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   18469篇
  免费   1031篇
  国内免费   47篇
耳鼻咽喉   176篇
儿科学   493篇
妇产科学   789篇
基础医学   2431篇
口腔科学   486篇
临床医学   1610篇
内科学   3658篇
皮肤病学   409篇
神经病学   1983篇
特种医学   944篇
外国民族医学   3篇
外科学   2658篇
综合类   132篇
一般理论   38篇
预防医学   1177篇
眼科学   222篇
药学   1191篇
中国医学   25篇
肿瘤学   1122篇
  2021年   215篇
  2020年   157篇
  2019年   227篇
  2018年   315篇
  2017年   221篇
  2016年   275篇
  2015年   299篇
  2014年   463篇
  2013年   588篇
  2012年   907篇
  2011年   959篇
  2010年   489篇
  2009年   502篇
  2008年   719篇
  2007年   828篇
  2006年   925篇
  2005年   804篇
  2004年   730篇
  2003年   770篇
  2002年   722篇
  2001年   673篇
  2000年   700篇
  1999年   502篇
  1998年   259篇
  1997年   221篇
  1996年   132篇
  1995年   138篇
  1993年   148篇
  1992年   355篇
  1991年   314篇
  1990年   344篇
  1989年   330篇
  1988年   298篇
  1987年   304篇
  1986年   283篇
  1985年   257篇
  1984年   178篇
  1983年   165篇
  1982年   110篇
  1979年   203篇
  1978年   122篇
  1977年   118篇
  1976年   119篇
  1975年   162篇
  1974年   170篇
  1973年   147篇
  1972年   148篇
  1971年   120篇
  1970年   138篇
  1969年   108篇
排序方式: 共有10000条查询结果,搜索用时 843 毫秒
71.
ELISA-based epitope analysis was performed using rabbit polyclonal antisera against melittin. Antigenic sites were found at the C-terminus, in the middle section and within the N-terminal helix. Antibodies against the helical segment could discriminate between two faces of the amphiphilic helix. The antigenic sites include the bulk of the melittin hexacosapeptide, which is synonymous with a very high epitope density.  相似文献   
72.
73.
In the neonatal period ultrasound and hepatobiliary functional scintigraphy are used to diagnose choledochal cysts. Initial sonography demonstrates hepatobiliary anatomy, hepatobiliary function is assessed by subsequent scintigraphy. The diagnosis can be confirmed by additional computed tomography as shown in this case report.  相似文献   
74.
Prostaglandin E1 (PGE1) is widely used in neonates with cyanotic congenital heart disease who depend on the patency of the ductus arteriosus for oxygenation. Side effects of prostaglandin therapy are common and include respiratory depression, generalized flushing, and cardiovascular and neurological effects. Little is known about the complex effects on the gastrointestinal tract. We report on an infant with gastric outlet obstruction after long-term prostaglandin administration. At the age of 1 month, feeding problems developed with projectile vomiting. Ultrasonography showed progressive elongation of the antropyloric channel without wall thickening, which was causing gastric outlet obstruction. Three days after cardiac surgery and cessation of prostaglandin therapy, the infant fed normally and rapidly gained weight. The clinical signs in such patients can mimic hypertrophic pyloric stenosis. Therefore, the sonographic findings should not be confused with pyloric wall thickening to avoid a false diagnosis and unnecessary surgery. The symptoms diminish with cessation of the prostaglandin therapy after a corrective cardiac operation.  相似文献   
75.
Intraabdominal pressures were measured during natural activities in 6 men, age 24-62 years, treated with continuous ambulatory peritoneal dialysis. The pressures were measured with a pressure transducer secured at the level of the umbilicus in the supine, sitting, and upright positions with 0-3 liters intraperitoneal fluid during talking, coughing, straining, changing position, walking, jogging, exercycling, jumping and weight lifting. Coughing and straining generated the highest intraabdominal pressures in every position. The pressures with weight lifting were proportional to the magnitude of the weight lifted up to 50 lbs, but were lower than those during coughing and straining. The pressures were generally higher with greater intraabdominal fluid volumes, especially with jumping and coughing. Exercycling was associated with lower intraabdominal pressure than was jogging, and the pressures were only minimally influenced by intraperitoneal fluid volumes. The results of this study can be used as a guide in establishing preventive measures in patients with intraperitoneal fluid to decrease complication rates related to raised intraabdominal pressures such as dialysate leaks, hernias and hemorrhoids.  相似文献   
76.
A total of 178 patients with metastatic renal cell cancer were randomized to receive interferon alfa-2a (rIFN alfa-2a) or interferon alfa-2a+vinblastine (VLB). IFN alfa-2a was injected intramuscularly at a dose of 18 MIU 3 times a week and VLB was given intravenously at a dose of 0.1 mg/kg once every 3 weeks. The response rate was 11% for patients on monotherapy and 24% for those on combination treatment. The 5-year survival for 145 eligible patients was 9%, independently from the treatment arm. The performance status was significantly related to long-term prognosis, and 13% of the patients with performance status 0 were alive at 5 years, as compared to 6% and 0% for patients with a WHO grade of 1 and 2, respectively. The most frequent adverse events in both treatment arms were flu-like symptoms (95%), fatigue (70%) and gastrointestinal disturbances (68%). Leukopenia was observed more frequently with combination treatment (53%) than with IFN alfa-2a alone (30%). In conclusion, rIFN alfa-2a monotherapy at this dose and schedule has modest antitumor activity in metastatic renal cell cancer. The combination of rIFN alfa-2a+VLB results in a doubling of the response rate, but this does not translate into prolonged survival. Toxicity (except leukopenia) and tolerance were similar in both treatment arms.  相似文献   
77.
The non-invasive measurement of the extremely weak magnetic fields generated by heart and brain is motivated by the possibility of obtaining quantitative diagnostic information about electric function. Magnetic signals (MCG, MEG) are significantly less influenced by body tissue than the corresponding electric signals (ECG, EEG). Measurement of biomagnetic signals is performed by superconducting sensors, consisting of pickup coils and SQUIDs (superconducting quantum interference device) operating in liquid Helium. For clinical investigations a biomagnetic multi-channel system (KRENIKONR) has been designed. It uses a flat array of 37 magnetic field sensors and is operated inside a shielded room. Evaluation of biomagnetic signals by use of simple source and body models and in combination with anatomical data from 3D MR- or CT-images yields sequences of locations of electrical function with a spatial resolution of some millimeters and a time resolution better than one millisecond. More than three years of clinical studies have demonstrated the value of the method primarily in cases with localized functional pathologies. In cardiology this is pathologies of the cardiac conductive pathway, ectopies, and arrhythmias. Validation has been performed by catheter stimulation in volunteers, and by catheter mapping and nuclear medical methods in patients. Extension of modelling and evaluation to cases with distributed activity, e.g. ventricular excitation, is under investigation.  相似文献   
78.
79.
This study was devised to identify sepsis-relevant parameters that early and reliably predict a lethal outcome in intra-abdominal sepsis. In 18 Duroc pigs, peritonitis was induced through standardized gastrotomy. Twelve hours later the defect was oversewn and the abdominal cavity lavaged thoroughly. Sepsis relevant parameters were measured before initiating therapy, and 30 min later animals were extubated and observed for a period of 6 days under adequate analgesia with free access to water and food. All parameters were correlated with survival postoperatively. In the treatment group, 7 out of 18 pigs (39%) died within the observation period. Endotoxin level at 30 min after initiation of therapy [17.9 EU/mL (+/- 12.1) vs. 110.9 EU/mL (+/- 21); p <.001] and Delta pHi [0.015 (+/- 0.011) vs. -0.039 (+/- 0.013); p =.016] were identified as the two parameters with highest predictive power regarding mortality in a multivariate analysis. In conclusion measurement of endotoxin and gastric tonometry should gain wider clinical application in septic patients.  相似文献   
80.
Zusammenfassung. Mit dem Ziel, die Incidenz tiefer Venenthrombosen bei selektierten Patienten nach laparoskopischer Cholecystektomie und anderen minimal-invasiven chirurgischen Eingriffen zu bestimmen, sowie die Sicherheit und Wirksamkeit eines niedermolekularen Heparinpr?parats (NMH) in der postoperativen Thromboseprophylaxe zu belegen, wurde eine prospektive, randomisierte, kontrollierte klinische Studie durchgeführt. Dabei wurden 718 Patienten nach Randomplan einer von 2 Prüfgruppen zugeordnet: Eine Gruppe erhielt physikalische Ma?nahmen zur Thromboseprophylaxe, wie Kompressionsstrümpfe mit graduiertem Andruck (n = 359), die 2. Gruppe erhielt ebenfalls physikalische Ma?nahmen und zus?tzlich ein NMH (Reviparin-Natrium, Clivarin) s. c. einmal t?glich (n = 359). Aus Sicherheitsgründen mit Hinblick auf die medikament?s unbehandelte Kontrollgruppe wurden Patienten mit 3 oder mehr Risikofaktoren für eine ven?se Thromboembolie nicht in die Studie aufgenommen. Die Diagnostik tiefer Beinvenenthrombosen erfolgte mittels Duplexscan. In dieser, eher künstlichen Niedrigrisikoselektion war die Gesamtincidenz thromboembolischer Ereignisse überraschend gering: 5 Verdachtsf?lle einer Lungenembolie, von denen nur 1 Lungenembolie szintigraphisch verifiziert werden konnte, sowie eine phlebographisch best?tigte Unterschenkelthrombose. Die Anwendung von Reviparin zur Prophylaxe ven?ser Thromboembolien war sicher und anwenderfreundlich – die Incidenz postoperativer Blutungskomplikationen betrug nur 2,3 % in der NMH-Gruppe und war somit sogar geringfügig niedriger als in der Kontrollgruppe (3,2 %). Die tats?chliche Incidenz tiefer Venenthrombosen bei Patienten nach laparoskopischer Cholecystektomie bleibt jedoch nach wie vor unklar. Weitere klinische Studien müssen in einem unselektierten Patientengut durchgeführt werden.   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