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   1919篇
  免费   97篇
  国内免费   26篇
耳鼻咽喉   22篇
儿科学   83篇
妇产科学   94篇
基础医学   307篇
口腔科学   35篇
临床医学   190篇
内科学   452篇
皮肤病学   55篇
神经病学   94篇
特种医学   57篇
外科学   217篇
综合类   42篇
预防医学   137篇
眼科学   31篇
药学   168篇
中国医学   16篇
肿瘤学   42篇
  2022年   12篇
  2021年   23篇
  2019年   11篇
  2018年   26篇
  2017年   17篇
  2016年   35篇
  2015年   25篇
  2014年   41篇
  2013年   54篇
  2012年   52篇
  2011年   67篇
  2010年   63篇
  2009年   50篇
  2008年   65篇
  2007年   67篇
  2006年   75篇
  2005年   66篇
  2004年   66篇
  2003年   53篇
  2002年   70篇
  2001年   76篇
  2000年   77篇
  1999年   64篇
  1998年   35篇
  1997年   45篇
  1996年   27篇
  1995年   31篇
  1994年   20篇
  1993年   29篇
  1992年   54篇
  1991年   40篇
  1990年   45篇
  1989年   38篇
  1988年   41篇
  1987年   33篇
  1986年   44篇
  1985年   45篇
  1984年   37篇
  1983年   28篇
  1982年   23篇
  1981年   19篇
  1980年   10篇
  1979年   17篇
  1978年   15篇
  1977年   15篇
  1976年   14篇
  1975年   16篇
  1974年   11篇
  1965年   10篇
  1964年   10篇
排序方式: 共有2042条查询结果,搜索用时 31 毫秒
21.
In recent years there have been many studies demonstrating a correlation between increased arterial blood pressure and altered lipid profiles, and there has been an especially positive correlation between high cholesterol levels and blood pressure. There are differences between the various reports that are important. In our study the lipid distribution in 105 hypertensive patients with mild or moderate arterial hypertension according to WHO criteria without clinically or ultrasonographically apparent atherosclerosis was compared to the lipid distribution in 65 age-matched healthy persons. On the epidemiological level a significant, positive association was found between LDL serum levels (P 0.001), Apo B serum levels (P 0.001), serum triglyceride levels (P 0.05) and VLDL serum levels (P 0.01) and arterial hypertension. However, in contrast to recent reports, no significant difference was found between total serum cholesterol levels in normotensives and hypertensives, and there was no difference in HDL serum levels. No evidence could be found for a significant increase in lipoprotein (a) serum levels in hypertensives.Abbreviations LDL low density lipoprotein - VLDL very low density lipoprotein - HDL high density lipoprotein - Apo B 100 apolipoprotein B 100 - Apo A I apolipoprotein A I Correspondence to: H. Vetter  相似文献   
22.
Niederwieser  A.  Joller  P.  Seger  R.  Blau  N.  Prader  A.  Bettex  J. D.  Lüthy  R.  Hirschel  B.  Schaedelin  J.  Vetter  U. 《Journal of molecular medicine (Berlin, Germany)》1986,64(7):333-337
Summary An increase in total urinary neopterin was observed in 12 of 13 patients with acquired immunodeficiency syndrome (AIDS), seven of 13 patients with lymphadenopathy, one of six healthy homosexual males, seven of ten adult patients with staphylococcal pneumonia, 11 of 12 children with viral infections, four of seven children with bacterial infections, and 12 of 13 children with various immune defects. Extremely high values of total urinary neopterin and monapterin were observed in severely ill patients with AIDS and those with familial hemophagocytic lymphohistiocytosis. Neopterin excretion was normal in two AIDS patients with Kaposi's sarcoma, but without opportunistic infections at that time. On reexamination of one of these patients later on, elevated neopterin values were noted. Parallel increases in neopterin and monapterin were found, whereas biopterin was usually normal. The increase in total neopterin was mainly due to 7,8-dihydroneopterin and was accompanied by an increase in 3-hydroxysepiapterin. Increased neopterin in urine is assumed to reflect the increase in GTP pool and GTP cyclohydrolase I activity as observed in stimulated monocytes. Thus, neopterin, as a measure of the activation of the nonspecific cellular immune system, may be used diagnostically to detect allograft rejection after transplantations and to follow-up HTLV-III positive patients.
Neopterin bei AIDS, anderen Immundefekten, Bakteriellen und viralen Infektionen
Abbreviations AIDS acquired immunodeficiency syndrome - ARC AIDS related complex - BH4 tetrahydrobiopterin - GTP guanosine triphosphate Supported by the Swiss National Science Foundation, project 3.266-0.82 and 3.601-0.84  相似文献   
23.
In 1965-66, a prospective psychosomatic investigation was started with 1,353 relatively old inhabitants of the village of Crvenka, Yugoslavia. The present article reports on the relevance of smoking for the incidence of lung cancer and cardiac infarct. The main results are: (1) The relevance of smoking is reduced, but not eliminated, by introducing psychosocial control variables, suggesting that the latter have direct influences both on smoking and on the diseases. (2) The relevance of smoking interacts very strongly with psychosocial background conditions: it is nearly reduced to zero when the latter are favorable, and is correspondingly high when they are unfavorable. The results are also interpreted in biochemical terms.  相似文献   
24.
Zusammenfassung Ein Radioimmunoassay für Angiotensin I und seine Anwendung für die Messung der Reninkonzentration im Plasma werden beschrieben. Die zur Herstellung von Angiotensinantikörpern und radioaktiv markiertem Angiotensin sowie zur Trennung von gebundenem und freiem Hormon benutzten Verfahren werden mitgeteilt. Die Empfindlichkeit der Methode erlaubt den Nachweis von zwanzig Pikogramm Angiotensin I.Zur Messung der Reninkonzentration wurde substratfreies Plasma mit Schafsubstrat im Überschuß versetzt und in Anwesenheit von Inhibitoren von converting enzyme und Angiotensinasen bei 37°C inkubiert. Das gebildete Angiotensin wurde in 20 µl des proteinfreien Inkubationsgemisches bestimmt. Die initiale Geschwindigkeit der Angiotensinbildung wurde zur Berechnung der Reninkonzentration herangezogen. Als eine Einheit wurde die Reninmenge definiert, die ein Nanogramm Angiotensin I pro Stunde Inkubation bildet.Normalwerte unter kontrollierter natriumreicher und natriumarmer Diät wurden ermittelt.Die Empfindlichkeit der Methode erlaubt die Messung der Reninkonzentration im Plasma von Patienten mit primärem Aldosteronismus.Mit Unterstützung der Deutschen Forschungsgemeinschaft.  相似文献   
25.
A new method to assess attachment representations in children by applying a story completion procedure in doll play (SCPDP) is presented. Transmission and continuity of attachment were tested in 28 German families by using the Strange Situation procedure (SS) with the mother and her infant, the Adult Attachment Interview (AAI) with the mother when the child is 5 years old, and the attachment representations (SCPDP) of the 6-year-olds. Relying on the twofold distinction (secure/insecure), results revealed a significant continuity of attachment from 1 to 6 years of age, and a correspondence between maternal AAI and child's attachment quality in SS, as well as a correspondence between maternal AAI and the 6-year-olds' attachment representations. Using configural frequency analysis, we found continuity in patterns of security and insecurity when looking across the measures of infant and pre-school attachment and maternal adult attachment. Processes underlying the high match of mothers' and children's attachment representations are discussed.  相似文献   
26.
Summary To analyse the role of the renin angiotensin system in the pathogenesis of hypertension in Cushing's syndrome ten patients with hypercorticism (five with pituitary hypothalamic dysfunction, three with adrenal adenomas and two with adrenal carcinomas) received a single oral dose of 25 mg captopril. Mean arterial pressure was then determined at short intervals over periods of up to 240 min. Plasma renin activity (PRA) was measured immediately before the administration of captopril. Eleven patients with severe essential hypertension, who showed a comparable distribution of basal PRA values, served as a control. Patients with elevated basal PRA values (>3 ng/ml·3 h) showed, both in the subgroup of cases with essential hypertension and in that with Cushing's syndrome, a statistically significant fall (P<0.05–P<0.001) in mean arterial pressure, the decrease being slightly more pronounced in essential hypertensives. On the other hand patients with normal PRA values (3 ng/ml·3 h) exhibited only a minor fall in mean arterial pressure reaching statistical significance (P<0.05) only after 60 min (essential hypertension) and 180 min (Cushing's syndrome), respectively. Our results document that in patients with Cushing's syndrome the effect of captopril seems to be determined by the activity of the renin angiotensin system. Thus, in a substantial number of patients with hypercorticism, the renin angiotensin system may be an important factor in the pathogenesis of hypertension, whereas in patients with low PRA values other factors like oversecretion of mineralocorticoids may be responsible for the observed blood pressure increases.  相似文献   
27.
In this paper, we report on the clinical application of fully automated three-dimensional intensity modulated proton therapy, as applied to a 34-year-old patient presenting with a thoracic chordoma. Due to the anatomically challenging position of the lesion, a three-field technique was adopted in which fields incident through the lungs and heart, as well as beams directed directly at the spinal cord, could be avoided. A homogeneous target dose and sparing of the spinal cord was achieved through field patching and computer optimization of the 3D fluence of each field. Sensitivity of the resultant plan to delivery and calculational errors was determined through both the assessment of the potential effects of range and patient setup errors, and by the application of Monte Carlo dose calculation methods. Ionization chamber profile measurements and 2D dosimetry using a scintillator/CCD camera arrangement were performed to verify the calculated fields in water. Modeling of a 10% overshoot of proton range showed that the maximum dose to the spinal cord remained unchanged, but setup error analysis showed that dose homogeneity in the target volume could be sensitive to offsets in the AP direction. No significant difference between the MC and analytic dose calculations was found and the measured dosimetry for all fields was accurate to 3% for all measured points. Over the course of the treatment, a setup accuracy of +/-4 mm (2 s.d.) could be achieved, with a mean offset in the AP direction of 0.1 mm. Inhalation/exhalation CT scans indicated that organ motion in the region of the target volume was negligible. We conclude that 3D IMPT plans can be applied clinically and safely without modification to our existing delivery system. However, analysis of the calculated intensity matrices should be performed to assess the practicality, or otherwise, of the plan.  相似文献   
28.
Summary Interrelations between age and plasma renin, aldosterone and cortisol levels, urinary catecholamines, plasma and blood volumes, exchangeable body sodium and blood pressure were studied in 28 young (19 to 29 years), 16 middle-aged (32 to 58 years) and 15 elderly (60 to 74 years) healthy subjects. Supine and upright plasma renin and supine aldosterone levels decreased while urinary noradrenaline excretion rate increased progressively with aging (r0.34;p<0.05), with significant differences in mean values between young and elderly subjects (p<0.02). There was also an age-related decrease in upright plasma aldosterone concentration, although this was not statistically significant. Furthermore, mean plasma cortisol concentrations increased in response to upright posture in elderly (+50%;p<0.02), but not in young (–10%) or middle-aged (–8%) subjects. Blood pressure correlated with age (r=0.35;p<0.05) or noradrenaline excretion rate (r=0.34) in the entire study population and with blood volume in the elderly (r=0.68), but not in the young or middle-aged study groups. There were no significant age-related differences in the body sodium/volume state, basal plasma cortisol levels or urinary adrenaline excretion rate, and plasma renin or aldosterone levels did not correlate with these parameters or with blood pressure. It is concluded that the influence of age on plasma renin or aldosterone levels, plasma cortisol responsiveness to upright posture, and urinary noradrenaline excretion should be taken into consideration, whenever these factors have to be interpreted in patients with arterial hypertension or other clinical disorders. Furthermore, these data are consistent with the possibility that in normal man increases in supine blood pressure with aging may be related at least partly to concomitant changes in free peripheral noradrenaline.This investigation was supported by the Swiss National Science Foundation  相似文献   
29.
Zusammenfassung In der vorliegenden Untersuchung wurde das postoperative Blutdruckverhalten bei 35 Patienten mit renovaskulärer Hypertonie untersucht: 17 Patienten mit fibromuskulärer Dysplasie (FMD) und 18 mit arteriosklerotischen Gefäßwandveränderungen (ASS).Patienten mit FMD waren im Mittel jünger (31,8 Jahre), zeigten eine kürzere Hypertonieanamnese (1,8 Jahre) und waren prävalent weiblich (82%), während Patienten mit ASS deutlich älter waren (48,2 Jahre), eine längere Hypertoniedauer (2,6 Jahre) zeigten und bevorzugt männlich (78%) waren.In beiden Gruppen zeigte das intravenöse Pyelogramm einen vergleichbar hohen Anteil positiver Befunde (FMD=64%, ASS=61%).Postoperativ waren in der Gruppe mit FMD 47% (n=8) geheilt, 47% (n=8) gebessert und nur 6% (n=1) der Patienten geringgradig gebessert. Die vergleichbaren Werte für die Gruppe mit ASS betrugen 28, 55 und 17%. Für das Gesamtkollektiv war folglich ein guter Operationserfolg (geheilt und gebessert) in 88,5% der Fälle zu beobachten. Patienten mit ASS und postoperativ nur geringgradiger Besserung (n=3) zeigten eine auffallend lange Hypertonieanamnese (7,0±1,4 Jahre).Bei allen Patienten wurde präoperativ die seitengetrennte Bestimmung der Renin-Aktivität (PRA) im Nierenvenenblut durchgeführt und aus den Werten die PRA-Quotienten (PRA betroffene/nicht betroffene Seite) errechnet. Bei 27 Patienten wurde die Bestimmung 15 und 30 min nach intravenöser Stimulation mit 40 mg Furosemid wiederholt. PRA-Quotienten von 1,5 wurden als signifikant bezeichnet.Bei 31 Patienten mit einseitiger renovaskulärer Hypertonie wurde die Höhe des PRA-Quotienten zum postoperativen Blutdruckverhalten korreliert. Dabei zeigte sich zwischen der Gruppe der postoperativ Geheilten und der der postoperativ Gebesserten kein signifikanter Unterschied im mittleren PRA-Quotienten. Ferner ließen sich für das Gesamtkollektiv der 31 Patienten mit einseitiger renovaskulärer Hypertonie unter Ausgangs- und Stimulationsbedingungen keine signifikanten Korrelationen zwischen Höhe der PRA-Quotienten und postoperativem Blutdruckabfall ermitteln.Unsere Ergebnisse unterstützen nicht die weit verbreitete Ansicht, daß sich die seitengetrennte Bestimmung der PRA im Nierenvenenblut als Parameter für den zu erwartenden Operationserfolg bei Patienten mit einseitiger renovaskulärer Hypertonie eignet. Die Methode kann deshalb nach unserer Ansicht nicht mehr als obligater Bestandteile der präoperativen Diagnostik der renovaskulären Hypertonie empfohlen werden.  相似文献   
30.
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