全文获取类型
收费全文 | 14389篇 |
免费 | 638篇 |
国内免费 | 63篇 |
专业分类
耳鼻咽喉 | 215篇 |
儿科学 | 286篇 |
妇产科学 | 174篇 |
基础医学 | 2061篇 |
口腔科学 | 359篇 |
临床医学 | 841篇 |
内科学 | 4015篇 |
皮肤病学 | 200篇 |
神经病学 | 933篇 |
特种医学 | 538篇 |
外科学 | 2140篇 |
综合类 | 54篇 |
预防医学 | 366篇 |
眼科学 | 334篇 |
药学 | 1085篇 |
中国医学 | 31篇 |
肿瘤学 | 1458篇 |
出版年
2023年 | 72篇 |
2022年 | 126篇 |
2021年 | 213篇 |
2020年 | 146篇 |
2019年 | 200篇 |
2018年 | 203篇 |
2017年 | 161篇 |
2016年 | 246篇 |
2015年 | 230篇 |
2014年 | 332篇 |
2013年 | 439篇 |
2012年 | 702篇 |
2011年 | 770篇 |
2010年 | 445篇 |
2009年 | 368篇 |
2008年 | 752篇 |
2007年 | 804篇 |
2006年 | 851篇 |
2005年 | 880篇 |
2004年 | 817篇 |
2003年 | 774篇 |
2002年 | 763篇 |
2001年 | 383篇 |
2000年 | 365篇 |
1999年 | 332篇 |
1998年 | 244篇 |
1997年 | 171篇 |
1996年 | 160篇 |
1995年 | 127篇 |
1994年 | 117篇 |
1993年 | 113篇 |
1992年 | 248篇 |
1991年 | 219篇 |
1990年 | 217篇 |
1989年 | 208篇 |
1988年 | 194篇 |
1987年 | 184篇 |
1986年 | 149篇 |
1985年 | 136篇 |
1984年 | 120篇 |
1983年 | 88篇 |
1982年 | 67篇 |
1981年 | 71篇 |
1980年 | 63篇 |
1979年 | 90篇 |
1978年 | 72篇 |
1976年 | 55篇 |
1975年 | 51篇 |
1972年 | 57篇 |
1968年 | 60篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Shigeko Tanaka Minoru Yoshiyama Yukihiro Imanishi Koichi Nakahira Takashi Hanaki Yukari Naito Mizue Imai Masahiro Tanaka 《Magnetic resonance in medical sciences》2006,5(4):207-210
One diagnostic criterion for metabolic syndrome is obesity from the accumulation of visceral fat; others include abdominal circumference and area of visceral fat as measured by computed tomography (CT) at the umbilical level. We evaluated visceral fat using frequency-selective excitation magnetic resonance (MR) imaging SPAIR (spectral attenuation with inversion recovery) water suppression THRIVE (3D T1-high resolution isotropic volume examination). Fifty of 70 slices with 2-mm interval were used to render and measure volume of visceral fat ranging within 10 cm of the umbilicus; the area of visceral fat at the umbilical level was also measured. Imaging was completed using breath hold within 14 s. Image processing was easier than using CT. 相似文献
2.
3.
4.
5.
Mitsumasa Iwata Shunji Izuta Motoshi Suzuki Kiyohide Kojima Yoshihito Furuhashi Yutaka Tomoda Shonen Yoshida 《Cancer science》1991,82(4):433-439
We examined the mechanisms of the inhibition of DNA synthesis by a new platinum compound, (-)-( R )-2-aminomethylpyrrolidine(1,1-cyclobutane-dicarboxylato)-2-platinum(II) monohydrate (DWA-2114R), a derivative of the antitumor drug cis- diamminedichloroplatinum(II) (CDDP), using prokaryotic and eukaryotic DNA polymerases. Preincubating activated DNA with CDDP or DWA-2114R reduced its template activity for prokaryotic and eukaryotic DNA polymerases in a dose-dependent manner. DWA2114R required six times greater drug concentration and two times longer incubation time to show the same decrease of the template activity compared to CDDP. Treatment of primed pUC118 ssDNA templates with the two drugs followed by second-strand synthesis by prokaryotic and eukaryotic DNA polymerases revealed that DWA2114R bound to DNA in a similar manner to CDDP and these adducts blocked DNA elongation by DNA polymerases of eukaryotes as well as of prokaryotes. With these two drugs, the elongations by E. coli DNA polymerase I (Klenow fragment), T7 DNA polymerase and calf thymus DNA polymerase α were strongly arrested at guanine-guanine sequences (GG). Stop bands were also observed at adenine-guanine sequences (AG) guanine-adenine-guanine sequences (GAG) and mono-guanine sequence (G). Calf testis DNA polymerase β was also arrested efficiently at AG, GAG and G, but much more weakly at GG. This pattern was common to DWA2114R and CDDP. 相似文献
6.
Effects of N-(2,6-dimethylphenyl)-2-(2-oxo-1-pyrrolidinyl)acetamide (DM-9384) on learning and memory in rats 总被引:1,自引:0,他引:1
Effects of N-(2,6-dimethylphenyl)-2-(2-oxo-1-pyrrolidinyl) acetamide (DM-9384) on learning and memory were studied using four different experimental rat models. In electroconvulsive shock- or scopolamine-induced amnesia in the step-through passive avoidance task, DM-9384 improved both types of amnesia when administered before the training trial. Aniracetam also showed similar but somewhat weaker effects. Furthermore, in the scopolamine amnesia model, an improvement was confirmed with arecoline. The dose-response curves for these compounds were bell-shaped. In the shuttle box active avoidance task, DM-9384 administered daily 1 hr before each training session facilitated the acquisition process of the avoidance response. In addition, the experiment of light-dark discrimination task with positive reinforcement showed that this compound administered daily after each session slightly accelerated the acquisition process of the correct response. These results suggest an ability of DM-9384 to enhance cognitive functions. 相似文献
7.
Masao Amari Katsuji Taguchi Minoru Iwahara K Shibuya Shiro Naoe 《Medical Electron Microscopy》2002,35(4):225-233
To elucidate the effect of fibroblast growth factor on the phenotypical conversion of fibroblasts to mesothelial cells, both immunohistochemical and ultrastructural examinations were carried out on cultured spheroids that were composed of fibroblasts obtained from the parietal pleura of rats with and without addition of antifibroblast growth factor receptor antibody. In the present study, antifibroblast growth factor receptor antibody was employed to block the effect of the autocrine component of fibroblast growth factor in the culture medium. Phenotypical conversion from fibroblast to mesothelial cells was clearly blocked in the experimental group, to which culture medium had been added with antifibroblast growth factor receptor antibody, whereas the control group, cultured without addition of antifibroblast growth factor receptor antibody, showed phenotypical conversion of fibroblasts that was confirmed by the development of macula adherens, microvilli, and positive expression of cytokeratin. These results indicate the possibility that fibroblast growth factor plays a key role in the process of phenotypic conversion of fibroblasts to regenerated mesothelial cells. 相似文献
8.
Changes in central dopaminergic systems with the expression of Shh or GDNF in mice perinatally exposed to bisphenol-A. 总被引:1,自引:0,他引:1
Kazuya Miyagawa Minoru Narita Michiko Narita Keiichi Niikura Hisahiko Akama Yuri Tsurukawa Tsutomu Suzuki 《Nihon shinkei seishin yakurigaku zasshi》2007,27(2):69-75
In the previous study, we reported that exposure to bisphenol-A induced the potentiation of dopamine receptor functions in the mouse limbic area, resulting in supersensitivity to methamphetamine-induced pharmacological actions. The present study was undertaken to investigate whether prenatal exposure to bisphenol-A could produce morphological change in dopaminergic neuron and the pattern of expression of genes regulating the dopaminergic neuron development. Here we found that prenatal and neonatal exposures to bisphenol-A increased the tyrosine hydroxylase- and dopamine transporter-like immunoreactivities in the adult mouse limbic area. The present molecular biological study shows that chronic bisphenol-A treatment produced a significant decrease in the dopaminergic neuron development factors, sonic hedgehog and glial cell line-derived neurotrophic factor, which were also decreased by prenatal exposure to bisphenol-A. These results suggest that chronic exposure to bisphenol-A could disrupt the dopaminergic neurotransmission in the process of dopaminergic neuron development. 相似文献
9.
Kentaroh Miyoshi Minoru Naito Tsuyoshi Ueno Shinji Hato Hideo Ino 《General thoracic and cardiovascular surgery》2009,57(11):629-632
A benign esophageal leiomyoma with abnormally increased fluorine-18-fluorodeoxyglucose uptake on positron emission tomography
(PET) was resected thoracoscopically. The tumor, of which the maximum standardized uptake value of the lesion was 4.7, was
well defined and 38 mm in diameter. Neither mitotic activity nor degeneration was found histologically; and immunoreactivity
for CD34, CD117, MIB-1, and glucose transporter-1 was negative immunohistochemically. A diagnosis of gastrointestinal stromal
tumor was ruled out by an oncogenic kinase gene mutation study. This case cautions against PET-dependent evaluation for malignant
potential of esophageal submucosal tumors. 相似文献
10.