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   6383篇
  免费   581篇
  国内免费   41篇
耳鼻咽喉   50篇
儿科学   108篇
妇产科学   300篇
基础医学   776篇
口腔科学   148篇
临床医学   707篇
内科学   1389篇
皮肤病学   80篇
神经病学   692篇
特种医学   336篇
外科学   710篇
综合类   131篇
一般理论   2篇
预防医学   371篇
眼科学   167篇
药学   375篇
中国医学   62篇
肿瘤学   601篇
  2023年   36篇
  2022年   69篇
  2021年   140篇
  2020年   83篇
  2019年   180篇
  2018年   203篇
  2017年   165篇
  2016年   185篇
  2015年   235篇
  2014年   268篇
  2013年   333篇
  2012年   462篇
  2011年   496篇
  2010年   298篇
  2009年   286篇
  2008年   364篇
  2007年   333篇
  2006年   396篇
  2005年   291篇
  2004年   294篇
  2003年   258篇
  2002年   233篇
  2001年   156篇
  2000年   143篇
  1999年   118篇
  1998年   53篇
  1997年   51篇
  1996年   40篇
  1995年   22篇
  1994年   27篇
  1993年   29篇
  1992年   76篇
  1991年   75篇
  1990年   58篇
  1989年   64篇
  1988年   38篇
  1987年   38篇
  1986年   48篇
  1985年   36篇
  1984年   30篇
  1983年   33篇
  1982年   24篇
  1981年   22篇
  1979年   20篇
  1978年   19篇
  1977年   16篇
  1975年   14篇
  1974年   30篇
  1973年   21篇
  1972年   18篇
排序方式: 共有7005条查询结果,搜索用时 15 毫秒
41.
X-box binding protein 1 (XBP1), a critical gene in the endoplasmic reticulum stress response, is located on chromosome 22q12, which has been linked with bipolar disorders in several studies. Recently, associations have been reported between a polymorphism (-116C --> G) in the promoter region of XBP1, and bipolar disorders in both case-control study and family-based association study, however, this finding is not yet confirmed by other research using independent sample populations. To replicate this finding and determine the association between onset age of bipolar disorders and the XBP1 C--116G polymorphism, we investigated the prevalence of this polymorphism in a Chinese population (153 bipolar disorder patients and 174 controls). We were unable, however, to demonstrate a significant association between the C--116G polymorphism and bipolar disorders (P = 0.674 for genotype and P = 0.436 for allele frequency) or age at onset (P = 0.563). Further, no association was demonstrated between this polymorphism and family history in bipolar disorder patients. These negative findings suggest that the XBP1 C--116G polymorphism does not play a major role in the pathogenesis of bipolar disorders in Chinese populations.  相似文献   
42.
The anatomy of the cardiac conduction system in normal and malformed hearts reconstructed from histological serial sections is reviewed. The sinus node and its arterial supply are located in the right superior cavoatrial junction except in hearts with left-sided juxtaposition of the atrial appendages, mirror-image, and isomeric arrangements of the atria. In the presence of normally positioned atrial and ventricular septal structures, the triangle of Koch is a useful guide to the location of the atrioventricular node and the penetrating bundle. In hearts with isolated ventricular septal defects, it is necessary to distinguish between a perimembranous defect and a muscular inlet defect. The conduction axis runs in the area of fibrous continuity at the posteroinferior edge of a perimembranous defect but in the anterosuperior rim of a muscular inlet defect. In most hearts with tetralogy of Fallot, the danger area is the region of aortic-mitral-tricuspid fibrous continuity where the axis penetrates. In hearts with atrioventricular septal defects, the lack of contiguity between atrial and ventricular septum results in a posterior displacement of the nodal triangle and coronary sinus and an elongation of the nonbranching bundle. Hearts with abnormally located atrioventricular nodes and conduction axes are mainly those with atrioventricular discordance, ambiguous atrioventricular connection in presence of left-hand pattern ventricular topology, hearts with univentricular atrioventricular connection to a morphologically left or indeterminate ventricle, and hearts with a straddling tricuspid valve. The location of the atrioventricular node is governed by the orientation of the ventricular septum and by the pattern of ventricular topology.
Resumen Se revisa la anatomía del sistema de conducción cardiaca en los corazones normales y con malformaciones a la luz de la reconstrucción a partir de cortes histológicos seriados. El nódulo sinusal y su irrigación arterial está ubicado en la unión cavoatrial derecha, excepto en corazones con yuxtaposición izquierda de las auriculillas o con alteraciones en imagen en espejo e isoméricas de las aurículas. En presencia de estructuras septales atriales y ventriculares normalmente ubicadas, el tríangulo de Koch es una guía útil para la localización del nódulo atrioventricular y la penetración del haz. En corazones con defectos septales ventriculares aislados es necesario distinguir entre un defecto perimembranoso y un defecto del tracto muscular de entrada. El haz de conducción avanza en el área de continuidad fibrosa sobre el borde posteroinferior de un defecto perimembranoso, en el filo anterosuperior de un defecto del tracto muscular de entrada. En la mayoría de los corazones con tetralogía de Fallot el área de peligro se encuentra en la región del trígono fibroso aórticomitral y tricuspídeo sobre el cual penetra el haz de conducción. En corazones con defectos septales atrioventriculares la falta de continuidad entre el septo atrial y el ventrícular resulta en un desplazamiento posterior del triángulo de Koch y del seno coronario y en una elongación del haz no ramificado. Corazones con nódulos atrioventriculares y haces de conducción anormalmente ubicados son principalmente aquellos con discordancia atrioventricular, con conexión atrioventricular ambigua en presencia de un patrón izquierdo de arquitectura ventricular, corazones con conexión atrioventricular univentricular a un ventrículo morfológicamente izquierdo o indeterminado y corazones con válvula tricuspídea cabalgante. La ubicación del nódulo atrioventricular está determinada por la orientación del septo ventricular y por el patrón de la arquitectura ventricular.

Résumé L'anatomie du système de conduction du coeur normal et du coeur siège de malformations reconstituée à partir de coupes sériées histologiques est exposée. Le sinus nodal et sa vascularisation sont situés au niveau de la partie supérieure de la jonction auriculo-ventriculaire droite sauf dans certains cas: coeur avec juxtaposition des auricules du côté gauche, image en miroir et dispositions isomères des oreillettes. Lorsque les cloisons auriculaire et ventriculaire occupent une situation normale, le triangle de Koch constitue un repère utile pour localiser le noyau auriculo-ventriculaire et le faisceau de His. En cas de défects septaux ventriculaires isolés, il est nécessaire de distinguer les défects périmembraneux et les défects musculaires. L'axe nerveux conducteur chemine dans la zone de continuité fibreuse au bord postéroinférieur du défect périmembraneux mais il chemine au bord antéro-supérieur du défect musculaire. En cas de tétralogie de Fallot, le danger se situe souvent au niveau de la zone fibreuse de continuité aortique-mitrale-tricuspide où pénètre l'axe conducteur. En cas de coeur porteur d'un défect septal auriculo-ventriculaire, le défaut de continuité entre la cloison ventriculaire et la cloison auriculaire entraîne le déplacement postérieur du triangle nodal et du sinus coronaire ainsi que l'élongation du faisceau. Les coeurs qui présentent une anomalie du siège des noyaux auriculo-ventriculaires et des nerfs conducteurs sont principalement ceux qui sont le siège d'une anomalie auriculo-ventriculaire, d'une connexion auriculo-ventriculaire ambiguë en cas d'une disposition ventriculaire de type gauche, d'une connexion auriculo-ventriculaire univentriculaire avec une morphologie ventriculaire gauche ou indeterminée, d'une valve tricuspide en fourche. Le siège du noyau auriculo-ventriculaire est fonction de l'orientation du septum ventriculaire et de l'architecture ventriculaire.


Supported by the British Heart Foundation.  相似文献   
43.
The protective effect of "San-fang-feng" derived from the root of Echinops grijsii Hance on CCl4-induced hepatotoxicity has been studied. This crude drug was found to possess a marked hepatoprotective effect. A comparison of the protective effect with "Lou-lu" derived from the root of E. latifolius Tausch and "Pei-chai-hu" original Bupleurum chinense showed that E. grijisii and E. latifolius were more effective than B. chinense as reported previously. The results suggested that both E. grijisii and E. latifolius could correct the hepatocyte necrosis and functional disorder induced by the CCl4 treatment.  相似文献   
44.
Herpes zoster and postherpetic neuralgia cause substantial pain in patients. Persons with type 2 diabetes (T2D) are prone to zoster infection and postherpetic neuralgia due to compromised immunity. We conducted this study to evaluate the risks of herpes zoster and postherpetic neuralgia between metformin users and nonusers. Propensity score matching was utilized to select 47 472 pairs of metformin users and nonusers from Taiwan's National Health Insurance Research Database between January 1, 2000, and December 31, 2017. The Cox proportional hazards models were used for comparing the risks of herpes zoster and postherpetic neuralgia between metformin users and nonusers in patients with T2D. Compared with no-use of metformin, the adjusted hazard ratios (95% confidence interval) for metformin use in herpes zoster and postherpetic neuralgia were 0.70 (0.66, 0.75) and 0.510 (0.39, 0.68), respectively. A higher cumulative dose of metformin had further lower risks of herpes zoster and postherpetic neuralgia than metformin no-use. This nationwide cohort study demonstrated that metformin use was associated with a significantly lower risk of herpes zoster and postherpetic neuralgia than metformin no-use. Moreover, a higher cumulative dose of metformin was associated with further lower risks of these outcomes.  相似文献   
45.
In patients with agenesis of the vagina and cervix but with a functional endometrium, the traditional treatment is hysterectomy with construction of a neovagina. We report successful treatment by laparoscopically assisted full thickness skin graft for reconstruction in a patient with congenital agenesis of the vagina and uterine cervix concomitant with haematometra and ovarian endometrioma in a 12 year old girl. Postoperatively, the vaginal skin graft healed well, and menstruation first appeared 4 weeks later. In our opinion, a combined laparoscopic and vaginal procedure with full thickness skin graft is an efficacious alternative in managing such genital defects.  相似文献   
46.
目的:验证国产氟西洒汀长期、大范围治疗抑郁性障碍的疗效和副反应。方法:采用国产氟西汀开放治疗抑郁性障碍30例,以HAMD和TESS评定症状、疗效和副反应。结果:氟西汀对各类型抑郁性障碍的疗效肯定;显效率达80%,副反应少且轻。结论:氟西汀是一种安全、有效、广谱的抗抑郁剂。  相似文献   
47.
This study assessed 11C-acetate turnover (clearance) in nasopharyngeal carcinoma (NPC). Data were acquired by dynamic PET after the intravenous injection of 4.625 MBq.kg-1 body weight of 11C-acetate for 30 min. Tomograms were reconstructed and evaluated visually. A time-activity curve of the nasopharynx and neck was generated and the clearance rate of 11C-acetate from the nasopharynx in the slow phase and from NPC was calculated using 0.693/T1/2. Ten patients with nasopharyngeal carcinoma and nine normal subjects were studied. The clearance of 11C-acetate from the normal nasopharynx was rapid and biexponential, in contrast to the rapid uptake followed by extremely slow clearance in patients with NPC. The clearance rate (mean +/- S.D.) was 0.0074 +/- 0.0042 in NPC and 0.0263 +/- 0.0152 in controls in the slow phase, being significantly different between the two groups with no overlap. All nasopharyngeal carcinomas were clearly visualized, in contrast to no obvious retention in the normal nasopharynx. Our initial results indicate that 11C-acetate clearance can be used to differentiate nasopharyngeal carcinoma from a normal nasopharynx. This finding may lead to new applications of 11C-acetate in oncology.  相似文献   
48.
Lin CL  Yen CP  Howng SL 《Surgery today》1999,29(3):209-213
To assess and compare the long-term results of upper dorsal sympathetic ganglionectomy (UDS) and endoscopic thoracic sympathectomy (ETS), we examined 84 patients who underwent UDS and 71 patients who underwent ETS for the treatment of palmar hyperhidrosis. The period of follow-up ranged from 37 to 228 months. The immediate success rate was 100% in the UDS group and 98.6% in the ETS group. Troublesome compensatory hyperhidrosis occurred in 67.8% of the UDS patients and 84.8% of the ETS patients; however, 55% of the UDS patients and 63% of the ETS patients felt satisfied with their operation. The main reasons for dissatisfaction were recurrence and compensatory hyperhidrosis. Interestingly, simultaneous cure of plantar hyperhidrosis occurred in 28 (40%) of the UDS patients and 28 (44%) of the ETS patients with concomitant plantar hyperhidrosis. ETS required both a shorter operation time and hospital stay than UDS. Thus, we now perform ETS as the treatment of choice because of its excellent illumination and adequate magnification via a minimally invasive approach. The use of ETS as the first choice of treatment for palmar hyperhidrosis is supported not only by the immediate results, complications, and cure of plantar hyperhidrosis, but also by the long-term results. Nevertheless, compensatory hyperhidrosis was also a major complication after ETS.  相似文献   
49.
Development and evaluation of a new composite Laserskin graft   总被引:5,自引:0,他引:5  
BACKGROUND: Tremendous effort has been made to improve the graft take rate of cultured epidermal autograph. The purpose of this study is to develop and evaluate a new composite Laserskin graft (CLSG) as a human skin substitute for wound resurfacing. METHODS: The seeding efficacy of cultured keratinocytes on plain Laserskin was compared with the 3T3 cell-seeded Laserskin and allogenic fibroblast-populated Laserskin. Three different types of CLSG, 2 cm in diameter each, were prepared and tested in rats. Type A CLSG consisted of proliferative allogenic rat fibroblasts on both sides of the Laserskin with autologous keratinocytes also on the upper side. Fibroblasts and keratinocytes were seeded only on the upper side of the Laserskin in type B CLSG. Keratinocytes alone were seeded on plain Laserskin in type C CLSG. Type B CLSG consisting of autologous keratinocytes and autologous dermal fibroblasts was tested on five selected wounds (5x5 cm each) of a patient with full-thickness burn. In another burn patient, type B CLSG consisting of autologous keratinocytes and allogenic dermal fibroblasts was grafted onto three wounds (5x5 cm each). RESULTS: The seeding efficacy of human keratinocytes on plain Laserskin increased from 75% to 95% when proliferative allogenic fibroblasts were grown as a feeder layer on the Laserskin. The seeding efficacy of rat keratinocytes increased from 36% to 88% in the presence of a proliferative allogenic fibroblast feeder layer, whereas human/rat keratinocytes had respective seeding efficacy of 98%/91% on Laserskin preseeded with mitomycin C-treated 3T3 cells. Skin biopsies of grafted type A CLSG on day 14 after grafting showed complete epithelialization without severe inflammation in 16 of 20 (80%) grafted surgical wounds in rats. There were eight (40%) and seven (35%) "takes" of the CLSG in types B and C, respectively. The infection rate in type B CLSG was two (10%). There was one (5%) infection in types A and C. The respective take rates on the two patients grafted with type B CLSG were 60% and 100%. CONCLUSION: The animal experiment and the preliminary clinical data showed that the CSLGs consisting of autologous keratinocytes and of autologous/allogenic fibroblasts are good human skin substitutes in terms of durability, biocompatibility, high seeding efficacy for keratinocytes, high graft take rate, and low infection rate.  相似文献   
50.
BACKGROUND AND OBJECTIVE: To develop an animal model for evaluation of femtosecond laser intrastromal refractive surgery. METHODS: Intrastromal photodisruption was performed in New Zealand Albino rabbits using a femtosecond laser system. This surgical pattern consisted of a 100 microm-tick pyramid of laser pulses starting 180 microm below the corneal surface. Animals underwent serial slit lamp examinations and corneal thickness measurements at 1,3,7,14, and 28 days, then monthly up to 1 year. RESULTS: Approximately 70 microm of central corneal thinning were seen at 1 week, remaining stable up to 7 months. CONCLUSIONS: Intrastromal photodisruption with femtosecond lasers produced consistent changes in corneal thickness without loss of corneal transparency. These changes were more stable than those produced with excimer laser procedures in a similar animal model.  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