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   6829篇
  免费   720篇
  国内免费   30篇
耳鼻咽喉   65篇
儿科学   332篇
妇产科学   83篇
基础医学   806篇
口腔科学   164篇
临床医学   681篇
内科学   1306篇
皮肤病学   368篇
神经病学   457篇
特种医学   470篇
外科学   990篇
综合类   178篇
一般理论   8篇
预防医学   516篇
眼科学   44篇
药学   451篇
中国医学   3篇
肿瘤学   657篇
  2021年   72篇
  2019年   78篇
  2018年   94篇
  2017年   62篇
  2016年   78篇
  2015年   84篇
  2014年   106篇
  2013年   144篇
  2012年   197篇
  2011年   201篇
  2010年   163篇
  2009年   142篇
  2008年   228篇
  2007年   253篇
  2006年   262篇
  2005年   245篇
  2004年   227篇
  2003年   243篇
  2002年   192篇
  2001年   207篇
  2000年   226篇
  1999年   213篇
  1998年   128篇
  1997年   141篇
  1996年   155篇
  1995年   123篇
  1994年   93篇
  1993年   92篇
  1992年   161篇
  1991年   192篇
  1990年   181篇
  1989年   174篇
  1988年   212篇
  1987年   186篇
  1986年   159篇
  1985年   199篇
  1984年   114篇
  1983年   123篇
  1982年   74篇
  1981年   71篇
  1980年   62篇
  1979年   109篇
  1978年   101篇
  1977年   82篇
  1976年   79篇
  1975年   72篇
  1974年   93篇
  1973年   100篇
  1972年   72篇
  1971年   72篇
排序方式: 共有7579条查询结果,搜索用时 15 毫秒
951.
952.
953.
We report two cases in which combined surgical clipping and endovascular coils have been used to treat intracranial aneurysms. In one case, a 59-year-old woman with multiple episodes of subarachnoid hemorrhage had an anterior communicating artery aneurysm, which was initially treated with coils and then clipped to occlude the aneurysm securely. In the second case, a broad-based cavernous aneurysm could not be completely surgically occluded, but surgical clipping did decrease the aneurysm neck size, allowing it to be successfully treated with coils.  相似文献   
954.
PURPOSETo compare the detectability of vertebral metastatic disease on T1-weighted, short-inversion-time inversion recovery (STIR), fast spin-echo (FSE), fat-saturated FSE, and inversion recovery FSE (IRFSE) MR sequences using percent contrast and contrast-to-noise ratios.METHODSPatients with proved metastatic disease underwent imaging on a 1.5-T MR system with sagittal T1-weighted (800/20/2 [repetition time/echo time/excitations]) (91 patients), STIR (1400/43/2; inversion time, 140) (91 patients), FSE (4000/180/2) (46 patients), fat-saturated FSE (4000/180/2) (16 patients), and IRFSE (29 patients) sequences. Percent contrast and contrast-to-noise ratio were calculated for the lesions. The number of metastatic lesions detected with each of the pulse sequences was also calculated.RESULTSMean percent contrast was, for T1-weighted sequence, -42.2 +/- 1%; STIR, 262 +/- 34%; FSE, 121 +/- 21%; fat-saturated FSE, 182 +/- 6%; and IRFSE, 272 +/- 47%. The mean contrast-to-noise ratio for T1-weighted was -4.63 +/- 1.7; STIR, 10.8 +/- .98; FSE, 4.16 +/- .76; fat-saturated FSE, 4.87 +/- .19; and IRFSE, 5.2 +/- .87. STIR and IRFSE showed the highest number of lesions, followed by T1-weighted, fat-saturated FSE, and FSE sequences. T1-weighted sequences showed 94%, FSE 55%, and fat-saturated FSE 78% of the lesions detected. Epidural metastatic lesions were better depicted on T1-weighted, FSE, and fat-saturated FSE sequences.CONCLUSIONSTIR was superior to both T1-weighted and FSE (with and without fat saturation) for detection of metastatic lesions, in terms of both percent contrast and contrast-to-noise ratio and visibility. IRFSE was equal to STIR for the detection of metastasis by both subjective and objective criteria. T1-weighted, FSE, and fat-saturated FSE sequences were superior to STIR and IRFSE in the detection of epidural metastatic disease. IRFSE provided faster scanning time, which could be translated into greater resolution.  相似文献   
955.
OBJECTIVE Vitamin D intoxication is a relatively rare but treatable cause of hypercalcaemia. In the past this has been undertaken using corticosteroids. Previous observations have suggested that there is increased bone resorption in hypervitaminosis D. If this were to be the case, specific inhibitors of bone resorption might provide more effective treatment. We have therefore studied the mechanisms of hypercalcaemia and response to therapy in a group of patients with vitamin D intoxication. DESIGN Vitamin D metabolites were measured in six patients with vitamin D intoxication; in five of these the components of hypercalcaemia were calculated. These measurements were repeated following treatment with corticosteroids (two patients) or the bisphosphonate, pamidronate (three patients). RESULTS In each case the serum 25-hydroxyvitamin D was grossly elevated and there was a more modest elevation in serum 1,25-dihydroxyvitamin D. The components of hypercalcaemia suggest that there was a significant degree of bone resorption in all six patients and that this Is the major determinant of hypercaicaemia. Pamidronate treatment resulted in a brisk reduction in plasma calcium concentration. Following corticosteroids the return of calcium to normal was more delayed. CONCLUSION The hypercalcaemia of vitamin D intoxication is mediated by Increased bone resorption and bisphosphonates have a role in its management.  相似文献   
956.
957.
958.
BACKGROUND: Pantoprazole is a substituted benzimidazole which is a potent inhibitor of gastric acid secretion by its action upon H+, K+- ATPase. METHODS: Pantoprazole 40 mg and 80 mg were compared in a randomized double-blind study in 192 out-patients with stage II or III (Savary-Miller classification) reflux oesophagitis. Patients received either pantoprazole 40 mg (n = 97) or pantoprazole 80 mg (n = 95), once daily before breakfast for 4 weeks. Treatment was extended for a further 4 weeks if the oesophagitis had not healed. RESULTS: After 4 weeks complete healing of the reflux oesophagitis was seen in 78% of protocol-correct patients given pantoprazole 40 mg daily (n = 86), and in 72% in the 80 mg (n = 87) group. The cumulative healing rates after 8 weeks were 95 and 94%, respectively (P > 0.05, Cochran-Mantel- Haenszel), and time until healing of oesophagitis comparable in both groups. Differences between doses were also not significant in an intention-to-treat analysis. Both dosing schedules were well tolerated and the patients experienced remarkable symptom relief. No adverse event or changes in laboratory values of clinical significance could definitely be ascribed to the trial medication. CONCLUSION: The 40 mg pantoprazole dosage is comparable to 80 mg in reflux oesophagitis, both in efficacy and tolerability.  相似文献   
959.
Renal vein renin determinations, in contrast to isolated peripheral venous renin determinations, provide great help in the selection of patients who can benefit from an operation for renal hypertension. Patients with essential hypertension usually have renal vein renin ratios, larger/smaller, close to unity, but the available cumulative data show that, statistically, ratios as large as 2.0 may occur in this group (95 per cent confidence limits). In patients with unilateral stenosis of a main renal artery, large renal vein renin ratios (stenotic/normal) have been followed by operative success in more than 90 per cent of patients. However, many operative successes have also been achieved in patients without a large renal vein renin ratio. This may be explained by inaccurate renal vein catheterization, inactive renin secretion, nonsimultaneous sampling, assay variability, and problems related to bilateral or segmental lesions. Recent refinements in the interpretation of renal vein renin data (contralateral suppression, ipsilateral hypersecretion in absolute terms, and a combination analysis scoring system) appear to increase the accuracy of the test. Detailed anatomic information, provided by arteriography, is essential for proper interpretation of renal vein renin data.  相似文献   
960.
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