全文获取类型
收费全文 | 28957篇 |
免费 | 1460篇 |
国内免费 | 188篇 |
专业分类
耳鼻咽喉 | 245篇 |
儿科学 | 459篇 |
妇产科学 | 465篇 |
基础医学 | 3678篇 |
口腔科学 | 623篇 |
临床医学 | 1903篇 |
内科学 | 7635篇 |
皮肤病学 | 450篇 |
神经病学 | 2276篇 |
特种医学 | 1072篇 |
外科学 | 4973篇 |
综合类 | 149篇 |
一般理论 | 1篇 |
预防医学 | 789篇 |
眼科学 | 655篇 |
药学 | 2120篇 |
中国医学 | 97篇 |
肿瘤学 | 3015篇 |
出版年
2023年 | 185篇 |
2022年 | 360篇 |
2021年 | 588篇 |
2020年 | 389篇 |
2019年 | 476篇 |
2018年 | 624篇 |
2017年 | 422篇 |
2016年 | 605篇 |
2015年 | 618篇 |
2014年 | 793篇 |
2013年 | 955篇 |
2012年 | 1617篇 |
2011年 | 1683篇 |
2010年 | 914篇 |
2009年 | 747篇 |
2008年 | 1415篇 |
2007年 | 1500篇 |
2006年 | 1365篇 |
2005年 | 1431篇 |
2004年 | 1449篇 |
2003年 | 1278篇 |
2002年 | 1351篇 |
2001年 | 884篇 |
2000年 | 893篇 |
1999年 | 829篇 |
1998年 | 354篇 |
1997年 | 285篇 |
1996年 | 235篇 |
1995年 | 217篇 |
1994年 | 221篇 |
1993年 | 183篇 |
1992年 | 566篇 |
1991年 | 490篇 |
1990年 | 485篇 |
1989年 | 489篇 |
1988年 | 445篇 |
1987年 | 375篇 |
1986年 | 366篇 |
1985年 | 368篇 |
1984年 | 267篇 |
1983年 | 202篇 |
1982年 | 90篇 |
1979年 | 172篇 |
1978年 | 126篇 |
1977年 | 125篇 |
1974年 | 92篇 |
1972年 | 89篇 |
1971年 | 95篇 |
1968年 | 95篇 |
1967年 | 90篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
在免眼中进行经瞳孔阈值下温热疗法的组织学效应和蛋白表达 总被引:1,自引:0,他引:1
Yoshihiro Morimura Annabelle A. Okada Atsushi Hayashi Sayuri Fujioka Sumie Kawahara Tetsuo Hida 李扬 《美国医学会眼科杂志(中文版)》2005,17(3):185-186
目的:研究阈值下经瞳孔温热疗法(TTT)对视网膜组织学的效应。方法:对正常视网膜色素的兔眼进行TTT,通过1个810nm激光二极管产生直径为1.2mm能量为50mW的光斑,持续时间为15、30和60秒。4周后进行荧光血管造影并摘除眼球,通过电子显微镜和免疫组化染色来检查。 相似文献
63.
T Urakawa Y Nagahata S Fukuoka T Hayashi T Takata S Matsui M Nakamoto Y Hirai K Kumagai Y Saitoh 《Nihon Geka Gakkai zasshi》1986,87(2):180-188
We prepared obstructive jaundice models in rats in order to study the mechanism of acute ulceration in obstructive jaundice centering on impediments to gastric wall blood flow and changes in gastric mucosal NA and PGE2 when the rats were subjected to water immersion restraint stress. The results were: In the obstructive jaundice 2 weeks group, when subjected to water immersion restraint stress, gastric mucosal NA reached a dried up stage from the incipient stage, causing gastric mucosal impediments at the same time, showing a significant decrease of gastric mucosal PGE2. Intragastric pH was at a similar level of excessive acidity in all groups; gastric acid is believed to be a secondary factor promoting ulceration. Gastric mucosal PGE2 showed a significant decrease coinciding with the increase in ulceration index, being a possible factor of ulceration; it is also presumed to regulate gastric wall blood flow alternatively with gastric mucosal NA. Pre-treatment with PGE2 prior to loading stress resulted in a decrease in gastric wall blood flow being significantly controlled. The administration of PGE2 brought about an improvement in gastric wall blood flow and a consequent increase in gastric mucosal NA, being judged effective for acute ulceration in obstructive jaundice. 相似文献
64.
To clarify the role of serotonin in cerebral ischemia, we examined the effects of selective serotonin reuptake inhibitors, citalopram and clomipramine, on ischemic neuronal damage in the gerbil. Pretreatment with citalopram (40 mg/kg i.p.) and clomipramine (20 mg/kg i.p.) protected against neuronal destruction of hippocampal CA1 pyramidal cells following 5 min of forebrain ischemia. Furthermore, microdialysis assays showed that a striking increase in extracellular excitatory amino acid levels during ischemia was significantly inhibited by pretreatment with citalopram and clomipramine. However, citalopram (40 mg/kg i.p.) did not alter the extracellular amino acid concentrations in normal gerbils. Thus, serotonin reuptake inhibitors have a protective effect against ischemic neuronal damage. Furthermore, the present result suggests that the protective effect is mediated through prevention of the accumulation of extracellular excitatory amino acids during and after ischemia. 相似文献
65.
S Ueno R Ootsuka Y Hayashi H Nishitani N Shirakawa T Hashimoto 《Nihon Igaku Hōshasen Gakkai zasshi. Nippon acta radiologica》1992,52(10):1417-1423
Intracranial MR imaging was performed in five patients with achondroplasia. All patients had narrowing of the subarachnoid space at the level of the foramen magnum that was mainly due to protrusion of the posterior aspect. Three patients had compressive deformities of the brainstem and/or upper cervical spine. Among them, two patients had deformities of the pons. Relative upward displacement of the brainstem was seen in all patients. Hydrocephalus was seen in three patients. 相似文献
66.
M. Ito T. F. Lang M. Jergas M. Ohki M. Takada T. Nakamura K. Hayashi H. K. Genant 《Calcified tissue international》1997,61(2):123-128
This study examined trabecular bone mineral density (BMD) in Japanese women with and without spinal fracture, and compared
the results to American women with and without fracture. The quantitative computed tomography (QCT) systems used at the University
of California, San Francisco (UCSF) and at Nagasaki University were cross-calibrated. Normative BMD was assessed with the
K2HPO4 liquid phantom in 538 Americans aged 20–85 years, and with the B-MAS200 phantom in 577 Japanese aged 20–83 years. These BMD
were adjusted for use with the Image Analysis solid phantom using the result of cross-calibration. The trabecular BMD in 111
postmenopausal American women (55 with fracture), and in 185 postmenopausal Japanese women (67 with fracture) were compared
for investigation of the difference in BMD values relative to fracture status. The absolute BMD values in Japanese were lower
than those in Americans, and the differences were greater with advancing age. The magnitude of the BMD difference was 8.6,
20.5, 38.1 mg/cm3 in women aged 20–24 years, 40–44 years, 60–64 years, respectively. In premenopausal women, BMD began to decrease at the age
of 20 in Japanese, whereas the peak bone mass was maintained until the age of 35 in the American women. In immediate postmenopausal
women, BMD significantly decreased in both populations. In later postmenopausal women, BMD significantly decreased with age
in the Japanese women but decreased less rapidly in the American women. The aging decrease of BMD was 1.4% and 2.2% per year
in the later postmenopausal American and Japanese women, respectively. The fracture threshold is considered to be lower in
Japanese women. However, the BMD difference between American and Japanese women with fracture was similar to that without
fracture. The Z-scores of fracture subjects versus controls were 2.9 in American and 1.8 in Japanese women. In conclusion,
Japanese women were found to have a lower BMD and lower fracture threshold than American women. The significant decrease of
spinal trabecular BMD in late postmenopause is potentially responsible for the higher prevalence of spinal fracture in Japanese
women.
Received: 18 December 1995 / Accepted: 23 September 1996 相似文献
67.
We performed a chromosome analysis of 26 pediatric brain tumors, including 20 primitive neuroectodermal tumors (PNETs), 5 astrocytomas, and I immature teratoma. Specimens were treated with collagenase, placed in overnight or short-term cultures, and harvested for chromosome analysis. Numerical and/or structural abnormalities were noted in 14 of the 20 PNETs and 4 of the 5 astrocytomas. In 13 PNETs, so-called medulloblastoma in the cerebellum, an i(17q) was the most frequent structural abnormality, accounting for 30% (4/13). Double minute chromosomes (dmin) were observed in one tumor. Near-diploidy was demonstrated in three of these PNETs, hyperdiploidy in three, and near-tetraploidy in three. We could not find any correlation of these cytogenetic findings with the prognosis. In the remaining seven PNETs other than medulloblastoma, the karyotypes of five PNETs demonstrated a variety of numerical and structural abnormalities. As to the astrocytomas, losses of chromosomes 7 and 9 with dmin were observed in two, and structural abnormalities of chromosomes 1 and 17 were also observed in two tumors. In our limited cases, however, we could not find the same chromosome abnormalities that are well known in adult astrocytomas. A congenital immature teratoma showed hyperdiploidy with increased numbers of chromosomes 3, 6, and 12. We conclude that i(17q) is an important chromosome abnormality in medulloblastomas, and that the oncogenesis of pediatric astrocytomas might be different cytogenetically from that of adult astrocytomas. 相似文献
68.
Mariko Hosono H. Kobayashi Ryota Fujimoto Kazushige Tsutsui Yoshihiko Kotoura Tadao Tsuboyama Hikaru Hayashi Takashi Nakamura Junji Konishi 《Skeletal radiology》1997,26(9):525-528
Objective. To clarify the MRI features of parasymphyseal insufficiency fractures of the os pubis. Design and patients. MRI was performed in four postmenopausal women with parasymphyseal insufficiency fractures. The diagnosis was confirmed with
plain films in every patient. T1-weighted and T2-weighted images were obtained in four patients using a 1.5-T unit. Postcontrast
T1-weighted imaging was also done in three patients. Results and conclusions. MRI of pubic parasymphyseal insufficiency fracture characteristically demonstrates a hyperintense mass lesion with a hypointense
rim on T2-weighted imaging, showing peripheral and septal enhancement after contrast administration. It is important to have
this entity in mind in patients with osteoporosis, especially in patients with a history of pelvic irradiation for malignant
disease, so as not to misinterpret it as a chondroid tumor or bone metastasis. 相似文献
69.
H J Jeon T Akagi Y Hoshida K Hayashi T Yoshino T Tanaka J Ito T Kamei K Kawabata 《Cancer》1992,70(10):2451-2459
BACKGROUND. The breast is rarely a primary site for extranodal malignant lymphoma. Most reported primary non-Hodgkin malignant lymphomas of the breast (PBL) are of B-cell phenotype. METHODS. Histologic and immunohistochemical analyses of seven patients with PBL and a statistical analysis of 152 patients with PBL reported in the Japanese literature were performed. RESULTS. Malignant lymphoma could not be predicted preoperatively with clinical and radiologic findings; breast carcinoma, fibroadenoma, and phyllodes tumor were the preoperative diagnoses. All patients were women; they ranged in age from 31 to 80 years (mean, 57.6 years). The right breast was involved initially in five patients. In four, only the breast was involved (Stage I), whereas in three, the ipsilateral axillary lymph nodes (Stage II) were involved at diagnosis. According to the Working Formulation, all patients belonged to the intermediate grade and were classified as having diffuse large cell (five patients) or mixed (two patients) lymphoma. Immunophenotypic analysis revealed that all patients had B-cell lymphoma. No patients had lymphoepithelial lesions, which is the characteristic feature in categorizing a lymphoma as a mucosa-associated lymphoid tissue (MALT) lymphoma. A statistical analysis of the patient reported in the Japanese literature has divided PBL into two types: a bilateral type that affects younger women and a unilateral type that has a broad age distribution, but preponderantly occurs in older women. The age and stage at diagnosis were significant prognostic factors in predicting the survival time, but the location and size of the tumor at initial presentation, histopathologic type, terminal leukemic manifestation, and treatment modality were not. CONCLUSIONS. This study indicates that most PBL are diffuse large cell lymphoma of B-cell phenotype and that the age and stage at diagnosis are significant prognostic factors. 相似文献
70.
Estrogenic Induction of NADPH- Diaphorase Activity in the Preoptic Neurons Containing Estrogen Receptor Immunoreactivity in the Female Rat 总被引:1,自引:0,他引:1
Nitric oxide and estrogen have been shown to play a critical role in the control of female reproductive function. In order to determine an anatomical relationship between nitric oxide generating neurons and estrogen target neurons, NADPH-diaphorase histochemistry was combined with estrogen receptor immunohistochemistry in the female medial preoptic area. While only a few weakly stained neurons for NADPH-diaphorase were found in ovariectomized control rats, a drastic increase in NADPH-diaphorase activity was observed in the medial preoptic nucleus of estradiol-treated ovariectomized animals. The total number of NADPH-diaphorase neurons in the estradiol-treated group increased three-fold relative to controls, and more than 80% of those neurons contained estrogen receptor-immunoreactivity in their nuclei. Since neuronal NADPH-diaphorase is nitric oxide synthase, the present result suggests that nitric oxide synthase activity can be positively regulated by estradiol in neurons containing estrogen receptor in the female medial preoptic nucleus. 相似文献