全文获取类型
收费全文 | 22246篇 |
免费 | 2250篇 |
国内免费 | 653篇 |
专业分类
耳鼻咽喉 | 162篇 |
儿科学 | 592篇 |
妇产科学 | 317篇 |
基础医学 | 3269篇 |
口腔科学 | 398篇 |
临床医学 | 1592篇 |
内科学 | 4935篇 |
皮肤病学 | 394篇 |
神经病学 | 1657篇 |
特种医学 | 390篇 |
外国民族医学 | 4篇 |
外科学 | 2135篇 |
综合类 | 2590篇 |
现状与发展 | 5篇 |
一般理论 | 2篇 |
预防医学 | 1234篇 |
眼科学 | 229篇 |
药学 | 2747篇 |
2篇 | |
中国医学 | 654篇 |
肿瘤学 | 1841篇 |
出版年
2024年 | 48篇 |
2023年 | 576篇 |
2022年 | 1261篇 |
2021年 | 1143篇 |
2020年 | 951篇 |
2019年 | 1276篇 |
2018年 | 1146篇 |
2017年 | 1062篇 |
2016年 | 914篇 |
2015年 | 1004篇 |
2014年 | 1470篇 |
2013年 | 1337篇 |
2012年 | 1315篇 |
2011年 | 1494篇 |
2010年 | 1341篇 |
2009年 | 1061篇 |
2008年 | 1030篇 |
2007年 | 859篇 |
2006年 | 683篇 |
2005年 | 654篇 |
2004年 | 612篇 |
2003年 | 440篇 |
2002年 | 323篇 |
2001年 | 281篇 |
2000年 | 328篇 |
1999年 | 268篇 |
1998年 | 199篇 |
1997年 | 159篇 |
1996年 | 155篇 |
1995年 | 129篇 |
1994年 | 90篇 |
1993年 | 89篇 |
1992年 | 71篇 |
1991年 | 76篇 |
1990年 | 62篇 |
1989年 | 54篇 |
1988年 | 45篇 |
1987年 | 39篇 |
1985年 | 123篇 |
1984年 | 126篇 |
1983年 | 112篇 |
1982年 | 120篇 |
1981年 | 105篇 |
1980年 | 87篇 |
1979年 | 110篇 |
1978年 | 64篇 |
1977年 | 53篇 |
1976年 | 44篇 |
1975年 | 40篇 |
1973年 | 34篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
目的研究新发现的人内源性逆转录病毒 NP9基因在系统性红斑狼疮(systemic lupus erythematosus, SLE)患者体内表达及其蛋白功能预测.方法逆转录PCR、T-A克隆技术和DNA序列测定分离、克隆和分析 NP9基因, 检测40例SLE患者和48名正常对照的 NP9基因表达, 借助NCBI BLAST系列分析工具及相应的基因分析软件预测其蛋白功能.结果 SLE患者组逆转录病毒 NP9基因表达阳性率为77.5%(31/40),明显高于正常对照的8.3%(4/48), P<0.01. NP9基因编码产物由74个氨基酸组成,含有多个细胞核内分布信号,其等电点(pI)为9.59,与SLE患者体内高表达的某些细胞因子具有较高同源性.结论 SLE患者存在逆转录病毒 NP9基因特异性转录, NP9表达可能与SLE发生发展相关. 相似文献
82.
83.
Expression of MMP2, MMP9 and MMP3 in Breast Cancer Brain Metastasis in a Rat Model 总被引:11,自引:0,他引:11
In order to study the expression of MMP2, MMP3 and MMP9 in breast cancer brain metastasis, we used a syngeneic rat model of
distant metastasis of ENU1564, a carcinogen-induced mammary adenocarcinoma cell line. At six weeks post inoculation we observed
development of micro-metastasis in the brain. Immunohistochemistry and Western Blotting analyses showed that MMP-2, -3 and
-9 proteins expressions are consistently significantly higher in neoplastic brain tissue compared to normal brain tissue.
These results were confirmed by RT-PCR. In situ zymography revealed gelatinase activity within the brain metastasis. Gel zymography showed increase in MMP2 and MMP3 activity
in brain metastasis. Furthermore, we were able to significantly decrease the development of breast cancer brain metastasis
in animals by treatment with PD 166793, a selective synthetic MMP inhibitor. In addition, PD 166793 decreased the in vitro invasive cell behavior of ENU1546. Together our results suggest that MMP-2, -3 and -9 may be involved in the process of metastasis
of breast cancer to the brain. 相似文献
84.
85.
We investigated the oxygen uptake (O2) response to exhaustive square wave exercise of approximately 2, 5 and 8 min duration in cycling and running. Nine males completed a ramp test and three square wave tests on a motorised treadmill and the same four tests on a cycle ergometer, throughout which gas exchange was assessed (Douglas bag method). The peak O2 from the ramp test was higher for running than for cycling [mean (SD): 58.4 (2.8) vs. 55.9 (3.7) ml.kg–1.min–1; P=0.04]. However O2max (defined as the highest O2 achieved in any of the four tests) did not differ between running and cycling [60.0 (2.9) vs. 58.5 (3.3) ml.kg–1.min–1; P=0.15]. The peak O2 was similar (P>0.1) for the 5 and 8 min square wave tests [98.5 (1.8) and 99.2 (2.3) %O2max for running; 97.0 (4.2) and 97.5 (2.0) %O2max for cycling] but lower (P<0.001) for the 2-min test [91.8 (2.5) and 89.9 (5.5) %O2max for running and cycling respectively]. O2 increased over the final two 30-s collection periods of the 2-min test for cycling [O2=0.18 (0.15) l.min–1; P<0.01] but not running [O2=0.00 (0.09) l.min–1; P=0.98]. We conclude that in the aerobically fit the peak O2 for square wave running or cycling at an intensity severe enough to result in exhaustion in approximately 2 min is below O2max. In running, O2 plateaus at this sub-maximal rate. 相似文献
86.
87.
Hoshino Y Honma S Jones RW Ross J Santos N Gentsch JR Kapikian AZ Hesse RA 《Virology》2005,332(1):177-188
Of five globally important VP7 (G) serotypes (G1-4 and 9) of group A rotaviruses (the single most important etiologic agents of infantile diarrhea worldwide), G9 continues to attract considerable attention because of its unique natural history. Serotype G9 rotavirus was isolated from a child with diarrhea first in the United States in 1983 and subsequently in Japan in 1985. Curiously, soon after their detection, G9 rotaviruses were not detected for about a decade in both countries and then reemerged in both countries in the mid-1990s. Unexpectedly, however, such reemerged G9 strains were distinct genetically and molecularly from those isolated in the 1980s. Thus, the origin of the reemerged G9 viruses remains an enigma. Sequence analysis has demonstrated that the G9 rotavirus VP7 gene belongs to one of at least three phylogenetic lineages: lineage 1 (strains isolated in the 1980s in the United States and Japan), lineage 2 (strains first isolated in 1986 and exclusively in India thus far), and lineage 3 (strains that emerged/reemerged in the mid-1990s). Currently, lineage 3 G9 viruses are the most frequently detected G9 strains globally. We characterized a porcine rotavirus (A2 strain) isolated in the United States that was known to belong to the P[7] genotype but had not been serotyped by neutralization. The A2 strain was found to bear serotype G9 and P9 specificities as well as NSP4 [B] and subgroup I characteristics. By VP7-specific neutralization, the porcine G9 strain was more closely related to lineage 3 viruses than to lineage 1 or 2 viruses. Furthermore, by sequence analysis, the A2 VP7 was shown to belong to lineage 3 G9. These findings raise intriguing questions regarding possible explanations for the emergence of variations among the G9 strains. 相似文献
88.
89.
JOSTARNDT-F
GEN PUNTSCHART HOPPELER BILLETER 《Acta physiologica (Oxford, England)》1998,164(3):299-308
The fibre-type specific expression patterns of fast and slow isoforms of essential (alkali) myosin light chains (ELC) was analysed in trained, untrained and pathological human muscles. Biopsies from m. vastus lateralis of moderately trained and untrained persons, as well as highly trained endurance and strength athletes were analysed, by in situ hybridization, for the expression of the `fast' ELC 1f/3f and the `slow' ELC 1sb. We wanted to investigate if changes in the fibre-type specific ELC mRNA pattern could be used as markers for training adaptation, especially, if the mRNA of the slow ELC 1sb isoform would appear in type IIA fibres as a result of endurance training (Baumann et al. 1987). We found the fast/slow ELC expression patterns in the fibre types to be remarkably stable. Physiological stress, even high training loads, did not affect it. No IIA fibres expressing ELC 1sb mRNA were found. They could be detected, however, in pathological muscle samples, where fast/slow ELC patterns not found in normal muscles were frequent. Our data suggest that in healthy muscles, only a subset of the theoretically possible combinations of myosin heavy and light chain isoforms are expressed at the level of their mRNAs. 相似文献
90.
G. BERGSTR
M J. RUDENSTAM B. FOLKOW G. KARLSTR
M G. G
THBERG 《Acta physiologica (Oxford, England)》1992,146(4):527-528