全文获取类型
收费全文 | 54493篇 |
免费 | 5421篇 |
国内免费 | 2303篇 |
专业分类
耳鼻咽喉 | 553篇 |
儿科学 | 1157篇 |
妇产科学 | 489篇 |
基础医学 | 4929篇 |
口腔科学 | 448篇 |
临床医学 | 6598篇 |
内科学 | 8795篇 |
皮肤病学 | 447篇 |
神经病学 | 10146篇 |
特种医学 | 1720篇 |
外国民族医学 | 11篇 |
外科学 | 4300篇 |
综合类 | 8995篇 |
现状与发展 | 8篇 |
预防医学 | 2482篇 |
眼科学 | 2092篇 |
药学 | 4726篇 |
35篇 | |
中国医学 | 2639篇 |
肿瘤学 | 1647篇 |
出版年
2024年 | 253篇 |
2023年 | 1165篇 |
2022年 | 1846篇 |
2021年 | 2615篇 |
2020年 | 2476篇 |
2019年 | 2424篇 |
2018年 | 2372篇 |
2017年 | 2321篇 |
2016年 | 2331篇 |
2015年 | 2237篇 |
2014年 | 3806篇 |
2013年 | 4459篇 |
2012年 | 3138篇 |
2011年 | 3219篇 |
2010年 | 2738篇 |
2009年 | 2617篇 |
2008年 | 2681篇 |
2007年 | 2622篇 |
2006年 | 2461篇 |
2005年 | 2116篇 |
2004年 | 1752篇 |
2003年 | 1591篇 |
2002年 | 1373篇 |
2001年 | 1070篇 |
2000年 | 955篇 |
1999年 | 720篇 |
1998年 | 627篇 |
1997年 | 550篇 |
1996年 | 494篇 |
1995年 | 428篇 |
1994年 | 331篇 |
1993年 | 278篇 |
1992年 | 265篇 |
1991年 | 249篇 |
1990年 | 187篇 |
1989年 | 175篇 |
1988年 | 166篇 |
1987年 | 160篇 |
1986年 | 140篇 |
1985年 | 152篇 |
1984年 | 128篇 |
1983年 | 71篇 |
1982年 | 103篇 |
1981年 | 98篇 |
1980年 | 57篇 |
1979年 | 55篇 |
1978年 | 47篇 |
1977年 | 29篇 |
1976年 | 21篇 |
1975年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
目的:探讨外周血循环内皮细胞(CEC)和糖尿病肾病(DN)的相关性,以及银杏达莫注射液在DN防治中的可能作用。方法:检测65例2型糖尿病患者24h尿白蛋白排泄率(UAER)及CEC数,分析两者的相关性。将UAER为30~300mg·d-1的45例患者随机分为两组,常规治疗组22例,进行常规降血糖、控制血压等治疗;银杏达莫治疗组23例,在常规治疗基础上静脉滴注银杏达莫注射液2周。比较两组治疗前后血糖、血压、UAER及CEC水平的变化。结果:单纯糖尿病(SDM)组和早期糖尿病肾病(EDN)组的外周血CEC水平比对照组(NC)显著性升高,并呈逐渐增高的趋势(P<0.01)。UAER与收缩压(SBP)、外周血CEC水平呈正相关(P<0.01)。EDN组中,银杏达莫治疗后UAER及CEC明显降低(P<0.01);而常规治疗组无明显变化。线性多元逐步回归分析表明,银杏达莫治疗后UAER的改变与CEC数的变化成正相关(P<0.01)。结论:血管内皮细胞(VEC)损伤在DN发生发展中起重要作用,银杏达莫对VEC的保护作用可能是其延缓DN发展的重要机制。 相似文献
102.
103.
Background: Retinal pigment epithelium (RPE)lesions are predictive congenital phenotypic markersfor familial adenomatous polyposis (FAP). Thisprospective screening study aims at assessing theincidence and significance of these lesions in FAPpatients and their family members.Methods: Sixty-two members from three familiesincluding five patients with the diagnosis of FAP havebeen ophthalmologically surveyed. All RPE lesions weredocumented with fundus photography and fluoresceinangiography was performed in 13 subjects.Sigmoidoscopy and/or radiological examination wereperformed annually in 9 family members with typicalRPE lesions during 4 years to allow early diagnosis ofFAP.Results: Typical RPE lesions were present infive FAP patients and 15 family members.Telangiectatic dilatations in the retinal peripherywith small dot-like hemorrhages were detected in 6subjects from 3 families These lesions wereparticularly evident on fluorescein angiography.Annual colon analysis showed polyps in 3 out of 9subjects who were positive for RPE lesions.Conclusion: RPE lesions are valuable as aclinical marker in predicting FAP. The co-existingperipheral vascular alterations which have not beenreported before, are probably related to FAP. 相似文献
104.
HATIM A. OMAR M.D. LARRY A. RHODES M.D. ROLANDO RAMIREZ JELICA ARSICH M.D. STANLEY EINZIG M.D. Ph .D. 《Journal of cardiovascular electrophysiology》1996,7(12):1197-1203
Antiarrhythmic and Placental Vessels. Introduction : Antiarrhythmic medications are commonly used during pregnancy for treatment of maternal or fetal arrhythmias, but little is known about their effect on human placental vascular tone and, consequently, placental blood flow. The objective of this study was to evaluate the tone responses caused by antiarrhythmic medications in human placental vessels from normal term pregnancies in vitro.
Methods and Results : Isolated human placental arteries and veins from uncomplicated term pregnancies incubated in Krebs'-bicarbonate under 5% oxygen/5% carbon dioxide/balance nitrogen (PO2 35 to 38 torr) were exposed to cumulative doses of quinidine, procainamide, lidocaine, flecainide, propranolol, amiodarone, verapamil, digoxin, and adenosine after submaximal contraction with 5-hydroxytryptamine. The study was conducted both in the presence and absence of endothelium. The addition of the tested medications caused a significant, dose-dependent relaxation of human placental arteries and veins except for adenosine, which induced a sustained, dose-dependent contraction of human placental vessels regardless of the presence or absence of tone. Removal of the endothelium did not alter these responses.
Conclusions : Based on these results, the medications tested should have no decremental effect on placental blood flow, with the possible exception of adenosine, which causes significant. dosedependent contraction of human placental vessels in vitro. Should similar contraction be present in vivo, it may have an adverse effect on the fetus when administering adenosine to pregnant women at term or during labor. 相似文献
Methods and Results : Isolated human placental arteries and veins from uncomplicated term pregnancies incubated in Krebs'-bicarbonate under 5% oxygen/5% carbon dioxide/balance nitrogen (PO
Conclusions : Based on these results, the medications tested should have no decremental effect on placental blood flow, with the possible exception of adenosine, which causes significant. dosedependent contraction of human placental vessels in vitro. Should similar contraction be present in vivo, it may have an adverse effect on the fetus when administering adenosine to pregnant women at term or during labor. 相似文献
105.
The goal of the present study is to develop a technique for laparoscopic aortobifemoral bypass.Piglets weighing between 60 and 78 kg were anesthetized with halothane. The lateral retroperitoneal approach was preferred to the more familiar anterior transperitoneal approach and was successfully completed in 19 piglets. The piglets were placed in the right lateral decubitus position. The first port (2 cm) was inserted halfway between the tip of the 12th rib and the iliac crest. Four other trocars were placed in the retroperitoneum after balloon inflation had allowed creation of a space which permitted visualization of the aorta from the left renal artery down to the aorto-iliac junction. After evacuation of the retropneumoperitoneum, the cavity was maintained using an abdominal lift device and a retractor.Using this approach, we performed four aortobifemoral bypasses (end-to-end aortic anastomosis) after conventional intravenous heparinization (100 IU/kg) in less than 4 h. Blood loss did not exceed 250 ml and the hematocrit remained stable. Postmortem evaluation of the grafts revealed they were positioned as in a conventional bypass, their limbs having followed in the created retroperitoneal tunnels along the path of the native arteries. No mortality occurred before sacrifice of the animals. We believe that this first performed series of totally retroperitoneal laparoscopic aortobifemoral bypasses in the porcine model is useful in preparation for human application due to the anatomical similarities in the periaortic region. 相似文献
106.
目的:观察偏瘫患者早期床上训练的效果。方法:对58例脑血管意外致偏瘫患者随机分成2组:观察组30例,护理中指导早期床上体操训练;对照组28例,按常规护理。以上、下肢肌力和日常生活活动能力(ADL)为评价指标,于训练开始时、训练4周、训练8周各评价1次。结果:观察组训练4周、8周时患侧上肢肌力以及ADL水平明显增加,与对照组比较有显著差异(P<001)。患侧下肢肌力训练4周及8周时均增加,与对照组比较,4周时无明显差异(P>005),8周时有显著性差异(P<001)。结论:对早期偏瘫患者实施床上功能训练,不仅可以提高患者的生命质量,而且可以减少、甚至解除患者及家属的经济和精神负担。 相似文献
107.
S. Sunano T. Shimada K. Moriyama K. Shimamura 《Clinical and experimental pharmacology & physiology》1990,17(6):413-425
1. The time courses of the relaxation, induced by removal of extracellular Ca2+, of K-depolarized mesenteric artery preparations from stroke prone spontaneously hypertensive rats (SHRSP) and Wistar-Kyoto rats (WKY) were compared. 2. The time course of the decline in extracellular Ca2+ was estimated from the time course of the relaxation and the concentration-response curve of K(+)-depolarized preparations to Ca2+. The time course of the decline in the intracellular free Ca2+ concentration was also estimated from the reported relation between Ca2+ concentration and the contraction of skinned vascular smooth muscle. 3. The time course of relaxation was exponential, the curve being made up of three components. The time course was slower in preparations from SHRSP, especially the first component of the relaxation curve. 4. The time courses of the decline in the intracellular and extracellular Ca2+ concentrations were also exponential, being made up of three components and were also slower in the preparation made from SHRSP. 5. The wall and muscle layer of the mesenteric arteries used in the present experiments were significantly thicker in the SHRSP preparations. 6. Calculation of the half relaxation time, based on the diffusion of Ca2+ across the blood vessel wall, suggested that the slower relaxation in preparations from SHRSP is due largely to the thicker muscle layer, although differences in Ca2+ sequestration by the smooth muscle cells may also be involved. 相似文献
108.
复合带瓣人工血管替换升主动脉和主动脉瓣(24例报告) 总被引:1,自引:0,他引:1
报告24例升主动脉瘤伴主动脉瓣关闭不全行升主动脉和主动脉瓣替换及冠状动脉开口移植术(Bental术22例,底盘法2例)。13例伴有升主动脉夹层分离,对其中8例DeBakeyI型者,以Teflon毡条内外加固主动脉切端后吻合。13例用人工血管周围间隙与右心耳吻合以控制升主动脉吻合之外的出血。3例以人工血管片环包主动脉吻合口控制局部广泛渗血及出血。2例术毕不能脱离体外循环死亡,手术死亡率83%。随访平均218个月,2例死于蛛网膜下腔出血,1例右股动脉栓塞经手术治愈;其余病人康复良好,心功能(NYHA)I~II级。 相似文献
109.
小血管套叠粘接吻合法在血液透析者中建立动静脉内瘘的应用 总被引:3,自引:1,他引:2
慢性肾病患者常需要建立动静脉内瘘进行透析,常规间断缝合法吻合动静脉难度大、耗时长。为了缩短吻合时间,提高远期通畅率,进行了套叠粘接吻合法建立动静脉内瘘的实验研究,并将这一方法应用于透析患者建立动静脉内瘘的血管吻合。将动脉端套入静脉端,只需吻合两针,用医用胶封闭吻合口。经8个月观察,通畅率达100%,血流量均超过300ml/min。达到了透析需要。 相似文献
110.
Shang-Jin Shi Hiromi Rakugi Koichi Higashimori Jitsuo Higaki Hiroshi Mikami Toshio Ogihara 《Clinical and experimental pharmacology & physiology》1994,21(10):767-773
1. We previously reported that angiotensin II release from the mesenteric arteries of Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR) increased in a time-dependent manner as a result of the isolation of the arteries and perfusion. This phenomenon appeared to be due to the withdrawal of circulating angiotensin II (AII). 2. The purpose of the present study was to test the hypothesis that vascular AII generation may be negatively regulated by circulating AII in WKY and SHR, and to clarify the role of this vascular angiotensin II in the sustained hypertension of SHR following nephrectomy. 3. The mesenteric arteries from kidney-intact and nephrectomized WKY and SHR were perfused and the amount of AII released into the perfusate was measured. The effects of the angiotensin converting enzyme inhibitor, captopril, and the effects of supplementation of renal renin and circulating angiotensins to nephrectomized rats, by blood exchange between kidney-intact and nephrectomized rats, on AII release were examined to clarify the pathway of vascular AII generation after nephrectomy. 4. Nephrectomy caused augmentation of vascular AII release both in WKY and SHR in spite of the abolishment of circulating renin. Captopril reduced this enhanced release of AII, but blood exchange did not affect it. There was no significant difference in these responses between WKY and SHR. 5. These results suggest that WKY and SHR have in common a potent pathway for production of vascular AII in response to the withdrawal of circulating AII, although this pathway is not responsible for the sustained hypertension of SHR after nephrectomy. The precise pathophysiological role of this pathway remains to be elucidated. 相似文献