全文获取类型
收费全文 | 180151篇 |
免费 | 13041篇 |
国内免费 | 4218篇 |
专业分类
耳鼻咽喉 | 1357篇 |
儿科学 | 2535篇 |
妇产科学 | 3059篇 |
基础医学 | 23531篇 |
口腔科学 | 3365篇 |
临床医学 | 12476篇 |
内科学 | 23102篇 |
皮肤病学 | 2192篇 |
神经病学 | 12033篇 |
特种医学 | 6442篇 |
外国民族医学 | 2篇 |
外科学 | 14582篇 |
综合类 | 24344篇 |
现状与发展 | 21篇 |
一般理论 | 8篇 |
预防医学 | 14913篇 |
眼科学 | 2281篇 |
药学 | 25428篇 |
55篇 | |
中国医学 | 12585篇 |
肿瘤学 | 13099篇 |
出版年
2024年 | 339篇 |
2023年 | 2207篇 |
2022年 | 4709篇 |
2021年 | 7523篇 |
2020年 | 6082篇 |
2019年 | 6038篇 |
2018年 | 6095篇 |
2017年 | 6756篇 |
2016年 | 6812篇 |
2015年 | 6370篇 |
2014年 | 7128篇 |
2013年 | 11033篇 |
2012年 | 8952篇 |
2011年 | 10817篇 |
2010年 | 6744篇 |
2009年 | 6855篇 |
2008年 | 8368篇 |
2007年 | 9333篇 |
2006年 | 8880篇 |
2005年 | 8230篇 |
2004年 | 7064篇 |
2003年 | 6319篇 |
2002年 | 4989篇 |
2001年 | 4491篇 |
2000年 | 3759篇 |
1999年 | 3200篇 |
1998年 | 2494篇 |
1997年 | 2601篇 |
1996年 | 2396篇 |
1995年 | 2061篇 |
1994年 | 2007篇 |
1993年 | 1684篇 |
1992年 | 1546篇 |
1991年 | 1461篇 |
1990年 | 1258篇 |
1989年 | 1028篇 |
1988年 | 987篇 |
1987年 | 897篇 |
1986年 | 829篇 |
1985年 | 1207篇 |
1984年 | 967篇 |
1983年 | 729篇 |
1982年 | 752篇 |
1981年 | 618篇 |
1980年 | 601篇 |
1979年 | 477篇 |
1978年 | 297篇 |
1977年 | 259篇 |
1976年 | 244篇 |
1975年 | 186篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
881.
选用产期接近的3月龄小尾寒羊30只,随机分为二组(试验Ⅰ、试验Ⅱ),每组15只。试验Ⅰ饲喂本场加工的羔羊精饲料,试验Ⅱ饲喂本场加工的羔羊精饲料基础上,每公斤饲料中分别添加钴0.4mg和维生素B120.30mg,试验结果表明:试验Ⅰ与试验Ⅱ日增重相比差异极显著(P<0.01)。 相似文献
882.
Hiroshi Yamada Shizuo Oi Norihiko Tamaki Satoshi Matsumoto Katsuko Sudo 《Child's nervous system》1992,8(7):394-398
Primary aqueductal stenosis is one of the main causes of congenital hydrocephalus in humans and experimental models. The congenitally hydrocephalic rat strain LEW/Jms is one such model. In this report, we describe further detailed histological features of periaqueductal structure, including the posterior commissure, subcommissural organ (SCO), and ependyma, and discuss the changes in these structures in relation to the cause of hydrocephalus. Coronal sections of the aqueduct in normal rats showed that the usual ependyma was absent in the center of the base facing the dorsal side, which was replaced by tall columnar cells. On the other hand, in hydrocephalic rats the ependyma encircled the aqueductal cavity. In midline sagittal sections, normal and hydrocephalic rats showed the SCO, although the SCO in hydrocephalic rats was shorter than in normal rats. There was also a marked difference between normal and hydrocephalic rats in the dorsoventral dimension of the rostral midbrain. In hydrocephalus, this dimension was large in comparison with normal rats. The superior collicular commissure located caudal to the posterior commissure ran along the ventral side of the midbrain in rats with hydrocephalus, and there was a cell-depleted area just dorsal to the superior collicular commissure. The same findings were observed from the 17th day of gestation until the postnatal period. Although the role of the SCO has been widely discussed from the viewpoint of secretory function, the present study indicated that this organ might be involved in the formation of the shape of the aqueduct. 相似文献
883.
本文报告65例双炔失碳酯配伍d1-15甲基PGF_(2α)(以下简称PG)抗早孕结果并与33例丙睾配伍PG抗早孕结果进行比较。结果显示,双炔失碳酯组完全流产59例,占90%;不全流产3例,占5%;失败3例,占5%;总有效率95%。丙睾组完全流产27例,占82%;不全流产6例,占18%;总有效率100%。两组总有效率无显著差异;完全流产率无显著差异;但不全流产率有明显差异(P<0.05)。药流后点滴出血天数,双炔失碳酯组平均为8.1±5.0天;丙睾组平均为18.9±19.1天;两组有明显差别(P<0.05)。双炔失碳酯经阴道给药后无一例发生心、肝、肾功能变化。 相似文献
884.
应用银染技术,对24例结肠腺癌Ⅱ级不典型增生,30例绒毛状腺瘤,14例绒毛状腺瘤Ⅲ级不典型增生和29例高分化管状腺癌进行银染核仁形成区嗜银蛋白(Ag-NORs)定量研究,观察Ag-NORs数量、形态、大小和分布在结肠肿瘤交界性病变中的表达.提示Ag-NORs四项指标定量研究对结肠脉瘤,特别是Ⅲ级不典型增生与绒毛状腺瘤之结肠癌前病变有较好的监测作用. 相似文献
885.
应用拉丁方设计,在不同体重组的大鼠,于不同时辰,对交叉上核采取不同强度的刺激,用放射免疫法测定外周血中皮质酮的含量。其结果显示:各体重组间无显著性差异,不同时辰血浆皮质酮的平均含量各组呈现基本相同的节律性变化,无论何时辰刺激交叉上核使之兴奋,均可显著提高血浆皮质酮的含量。完全损毁交叉上核后72小时血浆皮质酮含量和正常对照组无显著性差异,且其节律性也没有出现明显变化。 相似文献
886.
Judith L. Black Peter R. A. Johnson Lorraine Alouan Carol L. Armour 《European journal of pharmacology》1990,180(2-3):311-317
This study investigated the effects of neurokinin A (NKA) on cholinergic neural responses in human bronchus. NKA (0.1 nM) did not alter the contractile response to submaximal electrical field stimulation. However, K+ channel blockade with 4-aminopyridine (4-AP) (0.1 mM) potentiated the response to electrical field stimulation (to 182 ± 25% of control, n = 4, P < 0.05) and subsequent addition of NKA in the presence of 4-AP produced further potentiation (to 123 ± 6% of the response to 4-AP n = 4, P < 0.05). Neither 4-AP (0.01 or 0.1 mM) nor NKA in the presence of 4-AP potentiated the actions of exogenous acetylcholine but in these experiments 4-AP itself produced a marked direct contractile response. Thus NKA in the presence of K+ channel blockade potentiates cholinergic neural response in human bronchus and this occurs at a prejunctional site. 相似文献
887.
Michael Weller Helmut Wilhelm Norbert Sommer Johannes Dichgans Horst Wiethölter 《Journal of neurology》1992,239(4):231-234
Summary Two patients are described with the triad of tonic pupil, hyporeflexia and segmental anhidrosis (Ross syndrome). Only 18 cases of this syndrome have been reported in the literature so far. While tonic pupil and reduced sweating can be attributed to the affection of postganglionic cholinergic parasympathetic and sympathetic fibres projecting to the iris and sweat glands, respectively, the pathogenesis of diminished or lost tendon jerks remains obscure. To identify the characteristic clinical features, the previous cases of Ross syndrome are reviewed. Recent evidence of subclinical disturbances of sweating in most patients with Adie's syndrome, i.e. tonic pupil and areflexia, casts doubt on the nosological concept of Ross syndrome as a distinct clinical entity. 相似文献
888.
D. MacDonald E. Lau E. L. P. Chan T. Mak J. Woo P. C. Leung R. Swaminathan 《Calcified tissue international》1992,51(6):412-414
Summary Serum intact parathyroid hormone (PTH), 25 hydroxyvitamin D(25OHD), 1,25 dihydroxyvitamin D (1,25(OH)2D), albumin, and ionized calcium were measured in 61 Chinese female patients with hip fracture and 61 control subjects. Hip fracture patients had low albumin, ionized calcium, and 250HD levels. Serum PTH and 1,25 (OH)2D values were not different between the two groups. We conclude that although 250HD level in hip fracture patients is low, there is no evidence of secondary hyperparathyroidism, suggesting that the low 250HD levels may be a secondary phenomenon in response to the fracture. 相似文献
889.
890.