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   33320篇
  免费   1534篇
  国内免费   129篇
耳鼻咽喉   250篇
儿科学   512篇
妇产科学   416篇
基础医学   4436篇
口腔科学   1005篇
临床医学   2296篇
内科学   8401篇
皮肤病学   743篇
神经病学   2394篇
特种医学   1249篇
外科学   5409篇
综合类   146篇
一般理论   1篇
预防医学   1180篇
眼科学   617篇
药学   2294篇
中国医学   65篇
肿瘤学   3569篇
  2022年   324篇
  2021年   583篇
  2020年   277篇
  2019年   390篇
  2018年   535篇
  2017年   424篇
  2016年   506篇
  2015年   507篇
  2014年   698篇
  2013年   856篇
  2012年   1351篇
  2011年   1540篇
  2010年   806篇
  2009年   771篇
  2008年   1344篇
  2007年   1463篇
  2006年   1518篇
  2005年   1504篇
  2004年   1386篇
  2003年   1480篇
  2002年   1535篇
  2001年   1439篇
  2000年   1444篇
  1999年   1246篇
  1998年   459篇
  1997年   340篇
  1996年   308篇
  1995年   260篇
  1994年   231篇
  1993年   225篇
  1992年   906篇
  1991年   804篇
  1990年   729篇
  1989年   740篇
  1988年   675篇
  1987年   689篇
  1986年   602篇
  1985年   571篇
  1984年   365篇
  1983年   306篇
  1982年   158篇
  1979年   242篇
  1978年   181篇
  1977年   152篇
  1975年   153篇
  1974年   155篇
  1973年   169篇
  1970年   151篇
  1969年   154篇
  1967年   155篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Y Yasui  K Suzumori  Y Yagami  T Nakamura 《Gan no rinsho》1987,33(15):1954-1958
Primary squamous cell carcinoma of the endometrium is extremely rare. The patient reported here with squamous cell carcinoma of the endometrium and a synchronous adenocarcinoma of the cervix, represents an extreme, unique example of multiple Müllerian neoplasms. The 70-year-old female had a three-month history of vaginal bleeding. On July 13, 1984, she underwent a radical hysterectomy with a pelvic lymphadenectomy. A histological examination substantiated keratinizing squamous cell carcinoma of the endometrium this tumor extending outside the uterus, and an adenocarcinoma of the cervix. Post-operatively she received chemotherapy and irradiation therapy, but metastases reoccurred and she died on December 1, 1984.  相似文献   
92.
Introduction A few epidemiologic studies have comprehensively attempted to identify risk factors for low bone mineral density (BMD) in elderly Asian women. The purpose of this study was to identify demographic, lifestyle, and biochemical factors correlated with BMD in elderly Japanese women 69 years of age and over.Methods The study design was cross-sectional. The subjects were 583 ambulatory women aged 69 years and over, and their average age was 74.3 (SD 4.4) years. Predictor variables were age, reproductive history, anthropometric indices, grip strength, calcium intake, lifestyle information, and serum 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D (1,25(OH)2D), osteocalcin (OC), and undercarboxylated osteocalcin (ucOC) values. The outcome variable was forearm BMD measured with a DTX-200 osteometer.Results Simple linear regression analyses showed that BMD was significantly positively associated with body height, weight, body mass index, grip strength, serum albumin concentration, and “housework,” and negatively associated with age, years since menopause, age at menarche, number of children, serum 1,25(OH)2D concentration, serum OC concentration, and ucOC concentration. The stepwise multiple regression analysis showed that weight (β=0.00316, SE=0.00028, R2=0.180), age (β=−0.00321, SE=0.00050, R2=0.108), log-transformed serum OC (β=−0.0445, SE=0.0064, R2=0.053), log-transformed serum 1,25(OH)2D (β=−0.0401, SE=0.0074, R2=0.050), “farmwork” (β=0.00904, SE=0.00426, R2=0.005), and serum 25(OH)D concentration (β=0.000281, SE=0.000120, R2=0.003) were significantly associated with BMD.Conclusion It was concluded that body weight is a major predictor of forearm BMD among the factors measured in this study in independent Japanese women 69 years of age and over and that serum 1,25(OH)2D concentration may be associated with cortical BMD. Maintenance of body weight is very important for maintaining BMD in this population, unless a large weight aggravates obesity-related diseases. A follow-up study is needed to confirm these findings.  相似文献   
93.
To examine the effects of transient hyperprolactinemia on in vitro fertilization and embryo transfer, 61 cycles in 50 euprolactinemic ovulatory women with irreparable tubal diseases were stimulated with clomiphene (CC) alone or CC and human menopausal gonadotropin followed by human chorionic gonadotropin (hCG). Serum prolactin (PRL) increased after hCG administration with peak values of 45.4 +/- 4.2 ng/ml on the day of laparoscopic oocyte aspiration. The highest serum estradiol (E2) concentration was found on the day before PRL peak and serum progesterone (P) began to increase after hCG injection concomitant with the PRL rise. The group having 50 ng/ml or more of PRL (34 cycles) had significantly higher levels of E2 during preovulatory and early luteal phase compared to those of the group having less than 50 ng/ml of PRL (27 cycles) but there was no significant difference between the P levels in the two groups. In the higher PRL group 72 (62.1%) of 116 collected oocytes were fertilized and 6 (20.0%) conceived. In the lower PRL group 45 oocytes (58.4%) of 77 were fertilized and 3 (12.5%) became pregnant. These data suggest that elevated serum PRL concentrations may have no effect on fertilization of oocytes in vitro or embryonic development.  相似文献   
94.
To investigate the relationship between the effects of bone turnover and bone marrow cell development in bone cells, we developed a mouse voluntary climbing exercise model. Climbing exercise increased bone volume and transient osteogenic potential of bone marrow. This model would be suitable for investigating the mechanistic roles of mechanical loading. INTRODUCTION: The relationship between bone mass gain and local bone formation and resorption in mechanically loaded bone is not well understood. MATERIALS AND METHODS: Sixty-five C57BL/6J mice, 8 weeks of age, were assigned to five groups: a baseline control and two groups each of ground control and climbing exercise mice for 2 and 4 weeks. Mice were housed in a 100-cm tower and had to climb toward a bottle placed at the top to drink water. RESULTS: Compared with the ground control, bone mineral density of the left femur increased in the climbing mice at 4 weeks. At 2 and 4 weeks, bone formation rate (BFR/BS) of periosteal surface, the cross-sectional area, and moment of inertia were increased in the climbing mice, whereas BFR/BS and eroded surface (ES/BS) of endosteal surface did not differ. The trabecular bone volume (BV/TV) of the proximal tibia increased in climbing mice, and osteoclast surface (Oc.S/BS) and osteoclast number decreased at 2 weeks. At 4 weeks, there were increases in BV/TV and parameters of bone formation, including mineralized surface, mineral apposition rate, and bone formation rate. In marrow cell cultures from the tibia, the number of alkaline phosphatase+ colony forming units-fibroblastic and the area of mineralized nodule formation in climbing mice were increased, and the number of osteoclast-like TRACP+ multinucleated cells was lower at 2 weeks. At 4 weeks, these parameters recovered to the levels of the ground controls. CONCLUSION: Our results indicate that climbing increased trabecular bone volume and reduced bone resorption, with a subsequent increase in bone formation. Intermittent climbing downregulates marrow osteoclastogenic cells and upregulates osteogenic cells initially, but further exercise seemed to desensitize them. Cortical envelopes were enlarged earlier, but the response seems to differ from trabecular bone.  相似文献   
95.
This study assessed the effects of acute as well as long-term administration of fluoxetine, a selective serotonin (5-HT) reuptake inhibitor with anti-depressant properties, on hippocampal (HIP) seizures elicited by electrical stimulation in rats. The fluoxetine effect on HIP seizures was also assessed following long-term treatment with gepirone, a 5-HT1A receptor agonist. Acute single administration of fluoxetine (1, 10 mg/kg; IP) was found to produce no significant effect on HIP seizure activity. Following daily IP administration of fluoxetine (10 mg/kg per day) or gepirone (10 mg/kg per day) for 21 days, animals were given a 7-day drug-free period and then challenged with an acute dose of 10 mg/kg fluoxetine. These treatment regimens resulted in a significantly increased afterdischarge threshold of HIP seizures in response to acute fluoxetine administration. The inhibitory effect of fluoxetine, however, was not present 4 weeks after long-term treatment with either fluoxetine or gepirone. The present results indicate that long-term treatment with these compounds enhances the antiepileptic effect of subsequent fluoxetine administration on the generation of HIP seizures. This effect is possibly related to the well-demonstrated evidence that fluoxetine and gepirone, on long-term treatment, facilitate net 5-HT neurotransmission through desensitization of presynaptic 5-HT autoreceptors.  相似文献   
96.
97.
A Ikoma  N Nakamura  T Miyazaki  M Maeda 《Surgery》1992,111(5):595-600
We report a 64-year-old woman with double cancer of the gallbladder and the common bile duct associated with anomalous junction of the pancreaticobiliary ductal system. Eleven previous cases have been reported to date. From analysis of the 12 cases reviewed, including our patient, double cancer of the gallbladder and the common bile duct accompanied by anomalous junction of the pancreaticobiliary ductal system is characterized by the predominance of well-differentiated and superficial cancer.  相似文献   
98.
Leiomyoblastoma has been regarded as a neoplasm of smooth muscle origin. With recent progress in immunohistostaining techniques, many clinicopathological discrepancies have been pointed out about the origin of leiomyoblastoma. It has been claimed that gastrointestinal non-epithelial tumors should be regarded as stromal tumors in order to study their origin. In the present study, we performed various forms of immunohistostaining in seven cases of leiomyoblastoma to determine their origin. One case expressed desmine and muscle specific actin and was considered to be derived from smooth muscle. Four neoplasms expressed X-100 protein (two cases were also NSE positive) and were thought to be derived from the nerve. Two cases were of unknown derivation. These results suggest that the cells of leiomyoblastoma may arise from a primitive to totipotential cell of neural lineages that may anomalously express smooth muscle filaments.  相似文献   
99.
Patients with stage T3N0~2M0 gastric carcinoma (n = 108) were studied for relevant prognostic factors. Peritoneal lavage cytology (PLC) was performed in all. In univariate analysis, 5-year survival rates were better with smaller serosal invasion (diameter <3.0 cm vs. ≥3.0 cm, 61% vs. 37%, P < 0.05) and fewer metastatic nodes (≤5 vs. ≥6, 57% vs. 29%, P < 0.05). In multivariate analyses, only these two factors were significant. The predictive value of PLC was not shown in both univariate and multivariate analyses. Peritoneal recurrence occured in 14 (22%) of 77 patients with negative PLC, and in 3 (18%) of 17 with positive PLC, the difference being not significant. Our results indicate that PLC is insensitive in predicting the development of peritoneal recurrence. Its role in the estimation of survival is limited, as many will die of visceral or locoregional recurrence if not of peritoneal dissemination.  相似文献   
100.
Endoscopic resection has been accepted as the standard treatment for intramucosal gastric tumors of differentiated type. However, the indication was limited to small tumors to achieve en bloc resection and prevent local recurrence in cases of conventional endoscopic mucosal resection (EMR) such as the strip biopsy and the cap technique. To avoid multi‐fragmental resection, we have developed endoscopic submucosal dissection (ESD) as a new endoscopic resection technique. ESD is a remarkable technique, because we make it possible to remove the lesions en bloc regardless of size, shape, coexisting ulcer, and location. However, it is difficult or impossible to resect recurrent tumors en bloc in conventional EMR owing to hard fibrosis, and some patients need laparotomy. Using ESD, we can dissect the submucosal layer as we directly look at the submucosa, and remove the lesion safely and reliably even in cases of hard fibrosis. The key to treatment of recurrent tumors in ESD are as follows: (i) using enough submucosal injection solution (we use a mixture of Glyceol and 1% 1900 kDa hyaluronic acid preparation); (ii) incising the mucosa without fibrosis; (iii) understanding characteristics of various cutting devices, and changing other devices in difficult situations. In these ways we can remove the majority of the recurrent tumors en bloc. Hence, we consider that ESD is a very effective treatment which achieves excellent en bloc and complete resection rates and enables patients with intramucosal gastric tumors to a recurrent‐free survival even in recurrent tumors.  相似文献   
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