全文获取类型
收费全文 | 1139224篇 |
免费 | 84030篇 |
国内免费 | 2623篇 |
专业分类
耳鼻咽喉 | 14801篇 |
儿科学 | 37167篇 |
妇产科学 | 32997篇 |
基础医学 | 160943篇 |
口腔科学 | 30218篇 |
临床医学 | 101058篇 |
内科学 | 228246篇 |
皮肤病学 | 26763篇 |
神经病学 | 93983篇 |
特种医学 | 43007篇 |
外国民族医学 | 395篇 |
外科学 | 169107篇 |
综合类 | 26259篇 |
现状与发展 | 3篇 |
一般理论 | 384篇 |
预防医学 | 88431篇 |
眼科学 | 25259篇 |
药学 | 78912篇 |
29篇 | |
中国医学 | 2667篇 |
肿瘤学 | 65248篇 |
出版年
2021年 | 8850篇 |
2019年 | 9743篇 |
2018年 | 13406篇 |
2017年 | 10204篇 |
2016年 | 11506篇 |
2015年 | 12816篇 |
2014年 | 18179篇 |
2013年 | 26864篇 |
2012年 | 36576篇 |
2011年 | 38261篇 |
2010年 | 22648篇 |
2009年 | 21673篇 |
2008年 | 35565篇 |
2007年 | 37587篇 |
2006年 | 37977篇 |
2005年 | 36701篇 |
2004年 | 35043篇 |
2003年 | 33247篇 |
2002年 | 32176篇 |
2001年 | 58351篇 |
2000年 | 59691篇 |
1999年 | 49346篇 |
1998年 | 13517篇 |
1997年 | 12383篇 |
1996年 | 12504篇 |
1995年 | 11855篇 |
1994年 | 10753篇 |
1993年 | 10065篇 |
1992年 | 36753篇 |
1991年 | 34994篇 |
1990年 | 33292篇 |
1989年 | 31819篇 |
1988年 | 29020篇 |
1987年 | 28169篇 |
1986年 | 26355篇 |
1985年 | 25009篇 |
1984年 | 19038篇 |
1983年 | 15941篇 |
1982年 | 9771篇 |
1981年 | 8594篇 |
1979年 | 16426篇 |
1978年 | 11647篇 |
1977年 | 9604篇 |
1976年 | 9051篇 |
1975年 | 9289篇 |
1974年 | 11227篇 |
1973年 | 10822篇 |
1972年 | 10153篇 |
1971年 | 9186篇 |
1970年 | 8796篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
142.
143.
144.
Rayssa de Lima Cardoso Raimunda Nonata Fortes Carvalho-Neta Antonio Carlos Leal de Castro Cássia Fernanda Chagas Ferreira Marcelo Henrique Lopes Silva James Werllen de Jesus Azevedo João Reis Salgado Costa Sobrinho Débora Martins Silva Santos 《Bulletin of environmental contamination and toxicology》2018,101(5):570-579
The quality of aquatic environments all around the world is being altered by different human activities that represent direct threat to the ecological system and the aquatic biota. This study aimed to evaluate the occurrence of histological and genotoxic alterations in Prochilodus lacustris as indicators of anthropic impacts in a lacustrine environment in northeast Brazil. The histological alterations were evaluated using the histological alteration index, and the genotoxic alterations were detected using the micronuclei test, at three sampling stations (S1, S2 and S3). The gills presented lesions with three stages of severity, with mild lesions more frequent in the specimens collected at station S1. Mild hepatic tissue lesions were the most frequent type in both areas. Micronucleus analysis showed that station S3 was the most affected. The biological responses observed indicated that the fish are under influence of environmental changes. It is important to highlight that the organisms collected at station S3 had a more compromised health status. 相似文献
145.
Behzad S. Khorashad Ghasem M. Roshan Alistair G. Reid Zahra Aghili Maliheh Dadgar Moghadam Behnaz Khazai Mehran Hiradfar Mozhgan Afkhamizadeh Nosrat Ghaemi Ali Talaei Mohammad Reza Abbaszadegan Azadeh Aarabi Samira Dastmalchi Tim C. Van de Grift 《Archives of sexual behavior》2018,47(8):2287-2298
Disorders of sex development (DSD) are congenital conditions in which the typical genetic and hormonal profiles are affected and thereby the usual process of sexual differentiation. Most of these studies, however, have been conducted in Western countries. In the present study, preschool sex-typed activities of Iranian individuals with DSD and their age-matched non-affected male and female relatives were assessed using the Pre-School Activities Inventory (PSAI) modified for retrospective self-report. A total of 192 individuals participated in our study, including 33 46,XX individuals with congenital adrenal hyperplasia (CAH; M age?=?10.36, SD?=?5.52), 15 46,XY individuals with complete androgen insensitivity syndrome (CAIS; M age?=?19.8, SD?=?7.14), and 16 46,XY individuals with 5-alpha reductase deficiency type-2 (5α-RD-2; M age?=?17.31, SD?=?7.28), as well as one age-matched non-affected male and female relative for each patient. With regard to PSAI scores, male-identifying participants with 5α-RD-2 and male controls reported similar levels of male-typical childhood play. Female-identifying participants with 5α-RD-2 and CAH showed comparable scores: significantly less masculine and more feminine than male controls, but significantly more masculine and less feminine than females with CAIS and female controls. These findings support the role of androgens in the development of sex-typical childhood play behavior, with those being exposed to higher levels of fetal functional androgens expressing more masculine behavior at preschool ages. 相似文献
146.
A Casasco A Calligaro M Casasco P Menghini C Marchetti P Poggi D R Springall J M Polak 《Archives of oral biology》1990,35(8):685-688
The occurrence and distribution of protein p38 (synaptophysin) were investigated by immunofluorescence. Immunoreactivity for protein p38-like antigen was detected within axons of radicular nerve trunks entering the tooth and within nerve terminals close to blood vessels. Immunoreactive structures were also observed in the para-odontoblastic region. It is proposed that protein p38, translocated within small synaptic vesicles from neuronal perikarya along the axons, may be a reliable marker for detection of nerve endings in human tooth. 相似文献
147.
A new, small-color-difference equation for dental shades 总被引:14,自引:0,他引:14
Traditionally, dental-shade-guide standards are designated in terms of Munsell hue (H), value (V), and chroma (C). However, delta E color differences proposed as ADA tolerances for shade guides are in the CIE L*a*b* system. The purpose of this study was to evaluate a new color-difference equation, delta EM = C delta H/5 + 7 delta V + 4 delta C for estimation of small color differences by Munsell parameters. The published values of the Bioform shade-guide tooth colors determined with a Beckman spectrophotometer were used. Color differences among 276 combinations of the 24 Bioform shade-guide colors were calculated with Eq. 1, with use of the Munsell notation, and also with the CIE L*a*b* equation for delta E. An estimate of the accuracy of Eq. 1 was 0.41 delta E units when delta E CIE was below 4.0. The Vita shade-guide colors were determined with a Beckman spectrophotometer. This data set contained 16 samples, and 120 combinations were used for calculation of color difference. An estimate of the accuracy for this set of data was 0.35 delta E units when delta E CIE was less than 4.0. The new color-difference equation provides a means for estimation of delta E CIE L*a*b* color difference between dental shades with Munsell notation. This equation will be useful for estimation of small delta E CIE L*a*b* values for shade-guide teeth that are designated in terms of Munsell notation. 相似文献
148.
Oral mucosal status and major salivary gland function 总被引:2,自引:0,他引:2
A Wolff P C Fox J A Ship J C Atkinson A A Macynski B J Baum 《Oral surgery, oral medicine, and oral pathology》1990,70(1):49-54
Normal salivary function is considered to be critical for the maintenance of healthy oral mucosa. However, few studies have examined mucosal changes in patients with objectively documented salivary gland performance. In the present report, the mucosal status of 298 subjects being evaluated in a dry mouth clinic was assessed. A complete oral examination was performed and unstimulated and stimulated salivary samples were collected separately from the parotid and submandibular/sublingual glands. Data were analyzed according to diagnosis and salivary output after the assignment of an oral mucosal rating to each subject. In general, the mucosal surfaces were well preserved and infections were not seen. Patients evaluated for Sj?gren's syndrome and radiation-induced xerostomia had the lowest salivary gland performance but displayed a mucosal status similar to denture-wearing healthy subjects or patients with normal salivary flow who had idiopathic xerostomia. However, those patients with a total lack of salivary flow rarely had normal-appearing oral mucosa. These results confirm a role for saliva in oral mucosal preservation and also suggest that other factors may act to maintain oral mucosal integrity. 相似文献
149.
150.
Dental abnormalities associated with familial expansile osteolysis: a clinical and radiographic study 总被引:1,自引:0,他引:1
C A Mitchell J G Kennedy R G Wallace 《Oral surgery, oral medicine, and oral pathology》1990,70(3):301-307
Familial expansile osteolysis is a rare and possibly unique form of hereditary bone dysplasia with dental manifestations that has affected 42 members of a Northern Ireland family for five generations. Twenty-seven family members, aged 3 to 60 years, were examined clinically and radiographically, and it was found that cervical and/or apical root resorption is an early manifestation of the dysplasia. Of the 20 family members with skeletal manifestations of familial expansile osteolysis, 16 showed root resorption. Root resorption may therefore be a good prognosticator for later bone involvement. 相似文献