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   48005篇
  免费   3513篇
  国内免费   192篇
耳鼻咽喉   581篇
儿科学   1001篇
妇产科学   966篇
基础医学   6639篇
口腔科学   1052篇
临床医学   4762篇
内科学   10101篇
皮肤病学   1084篇
神经病学   4593篇
特种医学   1968篇
外国民族医学   2篇
外科学   8626篇
综合类   480篇
一般理论   76篇
预防医学   2674篇
眼科学   948篇
药学   2803篇
  6篇
中国医学   75篇
肿瘤学   3273篇
  2024年   162篇
  2023年   508篇
  2022年   939篇
  2021年   1765篇
  2020年   1084篇
  2019年   1345篇
  2018年   1523篇
  2017年   1026篇
  2016年   1201篇
  2015年   1379篇
  2014年   1870篇
  2013年   2178篇
  2012年   3553篇
  2011年   3502篇
  2010年   1948篇
  2009年   1727篇
  2008年   2729篇
  2007年   2791篇
  2006年   2589篇
  2005年   2411篇
  2004年   2225篇
  2003年   2038篇
  2002年   1861篇
  2001年   526篇
  2000年   521篇
  1999年   540篇
  1998年   431篇
  1997年   341篇
  1996年   257篇
  1995年   250篇
  1994年   211篇
  1993年   219篇
  1992年   369篇
  1991年   339篇
  1990年   308篇
  1989年   272篇
  1988年   265篇
  1987年   244篇
  1986年   234篇
  1985年   262篇
  1984年   216篇
  1983年   205篇
  1982年   169篇
  1981年   159篇
  1980年   170篇
  1979年   182篇
  1978年   151篇
  1977年   137篇
  1976年   135篇
  1974年   142篇
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
11.
12.
13.
14.
Modulation of reactive oxygen and nitrogen species in a tumor could be exploited for nanotherapeutic benefits. We investigate the antitumor effect in Walker-256 carcinosarcoma of magnetic nanodots composed of doxorubicin-loaded Fe3O4 nanoparticles combined with electromagnetic fields. Treatment using the magnetic nanodot with the largest hysteresis loop area (3402 erg/g) had the greatest antitumor effect with the minimum growth factor 0.49 ± 0.02 day–1 (compared to 0.58 ± 0.02 day–1 for conventional doxorubicin). Electron spin resonance spectra of Walker-256 carcinosarcoma treated with the nanodots, indicate an increase of 2.7 times of free iron (that promotes the formation of highly reactive oxygen species), using the nanodot with the largest hysteresis loop area, compared to conventional doxorubicin treatment as well as increases in ubisemiquinone, lactoferrin, NO-FeS-proteins. Hence, we provide evidence that the designed magnetic nanodots can modulate the tumor redox state. We discuss the implications of these results for cancer nanotherapy.  相似文献   
15.
Myasthenia gravis (MG) is an autoimmune disease of the neuromuscular junction. Most patients have pathogenic autoantibodies against the acetylcholine receptor (AChR). In the last years a novel subpopulation of MG patients has been described that harbors antibodies against low-density lipoprotein receptor-related protein 4 (Lrp4), another postsynaptic neuromuscular antigen. In early-onset AChR MG (EOMG), the thymus plays an important role in immunopathogenesis, and early thymectomy is beneficial. It is still unknown if the thymus plays any role in Lrp4-MG. In this pilot study, we compared thymus samples from four patients with Lrp4-MG (one pre-treated with immunosuppressive drugs), four non-MG controls and five EOMG patients (not pretreated with immunosuppressive drugs). Immunohistochemistry of the Lrp4-MG thymi revealed normal architecture, with normal numbers and distribution of B-cells, lymphoid follicles and Hassall's corpuscles. Primary CD23+ lymphoid follicles were similarly infrequent in Lrp4-MG and control thymic sections. In none of the control or Lrp4-MG thymi did we find secondary follicles with CD10+ germinal centers. These were evident in 2 of the 5 EOMG thymi, where primary lymphoid follicles were also more frequent on average, thus showing considerable heterogeneity between patients. Even if characteristic pathological thymic changes were not observed in the Lrp4 subgroup, we cannot exclude a role for the thymus in Lrp4-MG pathogenesis, since one Lrp4-MG patient went into clinical remission after thymectomy alone (at one year follow-up) and one more improved after thymectomy in combination with immunosuppressive therapy.  相似文献   
16.
17.
18.
19.
Small molecule pharmacological inhibition of dominant human genetic disease is a feasible treatment that does not rely on the development of individual, patient‐specific gene therapy vectors. However, the consequences of protein inhibition as a clinical therapeutic are not well‐studied. In advance of human therapeutic trials for CAPN5 vitreoretinopathy, genetic inactivation can be used to infer the effect of protein inhibition in vivo. We created a photoreceptor‐specific knockout (KO) mouse for Capn5 and compared the retinal phenotype to both wild‐type and an existing Capn5 KO mouse model. In humans, CAPN5 loss‐of‐function (LOF) gene variants were ascertained in large exome databases from 60,706 unrelated subjects without severe disease phenotypes. Ocular examination of the retina of Capn5 KO mice by histology and electroretinography showed no significant abnormalities. In humans, there were 22 LOF CAPN5 variants located throughout the gene and in all major protein domains. Structural modeling of coding variants showed these LOF variants were nearby known disease‐causing variants within the proteolytic core and in regions of high homology between human CAPN5 and 150 homologs, yet the LOF of CAPN5 was tolerated as opposed to gain‐of‐function disease‐causing variants. These results indicate that localized inhibition of CAPN5 is a viable strategy for hyperactivating disease alleles.  相似文献   
20.
Purpose

Alterations in immunological homeostasis induced by acute exercise have been frequently reported. In view of the growing amount of repetitive exercise stimuli in competitive sports, quick recovery plays a superior role. Therefore, we examined whether aqua cycling affects cellular immunological recovery.

Methods

After performing 300 countermovement jumps with maximal effort male sport students (n = 20; 24.4 ± 2.2 years) were randomized into either an aqua cycling (AC) or a passive recovery (P) group. AC pedaled in chest-deep water without resistance, while P lay in a supine position. Each recovery protocols lasted 30 min. Blood samples were taken at Baseline, Post-exercise, Post-recovery and 1 h (h), 2 h, 4 h, 24 h, 48 h and 72 h after recovery. Outcomes comprised white blood cell (WBC) counts, lymphocyte (LYM) counts and LYM subsets (CD4/CD8 ratio). Additionally, cellular inflammation markers (neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR) and systemic immune-inflammation index (SII)) were calculated.

Results

In both groups, WBC, NLR and SII were significantly increased compared to Baseline up to and including 4 h after recovery. Significant interaction effects were found for WBC (Post-recovery, 2 h and 4 h), NLR (Post-recovery), SII (Post-recovery) and CD4/CD8 ratio (2 h) with values of AC being higher than of P.

Conclusions

Interestingly, AC provoked a stronger but not prolonged immunological disturbance than P. NLR and SII may present simple, more integrative markers to screen exercise-induced alterations in immune homeostasis/recovery in athletes and clinical populations. More research is warranted to elucidate the clinical and practical relevance of these findings.

  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