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   4822篇
  免费   331篇
  国内免费   133篇
耳鼻咽喉   129篇
儿科学   93篇
妇产科学   41篇
基础医学   574篇
口腔科学   77篇
临床医学   469篇
内科学   908篇
皮肤病学   80篇
神经病学   367篇
特种医学   140篇
外科学   577篇
综合类   498篇
现状与发展   2篇
一般理论   3篇
预防医学   321篇
眼科学   54篇
药学   403篇
中国医学   128篇
肿瘤学   422篇
  2024年   10篇
  2023年   37篇
  2022年   113篇
  2021年   182篇
  2020年   103篇
  2019年   120篇
  2018年   128篇
  2017年   116篇
  2016年   112篇
  2015年   191篇
  2014年   218篇
  2013年   244篇
  2012年   420篇
  2011年   407篇
  2010年   281篇
  2009年   225篇
  2008年   313篇
  2007年   329篇
  2006年   311篇
  2005年   281篇
  2004年   205篇
  2003年   215篇
  2002年   202篇
  2001年   77篇
  2000年   61篇
  1999年   53篇
  1998年   43篇
  1997年   36篇
  1996年   24篇
  1995年   24篇
  1994年   25篇
  1993年   25篇
  1992年   28篇
  1991年   14篇
  1990年   14篇
  1989年   14篇
  1988年   13篇
  1987年   12篇
  1986年   9篇
  1985年   3篇
  1984年   4篇
  1983年   5篇
  1977年   3篇
  1976年   5篇
  1973年   3篇
  1970年   3篇
  1968年   4篇
  1965年   2篇
  1962年   2篇
  1926年   2篇
排序方式: 共有5286条查询结果,搜索用时 17 毫秒
101.
ObjectivesIt was previously shown that dehydroepiandrosterone (DHEA) reverses chronic hypoxia-induced pulmonary hypertension (PH) in rats, but whether DHEA can improve the clinical and hemodynamic status of patients with PH associated to chronic obstructive pulmonary disease (PH-COPD) has not been studied whereas it is a very severe poorly treated disease.Patients and methodsEight patients with PH-COPD were treated with DHEA (200 mg daily orally) for 3 months. The primary end-point was the change in the 6-minute walk test (6-MWT) distance. Secondary end-points included pulmonary hemodynamics, lung function tests and tolerance of treatment.ResultsThe 6-MWT increased in all cases, from 333 m (median [IQR]) (257; 378) to 390 m (362; 440) (P < 0.05). Mean pulmonary artery pressure decreased from 26 mmHg (25; 27) to 21.5 mmHg (20; 25) (P < 0.05) and pulmonary vascular resistance from 4.2 UI (3.5; 4.4) to 2.6 UI (2.5; 3.8) (P < 0.05). The carbon monoxide diffusing capacity of the lung (DLCO % predicted) increased significantly from 27.4% (20.1; 29.3) to 36.4% (14.6; 39.6) (P < 0.05). DHEA treatment did not change respiratory parameters of gas exchange and the 200 mg per day of DHEA used was perfectly tolerated with no side effect reported.ConclusionDHEA treatment significantly improves 6-MWT distance, pulmonary hemodynamics and DLCO of patients with PH-COPD, without worsening gas exchange, as do other pharmacological treatments of PH (trial registration NCT00581087).  相似文献   
102.
103.
Hypertension, one of the major cardiovascular risk factors, promotes the formation of atheromatous lesions in the large arteries, including the aorta. It also favors aortic aneurysm and acute aortic syndrome such as aortic dissection or hematoma. In patients with aortic disease, beta-blockers and/or renin-angiotensin-aldosterone system inhibitors should be preferentially used to decrease blood pressure and improve arterial wall properties.  相似文献   
104.
This study examined the association of host genetic variants with the antibody response to the quadrivalent meningococcal conjugate vaccine (MCV4) in HIV-infected youth. Genetic variants associated with severity of meningococcal disease, including the IgG Fc receptor (FCγRII)-A484T, interleukin-10 (IL-10)-A1082G, -C819T, and -C627A, IL-4-C589T, mannose binding lectin-2 (MBL2)-A/O, -H/L, -P/Q, and -X/Y, toll-like receptor 2 (TLR2)-G2408A, TLR4-A12874G and -C13174T, and TLR9-T1237C and -T1486C were determined by real-time PCR (RT-PCR) for 271 HIV-infected subjects (median, 17 years). Response was defined as a ≥4-fold increase from entry in bactericidal antibody titers to each serogroup. Generalized estimating equation (GEE) models were used to evaluate the association of allelic variants with the immunologic response to all serogroups within each subject with and without adjusting for CD4 percentage and HIV viral load. At week 4, but not after, subjects with TLR2-2408-G/A versus -G/G genotypes and the TLR4-12874-A/A genotype were more likely to achieve a ≥4-fold increase overall in the four serogroups (unadjusted P of 0.006 and adjusted P of 0.008 and unadjusted P of 0.008 and adjusted P of 0.019, respectively). At week 28, the TLR9-1237 T allele was associated with enhanced antibody response (T allele versus C/C, unadjusted P of 0.014 and adjusted P of 0.009), which was maintained at week 72 (unadjusted and adjusted P of 0.008). At week 72, the FcγRII-131Arg allotype was associated with a ≥4-fold increase in antibody titer versus those with His/His (unadjusted P of 0.009; adjusted P of <0.001). These findings suggest that for HIV-infected youth, the initial antibody response to MCV4 is associated with variants in TLR2 and TLR4 while the long-term response is associated with genetic polymorphisms in TLR9 and FcγRIIa.  相似文献   
105.
Clear cell papillary renal cell carcinoma (CCPRCC) is a recently recognized renal neoplasm, which was initially described in end-stage renal disease (ESRD), but some cases have been reported in otherwise normal kidneys. We report a series of 11 CCPRCC (age range, 33-72 years; male-to-female ratio, 8:3). Follow-up was available for 8 patients. No patients developed local recurrence, distant or lymph-node metastasis, or cancer death. Histologically, all tumors exhibit morphologic features typical of CCPRCC including a mixture of cystic and papillary components, covered by small to medium-sized cuboidal cells with abundant clear cytoplasm. All 11 cases exhibited moderate to strong positivity for CK7, CA9, Vim, and HIF-1α, coupled with negative reactions for CD10, P504S, and RCC. We did not find any VHL gene mutations in all 11 cases. Losses of chromosomes 3 (monoploid chromosome 3) was detected in 3 cases. Ultrastructurally, the tumor cells composed of numerous glycogens with scanty cell organelles, reminiscent of clear cell renal cell carcinoma (CCRCC). In conclusion, the coexpression of CA9 and HIF-1α in the absence of VHL gene abnormalities in CCPRCC suggests activation of the HIF pathway by mechanisms independent of VHL gene mutation. Losses of chromosomes 3 (monosomies chromosome 3) was detected in 3 cases suggesting that at least some of these lesions have demonstrated abnormalities of chromosomes 3. Ultrastructurally, CCPRCC composed of numerous glycogens with scanty cell organelles, reminiscent of CCRCC suggesting the close pathogenesis relationship of CCPRCC with CCRCC.  相似文献   
106.
107.
108.
Selective photocatalytic reduction of CO2 has been regarded as one of the most amazing ways for re-using CO2. However, its application is still limited by the low CO2 conversion efficiency. This work developed a novel Pt/In2O3/g-C3N4 multifunctional catalyst, which exhibited high activity and selectivity to HCOOH during photocatalytic CO2 reduction under visible light irradiation owing to the synergistic effect between photocatalyst, thermocatalyst, and heterojunctions. Both In2O3 and g-C3N4 acted as visible photocatalysts, in which porous g-C3N4 facilitated H2 production from water splitting while the In2O3 nanosheets embedded in g-C3N4 pores favored CO2 fixation and H adsorption onto the Lewis acid sites. Besides, the In2O3/g-C3N4 heterojunctions could efficiently inhibit the photoelectron–hole recombination, leading to enhanced quantum efficiency. The Pt could act as a co-catalyst in H2 production from photocatalytic water splitting and also accelerated electron transfer to inhibit electron–hole recombination and generated a plasma effect. More importantly, the Pt could activate H atoms and CO2 molecules toward the formation of HCOOH. At normal pressure and room temperature, the TON of HCOOH in CO2 conversion was 63.1 μmol g−1 h−1 and could reach up to 736.3 μmol g−1 h−1 at 40 atm.

A multifunctional Pt/In2O3/g-C3N4 catalyst exhibited high activity and selectivity to HCOOH during CO2 reduction owing to the synergy between visible-light harvesting, CO2 activation, HER, and photoelectron–hole separation via heterojunctions.  相似文献   
109.
Research‐based evidence supports the effectiveness of soothing music in improving stress‐related psycho‐physiological indices in a clinical setting. However, there is currently insufficient scientific knowledge of the effects of music on immune markers of stress in humans. Therefore, the aims of the study were to compare the effects of music and quiet rest on the levels of interleukin‐6 (IL‐6), tumour necrosis factor‐α (TNF‐α), interleukin‐10 (IL‐10), heart rate and mean arterial pressure among healthcare workers. By using a randomized controlled trial design, 60 nurses were randomly assigned to the stimulating or sedating music or rest groups for 30 min. Participants' psychoneuroimmunological parameters were measured using enzyme‐linked immunosorbent assays. General estimating equation was used to analyse data. Results revealed that IL‐6, TNF‐α and IL‐10 were not detectable in this population. No significance differences in heart rate were found among the three groups. However, the stimulating music group had significantly higher mean arterial pressure levels than the sedating music group but no differences between the quiet rest group and the sedating music group. Music with different tempi had little effect on mean arterial pressure. Any effect of music on immune markers of stress requires further research. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
110.
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