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   2591篇
  免费   179篇
  国内免费   25篇
耳鼻咽喉   12篇
儿科学   66篇
妇产科学   103篇
基础医学   349篇
口腔科学   72篇
临床医学   264篇
内科学   632篇
皮肤病学   71篇
神经病学   178篇
特种医学   78篇
外科学   256篇
综合类   27篇
一般理论   1篇
预防医学   171篇
眼科学   78篇
药学   154篇
中国医学   14篇
肿瘤学   269篇
  2024年   5篇
  2023年   55篇
  2022年   89篇
  2021年   158篇
  2020年   98篇
  2019年   117篇
  2018年   118篇
  2017年   66篇
  2016年   110篇
  2015年   107篇
  2014年   133篇
  2013年   170篇
  2012年   259篇
  2011年   212篇
  2010年   123篇
  2009年   92篇
  2008年   143篇
  2007年   139篇
  2006年   110篇
  2005年   112篇
  2004年   88篇
  2003年   77篇
  2002年   70篇
  2001年   14篇
  2000年   3篇
  1999年   8篇
  1998年   14篇
  1997年   5篇
  1996年   2篇
  1995年   4篇
  1994年   11篇
  1993年   6篇
  1992年   11篇
  1991年   8篇
  1990年   8篇
  1989年   2篇
  1988年   6篇
  1987年   6篇
  1986年   5篇
  1985年   5篇
  1983年   2篇
  1982年   4篇
  1981年   2篇
  1979年   3篇
  1978年   3篇
  1977年   2篇
  1974年   5篇
  1973年   1篇
  1971年   1篇
  1965年   1篇
排序方式: 共有2795条查询结果,搜索用时 15 毫秒
21.
The ligands for several activating natural killer (NK) cell receptors have not been identified to date. Soluble receptor fusion proteins can be used to stain target cells for the presence of these unidentified ligands. Here, we describe the generation and use of soluble type I NK cell receptor isoleucine-zipper (ILZ) fusion proteins of the immunoglobulin (Ig) superfamily. ILZ-fusion proteins are easy to produce and purify. They form trimeric complexes in solution and display a higher binding avidity than classical immunoglobulin-fusion proteins. ILZ-fusion proteins do not interact with Fc-receptors and can therefore be used to block receptor-ligand interactions in cellular assays. This makes ILZ-fusion proteins a valuable tool to study receptor-ligand interactions in NK cells and other cellular systems.  相似文献   
22.
23.
24.
Objective: To evaluate the effect of prednisolone plus low-dose aspirin (PSL/LDA) in women with autoimmune conditions who were enrolled in an IVF-ET program.

Design: A retrospective clinical study.

Setting: In vitro fertilization unit, Niigata University Hospital, Niigata, Japan.

Patient(s): Three hundred seven women who underwent IVF-ET between January 1996 and December 1997.

Intervention(s): Prednisolone (10 mg/d) and aspirin (81 mg/d) were administered to the women with autoantibodies who chose to participate.

Main Outcome Measure(s): Pregnancy and implantation rates with IVF-ET.

Result(s): Women undergoing IVF who had positive antinuclear antibodies, with or without antiphospholipid antibodies, had significantly lower pregnancy and implantation rates than did women without autoantibodies (14.8% versus 21.7% and 6.8% versus 10.4%, respectively). The administration of PSL/LDA to women with antinuclear antibodies significantly improved the outcome of IVF-ET (40.6% pregnancy rate and 20.3% implantation rate).

Conclusion(s): A high proportion of women who are undergoing IVF-ET have autoantibodies, which are associated with poor IVF outcomes. The administration of PSL/LDA to these women may improve their implantation rate.  相似文献   

25.

Rational

A growing body of evidence illustrates that 5-HT3 receptor antagonist drugs may be of benefit in the treatment of negative symptoms in schizophrenia.

Objective

The objective of this study was to assess the efficacy and tolerability of tropisetron add-on to risperidone on negative symptoms in patients with chronic stable schizophrenia.

Methods

In a double-blind, placebo-controlled 8-week trial, 40 patients with chronic schizophrenia who were stabilized on risperidone were randomized into tropisetron or placebo add-on groups. Psychotic symptoms were measured using the Positive and Negative Syndrome Scale (PANSS) every 2 weeks. Furthermore, extrapyramidal and depressive symptoms as well as side effects were assessed. The primary outcome measure was the difference in change from baseline of negative subscale scores between the two groups at week 8.

Results

Tropisetron resulted in greater improvement of the total PANSS scores [F(1.860,70.699)?=?37.366, p?<?0.001] as well as negative scores [F(2.439,92.675)?=?16.623, p?<?0.001] and general psychopathology [F(1.767,67.158)?=?4.602, p?=?0.017], but not positive subscale scores [F(1.348, 51.218)?=?0.048, p?=?0.893] compared to placebo. In a multiple regression analysis controlling for positive, extrapyramidal, and depressive symptoms, treatment group (standardized β?=??0.640) significantly predicted changes in primary negative symptoms. The side effect profile did not differ significantly between the two groups.

Conclusion

Tropisetron add-on to risperidone improves the primary negative symptoms of patients with chronic stable schizophrenia.  相似文献   
26.

Objectives

To assess the relationship between superior vena cava (SVC) flow and short-term outcome in infants with perinatal asphyxia.

Methods

Infants in sequence born after more than 35 weeks of gestation who had been hospitalized at the NICU and normal neonatal wards of Wakayama Medical University between May 2005 and September 2010 were recruited for this observational cohort study. The study eligibility criterion was the presence of perinatal asphyxia, as evidenced by abnormal fetal heart rate monitoring and an Apgar score of 7 or less at 1 min or need for resuscitation using positive pressure ventilation. SVC flow was measured in the first three days of life by Doppler echocardiography as described by Kluckow and Evans. Short-term outcome was defined as poor if MRI demonstrated bilateral lesions of the basal ganglia and thalamus and/or multicystic encephalomalacia due to hypoxic ischemia.

Results

In the head cooling group, SVC flow in infants with a good outcome was lower than that in infants with a poor outcome at 12 h (36.9 ± 7.7 vs 113.4 ± 42.4 ml/kg/min (p = 0.01)), 24 h (75.2 ± 25.3 vs 155.6 ± 45.7 ml/kg/min (p = 0.03)), and 48 h (92.5 ± 34.2 vs 161.1 ± 46.7 ml/kg/min (p = 0.04)) after birth. SVC flow decreased promptly after introduction of head cooling in infants who had a good outcome, whereas it increased gradually after head cooling in those who had a poor outcome.

Conclusion

We speculate that regulation of brain circulation is disrupted in infants with asphyxia who show a poor outcome.  相似文献   
27.

Ethnopharmacological relevance

The experimental finding of Asian traditional medicine revealed the pharmacological effect of the local application of ghee which was taken from cow butterfat and the rhizomes of Curcuma longa. These materials significantly improved the healing process of the wound. In addition, ancient physicians of Middle East discovered that the powdered rhizomes of Curcuma longa (common turmeric) also had impressive medicinal qualities. Over the centuries, this spice has been used as a pain relieving, anti-inflammatory agent to relieve pain and inflammation in the skin and muscles.

Aim of the study

We decided to mix ghee which was taken from sheep butterfat with the powdered rhizomes of Curcuma longa to formulate a novel cost-benefit material and then, evaluate its potential therapeutic effect on acceleration of surgical wound healing; moreover, this present study was performed to compare the effects of Curcuma longa–ghee formulation and hyaluronic acid on gingival wound healing following surgery.

Materials and methods

Five healthy 3-year-old male beagle dogs were used in this study. They had intact teeth and the clinical and radiographic examination revealed no periodontal disease. Ghee was obtained from the refined sheep butterfat heated to 70 °C mixed with the powdered rhizomes of Curcuma longa and was applied with two different ratios including materials A and B. Randomly, these three materials including hyaluronic acid, materials A and B were applied topically in test regions and then covered with periodontal pack. Histological changes were monitored in days 4 and 7 after operation to evaluate the inflammatory and repair stage of healing process.

Results

We observed significant difference in the inflammatory and repair parameters of the healing process between cases treated with this new formulation and cases of hyaluronic acid application.

Conclusion

The results suggested a positive potential therapeutic effect on surgical wound healing particularly improvement of periodontal treatment consequences after surgery.  相似文献   
28.
The malignant transformation of mature cystic teratoma is rare, thus occurring in only 1-2% of all cases. The most common malignancy arising in mature cystic teratoma is squamous cell carcinoma. Adenocarcinoma occurs with less frequency. We herein present a patient with an ovarian mature cystic teratoma who demonstrated a malignant transformation to well-differentiated adenocarcinoma. Malignant transformation was diagnosed preoperatively by contrast enhanced computed tomography (CT) and magnetic resonance imaging (MRI). Microscopically and immunohistochemically, the adenocarcinoma was considered to have arisen from the ciliated respiratory epithelium. After a 28-month of follow-up period, she remains free of the disease. This is the third reported case of adenocarcinoma arising in the respiratory epithelium of an ovarian mature cystic teratoma. Contrast enhanced CT and MRI are useful for making a preoperative diagnosis and an immunohistochemical study is helpful for defining its origin.  相似文献   
29.
Despite its potential for reducing human suffering, the advancement of human embryonic stem cell research has not been given top priority by the US government, and the scientific community has been engaged in a debate on this issue in the USA and beyond. The central question in this debate is whether the promise of stem cells justifies the destruction of human embryos - mainly embryos that are surplus to the needs of patients undergoing infertility treatment. It is argued here that this debate belongs in the same category as the debates on global warming and evolution, because it has much in common with both. It is conducted with a heavy load of scientifically uninformed views and beliefs and framed largely by an implacable opposition with the aim of creating public confusion and doubt. It is primarily politically motivated and, as is true about the debate on evolution, it is rooted in religion. A human embryo is not a human being or person even if it is deserving of - and receives - respect and extraordinary care in the context of assisted human reproduction. Rather than engaging in a futile debate that clouds the way forward in a vital branch of biology, scientists ought to continue to emphasize the importance of human embryo research.  相似文献   
30.
本文介绍了PACS的涵义、标准和发展,阐述了基于"均衡策略下的服务器集群"的全院级PACS架构设计、特点和实施方案。  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