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   29715篇
  免费   1802篇
  国内免费   440篇
耳鼻咽喉   571篇
儿科学   288篇
妇产科学   335篇
基础医学   4814篇
口腔科学   524篇
临床医学   2446篇
内科学   5686篇
皮肤病学   1181篇
神经病学   2207篇
特种医学   2285篇
外科学   3772篇
综合类   109篇
一般理论   7篇
预防医学   975篇
眼科学   644篇
药学   3081篇
中国医学   484篇
肿瘤学   2548篇
  2024年   20篇
  2023年   256篇
  2022年   844篇
  2021年   1182篇
  2020年   640篇
  2019年   900篇
  2018年   1032篇
  2017年   855篇
  2016年   1272篇
  2015年   1723篇
  2014年   1959篇
  2013年   2154篇
  2012年   3000篇
  2011年   2860篇
  2010年   1816篇
  2009年   1428篇
  2008年   1793篇
  2007年   1693篇
  2006年   1431篇
  2005年   1298篇
  2004年   1019篇
  2003年   812篇
  2002年   690篇
  2001年   271篇
  2000年   211篇
  1999年   140篇
  1998年   107篇
  1997年   79篇
  1996年   53篇
  1995年   41篇
  1994年   34篇
  1993年   21篇
  1992年   44篇
  1991年   38篇
  1990年   31篇
  1989年   29篇
  1988年   23篇
  1987年   22篇
  1986年   18篇
  1985年   20篇
  1984年   18篇
  1983年   11篇
  1982年   8篇
  1981年   10篇
  1980年   6篇
  1979年   4篇
  1978年   7篇
  1977年   4篇
  1973年   5篇
  1967年   5篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
Alveolar soft part sarcoma: MR and angiographic findings   总被引:5,自引:5,他引:0  
Suh JS  Cho J  Lee SH  Shin KH  Yang WI  Lee JH  Cho JH  Suh KJ  Lee YJ  Ryu KN 《Skeletal radiology》2000,29(12):680-689
Objective. To present the MR and angiographic findings of alveolar soft part sarcoma (ASPS). Design and patients. MR examinations (12 tumors of 10 patients) of ASPS performed at multiple hospitals were retrospectively reviewed. The tumors were found in the thigh (n=4), lower leg (n=4), femur (n=2, local metastasis), scalp (n=1) and arm (n=1). The MR signal characteristics including signal intensity, homogeneity and signal void of lesions and bony invasion including direct invasion or local metastasis were evaluated. Angiographic findings (n=4) and post-embolotherapy follow-up MR imaging (n=2) findings were also assessed. Results. Local bony metastasis was found in two cases. Seven tumors showed heterogeneous high signal intensity on T1- and T2-weighted images with good enhancement. One tumor had a very high signal on T1-weighted images. Eight tumors (67%) showed numerous signal voids in or near the tumors. All four angiographic studies showed numerous enlarged vessels, arteriovenous shunts and delayed washout. Two cases mimicked arteriovenous malformations on angiographic studies but MR images demonstrated solid soft tissue components as well as tortuous vessels. Conclusions. High signal on T1-weighted image and numerous signal voids are highly suggestive of ASPS, although they are not universal as has been suggested and arteriovenous malformation should be included in the differential diagnosis. Local bony metastases in ASPS were seen in two cases and should be carefully investigated. Received: 12 April 2000 Revision requested: 27 June 2000, 8 August 2000 Revision received: 2 August 2000, 21 August 2000 Accepted: 22 August 2000  相似文献   
83.
84.
AIM: To investigate the incidence of abrupt visual loss and its associated factors, during anti-vascular endothelial growth factor (VEGF) treatment for type 3 neovascularization. METHODS: This retrospective study included 137 eyes that were newly diagnosed with type 3 neovascularization. All eyes were treated with anti-VEGF therapy. Abrupt visual loss was defined as loss of 5 or more lines in best-corrected visual acuity (BCVA) in comparison to the previous visit. The incidence and timing of abrupt visual loss as well as the factors associated with it, were determined. In addition, the BCVA at the final follow-up was compared between the eyes with and those without abrupt visual loss. RESULTS: The mean follow-up period was 42.4±18.9mo after diagnosis, and abrupt visual loss was noted in 22 eyes (16.1%) at a mean of 19.6±13.9mo. Abrupt visual loss was found to be associated with subretinal hemorrhage in 11 eyes (50.0%), development of or increase in the height of pigment epithelial detachment with fluid in 8 eyes (36.4%), and tears in the retinal pigment epithelium in 3 eyes (13.6%). The logarithm of minimum angle of resolution (logMAR) mean BCVA at the final follow-up was 2.07±0.67 (Snellen equivalents: 20/2349) and 1.00±0.55 (20/200) in eyes with and without abrupt visual loss, respectively. BCVA was significantly worse in the eyes with abrupt visual loss (P<0.001). CONCLUSION: Abrupt visual loss is noted in 16.1% of patients with type 3 neovascularization and is associated with poor visual outcome. Additional studies are needed to determine how abrupt visual loss can be prevented.  相似文献   
85.
Grape seed is an important natural bioactive product with various health benefits. Interstitial cells of Cajal (ICCs) are pacemaker cells in the gastrointestinal (GI) tract. The present study investigated the effects of grape seed powder (GSP) on ICC properties and GI motility. GSP depolarized the pacemaker potentials of ICCs in a dose‑dependent manner. Y25130 or SB269970 slightly inhibited GSP‑induced effects. However, Y25130 and SB269970 together completely blocked GSP-induced effects. In the presence of inhibitors of protein kinase C, protein kinase A, or mitogen-activated protein kinase, GSP‑induced ICC depolarization was inhibited. GSP increased the intestinal transit rate in normal mice and in mice with acetic acid-induced GI motility disorder. In addition, the levels of motilin and substance P were elevated after GSP dosing. These results demonstrate that GSP can regulate GI motility, and therefore, it is a potential therapeutic agent for treating GI motility disorders.  相似文献   
86.
Cu2ZnSn(S,Se)4 (CZTSSe) solar cells with low cost and eco-friendly characteristics are attractive as future sources of electricity generation, but low conversion efficiency remains an issue. To improve conversion efficiency, a method of inserting intermediate layers between the CZTSSe absorber film and the Mo back contact is used to suppress the formation of MoSe2 and decomposition of CZTSSe. Among the candidates for the intermediate layer, graphene oxide (GO) and reduced GO have excellent properties, including high-charge mobility and low processing cost. Depending on the type of GO, the solar cell parameters, such as fill factor (FF), were enhanced. Thus, the conversion efficiency of 6.3% was achieved using the chemically reduced GO intermediate layer with significantly improved FF.  相似文献   
87.
ObjectiveWe aimed to explore how nursing students’ adherence to physical distancing, sense of belonging, or resilience may be associated with viral anxiety during the coronavirus disease (COVID-19) era in South Korea. MethodsWe conducted an online survey among nursing students from December 8–10, 2021. The survey gathered participants’ age, sex, grades, living area, and responses to questions on COVID-19. In addition, responses to Stress and Anxiety to Viral Epidemics-6 items (SAVE-6), adherence to physical distancing, Sense of Belonging Instrument, Calling and Vocation Questionnaire, Patient Health Questionnaire-9 items (PHQ-9), and Connor-Davidson Resilience Scale-2 (CD-RISC2) items were gathered. ResultsThe SAVE-6 score was significantly correlated with adherence to physical distancing (r=0.29), PHQ-9 (r=0.26), and CD-RISC2 (r=-0.34, all p<0.01) similar to partial correlation analysis adjusting participants’ group (freshmen and sophomores vs. juniors and seniors). A linear regression analysis revealed that viral anxiety of nursing students was predicted by sex (female, β=0.20, p=0.001), adherence to physical distancing (β=0.25, p<0.001), sense of belonging (β=0.16, p=0.014), and CD-RISC2 score (β=-0.32, p<0.001) (adjusted R2=0.24, F=10.01, p<0.001). ConclusionWe observed that adherence to physical distancing, sense of belonging, and their resilience influenced nursing student’s viral anxiety. An appropriate support system to manage viral anxiety is needed for nursing students during the COVID-19 pandemic.  相似文献   
88.
89.
90.
BACKGROUND/OBJECTIVESZanthoxylum schinifolium is traditionally used as a spice for cooking in East Asian countries. This study was undertaken to evaluate the anti-proliferative potential of ethanol extracts of Z. schinifolium leaves (EEZS) against human bladder cancer T24 cells.MATERIALS/METHODSSubsequent to measuring the cytotoxicity of EEZS, the anti-cancer activity was measured by assessing apoptosis induction, reactive oxygen species (ROS) generation, and mitochondrial membrane potential (MMP). In addition, we determined the underlying mechanism of EEZS-induced apoptosis through various assays, including Western blot analysis.RESULTSEEZS treatment concentration-dependently inhibited T24 cell survival, which is associated with apoptosis induction. Exposure to EEZS induced the expression of Fas and Fas-ligand, activated caspases, and subsequently resulted to cleavage of poly (ADP-ribose) polymerase. EEZS also enhanced the expression of cytochrome c in the cytoplasm by suppressing MMP, following increase in the ratio of Bax:Bcl-2 expression and truncation of Bid. However, EEZS-mediated growth inhibition and apoptosis were significantly diminished by a pan-caspase inhibitor. Moreover, EEZS inhibited activation of the phosphoinositide 3-kinase (PI3K)/Akt pathway, and the apoptosis-inducing potential of EEZS was promoted in the presence of PI3K/Akt inhibitor. In addition, EEZS enhanced the production of ROS, whereas N-acetyl cysteine (NAC), a ROS scavenger, markedly suppressed growth inhibition and inactivation of the PI3K/Akt signaling pathway induced by EEZS. Furthermore, NAC significantly attenuated the EEZS-induced apoptosis and reduction of cell viability.CONCLUSIONSTaken together, our results indicate that exposure to EEZS exhibits anti-cancer activity in T24 bladder cancer cells through ROS-dependent induction of apoptosis and inactivation of the PI3K/Akt signaling pathway.  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