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   1095篇
  免费   36篇
  国内免费   44篇
耳鼻咽喉   7篇
儿科学   35篇
妇产科学   83篇
基础医学   169篇
口腔科学   15篇
临床医学   129篇
内科学   224篇
皮肤病学   5篇
神经病学   41篇
特种医学   224篇
外科学   46篇
综合类   11篇
预防医学   44篇
眼科学   4篇
药学   77篇
中国医学   2篇
肿瘤学   59篇
  2022年   6篇
  2019年   8篇
  2018年   9篇
  2015年   18篇
  2014年   17篇
  2013年   22篇
  2012年   15篇
  2011年   24篇
  2010年   24篇
  2009年   24篇
  2008年   23篇
  2007年   55篇
  2006年   28篇
  2005年   37篇
  2004年   26篇
  2003年   17篇
  2002年   24篇
  2001年   23篇
  2000年   29篇
  1999年   31篇
  1998年   41篇
  1997年   37篇
  1996年   40篇
  1995年   34篇
  1994年   51篇
  1993年   26篇
  1992年   14篇
  1991年   19篇
  1990年   26篇
  1989年   46篇
  1988年   46篇
  1987年   47篇
  1986年   29篇
  1985年   33篇
  1984年   25篇
  1983年   16篇
  1982年   13篇
  1981年   9篇
  1980年   12篇
  1979年   15篇
  1978年   7篇
  1977年   21篇
  1976年   16篇
  1975年   9篇
  1974年   9篇
  1971年   7篇
  1969年   12篇
  1968年   5篇
  1967年   6篇
  1966年   5篇
排序方式: 共有1175条查询结果,搜索用时 15 毫秒
31.
Hepatic artery infusion (HAI) chemotherapy is associated with higher response rates compared to systemic chemotherapy in those patients with unresectable liver malignancies. Operative hepatic artery catheter (HAC) insertion has significant morbidity and mortality, especially in patients with high‐volume disease, some of whom may not respond to HAI chemotherapy. We report our experience in 45 patients with high‐volume liver disease who were initially treated with HAI chemotherapy via a radiologically placed temporary HAC to try to select the responders who then went on to have an operative HAC. In these 45 patients who had 62 radiologically placed HAC, we found very few major complications, and certainly no complications such as cholecystitis, vascular or malperfusion problems.  相似文献   
32.
Objective: Alendronate and calcitonin are antiresorptive drugs that were used for the treatment of postmenopausal osteoporosis and were shown to increase bone mineral density (BMD). However, the effect of both drugs in daily clinical practice may differ from that observed in clinical trials.Method: About 50 postmenopausal osteoporotic women were observed during their first year of treatment. Among them, 32 patients used alendronate and 18 used calcitonin. Lumbar spine and femoral neck BMD were measured by dual energy X-ray absorptiometry (DXA) at baseline and after 1 year of therapy. Biochemical markers (B-ALP – bone-specific alkaline phosphatase, OTC – osteocalcin and DPD/UCr – deoxypyridinoline/creatinine ratio) of bone metabolism were measured at baseline and 6 months later. Patient compliance was assumed by tablet counting and verified at interview. Each patient was further questioned about her attitude towards the treatment, as well as her dairy product intake, physical activity, use of other medications, smoking and social status.Main outcome measure: (1) Annual percent change in BMD in lumbar spine and femoral neck after the one-year treatment with either alendronate or calcitonin. (2) The change in biochemical markers of bone turnover.Results: The lumbar spine BMD significantly increased by 7.0% (P < 0.001), the femoral neck BMD by 4.3% (P < 0.01). OTC, B-ALP and DPD/UCr decreased significantly during the therapy with alendronate. Compliance with therapy was 79% (95% CI 68–90%). In the calcitonin-treated group, the lumbar spine BMD significantly increased by 3.1 % (P < 0.05), while the femoral neck BMD remained unchanged. OTC, B-ALP and DPD/UCr did not change significantly during the treatment with calcitonin. Compliance with calcitonin therapy was 87% (95% CI 63–110%). The annual change of BMD in both treatment groups was independent on all questioned factors.Conclusion: In daily practice, alendronate enhanced significantly BMD both in lumbar spine and femoral neck. Calcitonin showed increase only in the lumbar spine BMD.  相似文献   
33.
34.
35.
BackgroundNeurotrophins, especially brain-derived neurotrophic factor (BDNF) have gained significant therapeutic interest particularly in neurologic and psychiatric disorders and they have been found in human breast milk of mothers who suffered from adverse outcomes in pregnancy. This study tested the hypothesis that oral administration of BDNF/GDNF (glial cell line-derived neurotrophic factor) can exert a biological effect in a rat model of severe neuropathology induced by olfactory bulbectomy (OBX), which exhibits dysregulation of BDNF signaling and impaired blood-brain barrier.MethodsAdult male albino Sprague-Dawley rats underwent the OBX surgery and separate groups of OBX and sham-operated controls received one oral dose of vehicle, BDNF (0.005 mg/kg), GDNF (0.03 mg/kg) or their combination. One week after neurotrophin dosing the rats were sacrificed and BDNF level was assessed by ELISA in the blood serum and cerebrospinal fluid.ResultsA significant decrease of serum BDNF level was found in the OBX model. This alteration was normalized by all types of treatment BDNF, GDNF, or their combination. No influence of sham surgery or treatment was observed in the control rats. BDNF levels in cerebrospinal fluid were below detection limit.ConclusionThis study indicates that oral administration of neurotrophins is able to exert a biological effect in the OBX model. There is a number of potential mechanisms, which remain to be elucidated.  相似文献   
36.
We have evaluated the fibrinogen/fibrin fragment E antigen assay as a diagnostic test in patients with clinically suspected venous thrombosis by comparing the results of this assay with venography in 272 patients. The result of the fragment E antigen assay was elevated in 79 of 80 patients with positive venograms for recent venous thrombosis (sensitivity 99%) and within the normal range in 161 of 192 patients with normal venograms (specificity 84%). The fragment E assay was also evaluated in 130 medical and surgical controls without evidence of venous thrombosis by leg scanning and the test was found to be relatively nonspecific. However, in the patient group under study, a correct clinical diagnosis of no thrombosis, based on a normal fragment E result, was made in 161 of 162 cases (negative predictive value of 99%). Therefore, a normal test result effectively excludes a diagnosis of venous thrombosis in clinically symptomatic patients. The assay, as currently performed, is technically demanding and takes 24 hr to complete. Therefore, it will have to be simplified before it can be applied to clinical practice.  相似文献   
37.

Background:

Monoamine reuptake inhibitors exhibit unique clinical profiles that reflect distinct engagement of the central nervous system (CNS) transporters.

Methods:

We used a translational strategy, including rodent pharmacokinetic/pharmacodynamic modeling and positron emission tomography (PET) imaging in humans, to establish the transporter profile of TD-9855, a novel norepinephrine and serotonin reuptake inhibitor.

Results:

TD-9855 was a potent inhibitor of norepinephrine (NE) and serotonin 5-HT uptake in vitro with an inhibitory selectivity of 4- to 10-fold for NE at human and rat transporters. TD-9855 engaged norepinephrine transporters (NET) and serotonin transporters (SERT) in rat spinal cord, with a plasma EC50 of 11.7ng/mL and 50.8ng/mL, respectively, consistent with modest selectivity for NET in vivo.Accounting for species differences in protein binding, the projected human NET and SERT plasma EC50 values were 5.5ng/mL and 23.9ng/mL, respectively. A single-dose, open-label PET study (4–20mg TD-9855, oral) was conducted in eight healthy males using the radiotracers [11C]-3-amino-4- [2-[(di(methyl)amino)methyl]phenyl]sulfanylbenzonitrile for SERT and [11C]-(S,S)-methylreboxetine for NET. The long pharmacokinetic half-life (30–40h) of TD-9855 allowed for sequential assessment of SERT and NET occupancy in the same subject. The plasma EC50 for NET was estimated to be 1.21ng/mL, and at doses of greater than 4mg the projected steady-state NET occupancy is high (>75%). After a single oral dose of 20mg, SERT occupancy was 25 (±8)% at a plasma level of 6.35ng/mL.

Conclusions:

These data establish the CNS penetration and transporter profile of TD-9855 and inform the selection of potential doses for future clinical evaluation.  相似文献   
38.
CD11b is the alpha chain of the Mac-1 integrin and is preferentially expressed in myeloid cells (neutrophils, monocytes, and macrophages). We have previously shown that the CD11b promoter directs cell-type- specific expression in myeloid lines using transient transfection assays. To confirm that these promoter sequences contain the proper regulatory elements for correct myeloid expression of CD11b in vivo, we have used the -1.7-kb human CD11b promoter to direct reporter gene expression in transgenic mice. Stable founder lines were generated with two different reporter genes, a Thy 1.1 surface marker and the Escherichia coli lacZ (beta-galactosidase) gene. Analysis of founders generated with each reporter demonstrated that the CD11b promoter was capable of driving high levels of transgene expression in murine macrophages for the lifetime of the animals. Similar to the endogenous gene, transgene expression was preferentially found in mature monocytes, macrophages, and neutrophils and not in myeloid precursors. These experiments indicate that the -1.7 CD11b promoter contains the regulatory elements sufficient for high-level macrophage expression. This promoter should be useful for targeting heterologous gene expression to mature myeloid cells.  相似文献   
39.
胃癌组织中MVD和VEGF表达与影像学表现的关系   总被引:2,自引:2,他引:2  
  相似文献   
40.
Mucinous carcinomas represent a distinct morphological subtype which can arise from several organ sites, including the ovary, and their genetic characteristics are largely under‐described. Exome sequencing of 12 primary mucinous ovarian tumours identified RNF43 as the most frequently somatically mutated novel gene, secondary to KRAS and mutated at a frequency equal to that of TP53 and BRAF. Further screening of RNF43 in a larger cohort of ovarian tumours identified additional mutations, with a total frequency of 2/22 (9%) in mucinous ovarian borderline tumours and 6/29 (21%) in mucinous ovarian carcinomas. Seven mutations were predicted to truncate the protein and one missense mutation was predicted to be deleterious by in silico analysis. Six tumours had allelic imbalance at the RNF43 locus, with loss of the wild‐type allele. The mutation spectrum strongly suggests that RNF43 is an important tumour suppressor gene in mucinous ovarian tumours, similar to its reported role in mucinous pancreatic precancerous cysts. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.  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