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   612篇
  免费   135篇
  国内免费   41篇
耳鼻咽喉   14篇
儿科学   54篇
妇产科学   42篇
基础医学   85篇
口腔科学   12篇
临床医学   86篇
内科学   128篇
皮肤病学   3篇
神经病学   36篇
特种医学   82篇
外国民族医学   1篇
外科学   39篇
综合类   105篇
预防医学   26篇
眼科学   6篇
药学   29篇
中国医学   1篇
肿瘤学   39篇
  2021年   4篇
  2018年   11篇
  2017年   9篇
  2016年   12篇
  2015年   14篇
  2014年   13篇
  2013年   27篇
  2012年   14篇
  2011年   15篇
  2010年   18篇
  2009年   14篇
  2008年   16篇
  2007年   41篇
  2006年   29篇
  2005年   27篇
  2004年   19篇
  2003年   15篇
  2002年   10篇
  2001年   22篇
  2000年   16篇
  1999年   13篇
  1998年   18篇
  1997年   35篇
  1996年   27篇
  1995年   9篇
  1994年   16篇
  1993年   12篇
  1992年   11篇
  1991年   12篇
  1990年   14篇
  1989年   18篇
  1988年   22篇
  1987年   15篇
  1986年   12篇
  1985年   11篇
  1984年   9篇
  1983年   15篇
  1982年   6篇
  1981年   16篇
  1980年   16篇
  1979年   39篇
  1978年   17篇
  1977年   6篇
  1976年   12篇
  1975年   5篇
  1974年   6篇
  1973年   7篇
  1970年   5篇
  1968年   6篇
  1967年   5篇
排序方式: 共有788条查询结果,搜索用时 15 毫秒
71.
In order to investigate the metabolic effects of a constant hypertonic glucose infusion in well-oxygenated fetuses, ten experiments were carried out in nine long-term experiments in fetal lambs. It appeared that a constant hypertonic glucose infusion did not significantly affect the fetal blood gases, pH, and plasma lactate levels when fetal glucose was kept below 150 mg. per 100 ml. It was also demonstrated that glucose infusions significantly increased the fetal lactate levels and decreased the blood pH when fetal plasma glucose was over 150 mg. per 100 ml. However, there was no decrease in fetal PO2 and pco2 until fetal glucose reached values over 300 mg. per 100 ml. These studies suggest that constant hypertonic glucose infusion does not improve fetal blood gases or pH and that fetal hyperglycemia over 300 mg. per 100 ml. produces severe metabolic acidosis.  相似文献   
72.
73.
Among the various methods that can be used for the treatment of hemangiomas of the face, the use of Yttrium 90 radium needles seems to give the most satisfactory esthetic results. One application is usually sufficient to obtain disappearance of the tumor. Spontaneous regression is now a generally accepted fact, however, and the essential problem remains whether hamangiomas should be treated all when no complications are present.  相似文献   
74.
Kullmann  G; Lien  HH 《Radiology》1987,163(1):129-130
Internal bleeding in patients undergoing orchiectomy for a malignant testicular tumor can cause a dissecting hematoma in the retroperitoneum. This mass may have the clinical appearance of an iliac fossa mass and may simulate metastasis on computed tomography (CT). This condition was seen in four of 486 orchiectomy patients who underwent postoperative staging with CT. One patient is described in detail.  相似文献   
75.
In sheep fetuses 110-130 days of age acidosis (blood pH 6.95; produced by infusion with 1.1 M lactic acid) significantly lowered blood flow (ml/min/100g) to the full thickness wall of the jejunum from 135 +/- 11 to 93 +/- 14 and in the full thickness wall of the ileum from 122 +/- 13 to 95 +/- 11. The decrease was mainly due to the decline in blood flow to mucosa of the segment, where flow decreased from 182 +/- 20 to 83 +/- 14 in the jejunum and from 130 +/- 10 to 107 +/- 9 in the ileum. Fetal hypoxemia (PaO2 of 14.9 mm Hg; induced by allowing ewes to breath 11.1% O2 and 88.9% nitrogen) reduced blood flow only to the jejunal mucosa from 142 +/- 14 to 99 +/- 16. The reduction in blood flow to the full thickness wall of the jejunum and the ileum did not change significantly from the control period, when PaO2 was 25 mm Hg.  相似文献   
76.
Bisphosphonates have recently been introduced in the therapeutic armamentarium for the long-term treatment of patients with multiple myeloma (MM). These pyrophosphate analogs not only reduce the occurrence of skeletal-related events but also provide patients with a clinical benefit and improve the survival of some of them. We investigated the effects of two bisphosphonates, pamidronate and zoledronate, on both myeloma cells and bone marrow stromal cells (BMSCs). We show here that both bisphosphonates induce both myeloma cell and BMSC apoptosis. Furthermore, at lower concentrations, they induce a significant inhibition (40% and 60%, respectively) of the constitutive production of interleukin-6 (IL-6) by BMSCs. We have recently shown that BMSCs produce MMP-1, the major metalloproteinase involved in the initiation of bone resorption, production up-regulated by IL-1beta. Here, we demonstrate that zoledronate significantly inhibits MMP-1 production by BMSCs stimulated with IL-1beta more efficiently than pamidronate. However, zoledronate and to a lesser extent pamidronate are responsible for an up-regulation of MMP-2 secretion by BMSCs. MMP-2 is involved both in bone resorption and in the metastatic process. In conclusion, the apoptosis of myeloma cells and BMSCs and the inhibition of both IL-6 and MMP-1 production induced by bisphosphonates, mainly zoledronate, could have antitumoral effects in patients with MM. However, the up-regulation of MMP-2 secretion observed in vitro suggests a putative risk of tumor cell dissemination in vivo when using these new potent bisphosphonates. This potentially deleterious effect could be abolished by combining bisphosphonates with metalloproteinase inhibitors.  相似文献   
77.
We measured inulin clearance per kilogram, fractional sodium excretion per kilogram, osmolality, and urinary prostaglandin concentration in seven growth-retarded neonates and six appropriately grown neonates matched for gestational age during the first 24 hours of life to determine the effect of fetal growth retardation on renal function. There was a nonsignificant reduction in inulin clearance per kilogram in the growth-retarded neonates (p = 0.11). Inulin clearance correlated with gestational age in both groups. It was significantly correlated with birthweight in the growth-retarded group (p less than 0.05) but did not reach significance in the control group (p less than 0.06). Fractional sodium excretion was significantly higher in the growth-retarded fetuses (p less than 0.05). This increase was not explainable by differences in mean blood pressure and intravenous fluid intake, although differences in urinary prostaglandin concentrations during the study interval may be involved. In conclusion, we have demonstrated that growth retardation is associated with impaired renal maturation, which during the first 24 hours of life is manifest as decreased glomerular filtration rate and increased sodium excretion.  相似文献   
78.
79.
汉语失语症患者动词功能损伤的神经语言学分析   总被引:2,自引:0,他引:2  
目的:分析汉语失语症患者动词功能的损伤和临床病灶部位。方法:于2000-02/04在江苏省徐州市第一、二、三、四医院、解放军第九十七医院等大型医院入住的神经内科患者中选择6位典型的汉语失语症患者作为测查对象。采用北京医科大学汉语失语症成套测验检查法,同时参考波士顿诊断性失语检查法、西方失语症成套测验,并结合头颅CT的检查结果判断失语类型。根据本实验的目的,设计听觉路径和视觉路径两种测试方法。听觉路径通过语音来测试患者的动词功能知识(配价知识);视觉路径则是通过画面来测试患者的动词功能知识。最后,根据被试对测试的正确结果进行统计分析。结果:患者6例均进入结果分析。6例失语症患者的单宾语动词(二价动词)听觉路径成绩为:①字词层级,患者1的正确率为10%,患者2为55%,患者3为75%,患者4为60%,患者5为80%,患者6为35%。②语句层级,患者1的正确率为5%,患者2为40%,患者3为60%,患者4为55%,患者5为65%,患者6为30%。③篇章层级,患者1的正确率为5%,患者2为30%,患者3为50%,患者4为50%,患者5为60%,患者6为25%。6例失语症患者的二价动词视觉路径成绩为:①字词层级,患者1的正确率为15%,患者2为55%,患者3为80%,患者4为65%,患者5为85%,患者6为75%。②语句层级,患者1的正确率为10%,患者2为45%,患者3为65%,患者4为60%,患者5为75%,患者6为65%。③篇章层级,患者1的正确率为5%,患者2为35%,患者3为55%,患者4为50%,患者5为65%,患者6为60%。结论:汉语失语症患者的动词功能中受损伤程度最小的是该动词的基本价位,大脑对任何动词的各种论元结构变换都有极强的适应能力;左额下回后部对动词配价加工起主要作用,还涉及左额下回后部的周围区域和其他较远的相关区域。  相似文献   
80.
Photodynamic therapy (PDT) could be a useful adjuvant in glioblastoma treatment. The fact that epidermal growth factor (EGF) and its receptor are involved in glioblastoma growth control led us to investigate the relationships between EGF and PDT with respect to three different glioma cell lines (C6, T98 G, U87 MG) responsive to growth stimulation by EGF. Flow cytometric analysis revealed that each cell line expressed EGF receptors. PDT was then applied to the cells using haematoporphyrin derivative (HPD) as photosensitizer and argon laser irradiation. When cells were incubated for 2 h with HPD (0.1–10 μg/ml) and then laser-irradiated (λ = 514 nm; energy density 25 J/cm2), all three cell lines showed photosensitivity. The median lethal dose was respectively 3, 4.5 and 2.7 μg/ml for C6, T98 G and U87 MG. EGF (2–50 ng/ml) had no effect on HPD- and laser-induced toxicity when added to cells before PDT, whereas toxicity decreased for all three cell lines when EGF was added after PDT. HPD (1–2 μg/ml, incubation times 30–180 min) also induced an increase in EGF receptor expression for the C6 line.  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