全文获取类型
收费全文 | 46530篇 |
免费 | 4972篇 |
国内免费 | 1261篇 |
专业分类
耳鼻咽喉 | 233篇 |
儿科学 | 1131篇 |
妇产科学 | 365篇 |
基础医学 | 15788篇 |
口腔科学 | 561篇 |
临床医学 | 3334篇 |
内科学 | 7801篇 |
皮肤病学 | 1326篇 |
神经病学 | 1673篇 |
特种医学 | 2503篇 |
外国民族医学 | 10篇 |
外科学 | 2971篇 |
综合类 | 5265篇 |
现状与发展 | 14篇 |
预防医学 | 1904篇 |
眼科学 | 332篇 |
药学 | 2836篇 |
9篇 | |
中国医学 | 1294篇 |
肿瘤学 | 3413篇 |
出版年
2024年 | 70篇 |
2023年 | 631篇 |
2022年 | 1129篇 |
2021年 | 1687篇 |
2020年 | 1508篇 |
2019年 | 1758篇 |
2018年 | 1869篇 |
2017年 | 1716篇 |
2016年 | 1647篇 |
2015年 | 1829篇 |
2014年 | 2636篇 |
2013年 | 3132篇 |
2012年 | 2414篇 |
2011年 | 2752篇 |
2010年 | 2233篇 |
2009年 | 2054篇 |
2008年 | 2121篇 |
2007年 | 2043篇 |
2006年 | 1884篇 |
2005年 | 1633篇 |
2004年 | 1614篇 |
2003年 | 1438篇 |
2002年 | 1154篇 |
2001年 | 1069篇 |
2000年 | 917篇 |
1999年 | 846篇 |
1998年 | 885篇 |
1997年 | 807篇 |
1996年 | 748篇 |
1995年 | 755篇 |
1994年 | 745篇 |
1993年 | 665篇 |
1992年 | 421篇 |
1991年 | 338篇 |
1990年 | 365篇 |
1989年 | 297篇 |
1988年 | 220篇 |
1987年 | 173篇 |
1986年 | 160篇 |
1985年 | 349篇 |
1984年 | 383篇 |
1983年 | 240篇 |
1982年 | 302篇 |
1981年 | 234篇 |
1980年 | 184篇 |
1979年 | 174篇 |
1978年 | 120篇 |
1977年 | 102篇 |
1976年 | 131篇 |
1975年 | 74篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
121.
TSG-6基因在3T3-L1脂肪细胞诱导分化中表达水平的变化 总被引:2,自引:0,他引:2
[目的] 探讨TSG-6基因在3T3-L1脂肪细胞诱导分化中表达水平的变化。[方法] 采用细胞培养和RT-PCR技术,检测细胞诱导分化不同时段脂肪细胞中TSG-6基因的表达水平。[结果] ①随着脂肪细胞逐渐分化成熟,TSG-6基因mRNA表达水平逐渐升高;②TSG-6基因表达水平除在细胞分化第0-2d、第3-5d和第7-10d各时段内差异无显著性(P>0.05)外,其余各时段之间表达水平差异均有显著性(P<0.05)。[结论] TSG-6基因与细胞分化以及脂原形成可能相关。 相似文献
122.
肌钙蛋白T在诊断急性心肌梗死中的应用 总被引:2,自引:0,他引:2
采用肌钙蛋白T半定量试纸条检测急性心肌梗死16例,心绞痛13例,以20例健康体检者为对照组。结果显示,AMI组阳性反应15例,心绞组仅1例阳性,对照组均为阴性,结果提示,TnT半定量试纸条检测法在AMI诊断中,敏感性和特异性较高,方法简便方便,尤其适用于急诊室,内科监护病房及基层医院使用。 相似文献
123.
Rolf Gronas B. Eng Peter G. Kalman MD Daryl S. Kucey MD Graham A. Wright PhD 《Journal of magnetic resonance imaging : JMRI》1997,7(4):637-643
Flow-independent angiography (FIA), an approach that isolates arterial blood using MR relaxation characteristics rather than flow effects, was evaluated for application in peripheral vascular disease (PVD). First, pilot studies were conducted in which FIA coronal projection images were obtained from controls and symptomatic patients with PVD to assess clinical utility. All control images corresponded to the expected leg arterial anatomy with little interference from deep veins (one of five) and muscle (zero of five). Superficial venous signal was less well suppressed in comparison to deep veins (four of five). Images of symptomatic patients were less consistent with difficulty suppressing muscle and deep venous signal in some cases and edema when present. We then compared T2 values for muscle (T2m, tibialis anterior), arterial blood (femoral and popliteal arteries), and venous blood (femoral, popliteal, and saphenous veins) in controls (n = 8) and symptomatic patients with intermittent claudication (n = 5) or ischemic rest pain (n = 7). Changes in T2 measurements of various tissues accounted for poorer contrast in symptomatic patients. Patients with ischemic rest pain had significantly higher T2m compared with controls (T2m = 39.3 ± 2.1 (1 standard error of the mean [SEM]) versus 30.9 ± .4, P < .01). For all measurements, other than saphenous vein, variances were greater in symptomatic patients. To realize the inherent advantages of FIA for this clinical application, additional work on suppression of signals from muscle, veins, and edema is required. One promising approach involves shifting from projection images to three-dimensional acquisitions for improved tissue suppression. 相似文献
124.
黄芪注射液对严重创伤患者的免疫调节 总被引:1,自引:0,他引:1
目的 探讨黄芪注射液对严重创伤患者的免疫调节作用。方法 选择 5 0例严重创伤患者 (ISS ,创伤严重度评分≥16 ) ,检测应用黄芪注射液 ( 4 0ml)前后T淋巴细胞亚群血清IL 2及可溶性白介素 2受体 (SIL 2R)。结果 严重创伤患者伤后IL 2、CD4 +和CD4 +/CD8+减低 ,而SIL 2R和CD8+升高 ,黄芪治疗组在伤后 14d血中IL 2、T淋巴细胞CD4 +亚群、CD4 +/CD8+降低及SIL 2R、CD8+升高程度均低于治疗前 ,P <0 .0 5。结论 严重创伤患者伤后细胞免疫功能明显抑制 ,应用黄芪注射液可以增加机体免疫功能 相似文献
125.
本文应用磁性磷酸酶-抗碱性磷酸酶桥联酶标技术(APAAP),对27例原发性肾小球疾病患者外周血T淋巴细胞亚群进行观察。结果表明:本组病例表现为CD细胞升高,CD细胞减少,和CD/CD比值增加。提示原发性肾小球疾病可导致细胞免疫功能改变,T淋巴细胞亚群的变化,是肾组织损害的一个间接证据,可作为临床诊断一个有价值的参考指标。 相似文献
126.
IgM allotype heterozygous F1 mice were independently suppressed for Igh6a or Igh6b to
evaluate the contribution of B-1 and B-2 cells to natural serum IgM levels and Ab responses.
B-2 B cells expressing IgM of the suppressed allotype were evident in the spleens of
suppressed mice 4 to 6 weeks after cessation of the suppression regimen, whereas B-1 B
cells of the suppressed allotype were undetectable for up to 9 months. Although serum IgM
of the suppressed allotype was initially depleted in mice suppressed for either allotype, by
7 months of age, there were detectable levels of IgM of the suppressed allotype in the
serum; however, the levels were significantly below that found in nonsuppressed mice.
When mice were immunized with either the T-independent or T-dependent form of
phosphorylcholine, those suppressed for either allotype, and consequently depleted of B-1
B cells of that allotype, did not respond with phosphorylcholine-specific IgM of the
suppressed allotype. In contrast, when mice were immunized with α1-3 dextran, the Igh6a
allotype-suppressed mice were able to produce dextran-specific IgM of that allotype. These
results show that allotype-bearing B-1 cells of both allotypes can be effectively suppressed
by this suppression protocol and this produces long-lasting effects on B-1 cell levels and
serum IgM of the suppressed allotype. These observations reflect the derivation of the
majority of B-1 cells from fetal-neonatal precursors, which cannot be replaced by newly
emerging B-2 cells of adult origin. Their ablation by antibody treatment results in
permanent alterations to the adult B-cell repertoire. 相似文献
127.
We investigated populations of the infiltrating cells in Bowen's disease (BD) and squamous cell carcinoma (SCC), both of which arose in the same patient, using the Avidin-Biotin-peroxidase complex method with eight monoclonal antibodies. T lymphocytes were most predominant among infiltrating cells; NK cells, B cells, and monocytes were rarely seen in either BD or SCC. Analysis of subsets of the infiltrating T lymphocytes revealed that the number of suppressor/cytotoxic (s/c) T cells was twice that of helper/inducer (h/i) T cells in BD, while the number of s/c T cells was lower than that of h/i T cells in SCC. The immunohistochemical results in the present case differed from those of predominant infiltration of h/i T cells and of s/c T cells in three other reports of BD and SCC. These results suggest that the population of the cellular infiltrates may be modulated by the nature of tumors and by the immuno-competent state of the hosts. 相似文献
128.
129.
130.
A panel of synthetic peptides representing human lymphocyte antigen (HLA) B8, other class I and class II restricted T cell epitopes and two B cell epitopes, were all able to compete with recognition of a HLA B8 restricted epitope by a cytotoxic T cell clone. Competition was obtained when the competitor peptides were added either before or after the target epitope. The target epitope also had a slow off rate, implicating allosteric inhibition. The presence of non-specific, allosteric binding sites may interfere with experiments attempting to define immunologically relevant MHC binding specificities. 相似文献