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   5120篇
  免费   213篇
  国内免费   20篇
耳鼻咽喉   207篇
儿科学   226篇
妇产科学   226篇
基础医学   707篇
口腔科学   48篇
临床医学   325篇
内科学   1155篇
皮肤病学   67篇
神经病学   471篇
特种医学   108篇
外科学   320篇
综合类   38篇
一般理论   1篇
预防医学   400篇
眼科学   100篇
药学   688篇
中国医学   12篇
肿瘤学   254篇
  2024年   4篇
  2023年   31篇
  2022年   177篇
  2021年   368篇
  2020年   134篇
  2019年   157篇
  2018年   187篇
  2017年   143篇
  2016年   154篇
  2015年   190篇
  2014年   218篇
  2013年   275篇
  2012年   432篇
  2011年   484篇
  2010年   225篇
  2009年   142篇
  2008年   277篇
  2007年   330篇
  2006年   316篇
  2005年   307篇
  2004年   300篇
  2003年   236篇
  2002年   169篇
  2001年   8篇
  2000年   6篇
  1999年   8篇
  1998年   7篇
  1997年   8篇
  1996年   8篇
  1995年   8篇
  1994年   4篇
  1993年   1篇
  1992年   1篇
  1991年   4篇
  1990年   2篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1985年   2篇
  1984年   4篇
  1982年   1篇
  1981年   4篇
  1980年   2篇
  1979年   2篇
  1978年   6篇
  1976年   1篇
  1975年   4篇
  1966年   1篇
  1908年   1篇
排序方式: 共有5353条查询结果,搜索用时 140 毫秒
111.
112.
113.
Administration of streptozotocin (STZ) and nicotinamide (NA) to adult rats allows for the induction of mild diabetes. However, this experimental model has not been fully characterized. This study was undertaken to determine the metabolic and secretory activity of adipose tissue in rats with STZ‐NA‐induced diabetes. Experiments were performed using epididymal adipocytes isolated from control and mildly diabetic rats. Lipogenesis, glucose transport as well as glucose and alanine oxidation, lipolysis, anti‐lipolysis, cAMP levels and adipokine secretion were compared in cells isolated from the control and diabetic rats. Lipogenesis, glucose transport and oxidation were diminished in the adipocytes of diabetic rats compared with the fat cells of control animals. However, alanine oxidation appeared to be similar in the cells of non‐diabetic and diabetic animals. Lipolytic response to low epinephrine concentrations was slightly increased in the adipocytes of diabetic rats; however, at higher concentrations of the hormone, lipolysis was similar in both groups of cells. The epinephrine‐induced rise in cAMP levels was higher in the adipocytes of STZ‐NA‐induced diabetic rats, even in the presence of insulin. Lipolysis stimulated by dibutyryl‐cAMP did not significantly differ, whereas anti‐lipolytic effects of insulin were mildly decreased in the cells of diabetic rats. Secretion of adiponectin and leptin was substantially diminished in the adipocytes of diabetic rats compared with the cells of control animals. Our studies demonstrated that the balance between lipogenesis and lipolysis in the adipose tissue of rats with mild diabetes induced by STZ and NA is slightly shifted towards reduced lipid accumulation. Simultaneously, adiponectin and leptin secretion is significantly impaired.  相似文献   
114.
Serum complement cascade, a part of innate immunity required for host protection against invading pathogens, is also a mediator of various forms of disease and injury. It is activated by classical, lectin, and alternative pathways that lead to activation of C3 component by C3 convertases, release of C3b opsonin, C5 conversion and eventually membrane attack complex formation. The tightly regulated activation process yields also C3a and C5a anaphylatoxins, which target a broad spectrum of immune and non-immune cells. The review discusses the involvement of the complement cascade in kidney disease pathogenesis and injury. The role of the complement pathways in autoantibody-mediated forms of glomerulonephritis (lupus nephritis, anti-glomerular basement membrane disease, anti-neutrophil cytoplasmic autoantibody-induced or membranoproliferative glomerulonephritis, membranous nephropathy), C3 glomerulopathy, atypical forms of hemolytic uremic syndrome, ischemic-reperfusion injury of transplanted kidney, and antibody-mediated renal allograft rejection are discussed. The disturbances in complement activation and regulation with underlying genetics are presented and related to observed pathology. Also promising strategies targeting the complement system in complement-related disorders are mentioned.  相似文献   
115.
116.
AIM: To determine the prevalence and characteristics of additional primary malignancies in gastric cancer (GC) patients.METHODS: GC patients (862 total; 570 men, 292 women; mean age 59.8 ± 12.8 years) diagnosed at the Department of Gastroenterology at Pomeranian Medical University over a period of 23 years were included in this retrospective analysis of a prospectively maintained database. Mean follow-up time was 31.3 ± 38.6 mo (range 1-241 mo). The following clinicopathological features of patients with synchronous tumors were compared to those with metachronous tumors: age, sex, symptom duration, family history of cancer, tumor site, stage (early vs advanced), histology, and blood group. GC patients with and without a second tumor were compared in terms of the same clinicopathological features.RESULTS: Of 862 GC patients, 58 (6.7%) developed a total of 62 multiple primary tumors, of which 39 (63%) were metachronous and 23 (37%) synchronous. Four (6.9%) of the 58 multiple GC patients developed two or more neoplasms. The predominant tumor type of the secondary neoplasms was colorectal (n = 17), followed by lung (n = 9), breast (n = 8), and prostate (n = 7). Age was the only clinicopathological feature that differed between GC patients with synchronous vs metachronous malignancies; GC patients with synchronous neoplasms were older than those with metachronous neoplasms (68.0 ± 10.3 years vs 59.9 ± 11.1 years, respectively, P = 0.008). Comparisons between patients with and without a second primary cancer revealed that the only statistically significant differences were in age and blood group. The mean age of the patients with multiple GC was higher than that of those without a second primary tumor (63.4 ± 11.4 years vs 59.5 ± 13.0 years, respectively, P = 0.026). GC patients with a second primary tumor were more commonly blood group O than those without (56.2% vs 31.6%, respectively, P = 0.002).CONCLUSION: GC patients may develop other primary cancers; appropriate preoperative and postoperative diagnostic modalities are thus required, particularly if patients are older and blood group O.  相似文献   
117.

Aims/hypothesis

Fetal programming plays an important role in the pathogenesis of type 2 diabetes. The aim of the present study was to investigate whether maternal metabolic changes during OGTT influence fetal brain activity.

Methods

Thirteen healthy pregnant women underwent an OGTT (75 g). Insulin sensitivity was determined by glucose and insulin measurements at 0, 60 and 120 min. At each time point, fetal auditory evoked fields were recorded with a fetal magnetoencephalographic device and response latencies were determined.

Results

Maternal insulin increased from a fasting level of 67?±?25 pmol/l (mean ± SD) to 918?±?492 pmol/l 60 min after glucose ingestion and glucose levels increased from 4.4?±?0.3 to 7.4?±?1.1 mmol/l. Over the same time period, fetal response latencies decreased from 297?±?99 to 235?±?84 ms (p?=?0.01) and then remained stable until 120 min (235?±?84 vs 251?±?91 ms, p?=?0.39). There was a negative correlation between maternal insulin sensitivity and fetal response latencies 60 min after glucose ingestion (r?=?0.68, p?=?0.02). After a median split of the group based on maternal insulin sensitivity, fetuses of insulin-resistant mothers showed a slower response to auditory stimuli (283?±?79 ms) than those of insulin-sensitive mothers (178?±?46 ms, p?=?0.03).

Conclusions/interpretation

Lower maternal insulin sensitivity is associated with slower fetal brain responses. These findings provide the first evidence of a direct effect of maternal metabolism on fetal brain activity and suggest that central insulin resistance may be programmed during fetal development.  相似文献   
118.
Backgroundβ2-Adrenergic receptor agonists are widely used agents in the treatment of asthma or preterm labor. Since prevalence of asthma was shown to be higher in patients with epilepsy and modulation of noradrenergic system activity may modify epilepsy course, the aim of the present study was to examine the effect of salbutamol (SALB), one of the most commonly used β2-adrenergic receptor agonist on the anticonvulsant potency of four classical antiepileptic drugs (AEDs): valproate (VPA), carbamazepine (CBZ), phenytoin (DPH) and phenobarbital (PB) in mice subjected to the maximal electroshock (MES)-induced seizures.MethodsSeizures were caused by a current delivered through ear-clip electrodes. The influence of AEDs and SALB on animals’ motor coordination and memory processes was also evaluated.ResultsSingle SALB injection did not change, whereas 7 days SALB administration decreased seizure threshold in the MES-induced seizures in mice. Moreover, SALB injected ip for 1 day and for 7 days lowered the antiepileptic activity of PB in the MES-induced seizures in mice, but did not change the effect of other analyzed AEDs: VPA, CBZ or DPH. Butoxamine, a selective β2-adrenergic receptor antagonist, reversed SALB influence on the activity of PB. SALB given alone or in combination with the tested AEDs did not affect animals’ motor performance and memory after both single and 7 days administration.ConclusionsPresented results show that SALB may decrease the antiepileptic efficacy of PB. A special caution is advised to patients with epilepsy receiving β2-adrenergic receptors agonists in the pharmacotherapy of pulmonary and obstetrical disorders.  相似文献   
119.
BackgroundAutoimmune (Hashimoto’s thyroiditis) is characterized by a strong female preponderance, which may suggest that sex hormones have an impact on thyroid autoimmunity. The aim of this study was to investigate whether testosterone determines vitamin D action on thyroid antibody titers and thyroid function tests in men with autoimmune thyroiditis and low testosterone levels.MethodsThe study included 36 men with testosterone deficiency, 17 of whom had been treated for at least 26 weeks with oral testosterone undecanoate (120 mg daily). Because of coexistent euthyroid Hashimoto’s thyroiditis, all participants were then treated with vitamin D (100 μg daily). Serum titers of thyroid peroxidase and thyroglobulin antibodies, serum levels of thyrotropin, free thyroid hormones, testosterone and 25-hydroxyvitamin D, as well as Jostel’s thyrotropin index, SPINA-GT and SPINA-GD were assessed before vitamin D treatment and 26 weeks later.ResultsWith the exception of testosterone levels, there were no significant differences between both study groups in serum hormone levels, antibody titers and thyroid function tests. All participants completed the study. In addition to increasing 25-hydroxyvitamin D levels, vitamin D increased SPINA-GT and reduced thyroid peroxidase and thyroglobulin antibody titers. In testosterone-treated men, vitamin D increased testosterone levels. Vitamin D did not affect serum levels of thyrotropin, free thyroid hormones, Jostel’s thyrotropin index and SPINA-GD. Treatment-induced changes in thyroid antibody titers and SPINA-GT were more pronounced in testosterone-treated than testosterone-naïve men.ConclusionsThe obtained results suggest that the beneficial effect on thyroid autoimmunity and thyroid secretory function is stronger in men receiving testosterone therapy.  相似文献   
120.
High‐quality systematic reviews (SR) and meta‐analyses (MA) are considered to be reliable sources of information. This study aims to assess the quality of studies published as SR or MA in the field of bariatrics in 2016 and 2017. We identified SR and MA in the field of bariatrics by searching electronic databases (MEDLINE, Embase, and Cochrane Database of Systematic Reviews). Eligible studies were those identified as SR/MA in the title/abstract, which aimed to assess any outcome in patients with morbid obesity undergoing or scheduled to undergo bariatric surgery. Two authors independently reviewed all titles and abstracts, assessed full texts of potentially eligible studies, and assessed the quality of included studies. Any discrepancies were resolved by the third reviewer. We evaluated the quality and risk of bias of each SR/MA using AMSTAR 2 checklist and ROBIS tool, respectively. Seventy‐eight of 4236 references met inclusion criteria and were assessed for their quality/risk of bias. The methodological quality of 99% of all papers was classified as “critically low.” A total of 6% of the studies were at low risk of bias, and 78% were assessed as being at high risk of bias. The methodological quality of studies published in 2016 and 2017 as SR/MA is highly unsatisfactory.  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