首页 | 官方网站   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   35688篇
  免费   1792篇
  国内免费   225篇
医药卫生   37705篇
  2024年   26篇
  2023年   281篇
  2022年   636篇
  2021年   1379篇
  2020年   714篇
  2019年   1207篇
  2018年   1416篇
  2017年   842篇
  2016年   824篇
  2015年   1042篇
  2014年   1551篇
  2013年   1797篇
  2012年   3012篇
  2011年   3165篇
  2010年   1653篇
  2009年   1529篇
  2008年   2364篇
  2007年   2447篇
  2006年   2245篇
  2005年   2090篇
  2004年   1870篇
  2003年   1588篇
  2002年   1552篇
  2001年   191篇
  2000年   178篇
  1999年   202篇
  1998年   252篇
  1997年   239篇
  1996年   171篇
  1995年   124篇
  1994年   112篇
  1993年   117篇
  1992年   89篇
  1991年   78篇
  1990年   74篇
  1989年   41篇
  1988年   35篇
  1987年   30篇
  1986年   41篇
  1985年   39篇
  1984年   48篇
  1983年   35篇
  1982年   45篇
  1981年   52篇
  1980年   29篇
  1979年   30篇
  1976年   17篇
  1975年   21篇
  1974年   20篇
  1971年   20篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
22.
23.
Five patients with idiopathic transient osteoporosis were examined. Bone scanning and MRI was helpful in the diagnosis to differentiate of necrosis and all patients recovered completely with conservative and symptomatic treatment. There was no history of trauma in all patients. MRI was realized previously in all cases to confirm the diagnosis and after the resolution of symptomathology.  相似文献   
24.
Members of the R7 subfamily of regulators of G-protein signaling (RGS) proteins (RGS6, RGS7, RGS9-2, and RGS11) are found in the mouse CNS. The expression of these proteins was effectively reduced in different neural structures by blocking their mRNA with antisense oligodeoxynucleotides (ODNs). This was achieved without noticeable changes in the binding characteristics of labeled beta-endorphin to opioid receptors. Knockdown of R7 proteins enhanced the potency of antinociception promoted by morphine and [D-Ala(2), N-MePhe(4), Gly-ol(5)]-enkephalin (DAMGO)-both agonists at mu-opioid receptors. The duration of morphine analgesia was greatly increased in RGS9-2 and in RGS11 knockdown mice. The impairment of R7 proteins brought about different changes in the analgesic activity of selective delta agonists. Knockdown of RGS11 reduced [D-Ala(2)]deltorphin II analgesic effects. Those of RGS6 and RGS9-2 proteins caused [D-Ala(2)]deltorphin II to produce a smoothened time-course curve-the peak effect blunted and analgesia extended during the declining phase. RGS9-2 impairment also promoted a similar pattern of change for [D-Pen(2,5)]-enkephalin (DPDPE). RGS7-deficient mice showed an increased response to both [D-Ala(2)]deltorphin II and DPDPE analgesic effects. A single intracerebroventricular (i.c.v.) ED(80) analgesic dose of morphine gave rise to acute tolerance in control mice, but did not promote tolerance in RGS6, RGS7, RGS9-2, or RGS11 knockdown animals. Thus, R7 proteins play a critical role in agonist tachyphylaxis and acute tolerance at mu-opioid receptors, and show differences in their modulation of delta-opioid receptors.  相似文献   
25.
The study objectives were to analyze the changes in exhaled carbon monoxide (COex) induced by histamine provocation challenge in asthmatic patients and to evaluate the relationship between COex and airway sensitivity and reactivity. Levels of COex were measured in 105 nonsmoking mildly asthmatic subjects before and after histamine provocation challenge. Dose-response curves were characterized by their sensitivity (PD20) and reactivity. Dose-response slope (DRS), continuous index of responsiveness (CIR), and bronchial reactivity index (BRI) were determined as reactivity indices. Bronchial challenge was positive for 47 subjects and negative for 58. The COex levels rose significantly after bronchial challenge in the positive response group (4.49 ± 0.4 vs. 5.74 ± 0.57 ppm, p = 0.025) and in the negative response group (2.84 ± 0.25 vs 4.00 ± 0.41 ppm, p = 0.000). An inverse relation between basal COex and PD20 was found (r = - 0.318, p = 0.030). In all subjects, a proportional direct relationship between COex and DRS (r = 0.214, p = 0.015), CIR (r = 0.401, p = 0.000), and BRI (r = 0.208, p = 0.012) was observed. On stepwise multiple linear regression analysis, COex only significantly correlated with CIR (multiple r2 = 0.174, p = 0.000). In conclusion, exhaled CO determination is a noninvasive inflammatory marker of the respiratory tract, which shows an acceptable association with airway hyperresponsiveness.  相似文献   
26.
27.
This study aimed to determine whether a weight-adjusted dose of subcutaneous enoxaparin is as effective and safe as oral acenocoumarol for the secondary prophylaxis of pulmonary embolism. Three hundred and eighty consecutive noncancer outpatients hospitalized with an episode of symptomatic pulmonary embolism selected treatment with acenocoumarol or enoxaparin at a dose of 1 mg/kg once daily after being informed of the type of administration and expected frequency of laboratory monitoring for both medicinal products. Endpoints were symptomatic recurrent thromboembolic events evaluated by standard objective testing, and a composite endpoint of recurrent venous thromboembolism, major bleeding, and death from any cause. One hundred and ninety-nine patients (52%) chose acenocoumarol therapy and 181 chose enoxaparin monotherapy. Four patients in the enoxaparin group (2.2%) and six patients in the acenocoumarol group (3%) had an objective thromboembolic recurrence (hazard ratio, 1.35; 95% confidence interval, 0.38-4.79; P = 0.64). Nine patients in the enoxaparin group (5.0%) had a hemorrhagic complication compared with 11 in the acenocoumarol group (5.5%) (P = 0.81). The hospital length of stay was shorter with enoxaparin compared with acenocoumarol (11 versus 16 days, P = 0.0001). Enoxaparin is as effective and safe as acenocoumarol in the secondary prevention of recurrent thromboembolic disease and is associated with shorter hospitalization.  相似文献   
28.
29.
30.
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-23

京公网安备 11010802026262号