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   244627篇
  免费   23054篇
  国内免费   17004篇
耳鼻咽喉   2403篇
儿科学   3068篇
妇产科学   2348篇
基础医学   24761篇
口腔科学   4396篇
临床医学   31122篇
内科学   32301篇
皮肤病学   2690篇
神经病学   10871篇
特种医学   9155篇
外国民族医学   124篇
外科学   24689篇
综合类   49529篇
现状与发展   75篇
一般理论   13篇
预防医学   18881篇
眼科学   5949篇
药学   25809篇
  255篇
中国医学   17045篇
肿瘤学   19201篇
  2024年   908篇
  2023年   3736篇
  2022年   9326篇
  2021年   11821篇
  2020年   9282篇
  2019年   7383篇
  2018年   7881篇
  2017年   7778篇
  2016年   7221篇
  2015年   11445篇
  2014年   13863篇
  2013年   13637篇
  2012年   19909篇
  2011年   21757篇
  2010年   15512篇
  2009年   12646篇
  2008年   14634篇
  2007年   14514篇
  2006年   13789篇
  2005年   12460篇
  2004年   8457篇
  2003年   7885篇
  2002年   6642篇
  2001年   5271篇
  2000年   4717篇
  1999年   4430篇
  1998年   2769篇
  1997年   2626篇
  1996年   2047篇
  1995年   1812篇
  1994年   1461篇
  1993年   956篇
  1992年   1100篇
  1991年   924篇
  1990年   836篇
  1989年   692篇
  1988年   584篇
  1987年   528篇
  1986年   386篇
  1985年   296篇
  1984年   149篇
  1983年   120篇
  1982年   74篇
  1981年   83篇
  1980年   49篇
  1979年   72篇
  1977年   19篇
  1976年   17篇
  1974年   22篇
  1973年   28篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
输尿管上段结石的微创手术治疗   总被引:12,自引:0,他引:12  
目的:探讨输尿管上段结石的治疗方法。方法:回顾性分析输尿管镜下气压弹道碎石(URSL),后腹腔镜输尿管切开取石(RLU)、经皮肾穿刺取石(PCNL)治疗输尿管上段结石患者的临床资料。其中URSL组25例,RLU组20例。PCNL组9例。结果:URSL组碎石成功18例;7例不成功,其中3例改为开放手术,1例改为后腹腔镜取石。2例行ESWL术,1例仅留置双J管。术后1个月拔管后自行排出。2例并发输尿管穿孔。RLU组取石成功18例,2例滑入肾内,经配合输尿管镜和腹腔镜直视下经皮肾穿刺取石成功,术后15例有伤口漏尿。PCNL组成功9例,无并发症。结论:USRL创伤小。术后恢复快。是治疗输尿管上段结石的较为满意的治疗方法。PCNL创伤小,取石成功率高,在结石靠近肾盂、儿童输尿管上段结石并同侧肾结石和结石以下输尿管狭窄时应优先考虑。但技术难度较大。RLU可作为URSL不成功后的辅助治疗方法。  相似文献   
82.
目的:研究比较纸夹板内收位固定与石膏外展位固定治疗Bennett骨折的疗效差异。方法:选择2005年10月至2007年4月门诊就诊的70例Bennett骨折患者,按区组随机的方法分为试验组35例(纸夹板内收位固定)和对照组35例(石膏外展位固定)进行治疗。骨折达到临床愈合拆除固定后,对患者进行为期6个月的随访观察。分别于骨折后6、8、12、16、20及24周按改良的Gabriele评分系统对其患手功能进行量化评分比较。结果:两组的优良率在8、12、16及20周时比较试验组优于对照组,差异有统计学意义(P〈0.05);6周和24周时比较差异无统计学意义(P〉0.05)。两组在功能评分方面,8、12、16、20及24周时比较试验组高于对照组,差异有统计学意义(P〈0.05);6周时积分差异无统计学意义(P〉0.05)。结论:在Bennett骨折的治疗中,纸夹板内收位固定与石膏外展位固定相比能明显加快患手功能的恢复,而且固定轻便、舒适,患者易于接受,可以作为一种有效的固定方法在临床推广。  相似文献   
83.
A conjugate of antisense oligodeoxynucleotide (AS ODN) covalently linked with deoxorubicin (DOX) was synthesized. Its properties and antitumour activity in human carcinoma DOX resistant cells (KB-A-1) were investigated in vitro. The results showed that the conjugate was strongly stable both in Dulbecco's Phosphate-Buffered Saline (PBS) and in culture medium. The intracellular concentration of the conjugate was higher than that of the AS DON by HPLC analysis. The conjugate showed potent dose-dependent inhibition to the growth of KB-A-1 cells. Chemosensitivity of KB-A-1 cells to DOX was also investigated in vitro. When the cells were first exposed to the conjugate (0.5 microM) and then exposed to DOX for 24 h, the IC50 value of DOX decreased from 21.5 to 2.2 microM. In contrast, when treated with the mixture of the same concentration of the AS ODN with equivalent DOX, the IC50 value of DOX was 16.8 microM. Intracellular DOX concentration was detected in KB-A-1 treatment with the conjugate in vitro by HPLC. The results showed that the intracellular DOX concentration was 6.4-fold increased in KB-A-1 cells treated with the conjugate compared to treatment with DOX alone. In contrast, 1.8-fold increasing was observed when treated with the AS ODN. Western blot analysis showed a significantly decrease in the amount of P-glycoprotein in KB-A-1 cells. These results suggest that the conjugate is effective in reversing multidrug resistance. Certainly, further studies are conducting to explore the antitumour effect of the conjugate in vivo.  相似文献   
84.
目的 对单纯行裂隙关闭术和同期行咽后壁咽成形术的大龄腭裂患者,术前、术后发音效果进行检测分析和对比研究,评定手术的治疗效果.方法 对24例同期行腭裂关闭术及咽后壁组织瓣咽成形术治疗和12例单纯行裂隙关闭术的大龄腭裂患者,术前、术后用鼻咽纤维镜检测其腭咽闭合情况,应用通用音频谱分析系统,对本组术后患者腭裂语音进行声学分析.结果 所有腭裂修复术后,创口均达到临床Ⅰ期愈合,语音也有不同程度改善.大龄腭裂患者采用腭裂关闭及同期咽成形术的修复组,术后发音明显优于单纯行裂隙关闭组.结论 大龄腭裂患者,采用腭裂关闭及同期咽成形术,是提高腭咽闭合和改善发音较好的手术方法.  相似文献   
85.
目的研究肾草酸钙结石形成对肾组织bikunin基因和间α胰蛋白酶抑制物(IαI)蛋白表达的影响,探讨bikunin在尿结石形成中的意义。方法诱导实验性大鼠肾草酸钙结石模型,收集结石大鼠、正常大鼠、临床肾结石和非结石患者每组各8例的肾组织标本。采用免疫组化、逆转录聚合酶链反应(RT-PCR)和计算机图像分析技术分别检测所有大鼠和人肾组织中bikuninmRNA和IαI蛋白的表达水平。结果正常大鼠和非结石患者肾组织均存在bikuninmRNA和IαI蛋白的表达。肾草酸钙结石形成后,结石大鼠肾组织IαI蛋白的灰度值和bikuninmRNA的相对表达水平分别为198.43±15.17、0.70±0.14;肾结石患者肾组织IαI蛋白的灰度值和bikuninmRNA的相对表达水平分别为263.25±17.41、1.27±0.13,分别和对照组相比,均显著增加(P<0.05)。结论Bikunin作为构成IαI的轻链结构,在肾草酸钙结石形成后,bikuninmRNA的表达迅速增强,提示机体通过肾脏合成更多的bikunin来抑制肾草酸钙结石的形成。  相似文献   
86.
改良开放性手术治疗巨大良性前列腺增生症   总被引:2,自引:0,他引:2  
目的探讨巨大良性前列腺增生症的开放性手术治疗方法及效果。方法回顾分析16例巨大良性前列腺增生症,年龄61~88岁,平均74岁。作耻骨上经膀胱前列腺切除术。结果手术均成功;手术时间35~65min,出血量100~200mL,术后前列腺重量为200~520g,平均215g;膀胱冲洗2~3d,拔导尿管5~7d;术后3d再出血1例,经DSA同侧髂内血管栓塞止血成功,排尿困难1例,短期尿失禁1例,其余患者术后均排尿通畅,控尿良好。结论开放性手术治疗巨大良性前列腺增生症,其梗阻解除彻底,是一种合理的治疗方法。恰当的手术方法是提高疗效及降低并发症的关键。  相似文献   
87.
N(G)-nitro-arginine (NNA) is known to exhibit stereoselective pharmacokinetics in which N(G)-nitro-d-arginine (d-NNA) has a faster clearance rate than N(G)-nitro-l-arginine (l-NNA) in anesthetized rats, and d-NNA undergoes unidirectional chiral inversion. It was postulated that chiral inversion of d-NNA was performed in a two-step pathway by d-amino acid oxidase (DAAO) followed by an unidentified transaminase. Such chiral inversion contributes (at least partially) to the pharmacokinetic stereoselectivity of NNA. This study used the selective inhibitor of DAAO, sodium benzoate, to test the above hypothesis. An i.v. bolus injection of d-NNA (32 mg/kg) and l-NNA (16 mg/kg) in conscious rats exhibited biphasic disposition with different pharmacokinetic parameters in a stereospecific manner (approximately 5-10-fold differences). Unidirectional chiral inversion of d-NNA but not l-NNA was found from these animals. In addition to its similar inhibitory effects on the d-NNA conversion and DAAO activity in kidney homogenates, sodium benzoate completely blocked chiral inversion of d-NNA and led to a smaller stereospecific difference, reflected by a nearly 50% reduction of d-NNA clearance and a 2-fold increase in t(1/2) and area under the curve of d-NNA in benzoate-pretreated rats. The results suggest that DAAO plays an essential role in chiral inversion of d-NNA and chiral inversion contributes mostly to the pharmacokinetic stereospecificity of NNA.  相似文献   
88.
Conclusions  Despite the utility and benefits that each imaging modality has to offer, it is easy to see why there is still no perfect choice for a noninvasive cardiac imaging modality to assist in the management of chest pain patients. All of the current imaging techniques have their own significant strengths and weaknesses when compared with other modalities. SPECT and echocardiography are wellestablished technologies that can directly assess the presence of myocardial ischemia and its functional consequence on RF; newer and more expensive techniques such as MDCT and CMR can directly assess coronary anatomy and have just started to be evaluated in the acute chest pain setting. There are no studies that directly compare these technologies, and more data are clearly needed before the question of whether anatomic imaging versus perfusion/function imaging is the better approach can be answered. Other comparisons such as relative safety, availability, logistics, and cost-effectiveness between the various technologies are also lacking. Of all of the imaging modalities discussed, MCE is the only portable technology. The images do not require expensive software or other technology for offline processing before interpretation, and any trained cardiologist can read the study at the bedside or, potentially, over the Internet, providing near-instantaneous results in the acute cardiac setting, where time is of the essence. MCE is also relatively cheap compared with other technologies, a potential advantage for payors but not necessarily for payees. How reimbursement rates and fee structures eventually affect clinical practice is also unknown. Despite these and other questions that need to be answered before any one technique will be used exclusively, the future of noninvasive cardiac imaging remains an exciting and ever-changing field. The adaptation of any one of these techniques into its proper role in the ED Journal of Nuclear Cardiology Wyrick and Wei 753 Volume 13, Number 6;749-55 Cardiac imaging in patients with chest pain will take considerably more time and effort in terms of research, money, and time-tested clinical experience.  相似文献   
89.
泰素蒂加顺铂治疗进展期NSCLC的临床研究   总被引:5,自引:0,他引:5  
目的观察泰素蒂加顺铂方案治疗进展期非小细胞肺癌的临床疗效、毒副作用。方法收集可评价疗效的进展期非小细胞肺癌50例,以泰素蒂加顺铂方案进行化疗,泰素蒂75 mg/m2静脉滴注,第1天;顺铂25 mg/m2~30 mg/m2静脉滴注,第2天~第5天,每3周为一个周期,2~3周期后评价疗效和毒副反应并随访。结果50例患者中,总有效率为50.0 %,其中初治病例为53.1 %,复治病例为44.4 %,初复治病例间差异无显著性(P >0.05)。中位缓解期为5个月。中位生存期为9.5个月,1年生存率为61.0 %。毒副反应主要为骨髓抑制,白细胞下降达Ⅲ度、Ⅳ度者52.0 %,血小板下降达Ⅲ度、Ⅳ度者为14.0 %。血红蛋白下降不严重。其他毒副反应还有脱发、过敏反应、水钠潴留、静脉炎、末梢神经炎、口腔炎、腹泻等,但发生率均较低。结论泰素蒂加顺铂方案治疗进展期非小细胞肺癌,特别是复发病例,临床疗效比较满意,毒副反应能够耐受。辅以G蛳CSF可防治重度的骨髓抑制,有较好的临床应用价值。  相似文献   
90.
骨髓基质干细胞修复兔关节软骨缺损的实验研究   总被引:1,自引:1,他引:0  
目的研究以多聚乙醇酸(PGA)为支架的骨髓基质干细胞(BMSCs)复合物修复兔膝关节软骨缺损的情况。方法体外培养扩增的自体BMSCs种植于PGA支架并培养72h,然后将支架-细胞复合物植入兔关节软骨缺损模型。术后12周处死动物,标本行大体观察、组织学检查及Ⅱ型胶原免疫组化染色。结果BMSCs-PGA复合物植入后形成丰富的透明软骨样修复组织,新生软骨无明显退变。对照组主要为纤维组织及软骨下骨修复。结论BMSCs-PGA复合物可修复关节软骨缺损。  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