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   116002篇
  免费   5921篇
  国内免费   140篇
耳鼻咽喉   1771篇
儿科学   5196篇
妇产科学   3928篇
基础医学   16067篇
口腔科学   2831篇
临床医学   8309篇
内科学   21984篇
皮肤病学   3355篇
神经病学   8977篇
特种医学   5043篇
外国民族医学   32篇
外科学   19015篇
综合类   1597篇
一般理论   29篇
预防医学   5803篇
眼科学   3390篇
药学   8042篇
中国医学   324篇
肿瘤学   6370篇
  2018年   887篇
  2017年   773篇
  2016年   1089篇
  2015年   1215篇
  2014年   1598篇
  2013年   2360篇
  2012年   3089篇
  2011年   3139篇
  2010年   1967篇
  2009年   1927篇
  2008年   3248篇
  2007年   3482篇
  2006年   3628篇
  2005年   3748篇
  2004年   3690篇
  2003年   3556篇
  2002年   3505篇
  2001年   7016篇
  2000年   6961篇
  1999年   5858篇
  1998年   1622篇
  1997年   1559篇
  1996年   1334篇
  1995年   1201篇
  1994年   1091篇
  1993年   1119篇
  1992年   3765篇
  1991年   3575篇
  1990年   3561篇
  1989年   3348篇
  1988年   2985篇
  1987年   2894篇
  1986年   2803篇
  1985年   2617篇
  1984年   1943篇
  1983年   1594篇
  1982年   927篇
  1981年   915篇
  1980年   765篇
  1979年   1822篇
  1978年   1346篇
  1977年   1111篇
  1976年   936篇
  1975年   1178篇
  1974年   1212篇
  1973年   1198篇
  1972年   1040篇
  1971年   975篇
  1970年   880篇
  1969年   787篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
92.
93.
94.
U Chikte  S Naidoo 《SADJ》2000,55(12):661-662
  相似文献   
95.
The ability of human bladder tissue extracts to cleave 14C-labelled globin in the absence and in the presence of plasminogen was assayed to quantify non-specific protease and plasminogen activator (PA) activity, respectively. In normal human bladder tissue the non-specific protease activity was approximately 2-fold higher than in tissue samples obtained from transitional cell carcinoma of the bladder (TCC). In contrast, PA activity was almost 4-fold higher in TCC than in normal transition cell epithelium. Acid-treated urine from 19 patients with TCC of the bladder exhibited significantly higher levels of plasminogen activator activity than similarly treated urine from controls. These results indicate that malignant transformation of the bladder epithelial tissue results in elevated levels of PA in the tissue and in urine. Further studies are needed to assess the potential of PA determination in the management of bladder cancer patients.  相似文献   
96.
Osteopenia of the tibia and femur caused by an external fixator in the tibia was studied in 14 rabbits. Eight rabbits were treated with a complete unilateral external fixator in one tibia, whereas the other tibia served as control. The other 6 animals had one leg operated on with inserting of all the pins but without the frame. This technique was chosen to compare osteopenia caused by stress protection and the effect of the pins. After 6 weeks, we found a 7 percent reduction in the bone mineral content in the tibial diaphyseal segment between the pins of the external fixator and no bone loss in the tibia that were operated on with only pins. In the femurs, there was a smaller decrease in the bone mineral content: respectively 3.2 percent (complete frame) and 2.9 percent (only pins). On all the operated on tibiae, there was an increase in the bone mineral content around the pins both proximally and distally.  相似文献   
97.
The pathophysiology, diagnosis, and treatment of diabetic gastroparesis are reviewed, and the mechanisms of action, pharmacokinetics, clinical efficacy, adverse effects, and dosage of metoclopramide, domperidone, and cisapride are described. Diabetic gastroparesis is a state of delayed gastric emptying that reportedly affects 20-30% of diabetic patients. Symptoms include nausea, early satiety, postprandial bloating and fullness, and vomiting. Diabetic gastroparesis has been managed most successfully with drugs that stimulate gastric emptying. Of the three agents studied--metoclopramide, domperidone, and cisapride--only metoclopramide is commercially available in the United States. The clinical efficacy of metoclopramide, domperidone, and cisapride has been well documented in several placebo-controlled trials. Metoclopramide effectively decreases mean gastric emptying time, although tolerance to this stimulation of gastric emptying may develop with long-term therapy. However, symptomatic relief persists with long-term therapy because of metoclopramide's antiemetic properties. Domperidone, which has also been shown to stimulate gastric motility and to possess antiemetic properties, improves symptoms in patients suffering from diabetic gastroparesis. Cisapride appears to have continued beneficial effects on gastric motility with long-term therapy. All three agents have favorable adverse-effect profiles. Although metoclopramide is currently the first-line agent for the management of gastroparesis, domperidone and cisapride both possess properties that may make them useful alternatives in patients who are unresponsive to or cannot tolerate metoclopramide therapy.  相似文献   
98.
99.
1. Eight conscious rabbits were repeatedly subjected to progressive reduction in central blood volume by gradually inflating a thoracic inferior vena caval-cuff so cardiac index (CI) fell at a constant 8.5% of baseline/min. 2. Caval-cuff inflations were performed after 10 min exposure to 100, 21, 12–14 and 8–10% O2, with and without the addition of 3–4% CO2, in randomized order. 3. The haemodynamic response to progressive reduction in central blood volume was biphasic. In Phase I, systemic vascular conductance index (SVCI) fell linearly, supporting mean arterial pressure (MAP). When CI had fallen to a critical level, Phase II occurred in which SVCI rose abruptly, MAP plummeted and respiratory drive progressively increased. 4. During Phase I, there were independent linear relationships between Pao2 (but not Pao2) and the rates at which SVCI and MAP changed during the progressive fall of CI. The higher the level of Pao2, the greater was the rate of fall of SVCI and the less the rate of fall of MAP. 5. There was an inverted U-shaped effect of Pao2, on the level of CI at which Phase II occurred: (a) during hyperoxia (100% O2), Phase II occurred later than during normoxia (21% O2); and (b) across the normoxic and hypoxic gas mixtures (21–8% O2, with and without added CO2), there was an independent linear relationship between Pao2 (but not Pao2 or Pao2×Pao2) and the level of CI at which Phase II occurred. That is, the lower the level of Pao2, the later was the onset of Phase II. This interaction is best explained by an increased level of central sympathetic vasoconstrictor drive during hypoxia.  相似文献   
100.
Omeprazole is a substituted benzimidazole that causes dose-dependent intracellular inhibition of gastric acid secretion in humans. This double-blind study examined the effect of omeprazole in decreasing gastric acidity and gastric residual volume in outpatient adults. Unpremedicated outpatients, ASA I-III, 18 years or older (n = 17), were randomly assigned to receive omeprazole 80 mg, or placebo by mouth the night before scheduled elective outpatient surgery. The patients were fasted for 8 h prior to surgery. After the patient was anesthetized, an orogastric tube was inserted with proper placement verified by auscultation for gastric sounds. Gastric residual contents were withdrawn into a Luken's trap, and pH was then determined and gastric volume indexed to weight (ml.kg-1). Data were analyzed by a t-test, with P less than 0.05 considered statistically significant. Patient characteristics of both groups were similar. There was a statistically significant difference between the two groups for pH (P = 0.02), but not between the two groups for gastric volume indexed to weight (P = 0.07).  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