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   1854篇
  免费   81篇
  国内免费   12篇
耳鼻咽喉   15篇
儿科学   17篇
妇产科学   15篇
基础医学   284篇
口腔科学   55篇
临床医学   119篇
内科学   341篇
皮肤病学   218篇
神经病学   115篇
特种医学   69篇
外科学   343篇
综合类   2篇
一般理论   1篇
预防医学   56篇
眼科学   21篇
药学   173篇
中国医学   1篇
肿瘤学   102篇
  2022年   15篇
  2021年   24篇
  2020年   14篇
  2019年   28篇
  2018年   28篇
  2017年   33篇
  2016年   33篇
  2015年   40篇
  2014年   63篇
  2013年   74篇
  2012年   114篇
  2011年   111篇
  2010年   58篇
  2009年   66篇
  2008年   101篇
  2007年   97篇
  2006年   116篇
  2005年   124篇
  2004年   119篇
  2003年   107篇
  2002年   115篇
  2001年   26篇
  2000年   35篇
  1999年   25篇
  1998年   18篇
  1997年   13篇
  1996年   20篇
  1995年   17篇
  1994年   16篇
  1993年   14篇
  1991年   7篇
  1990年   12篇
  1989年   9篇
  1988年   11篇
  1987年   15篇
  1986年   13篇
  1985年   13篇
  1984年   10篇
  1983年   9篇
  1982年   9篇
  1980年   8篇
  1978年   7篇
  1976年   6篇
  1975年   6篇
  1969年   6篇
  1968年   6篇
  1967年   6篇
  1966年   9篇
  1934年   5篇
  1933年   10篇
排序方式: 共有1947条查询结果,搜索用时 0 毫秒
1.
BACKGROUND: The efficacy of nasal continuous positive airway pressure (nCPAP) as a prophylactic method for preventing cardiopulmonary complications after major vascular surgery has not been investigated. PATIENTS/METHODS: In a prospective randomized trial, 204 patients undergoing elective midline laparotomy for vascular surgery were randomized to receive standard therapy ( n=105) or additional prophylactic nCPAP ( n=99) for the first postoperative night. Postoperative oxygenation, incidence of severe cardiac, and pulmonary complications, length of intensive care surveillance and length of total postoperative hospital stay (LOS) were compared. RESULTS: Prophylactic nCPAP significantly reduced the number of patients with severe oxygenation disturbances defined as paO(2) < 70 mmHg with FiO(2) > or = 0.7 (5 versus 17, P=.01). There were no differences with respect to death, cardiac and pulmonary complications, length of intensive care surveillance or LOS. CONCLUSION: Prophylactic 12 h nCPAP significantly reduces the occurrence of postoperative oxygenation disturbances but has no effect on cardiac or pulmonary complications, need for intensive care, LOS or mortality after major vascular surgery.  相似文献   
2.
Fused Thiopyrones, III: Sulfones from Methyl 4,5-Dihydro-4-oxothiopyrano[3,2-b]indole-2-carboxylate and Methyl 4,9-Dihydro-4-oxothiopyrano[2,3-b]indole-2-carboxylate On treatment with m-chloroperbenzoic acid (mCPBA) the thiopyrones 1 and 4 are oxidized to the sulfones 2 and 5 , which add ethanol to yield the thiopyranosulfones 3 and 6 as mixtures of diastereomers. In one case a 3-hydroxy compound ( 7 ) could be isolated.  相似文献   
3.
OBJECTIVE: To assess the outcome of the surgical treatment of patients who had adrenalectomy for phaeochromocytoma. DESIGN: Retrospective clinical study. SETTINGS: University hospital, Germany. SUBJECTS: 87 consecutive patients with phaeochromocytoma who were operated on. INTERVENTIONS: 29 flank and 58 transabdominal adrenalectomies between 1974 and 2000. RESULTS: The mean tumour diameter was 5 cm (range 2-13), and the mean weight 91 g (range 7-550). The postoperative hospital stay was 11 days. The flank incision entailed the shortest operating time (95 minutes). Two of the phaeochromocytomas were malignant. There were two wound infections but no deaths. With a correct selection of patients, a flank incision is safe. Endoscopic retroperitoneal adrenalectomies should be preferred.  相似文献   
4.
Twenty-four patients treated with 150 mg amitriptyline per day for an episode of major depression underwent a standardized heart rate analysis (HRA) before therapy and after 14 days. The battery of cardiovascular reflex tests included the determination of the coefficient of variation (CV) while resting and during deep respiration, a spectral analysis of heart rate, the heart rate response to standing, and the Valsalva manoeuvre. The results of the initial HRA did not differ from a group of 24 normal control subjects matched for age and sex. On day 14 of treatment the patients showed significantly reduced values of heart rate variability in all tests (P<0.0001), probably due to the anticholinergic side effects of amitriptyline. Heart rate increased form 78.1 to 93.6 bpm on average (P<0.0001). Abnormal CV at rest was registered in 96% of the patients; during deep respiration 29% showed abnormal CV results. An abnormal spectral analysis was found in 100% of the cases (low frequency peak: 42%, mid-frequency peak: 100%, high frequency peak: 79%). The heart rate response to standing was abnormal in 75% and the Valsalva test in 33% of the cases. Eighty-eight percent of the patients fulfilled the criteria of a cardiovascular autonomic neuropathy under the conditions of amitriptyline therapy. As yet, the consequences of these changes for the patients have not been sufficiently elucidated.  相似文献   
5.
3-Alkoxy-1.2.3-oxathiazolidin-4-one-2-oxides and 1-Alkoxyindolin-2-ones from N-Alkoxyglycolamides and Thionyl Chloride or 1.1′-Thionyldiimidazole The reaction of N-alkoxyglycolamides 1 with thionyl chloride or 1.1′-thionyldiimidazole is shown to produce, dependending on the substituents at C-2 in 1 , either 3-alkoxy-1.2.3-oxathiazolidin-4-one-2-oxides 4 or 1-alkoxy-3-arylindolin-2-ones 6 .  相似文献   
6.
Quantification of oxidative DNA modifications in mitochondria   总被引:2,自引:0,他引:2  
Specific repair endonucleases were used to quantify oxidativemodifications in mitochondrial DNA (mtDNA) from rat liver andfrom porcine liver and kidney by means of a relaxation assay.In rat liver mitochondria the number of modifications sensitiveto formamidopyrimidine-DNA glycosylase (FPG protein), whichinclude 8-hydroxyguanine (8-oxo-7, 8-dihydro-guanine) residues,was only 0.8±0.2 per 105 base pairs (bp). Even lowervalues were observed in porcine kidney (0.5±0.3 per 105bp) and liver (0.4±0.2 per 105 bp). The numbers of sitesof base loss (AP sites) sensitive to T4 endonuclease V and of5,6-dihydropyrimidines sensitive to endonuclease III were lessthan 0.2 per 105 bp in all cases. The data provide evidencethat the steady-state levels of oxidative mtDNA modificationsare low under physiological conditions, either because reactiveoxygen species generated in the mitochondria are instantly inactivatedor because of efficient DNA repair processes inside mitochondria.  相似文献   
7.
8.
9.
In 32 patients with acute myocardial infarction, who had undergone successful intracoronary thrombolysis, the results of regional wall motion measured from contrast cineangiograms 10 to 21 days after thrombolysis were related to the results of thallium single-photon emission computed tomography (SPECT) after intravenous dipyridamole. Wall motion was measured by means of the centerline method, and thallium defect size was estimated by comparing the patient's circumferential profile with that of 20 normals. No correlation was found between ejection fraction or regional wall motion and thallium defect size. The time from symptom onset to thrombolysis was inversely correlated with the degree of hypokinesis (r=–0.51) but not with thallium defect size. In patients treated within 3 hours, hypokinesis was significantly less than in patients treated later (–1.1±0.6 SD vs –2.2±0.8 SD, p<0.01) whereas thallium defect size was not significantly different in both groups. It is concluded that, in patients after thrombolysis, thallium defect size determined by SPECT does not reflect the degree of left ventricular dysfunction.  相似文献   
10.
BACKGROUND: The incarcerated appendix in the femoral hernia represents a rare clinical case that was first described by the Frenchman de Garengeot in 1731. Besides the open procedures, laparoscopy presented itself as a treatment option. CASE REPORT: Our case concerns a 38-year-old patient with a right femoral hernia with an inflamed incarcerated appendix. Because of the clinically inconclusive finding, we chose transperitoneal preperitoneal hernia repair (TAPP) combined with a laparoscopic appendectomy. The intra- and postoperative course was uneventful. This case shows that a laparoscopic procedure is possible even in the case of an incarceration in conjunction with an appendicitis that has not spread to the adjacent peritoneum. DISCUSSION: Compared with open interventions, the subjective social advantages (shorter hospital stay, earlier return to work, less need for pain killers, and others) of laparoscopic hernia treatment have been extensively studied. The use of both methods in the case of an incarcerated hernia is open to dispute, though various small series confirm the feasibility. CONCLUSION: Here, TAPP seems to be the more reliable method in terms of patient safety because of the simultaneous possibility of using laparoscopy.  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