全文获取类型
收费全文 | 14983篇 |
免费 | 1505篇 |
国内免费 | 44篇 |
专业分类
耳鼻咽喉 | 192篇 |
儿科学 | 333篇 |
妇产科学 | 271篇 |
基础医学 | 1684篇 |
口腔科学 | 274篇 |
临床医学 | 2618篇 |
内科学 | 3003篇 |
皮肤病学 | 208篇 |
神经病学 | 1344篇 |
特种医学 | 481篇 |
外科学 | 2149篇 |
综合类 | 151篇 |
一般理论 | 12篇 |
预防医学 | 1472篇 |
眼科学 | 317篇 |
药学 | 1013篇 |
中国医学 | 14篇 |
肿瘤学 | 996篇 |
出版年
2024年 | 20篇 |
2023年 | 224篇 |
2022年 | 143篇 |
2021年 | 349篇 |
2020年 | 369篇 |
2019年 | 294篇 |
2018年 | 510篇 |
2017年 | 381篇 |
2016年 | 421篇 |
2015年 | 448篇 |
2014年 | 653篇 |
2013年 | 869篇 |
2012年 | 1006篇 |
2011年 | 1041篇 |
2010年 | 730篇 |
2009年 | 782篇 |
2008年 | 965篇 |
2007年 | 973篇 |
2006年 | 1005篇 |
2005年 | 982篇 |
2004年 | 946篇 |
2003年 | 802篇 |
2002年 | 789篇 |
2001年 | 164篇 |
2000年 | 133篇 |
1999年 | 159篇 |
1998年 | 192篇 |
1997年 | 186篇 |
1996年 | 139篇 |
1995年 | 110篇 |
1994年 | 84篇 |
1993年 | 70篇 |
1992年 | 61篇 |
1991年 | 54篇 |
1990年 | 47篇 |
1989年 | 50篇 |
1988年 | 32篇 |
1987年 | 29篇 |
1986年 | 41篇 |
1985年 | 45篇 |
1984年 | 34篇 |
1983年 | 33篇 |
1982年 | 24篇 |
1981年 | 22篇 |
1980年 | 19篇 |
1978年 | 15篇 |
1977年 | 8篇 |
1976年 | 13篇 |
1975年 | 11篇 |
1949年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 21 毫秒
41.
Caroline S. Drugan rea Stone Steve M. Game Stephen S. Prime 《Journal of oral pathology & medicine》1997,26(7):327-333
This study examined the mitogenic response to keratinocyte growth factor (KGF) of normal and tumour-derived human oral keratinocytes in which the degree of cellular differentiation was known and in contiguous fibroblast cultures derived from the malignant epithelial cultures. Keratinocytes, but not fibroblasts, were stimulated by KGF. There by demonstrating epithelial target cell specificity of the ligand. KGF-induced stimulation of the tumour-derived keratinocytes cultured in the absence of the 3T3 fibroblast support broadly correlated with the degree of cellular differentiation; well-differentiated keratinocytes were stimulated more by KGF than their less differentiated counterparts. Malignant oral keratinocytes expressed KGF cell surface receptors (KD 451-709 pM; receptors/cell 2306-413645), but KGF receptor mRNA did not correlate with either KGF-induced mitogenesis or the degree of epithelial cell differentiation. When the tumour-derived keratinocytes were cultured in the presence of 3T3 fibroblasts, the mitogenic response to KGF was comparable to normal epithelial cells. The results suggest that KGF-mediated growth stimulation may not be significant in providing a selective advantage for the growth of malignant keratinocytes. 相似文献
42.
Reardon O. Olubayo Steve Mihok Eli Munyoki Leonard H. Otieno 《Parasitology research》1994,80(3):177-181
The pattern of infection inGlossina morsitans morsitans andG. m. centralis membrane-fed on eland, buffalo or goat blood mixed withTrypanosoma congolense orT. brucei was studied from day 1 to day 10. Tsetse were initially permissive vectors, with most flies harbouring infections of 104–105 parasites on day 3. However, after a second blood meal on day 3, flies cleared many infections withG. m. morsitans clearing more infections thanG. m. centralis. Infective feeds of goat blood consistently increased final infection rates by limiting the number of infections lost between days 3 and 6. In further experiments withG. m. morsitans only, this effect was replicated by feeding flies on erythrocytes but not on serum. These results suggest that compounds from some mammalian erythrocytes match the target specificity ofG. m. morsitans midgut lectins and, hence, have a protective effect on trypanosome establishment in the fly. 相似文献
43.
It is often useful in studies of intellectual disability to be able to stratify the sample in terms of intellectual level. However, this information is sometimes difficult to obtain, and can involve a great deal of time if full IQ assessments are performed. This study explores the accuracy with which IQ scores can be projected by multiple regression from adaptive behaviour scores provided by informants. Fifty-one people with moderate, severe or profound intellectual disability received IQ assessments using the Kaufman Assessment Battery, and adaptive behaviour assessments using the Adaptive Behavior Scales (ABS). Ninety percent of projected estimates differed by less than 30% from that estimated by the K-ABC. Mean percentage divergence between actual and predicted estimates of IQ for the 51 cases for which all data were available was 15.0%. Limitations of the technique are discussed. The actual coefficients for calculating IQ are given in tabular form. 相似文献
44.
Collagen breakdown products and lung collagen metabolism: an in vitro study on fibroblast cultures. 总被引:8,自引:0,他引:8
下载免费PDF全文
![点击此处可从《Thorax》网站下载免费的PDF全文](/ch/ext_images/free.gif)
BACKGROUND--In fibrotic diseases such as pulmonary fibrosis there is evidence suggesting enhanced synthesis and degradation of lung connective tissue components, including collagen. It has therefore been hypothesised that products of collagen degradation may have a role in the promotion of collagen deposition. In support of this hypothesis, it has recently been shown that intravenous injection of lung collagen degradation products in experimental animals stimulated collagen synthesis leading to increased collagen deposition and diffuse interstitial lung disease. METHODS--Rabbit and human fibroblast cultures from lung and skin were used as an in vitro model to study the responses of these cells to rabbit collagen degradation products. The effects of an acute exposure to collagen degradation products on synthesis of collagen and noncollagenous protein have been studied in confluent cultures by [3H]-proline incorporation. The effects of collagen degradation products on fibroblast proliferation and production of genetic types of collagen have also been investigated. RESULTS--The acute exposure of rabbit lung fibroblast cultures to collagen degradation products significantly increased collagen synthesis without affecting non-collagenous protein synthesis. This effect was dose related, specific for lung fibroblasts, and species specific. Collagen degradation products altered the rate of synthesis of genetic types of collagen with a consequent decrease of type III/I+III collagen ratio (0.26 (0.04) treated with collagen degradation products; 0.45 (0.02) controls). These effects occurred without the intervention of serum factors. In addition, collagen degradation products neither affected fibroblast proliferation nor selected specific clones emphasising one type of collagen. CONCLUSIONS--These results suggest that collagen degradation products can influence lung collagen metabolism by stimulating collagen synthesis. The regulation of collagen mass by collagen degradation products may be of importance in lung collagen homeostasis in vivo. 相似文献
45.
46.
47.
Steve Nelson CPA 《Administration and policy in mental health》1992,20(2):129-133
Some nonprofit mental health organizations are buying real estate in order to own service delivery sites and to provide housing for clients. Owning real estate generally requires long-term financing to conserve cash. This article explores tax exempt financing methods available to nonprofit mental health organizations. 相似文献
48.
49.
50.