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   37960篇
  免费   2298篇
  国内免费   160篇
耳鼻咽喉   526篇
儿科学   970篇
妇产科学   663篇
基础医学   4546篇
口腔科学   748篇
临床医学   3608篇
内科学   8914篇
皮肤病学   600篇
神经病学   3551篇
特种医学   1517篇
外国民族医学   1篇
外科学   6476篇
综合类   229篇
一般理论   19篇
预防医学   2379篇
眼科学   497篇
药学   2170篇
中国医学   47篇
肿瘤学   2957篇
  2024年   26篇
  2023年   215篇
  2022年   410篇
  2021年   920篇
  2020年   565篇
  2019年   915篇
  2018年   1145篇
  2017年   804篇
  2016年   809篇
  2015年   969篇
  2014年   1432篇
  2013年   1906篇
  2012年   2810篇
  2011年   3001篇
  2010年   1720篇
  2009年   1650篇
  2008年   2612篇
  2007年   2748篇
  2006年   2576篇
  2005年   2477篇
  2004年   2260篇
  2003年   2086篇
  2002年   1889篇
  2001年   356篇
  2000年   247篇
  1999年   299篇
  1998年   424篇
  1997年   337篇
  1996年   253篇
  1995年   244篇
  1994年   207篇
  1993年   202篇
  1992年   160篇
  1991年   181篇
  1990年   147篇
  1989年   137篇
  1988年   114篇
  1987年   103篇
  1986年   95篇
  1985年   107篇
  1984年   114篇
  1983年   108篇
  1982年   99篇
  1981年   92篇
  1980年   81篇
  1979年   46篇
  1978年   43篇
  1977年   32篇
  1975年   36篇
  1974年   32篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
A 66-year-old man with atrial fibrillation was referred soon after developing left lower limb and abdominal pain with rectal bleeding. An immediate flush aortogram showed embolic occlusion of the left distal superficial femoral artery and superior mesenteric artery (SMA), 3 cm from its ostium. Recombinant tissue plasminogen activitor (rtPA) 40 mg was selectively in stilled in the SMA in two boluses. Abdominal symptoms resolved within 48 h, and complete recanalization of the SMA was shown on angiography. Exploratory laparotomy after 72 h showed a normal small bowel and right colon, and was completed by femoropopliteal embolectomy. Six months later, the patient remained asymptomatic.  相似文献   
42.
43.
44.
Summary It has been suggested that age changes in the morphology of the neuromuscular junction (NMJ) may reflect altered physical activity levels rather than the unique effects of ageing. Additionally, previous studies have indicated that the structure of the NMJ may be modulated with exercise. To investigate these questions, quantitative morphometry was determined on soleus and extensor digitorum longus (EDL) nerve terminals stained with zinc iodide-osmium from C57BL/6NNia mice under control and endurance exercised conditions at 12, 18 and 24 months of age.As previously observed, the area, perimeter, extent length and branch number of nerve terminals increased with age in both soleus and EDL. The changes were similar between the muscle types, although the changes were more pronounced in the phasic EDL. In 12-month-old animals, 2 months of endurance exercise resulted in significantly larger nerve terminals in both soleus and EDL, suggesting a functional adaptation. Exercised 18- and 24-month-old nerve terminals were smaller than corresponding controls, which indicated that exercise minimized or prevented further age-related nerve terminal elaboration. At all ages the exercised nerve terminals comprised a more homogeneous population than corresponding controls, which indicates that uniform physical activity can modulate NMJ morphometry. The magnitude of the changes suggests that subtle alterations in normal cage activity with advancing age do not have a significant effect on the morphology of nerve terminals. However, the morphology of the NMJ does change significantly in response to physical exercise training.  相似文献   
45.
Reactions to Alcohol in Sons of Alcoholics and Controls   总被引:3,自引:0,他引:3  
This paper synthesizes some major findings coming from our laboratory over the last decade. The data focuses on our search for mechanisms that might contribute to the elevated risk for alcoholism in sons of alcoholic fathers. Consistent results corroborated by several additional groups indicate that the higher risk sons of alcoholics demonstrate less intense reactions to ethanol as measured by their subjective self-reports, measures of body sway, changes in several hormones after drinking, and the intensity or persistence of ethanol-related changes on two electrophysiological measures. The potential implications of these results as they might relate to an enhanced vulnerability to alcoholism, and some possible future research directions, are discussed.  相似文献   
46.
OBJECTIVE: Non-steroidal anti-inflammatory drugs (NSAIDs) are routinely used after coronary artery bypass surgery (CABG), yet their effects have seldom been evaluated in randomized controlled settings. The aim of this study was to examine the efficacy and safety of a commonly used NSAID, naproxen. We hypothesized that naproxen would reduce postoperative pain following CABG without increasing complications. METHODS: Patients (N=98) undergoing primary CABG were randomized to receive naproxen (500 mg q12hX5 doses via suppository started 1h after operation, followed by oral 250 mg q8hX6 doses) or placebo. Standard analgesic and anti-emetic regimens were available to both patient groups. Interventions were double-blinded. Primary end-points were postoperative pain measured before and after chest physiotherapy by visual analog scale and pulmonary slow vital capacity (SVC). RESULTS: Baseline characteristics were equivalent between the two groups. Over the first 4 postoperative days, naproxen decreased pain by 47+/-17% on average before chest physiotherapy (P=0.034), and 44+/-13% after chest physiotherapy (P=0.0092). Patients who received naproxen also had better preservation of SVC over the first 4 postoperative days (mean loss of SVC from baseline: 2.1+/-0.1 vs. 2.5+/-0.1l, naproxen vs. placebo, P=0.0032). This was concomitant with a lower white blood cell count observed in naproxen patients (9.2+/-0.3 vs. 12.7+/-1.5x10(9)/l, naproxen vs. placebo, P=0.03). Patients who received naproxen had more chest tube drainage after 4h postoperatively, but there was no difference in the incidence or amount of transfusions. There was no difference in medication use, length of stay, or in the incidence of atrial fibrillation, azotemia, and other complications. CONCLUSIONS: Naproxen is an effective and low-cost adjunct for optimization of pain control and lung recovery after CABG. Its use may result in increased chest tube drainage, but no apparent increase in other complications.  相似文献   
47.
PURPOSE: The gum elastic bougie (GEB) has been in use for a long time and allows tracheal intubation in most cases of difficult direct laryngoscopy. Use of the GEB when anatomical landmarks of the upper airway are not recognizable has not been reported. We describe our experience of airway management with the GEB in cases of severe upper airway distortion. CLINICAL FEATURES: Four patients with severe respiratory distress caused by upper airway distortion secondary to various non-malignant causes were managed with the GEB. For these four patients, a rapid sequence induction of anesthesia was performed with a surgeon present during the procedure. The GEB was used as the initial intubating technique in all cases and allowed a rapid and successful tracheal intubation in spite of non-recognizable anatomical structures. The distal hold-up feeling after GEB insertion confirmed, in all cases, the correct intratracheal position of the GEB. CONCLUSION: The GEB can be a valuable tool in cases of difficult airway management caused by upper airway distortion. The lack of visualization of normal pharyngeal structures did not prevent the successful insertion of the GEB in the trachea in the four patients reported.  相似文献   
48.
The objective of this article is to summarize the diagnostic criteria recommended by the International Panel on the Diagnosis of Multiple Sclerosis in 2001. The recommendations of another working group, the Consortium of Multiple Sclerosis Centers Consensus Meeting, which met in Vancouver in 2001, concerning the diagnosis and follow-up of patients with multiple sclerosis are also presented in an effort to standardize the protocols for magnetic resonance imaging of these patients.  相似文献   
49.
BACKGROUND: Residual blood flow around thrombus prior to treatment predicts success of coronary thrombolysis. The authors aimed to correlate the presence of residual flow signals in the middle cerebral artery (MCA) with completeness of recanalization after intravenous tissue plasminogen activator (TPA). METHODS: The authors studied consecutive patients treated with intravenous TPA therapy who had a proximal MCA occlusion on pretreatment transcranial Doppler (TCD). Patients were continuously monitored for 2 hours after TPA bolus. Absent residual flow signals correspond to the thrombolysis in brain ischemia (TIBI) 0 grade, and the presence of residual flow signals was determined as TIBI 1-3 flow grades. Complete recanalization was defined as flow improvement to TIBI grades 4-5. RESULTS: Seventy-five patients with a proximal MCA occlusion had median pre-bolus NIHSS 16 (85% with > or = 10 points). TPA bolus was given at 141 +/- 56 minutes (median 120 minutes). Complete recanalization was observed in 25 (33%), partial in 23 (31%), and no early recanalization was seen in 27 (36%) patients within 2 hours after TPA bolus. Only 19% with absent residual flow signals (TIBI grade 0, n = 26) on pretreatment TCD had complete early recanalization. If pretreatment TCD showed the presence of any residual flow (TIBI 1-3, n = 49), 41% had complete recanalization within 2 hours of TPA bolus (P = .03). CONCLUSIONS: Patients with detectable residual flow signals before IV TPA bolus are twice as likely to have early complete recanalization. Those with no detectable residual flow signals have less than 20% chance for complete early recanalization with intravenous TPA and may be candidates for intra-arterial therapies.  相似文献   
50.
Stones in caliceal diverticula may cause symptoms for which treatment is indicated. Both extracorporeal shock wave lithotripsy (ESWL) and percutaneous nephrolitholapaxy (PNL) are recommended. We have evaluated the results of ESWL treatment of stone-containing caliceal diverticula and compared these with the results obtained by percutaneous surgery. In the ESWL group, 15 patients were treated with an electromagnetic lithotriptor (Siemens Lithostar). After 3 months, plain abdominal X-rays revealed that only 2 patients were both stone-free and symptom-free. Of the 13 patients with residual fragments, 7 had no symptoms. The remaining 6 were treated by a lower pole resection (n = 3), a percutaneous procedure (n = 2) and long-term administration of antibiotics (n = 1). Sixteen patients were treated percutaneously. Puncture failed in 3 and they underwent a lumbotomy. In the remaining 13 patients the stones were reached by direct puncture (n = 12) or via an adjacent calix (n = 1). After 3 months, 10 patients were stone-free and had no symptoms. Morbidity consisted of post-operative bleeding (n = 3) and high fever (n = 1). It was concluded that caution should be exercised in the treatment of stone-containing caliceal diverticula. Only in symptomatic cases is treatment indicated and ESWL is the first choice. If ESWL fails (residual stones and persistent symptoms), PNL should be performed, although it is associated with a higher morbidity rate.  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