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   17008篇
  免费   893篇
  国内免费   54篇
耳鼻咽喉   328篇
儿科学   365篇
妇产科学   389篇
基础医学   2678篇
口腔科学   420篇
临床医学   1381篇
内科学   3089篇
皮肤病学   337篇
神经病学   1665篇
特种医学   1276篇
外国民族医学   5篇
外科学   2484篇
综合类   94篇
一般理论   4篇
预防医学   888篇
眼科学   325篇
药学   1225篇
中国医学   28篇
肿瘤学   974篇
  2022年   128篇
  2021年   232篇
  2020年   155篇
  2019年   218篇
  2018年   266篇
  2017年   205篇
  2016年   298篇
  2015年   357篇
  2014年   447篇
  2013年   562篇
  2012年   900篇
  2011年   940篇
  2010年   611篇
  2009年   628篇
  2008年   947篇
  2007年   995篇
  2006年   1025篇
  2005年   1055篇
  2004年   943篇
  2003年   912篇
  2002年   858篇
  2001年   399篇
  2000年   435篇
  1999年   383篇
  1998年   224篇
  1997年   165篇
  1996年   152篇
  1995年   140篇
  1994年   121篇
  1993年   103篇
  1992年   181篇
  1991年   168篇
  1990年   176篇
  1989年   174篇
  1988年   122篇
  1987年   158篇
  1986年   132篇
  1985年   127篇
  1984年   108篇
  1983年   79篇
  1982年   76篇
  1979年   119篇
  1978年   77篇
  1977年   91篇
  1976年   70篇
  1975年   89篇
  1974年   98篇
  1973年   90篇
  1972年   77篇
  1969年   74篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
To date microscopy and cultural isolation still remain the “gold standard” in the laboratory diagnostics of mycobacteria. Nucleic acid amplification techniques additionally enable a rapid and sensitive detection of Mycobacterium tuberculosis. However, bacterial growth is still required for species identification and susceptibility testing which should be performed from one of the first isolates of every patient and repeated after about 2 months if cultures are still positive. By means of DNA fingerprint techniques, the confirmation of transmission, of TB outbreaks, and also of laboratory cross-contamination is feasible.  相似文献   
32.
We evaluated the role of thallium-201 single-photon emission-computed tomography (SPECT) in diagnosis, differential diagnosis and follow-up of 33 patients with primary brain tumors. 27 of 33 lesions were detectable by Tl-201 SPECT because only two of eight low-grade (grade 1 and 2) astrocytomas showed Tl-201 accumulation up to a tumor to nontumor ratio of 2.6. High grade (grade 3 and 4) astrocytomas showed Tl-201 accumulation in the range of 2.2 up to 13.0 and were different from low-grade astrocytomas. Noninvasive grading of astrocytomas is therefore possible, whereas differential diagnosis of oligodendrogliomas and astrocytomas or meningiomas was not possible with Tl-201. In the follow-up of six patients, we could demonstrate, that tumor progression is correlated with increasing and tumor regression with decreasing Tl-201 accumulations. This functional changing proceed morphological findings in CT. But vanishing of Tl-201 accumulation during therapy does not mean vanishing of tumor as could be demonstrated by follow-up.  相似文献   
33.
The following article presents two new cases of a lipofibroma of the median nerve. This formation is a very rare benign tumor of peripheral nerve tissue. Up to now 30 cases have been reported in the literature and are reviewed in this article and are compared with the two cases reported. Besides the operative treatment, which made the neuropathological diagnosis possible, preoperative diagnosis has been extended by MNT-scans of the involved parts of the nerve. The noninfiltrating character of the tumor could be well recognized on these scans. The signal quality and the anatomical proximity to the median nerve made the diagnosis of a lipofibroma likely. By the postoperative histological reviews the diagnosis was confirmed in classic manner. The immunological marking of the S-100 protein showed a remarkable reduction of this protein in these peripheral nerve tumors. The two cases reported by us recapitulate the clinical history typically and describe symptoms and our treatment for the lipofibroma of the median nerve.  相似文献   
34.
We evaluated the function of the supraspinatus tendon with a dynamic shoulder model. Active glenohumeral joint motion was simulated in 10 cadaveric shoulder specimens with hydrodynamic cylinder forces at the deltoid muscle and at the rotator cuff. Computerized regulation initiated standardized cycles of glenohumeral joint motion, where the isolated effect of the supraspinatus muscle could be studied. The efficacy of the supraspinatus muscle on elevation of the glenohumeral joint was measured with an ultrasonic sensor system. Pressures underneath the coracoa-cromial vault were recorded with capacitive sensors, as an indicator of the impingement at the shoulder. Elimination of force of the supraspinatus muscle led to a 6 percent decrease in elevation of the glenohumeral joint. The deltoid muscle was able to reverse this loss of elevation by a force increase of one third of the lost supraspinatus force. If no force was applied to the supraspinatus muscle, average pressures underneath the coracoacromial vault decreased 8 percent. It was concluded that the supraspinatus produces less torque and more glenohumeral joint compression than the deltoid. However, the supraspinatus has no effect on depression of the humeral head during elevation.

The clinical consequence of our observations is that operative closure of supraspinatus tendon defects is not mandatory.  相似文献   
35.
The Changing Faces of the Nutcracker Esophagus   总被引:3,自引:0,他引:3  
Although the nutcracker esophagus, characterized by high amplitude peristaltic contractions with mean distal amplitude greater than 180 mm Hg, is the most common esophageal motility disorder associated with noncardiac chest pain, little is known about its natural history. Therefore, we reviewed the manometric tracings of 23 patients with the nutcracker esophagus who had an average of 4.6 studies during a mean period of 32 months. Ten age-matched volunteers with normal baseline manometry who had undergone multiple studies (mean 5.8) over a mean time span of 32 months served as controls. In the 17 nutcracker patients with three or more motility studies, the variability of mean distal amplitudes between studies was 41.9% +/- 4.1 (+/- SE) compared to 27.0% +/- 3.3 for the control subjects (p less than 0.01). Highest distal pressures were noted during the first study in 11 of 17 patients (65%) compared to two of 10 controls (20%). The consistency of the diagnosis of nutcracker esophagus varied considerably: four patients always had high amplitude pressures, three patients only had the nutcracker diagnosis on the initial study, and 10 patients intermittently had pressures in the nutcracker range. Overall, these 17 patients had the diagnosis of the nutcracker esophagus confirmed on only 54% of subsequent studies. Changes in motility patterns were intermittently seen in six of 23 patients: one diffuse spasm and five nonspecific motility disorders. None of the control subjects developed high amplitude contractions or changed their motility pattern on serial testing. The possible pathophysiological implications of the changing faces of the nutcracker esophagus are discussed.  相似文献   
36.
37.
An increasing number of patients desire body contouring surgery after massive weight loss, whether from bariatric surgery or a change in lifestyle. The fact that many body regions lose their elasticity and tissue-tension has led to stepwise treatments including abdominoplasty, thigh lift, buttocks and hip lift or liposuction. However, these procedures often do not treat the reason for the deformities. The lower body lift first described by Ted Lockwood in 1993 is a procedure that allows simultaneous skin resection and tightening of different regions including the abdomen, buttocks, hips, and thighs. In this article the authors present their 10-year experience with the body lift. Patient selection, technical details, pre- and postoperative care, complications, and expected results are all discussed.  相似文献   
38.
Zusammenfassung Der richtige Zeitpunkt für das Absetzen der Antiepileptika (AE) im Kindesalter ist unbekannt. Anl?sslich ihrer Jahrestagung haben die Mitglieder des K?nigsteiner Arbeitskreises (KA) eigene und publizierte Absetzstrategien diskutiert. Da Studien zu diesem Thema rar und widersprüchlich sind, wurde beschlossen, die Diskussionsergebnisse im Sinne einer Meinungs?u?erung zu publizieren. Bei Neugeborenen besteht übereinstimmung, AE innerhalb von 2 bis 12 Wochen nach dem letzten Anfall abzusetzen. Bei BNS-Epilepsie wird Vigabatrin nach 6 bis 12 und Sultiam nach 6 bis 36 Monaten abgesetzt. Nach erfolgreicher Steroidtherapie setzt die Mehrheit des KA die AE-Therapie für zwei Jahre fort. Für die Rolando-Epilepsie sind 1 bis 3 Jahre Anfallsfreiheit ausreichend, auch wenn fokale Spike-Waves persistieren. Im Falle einer symptomatisch fokalen Epilepsie ist die Grunderkrankung mitentscheidend für das Absetzen. Die Behandlung der Absencen-Epilepsie kann nach zwei Jahren beendet werden, w?hrend bei myoklonisch- astatischer Epilepsie meist eine 2- bis 5-j?hrige Anfallsfreiheit vorausgesetzt wird. Konsens besteht darüber, dass die Juvenile- Myoklonus-Epilepsie ein sehr hohes Rückfallrisiko birgt. Dennoch ziehen einzelne neurop?diatrische Mitglieder einen Absetzversuch nach 2- bis 3-j?hriger Anfallsfreiheit in Betracht. Die überwiegende Mehrheit des KA führt aber bei gesicherter Diagnose keinen Absetzversuch durch. Bezüglich der Absetzgeschwindigkeit wird ein langsames (3 bis 12 Monate) Ausschleichen favorisiert. Nur zwei Mitglieder praktizieren ein rascheres Absetzen (<3 Monaten). Das EEG spielt für die Entscheidung eine untergeordnete Rolle und bleibt auf bestimmte Epilepsieformen (z. B. Absencen-Epilepsie) beschr?nkt. Das vorliegende Papier gibt die Meinung des KA wieder und eignet sich nicht im Sinne einer Leitlinie. Für die Entscheidung AE abzusetzen, ist immer eine individuelle Abw?gung von Grunderkrankung, Epilepsieform und psychosozialen Umst?nde erforderlich.   相似文献   
39.
The dissolution rate of the model drugs carbamazepine and nifedipine was improved by adsorbing solutions of the drugs in hydrophilic non-volatile or volatile solvents onto carriers with a large surface area. This was accomplished by dissolving the drug in methanol or the non-toxic hydrophilic liquids PEG 400 or 2-pyrrolidone, and adsorbing these solutions onto the surface of silica (Aerosil) or crosslinked polyvinylpyrrolidone (Kollidon CL-M). The solvent binding capacities decreased in the order of methanol, PEG 400, 2-pyrrolidone for Aerosil 200, 300, 380 and for Kollidon CL-M. Kollidon bound less liquid than Aerosil because of the smaller surface area. Differential scanning calorimetry measurements showed higher interactions between drugs and Kollidon compared to Aerosil, suggesting a low aggregation of precipitated drug particles. The drug release from the adsorbent systems was enhanced when compared to micronized drug and independent of the drug loading in the investigated range. The drugs were also dissolved in various liquid, paste-like or solid solubilisers (polyoxyl-40-hydrogenated castor oil (Cremophor RH 40), macrogol-15-hydroxystearate (Solutol HS), poloxamers (Lutrol F68, Pluronic F87NF and Pluronic L44NF) and adsorbed onto Kollidon. These adsorbent systems also exhibited an increased dissolution rate when compared to pure drug.  相似文献   
40.
Introduction Failure to enter the coronary sinus (CS) with a guiding catheter and entering its tributaries remains challenging in left ventricle (LV) pacing lead implants for cardiac resynchronization therapy (CRT). A dual telescoping catheter system (8F outer/6F inner) is designed to provide the ability to adjust the catheter curve size, shape and/or reach to the patients’ anatomy avoiding the need for catheter change. Methods Five different designs for CS cannulation were randomly tested in 64 patients scheduled for CRT device implant. Results In 33 consecutive patients three adaptable telescoping guiding catheter systems were tested per patient, the adaptable catheters had higher overall cannulation success rates (68, 63 and 62%) compared to the fixed shape catheter (46%) and an greater cannulation success rate when the CS location was not known (70, 53 and 72% vs 33% for the fixed shape). In a second group of 31 CRT patients the two telescoping catheters had similar high levels of success (71–80%), with or without using the inner catheter. Conclusions The telescopic system is adaptable to a wide range of anatomical variations in patients and can result in a higher CS cannulation success rate due to its adjustability in the RA in search for the CS ostium. On top of this the inner catheter allows for sub-selecting the CS tributaries.  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