全文获取类型
收费全文 | 779861篇 |
免费 | 54969篇 |
国内免费 | 1492篇 |
专业分类
耳鼻咽喉 | 10171篇 |
儿科学 | 25385篇 |
妇产科学 | 19236篇 |
基础医学 | 120333篇 |
口腔科学 | 21207篇 |
临床医学 | 71523篇 |
内科学 | 149651篇 |
皮肤病学 | 17037篇 |
神经病学 | 56048篇 |
特种医学 | 28346篇 |
外国民族医学 | 85篇 |
外科学 | 115638篇 |
综合类 | 16290篇 |
现状与发展 | 2篇 |
一般理论 | 224篇 |
预防医学 | 58420篇 |
眼科学 | 17646篇 |
药学 | 59091篇 |
3篇 | |
中国医学 | 2449篇 |
肿瘤学 | 47537篇 |
出版年
2021年 | 6940篇 |
2019年 | 6842篇 |
2018年 | 9544篇 |
2017年 | 7339篇 |
2016年 | 8156篇 |
2015年 | 9117篇 |
2014年 | 12431篇 |
2013年 | 18435篇 |
2012年 | 25333篇 |
2011年 | 26451篇 |
2010年 | 15448篇 |
2009年 | 14374篇 |
2008年 | 24191篇 |
2007年 | 25893篇 |
2006年 | 26177篇 |
2005年 | 24683篇 |
2004年 | 23775篇 |
2003年 | 22596篇 |
2002年 | 21874篇 |
2001年 | 37644篇 |
2000年 | 38133篇 |
1999年 | 31581篇 |
1998年 | 8651篇 |
1997年 | 7360篇 |
1996年 | 7612篇 |
1995年 | 7212篇 |
1994年 | 6650篇 |
1993年 | 6106篇 |
1992年 | 24002篇 |
1991年 | 23913篇 |
1990年 | 23223篇 |
1989年 | 22920篇 |
1988年 | 20784篇 |
1987年 | 20169篇 |
1986年 | 19218篇 |
1985年 | 18032篇 |
1984年 | 13328篇 |
1983年 | 11241篇 |
1982年 | 6367篇 |
1979年 | 12076篇 |
1978年 | 8483篇 |
1977年 | 7143篇 |
1976年 | 6895篇 |
1975年 | 7617篇 |
1974年 | 8849篇 |
1973年 | 8464篇 |
1972年 | 7932篇 |
1971年 | 7381篇 |
1970年 | 7109篇 |
1969年 | 6521篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
D A Evans B N Hamid E M Hoare 《Journal of the Royal College of Surgeons of Edinburgh》1990,35(1):33-35
Thirteen cases of primary appendicular adenocarcinoma are reported. This rare tumour usually presents as acute appendicitis. The correct diagnosis is rarely entertained before or during surgery. The main treatment choice lies between appendicectomy alone and appendicectomy followed by right hemicolectomy. There are anatomical reasons for advising the latter and survival figures from the literature tend to support this preference. The cases reported here indicate that in the period 1972-1984, in the North West Region, there was a slight preference for appendicectomy alone. The additional procedure of right hemicolectomy did not confer any clear-cut survival advantage. 相似文献
82.
Absorption mechanism and absorption site of a prodrug of L-DOPA, L-3-(3-hydroxy-4-pivaloyloxyphenyl)alanine (NB-355, 1) was investigated using rats. Prodrug 1 (0.5 mM) was taken up by intestinal tissue segments time-dependently in vitro at pH 6.0. However, the rate of uptake was less than that of L-dopa. Inhibitors of the amino acid active transport system (L-Phe, dinitrophenol, ouabain) had no effect on the uptake of prodrug 1. In the intestinal tissue segments, prodrug 1 was extensively hydrolyzed by diisopropylfluorophosphate-sensitive esterase(s). To characterize the absorption site, gastrointestinal tracts were ligated to make acute loops in situ and prodrug 1 or L-dopa was injected into the loops. L-dopa disappeared rapidly from the lumen of the jejunum. In contrast, prodrug 1 disappeared rapidly from the ileum rather than the duodenum or jejunum. From these results, it was suggested that prodrug 1 was slowly absorbed primarily from the lower small intestine. 相似文献
83.
84.
85.
Summary A case of bilateral congenital pseudarthrosis of the clavicle in a baby boy is described. The patient is fully asymptomatic, and no functional impairment is present. This is probably only the seventh case described of this rare congenital anomaly. 相似文献
86.
P Rubinstein M Walker N Mollen C Carpenter S Beckerman N Suciu-Foca R McEvoy F Ginsberg-Fellner 《Diabetes》1990,39(9):1138-1143
The gene frequencies, haplotype relative risks, and zygotic assortments of HLA-DR in three ethnically defined samples of insulin-dependent diabetes mellitus (IDDM) patients were determined in a prospective family study. Although DR3 and DR4 were positively associated with IDDM in the probands of 123 northern European, 94 Ashkenazi Jewish, and 49 New York Hispanic families, significant excess of DR*3/4 heterozygotes was observed only among the probands from families of northern European ancestry. There was also a significant decrease in the frequency of Bw62,DR4 haplotypes derived by northern European patients from their mothers compared with their fathers. This difference, together with data reported in the literature, suggests that the expressivity of the susceptible genotype(s) in IDDM patients may be modified by protective maternal effects associated with Bw62,DR4 and probably other DR4 haplotypes. Samples of IDDM patients from populations with high frequencies of these modifiers should have different DR-gene frequencies contributed by fathers and mothers, capable of accounting for the observed Hardy-Weinberg disequilibrium. We postulate that, because the mechanism of action of these modifiers is distinct from that of the susceptibility gene, the difference must be considered in devising strategies for elucidation of the mode of inheritance of the disease and for understanding the molecular nature of the susceptibility. 相似文献
87.
T Abumiya I Sayama K Asakura H Hadeishi M Mizuno A Suzuki N Yasui F Shishido K Uemura 《No shinkei geka. Neurological surgery》1990,18(9):837-844
Regional effects of craniotomy on cerebral circulation and metabolism, such as regional cerebral blood flow (rCBF), regional cerebral oxygen consumption (rCMRO2), regional oxygen extraction fraction (rOEF), and regional cerebral blood volume (rCBV) were examined by a PET (positron emission tomography) study concerning surgery that was performed on unruptured aneurysm patients. Eight patients with intracranial un-ruptured aneurysms were studied pre- and post-operatively by the 15O labelled-gas steady-state method, using HEADTOME-III. All patients underwent aneurysmal surgery performed by the transsylvian approach. There was a significant increase in the mean OEF values taken from the whole-brains of 8 patients, but there was not a significant change in CBF, CMRO2 or CBV. The increase in OEF was caused by decrease of O2 content, which was caused by post-operative decrease in the Hb value. So, this OEF increase was not the direct effect of craniotomy. In 2 patients, the rCBF and rCMRO2, in the fronto-temporal region (where craniotomy was performed) increased post-operatively. This regional effect suggests transient reactive hyperemia following compressive ischemia during the operative procedure, and metabolic demands for recovery of brain function. In 2 other patients, who had relatively low rCBFs during the pre-operative study, rCBF and rCMRO2 in the bi-frontal region had decreased more at the post-operative study. This change appears to have been caused by removal of cerebrospinal fluid and depression of the frontal lobe. From this study, it becomes evident that the regional effect of craniotomy on cerebral circulation and metabolism is not so great, when adequate microsurgical techniques are used. 相似文献
88.
89.
Aaron H. Burstein Pharm.D. William G. Reiss Pharm.D. Eric Kantor B.A. Gail D. Anderson Ph.D. 《Pharmacotherapy》1998,18(6):1271-1276
Study Objective . To characterize cytochrome P450 (CYP) 3A4 activity in premenopausal and postmenopausal women by evaluating the urinary 6-β-hydroxycortisokcortisol ratio. Design . Prospective study. Subjects . Thirteen premenopausal and 13 postmenopausal women who were healthy and not receiving drugs known to affect CYP3A4 activity. Interventions . Beginning on day 2 of menses, premenopausal women collected first morning urine samples every other day for a complete menstrual cycle. Postmenopausal women collected first morning urine every other day for 28 days. Measurements and Main Results . Mean weekly 6-β-hydroxycortisol:cortisol ratios did not differ during the phase (week) of the menstrual cycle. Daily ratios did not differ in postmenopausal women. No difference between premenopausal and postmenopausal women was found on comparing overall median ratios. Conclusion . Cytochrome P450 3A4 activity as measured by 6-β-hydroxy cortisol:cortisol ratio did not differ by week of menstrual cycle, suggesting no menstrual cycle-related changes. Menopause does not appear to be associated with differences in CYP3A4 activity, compared with premenopause. 相似文献
90.
C Niek van Dijk Ben Willem J. Mol Liesbeth S. L. Lim Rene K. Marti Patrick M. M. Bossuyt 《Acta orthopaedica》1996,67(6):566-570
We prospectively enrolled 160 consecutive patients with inversion trauma of the ankle in a diagnostic protocol that included physical examination within 2 days and at 5 days after trauma, arthrography, stress radiography, and ultrasonography. 135 patients had pathological lateral ligament laxity on the later physical examination or lateral ligament rupture diagnosed on arthrography and they were operated on. 122 of these patients had ligament ruptures.
At clinical follow-up after a minimum of half a year, all of the patients who were not operated on had stable joints without signs of previous ligament ruptures.
Delayed physical examination at 5 days after the injury led to the highest overall sensitivity (96%) and specificity (84%) for the detection of a ligament rupture. Additional diagnostic procedures, at a considerable cost, yielded little additional information. 相似文献
At clinical follow-up after a minimum of half a year, all of the patients who were not operated on had stable joints without signs of previous ligament ruptures.
Delayed physical examination at 5 days after the injury led to the highest overall sensitivity (96%) and specificity (84%) for the detection of a ligament rupture. Additional diagnostic procedures, at a considerable cost, yielded little additional information. 相似文献