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   216303篇
  免费   5043篇
  国内免费   564篇
耳鼻咽喉   3130篇
儿科学   7872篇
妇产科学   6342篇
基础医学   27959篇
口腔科学   7761篇
临床医学   16685篇
内科学   39701篇
皮肤病学   4957篇
神经病学   13337篇
特种医学   11042篇
外国民族医学   97篇
外科学   32153篇
综合类   1161篇
一般理论   12篇
预防医学   18308篇
眼科学   4698篇
药学   14949篇
  2篇
中国医学   316篇
肿瘤学   11428篇
  2021年   1062篇
  2019年   856篇
  2018年   4374篇
  2017年   4484篇
  2016年   3780篇
  2015年   5436篇
  2014年   5176篇
  2013年   4503篇
  2012年   11642篇
  2011年   6738篇
  2010年   3318篇
  2009年   4691篇
  2008年   3520篇
  2007年   4200篇
  2006年   4197篇
  2005年   12252篇
  2004年   13577篇
  2003年   9017篇
  2002年   4169篇
  2001年   4562篇
  2000年   1930篇
  1999年   6020篇
  1992年   6912篇
  1991年   7148篇
  1990年   7369篇
  1989年   6971篇
  1988年   6490篇
  1987年   6265篇
  1986年   5988篇
  1985年   5278篇
  1984年   3612篇
  1983年   2926篇
  1982年   1020篇
  1981年   798篇
  1980年   864篇
  1979年   3848篇
  1978年   2380篇
  1977年   1803篇
  1976年   1569篇
  1975年   2488篇
  1974年   3123篇
  1973年   2743篇
  1972年   2767篇
  1971年   2759篇
  1970年   2570篇
  1969年   2479篇
  1968年   2246篇
  1967年   2167篇
  1966年   1902篇
  1965年   1136篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
We report a case of progressive spastic paraparesis in a 45-year-old man with total portal-systemic shunting, which developed spontaneously due to congenital hepatic fibrosis. Cellular functions of the liver, except for an elevated blood ammonia level, were within normal limits, as is usual in congenital hepatic fibrosis. This case shows that spastic paraparesis following portal-systemic shunting may occur without liver failure.  相似文献   
992.
T Ebeling  P Farin  K Py?r?l? 《Atherosclerosis》1992,97(2-3):217-228
We have examined the usefulness of ultrasound (US) in the detection of Achilles tendon (AT) xanthomata in heterozygous familial hypercholesterolemia. Our study is based on 30 adult subjects with heterozygous familial hypercholesterolemia (FH) (16 men, 14 women), 27 subjects with other non-familial forms of severe hypercholesterolemia (non-FH) with serum total cholesterol levels > or = 8 mmol/l (13 men and 14 women) and 31 subjects without marked hypercholesterolemia of the same age (control group; serum total cholesterol < 8 mmol/l) (15 men, 16 women). The three groups were comparable with respect to age, sex and body mass index. In the control group the mean sagittal thickness of AT was 4.5 mm (95% CI 3.2, 5.9 mm) and the mean coronal breadth of AT 11.0 (95% CI 9.0, 13.0 mm). Mean thickness of AT was 4.9 (range 4-7) mm in the non-FH group and 11.1 (5-16) mm in the FH group. The mean breadth of AT was in these groups 12.0 (10-17) mm and 19.2 (12-27) mm, respectively. Using the upper 95% confidence interval cut-off point in the control group as a criterion for normal AT thickness and breadth, 6 (22%) of non-FH and 29 (97%) of FH patients had increased AT thickness and 5 (19%) vs. 26 (87%) patients had increased AT breadth, respectively. The sensitivity of AT thickness for identifying FH was 0.97, specificity 0.78 and positive predictive value 0.83. The sensitivity of AT breadth in identifying FH was 0.87, specificity 0.81 and positive predictive value 0.84. None of the control subjects and none of the non-FH patients showed structural abnormalities of AT in the US, whereas 89% of FH-patients showed hypoechogenicity of AT. FH-score obtained by summing up the number of abnormal US findings gave a sensitivity of 0.93, a specificity of 0.96 and a positive predictive value of 0.96 for AT US in discriminating FH from non-FH. In conclusion, US examination of AT is a useful method in the detection of AT xanthomata and thus of help in the diagnosis of heterozygous FH.  相似文献   
993.
A severe foodborne outbreak of group A streptococcal disease (T28) affected 122/169 people (72%) who attended a church party or ate leftovers from the party. The median incubation time was 42 h. Muscular pain or weakness and fatigue usually preceded pharyngeal symptoms. Complications included otitis media with perforation, peritonsillitis requiring tonsillectomy, arthritis and pericarditis. A 45-year-old man died 36 h after he developed an influenza-like illness, and at necropsy there were histological signs of early streptococcal septicaemia. The strain produced erythrogenic exotoxins B and C. Streptococci were probably transmitted by sliced eggs on sandwiches. Laboratory experiments showed that there was an increment in viable count of streptococci with 6 logs after incubation in egg yolk for 24 h at room temperature. The unusually warm climate and flaws in food handling routines contributed to this large foodborne epidemic.  相似文献   
994.
995.
996.
Mechanisms of ischemic brain damage   总被引:20,自引:0,他引:20  
This article provides a brief review of recent developments regarding the pathophysiology of ischemic brain damage, and offers hypotheses explaining the pathogenesis of selective neuronal vulnerability and of tissue infarction, respectively. It is suggested that selective neuronal vulnerability, observed after brief periods of ischemia and after hypoglycemic coma, qualifies as an excitotoxic lesion, which causes postsynaptic damage to neurons innervated by excitatory amino acids by enhancing calcium influx. However, ischemic damage often involves glial and vascular cells as well, and causes infarction. It is hypothesized that this type of brain damage is related to acidosis and that enhanced acidosis is detrimental because it accelerates delocalization of protein-bound iron, with an ensuing free-radical damage to membrane lipids and proteins.  相似文献   
997.
Bellini's duct carcinoma is a very rare tumor originating from the collecting tubules of the kidney. It should be part of differential diagnosis in cases with gross hematuria, failed diagnostic proof of a tumor within the collecting system and a centrally located hypovascular mass. Analysis of the cytoskeleton by means of cytokeratin patterns enables classification as a tumor of urothelial origin.  相似文献   
998.
999.
In the period 1970-1984 alcoholic hepatitis was diagnosed by liver biopsy in 52 females. Thirty-six patients with cirrhosis were generally in a worse clinical and biochemical state than those without cirrhosis. Biochemical tests for liver function showed significant improvement from admission to the time of liver biopsy. At follow-up liver function tests were generally better in patients who had stopped drinking alcohol compared to those who continued to do so. The 5-year survival rate was 82% for females without cirrhosis, and 45% for those with cirrhosis (p less than 0.03). Considering the sex-related differences in alcohol abuse in the general population we found no evidence of increased susceptibility to the hepatotoxic effect of alcohol in females.  相似文献   
1000.
In a prospective, double-blind, randomized multicenter trial the efficacy and safety of low molecular weight heparin and unfractionated heparin were compared for the prevention of postoperative deep vein thrombosis in patients undergoing abdominal surgery. Six hundred and seventy-three patients were randomly allocated to the two prophylaxis groups; 20 of these, however, did not undergo surgery and did not receive any prophylaxis. Of the remaining 653 patients 323 received one subcutaneous injection of 3,000 anti-Xa units of low molecular weight heparin and 330 received subcutaneously 5,000 U heparin three times a day. Treatment was initiated 2 h preoperatively and continued for 7 to 10 days. The occurrence of DVT was determined by the 125I-labelled fibrinogen uptake test and phlebography. Venous thrombosis was diagnosed in 24 of 323 patients (7.4%) treated with low molecular weight heparin and in 26 of 330 patients (7.9%) treated with low-dose heparin. DVT of proximal veins was detected in four patients of the low molecular weight heparin group and in three patients of the low-dose heparin group. During the observation period three pulmonary emboli - one fatal and two non-fatal - occurred in patients receiving prophylaxis with low-dose heparin. No pulmonary embolism was found in patients treated with low molecular weight heparin. Both prophylactic schemes were well tolerated. Intra- and postoperative blood loss, incidence of wound hematoma, frequency and volume of intra- and postoperative blood transfusion were similar in both groups with a slight advantage for the low molecular weight heparin group.(ABSTRACT TRUNCATED AT 250 WORDS)  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