全文获取类型
收费全文 | 164003篇 |
免费 | 15697篇 |
国内免费 | 10267篇 |
专业分类
耳鼻咽喉 | 1241篇 |
儿科学 | 1988篇 |
妇产科学 | 1834篇 |
基础医学 | 24024篇 |
口腔科学 | 2733篇 |
临床医学 | 20154篇 |
内科学 | 22920篇 |
皮肤病学 | 1756篇 |
神经病学 | 8154篇 |
特种医学 | 5721篇 |
外国民族医学 | 76篇 |
外科学 | 15637篇 |
综合类 | 26857篇 |
现状与发展 | 34篇 |
一般理论 | 13篇 |
预防医学 | 11487篇 |
眼科学 | 4073篇 |
药学 | 18887篇 |
152篇 | |
中国医学 | 9272篇 |
肿瘤学 | 12954篇 |
出版年
2024年 | 636篇 |
2023年 | 2585篇 |
2022年 | 6601篇 |
2021年 | 8328篇 |
2020年 | 6179篇 |
2019年 | 5423篇 |
2018年 | 5657篇 |
2017年 | 5243篇 |
2016年 | 4997篇 |
2015年 | 7276篇 |
2014年 | 9051篇 |
2013年 | 8623篇 |
2012年 | 12078篇 |
2011年 | 13040篇 |
2010年 | 8997篇 |
2009年 | 7303篇 |
2008年 | 8788篇 |
2007年 | 8758篇 |
2006年 | 8069篇 |
2005年 | 7412篇 |
2004年 | 5627篇 |
2003年 | 5473篇 |
2002年 | 4655篇 |
2001年 | 3887篇 |
2000年 | 3428篇 |
1999年 | 3110篇 |
1998年 | 1949篇 |
1997年 | 2093篇 |
1996年 | 1481篇 |
1995年 | 1426篇 |
1994年 | 1278篇 |
1993年 | 878篇 |
1992年 | 1094篇 |
1991年 | 973篇 |
1990年 | 882篇 |
1989年 | 802篇 |
1988年 | 718篇 |
1987年 | 628篇 |
1986年 | 581篇 |
1985年 | 449篇 |
1984年 | 377篇 |
1983年 | 310篇 |
1982年 | 275篇 |
1981年 | 234篇 |
1980年 | 198篇 |
1979年 | 203篇 |
1978年 | 192篇 |
1977年 | 211篇 |
1976年 | 191篇 |
1974年 | 156篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Previous studies have demonstrated variability in the phenotype of rat C6 glioma cells. In the present study, we compared morphology, growth rate, and beta-adrenergic regulation of gene expression in early (P39-47) and late (P55-90) passage C6 cells. Morphological changes were observed in five independently derived, late passage populations. In four of the five, the untreated cells were more polygonal than the fibroblast-like parental cells, and only a small fraction exhibited process outgrowth after dbcAMP treatment. Untreated cells from the fifth late passage population had longer cytoplasmic processes than parental cells and responded to dbcAMP with further process outgrowth. All late passage populations had shorter generation times than the parental cells. In early passage cells, treatment with the beta-adrenergic agonist, isoproterenol (IPR), resulted in an increase in c-fos mRNA and a decrease in c-jun mRNA (Gu-bits RM, Yu H: J Neurosci Res, 30:625-630, 1991). Both of these immediate early gene responses were irreversibly lost between P50 and P55. Additional differences in basal or IPR-induced mRNA levels were observed for beta-APP, GFAP, NGF, and PPE, but not for a number of other mRNAs. These results are discussed in relationship to previously described differences in the ability of early and late passage C6 cells to accumulate cAMP (Mallorga P, et al.: Biochim Biophys Acta 678:221-229, 1981). 相似文献
93.
E C Azmitia I Yu H M Akbari N Kheck P M Whitaker-Azmitia D R Marshak 《Journal of chemical neuroanatomy》1992,5(4):289-298
The availability of the primary amino acid sequence for a large number of molecules provides a fruitful opportunity for their cellular localization by utilizing the procedure of antipeptide antibody formation. This procedure permits a synthetic peptide sequence to be attached to a carrier molecule for the purpose of inoculating an animal to raise specific antibodies against the selected protein sequence. In this report we describe a number of steps that can be taken to increase the likelihood that the selected peptide sequence will be specific and antigenic. In addition, we describe how the peptides are synthesized, purified and coupled to keyhold limpet hemocyanin. The preparation of the antibody and its characterization are also presented in this method report. The immunocytochemical staining at both the light and ultrastructural level with serotonin (5-HT1A) receptor antipeptide antibodies is discussed. The advantages and disadvantages of this procedure are summarized. 相似文献
94.
95.
E. V. Borisova D. Yu. Rusakov S. K. Sudakov 《Bulletin of experimental biology and medicine》1992,114(3):1328-1332
96.
97.
98.
Patrick Callaghan RN BSc MSc Cheung Siu Shan RN BN Lau Suk Yu RN BN Lo Wai Ching RN BN Tsui Lai Kwan RN BN 《Journal of advanced nursing》1997,26(1):33-40
This study investigated whether previous contact with mental illness affected the attitudes to mental illness (AMI) of general student nurses in Hong Kong — the contact hypothesis. We employed a quasi-experimental design. We compared the attitudes to mental illness of students who had previous contact with mental illness through having taken a psychiatric secondment with those who had not taken a psychiatric secondment. Also, we compared the AMI of: students who had taken other courses related to mental illness with those who had not; those who had a family history of mental illness with those who had not; and those who lived with a mentally ill relative with those who did not. We found that previous contact with mental illness had no significant effect on the attitudes to mental illness of the students. In other words our findings do not support the contact hypothesis. Our sample expressed positive general attitudes to mental illness when presented with general issues about mental illness. However, their attitudes were less positive when presented with specific issues about mental illness that might impinge upon their daily lives. We discuss the implications of these findings for mental health nursing practice, education and research. 相似文献
99.
J E Gervasoni R N Taub M T Yu D Warburton M Sabbath S Gilleran D L Coppock J D'Alessandri S Krishna M Rosado 《Cancer research》1992,52(19):5244-5249
Anthracycline-resistant HL-60/AR cells and their drug-sensitive HL-60/S counterparts were characterized by karyotypic analysis and examined for the overexpression of DNA and mRNA sequences coding for P-glycoprotein (Pgp). The HL-60/S cells were karyotypically stable over a 5-year period of study (1986-1991), except for an additional small Giemsa-positive band noted at 7q22 in cultures harvested in 1987, but not in 1986. This change did not affect drug sensitivity. The drug-resistant HL-60/AR cells examined in 1986, 1987, and 1991 demonstrated a very stable karyotype. The most striking feature was a large homogeneously staining region in the long arm of chromosome 7 (7q11.2), and translocation of the remainder of the long arm to another centromere. Other changes in the HL-60/AR cells included inversion in 9q, partial deletion of the short arm of chromosome 10p, addition of material to the p arm of der(16), loss of chromosome 22, and the appearance of a new marker chromosome. Both HL-60/S and the HL-60/AR cells were found not to amplify DNA or mRNA sequences coding for the Pgp. Thus, although the HL-60/AR cells possess the classical multidrug resistance phenotype and demonstrate a homogeneously staining region near the region of the MDR1 gene, their resistance is due to mechanisms other than those coded for by MDR1. 相似文献
100.
在崇尚医学美学的今天,手术室护理人员通过数届"护理审美"活动的研讨,我院神经外科专科组成员针对放置体位规范化的要求和对美学的理解,敢于在日常护理工作中发现问题,探究原因,自行设计新式约束带,改进以往在放置神经外科侧卧位时,约束病人的不规范,以及约束病人肢体时重复劳动的烦琐,给临床护理工作带来了便捷. 相似文献