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   674篇
  免费   66篇
  国内免费   25篇
耳鼻咽喉   2篇
儿科学   31篇
妇产科学   13篇
基础医学   132篇
口腔科学   7篇
临床医学   66篇
内科学   175篇
皮肤病学   6篇
神经病学   77篇
特种医学   76篇
外科学   35篇
综合类   13篇
一般理论   1篇
预防医学   55篇
眼科学   1篇
药学   35篇
肿瘤学   40篇
  2023年   3篇
  2022年   2篇
  2021年   23篇
  2020年   12篇
  2019年   12篇
  2018年   26篇
  2017年   14篇
  2016年   21篇
  2015年   15篇
  2014年   25篇
  2013年   27篇
  2012年   35篇
  2011年   55篇
  2010年   31篇
  2009年   25篇
  2008年   27篇
  2007年   49篇
  2006年   38篇
  2005年   16篇
  2004年   16篇
  2003年   22篇
  2002年   17篇
  2001年   12篇
  2000年   9篇
  1999年   15篇
  1998年   18篇
  1997年   25篇
  1996年   16篇
  1995年   18篇
  1994年   11篇
  1993年   14篇
  1992年   2篇
  1991年   6篇
  1990年   6篇
  1989年   22篇
  1988年   14篇
  1987年   8篇
  1986年   18篇
  1985年   5篇
  1984年   3篇
  1983年   4篇
  1982年   5篇
  1981年   1篇
  1980年   3篇
  1979年   2篇
  1977年   9篇
  1976年   5篇
  1975年   1篇
  1969年   1篇
  1940年   1篇
排序方式: 共有765条查询结果,搜索用时 31 毫秒
751.
Ikebuchi  K; Ihle  JN; Hirai  Y; Wong  GG; Clark  SC; Ogawa  M 《Blood》1988,72(6):2007-2014
Serial observations of blast cell colony development from spleen cells of mice treated with 5-fluorouracil (5-FU) four days earlier revealed that either form of human interleukin-1 (IL-1 alpha or IL-1 beta) hastens the emergence of interleukin-3 (IL-3)-dependent blast cell colonies. This activity was essentially indistinguishable from the effect of interleukin-6 (IL-6) or granulocyte colony-stimulating factor (G-CSF) in the same system, an effect that we have ascribed previously to a shortening of the G0 period of the dormant stem cells. We also analyzed the time courses of colony formation from cultures of day-2 post-5-FU marrow cells supported by IL-1 alpha, IL-6, or G-CSF alone or in combination with IL-3. In the presence of IL-3, G-CSF and IL-6 but not IL-1 alpha hastened the development of colonies and increased the numbers of multilineage colonies relative to cultures of IL-3 alone. This observation, together with our previous data from the human system, suggests that the synergistic effect of IL-1 is likely due to induction of secondary growth factors, including IL-6 and G-CSF, by accessory cells in culture. The effect of IL-6 on G0 was confirmed by analysis of the cycling status of progenitor cells in short-term culture. While neither IL-3 nor IL-6 alone had any effect on the cycling status, the combination of factors resulted in a rapid recruitment of quiescent cells into cell cycle (within 48 hours) as represented by a twofold increase in the numbers of multipotential progenitors and a significant increase in the sensitivity of these cells to 3H-thymidine with high specific activity. Combinational testing of all of these synergistic factors revealed that the target cell populations for the IL-1, IL-6, and G-CSF overlap considerably, suggesting that they all may act through a common mechanism. This is further supported by our finding that cells from blast cell colonies grown in the presence of a combination of any one of the synergistic factors with IL-3 replate with higher efficiency and yield more multilineage secondary colonies than those from colonies grown in IL-3 alone. These findings provide further evidence that IL-1, IL-6, and G- CSF serve to integrate the immediate host responses to infection through augmentation of effector cells and antibody production as well as the longer term host responses by recruitment of dormant hemopoietic stem cells into active cell cycling.  相似文献   
752.
A low plasma 25-OH vitamin D3 level is a universal risk factor for a wide range of diseases and has also been implicated in late-life depression. It is currently unknown whether the biologically active form of vitamin D, that is, 1,25-(OH)2 vitamin D3, is also decreased in late-life depression, or whether vitamin D levels correlate with specific depression characteristics. We determined plasma 25-OH vitamin D3, 1,25-(OH)2 vitamin D3 and parathormone levels in 355 depressed older persons and 124 non-depressed comparison subjects (age⩾60 years). Psychopathology was established with the Composite International Diagnostic Interview 2.1, together with potential confounders and depression characteristics (severity, symptom profile, age of onset, recurrence, chronicity and antidepressant drug use). Adjusted for confounders, depressed patients had significantly lower levels of 25-OH vitamin D33 (Cohen''s d =0.28 (95% confidence interval: 0.07–0.49), P=0.033) as well as 1,25-(OH)2 vitamin D3 (Cohen''s d =0.48 (95% confidence interval: 0.27–0.70), P<0.001) than comparison subjects. Of all depression characteristics tested, only the use of tricyclic antidepressants (TCAs) was significantly correlated with lower 1,25-(OH)2 vitamin D3 levels (Cohen''s d =0.86 (95% confidence interval: 0.53–1.19), P<0.001), but not its often measured precursor 25-OH vitamin D3. As vitamin D levels were significantly lower after adjustment for confounders, vitamin D might have an aetiological role in late-life depression. Differences between depressed and non-depressed subjects were largest for the biologically active form of vitamin D. The differential impact of TCAs on 25-OH vitamin D3 and 1,25-(OH)2 vitamin D3 levels suggests modulation of 1-α-hydroxylase and/or 24-hydroxylase, which may in turn have clinical implications for biological ageing mechanisms in late-life depression.  相似文献   
753.
Mastocytosis is an emerging differential diagnosis in patients with more or less specific mediator‐related symptoms. In some of these patients, typical skin lesions are found and the diagnosis of mastocytosis can be established. In other cases, however, skin lesions are absent, which represents a diagnostic challenge. In the light of this unmet need, we developed a diagnostic algorithm for patients with suspected mastocytosis. In adult patients with typical lesions of mastocytosis in the skin, a bone marrow (BM) biopsy should be considered, regardless of the basal serum tryptase concentration. In adults without skin lesions who suffer from mediator‐related or other typical symptoms, the basal tryptase level is an important parameter. In those with a slightly increased tryptase level, additional investigations, including a sensitive KIT mutation analysis of blood leucocytes or measurement of urinary histamine metabolites, may be helpful. In adult patients in whom (i) KIT D816V is detected and/or (ii) the basal serum tryptase level is clearly increased (>25–30 ng/ml) and/or (iii) other clinical or laboratory features suggest the presence of ‘occult’ mastocytosis or another haematologic neoplasm, a BM investigation is recommended. In the absence of KIT D816V and other signs or symptoms of mastocytosis or another haematopoietic disease, no BM investigation is required, but the clinical course and tryptase levels are monitored in the follow‐up. In paediatric patients, a BM investigation is usually not required, even if the tryptase level is increased. Although validation is required, it can be expected that the algorithm proposed herein will facilitate the management of patients with suspected mastocytosis and help avoid unnecessary referrals and investigations.  相似文献   
754.
Melatonin improves survival and functional impairment including hemolysis, thrombocytopenia, and hypotension when administered in a prophylactic manner or early after initiation of sepsis or endotoxemia. In the present study, melatonin was given not before first symptoms of systemic inflammation became manifest. Lipopolysaccharide was infused at a rate of 0.5 mg/kg × h to induce systemic inflammation in male Wistar rats. Melatonin (single dose 3 mg/kg × 15 min) was intravenously administered 180 and 270 min after starting of the lipopolysaccharide infusion. Systemic and vital parameters (e.g., systemic blood pressure and breathing rate) as well as blood and plasma parameters (acid-base parameters; electrolytes; parameters of tissue injury such as glucose concentration, lactate concentration, hemolysis, and aminotransferase activities; parameters of thromboelastometry; and platelet count) were determined in regular intervals. Infusion of lipopolysaccharide led to characteristic symptoms of severe systemic inflammation including hypotension, metabolic acidosis and hypoglycemia, electrolyte and hemostatic disturbances, thrombocytopenia, and hemolysis. Melatonin neither decreased mortality nor reduced lipopolysaccharide-dependent changes to vital, blood, and plasma parameters. Even though melatonin may have a beneficial effect in early stages of systemic inflammation, it can hardly be an option in therapy of manifest sepsis or endotoxemia in an intensive care unit.  相似文献   
755.
756.
目的:描述安徽省青少年的留守状况,探索不同类型青少年留守率的差异.方法:采用分层整群抽样的方法抽取皖南、皖北城乡普通中学7所,获得样本3 421人,其中留守青少年682人.自行设计流行病学凋查表对研究对象的一般人口学特征和留守状况进行问卷调查.结果:安徽省10 ~ 18岁青少年的留守率为19.94%.不同类型青少年留守...  相似文献   
757.
Background / PurposeSacrococcygeal pilonidal sinus disease (PSD) has an incidence of 1.2–2.5/1000 in children. Onset is around puberty. Symptoms of recurrent abscess and chronic suppuration may interfere with education and social integration. Treatments should cause minimal disruption while having good cure and recurrence rates. Curettage and Fibrin glue obliteration (FGO) show promising results in adults. We present our experience of its use in children.MethodsReview of all pediatric patients receiving FGO of pilonidal sinus performed by a single surgeon from September 2014 to February 2018.ResultsEighteen patients were identified. Median age was 16 (range 15–17), 55.6% were male. All procedures were completed as day cases. Median operative duration was 14 .1 (6–29) min. Twelve patients required only 1 procedure, 4 required 2 procedures, 1 required 5 procedures and 1 elected for formal excision after 2 FGO treatments. Median return to normal activities was 3 days, with 1 day school absence. Two patients developed minor surgical site infections. Median follow-up was 52 weeks (17–102), during which time there was 1 recurrence (5.6%).ConclusionThis study demonstrates FGO is a safe, effective procedure for pediatric PNS, with results comparable to off-midline flap techniques and without the need for extensive tissue excision and the associated morbidity.Level of evidenceIV  相似文献   
758.
759.
760.

Objective

To determine the prevalence of persisting endoanal ultrasonographic defects among women with obstetric anal sphincter injuries (OASIS), and the incidence of defecatory symptoms.

Methods

In a prospective study in Enschede, Netherlands, women with OASIS were enrolled between 2007 and 2012. Three months after surgical repair, all women had an endoanal ultrasound, and data were collected on gas and fecal incontinence, soiling, and fecal urgency.

Results

Overall, 99 women were included. At follow-up, 35 (35.4%) women had a persisting defect of the external anal sphincter on ultrasound, and 5 women (5.1%) also had a persisting defect of the internal anal sphincter. Overall, 35 (35.4%) women had one or more defecatory complaints—predominantly involuntary loss of gas and fecal urgency. Overall, 22 of 35 (63.0%) women with and 13 of 64 (20.3%) women without a persisting defect on ultrasound had defecatory complaints. The number of defecatory symptoms showed a positive correlation with severity of injury. Women with a persisting defect had a threefold higher risk of defecatory complaints as compared with women who had a successful repair (odds ratio, 6.6; 95% confidence interval, 2.6–16.6).

Conclusion

The results emphasize the importance of adequate repair of OASIS and demonstrate that repair can be difficult or underestimated.  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