全文获取类型
收费全文 | 35251篇 |
免费 | 1640篇 |
国内免费 | 1173篇 |
专业分类
耳鼻咽喉 | 173篇 |
儿科学 | 390篇 |
妇产科学 | 217篇 |
基础医学 | 5595篇 |
口腔科学 | 573篇 |
临床医学 | 2217篇 |
内科学 | 3318篇 |
皮肤病学 | 67篇 |
神经病学 | 5600篇 |
特种医学 | 626篇 |
外科学 | 3067篇 |
综合类 | 6431篇 |
现状与发展 | 1篇 |
预防医学 | 1579篇 |
眼科学 | 539篇 |
药学 | 4935篇 |
中国医学 | 2003篇 |
肿瘤学 | 733篇 |
出版年
2023年 | 179篇 |
2022年 | 443篇 |
2021年 | 526篇 |
2020年 | 540篇 |
2019年 | 461篇 |
2018年 | 524篇 |
2017年 | 612篇 |
2016年 | 715篇 |
2015年 | 682篇 |
2014年 | 1377篇 |
2013年 | 1742篇 |
2012年 | 1629篇 |
2011年 | 1776篇 |
2010年 | 1623篇 |
2009年 | 1592篇 |
2008年 | 1674篇 |
2007年 | 1793篇 |
2006年 | 1808篇 |
2005年 | 1647篇 |
2004年 | 1518篇 |
2003年 | 1435篇 |
2002年 | 1236篇 |
2001年 | 1112篇 |
2000年 | 953篇 |
1999年 | 784篇 |
1998年 | 889篇 |
1997年 | 826篇 |
1996年 | 735篇 |
1995年 | 744篇 |
1994年 | 578篇 |
1993年 | 498篇 |
1992年 | 470篇 |
1991年 | 443篇 |
1990年 | 385篇 |
1989年 | 304篇 |
1988年 | 281篇 |
1987年 | 224篇 |
1986年 | 336篇 |
1985年 | 613篇 |
1984年 | 494篇 |
1983年 | 353篇 |
1982年 | 342篇 |
1981年 | 295篇 |
1980年 | 228篇 |
1979年 | 134篇 |
1978年 | 120篇 |
1977年 | 82篇 |
1976年 | 78篇 |
1975年 | 47篇 |
1974年 | 56篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
Endotoxin-induced uveitis (EIU) in the rat: A study of inflammatory and immunological mechanisms 总被引:2,自引:0,他引:2
Endotoxin-induced uveitis (EIU) can be produced by systemic injection of endotoxin (ET). It is not clear yet why exclusive ocular involvement occurs in this model. To clarify this question and to establish the sequence of inflammatory events, EIU was induced in Lewis rats by footpad injection of Salmonella ET. Ocular inflammatory response (anterior chamber cells and proteins), aqueous inflammation mediators (thromboxane B2, prostaglandin E2, leukotriene B4 and substance P) and MHC class 2 (Ia) antigen expression in the ciliary body were monitored for 72 hours. Thromboxane B2 was detected early in the aqueous humor, peaking already 1 hour after ET injection. Prostaglandin E2 & leukotriene B4 peaks and a second peak of thromboxane B2 were recorded 18 hours after ET-injection, at the time of maximal ocular inflammation. MHC-class 2 expression was first detected in the ciliary body stroma at the vascular level 6 hours after ET injection and was massively expressed in the ciliary body epithelium at 18 and 72 hours. It is hypothetized that ciliary body endothelium is particularly sensitive to the effect of ET and is the site of thrombocyte adherence. Vascular damage leads in succession to cellular infiltration, release of inflammation mediators and disruption of blood-ocular barrier. MHC-class 2 expression is a secondary phenomenon and is probably at the origin of additional tissue damage from immune effector mechanisms. 相似文献
42.
Iwar Klime Antonian Vraana Jaroslav Kune Elena eboUkovaA Zdena Dobe ovaa Pavel tolba Josef Zicha 《Blood pressure》1995,4(3):137-142
Hereditary hypertriglyceridemic rats (hHTg) were developed as a new genetic model for the study of relationships between blood pressure (BP) and metabolic abnormalities. This strain has been produced by selective inbreeding from Wistar rats according to the rise of plasma triglycerides induced by a high-sucrose diet. Though hHTg rats display hypertriglyceridemia, impaired glucose tolerrance, hyperinsulinemia, insulin resistance and increased BP even without nutritional stimuli, high sucrose feeding further aggravates these symptoms. High plasma triglycerides levels in hHTg rats seem to be a consequence of their hyperproduction. Impaired insulin action is responsible for the defective glucoregulation in this strain. The loss of insulin responsiveness might be due to a reduction in the number of glucose transporters. Highly significant relationships among plasma triglycerides, ouabain-resistant Na+ transport and BP were demonstrated in the hHTg rats. Segregating populations (F2 hybrids) should be used for genetic analysis of the primary role of lipid and/or ion transport abnormalities in the pathogenesis of this form of genetic hypertension. 相似文献
43.
Changes of Intestinal Caicitonin Gene-related Peptide in Acute Intestinal Radiation Sickness in Rats
The characteristic distribution of calcitonin gone-related peptide(CGRP)inthe small intestine of rats and its changes in acute intestinal radiation sickness(AIRS)were studied with immunocytochemistry(whole mount stretch preparations of the smallintestine and cryostat sections)and radio-immunoassay.It was found that in all the lay-ers of the intestinal walls,there were large amounts of CGRP immunoreactive(CGRP-I)nerve fibers which existed in especiaUy high density in the myenteric,submucosal andmucosal plexuses.There was also a rather high density of the nerves around the smallvessels of the small intestine and the intestinal crypts.Some CGRP-I neurons were seenin the myenteric and submucosal plexuses.In AIRS,the intestinal CGRP showed a dip-hasic change,in a lower level in the 24th h and a higher level in the 48th and 72nd h af-ter irradiation.The results indicate that CGRP may be related to the regulation of the motility,se-cretion,absorption,sensation,and regional blood flow of the gastrointestinal tract.Pro-bably,CGRP is released under the stress of AIRS and participates in the mechanism ofinjury through many ways especially through the influence on the regional blood flowand the increase of the permeability of blood vessels. 相似文献
44.
The best anastomotic agent to join nerve ends is controversial. This paper describes a controlled trial between a collagen tube wrap and a tissue glue to anastomose the rat facial nerve. There was no difference in the results using photographic, histological and electrophysiological techniques. 相似文献
45.
Abstract: The effects of pyridoxalated hemoglobin polyoxyethylene conjugate (PHP) and stroma-free hemoglobin (SFH) on vascular responsiveness to various vasoactive substances were examined in isolated perfused rat kidneys. The kidneys isolated from rats were perfused with 6% PHP, 6% SFH, and 6% hydroxyethylstarch (HES) solution at a constant flow rate. Vascular responsiveness to acetylcholine (ACh), nitroglycerin (NG), norepinephrine (NE), and angiotensin-II (ANG-II) was examined by measuring the perfusion pressure (PP). Effects of inhibition of endothelium-derived relaxing factor (EDRF) by NG -monomethyl L-arginine (L-NMMA) on NE-induced and ANG-II-induced renal vascular responses were examined. ACh and NG induced a dose-dependent decrease in perfusion pressure (PP) in all groups. NE and ANG-II induced an increase in PP in all groups, but NE-induced and ANG-II-induced responses in the PHP-perfused and SFH-perfused groups were significantly larger than those in the HES-perfused group. L-NMMA did not alter vascular responsiveness to NE and ANG-II. These results indicate that PHP and SFH do not inhibit EDRF induced by ACh, but hemoglobin moiety per se does augment the vascular responsiveness to NE and ANG-II in the isolated perfused rat kidney. 相似文献
46.
Piotr Kozlowski Alastair M. Buchan Ursula I. Tuor Dong Xue Zhi-Gao Huang Karen E. Chaundy John K. Saunders 《Magnetic resonance in medicine》1997,37(3):346-354
31P, 1H and lactate spectroscopic imaging was used to evaluate the effects of hypothermia on focal cerebral ischemia produced by middle cerebral artery occlusion. The effects on high energy phosphate metabolism, pH, lactate and NAA were investigated in 24 spontaneously hypertensive rats subjected to either permanent or transient ischemia. Under either normothermic (37.5°C) or hypothermic (32°C) conditions, with permanent 6-h occlusion, there was little difference between groups in either the NMR measurements or the volume of infarction. In animals that underwent 3 h of ischemia followed by 12 h of reperfusion, the ischemic changes in lactate, pH, NAA, and high-energy phosphate returned toward control values, and there was a protective effect of hypothermia (infarct volume of 211 ± 26 and 40 ± 14 mm3 in normothermic and hypothermic groups, respectively). Thus, hypothermia did not ameliorate the changes in lactate, pH, NAA, or high energy phosphate levels occurring during ischemia, however, during reperfusion there was an improvement in both the recovery of these metabolites and pathological outcome in hypothermic compared with normothermic animals. 相似文献
47.
目的:观察缺氧及停止缺氧后对大鼠心肌血流量的影响。方法:34只Wistar大鼠,随机分为4组:①平原对照组;②急性缺氧组;③慢性缺氧组;④返回平原组。以放射性生物微球法测定心肌血流量。结果:急性缺氧引起PaO2、心输出量及氧运送量降低,但左、右心室心肌血流量明显增加;慢性缺氧时右心室收缩压、血球压积、血液粘滞性及右心室生理指数明显增加,而心肌血流量接近正常。停止缺氧30d后,上述所有指标均与平原以 相似文献
48.
在微量注射大量肝脏mRNA之后,通过电压箝方法进行功能鉴定,两栖类卵母细胞成功地表达了AVPV1a受体。但在灌流AV4-8溶液时,却不能诱导卵母细胞产生内向振荡电流反应。提示AVP4-8不能通过AVPV1a受体而介导生理学效应。 相似文献
49.
HemorrhagicfeverwithrenalsyndromevirusinfectioninliversstudiedbyinsituhybridizationandimmunohistochemistryYangShoujing(杨守京);L... 相似文献
50.
Shigeharu Kimura Yoshimi Ohshige Liping Lin Tadashi Okumura Chizuko Yanaihara Noboru Yanaihara† Yahe Shiotani 《Journal of neuroendocrinology》1994,6(5):503-507
The localization of pituitary adenylate cyclase-activating polypeptide (PACAP) in the hypothalamus-pituitary system in rats was examined in light and electron microscopic immunocytochemistry using a specific antiserum to synthetic PACAP 1–38 (R0831). In light microscopic study, intensely PACAP-immunostained perikarya were observed in the supraoptic and paraventricular magnocellular nucleus in the hypothalamus. In the median eminence, many immunoreactive nerve fibers were observed in the internal layer, but a few immunoreactive terminals were noticed in the external layer. In the pituitary gland, numerous immunoreactive nerve fibers were observed in the posterior lobe. In the intermediate lobe, moderately immunostained cells were observed, but in the anterior lobe no immunostained cells were noticed. In electron microscopic study, PACAP-immunoreactivity was examined by avidin-biotin peroxidase complex method. In the perikarya of the supraoptic and paraventricular magnocellular nucleus, DAB-reaction products were distributed diffusely in the cytoplasmic matrix, frequently attaching to the rough-surfaced endoplasmic reticulum. In the nerve terminals of the posterior lobe, reaction products were observed among the secretory granules, but sometimes upon them. In the cells of the intermediate lobe, reaction products were also distributed in the cytoplasmic matrix. 相似文献