全文获取类型
收费全文 | 13075篇 |
免费 | 529篇 |
国内免费 | 64篇 |
专业分类
耳鼻咽喉 | 75篇 |
儿科学 | 238篇 |
妇产科学 | 119篇 |
基础医学 | 1693篇 |
口腔科学 | 400篇 |
临床医学 | 731篇 |
内科学 | 3154篇 |
皮肤病学 | 290篇 |
神经病学 | 1097篇 |
特种医学 | 449篇 |
外科学 | 2581篇 |
综合类 | 31篇 |
一般理论 | 1篇 |
预防医学 | 330篇 |
眼科学 | 105篇 |
药学 | 869篇 |
中国医学 | 25篇 |
肿瘤学 | 1480篇 |
出版年
2023年 | 56篇 |
2022年 | 102篇 |
2021年 | 183篇 |
2020年 | 87篇 |
2019年 | 120篇 |
2018年 | 179篇 |
2017年 | 139篇 |
2016年 | 200篇 |
2015年 | 216篇 |
2014年 | 270篇 |
2013年 | 345篇 |
2012年 | 591篇 |
2011年 | 654篇 |
2010年 | 368篇 |
2009年 | 323篇 |
2008年 | 635篇 |
2007年 | 739篇 |
2006年 | 725篇 |
2005年 | 783篇 |
2004年 | 779篇 |
2003年 | 779篇 |
2002年 | 704篇 |
2001年 | 319篇 |
2000年 | 296篇 |
1999年 | 340篇 |
1998年 | 211篇 |
1997年 | 189篇 |
1996年 | 190篇 |
1995年 | 169篇 |
1994年 | 182篇 |
1993年 | 135篇 |
1992年 | 240篇 |
1991年 | 246篇 |
1990年 | 204篇 |
1989年 | 219篇 |
1988年 | 232篇 |
1987年 | 205篇 |
1986年 | 157篇 |
1985年 | 166篇 |
1984年 | 113篇 |
1983年 | 82篇 |
1982年 | 64篇 |
1981年 | 57篇 |
1980年 | 62篇 |
1979年 | 62篇 |
1978年 | 57篇 |
1977年 | 39篇 |
1976年 | 53篇 |
1975年 | 38篇 |
1969年 | 38篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
We evaluated the effects of rowing on the morphology and function of the leg extensor muscle in old people. The area and
the power of the leg extensor muscle were measured in 15 oarsmen – age [mean (SD)] 65 (3) years; height 171 (4) cm, body mass
68 (6) kg – and in 15 sedentary men – age 66 (4) years, height 170 (4) cm, body mass 67 (7) kg – who were matched on the basis
of their body size. The leg extensor muscle area of the oarsmen was larger than that of the sedentary men [77.8 (5.4) vs 68.4
(5.1) cm2, P<0.05]. Also the bilateral leg extension power of the oarsmen was larger than that of the sedentary men [1,624 (217) vs 1,296
(232) W, P<0.05]. Thus, the leg extension power per the leg extensor muscle area was not significantly different between two groups
[20.9 (2.0) vs 19.9 (2.1) W·cm–2) and leg extension power was correlated to the leg extensor muscle area (59–89 cm2, r=0.74, P<0.001). Also the 2,000-m rowing ergometer time of the oarsmen [495 (14) s; range 479–520 s] was related to leg extensor muscle
area (68–89 cm2, r=0.63, P<0.01). The results suggest that rowing prevents age-related muscle wasting and weakness.
Electronic Publication 相似文献
102.
In the present study, 13 cases of a peculiar gall-bladder granuloma characterized by marked proliferation of ceroid-fllled brown histiocytes were pathomorphologically, histochemically and ultrastructurally examined to define the pathologic features of such a lesion previously undescribed in the literature. The lesion grossly showed a granulomatous appearance of yellow brown to dark brown color developing in the wall of gall-bladder. Histologically, there was proliferation of histiocytes containing abundant brown pigment granules In their cytoplasm. The pigment granules proved to have staining characteristics closely resembling those of lipogenic ceroid-like pigment. Ultrastructurally, these granules showed membrane-bound, pleomorphic osmiophilic inclusions of heterogenous materials. With regard to the pathogenesis of this granuloma, it may be suggested that lipid components of bile juice, particularly unsaturated fatty acids and phospholipids, play an Important role as a source of ceroidogenesis In the proliferating histiocytes. 相似文献
103.
104.
Pituitary adenylate cyclase-activating polypeptide inhibits transforming growth factor-beta1-induced apoptosis in a human pituitary adenoma cell line 下载免费PDF全文
Oka H Jin L Kulig E Scheithauer BW Lloyd RV 《The American journal of pathology》1999,155(6):1893-1900
Pituitary adenylate cyclase-activating polypeptide (PACAP) was originally isolated from hypothalamic tissues based on its ability to stimulate cAMP production in cultured anterior pituitary cells. Recent studies have suggested a functional role for PACAP in the apoptosis of brain cells. However, the role of PACAP in regulating apoptosis in human pituitary adenomas has not previously been examined. Analysis of the cultured human pituitary adenoma cell line HP75, which expresses all three major PACAP receptors, showed that both PACAP-38 and PACAP-27 inhibited TGF-beta1-induced apoptosis. Treatment with the PACAP receptor antagonists PACAP 6-38 (PACAP type I receptor antagonist) and (p-chloro-D-Phe(6), Leu(17))-VIP (PACAP type II receptor antagonist) blocked the effects of PACAP-38 on the inhibition of transforming growth factor-beta1 (TGF-beta1)-induced apoptosis, confirming the specificity of the role of PACAP. Treatment with forskolin but not phorbol 12-myristate 13-acetate (PMA) also inhibited TGF-beta1-induced apoptosis. TGF-beta1 treatment was associated with an increase in mitogen-activated protein kinase (MAP kinase) when analyzed by Western blotting, but PACAP inhibition of TGF-beta1-induced apoptosis was not associated with activation of MAP kinase. Immunocytochemical analysis of the cell cycle cyclin-dependent kinase inhibitor p27 showed that treatment with TGF-beta1, forskolin, PMA, and PACAP increased p27 expression in cultured HP75 cells. These results indicate that PACAP is a highly specific inhibitor of TGF-beta1-induced apoptosis in the HP75 human pituitary adenoma cell line and that PACAP, TGF-beta1, forskolin, and PMA all stimulate expression of the TGF-beta-regulated cell cycle protein p27 in the HP75 human pituitary adenoma cell line. The HP75 cell line can be used as a model to study the regulation of apoptosis in human pituitary cells. 相似文献
105.
CD10 is a cell surface metalloprotease expressed by a variety of normal cell types, including lymphoid precursor cells, germinal center B lymphocytes, and some epithelial cells. We noticed that stromal cells of some cancers are positive for CD10. In this study, we investigated the role of CD10 produced by the stromal cells of colorectal neoplasms in the progression of colorectal neoplasms. Immunohistochemical examination of CD10 and p53 was performed in 169 colorectal epithelial neoplasms representing various stages of carcinogenesis. The results were correlated with the morphologic characteristics of the neoplasms. There was no expression of CD10 in the stromal cells of normal colorectal tissue. CD10-positive stromal cells were present adjacent to the tumor cells in 16 of 73 adenomas with mild or moderate dysplasia. More frequent expression of CD10 by the stromal cells was detected in adenomas with severe dysplasia (12 of 17), intramucosal carcinomas (10 of 16), and invasive carcinomas (50 of 63) than in adenomas with mild or moderate dysplasia (P < 0.0001). Expression of CD10 by > 10% of the stromal cells was detected only within the area of the invasive growth front of invasive carcinomas, not in adenomas and in only 1 of the intramucosal carcinomas. The difference between invasive and non invasive tumors was significant (P < 0.0001). The stromal expression of CD10 was significantly associated with the accumulation of p53 and a larger tumor size. These results indicate that CD10 expression is an integral part of colorectal carcinogenesis. CD10 expression seems to contribute to the invasion and thus probably facilitates metastasis. 相似文献
106.
Functional mapping of the activity of the R region in the human T-cell leukemia virus type I long terminal repeat to increase gene expression 总被引:3,自引:0,他引:3
We previously demonstrated the activity of the R fragment in the long terminal repeat of human T-cell leukemia virus type I for elevation of the level of gene expression. In this study, the fragment was deleted with BAL31 nuclease to determine its functional domain. Series of the shortened R fragments were linked to the simian virus 40 promoter unit, which regulated expression of a reporter gene. Examination with the R fragments deleted from the 5 and 3 ends showed that borders of the functional domain were mapped within nucleotide positions 458 to 473 for the 5 end and nucleotide positions 559 to 594 for the 3 end, respectively. Thus we conclude that a 136-base-pair fragment corresponding to the second half of the R region was sufficient to allow elevation of the level of gene expression. 相似文献
107.
A medaka gene map: the trace of ancestral vertebrate proto-chromosomes revealed by comparative gene mapping 总被引:16,自引:0,他引:16 下载免费PDF全文
The mapping of Hox clusters and many duplicated genes in zebrafish indicated an extra whole-genome duplication in ray-fined fish. However, to reconstruct the preduplication chromosomes (proto-chromosomes), the comparative genomic studies of more distantly related teleosts are essential. Medaka and zebrafish are ideal for this purpose, because their lineages separated from their last common ancestor approximately 140 million years ago. To reconstruct ancient vertebrate chromosomes, including the chromosomes of the vertebrate ancestor of humans from 450 million years ago, we mapped 818 genes and expressed sequence tags (ESTs) on a single meiotic backcross panel obtained from inbred strains of the medaka, Oryzias latipes. Comparisons of linkage relationships of orthologous genes among three species of vertebrates (medaka, zebrafish, and human) indicate the number and content of the chromosomes of the last common ancestor of ray-fined fish and lobe-fined fish (including humans), and the extra whole genome duplication event in the ray-fin lineage occurred in the common ancestor of perhaps all teleosts. 相似文献
108.
Emiko Ono Yuji Maeda Hidenori Tanimoto Yuma Fukutomi Chiyako Oshikata Kiyoshi Sekiya Takahiro Tuburai Naomi Turikisawa Mamoru Otomo Masami Taniguchi Houta Ishii Akihiko Asahina Eishi Miyazaki Tosihide Kumamoto Kazuo Akiyama 《Arerugī》2007,56(6):587-592
BACKGROUND: Recently, it is recognized that the patients of oral allergy syndrome (OAS) to fruits are increasing. However, there are little knowledges of the background, character, and seriousness about these patients in Kanto regions. OBJECTIVE: We aimed to investigate the clinical features of OAS patients to plant origin foods in Kanto regions. METHODS: The patient, who visited Sagamihara National Hospital from 2000 to 2005 and developed some allergic symptoms to plant origin foods, were studied by a questionary survey. RESULTS: As for the 42 subjects, average age are 36 years old, male:female=8:34, merger of other allergic disease is 35 allergic rhinitis of 42 subjects (83%), 34 of asthma (81%), 14 of atopic dermatitis (33%). The causes of OAS symptoms are 32 rose-family fruits, 34 non-rose family fruits, 14 vegetables, 11 nuts, 2 grains subjects. As for the symptom, only in the oral and pharynx symptoms are found in 12, the systemic symptoms is 29, anaphylaxis is 11 subjects. Allergic rhinitis preceded on the 90% subjects with pollinosis, very high rate. On the other hand, the 20% of all subjects have no symptoms of allergic rhinitis. CONCLUSION: A nasal catarrh symptoms went ahead in most of the OAS subjects in Kanto regions. In addition, considering from some patients have no black alder pollinosis and/or are allergic to many non-rose-family fruits at high frequency, there might be a broad cross-reactivity between many pollens other than alder and plant origin foods. 相似文献
109.
110.
Inhibition of in vivo tumorigenicity and invasiveness of a human glioblastoma cell line transfected with antisense uPAR vectors 总被引:1,自引:0,他引:1
Yoshinori Go Shravan K. Chintala Sanjeeva Mohanam Ziya Gokaslan Boyapati Venkaiah Rolf Bjerkvig Kazunari Oka Garth L. Nicolson Raymond Sawaya Jasti S. Rao 《Clinical & experimental metastasis》1997,15(4):440-446
Our previous studies showed that glioblastomas express increased urokinase-type plasminogen activator receptors (uPARs) in comparison to low-grade gliomas (Yamamoto et al., Cancer Res., 54, 5016-5020, 1994). To explore whether downregulation of uPAR inhibits tumor formation and invasiveness, a human glioblastoma cell line was transfected with a cDNA construct corresponding to 300 bp of the human uPAR's 5¢ end in an antisense orientation, resulting in a reduced number of uPA receptors. Co-culture studies with tumor spheroids and fetal rat brain aggregates showed that antisense SNB19-AS1 cells expressing reduced uPAR failed to invade fetal rat brain aggregates. Intracerebral injection of SNB19-AS1 stable transfectants failed to form tumors and were negative for uPAR expression in nude mice. Thus uPAR appears in this model to be essential for tumorigenicity and invasion of glioblastomas in vivo. 相似文献