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   35464篇
  免费   3415篇
  国内免费   1109篇
耳鼻咽喉   696篇
儿科学   685篇
妇产科学   395篇
基础医学   3524篇
口腔科学   545篇
临床医学   3931篇
内科学   4303篇
皮肤病学   448篇
神经病学   2562篇
特种医学   999篇
外国民族医学   10篇
外科学   2110篇
综合类   6549篇
现状与发展   6篇
一般理论   1篇
预防医学   3714篇
眼科学   554篇
药学   3397篇
  41篇
中国医学   4136篇
肿瘤学   1382篇
  2024年   57篇
  2023年   744篇
  2022年   998篇
  2021年   1752篇
  2020年   1749篇
  2019年   1371篇
  2018年   1477篇
  2017年   1459篇
  2016年   1540篇
  2015年   1374篇
  2014年   2673篇
  2013年   2741篇
  2012年   2450篇
  2011年   2422篇
  2010年   1926篇
  2009年   1606篇
  2008年   1614篇
  2007年   1603篇
  2006年   1350篇
  2005年   1202篇
  2004年   1026篇
  2003年   1005篇
  2002年   655篇
  2001年   645篇
  2000年   516篇
  1999年   456篇
  1998年   317篇
  1997年   308篇
  1996年   293篇
  1995年   305篇
  1994年   264篇
  1993年   196篇
  1992年   179篇
  1991年   171篇
  1990年   155篇
  1989年   130篇
  1988年   97篇
  1987年   97篇
  1986年   91篇
  1985年   155篇
  1984年   145篇
  1983年   94篇
  1982年   114篇
  1981年   86篇
  1980年   97篇
  1979年   49篇
  1978年   67篇
  1977年   33篇
  1976年   41篇
  1974年   19篇
排序方式: 共有10000条查询结果,搜索用时 16 毫秒
1.
Continuous utero-placental circulation, and patent umbilical blood vessels ensure an uninterrupted transfer of oxygen and nutrients to the fetus as well as clearance of metabolic waste products. The onset of labour characterized by progressive and strong uterine contractions poses a threat to fetal oxygenation as a result of collapsing the spiral arterioles traversing the myometrium to supply the placental bed, and repetitive compression of the blood vessels within the umbilical cord. Human fetuses are equipped with compensatory mechanisms to cope with transient interruptions of blood supply during labour. The ability to compensate may be blunted in cases of poor fetal reserves, increased metabolic demand (macrosomia or maternal fever), and due to non-hypoxic pathways (e.g. chorioamniontis or fetal hypovolumia-hypotension syndrome). Intrapartum fetal surveillance involves prompt recognition of the features that signal the onset of fetal decompensation on the cardiotocograph (CTG) to ensure a timely intervention to avoid hypoxic-ischaemic encephalopathy (HIE) or perinatal deaths. This article summarises a ‘physiological approach’ to the interpretation of the CTG which, in places, conflicts with other current UK guidance.  相似文献   
2.
3.
Cyclotron-produced copper-64 radioisotope tracers offer the possibility to perform both diagnostic investigation by positron emission tomography (PET) and radiotherapy by a theranostic approach with bifunctional chelators. The versatile chemical properties of copper add to the importance of this isotope in medicinal investigation. [64Cu][Cu (ATSM)] has shown to be a viable candidate for imaging of tumor hypoxia; a critical tumor microenvironment characteristic that typically signifies tumor progression and resistance to chemo-radiotherapy. Various production and radiosynthesis methods of [64Cu][Cu (ATSM)] exist in labs, but usually involved non-standardized equipment with varying production qualities and may not be easily implemented in wider hospital settings. [64Cu][Cu (ATSM)] was synthesized on a modified GE TRACERlab FXN automated synthesis module. End-of-synthesis (EOS) molar activity of [64Cu][Cu (ATSM)] was 2.2–5.5 Ci/μmol (HPLC), 2.2–2.6 Ci/μmol (ATSM-titration), and 3.0–4.4 Ci/μmol (ICP-MS). Radiochemical purity was determined to be >99% based on radio-HPLC. The final product maintained radiochemical purity after 20 h. We demonstrated a simple and feasible process development and quality control protocols for automated cyclotron production and synthesis of [64Cu][Cu (ATSM)] based on commercially distributed standardized synthesis modules suitable for PET imaging and theranostic studies.  相似文献   
4.
PurposeTo assess the safety and tolerability of a vandetanib-eluting radiopaque embolic (BTG-002814) for transarterial chemoembolization (TACE) in patients with resectable liver malignancies.Materials and MethodsThe VEROnA clinical trial was a first-in-human, phase 0, single-arm, window-of-opportunity study. Eligible patients were aged ≥18 years and had resectable hepatocellular carcinoma (HCC) (Child-Pugh A) or metastatic colorectal cancer (mCRC). Patients received 1 mL of BTG-002814 transarterially (containing 100 mg of vandetanib) 7–21 days prior to surgery. The primary objectives were to establish the safety and tolerability of BTG-002814 and determine the concentrations of vandetanib and the N-desmethyl vandetanib metabolite in the plasma and resected liver after treatment. Biomarker studies included circulating proangiogenic factors, perfusion computed tomography, and dynamic contrast-enhanced magnetic resonance imaging.ResultsEight patients were enrolled: 2 with HCC and 6 with mCRC. There was 1 grade 3 adverse event (AE) before surgery and 18 after surgery; 6 AEs were deemed to be related to BTG-002814. Surgical resection was not delayed. Vandetanib was present in the plasma of all patients 12 days after treatment, with a mean maximum concentration of 24.3 ng/mL (standard deviation ± 13.94 ng/mL), and in resected liver tissue up to 32 days after treatment (441–404,000 ng/g). The median percentage of tumor necrosis was 92.5% (range, 5%–100%). There were no significant changes in perfusion imaging parameters after TACE.ConclusionsBTG-002814 has an acceptable safety profile in patients before surgery. The presence of vandetanib in the tumor specimens up to 32 days after treatment suggests sustained anticancer activity, while the low vandetanib levels in the plasma suggest minimal release into the systemic circulation. Further evaluation of this TACE combination is warranted in dose-finding and efficacy studies.  相似文献   
5.
BackgroundPrior to dolutegravir availability, ritonavir-boosted lopinavir (LPV/r) was an alternative recommendation when first-line drugs could not be used. A high concentration of protease inhibitors was observed in the Thai people living with HIV (PLWH). Thus, dose reduction of LPV/r may be possible. However, the pharmacokinetics and dose optimization of LPV/r have never been investigated. This study aimed to develop a population pharmacokinetic model of LPV/r and provide dosage optimization in Thai PLWH.MethodsLPV and RTV trough concentrations from Thai PLWH were combined with intensive data. The data were analyzed by the nonlinear mixed-effects modeling approach. The influence of RTV concentration on LPV oral clearance (CL/F) was investigated.ResultsRifampicin (RIF) use increased LPV and RTV CL/F by 2.16-fold and 1.99-fold, respectively. The reduced dose of 300/75 and 200/150 mg twice daily provided a comparable percentage of patients achieving LPV target trough concentration to the standard dose for PI-naïve patients. For HIV/TB co-infected patients receiving RIF who could not tolerate the recommended dose, the reduced dose of 600/150 mg twice daily was recommended.ConclusionThe population pharmacokinetic model was developed by integrating the interaction between LPV and RTV. The reduced LPV/r dosage offers sufficient LPV exposure for Thai PLWH.  相似文献   
6.
ObjectivesTo review the evidence pertaining to the association between cow’s milk protein allergy and recurrent acute otitis media and otitis media with effusion.MethodsThe CENTRAL, Web of Science, EMBASE, MEDLINE, LILACS databases, and gray literature were searched.ResultsFour studies were included, identifying the prevalence rates: 0.2% of delayed speech due to chronic otitis media with effusion in 382 children with cow’s milk protein allergy, 10.7% of cow’s milk protein allergy in 242 children who underwent ENT procedures, 40% of cow’s milk protein allergy in 25 children with recurrent otitis media with effusion and higher tendency to otitis media in children with cow’s milk protein allergy of 186 children (1.5 + 0.6 vs. 0.4 + 0.1; p < 0.1).ConclusionConsidering the characteristics and methodological variations of the identified studies, it is not possible to state that there is reliable evidence of an association between cow’s milk protein allergy and otitis media.  相似文献   
7.
BackgroundIn order to avoid excessive treatment of thyroid nodules in the clinic, it is necessary to find a simple and practical analysis method to comprehensively and accurately reflect benign or malignant thyroid nodules. This study aimed to construct and validate a comprehensive and reliable network-based predictive model using a variety of imaging and laboratory criteria for thyroid nodules to stratify the risk of malignancy prior to surgery.MethodsWe retrospectively analyzed data from patients who underwent surgical treatment for thyroid nodules at the Thyroid and Breast Diagnosis and Treatment Center of Weifang Hospital of Traditional Chinese Medicine between January 2018 and December 2020. Binary logical regression analysis was performed to predict whether nodules were malignant or benign. The developmental dataset included 457 patients (January 2018–December 2020). The validation set included separate data points (n = 225, January 2018–December 2020).ResultsIn this study, criteria that showed significant predictive value for malignant nodules included TI-RADS: 4b (p = 0.065); Bethesda IV, Bethesda V, Bethesda VI (P < 0.0001); BRAFV600E mutation (P < 0.0001); Calcitonin>5 pg/ml (p = 0.0037); and FNA-Tg>30 ng/ml (p = 0.0003). A 10-grade risk scoring system was developed. The risk of malignancy risk ranged from 2.06% to 100% and was positively associated with increasing risk grade. The areas under the receiver-operating characteristic curve of the development and validation sets were 0.972 and 0.946, respectively.ConclusionA simple, comprehensive and reliable web-based predictive model was designed using a variety of imaging and laboratory criteria to stratify thyroid nodules by probability of malignancy.  相似文献   
8.
王育光  刘志威 《肝脏》2022,27(1):38-41
目的通过信息化随访方式干预慢性乙型病毒性肝炎患者,对比分析其对患者疾病及用药依从性影响。方法收集2014年10月至2017年10月惠州市第六人民医院门诊及住院部诊断为慢性乙型病毒性肝炎、乙肝肝硬化患者,剔除不符合纳入条件患者,共纳入符合条件患者264例,有42例合并肝硬化。对纳入患者采取分层随机抽样方法进行分组,最终微信+电话随访组87例,电话随访组88例,对照组89例。随访并对比三组在2年后肝功能、肝硬化人数及停用恩替卡韦时间等不同差异。结果随访年后三组在失访人数上差异存在统计学意义,其中A组与B组2年后两组在ALT(Z=-3.218,P=0.02)、AST(Z=-2.749,P=0.03)、Alb(Z=1.746,P=0.04)、乙肝病毒DNA(Z=-3.231,P=0.02)指标差异具有统计学意义,而TBil、FIB-4指数、APRI、γ-GT指标差异无统计学意义。A组与C组2年后对比结果显示,两组在ALT(Z=-11.089,P<0.001)、AST(Z=-9.247,P=0.01)、TBil(Z=-7.623,P=0.01)、APRI(Z=-4.834,P=0.01)、γ-GT(Z=-2.867,P=0.03)、Alb(Z=3.187,P=0.02)、乙肝病毒DNA(Z=-10.078,P<0.001)指标差异具有统计学意义,而FIB-4指数指标差异无统计学意义。B组与C组2年后两组对比结果显示,两组在ALT(Z=-1.275,P=0.04)、AST(Z=-2.045,P=0.03)、TBil(Z=-3.762,P=0.02)、APRI(Z=-1.461,P=0.04)、γ-GT(Z=-2.254,P=0.03)、乙肝病毒DNA(Z=-1.782,P=0.04)指标差异具有统计学意义,而Alb、FIB-4指数指标差异无统计学意义。随访2年后A组肝硬化人数为12人,B组为16人,C组为24人。A组与B组(χ2=0.945,P=0.408)、B组与C组肝硬化人数(χ2=2.741,P=0.103)差异无统计学意义,而A、C两组肝硬化人数差异有统计学意义(χ2=6.843,P=0.013)。在2年时间内,A组有15例患者暂停使用恩替卡韦,B组有28例,C组有61例,三组停用恩替卡韦人数差异有统计学意义(χ2=25.061,P<0.001),通过Kaplan-meier分析,结果显示A组使用恩替卡韦时间长于B组(83.0%vs 68.5%,χ2=5.754,P=0.016)及C组(83.0%vs 33.7%,χ2=61.601,P<0.001),而B组使用时间长于C组(63.5%vs 33.7%,χ2=32.451,P<0.001)。结论通过对患者强化信息化干预,可以使患者服用抗乙肝病毒药物依从性提高,降低患者肝功能异常发生及肝硬化发病率。  相似文献   
9.
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