科学   1591篇
皮肤病学   132篇
神经病学   721篇
特种医学   311篇
外国民族医学   2篇
外科学   1164篇
综合类   136篇
一般理论   11篇
预防医学   1001篇
眼科学   216篇
药学   617篇
中国医学   12篇
肿瘤学   484篇
  2023年   48篇
  2022年   91篇
  2021年   189篇
  2020年   120篇
  2019年   172篇
  2018年   171篇
  2017年   131篇
  2016年   153篇
  2015年   195篇
  2014年   281篇
  2013年   359篇
  2012年   481篇
  2011年   485篇
  2010年   289篇
  2009年   252篇
  2008年   430篇
  2007年   409篇
  2006年   359篇
  2005年   385篇
  2004年   294篇
  2003年   288篇
  2002年   286篇
  2001年   207篇
  2000年   210篇
  1999年   210篇
  1998年   117篇
  1997年   109篇
  1996年   95篇
  1995年   84篇
  1994年   83篇
  1993年   62篇
  1992年   149篇
  1991年   128篇
  1990年   157篇
  1989年   111篇
  1988年   137篇
  1987年   123篇
  1986年   103篇
  1985年   113篇
  1984年   93篇
  1983年   75篇
  1982年   76篇
  1981年   51篇
  1979年   79篇
  1978年   69篇
  1976年   50篇
  1975年   56篇
  1973年   63篇
  1972年   55篇
  1969年   54篇
排序方式: 共有9292条查询结果,搜索用时 15 毫秒
51.
May JG  Brown JM  Roberts S 《Vision research》1999,39(18):3025-3031
Under some conditions (dark or light inspection areas) illusory gratings often appear to be in-phase with the inducing gratings and under others (gray inspection area) illusory gratings often appear to be out-of-phase with the inducing gratings. McCourt reported that point-by-point brightness matches reveal only out-of-phase illusory gratings, no matter what the luminance of the inspection area (McCourt, M. E. (1994). Vision Research, 34, 1609-1617). Since the technique used might have led to afterimages which mimic out-of-phase illusory gratings, the present series of experiments was undertaken to determine how such afterimages might bias illusory grating judgments. Afterimages were induced during fixation with brief flashes of inducing gratings within the inspection area (Experiment 1), or by vertical shifts in the entire stimulus which exposed the retina to real gratings prior to judgments within the inspection area (Experiment 2). Experiment 2 was replicated with drifting inducing gratings (Experiment 3). The subjects were asked to indicate whether illusory gratings appeared in- or out-of-phase. The results of all three experiments reveal that out-of-phase illusory gratings predominate, and that afterimages can only bias judgments with stationary displays. It is suggested that grating induction is perceived when subjects attend to local contrast differences, while phantom visibility is facilitated when attention is captured by the more global aspects of the stimulus.  相似文献   
52.
Ligands for the CCR1 receptor (MIP-1alpha and RANTES) have been implicated in a number of chronic inflammatory diseases, most notably multiple sclerosis and rheumatoid arthritis. Because these ligands share a common receptor, CCR1, we sought to discover antagonists for this receptor as an approach to treating these disorders. A novel series of 4-hydroxypiperidines has been discovered by high throughput screening (HTS) which potently inhibits the binding of MIP-1alpha and RANTES to the recombinant human CCR1 chemokine receptor. The structure-activity relationships of various segments of this template are described as the initial HTS lead 1 was optimized synthetically to the highly potent receptor antagonist 6s. This compound has been shown to have at least 200-fold selectivity for inhibition of CCR1 over other human 7-TM receptors, including other chemokine receptors. In addition, data obtained from in vitro functional assays demonstrate the functional antagonism of compound 6s and structurally related analogues against the CCR1 receptor in a concentration dependent manner. The discovery and optimization of potent and selective CCR1 receptor antagonists represented by compound 6s potentially represent a novel approach to the treatment of chronic inflammatory diseases.  相似文献   
53.
It is possible that some "postpsychotic depressions" may be a toxic effect of antipsychotic drugs. Out of a total of 94 schizophrenic patients, 28 developed a mild akinesia and 32 never developed extrapyramidal symptoms. Those who developed akinesia became less psychotic, but they also experienced a significant, although modest, increase in depression ratings. Successful treatment of the akinesia resulted in significant improvements in depression, somatic concern, anxiety, emotional withdrawal, blunted affect, and motor retardation on both physicians' and nurses' ratings. A high association between akinesia and both objectively rated and subjectively experienced sedative effect indicates that an 'akinetic depression' is not likely if the patient does not look or feel drowsy. The 32 nonakinetic patients also became less psychotic, but not more depressed.  相似文献   
54.
55.
After 40 years of communism, Hungary is a tired nation. But now an enormous task faces its government; bringing its antiquated healthcare system into line with those of western Europe. Annabelle May reports from a conference in Budapest.  相似文献   
56.
57.
The mechanisms of action and clinical applications of electric differential treatment (EDiT) and Endosan in the treatment of ovarian cysts and concomitant symptoms are reviewed. Possible mechanisms of action include an increased level of cyclic AMP, stimulation of endorphin release, anti-inflammatory action, and steroidogenesis resulting from normalization of intercellular communication. Favorable results in the clinical setting were achieved in the treatment of ovarian cysts. Treatment success was reflected in a significant reduction in overall cyst size as well as amelioration of various concomitant symptoms, including fever, chills, inflammation, and abdominal pain. EDiT and Endosan were shown to have potent analgesic and anti-inflammatory effects. No adverse effects have been reported.  相似文献   
58.
Zusammenfassung Zusätzlich wurden physikalische und chemische Untersuchungen über den Einfluß von dynamischem Interferenzstrom (DIC) auf die Knochenheilung durchgeführt, nachdem bei 24 Schwarzkopfschafen eine Querosteotomie des Radius vorgenommen worden war. Nach instabiler Osteosynthese wurde die Osteotomiezone wiederholt mit DIC verschiedener mA—Stärken behandelt. (Methodische Einzelheiten sind in Teil I beschrieben). Die Behandlung mit dynamischem Interferenzstrom führte im behandelten Gewebe zu steigenden Temperaturen, die von den mA—Stärken abhängig waren. Weiterhin wurden Zusammenhänge zwischen DIC—mA—Intensität und dem Vorkommen von Hydroxyprolin, einer kollagenspezifischen Aminosäure, nachgewiesen, welches eine erhöhte Calcifizierungsaktivität zur Folge hatte. Messungen des Calcium— und Phosphorgehaltes im neugebildeten Knochengewebe wiesen bei den mit DIC behandelten Tieren vollständige Mineralisation zu einem viel früheren Zeitpunkt als bei den unbehandelten, nach gleichem Verfahren operierten Kontrolltieren auf. Ob DIC einen spezifischen Reiz auf die Knochenneubildung heilender Knochen ausübt, ist noch nicht vollständig geklärt.
Bone healing and Dynamic Interferential Current (DIC)
Summary In the course of supplementary physical and chemical investigations of the influence ofDynamicInterferential Current (DIC) on bone healing 24 black-head sheep were subjected to transversal osteotomy of the radius. After an instable osteosynthesis the site was exposed to repeated therapy with DIC of varying mA intensity. (Methodological details are described in part 1.) DIC therapy resulted in altering the temperatures in the treated tissue, dependent on the mA intensity. Further associations were verified between DIC intensity and the occurrence of hydroxyprolin, an amino acid specific collagen, which also reflected increased calcifying activity. Measurements of the calcium and phosphorus levels in the regenerated (newly forming) bone tissue documented full mineralization in the DIC-treated animals at a much earlier date than in the untreated controls that had undergone similar operations. Whether DIC specifically stimulates osteogenesis within healing bones is still unclear.
  相似文献   
59.
Willuhn G  May S 《Planta medica》1982,46(3):153-158
From tissue cultures (callus) of the soladulcidine strain of Solanum dulcamara L. the 4,4-dimethylsterols cycloartenol, cycloartanol, 24-dihydrolanosterol, and 24-methylenecycloartanol and the sterols cholesterol, 24-methylenecholesterol, campesterol, stigmasterol, isofucosterol, and sitosterol were identified by GC and GC/MS. In the callus the sterols are present in the free form and as esters, glucosides and palmitic esters of the glucosides. The total contents and the contents of the combined forms were determined photometrically (total: 0.19% on dry weight basis, 59.4% glucosides and acylated glucosides, 4.7% esters, 35.9% free). The main fatty acids of the petrolether soluble lipids of the callus (1.78%) are palmitic-, linoleic-, and linolenic acid.  相似文献   
60.
An experiment is described in which three male volunteers, who fully understood the nature of the project, were given doses of heroin which could have led to addiction if the subjects had proved to be physiologically or psychologically vulnerable to developing a state of addiction. The experiment was discussed most carefully by the Ethics Committee of the unit where it was conducted, and the subjects were themselves the investigators. The objective was to learn about the initial stages of the adaptation to heroin, of which nothing was known as heroin addicts usually come to the doctor when the habit is firmly established. A physician, who has studied the subject of drug addiction in a special clinic, is the first commentator, the second a lawyer and the third an associate professor of social ethics. These three experts are not discussing the results or the methodology of the experiment but whether the decision of the Ethics Committe was the right one.  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