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   26910篇
  免费   1227篇
  国内免费   68篇
耳鼻咽喉   363篇
儿科学   841篇
妇产科学   657篇
基础医学   3493篇
口腔科学   793篇
临床医学   2116篇
内科学   4835篇
皮肤病学   518篇
神经病学   2433篇
特种医学   939篇
外国民族医学   1篇
外科学   4032篇
综合类   89篇
一般理论   8篇
预防医学   2912篇
眼科学   582篇
药学   1911篇
中国医学   90篇
肿瘤学   1592篇
  2023年   173篇
  2022年   214篇
  2021年   448篇
  2020年   304篇
  2019年   391篇
  2018年   628篇
  2017年   511篇
  2016年   608篇
  2015年   665篇
  2014年   738篇
  2013年   1054篇
  2012年   1481篇
  2011年   1655篇
  2010年   853篇
  2009年   688篇
  2008年   1180篇
  2007年   1377篇
  2006年   1209篇
  2005年   1299篇
  2004年   1268篇
  2003年   1209篇
  2002年   1107篇
  2001年   658篇
  2000年   679篇
  1999年   578篇
  1998年   190篇
  1997年   168篇
  1996年   141篇
  1992年   353篇
  1991年   324篇
  1990年   348篇
  1989年   326篇
  1988年   307篇
  1987年   296篇
  1986年   317篇
  1985年   317篇
  1984年   245篇
  1983年   211篇
  1979年   247篇
  1978年   164篇
  1975年   157篇
  1974年   198篇
  1973年   199篇
  1972年   212篇
  1971年   175篇
  1970年   151篇
  1969年   194篇
  1968年   169篇
  1967年   159篇
  1966年   144篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
Authors present a method of esophageal dilatation and report their experiences. The place of esophageal dilatation among other therapeutic approaches of esophageal stricture is discussed. The advantage of Savary-Gilliard bougies and guide wire and its applications are presented. During one and a half year 218 esophageal dilatations were performed at 82 patients. 11 patients were intubated endoscopically. Esophageal perforation occurred in 2 cases (0.93%). Dilatation of the esophagus with Savary-Gilliard bougies and using of the guide wire are considered a safe and many-sided method in the diagnosis and treatment of esophageal strictures.  相似文献   
82.
Medical records of 170 patients who had undergone thymectomy for myasthenia gravis were reviewed from the point of view of respiratory disturbances. In the group of patients requiring mechanical ventilation for over 24 hours after operation the incidence of high preoperative cholinesterase inhibitor intake, severe bulbar symptoms and severe myasthenia gravis with anamnestic respiratory crisis and cardiorespiratory disease were much higher than in the group of patients who could have their trachea extubation within 24 hours. The presence of a thymic tumour, patients' age over 50 years and the so-called precrisis have revealed differences between the two groups, while the patient groups were identical in mean age, duration of myasthenia gravis and sex distribution. The above clinical data are recommended to be considered in the evaluation of the need for postoperative mechanical ventilation or extubation and preparation of preventive tracheotomy.  相似文献   
83.
This study was performed to examine the pattern of Superoxide (O 2 ·) generation from leukocytes using the O 2 · specific chemiluminescence (CL) method.Cypridina luciferin analog, 2-methyl-6-(p-methoxyphenyl)-3,7-dihydroimidazo[1,2-alpha]pyrazin-3-one (MCLA) was used as a CL probe. The appropriate conditions of the MCLA method was first determined for the evaluation of the time course of O 2 · generation by leukocytes. The time course of O 2 · generation obtained by the MCLA-CL system was compared with that by the luminol-dependent CL, electron spin resonance (ESR)/spin trapping, and cytochromec systems. Following stimulation by three different stimulants (PMA, OZ, FMLP), leukocytes continuously generated O 2 · for up to 5 h in the MCLA-CL system, irrespective of the kind of stimulation. The curves obtained by generation ceased more rapidly in the luminol-CL, ESR/spin trapping, and cytochromec systems. A 50% activity of the initial value was observed at 70 min in the MCLA-CL system, but 30, 10 and 35 min in the other systems, respectively. The CL or O 2 · generation value decreased to less than 1% (possible termination) at 300, 90, 120 and 180 min, respectively. With the exception of ESR studies with OZ, the cell viability was not significantly affected in any of the trials. These results indicate that leukocytes can generate O 2 · much longer than previously estimated and that the MCLA-CL-system is the most suitable system for the measurement of the O 2 · generation by leukocytes.  相似文献   
84.
85.
The effect of three beta-lactamase inhibitors, clavulanic acid, sulbactam and tazobactam used in clinical practice were compared for their activity against purified beta-lactamases from Bacteroides uniformis, Clostridium butyricum and Fusobacterium nucleatum. The enzymes from B. uniformis and C. butyricum were produced in fermenters under controlled growth conditions and the enzyme from F. nucleatum was produced in batch cultures. Purification of the beta-lactamases was achieved by anion-exchange chromatography, gel filtration and FPLC-technique. The degree of inactivation of beta-lactamase activity was determined spectrophotometrically with nitrocefin as the substrate. The inhibitors in various concentrations were preincubated at 30 degrees C together with the enzyme for different time periods (0.5-120 min) before determination of the remaining beta-lactamase activity. The inhibitors all decreased the activity of the beta-lactamases investigated. Clavulanic acid and sulbactam were capable of reducing the enzyme activity of the B. uniformis beta-lactamase more effectively than the C. butyricum and F. nucleatum beta-lactamases. All beta-lactamases tested were more susceptible to tazobactam than to clavulanic acid and sulbactam.  相似文献   
86.
Visceral hypersensitivity is important in the pathophysiology of irritable bowel syndrome and thus a target for modulation in drug development. Neurokinin (NK) receptors, including NK(3) receptors, are expressed in the motor and sensory systems of the digestive tract. The aim of this study was to compare the effects of two different doses (25 and 100 mg) of the NK(3) receptor antagonist, talnetant (SB223412) with placebo on rectal sensory function and compliance in healthy volunteers studied at two centres. Rectal barostat tests were performed on 102 healthy volunteers, randomized to receive either oral talnetant 25 or 100 mg or placebo over 14-17 days. Studies were performed on three occasions: day 1 immediately prior to 1st dose, day 1 4 h postdose, and after 14- to17-day therapy. Compliance, and pressure thresholds for first sensation, urgency, discomfort and pain were measured using ascending method of limits, and sensory intensity ratings for gas, urgency, discomfort and pain determined during four random phasic distensions (12, 24, 36 and 48 mmHg). Talnetant had no effect on rectal compliance, sensory thresholds or intensity ratings compared with placebo. In general, the results obtained at the two centres differed minimally, with intensity scores at one centre consistently somewhat lower. At the doses tested, talnetant has no effect on rectal compliance or distension-induced rectal sensation in healthy participants.  相似文献   
87.
Prediction of hemorrhagic transformation (HT) in patients treated by intravenous recombinant tissue-type plasminogen activator (rt-PA) is a challenging issue in acute stroke management. HT may be correlated with severe hypoperfusion. Signal changes may be observed at susceptibility-weighted magnetic resonance imaging (MRI) within large perfusion defects. A signal drop within cerebral veins at T2*-weighted gradient-echo MRI may be expected in severe ischemia, and may indicate subsequent risk of HT. The authors prospectively searched for an abnormal visibility of transcerebral veins (AVV) within the ischemic area in patients with hemispheric ischemic stroke, before they were treated with intravenous rt-PA therapy. Any correlation between AVV and baseline clinical or MRI findings, or further HT, was noted. An AVV was present in 23 of 49 patients (obvious, n = 8; moderate, n = 15), and was supported by severe hemodynamic changes at baseline MRI. The AVV was correlated with the occurrence of parenchymal hematoma type 2 at computed tomography during the first week (r = 0.44, P = 0.002). Five of six type 2 parenchymal hematomas occurred in association with obvious AVV. At multiple regression analysis, two baseline MRI factors had an independent predictive value for HT risk during the first week: the AVV and the cerebral blood volume ratio (Nagelkerke R2 = 0.48).  相似文献   
88.
M Gmür 《Psychopathology》1991,24(4):219-224
A sample of 46 schizophrenic patients (26 men and 20 women) from a night clinic (N subjects) with an average age of 21.7 years at the time of first manifestation of the illness and a sample of hospital inpatients (H subjects) matched for diagnosis, sex, and age were followed up from 1971/1973 to 1983. The average age of the patients in 1983 was 40 years. The course of the illness and the pattern of hospitalization were investigated by personally questioning each patient and by scrutinizing all the case history records and other relevant documents; for each clinical cycle of illness, consisting of an overt phase followed by a quiescent interval, a case control sheet was filled out. The duration of illness was 18 years for the N subjects and 15 years for the H subjects. Longitudinal analysis of these years of illness in both patient samples showed a marked decrease in the number and duration of overt phases and stays in hospital, but a progressive aggravation of residual symptomatology during quiescent intervals and a progressively decreasing ability to work and earn a living.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
89.
90.
Intrascrotal adenomatoid tumors   总被引:1,自引:0,他引:1  
Adenomatoid tumors are regarded as uncommon neoplasms of the paratesticular tissues, probably of mesothelial origin. The majority of cases reported have involved the epididymis. We report our experience with 8 cases of testicular tumors and 11 of epididymal adenomatoid tumors during a 13-year period, and review the relevant literature. The incidence of adenomatoid tumors relative to all tumors in the testis was 6.9% (8 of 116), exceeding that of Leydig cell tumors, which were previously believed to be the most common benign testicular neoplasms. The adenomatoid tumors included 38% epididymal tumors (11 of 29). The clinical course of the tumors was benign, without recurrences. Local excision is regarded as the treatment of choice for epididymal and testicular adenomatoid tumors.  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