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   18288篇
  免费   988篇
  国内免费   83篇
耳鼻咽喉   133篇
儿科学   402篇
妇产科学   249篇
基础医学   2323篇
口腔科学   475篇
临床医学   1272篇
内科学   4474篇
皮肤病学   897篇
神经病学   1276篇
特种医学   464篇
外科学   3269篇
综合类   71篇
一般理论   1篇
预防医学   488篇
眼科学   384篇
药学   1172篇
中国医学   45篇
肿瘤学   1964篇
  2023年   85篇
  2022年   207篇
  2021年   334篇
  2020年   191篇
  2019年   258篇
  2018年   354篇
  2017年   307篇
  2016年   346篇
  2015年   311篇
  2014年   446篇
  2013年   497篇
  2012年   777篇
  2011年   827篇
  2010年   572篇
  2009年   456篇
  2008年   750篇
  2007年   836篇
  2006年   907篇
  2005年   926篇
  2004年   866篇
  2003年   825篇
  2002年   797篇
  2001年   663篇
  2000年   670篇
  1999年   640篇
  1998年   207篇
  1997年   158篇
  1996年   174篇
  1995年   131篇
  1994年   97篇
  1993年   116篇
  1992年   413篇
  1991年   356篇
  1990年   380篇
  1989年   398篇
  1988年   359篇
  1987年   322篇
  1986年   317篇
  1985年   272篇
  1984年   213篇
  1983年   161篇
  1979年   144篇
  1978年   104篇
  1977年   105篇
  1974年   104篇
  1973年   79篇
  1972年   96篇
  1971年   83篇
  1970年   87篇
  1969年   69篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Objectives: We assessed the impact of musculoskeletal diseases, depressive mental state, and hypertension on locomotive syndrome, a condition of reduced mobility requiring nursing care. Since locomotive syndrome is a major public health issue that needs attention, its relationship with functional inconvenience in performing daily activities was also investigated.

Methods: We conducted a cross-sectional study using an Internet panel survey, comprising 747 persons aged 30–90 years. Demographics, personal medical history, and daily activity data were assessed. The 25-question Geriatric Locomotive Function Scale was used to diagnose locomotive syndrome. Stepwise linear regression analysis and logistic regression analysis were conducted to evaluate the association between locomotive syndrome, musculoskeletal diseases, and functional inconvenience.

Results: Aging, osteoporosis, and low back pain significantly increased the risk of locomotive syndrome, followed by knee osteoarthritis and lumbar spinal stenosis. Locomotive syndrome was significantly related to depressive mental state and hypertension, and led to functional inconvenience in Seiza sitting, cleaning, shopping, and strolling.

Conclusion: Locomotive syndrome was associated with functional inconvenience in performing common daily activities involving the lower extremities and spine. Osteoporosis and aging were significantly associated with locomotive syndrome. The risk of locomotive syndrome may be decreased by treating comorbid osteoporosis and instituting exercise and diet-related modifications.  相似文献   

2.
Chlorogenic acid (CGA) is a polyphenol found in coffee and medicinal herbs such as Lonicera japonica. In this study, the effect of CGA-induced relaxation on carbachol (CCh)-induced contraction of mouse urinary bladder was investigated. CGA (30–300 μg/ml) inhibited CCh- or U46619-induced contraction in a concentration-dependent manner. SQ22536 (adenylyl cyclase inhibitor) recovered CGA-induced relaxation of CCh-induced contraction; however, ODQ (guanylyl cyclase inhibitor) did not have the same effect. In addition, 3-isobutyl-1-methylxanthine (IBMX) enhanced CGA-induced relaxation; however, forskolin or sodium nitroprusside did not have the same effect. Moreover, Ro 20–1724, a selective phosphodiesterase (PDE) 4 inhibitor, enhanced CGA-induced relaxation, but vardenafil, a selective PDE5 inhibitor, did not have the same effect. In the presence of CCh, CGA increased cyclic adenosine monophosphate (cAMP) level, whereas SQ22536 inhibited the increase of cAMP levels. Moreover, higher cAMP levels were obtained with CGA plus IBMX treatment than the total cAMP levels obtained with separate CGA and IBMX treatments. In conclusion, these results suggest that CGA inhibited CCh-induced contraction of mouse urinary bladder by partly increasing cAMP levels via adenylyl cyclase activation.  相似文献   
3.
4.
European Journal of Applied Physiology - This study examined the effect of different knee flexion angles with a constant hip and knee torque on the muscle force and neuromuscular activity of the...  相似文献   
5.
6.
The purpose of this study was to determine the viability of Tongue Coating Index, which is a new method for evaluating tongue-coating status. To determine the reliability and reproducibility of our new evaluation criteria (Score 0: Tongue coating not visible; Score 1: Tongue coating thin, papillae of tongue visible; Score 2: Tongue coating very thick, papillae of tongue not visible), 10 observers evaluated 20 photographs of tongues. Each tongue surface was divided into nine sections. Observers evaluated each section according to our new criteria and each score for tongue-coating status was recorded in the pertinent section of the Tongue Coating Record form. They repeated the same evaluation 2 weeks after the first evaluation. The relationship between the scores obtained and number of oral microorganisms was investigated in 50 edentulous patients. Tongue coating was collected from the tongue surface after evaluation of tongue-coating status. The total number of anaerobic bacteria and the number of Candida species were counted from the specimens collected. Interobserver agreement and intraobserver agreement were 0.66 and 0.80 by Cohen's kappa, respectively. No significant difference was observed in the number of Candida species among the three scores. The number of total anaerobic bacteria, however, was significantly different among the scores (P < 0.05). Therefore, we conclude that our method for evaluating tongue-coating status offers new criteria that are superior in reliability and reproducibility, and that also reflect the total number of anaerobic bacteria present on the dorsum of the tongue.  相似文献   
7.
In this study, the effects of pulsed Nd:YAG laser irradiation on the apical seat and periapical region of instrumented root canals were investigated. One hundred and ninety-two teeth, including incisors and molars (239 root canals), in 18 healthy adult beagle dogs were used. After extirpation of the pulp under anaesthesia, each root canal was shaped up to at least a size 40 K-file, and then laser irradiated using the following parameters: 1 W, 15 pps for 2, 3, and 4 s; 2 W, 15 pps for 2 s. The effectiveness of debris removal and carbonization on the root canal walls immediately laser irradiation were examined and inflammation of the periapical region at 1, 2, and 4 weeks after laser irradiation was examined using light microscopy. Effective debris removal was observed in most cases in the laser-treated groups and was dependent on irradiated energy. Carbonization was observed in the irradiated root canals except at the parameter of 1 W for 2 s. Periapical inflammation was observed at 1 W for 2 s to the same extent as in the control group (P > 0.01). These results suggest that the pulsed Nd:YAG laser is useful for debris removal with no adverse effects immediately after extirpation of the pulp if appropriate parameters are selected.  相似文献   
8.
The plasminogen activator (PA)-plasmin proteolytic system has recently received considerable attention because of its participation in a wide variety of biological activities and in pathological conditions involving tissue destruction. Excessive mechanical stress such as occlusal trauma is associated with alveolar bone loss in severe periodontitis. Therefore, mechanical stress may involve degradation of the extracellular matrix by occlusal trauma through activation of the PA-plasmin proteolytic system. We examined the effects of mechanical stress on PA activity, gene expressions of tissue type (t) PA, urokinase type (u) PA and PA inhibitor-1 (PAI-1) in human PDL cells. Human PDL cells were cultured on flexible-bottomed culture plates and placed on a Flexercell Strain Unit. The cells were flexed at 6 cycles (5 s strain, 5 s relaxation) at 9% and 18% elongation for 5 d. Application of tension-force induced significantly higher PA activity in stressed PDL cells than in non-stressed controls, and did so in a time- and magnitude-dependent manner (p<0.001, ANOVA). Western-blot analysis revealed that the high level of activity was due to tPA and not uPA. Gene expression of tPA mRNA in stressed PDL cells, as examined by RT-PCR, increased on d 5. These findings suggest that tPA may be involved in periodontal metabolism in response to mechanical stress.  相似文献   
9.
OBJECTIVE: In orthodontic tooth movement, some cytokines released from periodontal ligament fibroblasts and alveolar bone osteoblasts on the pressure side can alter the normal processes of bone remodelling, resulting in physiological bone resorption. We examined the effect of compressive force and interleukin (IL)-1 type I receptor antagonist (IL-1ra) on the expression of inflammatory cytokines that promote osteoclast formation, as well as on their receptors, in osteoblastic Saos-2 cells. DESIGN: The cells were cultured in Dulbecco's modified Eagle medium containing 10% fetal bovine serum with or without continuous compressive force (0.5-3.0 g/cm(2)) and/or IL-1ra for up to 24h. The gene expression levels of the cytokines and their receptors were estimated by determining mRNA levels using real-time PCR; the protein levels were determined using ELISA or immunohistochemical staining. RESULTS: The expression of IL-1beta, IL-1 receptor, IL-6, IL-6 receptor, IL-8 receptor, IL-11 and tumor necrosis factor-alpha (TNFalpha) increased depending on the strength and duration of the compressive force, whereas the expression of IL-8, IL-11 receptor and TNFalpha receptor did not change with the application of compressive force. The expression of cytokines and their receptors produced by 3.0 g/cm(2) of compressive force decreased with the simultaneous addition of IL-1ra and the decrease was remarkable in IL-8 receptor, IL-11 and TNFalpha. CONCLUSION: These results indicate that mechanical stress induces the production of inflammatory cytokines and their receptors in osteoblasts and the phenomenon is enhanced by the autocrine action of IL-1beta, which is increased in amount by mechanical stress.  相似文献   
10.
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