全文获取类型
收费全文 | 4436篇 |
免费 | 201篇 |
国内免费 | 108篇 |
专业分类
耳鼻咽喉 | 9篇 |
儿科学 | 144篇 |
妇产科学 | 93篇 |
基础医学 | 540篇 |
口腔科学 | 16篇 |
临床医学 | 662篇 |
内科学 | 779篇 |
皮肤病学 | 4篇 |
神经病学 | 188篇 |
特种医学 | 673篇 |
外科学 | 558篇 |
综合类 | 503篇 |
预防医学 | 73篇 |
眼科学 | 24篇 |
药学 | 362篇 |
1篇 | |
中国医学 | 65篇 |
肿瘤学 | 51篇 |
出版年
2023年 | 38篇 |
2022年 | 60篇 |
2021年 | 102篇 |
2020年 | 107篇 |
2019年 | 92篇 |
2018年 | 99篇 |
2017年 | 89篇 |
2016年 | 71篇 |
2015年 | 88篇 |
2014年 | 201篇 |
2013年 | 217篇 |
2012年 | 172篇 |
2011年 | 230篇 |
2010年 | 216篇 |
2009年 | 217篇 |
2008年 | 226篇 |
2007年 | 253篇 |
2006年 | 214篇 |
2005年 | 203篇 |
2004年 | 162篇 |
2003年 | 152篇 |
2002年 | 130篇 |
2001年 | 115篇 |
2000年 | 112篇 |
1999年 | 99篇 |
1998年 | 109篇 |
1997年 | 88篇 |
1996年 | 91篇 |
1995年 | 88篇 |
1994年 | 65篇 |
1993年 | 65篇 |
1992年 | 62篇 |
1991年 | 48篇 |
1990年 | 50篇 |
1989年 | 31篇 |
1988年 | 40篇 |
1987年 | 32篇 |
1986年 | 35篇 |
1985年 | 43篇 |
1984年 | 46篇 |
1983年 | 26篇 |
1982年 | 34篇 |
1981年 | 27篇 |
1980年 | 20篇 |
1979年 | 16篇 |
1978年 | 14篇 |
1977年 | 12篇 |
1976年 | 9篇 |
1975年 | 7篇 |
1973年 | 6篇 |
排序方式: 共有4745条查询结果,搜索用时 593 毫秒
31.
年轻人冠状动脉壁平滑肌细胞的表型变化及其与巨噬细胞的关系——免疫组织化学研究 总被引:1,自引:0,他引:1
选用年轻人冠状动脉材料,免疫组织化学方法,观察了弥漫性内膜增厚、脂纹、动脉粥样硬化斑块中平滑肌细胞的免疫表型变化,并将这些变化同巨噬细胞进行了联系。结果表明,凡是有巨噬细胞浸润之处,不管何种病变,该处的平滑肌细胞便失去了相应抗体的反应性,但仍能被抗间叶细胞抗体所标记,提示平滑肌细胞已经发生表型转变。这一现象说明巨噬细胞在平滑肌细胞表型转变过程中起重要作用,有助于人们对动脉粥样硬化病变、冠脉成形术后再狭窄病变发生过程的认识。 相似文献
32.
R. C. Read 《Hernia》2005,9(1):79-83
Preperitoneal, a word coined by Nyhus in the 1960s, has been applied not only to posterior approaches that he, Stoppa, and Wantz popularized but to anterior exposures of the groin, which divide the transversalis fascia. This assumes that all give similar views of the easily cleaved space of Bogros. However, accumulated anatomical observations reveal the transversalis fascia as having not one but two layers. The inferior epigastric vessels run between rather than in the preperitoneal space, which is avascular and has its own fascia lining the peritoneum. Historical evidence shows that both the midline Cheatle-Henry and lateral Ugahary-Kugel approaches, which transect the abdominal wall, provide excellent exposure of the avascular preperitoneal space. However, neither the unilateral posterior McEvedy approach nor the anterior approach does, as only part of the musculature and fasciae are retracted. The inferior epigastric vasculature and posterior lamina transversalis fascia, which remain in situ, block the view. Unless they are disrupted or circumvented, neither of the latter approaches or subsequent repairs should be labeled preperitoneal. 相似文献
33.
目的观察瑞芬太尼对人肠系膜小动脉平滑肌细胞(MASMCs)L-型钙通道电流的影响,探讨其扩张血管的机制。方法酶解法分离人肠系膜小动脉单个平滑肌细胞,采用全细胞膜片钳技术,以钡电流作为载流子,观察19.4nmol/L瑞芬太尼在不同钳制电压下以及不同浓度瑞芬太尼在最大激活电压下对MASMCs L-型钡电流(TBa-L)的影响。结果19.4 nmol/L瑞芬太尼可抑制TBa-L,使电流密度-电压曲线上移,最大激活电压及翻转电压均向膜的负电位方向移动(P<0.01)。瑞芬太尼浓度依赖性地抑制TBa-L,其半数最大抑制效应的浓度为(39±4)nmol/L。结论瑞芬太尼浓度依赖性地抑制人肠系膜小动脉平滑肌细胞L-型钙通道,从而产生扩张血管的作用。 相似文献
34.
Louis G. Martin M.D. Randy D. Cork James O. Wells 《Cardiovascular and interventional radiology》1993,16(2):76-80
Two hundred forty-four consecutive patients (mean age 61 years), including 123 who had technically valid renal vein renin
(RVR) analysis and 121 without RVR data, underwent technically successful percutaneous renal artery angioplasty (PTRA). They
were retrospectively examined to evaluate the utility of RVR analysis in identifying renal hypertension (RVH), predicting
benefit from PTRA, and determining if the lack of knowledge of renin levels significantly affected clinical outcome after
PTRA. Abnormal RVR values were associated with clinical benefit after PTRA in 62 of 93 patients (67% sensitivity, 20% specificity,
72% positive predictive value). Clinical improvement following PTRA occurred in 31 of 37 patients with normal pre-PTRA RVR
values (16% negative predictive value). RVR analysis correctly identified 86 of 117 patients with renovascular hypertension
(74% sensitivity, 16% negative predictive value). Improved blood pressure (BP) control occurred in 72% with abnormal RVR analysis
and 66% of the 121 patients without RVR data (p>0.1). We conclude that the very low negative predictive value significantly
limited the use of RVR analysis in this elderly (mean age 60 years) patient population with a high incidence of mild renal
functional impairment (mean serum creatinine 1.4 mg/dl) and bilateral renal artery stenosis (38%). The lack of pre-PTRA renin
data did not significantly affect clinical outcome. If RVR data were relied upon as the exclusive selection criterion in patients
of this type, many would be prevented from having the benefit of cure or improvement by PTRA. 相似文献
35.
目的 分析局部动脉粥样硬化不稳定斑块对其余动脉粥样硬化斑块形成的影响。方法 选取体质量年龄适合的新西兰白兔30只,按照随机数字表法将其随机分为3组(n=10)。实验组和对照组予以高脂饲料喂养,空白组予以普通饲料喂养。喂养4周后,对实验组采用颈动脉球囊损伤术进行动脉粥样硬化建模,12周后杀死兔子,取颈动脉、腹主动脉进行病理组织学检测,利用图像分析软件测量各部位平均内膜厚度、斑块面积与管腔面积之比,同时抽取兔子静脉血行血脂分析。结果 4周末、8周末、12周末时,实验组、对照组体质量较0周时明显升高(P<0.05),空白组体质量较0周时无明显差异(P>0.05),且空白组体质量明显低于实验组、对照组(P<0.05),对照组间体质量比较无明显差异(P>0.05);实验组平均内膜厚度明显大于对照组、空白组(P<0.05),且实验组手术侧颈动脉平均内膜厚度、斑块面积与管腔面积明显大于对侧颈动脉、腹主动脉(P<0.05);12周末时,实验组、对照组甘油三酯(TG)、总胆固醇(TC)、低密度胆固醇(LDL-C)、高密度胆固醇(HDL-C)、超敏C反应蛋白(CRP)水平明显高于空白组(P<0.05),且对照组间TG、TC、LDL-C、HDL-C、CRP水平比较无明显差异(P>0.05),实验组CRP水平明显高于对照组(P<0.05)。结论 局部动脉粥样硬化不稳定斑块可使机体CRP水平升高,进而促进其余动脉粥样硬化斑块的形成。 相似文献
36.
Ichiro Ikegaki Yoshio Suzuki Shin-ichi Satoh Toshio Asano Masato Shibuya Kenichiro Sugita 《Naunyn-Schmiedeberg's archives of pharmacology》1989,340(4):431-436
Summary The effects of calcitonin gene-related peptide (CGRP) on canine cerebral arteries and on vertebral blood flow were investigated in-vivo and in-vitro and the findings compared with the effects of vasoactive intestinal peptide (VIP) and substance P. Administration of CGRP into the vertebral artery caused a dose-dependent and long-lasting increase in blood flow. The in-vivo vasodilatory effects of substance P and VIP were short-lasting. CGRP (0.1 to 100 nmol/l) elicited a concentration-dependent relaxation of the isolated middle cerebral and basilar arteries when the tissues were precontracted by exposure to prostaglandin F2 (PGF2). This effect was not antagonized by propranolol, atropine, tetrodotoxin, (N-Ac-Tyr1, D-Phe2)-growth hormone-releasing factor(1–29)-NH2 or (D-Pro2, D-Trp7,9) substance P. CGRP also reduced concentration-dependently the contraction of cerebral arteries induced by KCl or 9,11-epithio-11,12-metano-thromboxane A2 (STXA2). Mechanical removal of the endothelium did not abolish the vasodilatory response to CGRP. In PGF2-contracted canine cerebral arteries, VIP (0.1 to 100 nmol/l) was less potent a vasodilator than CGRP. At low concentrations (0.01 to 1 nmol/l) substance P elicited a rapid and short-lasting relaxation, and in the absence of endothelium this relaxation disappeared. These findings are clear evidence that CGRP modulates vascular tone. 相似文献
37.
Summary In rabbit jejunal arteries, the membrane potential of single smooth muscle cells decreased on the application of noradrenaline 3 mol/1. LY 171555 1 mol/1 did not change, whereas SKF 38393 10 mol/1 reversed the effect of noradrenaline. When prostaglandin F2 (PGF2) was used to evoke depolarization in the presence of prazosin 0.1 mol/1, rauwolscine 1 mol/1 and propranolol 1 mol/1, both SKF 38393 10 mol/1 and dopamine 10 mol/1 repolarized the membrane. SCH 23390 1 mol/1 antagonized the effects of SKF 38393 10 mol/1 and dopamine 10 mol/1. Thus, the change in membrane potential is mediated by a DA1-recep-tor. 相似文献
38.
Min Huang 《中国生物医学工程学报(英文版)》1998,(1)
INTRODUCTIONWhenpulsatingbloodflowsthroughtheartery,thearterialwallwilldilateandcontractperiodicallybecauseoftheelasticityofarterialwallandtheperipheralresistance'Thisensuresthecontinuityofbloodflowandthelocalbloodpressurenotchangingtoomuch.Ifthearterialwallispathologicallychanged,causingthechangeoftheelasticityofarterialwall,theperformanceofarterywillbeaffected'Atpresent,thecomplianceiswidelyusedtoevaluatethedistensibilityofarterialwass[1],butitcannotevaluatethetotalperformanceofartery'T… 相似文献
39.
J. Pillet B. Enon P. Cronier Ph. Mercier P. Moreau J. M. Chevalier 《Surgical and radiologic anatomy : SRA》1982,4(4):307-314
Summary The arteries of the gut, and in particular in the inferior mesenteric artery (a. mesenterica inferior), normally play a minimal role in supplying blood to the lower limbs. However, this is far from being the case in aorto-iliac obstruction. The anatomical anastomoses between the intestinal arterial system and the arteries of the lower limb hypertrophy and in one case out of ten become predominant.In the present study the path taken and the relations of the collaterals of the intestinal arteries and of their anastomoses have been traced, and several collateral pathways are described.
Rôle des artères mésentériques dans la revascularisation artérielle des membres inférieurs
Résumé Les artères digestives, et en particulier l'artère mésentérique inférieure (a. mesenterica inferior), jouent à l'état normal un rôle minime dans la vascularisation des membres inférieurs. Il n'en est pas de même en cas d'oblitération aorto-iliaque. Les anastomoses anatomiques entre le système artériel digestif et les artères du membre inférieur s'hypertrophient et, dans un cas sur 10, deviennent prédominantes.Dans cette étude, le trajet et les relations des collatérales des artères digestives et leurs anastomoses sont étudiés. Plusieurs voies collatérales sont possibles.相似文献
40.
M. MASPERS J. BJ
RNBERG P.-O. GRNDE S. MELLANDER 《Acta physiologica (Oxford, England)》1990,138(4):509-521
The sympathetic nervous control of the vascular bed of cat gastrocnemius muscle was studied with a new whole-organ technique which permits simultaneous, continuous and quantitative measurements of capillary pressure (Pc), capillary fluid exchange and resistance reactions in the whole vascular bed and in its three consecutive sections: large-bore arterial vessels (> 25 μm), arterioles (< 25 μm) and veins. The results demonstrated a distinct neural control of all three consecutive vascular sections, graded in relation to the rate of nerve excitation up to maximum at 16 Hz. Stimulation at high rates, which in the steady state caused an average rise of overall regional resistance from 15.3 to 120 PRU (7.8-fold increase), thus raised large-bore arterial vessel resistance from 8.8 to 64 PRU (7.3-fold increase), arteriolar resistance from 4.5 to 49 PRU (10.9-fold increase) and venous resistance from 2.0 to 7 PRU (3.5-fold increase). The rate of resistance development (PRU s-1) of the sympathetic constrictor response was much higher in the arteriolar than in the other sections, which indicates that the neural control is especially prompt and efficient in the arterioles. A passive component was shown to contribute to the described responses only on the venous side, but in no case by more than 10% of the total sympathetic venous resistance response, which thus is mainly active. Of special functional importance was that the new technique provided information about the adrenergic control of Pc, in absolute figures. From the control value of 19 mmHg, graded sympathetic stimulation caused a graded decline in Pc, at maximum constriction by about 7 mmHg. This resulted in marked net transcapillary fluid absorption, in turn increasing plasma volume. 相似文献