全文获取类型
收费全文 | 4091429篇 |
免费 | 342760篇 |
国内免费 | 38213篇 |
专业分类
耳鼻咽喉 | 55333篇 |
儿科学 | 121333篇 |
妇产科学 | 103171篇 |
基础医学 | 624376篇 |
口腔科学 | 106683篇 |
临床医学 | 387001篇 |
内科学 | 731194篇 |
皮肤病学 | 103460篇 |
神经病学 | 340686篇 |
特种医学 | 157935篇 |
外国民族医学 | 765篇 |
外科学 | 620112篇 |
综合类 | 160042篇 |
现状与发展 | 168篇 |
一般理论 | 2391篇 |
预防医学 | 325518篇 |
眼科学 | 97079篇 |
药学 | 292009篇 |
357篇 | |
中国医学 | 28559篇 |
肿瘤学 | 214230篇 |
出版年
2022年 | 35675篇 |
2021年 | 70955篇 |
2020年 | 48400篇 |
2019年 | 68272篇 |
2018年 | 84599篇 |
2017年 | 66708篇 |
2016年 | 72097篇 |
2015年 | 90267篇 |
2014年 | 130066篇 |
2013年 | 192370篇 |
2012年 | 126853篇 |
2011年 | 130846篇 |
2010年 | 137170篇 |
2009年 | 138857篇 |
2008年 | 109082篇 |
2007年 | 112820篇 |
2006年 | 123405篇 |
2005年 | 117402篇 |
2004年 | 112178篇 |
2003年 | 101415篇 |
2002年 | 89615篇 |
2001年 | 143696篇 |
2000年 | 138614篇 |
1999年 | 131570篇 |
1998年 | 74189篇 |
1997年 | 70746篇 |
1996年 | 67239篇 |
1995年 | 62162篇 |
1994年 | 55305篇 |
1993年 | 50915篇 |
1992年 | 88583篇 |
1991年 | 83241篇 |
1990年 | 78349篇 |
1989年 | 77027篇 |
1988年 | 70625篇 |
1987年 | 68750篇 |
1986年 | 64433篇 |
1985年 | 63429篇 |
1984年 | 55288篇 |
1983年 | 49624篇 |
1982年 | 44021篇 |
1981年 | 41041篇 |
1980年 | 38582篇 |
1979年 | 44823篇 |
1978年 | 38211篇 |
1977年 | 34685篇 |
1976年 | 31403篇 |
1975年 | 30148篇 |
1974年 | 31615篇 |
1973年 | 30435篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Frances J. Mather Richard M. Simon Gary M. Clark Daniel D. 《Statistics in medicine》1990,9(9):1118-1118
992.
W J Scott C A Duggan C M Schreiner M D Collins 《Toxicology and applied pharmacology》1990,103(2):238-254
The effects of acetazolamide on the developing rodent limb bud were postulated to result from a reduction of intracellular pH (pHi). Embryonic intracellular pH was calculated from transplacental distribution of the weak acid, 5,5'-dimethyloxazolidine-2,4-dione, in teratogenically sensitive (C57BL/6) and resistant (SWV) inbred mice. pHi was reduced by acetazolamide treatment in C57 embryos and limb buds but not in SWV samples. Acetazolamide teratogenesis can be exacerbated by coadministration of amiloride, presumably through inhibition of Na+/H+ exchange attributable to the latter agent. pHi reduction after such treatment was more profound than after acetazolamide alone, providing further support for the central hypothesis. pH was also reduced in other embryonic (embryo plasma) and extraembryonic compartments (exocoelomic fluid, amniotic fluid). pH changes in these compartments could also lead or contribute to abnormal development. 相似文献
993.
A Michel C Vons S Hillaire P Icard G Hazebroucq F Kemeny D Houssin D Franco 《European surgical research. Europ?ische chirurgische Forschung. Recherches chirurgicales européennes》1990,22(5):249-255
The efficiency of Eurocollins or modified University of Wisconsin (UW) solution (MUW) in preserving rat livers was compared. After cold storage with one of the solutions, the livers were transplanted or perfused by collagenase for isolation of hepatocytes. Five of the 6 rats receiving a graft preserved with MUW versus none of the 6 rat receiving a graft preserved with Eurocollins solution survived 24 h or more. A significantly greater number of hepatocytes were isolated from livers preserved with MUW than from livers preserved with Eurocollins solution. This suggests a better reperfusion of MUW-preserved livers by collagenase resulting from less endothelial injury. LDH release by cultured hepatocytes, ketone body production and stimulation by glucagon were not significantly different between the two groups. These results confirm the superiority of MUW solution over Eurocollins in preserving liver grafts. They suggest that the advantage of MUW solution results from better protection of vascular endothelium rather than of hepatocytes. 相似文献
994.
Reversal of diabetes in BB rats by transplantation of encapsulated pancreatic islets 总被引:8,自引:0,他引:8
Prolonged survival of pancreatic islet allografts implanted in diabetic BB rats was achieved by encapsulation of individual islets in a protective biocompatible alginate-polylysine-alginate membrane without immunosuppression. Intraperitoneal transplantation of the encapsulated islets reversed the diabetic state of the recipients within 3 days and maintained normoglycemia for 190 days. Normal body weight and urine volume were maintained during this period, and no cataracts were detected in the transplant recipients. In contrast, control rats receiving transplants of unencapsulated islets experienced normoglycemia for less than 2 wk. These results demonstrated that microencapsulation can protect allografted islets from both graft rejection and autoimmune destruction without immunosuppression in an animal model that mimics human insulin-dependent diabetes. 相似文献
995.
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
996.
Seventy patients, aged 1–20 years, were seen at Jordan University Hospital with high blood pressure (BP) over a 3-year period. BP values ranged from 140 to 230 mmHg for systolic pressure and from 90 to 130 mmHg for diastolic pressure. Essential hypertension was seen in only 6 patients (8.6%); secondary hypertension (n=64 or 91.4%) was due to renal parenchymal diseases (RPD) in 46 patients (65.7%), reno-vascular lesions in 8 (11.4%), renal transplantation in 5 (7.2%), teenage pregnancy in 4 (5.7%), and phaeochromocytoma in 1 patient (1.4%). The aetiologies of RPD were as follows: end-stage renal disease requiring dialysis in 14 patients, acute glomerulonephritis in 14, idiopathic nephrotic syndrome in 10, chronic renal insufficiency in 5, and polycystic kidney in 3 patients. Surgical cure of hypertension was achieved in 5 of the children with reno-vascular lesions and in the patient with phaeochromocytoma. 相似文献
997.
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
998.
Summary Intracavitary application of ultrasound was first performed for diagnostic purposes in 1967; since that time, it has been
more and more widely used. As far as the gastrointestinal tract is concerned, endoscopically controlled ultrasonic probes
provide visualization of the various layers of the intestinal wall. It is therefore possible to describe lesions of the esophagus,
stomach, and the rectum with regard to their nature and depth of infiltration. Furthermore, periesophageal and perigastric
organs can be visualized. It has become evident that endosonography is particularly important for pretherapeutic staging of
tumors of the esophagus, stomach, and rectum. Here prospective comparative studies confirm the superiority of this new diagnostic
procedure when compared to the methods available to date. 相似文献
999.
It has become common practice to rely on fitted estimates ofapparent in vivo metabolic constants (e.g., Vmax and KM) inparameterization of PBPK models. Yet, quantitative estimatesof precision in these fitted parameters are not routinely reported.Such information is needed to assess the reliability of modelpredictions. The purpose of this study was to assess the precisionin estimates of Vmax and KM for chloroform, accounting for boththe statistical uncertainties in parameter estimates from individualdata sets and any additional uncertainty due to differencesin the parameter estimates derived from various experiments.Joint confidence regions for Vmax and KM from each experiment,generated using maximum likelihood techniques, were used toevaluate these questions. Three previously published data setswere considered. Estimates of Vmax and KM obtained from thesedata sets differed more than could be explained as a consequenceof a limited number of observations, measurement error, or stochasticerror. Issues associated with the use of maximum likelihoodtechniques to estimate joint confidence regions, the estimationof metabolic constants from individual experiments within agas uptake study versus the full data set, the degree of overlapin the joint confidence regions for metabolic constants obtainedfrom separate data sets, and the implications for risk assessmentare discussed. 相似文献
1000.