首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   49023篇
  免费   2166篇
  国内免费   395篇
耳鼻咽喉   616篇
儿科学   1069篇
妇产科学   516篇
基础医学   6382篇
口腔科学   824篇
临床医学   2955篇
内科学   12431篇
皮肤病学   1227篇
神经病学   3712篇
特种医学   1988篇
外科学   8327篇
综合类   217篇
一般理论   6篇
预防医学   1260篇
眼科学   1045篇
药学   3224篇
中国医学   181篇
肿瘤学   5604篇
  2023年   270篇
  2022年   541篇
  2021年   979篇
  2020年   518篇
  2019年   704篇
  2018年   967篇
  2017年   753篇
  2016年   935篇
  2015年   1017篇
  2014年   1327篇
  2013年   1689篇
  2012年   2716篇
  2011年   3021篇
  2010年   1732篇
  2009年   1609篇
  2008年   2858篇
  2007年   3112篇
  2006年   3140篇
  2005年   3103篇
  2004年   3280篇
  2003年   3288篇
  2002年   3250篇
  2001年   689篇
  2000年   641篇
  1999年   781篇
  1998年   818篇
  1997年   699篇
  1996年   656篇
  1995年   552篇
  1994年   509篇
  1993年   523篇
  1992年   479篇
  1991年   455篇
  1990年   379篇
  1989年   370篇
  1988年   358篇
  1987年   304篇
  1986年   275篇
  1985年   231篇
  1984年   235篇
  1983年   182篇
  1982年   156篇
  1981年   179篇
  1980年   151篇
  1979年   129篇
  1978年   129篇
  1977年   102篇
  1976年   85篇
  1975年   82篇
  1973年   63篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
The effects of simultaneous increases in dietary phosphorus (P) and magnesium (Mg) concentrations while maintaining a constant P:Mg ratio on nephrocalcinosis and kidney function in female rats was investigated. Female Wistar rats were fed a control diet (3.12 g P, 0.51 g Mg per kg diet) or a diet having either 3 times the control P and Mg concentrations (3-fold diet; 9.25 g P and 1.42 g Mg per kg diet) or 5 times the control concentrations (5-fold diet; 14.97 g P and 2.37 g Mg per kg diet) for 21 d. The three experimental diets all had same P:Mg molar ratios (control diet; 4.81, 3-fold diet; 5.11, 5-fold diet; 4.96). The 3-fold diet had no significant influence on kidney calcium (Ca), Mg or P concentrations. However, kidney Ca, Mg and P concentrations were significantly higher in rats fed the 5-fold diet than in rats fed the control or 3-fold diets. No significant differences in creatinine clearance were observed among the three groups. Urinary albumin and beta 2-microglobulin excretion were higher in rats fed the 5-fold diet than in rats fed the control or 3-fold diets, while the 3-fold diet had no significant influence on the urinary albumin and beta 2-microglobulin excretion. These results suggest that absolute concentrations of dietary P and Mg are important factors with regard to the development of nephrocalcinosis and diminished kidney function.  相似文献   
102.
We performed laparoscopic appendectomy and drainage to treat panperitonitis due to perforated appendicitis that occurred in a 28‐year‐old woman. We believe this is an appropriate procedure to treat perforated appendicitis because it is safe and minimally invasive, and faster recovery can be expected than after conventional open appendectomy.  相似文献   
103.
104.
Recent studies have indicated that bone marrow stromal cells (BMSC) have the potential to improve neurologic function when transplanted into animal models of central nervous system disorders. However, how the transplanted BMSC restore the lost neurologic function is not clear. In the present study, therefore, we aimed to elucidate whether BMSC express the neuron-specific gamma-aminobutyric acid (GABA) receptor when transplanted into brain that has been subjected to cerebral infarction. METHODS: The BMSC were harvested from green fluorescent protein-transgenic mice and were cultured. The mice were subjected to permanent middle cerebral artery occlusion. The BMSC or vehicle was transplanted into the ipsilateral striatum 7 d after the insult. Using autoradiography and fluorescence immunohistochemistry, we evaluated the binding of 125I-iomazenil and the expression of GABA receptor protein in and around the cerebral infarct 4 wk after transplantation. RESULTS: Binding of 125I-iomazenil was significantly higher in the periinfarct neocortex in the BMSC-transplanted animals than in the vehicle-transplanted animals. Likewise, the number of the GABAA receptor-positive cells was significantly higher in the periinfarct neocortex in the BMSC-transplanted animals than in the vehicle-transplanted animals. A certain subpopulation of the transplanted BMSC expressed a neuron-specific marker, microtubule-associated protein 2, and the marker protein specific for GABAA receptor in the periinfarct area. CONCLUSION: These findings suggest that BMSC may contribute to neural tissue regeneration through migrating toward the periinfarct area and acquiring the neuron-specific receptor function.  相似文献   
105.
Primary aqueductal stenosis is one of the main causes of congenital hydrocephalus in humans and experimental models. The congenitally hydrocephalic rat strain LEW/Jms is one such model. In this report, we describe further detailed histological features of periaqueductal structure, including the posterior commissure, subcommissural organ (SCO), and ependyma, and discuss the changes in these structures in relation to the cause of hydrocephalus. Coronal sections of the aqueduct in normal rats showed that the usual ependyma was absent in the center of the base facing the dorsal side, which was replaced by tall columnar cells. On the other hand, in hydrocephalic rats the ependyma encircled the aqueductal cavity. In midline sagittal sections, normal and hydrocephalic rats showed the SCO, although the SCO in hydrocephalic rats was shorter than in normal rats. There was also a marked difference between normal and hydrocephalic rats in the dorsoventral dimension of the rostral midbrain. In hydrocephalus, this dimension was large in comparison with normal rats. The superior collicular commissure located caudal to the posterior commissure ran along the ventral side of the midbrain in rats with hydrocephalus, and there was a cell-depleted area just dorsal to the superior collicular commissure. The same findings were observed from the 17th day of gestation until the postnatal period. Although the role of the SCO has been widely discussed from the viewpoint of secretory function, the present study indicated that this organ might be involved in the formation of the shape of the aqueduct.  相似文献   
106.
Using a questionnaire survey, we analyzed the relationship between the frequency of breast self-examination (BSE) and the clinical stage and course of breast cancer in Japanese patients. BSE had been performed monthly by only 5.4% of the patients (M group), occasionally by 35.4% (O group), and not at all by 59.2% (N group). There was a positive relationship between more frequent BSE and an earlier clinical stage, the percentages of Tis/stage 0 and I for the M, O, and N groups being 83%, 44%, and 36%, respectively (P<0.05). The mean maximum tumor diameters for the three groups were 1.7cm, 2.5cm, and 3.0cm, respectively. The tumor size in the M and O groups was significantly smaller than that in the N group atP<0.01 andP<0.05, respectively. The percentages of patients in the M, O, and N groups who underwent breast-conserving therapy were 42%, 11%, and 19%, respectively, with patients who had performed monthly, BSE more frequently undergoing breast-conserving therapy (P<0.05). At a median follow-up time of 34 months, 0%, 3.8%, and 7.6% of the patients from the M, O, and N groups, respectively, had died of breast cancer, the overall survival curve of the M group being significantly better than that of the N group (P<0.01). This retrospective study suggests the positive correlation of BSE frequency with earlier detection, and a more favorable clinical course in Japanese breast cancer patients.  相似文献   
107.
108.
Abstract: The vitamin B12 (VB12) parameter was studied in the serum and cerebrospinal fluid (CSF) of 14 demented patients. Eleven of these patients were in a state of dementia of the degenerative type such as Alzheimer's disease, senile dementia and Pick's disease. The serum VB12 concentration in all the patients was within normal limits, I.e. 500–1,300 pg/ml. There was no significant difference between the CSF-VBl2 levels and the severity of dementia. The serum and CSF-VB12 levels of the demented patients did not show any significant elevation after the oral administration of CH3–Bl2, 2 mg per day. On the other hand, there was a marked elevation of both the serum and CSF-VB12 after an oral medication (2 mg per day) plus intramuscular administrations (500 μg per day). These results confirm that the intramuscular administration of CH3–B12 is an effective way to get a higher value of the serum and CSF-VB12 levels.  相似文献   
109.
Kampo, a Japanese-Chinese traditional herbal medicine, has been used for the treatment of various diseases for about 3,000 years in China. Among herbal medicines, Sairei-to is well known for improving the symptoms of rheumatoid arthritis (RA) and other collagen diseases. However, its immunosuppressive effects on autoimmune cutaneous phenomena are not completely understood. We investigated the effects of Sairei-to on the development of lupus dermatoses in autoimmune-prone MRL/Mp-lpr/lpr (MRL/lpr) mice, an animal model which spontaneously develops skin lesions similar to those seen in human lupus erythematosus. Virgin female MRL/lpr mice at 1 month of age, which were treated orally with Sairei-to, had reduced amounts of IgG deposition at the dermoepidermal junction, titers of anti-DNA antibodies and rheumatoid factor, and lymphoproliferation. These results support the use of traditional herbal medicines in patients with human RA and systemic lupus erythematosus.  相似文献   
110.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号