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   142470篇
  免费   18001篇
  国内免费   10333篇
耳鼻咽喉   1641篇
儿科学   1359篇
妇产科学   1941篇
基础医学   11938篇
口腔科学   1617篇
临床医学   19870篇
内科学   18898篇
皮肤病学   1597篇
神经病学   6206篇
特种医学   4707篇
外国民族医学   76篇
外科学   17506篇
综合类   38443篇
现状与发展   34篇
一般理论   3篇
预防医学   7055篇
眼科学   3697篇
药学   14049篇
  336篇
中国医学   8703篇
肿瘤学   11128篇
  2024年   600篇
  2023年   4213篇
  2022年   8086篇
  2021年   9599篇
  2020年   9337篇
  2019年   5169篇
  2018年   4936篇
  2017年   3823篇
  2016年   4889篇
  2015年   6986篇
  2014年   12385篇
  2013年   11245篇
  2012年   15047篇
  2011年   15243篇
  2010年   10331篇
  2009年   8386篇
  2008年   6377篇
  2007年   8066篇
  2006年   6054篇
  2005年   3831篇
  2004年   3000篇
  2003年   2445篇
  2002年   1933篇
  2001年   1814篇
  2000年   1400篇
  1999年   1316篇
  1998年   792篇
  1997年   766篇
  1996年   403篇
  1995年   336篇
  1994年   232篇
  1993年   286篇
  1992年   281篇
  1991年   220篇
  1990年   264篇
  1989年   160篇
  1988年   131篇
  1987年   170篇
  1986年   120篇
  1985年   71篇
  1984年   39篇
  1983年   22篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Podophyllotoxin (PPT) exhibited significant activity against P-glycoprotein mediated multidrug resistant (MDR) tumor cell lines; however, due to its poor solubility and high toxicity, PPT cannot be dosed systemically, preventing its clinical use for MDR cancer. We developed a nanoparticle dosage form of PPT by covalently conjugating PPT and polyethylene glycol (PEG) with acetylated carboxymethyl cellulose (CMC-Ac) using one-pot esterification chemistry. The polymer conjugates self-assembled into nanoparticles (NPs) of variable sizes (20–120 nm) depending on the PPT-to-PEG molar ratio (2–20). The conjugate with a low PPT/PEG molar ratio of 2 yielded NPs with a mean diameter of 20 nm and released PPT at ∼5%/day in serum, while conjugates with increased PPT/PEG ratios (5 and 20) produced bigger particles (30 nm and 120 nm respectively) that displayed slower drug release (∼2.5%/day and ∼1%/day respectively). The 20 nm particles exhibited 2- to 5-fold enhanced cell killing potency and 5- to 20-fold increased tumor delivery compared to the larger NPs. The biodistribution of the 20 nm PPT-NPs was highly selective to the tumor with 8-fold higher accumulation than all other examined tissues, while the larger PPT-NPs (30 and 120 nm) exhibited increased liver uptake. Within the tumor, >90% of the 20 nm PPT-NPs penetrated to the hypovascular core, while the larger particles were largely restricted in the hypervascular periphery. The 20 nm PPT-NPs displayed significantly improved efficacy against MDR tumors in mice compared to the larger PPT-NPs, native PPT and the standard taxane chemotherapies, with minimal toxicity.  相似文献   
82.
83.
狼疮抗凝物是发生静脉血栓栓塞症的危险因素之一,在静脉血栓栓塞症患者中检测狼疮抗凝物,对治疗方案抉择和疗效预后判断等方面具有重要意义。目前尚无相关文献对狼疮抗凝物检测在静脉血栓栓塞症中的应用进展进行分析总结,为加深对此类患者的认识,更好地帮助临床医生对此类患者进行合理的诊治和管理,现就有关流行病学、检测注意事项及检测结果在静脉血栓栓塞症中的价值和相关治疗进行综述。  相似文献   
84.
Neural crest stem cells (NCSCs), a population of multipotent cells that migrate extensively and give rise to diverse derivatives, including peripheral and enteric neurons and glia, craniofacial cartilage and bone, melanocytes and smooth muscle, have great potential for regenerative medicine. Non-human primates provide optimal models for the development of stem cell therapies. Here, we describe the first derivation of NCSCs from cynomolgus monkey embryonic stem cells (CmESCs) at the neural rosette stage. CmESC-derived neurospheres replated on polyornithine/laminin-coated dishes migrated onto the substrate and showed characteristic expression of NCSC markers, including Sox10, AP2α, Slug, Nestin, p75, and HNK1. CmNCSCs were capable of propagating in an undifferentiated state in vitro as adherent or suspension cultures, and could be subsequently induced to differentiate towards peripheral nervous system lineages (peripheral sympathetic neurons, sensory neurons, and Schwann cells) and mesenchymal lineages (osteoblasts, adipocytes, chondrocytes, and smooth muscle cells). CmNCSCs transplanted into developing chick embryos or fetal brains of cynomolgus macaques survived, migrated, and differentiated into progeny consistent with a neural crest identity. Our studies demonstrate that CmNCSCs offer a new tool for investigating neural crest development and neural crest-associated human disease and suggest that this non-human primate model may facilitate tissue engineering and regenerative medicine efforts.  相似文献   
85.
肝癌是临床上常见的恶性肿瘤,因早期症状不典型,至发现时往往已为中晚期,失去最佳手术治疗时机和机会。作为非手术治疗之一的放射治疗技术,其发展在近年来已有了较大的进步。放疗包括体外放疗和体内放疗,皆具有一定的治疗效果和相对可控的不良反应。本文就肝癌放射治疗的应用进展作一综述。  相似文献   
86.
目的探索阿帕替尼治疗晚期及术后复发肺肉瘤样癌的疗效。方法收集2016年6月至2019年8月Ⅲ~Ⅳ期及术后复发的肺肉瘤样癌患者21例,口服阿帕替尼(250~425 mg/d)治疗,30 d为1个疗程,观察并分析疗效及评价安全性。结果21例患者中,完全缓解(CR)为0,部分缓解(PR)为14.3%(3例),稳定(SD)为33.3%(7例),疾病进展(PD)为52.4%(11例);客观反应率(ORR)为13.3%(3例),疾病控制率(DCR)为47.6%(10例)。中位总生存期(mOS)为4.6个月,中位无进展生存期(mPFS)为1.0个月。病灶≥6 cm(或≥5 cm)较<6 cm(或<5 cm)平均OS明显缩短,差异有统计学意义(P<0.05);术后分期Ⅰ~Ⅱ期较Ⅲ~Ⅳ期平均OS明显延长(P<0.05)。位于中央的病灶较周围的病灶平均OS明显缩短,差异有统计学意义(P<0.01)。性别、年龄(>60岁,≤60岁)、吸烟史(是/否)对疗效影响差异无统计学意义。常见不良反应包括高血压38.1%(8例)、蛋白尿23.8%(5例)、手足综合征28.6%(6例)、腹泻28.6(6例)、骨髓抑制38.1%(8例)。结论阿帕替尼治疗晚期及术后复发肺肉瘤样癌具有一定疗效,不良反应可控,病灶大小、位置及分期可能是疗效的独立影响因素。  相似文献   
87.
目的 探讨扶正消瘤颗粒对原发性肝癌血清中血管内皮生长因子(Vascular endothelial growth factor,VEGF)和缺氧诱导因子-1α(Hypoxia inducible factor-1α,HIF-1α)表达的影响及临床意义。方法 选择符合纳入标准的原发性肝癌患者66例,按1∶1随机分试验组和对照组。观察治疗过程中两组VEGF、HIF-1α水平的变化及对患者临床疗效指标的影响。结果 (1)在性别、年龄、合并乙型肝炎、Child-Pugh分级、AFP值、临床分期方面,试验组和对照组差异无统计学意义(P > 0.05)。(2)肝癌患者在治疗各时间节点的VEGF和HIF-1α表达水平呈线性正相关(r = 0.829,P < 0.001)。(3)VEGF浓度在经导管动脉化疗栓塞术(Transcatheter arterial chemoembolization,TACE)后3月降至术前水平(P > 0.05),HIF-1α在TACE后3月仍高于术前(P < 0.05)。(4)扶正消瘤颗粒可降低HIF-1α水平,下调VEGF的表达。(5)扶正消瘤颗粒可减少TACE序贯RFA治疗后的不良反应,提高患者的生活质量(P < 0.05)。(6)血清中VEGF水平与生活质量无明显相关性(P > 0.05,r = 0.251),HIF-1α水平与生活质量存在正相关性(P < 0.05,r = 0.450)。结论 扶正消瘤颗粒可明显改善TACE序贯RFA治疗后患者生活质量,降低HIF-1α水平,下调VEGF的表达,抑制肿瘤血管生成。  相似文献   
88.
ObjectivesTo assess consumption of dietary and herbal supplements (DHS) among patients in internal medicine departments and determine whether such use is documented in their medical files.Methods267 patients from three internal medicine departments of an academic medical center in Haifa, Israel were assessed prospectively with questionnaires about their DHS use in the month preceding hospitalization. DHS were categorized into vitamins & minerals, herbal supplements and others. Further data was then collected from patients' medical records on socio-demographic and medical characteristics, as well as documentation of DHS use.Results123 patients (50.6 %) used DHS on a daily basis. Most of them (53.7 %) were using more than one DHS. DHS use was more prevalent in older (OR = 1.02 [1.001–1.036], p = 0.034) and educated (OR = 0.482 [0.252-0.923], p = 0.028) patients. Vitamins & minerals were used mainly to enhance vitality and address laboratory abnormalities, whereas herbal supplements were used mainly for gastrointestinal problems (p < 0.001). DHS use was reported to the physicians by 42 % of the patients, mostly at the patients’ initiative [92 (82.1 %), p < 0.001)]. Vitamins and minerals were the most reported category of DHS (94 (57.3 %), p < 0.001). The use of DHS was reported to physicians for 112 DHS (41.8 %) but only 32 DHS (11.9 %) were documented in their medical files. The documentation of vitamins and minerals was significantly higher compared to herbal supplements documentation (29 (17.7 %) & 3 (2.9 %) respectively, P < 0.001).ConclusionsDHS are commonly used by patients hospitalized in the internal medicine departments. Many patients do not report such use to the physicians, and more strikingly, physicians do not document DHS use in patient medical files. This communication gap may have serious medico-legal ramifications due to DHS side effects and DHS interactions with other DHS and with conventional drugs.  相似文献   
89.
90.
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