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   6648篇
  免费   409篇
  国内免费   89篇
耳鼻咽喉   91篇
儿科学   137篇
妇产科学   117篇
基础医学   1153篇
口腔科学   110篇
临床医学   555篇
内科学   1251篇
皮肤病学   133篇
神经病学   489篇
特种医学   488篇
外科学   817篇
综合类   50篇
预防医学   205篇
眼科学   231篇
药学   606篇
中国医学   125篇
肿瘤学   588篇
  2023年   45篇
  2022年   137篇
  2021年   212篇
  2020年   113篇
  2019年   189篇
  2018年   254篇
  2017年   142篇
  2016年   256篇
  2015年   324篇
  2014年   419篇
  2013年   414篇
  2012年   680篇
  2011年   604篇
  2010年   386篇
  2009年   319篇
  2008年   439篇
  2007年   381篇
  2006年   347篇
  2005年   278篇
  2004年   227篇
  2003年   222篇
  2002年   216篇
  2001年   58篇
  2000年   45篇
  1999年   29篇
  1998年   61篇
  1997年   48篇
  1996年   42篇
  1995年   22篇
  1994年   33篇
  1993年   15篇
  1992年   14篇
  1991年   15篇
  1990年   12篇
  1989年   22篇
  1988年   18篇
  1987年   12篇
  1986年   13篇
  1985年   12篇
  1983年   7篇
  1982年   5篇
  1981年   10篇
  1980年   5篇
  1979年   4篇
  1978年   4篇
  1977年   6篇
  1974年   4篇
  1970年   4篇
  1967年   3篇
  1962年   3篇
排序方式: 共有7146条查询结果,搜索用时 15 毫秒
31.
Rationale:Transvaginal evisceration of the small bowel is an extremely rare condition after hysterectomy, which requires urgent surgical intervention to prevent serious bowel morbidity and mortality.Patient concerns:A 65-year-old woman presented with sudden-onset severe abdominal pain and a mass protruding through the vagina. The past surgical history was significant, with an abdominal hysterectomy for cervical cancer performed 11 weeks prior to presentation.Diagnosis:Pelvic examination revealed prolapsed small-bowel loops (18-20 cm in length). Pelvic computed tomography scan confirmed the presence of transvaginal evisceration of the small bowel.Interventions:Bowel reduction and urgent laparotomy were the selected treatment approaches for a detailed inspection and thorough washing of the intrα-abdominal cavity. A Foley catheter was inserted in the emergency room, with the subject in the lithotomy position. The prolapsed bowel loops spontaneously reduced without manual reduction, and the vault defect was repaired transvaginally.Outcomes:The patient experienced no postoperative complications and remained disease-free for 9months postoperatively.Lessons:Transvaginal evisceration of the small bowel should be considered a surgical emergency. A multidisciplinary approach to prompt case management involving clinicians in gynecology, general surgery, and emergency medicine is vital for preventing serious consequences. Hysterectomy is the most frequently performed gynecological surgical procedure, and evisceration occurs most often after hysterectomy. Therefore, patients should be informed about this rare but possible hysterectomy complication.  相似文献   
32.
A lignan, (+)-isolariciresinol, was isolated fromRubia akane Nakai. This is the first reporting from Rubiaceae.  相似文献   
33.
The oncogenic PI3K/Akt/mammalian target of rapamycin (mTOR) signaling axis and its downstream effector, the ribosomal protein S6 kinase 1 (S6K1) play a key role in mediating cell survival in various tumor cells. Here, we investigated the effects of brassinin (BSN), a phytoalexin first identified as a constituent of cabbage, on the PI3K/Akt/mTOR/S6K1 activation, cellular proliferation, and apoptosis in PC‐3 human prostate cancer. BSN exerted a significant dose‐dependent cytotoxicity and reduced constitutive phosphorylation of Akt against androgen‐independent PC‐3 cells as compared to androgen‐dependent LNCaP cells. Moreover, knockdown of androgen receptor (AR) by small interfering RNA enhanced the potential effect of BSN on induction of apoptosis in LNCaP cells. BSN clearly suppressed the constitutive activation of PI3K/Akt/mTOR/S6K1 signaling cascade, which correlated with the induction of apoptosis as characterized by accumulation of cells in subG1 phase, positive Annexin V binding, TUNEL staining, loss of mitochondrial membrane potential, down‐regulation of antiapoptotic and proliferative proteins, activation of caspase‐3, and cleavage of PARP. Additionally, BSN could block broad‐spectrum inhibition of PI3K/Akt/mTOR/S6K1 axes, and aberrant Akt activation by pcDNA3‐myr‐HA‐Akt1 plasmid could not prevent the observed suppressive effect of BSN on constitutive mTOR activation. Finally, overexpression of Bcl‐2 also attenuated BSN‐mediated apoptosis in PC‐3 cells. Taken together, our findings suggest that BSN can interfere with multiple signaling cascades involved in tumorigenesis and might be provided as a potential therapeutic candidate for both the prevention and treatment of prostate cancer. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   
34.
35.
The present study was designed to investigate whether the aqueous extract of rhubarb (AR) could prevent the development of atherosclerosis through regulating vascular inflammatory processes in rats fed with an atherogenic diet. AR significantly reduced plasma low-density lipoprotein-cholesterol, and increased plasma high-density lipoprotein-cholesterol in rats fed with an atherogenic diet. AR inhibited vascular expressions of endothelin-1 (ET-1) and endothelin-converting enzyme (ECE) induced in rats with an atherogenic diet. On the other hand, AR augmented the vascular expression of endothelial nitric oxide synthase (ecNOS) and restored vascular nitric oxide (NO) production. Furthermore, AR suppressed the elevated expression of vascular nuclear factor-kappaB (NF-kappaB) p65 as well as adhesion molecules, including intracellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin in rats fed with an atherogenic diet. Also, AR decreased endothelial expression of ICAM-1 and ET-1 in aorta. These results suggest that AR suppresses the development of atherosclerosis in the atherogenic-diet rat model through inhibiting vascular expressions of proinflammatory and adhesion molecules via the regulation of nitric oxide and endothelin system.  相似文献   
36.
37.
Optimal management of indoor air quality in an enclosed swine house, especially in winter, is indispensable for preventing the transmission of infectious respiratory disease to workers and animals. Studies are needed to elucidate the correlation of aerial contaminants and climate factors. It was observed that indoor air contamination in an enclosed pig building was the highest at 2:00--5:00 PM, followed by 8:00--11:00 PM and 8:00--11:00 AM. It was assumed that this was attributed to the increase of swine activities in the afternoon. In general, the concentration of total dust and total airborne bacteria in an enclosed pig building was found to have a significant correlation with temperature and relative humidity (P<0.05). There were significant correlations between total dust and total airborne bacteria, between total dust and ammonia, and between total dust and odor at the 95% confidence level. In conclusion, temperature and total dust concentration correlated significantly with all parameters except hydrogen sulfide (H(2)S). This could have been due to the drying of swine feces due to the increase in interior temperature and the resuspension of feed deposited on the floor of the pig building by the swines' activity, resulting in a high generation of dust that adsorbed and carried the airborne bacteria and odorous compounds in the enclosed pig building. It was proved that an adsorptive capacity of dust for ammonia was higher than for hydrogen sulfide.  相似文献   
38.
BackgroundAsthma and chronic obstructive pulmonary disease (COPD) are airway diseases with similar clinical manifestations, despite differences in pathophysiology. Asthma-COPD overlap (ACO) is a condition characterized by overlapping clinical features of both diseases. There have been few reports regarding the prevalence of ACO in COPD and severe asthma cohorts. ACO is heterogeneous; patients can be classified on the basis of phenotype differences. This study was performed to analyze the prevalence of ACO in COPD and severe asthma cohorts. In addition, this study compared baseline characteristics among ACO patients according to phenotype.MethodsPatients with COPD were prospectively enrolled into the Korean COPD subgroup study (KOCOSS) cohort. Patients with severe asthma were prospectively enrolled into the Korean Severe Asthma Registry (KoSAR). ACO was defined in accordance with the updated Spanish criteria. In the COPD cohort, ACO was defined as bronchodilator response (BDR) ≥ 15% and ≥ 400 mL from baseline or blood eosinophil count (BEC) ≥ 300 cells/μL. In the severe asthma cohort, ACO was defined as age ≥ 35 years, smoking ≥ 10 pack-years, and post-bronchodilator forced expiratory volume in 1 s/forced vital capacity < 0.7. Patients with ACO were divided into four groups according to smoking history (threshold: 20 pack-years) and BEC (threshold: 300 cells/μL).ResultsThe prevalence of ACO significantly differed between the COPD and severe asthma cohorts (19.8% [365/1,839] vs. 12.5% [104/832], respectively; P < 0.001). The percentage of patients in each group was as follows: group A (light smoker with high BEC) – 9.1%; group B (light smoker with low BEC) – 3.7%; group C (moderate to heavy smoker with high BEC) – 73.8%; and group D (moderate to heavy smoker with low BEC) – 13.4%. Moderate to heavy smoker with high BEC group was oldest, and showed weak BDR response. Age, sex, BDR, comorbidities, and medications significantly differed among the four groups.ConclusionThe prevalence of ACO differed between COPD and severe asthma cohorts. ACO patients can be classified into four phenotype groups, such that each phenotype exhibits distinct characteristics.  相似文献   
39.
For the long‐term efficacy of dry eye disease treatment, relieving underlying inflammation is necessary. Imatinib mesylate is a novel ophthalmic formulation of imatinib mesylate, which is expected to alleviate inflammation by inhibiting the discoidin domain receptor 1 activity. This study aims to evaluate the safety and pharmacokinetics of imatinib mesylate in healthy subjects. A randomized, double‐blind, placebo‐controlled study was conducted. In a single ascending dose, 16 subjects received a single eye drop of imatinib mesylate 0.1%, 0.3%, or matching placebo. In the multiple ascending dose (MAD), subjects received multiple eye drops of imatinib mesylate 0.1%, 0.3%, or matching placebo once daily for 7 days. Safety and tolerability were assessed by ophthalmic examination, including the visual analog scale (VAS) to monitor the burning sensation in the eyes. A total of four treatment‐emergent adverse events (TEAEs) occurred during the study. All TEAEs were mildly severe with no serious cases. VAS results in the 0.1% MAD group exhibited highest score of two points, whereas it was less than one point in others. Insignificant difference between the imatinib mesylate and placebo groups in the VAS results was seen. After a single dose administration of imatinib mesylate 0.1%, all plasma concentrations were below the lower limit of quantification. The peak plasma concentrations of imatinib were less than 0.54 µg/L in all groups. In conclusion, a single and multiple topical ophthalmic administration of imatinib mesylate was well‐tolerated in healthy subjects. Because there was minimal systemic exposure to imatinib, the adverse effect in the body seems to be insignificant.  相似文献   
40.
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