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   44900篇
  免费   3836篇
  国内免费   3100篇
耳鼻咽喉   355篇
儿科学   710篇
妇产科学   633篇
基础医学   5576篇
口腔科学   720篇
临床医学   5957篇
内科学   7411篇
皮肤病学   475篇
神经病学   2782篇
特种医学   1465篇
外国民族医学   17篇
外科学   4906篇
综合类   6786篇
现状与发展   5篇
一般理论   7篇
预防医学   2710篇
眼科学   1214篇
药学   4459篇
  31篇
中国医学   1857篇
肿瘤学   3760篇
  2024年   140篇
  2023年   670篇
  2022年   1714篇
  2021年   2188篇
  2020年   1597篇
  2019年   1541篇
  2018年   1607篇
  2017年   1377篇
  2016年   1290篇
  2015年   1923篇
  2014年   2403篇
  2013年   2178篇
  2012年   3227篇
  2011年   3457篇
  2010年   2081篇
  2009年   1709篇
  2008年   2355篇
  2007年   2408篇
  2006年   2240篇
  2005年   2252篇
  2004年   1530篇
  2003年   1478篇
  2002年   1255篇
  2001年   1112篇
  2000年   1126篇
  1999年   1241篇
  1998年   687篇
  1997年   750篇
  1996年   551篇
  1995年   499篇
  1994年   440篇
  1993年   316篇
  1992年   370篇
  1991年   329篇
  1990年   273篇
  1989年   256篇
  1988年   237篇
  1987年   199篇
  1986年   172篇
  1985年   133篇
  1984年   76篇
  1983年   82篇
  1982年   57篇
  1981年   65篇
  1980年   37篇
  1979年   45篇
  1978年   27篇
  1977年   24篇
  1976年   20篇
  1974年   18篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Background and objectives: Vitamin D and folate are highly UV sensitive, and critical for maintaining health throughout the lifecycle. This study examines whether solar irradiance during the first trimester of pregnancy influences vitamin D receptor (VDR) and nuclear folate gene variant occurrence, and whether affected genes influence late-life biochemical/clinical phenotypes.Methodology: 228 subjects were examined for periconceptional exposure to solar irradiance, variation in vitamin D/folate genes (polymerase chain reaction (PCR)), dietary intake (food frequency questionnaire (FFQ)) and important adult biochemical/clinical phenotypes.Results: Periconceptional solar irradiance was associated with VDR-BsmI (P = 0.0008wk7), TaqI (P = 0.0014wk7) and EcoRV (P = 0.0030wk6) variant occurrence between post-conceptional weeks 6–8, a period when ossification begins. Similar effects were detected for other VDR gene polymorphisms. Periconceptional solar irradiance was also associated with 19 bp del-DHFR (P = 0.0025wk6), and to a lesser extent C1420T-SHMT (P = 0.0249wk6), a folate-critical time during embryogenesis. These same genes were associated with several late-life phenotypes: VDR-BsmI, TaqI and ApaI determined the relationship between dietary vitamin D and both insulin (P < 0.0001/BB, 0.0007/tt and 0.0173/AA, respectively) and systolic blood pressure (P = 0.0290/Bb, 0.0299/Tt and 0.0412/AA, respectively), making them important early and late in the lifecycle. While these and other phenotype associations were found for the VDR variants, folate polymorphism associations in later-life were limited to C1420T-SHMT (P = 0.0037 and 0.0297 for fasting blood glucose and HbA1c levels, respectively). We additionally report nutrient–gene relationships with body mass index, thiol/folate metabolome, cognition, depression and hypertension. Furthermore, photoperiod at conception influenced occurrence of VDR-Tru9I and 2R3R-TS genotypes (P = 0.0120 and 0.0360, respectively).Conclusions and implications: Findings identify environmental and nutritional agents that may interact to modify gene–phenotype relationships across the lifecycle, offering new insight into human ecology. This includes factors related to both disease aetiology and the evolution of skin pigmentation.  相似文献   
992.
993.
Interleukin (IL)-27 is a novel cytokine secreted by stimulation of antigen-presenting cells. No previous studies currently reported the role of IL-27 in the carcinogenesis of osteosarcoma. We aimed to investigate the association of IL-27 polymorphisms and serum IL-27p28 with osteosarcoma risk in a Chinese population.One hundred and sixty osteosarcoma patients and 250 health controls were selected. IL-27 gene -964 A/G, 2905 T/G, and 4730 T/C polymorphisms were determined by using polymerase chain reaction-restriction fragment length polymorphism. Enzyme-linked immunosorbent assay were used to detect serum IL-27p28 levels.The serum IL-27p28 levels were significantly lower in osteosarcoma patients compared with those in controls (P < 0.01). Serum IL-27p28 levels in stages III–IV were lower than those in stages I–II of osteosarcoma (P < 0.05); similar results were also found in patients with metastasis, that is, patients with metastasis have higher IL-27p28 levels than those without metastasis (P < 0.05). There were no associations between genotype and allele frequencies of IL-27 -964 A/G, 2905 T/G, 4730 T/C, and the risk of osteosarcoma (P > 0.05). Stratification analysis also failed to show the associations between -964 A/G, 2905 T/G, and 4730 T/C polymorphisms and the clinical stage and metastasis of osteosarcoma (P > 0.05). Three possible haplotypes (A-964T2905T4730, G-964T2905T4730, and G-964G2905C4730) were identified, but no associations were found between them and the osteosarcoma risk (P > 0.05).This study indicates that the lower serum IL-27p28 levels may be associated with development and progression of osteosarcoma, but IL-27 gene -964 A/G, 2905 T/G, and 4730 T/C polymorphisms and their haplotypes are not associated with osteosarcoma risk.  相似文献   
994.
995.
996.
997.
998.
The physician–patient relationship in China is highly strained. This study examined the professional identity of physicians and their perceptions of the physician–patient relationship against the backdrop of the rise of health consumerism in China. Structured interviews with 29 physicians found that the marketization of medical care and the rise of health consumerism caused physicians to have a conflicted professional identity. The traditional bureaucratic relationship between physicians and patients based on implicit trust was gradually replaced by an arm’s length relationship characterized by self-interest, opportunism, and mistrust. In addition, the transition from physician-centered communication to patient-centered communication in China was tenacious. Theoretical and practical implications of the current study are discussed.  相似文献   
999.
Purpose: This study aimed to report the results of endoureterotomy for benign ureteral strictures using the holmium: yttrium-aluminum-garnet laser.

Material and methods: Nineteen patients (8 men and 11 women, mean age 51.47 years) underwent holmium: yttrium-aluminum-garnet laser endoureterotomy for benign ureteral strictures (8 proximal, 3 middle, and 8 distal) using semirigid ureteroscopy and 360-μm fibre at 1.2 J/pulse and 10 Hz. After completion of the incision, a 7-Fr double-J ureteral stent was left for 6 weeks. Thereafter, the patients were followed-up by ultrasound and/or intravenous urography at 36 monthly intervals.

Results: Success was defined as the absence of symptoms plus radiographic resolution of obstructions as assessed by diuretic renography and/or intravenous urography. With a mean follow-up of 40.2 months, success was achieved in 10 (52.6%) of the 19 patients. Nine patients developed recurrent strictures and were considered treatment failures. The stricture length and severity of hydronephrosis correlated with successful outcome, but gender, aetiology, side and location of strictures did not predict outcome.

Conclusions: Although endoureterotomy using a holmium: yttrium-aluminum-garnet laser has an equivocal outcome, the procedure is recommended as a safe, less invasive therapeutic option for the initial management of benign ureteral strictures.  相似文献   
1000.
Programmed death 1 (PD-1) is a T cell co-inhibitory receptor with two ligands, PD-L1 and PD-L2. In cancer, this pathway plays a major role in immune resistance in the tumor environment. Blockade of this pathway can enhance antitumor immune responses. This review discusses the preclinical rationale for PD-1 pathway inhibition in advanced renal cell carcinoma and prostate cancer, in addition to the clinical activity and toxicity of the anti-PD-L1 antibody BMS-936559, as well as anti-PD-1 antibodies MK-3475 and BMS-936558.  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