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   1126篇
  免费   96篇
  国内免费   6篇
耳鼻咽喉   5篇
儿科学   48篇
妇产科学   12篇
基础医学   120篇
口腔科学   53篇
临床医学   143篇
内科学   216篇
皮肤病学   26篇
神经病学   63篇
特种医学   226篇
外科学   76篇
综合类   24篇
一般理论   1篇
预防医学   75篇
眼科学   17篇
药学   70篇
肿瘤学   53篇
  2021年   9篇
  2020年   8篇
  2019年   7篇
  2018年   17篇
  2017年   12篇
  2016年   12篇
  2015年   17篇
  2014年   25篇
  2013年   28篇
  2012年   36篇
  2011年   31篇
  2010年   41篇
  2009年   38篇
  2008年   34篇
  2007年   41篇
  2006年   24篇
  2005年   25篇
  2004年   21篇
  2003年   8篇
  2002年   18篇
  2001年   11篇
  2000年   12篇
  1999年   13篇
  1998年   50篇
  1997年   63篇
  1996年   58篇
  1995年   52篇
  1994年   50篇
  1993年   33篇
  1992年   16篇
  1991年   15篇
  1990年   19篇
  1989年   32篇
  1988年   36篇
  1987年   24篇
  1986年   37篇
  1985年   33篇
  1984年   18篇
  1983年   29篇
  1982年   24篇
  1981年   20篇
  1980年   22篇
  1979年   14篇
  1978年   10篇
  1977年   12篇
  1976年   20篇
  1975年   10篇
  1973年   6篇
  1972年   8篇
  1971年   5篇
排序方式: 共有1228条查询结果,搜索用时 15 毫秒
71.
Ten haemophilia centres in northern Europe have pooled data on 202 haemophilic children who were infected with HIV between 1979 and 1986. All cases were under 16 years of age on 1 July 1985. The age at infection ranged from 1-15 years. Thirty seven cases (18%) had progressed to AIDS by 1 July 1991 and 15 of these have died. Persistent generalised lymphadenopathy has been noted in 102 patients of whom 18 (17%) have developed AIDS. Twenty three of the remaining patients (23%) have not. CD4+ T cell counts have fallen steadily. Of 36 patients who have had shingles since seroconversion, 19 (53%) had counts below 0.2 x 10(9)/l. Thirty five out of 145 patients without shingles (24%) had similar values. The mean IgA concentration in patients with CD4+ T cell counts above 0.5 x 10(9)/l was 2.38 g/l, between 0.2 and 0.5 was 3.07 g/l, and in those with CD4+ T cell counts below 0.2 x 10(9)/l the mean IgA concentration was 4.58 g/l. Treatment patterns have altered between 1989 and 1991, with increased use of zidovudine in patients without AIDS and a marked increase in primary prophylaxis against pneumocystis pneumonia. This has been associated with a decline in the incidence of pneumocystis as an indicator disease in new AIDS cases from 56% in 1989 to 20% in 1991. These observations indicate that persistent generalised lymphadenopathy does not worsen the outlook, but shingles does. Rising IgA concentrations are markers for disease progression. Modern prophylactic regimens are delaying the onset of indicator disease, but CD4 values continue to fall steadily.  相似文献   
72.
Fat and mineral metabolic balance studies were performed in 25 normal very low-birth-weight infants ( 1500 g at birth) fed either pooled pasteurized human milk supplemented with calcium, phosphorus and magnesium, or a preterm formula. Calcium, phosphorus and magnesium intake were similar in both groups and averaged 100mg/kg/day, 72 mg/kg/day and 8 mg/kg/day, respectively. Calcium and phosphorus retention was higher in the subjects fed fortified human milk than in those receiving a preterm formula (65±14 and 62±9mg/kg/day versus 55±12 and 47±7mg/kg/day respectively). The difference was only significant for phosphorus. Magnesium retention was similar in the two groups and averaged 3 mg/kg/day. Fat intake and absorption was significantly higher in the preterm formula fed group than in the one fed fortified human milk (5.5±0.4 g/kg/day and 88±4% versus 4.2±1 g/kg/day, 79±6% respectively). Assessment of the whole body bone mineral content by dual energy X-ray absorptiometry was performed at 3 and 6 months of age in another group of 25 low-birth-weight infants fed either fortified human milk or a preterm formula. Whole body bone mineral content (BMCt) was low (43.3±30.8 g of hydroxyapatite) at 3 months of age (theoretical term) compared to normal full-term newborns at birth. There was no significant influence of the diet. At 6 months of age, BMCt reached 168.6±36.6g, a value similar to that of full-term newborns, with no significant difference between the two regimen groups. The deficit in the 12 subjects who had a BMCt under 30 g at 3 months of age had been corrected at age 6 months. Premature babies fed a pooled pasteurized human milk enriched with calcium, phosphorus and magnesium favored a better retention of calcium and phosphorus. However, no significant influence of the two diets studied was observed on the gain in BMCt over the first 6 months of life.  相似文献   
73.
74.
75.
The effect of rat atrial natriuretic peptide (ANP) on basal hemodynamic and hormonal function and on the response to acute hemorrhage was studied in eight conscious sheep. ANP infusions (3 micrograms/kg BW bolus, followed by 50 ng/kg.min for 70 min) increased plasma immunoreactive ANP levels from less than 12 pmol/liter to steady state levels of 523 +/- 20 pmol/liter, reduced arterial pressure by 14% (P less than 0.002), increased heart rate by 26% (P less than 0.06), and increased plasma norepinephrine levels (P less than 0.015) compared to control values. These changes were associated with a significant increase in plasma cortisol (P less than 0.05) and smaller increases in plasma ACTH and arginine vasopressin (AVP), but plasma angiotensin II (AII) and aldosterone were unaffected. When hemorrhage (15 ml/kg BW over 10 min) was performed during ANP or control infusions, hypotension was greater (P less than 0.0004) during ANP treatment and the responses of plasma ACTH, AVP, catecholamines, and AII were enhanced compared with those to control hemorrhage. Plasma immunoreactive ANP during ANP infusions was significantly higher after hemorrhage (mean, 833 +/- 46; P less than 0.003), but the disappearance rate after the termination of ANP infusion was the same (3.1 min) with or without hemorrhage. These studies show that ANP infusions, achieving plasma levels observed in pathological states such as congestive heart failure, inhibit the expected responses of plasma AII and aldosterone to mild acute hypotension, but do not inhibit the responses of plasma AVP, ACTH, AII, and aldosterone associated with acute moderate hemorrhage in conscious sheep.  相似文献   
76.
77.
Pulsed Doppler angiography in lower limb arterial ischemia.   总被引:1,自引:0,他引:1  
A 30-channel pulsed Doppler vessel imaging system (MAVIS, GEC Medical, Middlesex, England), was used to obtain images and maximal Doppler velocity time waveforms in the diagnosis of stenosis of the origin of the profunda femoris artery (PFA) and in the detection of structural changes within Dacron arterial grafts. In PFA scans of 33 limbs in 22 patients (mean age, 52 years), PFA stenosis of more than 50% at operation was invariably associated with a damping factor of the maximal Doppler velocity-time waveform of greater than 1.5 (eight limbs). In 12 limbs with a normal PFA at operation, the damping factor was always less than 1.4, and in 13 limbs of normal patients without arterial disease, the damping factor was always less than 1.34. In studies of 10 mm arterial grafts, the internal diameter of 14 iliopopliteal grafts scanned just above the popliteal anastomosis was strikingly reduced as compared with the femoral anastomosis of 14 aortoiliofemoral grafts and seven axillobifemoral grafts. These preliminary results suggest that MAVIS studies can be used noninvasively to detect PFA stenosis and to identify luminal narrowing of iliopopliteal grafts.  相似文献   
78.
79.
1 Salbutamol and disodium cromoglycate were compared for anti-anaphylactic activity against passive anaphylaxis in rat skin and peritoneum in vivo and in rat mast cells and human lung fragments in vitro.

2 Salbutamol administered intravenously to rats inhibited cutaneous anaphylaxis, but also inhibited cutaneous responses to histamine and 5-hydroxytryptamine. Salbutamol administered intraperitoneally inhibited the release of slow reacting substance of anaphylaxis (SRS-A) but not the release of histamine in the peritoneum. It was a very weak inhibitor of histamine release from rat mast cells in vitro.

3 Disodium cromoglycate administered intravenously to rats inhibited cutaneous anaphylaxis. Disodium cromoglycate administered intraperitoneally to rats inhibited the release of histamine and, to a lesser extent, SRS-A in the peritoneum. It was an effective but short-acting inhibitor of histamine release from rat mast cells in vitro.

4 Salbutamol was a potent inhibitor of the anaphylactic release of histamine and SRS-A from fragments of human lung.

5 Disodium cromoglycate was a weak inhibitor of the anaphylactic release of histamine and SRS-A from fragments of human lung. The inhibition was variable and not dose-related.

6 The concentration of salbutamol required to inhibit anaphylaxis in human lung is of the same order as that required to relax human bronchial muscle. It is suggested that salbutamol may be more effective in allergic asthma if given in a prophylactic regimen.

  相似文献   
80.
Som  PM; Krespi  YP 《Radiology》1979,133(2):341
  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