全文获取类型
收费全文 | 6810篇 |
免费 | 100篇 |
国内免费 | 6篇 |
专业分类
耳鼻咽喉 | 265篇 |
儿科学 | 260篇 |
妇产科学 | 371篇 |
基础医学 | 280篇 |
口腔科学 | 122篇 |
临床医学 | 370篇 |
内科学 | 1412篇 |
皮肤病学 | 316篇 |
神经病学 | 285篇 |
特种医学 | 503篇 |
外科学 | 1954篇 |
综合类 | 33篇 |
一般理论 | 1篇 |
预防医学 | 195篇 |
眼科学 | 256篇 |
药学 | 26篇 |
中国医学 | 1篇 |
肿瘤学 | 266篇 |
出版年
2018年 | 22篇 |
2017年 | 17篇 |
2016年 | 29篇 |
2015年 | 502篇 |
2014年 | 563篇 |
2013年 | 559篇 |
2012年 | 563篇 |
2011年 | 509篇 |
2010年 | 579篇 |
2009年 | 552篇 |
2008年 | 562篇 |
2007年 | 492篇 |
2006年 | 458篇 |
2005年 | 390篇 |
2004年 | 262篇 |
2003年 | 50篇 |
2002年 | 9篇 |
2001年 | 14篇 |
2000年 | 9篇 |
1999年 | 35篇 |
1998年 | 27篇 |
1997年 | 49篇 |
1996年 | 42篇 |
1995年 | 28篇 |
1994年 | 26篇 |
1993年 | 30篇 |
1992年 | 18篇 |
1991年 | 26篇 |
1990年 | 20篇 |
1989年 | 23篇 |
1988年 | 21篇 |
1987年 | 15篇 |
1986年 | 18篇 |
1985年 | 9篇 |
1984年 | 14篇 |
1983年 | 29篇 |
1982年 | 30篇 |
1981年 | 29篇 |
1980年 | 23篇 |
1979年 | 22篇 |
1977年 | 11篇 |
1976年 | 11篇 |
1975年 | 10篇 |
1959年 | 21篇 |
1958年 | 17篇 |
1957年 | 23篇 |
1956年 | 8篇 |
1955年 | 20篇 |
1954年 | 14篇 |
1948年 | 13篇 |
排序方式: 共有6916条查询结果,搜索用时 15 毫秒
61.
PD Dr. J. Bauer U. Bartram J. Thul D. Schranz 《Monatsschrift für Kinderheilkunde》2007,155(11):1040-1047
The morbidity in the long-term course following heart transplantation in childhood is mainly determined by the morbidity of the transplanted graft, by side effects caused by immunosuppression and by psychosocial morbidity due to the special situation of life and growing up with a transplanted heart. Transplant vasculopathy as a specific disease of the transplanted organ itself, is a common complication following heart transplantation and is an important factor of morbidity and mortality, considerably limiting the long-term prognosis. Progressive disturbance of renal function and cumulative incidence of malignant tumors is a further factor limiting prognosis caused by the side effects of immunosuppression. 相似文献
62.
Grotemeyer KH 《Schmerz (Berlin, Germany)》1992,6(1):82-91
Ohne Zusammenfassung 相似文献
63.
Kim YH; de Kretser DM; Temple-Smith PD; Hearn MT; McFarlane JR 《Molecular human reproduction》1997,3(4):307-313
Using mechanical and chemical dissection methods, fibrous sheath was
isolated both from normal ejaculated human spermatozoa and from rabbit
cauda epididymal spermatozoa. The same techniques did not produce a pure
preparation of fibrous sheath from ejaculated rabbit spermatozoa,
suggesting that further cross-linking and stabilization of sperm structures
occurs in response to components of the seminal plasma. The isolation
procedures were monitored by phase contrast microscopy and the purity of
the fibrous sheath was verified by electron microscopy. Sodium dodecyl
sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of isolated human
fibrous sheath revealed at least 14 protein bands of which the most
intensely stained were of molecular weight 84, 72, 66.2, 57, 32 and 28.5
kDa. The rabbit fibrous sheath revealed at least 10 protein bands, of which
the most intensely stained were 35.2, 32.7 and 28.5 kDa. The amino acid
composition of the purified fibrous sheath from human and rabbit
spermatozoa was similar, being high in aspartic acid and/or asparagine and
glutamic acid and/or glutamine, serine, alanine, leucine, lysine and
glycine, but low in histidine, tyrosine and isoleucine. This composition is
similar to that reported for the rat and suggests that mammalian sperm tail
fibrous sheaths are composed of similar types of proteins, although there
are apparent differences in protein components between species.
相似文献
64.
JUAN C. DE LA TORRE MARGARET MALLORY MICHELLE BROT LISA GOLD GEORGE KOOB MICHAEL B. A. OLDSTONE ELIEZER MASLIAH 《Virology》1996,220(2):508
Neurons have a restricted expression of MHC heavy chain molecules which prevents presentation of antigens of infecting viruses. As a result, such infected cells escape immune surveillance and allow the establishment of noncytolytic persistent infection. Here we show that a chronic noncytolytic viral infection bothin vitroandin vivoselectively perturbed the expression of GAP-43, a protein that plays a central role in neuronal plasticity processes accompanying learning and memory. GAP-43 expression was greatly decreased in the hippocampus, an area of heightened viral replication, while synaptic density was preserved. Concurrently, the ability to learn tasks was significantly impaired in these persistently infected mice. Yet, infected neurons remained free from structural injury. 相似文献
65.
66.
Lienou C Taziebou F-X Etoa B Nkegoum C A Pieme D PD Dzeufiet 《African journal of traditional, complementary, and alternative medicines》2007,4(2):127-134
This study was designed to evaluate the toxicity of the aqueous extract of Aspilia africana leaves. Oral doses of 500 mg/kg and 1000 mg/kg were administered for 28 days to rats after every 2 days for sub-acute toxicity. For acute toxicity, 5 doses of 2, 4, 8, 12 and 16g/Kg body weight were investigated in mice. The control groups consisted of mice or rats administered with distilled water. The signs of toxicity fluctuated lightly from one mammal to another throughout the experiment. The liver, kidneys and heart weight of rats revealed no significant differences between the test groups and the control. The results indicated that the medium lethal dose (LD50) was found to be greater in females than males with an average of 6.6g/Kg body weight for both sexes. Regardless of the significant differences observed at certain points in some biochemical parameters (ALT, AST, ALP, Creatinine and Glutathione); none showed any linear dose responsiveness. On the other hand, most of the parameters investigated were found to be gender dependent. These results suggested that A Africana can be classified among substances with low toxicity. 相似文献
67.
68.
PD Dr. W. Singer B. Freeman J. Rauschecker 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1981,41(3-4):199-215
Summary and Conclusions In six dark reared, 4-weak-old kittens visual experience was restricted to contours of a single orientation, horizontal or vertical, using cylindrical lenses. Subsequently, the deoxyglucose method was used to determine whether these artificial raising conditions had affected the development of orientation columns in the visual cortex. After application of the deoxyglucose pulse one hemifield was stimulated with vertical, the other with horizontal contours. Thus, from interhemispheric comparison, changes in columnar systems corresponding to experienced and inexperienced orientations could be determined. The following results were obtained: (1) Irrespective of the restrictions in visual experience, orientation columns develop in areas 17, 18, 19 and in the visual areas of the posterior suprasylvian sulcus. (2) Within area 17, spacing between columns encoding the same orientations is remarkably regular (1 mm), is not influenced by selective experience and shows only slight interindividual variation. (3) In non-striate areas the spacing of columns is less regular and the spatial frequency of the periodicity is lower. (4) The modifiability of this columnar pattern by selective experience is small within the granular layer of striate cortex but substantial in non-granular layers: Within layer IV columns whose preference corresponds to the experienced orientation are wider and more active than those encoding the orthogonal orientation but the columnar grid remains basically unaltered. Outside layer IV the columnar system is maintained only for columns encoding the experienced orientations. The deprived columns by contrast frequently fail to extend into non-granular layers and remain confined to the vicinity of layer IV. (5) These modifications in the columnar arrangement are more pronounced in striate cortex than in non-striate visual areas and, within the former, more conspicuous in the central than in the peripheral representation of the visual field. It is concluded that within layer IV the blue print for the system of orientation columns is determined by genetic instructions: first order cells in layer IV develop orientation selectivity irrespective of experience whereby the preference for a particular orientation is predetermined by the position in the columnar grid. Dependent on experience is, however, the expansion of the columnar system from layer IV into non-granular layers. It is argued that all distortions following selective rearing can be accounted for by competitive interactions between intracortical pathways, the mechanisms being identical to those established for competitive processes in the domain of ocular dominance columns. It is proposed that such experience dependent modifiability of connections between first and second order cells is a necessary prerequisite for the development of orientation selectivity in cells with large and complex receptive fields.This work has partially been supported by a grant from the Deutsche Forschungsgemeinschaft, SFB 50, A14Dedicated to Prof. D. Ploog on the occasion of his 60th anniversaryResearch Fellow of the Alexander-von Humboldt-Stiftung 相似文献
69.
PD Dr. W. Vetter H. Vetter W. Tenschert U. Kuhlmann A. Studer K. Glänzer G. Pouliadis F. Largiader J. Furrer W. Siegenthaler 《Journal of molecular medicine (Berlin, Germany)》1979,57(17):863-873
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
70.
Experimental determination of the kinetics of calcium-binding with chondroitin sulphate and the effects of uric acid on this process 总被引:1,自引:0,他引:1
Summary The calcium-binding kinetics of chondroitin sulphate C (CS) have been determined using equilibrium analysis including 45Ca. There is a linear relationship between the extent of the Ca binding and the concentration of CS present. 1 mol CS disaccharide unit binds 0.757 mol Ca. Scatchard plots of the data have revealed a single constant of dissociation (K
D
=1429). In the presence of urate ions, and dependent on the pH value, the ability of CS to bind Ca may be impaired by as much as 31%. These measurements have supported the theory that urate ions interact with the GAGs in urine. 相似文献