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   41331篇
  免费   4085篇
  国内免费   753篇
耳鼻咽喉   1017篇
儿科学   1130篇
妇产科学   369篇
基础医学   6904篇
口腔科学   748篇
临床医学   2159篇
内科学   7354篇
皮肤病学   1279篇
神经病学   5797篇
特种医学   1326篇
外科学   5387篇
综合类   1802篇
现状与发展   2篇
预防医学   1244篇
眼科学   655篇
药学   4820篇
  5篇
中国医学   731篇
肿瘤学   3440篇
  2024年   21篇
  2023年   177篇
  2022年   544篇
  2021年   2103篇
  2020年   909篇
  2019年   1274篇
  2018年   1399篇
  2017年   1436篇
  2016年   1261篇
  2015年   1962篇
  2014年   2028篇
  2013年   1943篇
  2012年   1855篇
  2011年   1916篇
  2010年   1741篇
  2009年   1514篇
  2008年   1822篇
  2007年   1275篇
  2006年   1106篇
  2005年   1063篇
  2004年   1011篇
  2003年   1157篇
  2002年   1807篇
  2001年   2116篇
  2000年   2215篇
  1999年   1612篇
  1998年   1713篇
  1997年   1542篇
  1996年   959篇
  1995年   609篇
  1994年   453篇
  1993年   455篇
  1992年   310篇
  1991年   284篇
  1990年   242篇
  1989年   194篇
  1988年   194篇
  1987年   197篇
  1986年   274篇
  1985年   254篇
  1984年   231篇
  1983年   210篇
  1982年   197篇
  1981年   180篇
  1980年   129篇
  1979年   76篇
  1978年   47篇
  1977年   50篇
  1976年   28篇
  1975年   32篇
排序方式: 共有10000条查询结果,搜索用时 29 毫秒
81.
Gingival crevicular fluid (GCF) IL-8 and IL-1,1β levels were determined by sandwich enzyme-linked immunosorbent assays. Associations between IL-8 and IL-1β GCF levels, and between these cytokines and patient estrogen status were evaluated. IL-8 and IL-1β were detected more frequently and in higher amounts/30 s GCF sample in estrogen-deficient patients than in estrogensufficient patients. IL-8 and IL-1β GCF levels were significantly correlated. These lindings suggest that GCF IL-8 levels are associated with patient estrogen status and local IL-1β concentrations.  相似文献   
82.
Aim: Rheumatoid arthritis (RA) is the most common chronic inflammatory erosive joint disease with the worldwide distribution of approximately 0.5–1.0%. Etiology of RA is not exactly known but immunologic and genetic factors play an important role in the pathogenesis of the disease. Genetic factors such as human leukocyte antigens (HLA) are responsible for many autoimmune diseases; therefore we decided to look for a correlation between RA and the presence of HLA‐DQβ1 alleles as possible genetic markers. Methods: Genomic DNA from the whole blood samples of 25 patients with RA and 86 normal individuals as control group were extracted by salting out method. The genomic DNA was amplified by polymerase chain reaction‐sequence specific primer (PCR‐SSP) technique. HLA‐typing was done by this method after optimizing the PCR reaction for each allele. In this procedure seven serological subclasses of HLA‐DQβ1 can be detected. Results: Comparing the results between the patients and controls show a significant increase in the frequency of HLA‐DQ8 (*0302, *0305) alleles in RA patients. The P‐values were 0.007 and the relative risk for these alleles was evaluated higher than 1. Conclusions: The results suggest that DQ8 is the dominant HLA‐DQβ1 allele that is associated with susceptibility to RA in north‐eastern Iran.  相似文献   
83.
目的探讨CD11b在肺纤维化患者外周血中性粒细胞上的表达及红霉素对它的影响.方法肺纤维化患者(A组,n=13)13例经红霉素治疗3个月,收集治疗前后及健康对照组(B组,n=13)13例的外周血中性粒细胞涂片,用桥联酶免疫法测定CD11b表达阳性的中性粒细胞百分率.结果A组治疗前后,患者外周血中性粒细胞CD11b的表达阳性率均显著高于健康对照组(P<0.01);A组治疗前,患者外周血中性粒细胞CD11b的表达阳性率显著高于治疗后(P<0.01).结论肺纤维化患者外周血中性粒细胞CD11b的表达阳性率显著高于健康对照组;红霉素能抑制肺纤维化患者外用血中性粒细胞CD11b的表达.  相似文献   
84.
SK&F 86466, 6-chloro-3-methyl-2,3,4,5-tetrahydro-1-H-3-benzazepine, is a potent and selective antagonist of the α2-adrenoceptor in vitro. This compound produced a small pressor response accompanied by a marked bradycardia when administered i.v. to the pithed normotensive rat. The pressor response was not affected by reserpine treatment, pretreatment with α- or β-adrenoceptor antagonists, atropine, or hexamethonium. The bradycardia was markedly reduced by bilateral vagotomy and pretreatment with atropine and attenuated by hexamethonium. The negative chronotropic action of SK&F 86466 was abolished by a combination of vagotomy and atropine. Mediation of the bradycardia by a baroreceptor reflex was ruled out by the observations that a lack of change in heart rate was associated with the vasopressor response to phenylephrine in the pithed rat pretreated with propranolol. It is concluded that the negative chronotropic action of SK&F 86466 in the pithed rat is mediated indirectly by activation of the cholinergic innervation of the heart.  相似文献   
85.
Zusammenfassung Bericht über ?dintraoperative maschinelle autotransfusion?, kombiniert mit ?pr?operativer plasmapherese?. Mit maschineller autotransfusion kann intraoperativer blutverlust durch rückführung eigener erythrozyten halbiert werden. In kombination mit pr?operativer plasmapherese werden weitere fremdblutkonserven eingespart. übertragung von infektionskrankheiten und erzeugung irregul?rer antikōrper kōnnen verhindert werden. Bei der derzeitigen AIDS-situation wird das infektionsrisiko auf null reduziert.   相似文献   
86.
In very preterm neonates, bronchopulmonary dysplasia (BPD) complicates the course of respiratory distress syndrome, i.e., primary surfactant deficiency in a structural immature lung. In Germany, about 11 000 preterms having a gestational age below 32 weeks are born and treated in neonatal intensive care units per year. Within this high risk group, the rate of BPD is about 15%. Relevant prenatal risk factors include intrauterine inflammatory fetal reaction as a consequence of ascending maternal infections, intrauterine growth retardation apart from the main risk factor immaturity. Postnatal risk factors include genetic predisposition, mechanical ventilation, infections and hemodynamically relevant patent ductus arteriosus.Preventive measures include intratracheal surfactant administration; new studies indicate preventive effects of caffeine, vitamin A and hydrocortisone in a subgroup of neonates with prenatal fetal inflammatory response.Due to long-term detrimental effects of BPD on lung function and psychomotor development, further experimental and clinical studies are mandatory in order to continue to reduce the BPD rate.  相似文献   
87.
Zusammenfassung Fragestellung. Ziel der vorliegenden Untersuchung war, die Effekte der Sauerstoff tragenden freien H?moglobinl?sung (Diaspirin-crosslinked-H?moglobin, DCLHb) auf die kapillare Perfusion sowie die Oxygenation im quergestreiften Hautmuskelgewebe nach kritischer Isch?miezeit und nachfolgender Reperfusion zu analysieren. Material und Methode. Die kapillare Gewebeperfusion wurde anhand der funktionellen Kapillardichte im Hautmuskel des syrischen Goldhamsters quantitativ vor der Induktion einer 4-stündigen Isch?mie sowie nach 0,5 h, 2 h und 24 h Reperfusion mittels intravitaler Fluoreszenzmikroskopie erfasst (n=8 pro Versuchsgruppe). In separaten Tieren wurde nach demselben Versuchsansatz mit der Mehrdrahtoberfl?chenelektrode (MDO, Eschweiler, Kiel) die Gewebeoxygenation gemessen (n=8 pro Versuchsgruppe). Die Tiere der Testgruppe (n=8) erhielten 15 min vor der Reperfusion eine Kurzinfusion von 5 ml/kg KG DCLHb (Diaspirin-crosslinked-H?moglobin, 10 g/dl, Baxter, IL, USA). Die Kontrolltiere (n=8) erhielten ?quivalente Dosen einer isotonen Kochsalzl?sung (Braun, Melsungen). Ergebnisse. Die funktionelle Kapillardichte als Ma? für die L?nge von erythrozytenperfundierten Kapillaren pro Beobachtungsfeld war bei den Kontrolltieren in der Reperfusionsphase dramatisch vermindert, w?hrend bei den mit DCLHb behandelten Tieren signifikant h?here Werte nachweisbar waren (p<0,05). Diese Beobachtung spiegelte sich in einer vollst?ndigen Erholung des Gewebe-pO2 bei den Behandlungstieren wider, was in Kontrolltieren nicht erreicht wurde. Schlussfolgerungen. Die Ergebnisse dieser Studie zeigen, dass die Sauerstoff tragende L?sung DCLHb nach kritischer Isch?mie und Reperfusion die nutritive Perfusion und Gewebeoxygenation gegenüber kristalloiden L?sungen verbessert. Die Anwendung derartiger L?sungen scheint unter den klinischen Bedingungen einer kritischen Isch?mie daher als viel versprechender adjuvanter therapeutischer Ansatz. Electronic Publication  相似文献   
88.
AIMS: Diabetic ketoacidosis (DKA), a life-threatening acute complication of Type 1 diabetes, may be preventable with frequent monitoring of glycaemia and ketosis along with timely supplemental insulin. This prospective, two-centre study assessed sick day management using blood 3-hydroxybutyrate (3-OHB) monitoring compared with traditional urine ketone testing, aimed at averting emergency assessment and hospitalization. METHODS: One hundred and twenty-three children, adolescents and young adults, aged 3-22 years, and their families received sick day education. Participants were randomized to receive either a blood glucose monitor that also measures blood 3-OHB (blood ketone group, n = 62) or a monitor plus urine ketone strips (urine ketone group, n = 61). All were encouraged to check glucose levels > or = 3 times daily and to check ketones during acute illness or stress, when glucose levels were consistently elevated (> or = 13.9 mmol/l on two consecutive readings), or when symptoms of DKA were present. Frequency of sick days, hyperglycaemia, ketosis, and hospitalization/emergency assessment were ascertained prospectively for 6 months. RESULTS: There were 578 sick days during 21,548 days of follow-up. Participants in the blood ketone group checked ketones significantly more during sick days (276 of 304 episodes, 90.8%) than participants in the urine ketone group (168 of 274 episodes, 61.3%) (P < 0.001). The incidence of hospitalization/emergency assessment was significantly lower in the blood ketone group (38/100 patient-years) compared with the urine ketone group (75/100 patient-years) (P = 0.05). CONCLUSIONS: Blood ketone monitoring during sick days appears acceptable to and preferred by young people with Type 1 diabetes. Routine implementation of blood 3-OHB monitoring for the management of sick days and impending DKA can potentially reduce hospitalization/emergency assessment compared with urine ketone testing and offers potential cost savings.  相似文献   
89.
Objective To observe the effect of electro-acupuncture combined with early rehabilitation on the motor function and expressions of the adhesion molecules CD11b and CD18 in the polymorphonuclear leucocytes (PMN) and monocytes and serum tumor necrosis factor-α (TNF-α) levels in patients with acute cerebral infarction (ACI). Methods A total of 165 ACI patients were randomly divided into control group (group A, n=50), conventional rehabilitation group (group B, n=50) and comprehensive rehabilitation group (group C, n=65). The expressions of CD11b and CD18 in the PMN and monocytes and serum TNF-α levels were determined before and at 1, 2, and 4 weeks after the treatment. Thirty-two healthy subjects were also recruited as the normal control group (group N). The neurological function of the subjects was evaluated by modified Edinburgh-Scandinavia stroke scale (MESSS) and Fugi-Meyer Assessment (FMA), and their activity of daily living (ADL) was assessed using Barthel index (BI). Results The CD11b/CD18 expression in the PMN and MN and serum TNF-α level in groups A, B and C were significantly higher than those in group N before and 1 week after the treatment (P<0.05). CD11b/CD18 expression and serum TNF-α level were significantly lower in groups B and C than in the group A at 1 week after the treatment, and significantly lower in group C than in group B (P<0.05). At 2 weeks of treatment, CD11b/CD18 and TNF-α were significantly lower in groups B and C than in the group A, being the lowest in group C (P<0.05). The scores of mESSS in both groups B and C were lower than that in group A, and the scores were lower in group C than in group B. Group C showed higher FMA scores than group B, both having higher scores than group A. At 4 weeks of treatment, the mESSS scores were significantly lower, hut the FMA and ADL score significantly higher in groups B and C than in the control group (P<0.05), and the differences were more obvious in group C. Groups B and C had greater effective rate than group A (P<0.05), and the rate was the highest in group C (P<0.05). Conclusion Electro-acupuncture combined with early rehabilitation promotes the recovery of motor function in ACI patients probably by regulating the expressions of the adhesion molecules CD11b and CD18 on the PMN and monocytes and the serum levels of TNF-α.  相似文献   
90.
目的:探讨PHILIPSGyroscanIntera1.5TMRI成像仪正常腹部实质脏器表观弥散系数(ADC)值范围并研究适合本扫描仪腹部弥散加权成像的最佳b值。材料和方法:对30例健康志愿者行磁共振弥散加权成像。在ADC图上直接测量ADC值。结果:所有检查均一次成功得到弥散加权成像(DWI)和ADC图。正常肝脏、胰腺、肾脏、脾脏在b值分别为300、1000、1500s/mm2时的ADC值分别为(10-3mm2/s)1.520±0.169、1.937±0.370、2.632±0.258、1.163±0.188,1.200±0.132、1.484±0.272、2.016±0.178、0.840±0.117,1.068±0.118、1.321±0.149、1.659±0.169、0.747±0.102。不同b值时同一脏器ADC值有统计学差异;四种实质性脏器在同一b值时ADC值有统计学差异。结论:正常腹部不同脏器的ADC值有明显差异。腹部弥散加权成像的b值为300s/mm2和1000s/mm2时,DWI和ADC图像可以互相补充。  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