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   4599篇
  免费   284篇
  国内免费   28篇
耳鼻咽喉   44篇
儿科学   137篇
妇产科学   129篇
基础医学   794篇
口腔科学   75篇
临床医学   465篇
内科学   851篇
皮肤病学   157篇
神经病学   549篇
特种医学   148篇
外科学   328篇
综合类   46篇
一般理论   3篇
预防医学   349篇
眼科学   72篇
药学   398篇
中国医学   43篇
肿瘤学   323篇
  2023年   37篇
  2022年   95篇
  2021年   210篇
  2020年   107篇
  2019年   166篇
  2018年   146篇
  2017年   107篇
  2016年   152篇
  2015年   147篇
  2014年   212篇
  2013年   252篇
  2012年   432篇
  2011年   455篇
  2010年   254篇
  2009年   172篇
  2008年   341篇
  2007年   315篇
  2006年   269篇
  2005年   240篇
  2004年   201篇
  2003年   171篇
  2002年   157篇
  2001年   33篇
  2000年   21篇
  1999年   38篇
  1998年   31篇
  1997年   18篇
  1996年   10篇
  1995年   12篇
  1994年   14篇
  1993年   6篇
  1992年   5篇
  1991年   5篇
  1990年   5篇
  1988年   3篇
  1987年   3篇
  1986年   4篇
  1985年   3篇
  1984年   5篇
  1983年   4篇
  1982年   4篇
  1981年   5篇
  1980年   4篇
  1979年   5篇
  1978年   6篇
  1977年   3篇
  1975年   4篇
  1974年   5篇
  1971年   3篇
  1934年   2篇
排序方式: 共有4911条查询结果,搜索用时 62 毫秒
991.

Background  

There is strong, internationally confirmed evidence for the short-term effectiveness of multimodal interdisciplinary specific treatment programs for chronic back pain. However, the verification of long-term sustainability of achieved effects is missing so far. For long-term improvement of pain and functional ability high intervention intensity or high volume seems to be necessary (> 100 therapy hours). Especially in chronic back pain rehabilitation, purposefully refined aftercare treatments offer the possibility to intensify positive effects or to increase their sustainability. However, quality assured goal-conscious specific aftercare programs for the rehabilitation of chronic back pain are absent.  相似文献   
992.
993.
An aluminum (Al) matrix with various transition metal (TM) additions is an effective alloying approach for developing high-specific-strength materials for use at elevated temperatures. Conventional fabrication processes such as casting or fusion-related methods are not capable of producing Al–TM alloys in bulk form. Solid phase processing techniques, such as extrusion, have been shown to maintain the microstructure of Al–TM alloys. In this study, extrusions are fabricated from gas-atomized aluminum powders (≈100–400 µm) that contain 12.4 wt % TM additives and an Al-based matrix reinforced by various Al–Fe–Cr–Ti intermetallic compounds (IMCs). Two different extrusion techniques, conventional hot extrusion and friction extrusion, are compared using fabricating rods. During extrusion, the strengthening IMC phases were extensively refined as a result of severe plastic deformation. Furthermore, the quasicrystal approximant IMC phase (70.4 wt % Al, 20.4 wt % Fe, 8.7 wt % Cr, 0.6 wt % Ti) observed in the powder precursor is replaced by new IMC phases such as Al3.2Fe and Al45Cr7-type IMCs. The Al3Ti-type IMC phase is partially dissolved into the Al matrix during extrusion. The combination of linear and rotational shear in the friction extrusion process caused severe deformation in the powders, which allowed for a higher extrusion ratio, eliminated linear voids, and resulted in higher ductility while maintaining strength comparable to that resulting from hot extrusion. Results from equilibrium thermodynamic calculations show that the strengthening IMC phases are stable at elevated temperatures (up to ≈ 600 °C), thus enhancing the high-temperature strength of the extrudates.  相似文献   
994.
995.
ObjectiveTo investigate the diabetic therapeutic potentiality and antioxidative efficacy of ethyl acetate fraction of hydro-methanol (40:60) extract of root of Musa paradisiaca Lam. (Musaceae) in streptozotocin-induced diabetic rat.MethodsStreptozotocin-induced diabetic state was confirmed by decreased serum insulin level and carbohydrate metabolomics i.e. increased fasting blood glucose level, glycated hemoglobin level and diminished glycogen contents in liver and skeletal muscle. Reproductive homeostasis alteration in diabetes was evaluated by reproductive organo-somatic indices, sperm count, motility and histological analysis of testicular seminiferous tubule along with levels of serum testosterone, testicular cholesterol and seminal vesicular fructose assessment. Oxidative stress in primary and accessory sex organs, and in sperm pellet was assessed by measuring antioxidant enzyme activities along with quantification of free radicals products. Testicular pro-apoptotic Bax-α mRNA expression pattern was studied semi-quantitatively by PCR technique. Reverse phase HPLC fingerprinting was performed using methanol and acetonitrile as mobile phase.ResultsOral administration of ethyl acetate fraction at a dose of 20 mg/0.5 mL of distilled water/100 gm body weight twice daily to the diabetic rats for 28 days significantly recovered organo-somatic indices, protected reproductive activities, corrected oxidative stress markers and pro-apoptotic mRNA expression pattern, which were deviated in diabetes mellitus from control level without any type of toxicity. HPLC fingerprinting shows five completely resolved peaks at γ max 254 nm and 342 nm.ConclusionsIt has a promising antihyperglycaemic and antioxidative activity for curing diabetes induced reproductive disorders in streptozotocin-induced diabetic rat.  相似文献   
996.
International Journal of Legal Medicine - Biomechanical load and hormonal levels tended to change just like the soft and skeletal tissue of the elderly with age. Although aging in both sexes shared...  相似文献   
997.
998.
Although the role of sentinel lymph node biopsy (SLNB) as a prognostic factor is well established, its consequences for therapy are controversial. The aim of this study was to analyze if complete lymph node dissection (CLND) in patients with more than one positive sentinel lymph node (SLN) significantly improves melanoma‐specific survival (MSS) and progression‐free survival (PFS). Medical records of patients who underwent SLNB between 2001 and 2016 at the University Hospital of Cologne were reviewed, and patients with positive SLN were identified. Patient and tumor characteristics, patterns of recurrence, progression‐free and melanoma‐specific survival were analyzed. Seventy‐eight patients with multiple positive and 197 patients with one positive SLN were included in this study. Patients with multiple positive SLN had significantly more positive non‐SLN compared with patients with only one positive SLN (26.9% vs 8.6%, P = 0.01). However, in the subgroup of patients with multiple positive SLN, CLND did not significantly improve MSS (mean MSS 95 vs 75 months, P = 0.5) and PFS (mean PFS 59 vs 68 months P = 0.167). CLND did not result in a significant improvement in PFS and MSS in patients with multiple positive SLN.  相似文献   
999.
1000.
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