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   40490篇
  免费   2506篇
  国内免费   788篇
耳鼻咽喉   357篇
儿科学   942篇
妇产科学   334篇
基础医学   3118篇
口腔科学   401篇
临床医学   5921篇
内科学   7750篇
皮肤病学   179篇
神经病学   2469篇
特种医学   1142篇
外国民族医学   2篇
外科学   4797篇
综合类   5788篇
预防医学   2370篇
眼科学   2478篇
药学   4356篇
  25篇
中国医学   1224篇
肿瘤学   131篇
  2023年   645篇
  2022年   798篇
  2021年   1387篇
  2020年   1552篇
  2019年   1297篇
  2018年   1288篇
  2017年   1261篇
  2016年   1235篇
  2015年   1176篇
  2014年   2616篇
  2013年   3019篇
  2012年   2107篇
  2011年   2409篇
  2010年   1805篇
  2009年   1790篇
  2008年   1911篇
  2007年   1910篇
  2006年   1705篇
  2005年   1421篇
  2004年   1241篇
  2003年   994篇
  2002年   890篇
  2001年   858篇
  2000年   668篇
  1999年   612篇
  1998年   530篇
  1997年   550篇
  1996年   458篇
  1995年   524篇
  1994年   470篇
  1993年   407篇
  1992年   422篇
  1991年   372篇
  1990年   348篇
  1989年   306篇
  1988年   317篇
  1987年   286篇
  1986年   261篇
  1985年   294篇
  1984年   298篇
  1983年   176篇
  1982年   240篇
  1981年   193篇
  1980年   171篇
  1979年   149篇
  1978年   131篇
  1977年   76篇
  1976年   64篇
  1975年   45篇
  1974年   31篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Tympanic membranes (TM) that have healed spontaneously after perforation present abnormalities in their structural and mechanical properties; i.e., they are thickened and abnormally dense. These changes result in a deterioration of middle ear (ME) sound transmission, which is clinically presented as a conductive hearing loss (CHL). To fully understand the ME sound transmission under TM pathological conditions, we created a gerbil model with a controlled 50% pars tensa perforation, which was left to heal spontaneously for up to 4 weeks (TM perforations had fully sealed after 2 weeks). After the recovery period, the ME sound transmission, both in the forward and reverse directions, was directly measured with two-tone stimulation. Measurements were performed at the input, the ossicular chain, and output of the ME system, i.e., at the TM, umbo, and scala vestibuli (SV) next to the stapes. We found that variations in ME transmission in forward and reverse directions were not symmetric. In the forward direction, the ME pressure gain decreased in a frequency-dependent manner, with smaller loss (within 10 dB) at low frequencies and more dramatic loss at high frequency regions. The loss pattern was mainly from the less efficient acoustical to mechanical coupling between the TM and umbo, with little changes along the ossicular chain. In the reverse direction, the variations in these ears are relatively smaller. Our results provide detailed functional observations that explain CHL seen in clinical patients with abnormal TM, e.g., caused by otitis media, that have healed spontaneously after perforation or post-tympanoplasty, especially at high frequencies. In addition, our data demonstrate that changes in distortion product otoacoustic emissions (DPOAEs) result from altered ME transmission in both the forward and reverse direction by a reduction of the effective stimulus levels and less efficient transfer of DPs from the ME into the ear canal. This confirms that DPOAEs can be used to assess both the health of the cochlea and the middle ear.  相似文献   
2.
3.
目的 降低神经外科术中获得性压力性损伤发生率。 方法 将2019年10~12月的1 378例神经外科择期手术患者作为对照组,采取常规护理措施预防术中获得性压力性损伤。将2020年10~12月的1 551例患者作为观察组,成立护理专案小组,开展多学科协作,实施护理专案改善。 结果 观察组术中获得性压力性损伤发生率为0.90%,对照组为2.18%,两组比较,差异有统计学意义(P<0.05);两组术中获得性压力性损伤治愈率比较,差异无统计学意义(P>0.05)。观察组预防术中获得性压力性损伤关键监测指标落实率较好,除术后规范交接班落实875例(61.40%)外,其他指标均>88.00%。 结论 多学科协作护理专案能够有效降低术中获得性压力性损伤发生率,提高术中获得性压力性损伤预防和管理质量。  相似文献   
4.
目的:比较高聚焦超声睫状体成形术(UCP)和睫状体冷冻术治疗难治性青光眼的疗效。方法:回顾性研究。收集2017-01/2020-12本院收治的难治性青光眼患者45例81眼,依据患者治疗方法不同分为睫状体冷冻术组22例40眼,高聚焦超声睫状体成形术组23例41眼。观察两组患者术前,术后1d,1wk,1、3mo眼压变化情况,采用疼痛数字等级评定量表(NRS)评估眼球疼痛程度,比较两组患者手术效果和并发症发生情况。结果:高聚焦超声睫状体成形术组手术总有效率明显高于睫状体冷冻术组(P<0.05),两组患者术后1d,1wk,1、3mo眼压和眼球疼痛程度均低于术前(均P<0.05),两组间患者术后各时间点眼压和眼球疼痛程度比较均有差异(均P<0.05)。高聚焦超声睫状体成形术组患者结膜充血、角膜水肿、前房炎性渗出、反应性高眼压和前房积血并发症发生率低于睫状体冷冻术组(P<0.05)。结论:高聚焦超声睫状体成形术治疗难治性青光眼疗效明确,在降低患者眼压、减少眼球疼痛和并发症发生方面较睫状体冷冻术有明显优势。  相似文献   
5.
目的:应用扫频光学相干断层扫描血管成像(SS-OCTA)对比研究白内障术中不同眼内压患者手术前后黄斑区血流的变化情况,为白内障个性化手术参数设计提供临床参考。

方法:前瞻性随机对照研究。收集2021-01/04于四川省人民医院住院行白内障手术的患者61例77眼,使用随机数字表分为A组(37眼)和B组(40眼),术中分别予以75、90cm灌注瓶瓶高,相当于55.5、66.6mmHg术中平均眼内压。所有患者除常规眼科检查外,术前、术后1、7、30d均行黄斑区SS-OCTA检查,观察黄斑区视网膜厚度及放射状毛细血管网(RPCP)层、浅层血管网(SVP)层、中层血管网(IVP)层、深层血管网(DVP)层灌注面积和血管密度。

结果:手术前后各时间点两组患者最佳矫正视力(BCVA)、眼压、黄斑中心凹无血管区(FAZ)面积、黄斑区视网膜厚度及各层灌注面积和血管密度均无组间差异性(均P>0.05),但均有时间差异性(均P<0.05),两组患者术后各时间点BCVA均较术前明显改善,眼压和FAZ面积均较术前下降(均P<0.05),黄斑区视网膜厚度及各层灌注面积和血流密度均较术前增加。

结论:白内障术后黄斑区视网膜厚度及各层血流密度和灌注面积均增加,FAZ面积下降,有助于促进术后视力的恢复,且术中选择55.5、66.6mmHg不同眼内压情况下,患者术后眼底血流改变情况无明显差异,故术中可以灵活选择眼内压,为患者提供个性化手术设计方案。  相似文献   

6.
《Pancreatology》2022,22(1):74-82
ObjectivePost-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP) is the most common complication following ERCP and the mechanism is not fully understood. This study evaluated the changes in the inflammatory response, cellular apoptosis, and tight junction integrity in a rat model of pancreatitis to explore the underlying mechanism.MethodsPEP was induced in rats by retrograde biliopancreatic ductal infusion of contrast agents or saline. Pancreatic tissues were harvested and evaluated by histopathologic, immunohistochemical, immunofluorescence, and Western blot analyses. In addition, amylase and proinflammatory cytokines in plasma were quantified by ELISA assay.ResultsPEP rats developed more severe acute pancreatitis than the sham group after injection of the contrast agent or isotonic saline. PEP rats exhibited increased tissue damage, plasma amylase, proinflammatory cytokines, necrosis, inflammatory infiltrates, apoptosis, and tight junction disruption. At the molecular level, contrast agent and isotonic saline-injected PEP rats demonstrated elevated NF-κB p65 and STAT3 pathways activation, altered expression and activation of apoptosis-related proteins, and suppressed expression of tight junction molecules. However, the contrast agent concentration had no effect on these changes.ConclusionsIn models of acute pancreatitis induced using contrast agent and hydrostatic pressure, the contrast agent and high hydrostatic pressure easily induced the inflammatory response, apoptosis, and tight junction disruption. It is noteworthy that no significant difference in damaged pancreatic acinar cells was observed with different concentrations of the contrast agent.  相似文献   
7.
AIM: To investigate fluctuation of intraocular pressure (IOP) and seasonal variation of 24-hour IOP during one year in healthy participants METHODS: Totally 13 young healthy volunteers participated in this study. IOP was measured with Canon TX-20 at about 8:00-9:00 a.m. from Monday to Friday every week for a whole year. They also underwent 24-hour IOP examination every three months. Blood pressure, heart rate, temperature, humidity, atmosphere pressure, sunshine duration and other environment parameters were recorded. RESULTS: The yearly fluctuation curve showed IOP in the summer months were lower than other seasons. In the multivariable generalized estimating equation analysis, IOP had a negative correlation with both temperature and sunshine duration (P<0.05). There also was a seasonal effect on 24-hour IOP. However, all intraclass correlation coefficients values of minimum, maximum and average of the 24-hour IOP and each individual IOP were less than 0.30. CONCLUSION: IOP is trend to be higher in cold days than warm days. IOP have negative association with both environmental temperature and duration of sunshine. On a season-to-season basis, 24-hour IOP is not highly reproducible in healthy volunteers.  相似文献   
8.
9.
10.
席悦  张京铮 《中国校医》2022,36(12):939
目的 探讨经鼻间歇正压通气与大剂量牛肺表面活性剂治疗重症新生儿呼吸窘迫综合征的应用效果。方法 选取2019年3月—2020年6月在本院就诊的新生儿呼吸窘迫综合征患儿102例,按随机数字表法分为两组,各51例。2组患儿均接受经鼻间歇正压通气辅助呼吸及注射用牛肺表面活性剂治疗,对照组采用标准剂量治疗,观察组采用大剂量治疗。对比2组临床疗效、临床相关指标、血气分析指标,并记录两组不良反应发生情况。结果 观察组治疗总有效率为96.08%,高于对照组的84.31%,(χ2=3.991,P<0.05)。观察组用药次数、住院时间、氧疗时间及机械通气时间为(1.21±0.26)次、(14.42±2.14)d、(79.25±7.36)h、(65.24±5.01)h,短于对照组的(1.58±0.45)次、(18.74±3.87)d、(88.24±7.85)h、(74.17±6.21)h(t=5.084、6.976、5.966、7.993,P均<0.05);观察组治疗3 d后血氧分压(partial pressure of oxygen,PaO2)、氧合指数分别为(88.45±6.21)mm Hg、(350.21±12.25)mm Hg,高于对照组的(81.36±5.14)mm Hg、(336.14±11.41)mm Hg,二氧化碳分压(Partial Pressure of Carbon Dioxide,PaCO2)为(43.14±3.65)mm Hg,低于对照组的(50.21±4.35)mm Hg,(t=6.281、6.002、8.892,F=39.446、79.042、36.026,P值均<0.05)。2组均无严重不良反应发生。结论 经鼻间歇正压通气与大剂量牛肺表面活性剂治疗重症新生儿呼吸窘迫综合征患儿利于改善患儿氧合指数,进而减少机械排气时间及住院时间,值得应用。  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