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   2738篇
  免费   190篇
  国内免费   52篇
耳鼻咽喉   14篇
儿科学   120篇
妇产科学   57篇
基础医学   314篇
口腔科学   149篇
临床医学   269篇
内科学   622篇
皮肤病学   45篇
神经病学   154篇
特种医学   214篇
外科学   403篇
综合类   23篇
预防医学   214篇
眼科学   33篇
药学   166篇
中国医学   10篇
肿瘤学   173篇
  2023年   19篇
  2022年   40篇
  2021年   68篇
  2020年   29篇
  2019年   65篇
  2018年   94篇
  2017年   51篇
  2016年   51篇
  2015年   100篇
  2014年   123篇
  2013年   152篇
  2012年   154篇
  2011年   151篇
  2010年   115篇
  2009年   99篇
  2008年   116篇
  2007年   136篇
  2006年   100篇
  2005年   136篇
  2004年   101篇
  2003年   107篇
  2002年   111篇
  2001年   71篇
  2000年   79篇
  1999年   76篇
  1998年   38篇
  1997年   35篇
  1996年   25篇
  1995年   27篇
  1994年   29篇
  1993年   19篇
  1992年   37篇
  1991年   40篇
  1990年   36篇
  1989年   35篇
  1988年   26篇
  1987年   31篇
  1986年   24篇
  1985年   23篇
  1984年   18篇
  1983年   11篇
  1982年   13篇
  1981年   7篇
  1980年   14篇
  1979年   11篇
  1977年   8篇
  1976年   21篇
  1975年   8篇
  1968年   9篇
  1947年   6篇
排序方式: 共有2980条查询结果,搜索用时 15 毫秒
71.
The effects of duodenal distension on forestomach and abomasal motility were investigated in conscious sheep chronically fitted with intraparietal electrodes, a duodenal cannula, and an intracerebroventricular cannula. Duodenal distensions with a balloon inflated with 40 ml (DD40) of water reduced the frequency of forestomach and abomasal contractions by 45 and 32%, respectively, while distension with 80 ml (DD80) induced a total inhibition. Methysergide, a mixed 5HT1-5HT2 antagonist administered intravenously (200 g/kg) or intracerebroventricularly (20 g/kg) suppressed the DD40-induced inhibition and reduced that induced by DD80. Sprioxatrine, a selective 5HT1A antagonist, intravenously (100 g/kg) or intracerebroventricularly (10 g/kg), suppressed the DD40 and DD80-induced inhibition, which was also attenuated by the 5HT2 antagonist ritanserin given intravenously (200 g/kg) or intracerebroventricularly (20 g/kg). Granisetron, a 5HT3 antagonist, injected intravenously (150 g/kg), abolished the effects of DD40 and DD80 while it had no antagonistic action on DD40 and DD80 when given intracerebroventricularly (15 g/kg). It is concluded that in sheep, duodenal distension inhibits forestomach and abomasal motility through 5HT1A and 5HT2 receptors at the level of the central nervous system and 5HT3 receptors located peripherally.This work was presented in part at the First United European Gastroenterology Week, September 25–30, 1992, Athens, Greece.  相似文献   
72.
73.
74.
Pituitary - To evaluate the maternal–fetal outcomes of CAB-induced pregnancies in patients with prolactinoma in a large cohort. The prevalence of tumor growth, miscarriage, preterm, low birth...  相似文献   
75.
The disorders caused by mutations in genes encoding subunits and accessory proteins of cohesin complex are collectively termed as cohesinopathies. The best known cohesinopathy is Cornelia de Lange Syndrome (CdLS), which is a multisystem developmental disorder characterized by facial dysmorphism, limb malformations, growth and cognitive impairment. Mutations in five genes, encoding subunits of the cohesin complex (SMC1A, SMC3, RAD21) and its regulators (NIPBL, HDAC8), are responsible for ~70% of CdLS cases. We describe a 16‐year‐old boy with facial dysmorphism, growth retardation, intellectual disability, hirsutism and small hands, who has a small Supernumerary Marker Chromosome (sSMC) present in mosaic form. sSMC is composed of two duplicated segments encompassing 17 genes including SMC1A gene, at the regions Xp11.22 and Xp11.21q11.1. Clinical comparison between our patient with a previously reported individual with a SMC1A duplication and four male carriers of similar sSMC reported in databases, suggest that they all share clinical features related to cohesinopathies. Although our patient does not have the classical CdLS craniofacial phenotype, he has pre and postnatal growth retardation, intellectual disability and mild musculoskeletal anomalies, features commonly seen in patients with cohesinopathies.  相似文献   
76.
Obese fat pads are frequently undervascularized and hypoxic, leading to increased fibrosis, inflammation, and ultimately insulin resistance. We hypothesized that VEGF-A-induced stimulation of angiogenesis enables sustained and sufficient oxygen and nutrient exchange during fat mass expansion, thereby improving adipose tissue function. Using a doxycycline (Dox)-inducible adipocyte-specific VEGF-A overexpression model, we demonstrate that the local up-regulation of VEGF-A in adipocytes improves vascularization and causes a "browning" of white adipose tissue (AT), with massive up-regulation of UCP1 and PGC1α. This is associated with an increase in energy expenditure and resistance to high fat diet-mediated metabolic insults. Similarly, inhibition of VEGF-A-induced activation of VEGFR2 during the early phase of high fat diet-induced weight gain, causes aggravated systemic insulin resistance. However, the same VEGF-A-VEGFR2 blockade in ob/ob mice leads to a reduced body-weight gain, an improvement in insulin sensitivity, a decrease in inflammatory factors, and increased incidence of adipocyte death. The consequences of modulation of angiogenic activity are therefore context dependent. Proangiogenic activity during adipose tissue expansion is beneficial, associated with potent protective effects on metabolism, whereas antiangiogenic action in the context of preexisting adipose tissue dysfunction leads to improvements in metabolism, an effect likely mediated by the ablation of dysfunctional proinflammatory adipocytes.  相似文献   
77.
78.
The present study reports the Spanish PETHEMA group experience in 31 heavily pretreated relapsed/refractory acute lymphoblastic leukemia (ALL) and lymphoma (LL) patients treated with clofarabine-based regimens. The complete remission (CR) rate was 31% (median CR duration of 3 months [range 2–28]) and the overall survival probability at 1 year was 10% (95%CI 4–16%). Responses were seen in B and T lineage diseases and in patients with adverse cytogenetics. Hematological and infectious grade >3 toxicities were found in 100 and 67% of the patients, respectively, with 7 (23%) treatment-related deaths. Other organ toxicities were infrequent. Clofarabine-based chemotherapy regimens might induce CRs in ALL and LL patients, but hematological toxicity and infections may limit their use in heavily pretreated patients.  相似文献   
79.

OBJECTIVES:

Myeloid-derived suppressor cells contribute to the immunosuppressive microenvironment during tumor development and limit the efficacy of cancer immunotherapy. Identifying myeloid-derived suppressor cells and associated factors is the first step in creating strategies to reverse the suppressive effects of these cells on the immune system.

METHODS:

To induce lung cancer, we administered 2 doses of urethane to BALB/c mice and observed these animals for 120 days. After this period, we evaluated the percentage of myeloid-derived suppressor cells in the blood, lung and bone marrow. The expression of alpha-smooth muscle actin, transforming growth factor-β, Toll-like receptor 2, Toll-like receptor 4, and interleukin-6 was also determined in the lung tissue.

RESULTS:

Myeloid-derived suppressor cells were increased in all evaluated tissues after lung cancer development in association with increased Toll-like receptor 4 expression and decreased interleukin-6 expression in the lung. We observed alpha-smooth muscle actin and transforming growth factor-β expression in lung nodules.

CONCLUSIONS:

We believe that the early diagnosis of cancer through determining the blood levels of myeloid-derived suppressor cells followed by the depletion of these cells should be further investigated as a possible approach for cancer treatment.  相似文献   
80.
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