全文获取类型
收费全文 | 7188篇 |
免费 | 548篇 |
国内免费 | 51篇 |
专业分类
耳鼻咽喉 | 74篇 |
儿科学 | 209篇 |
妇产科学 | 148篇 |
基础医学 | 874篇 |
口腔科学 | 198篇 |
临床医学 | 835篇 |
内科学 | 1542篇 |
皮肤病学 | 92篇 |
神经病学 | 365篇 |
特种医学 | 316篇 |
外科学 | 994篇 |
综合类 | 174篇 |
预防医学 | 476篇 |
眼科学 | 96篇 |
药学 | 584篇 |
中国医学 | 18篇 |
肿瘤学 | 792篇 |
出版年
2023年 | 35篇 |
2022年 | 63篇 |
2021年 | 150篇 |
2020年 | 85篇 |
2019年 | 124篇 |
2018年 | 161篇 |
2017年 | 106篇 |
2016年 | 131篇 |
2015年 | 133篇 |
2014年 | 202篇 |
2013年 | 306篇 |
2012年 | 423篇 |
2011年 | 424篇 |
2010年 | 262篇 |
2009年 | 215篇 |
2008年 | 375篇 |
2007年 | 438篇 |
2006年 | 403篇 |
2005年 | 365篇 |
2004年 | 339篇 |
2003年 | 336篇 |
2002年 | 295篇 |
2001年 | 269篇 |
2000年 | 245篇 |
1999年 | 191篇 |
1998年 | 96篇 |
1997年 | 76篇 |
1996年 | 78篇 |
1995年 | 66篇 |
1994年 | 59篇 |
1993年 | 61篇 |
1992年 | 127篇 |
1991年 | 88篇 |
1990年 | 117篇 |
1989年 | 112篇 |
1988年 | 105篇 |
1987年 | 91篇 |
1986年 | 73篇 |
1985年 | 71篇 |
1984年 | 48篇 |
1983年 | 58篇 |
1982年 | 30篇 |
1981年 | 32篇 |
1980年 | 27篇 |
1979年 | 40篇 |
1978年 | 29篇 |
1977年 | 28篇 |
1976年 | 20篇 |
1975年 | 22篇 |
1974年 | 28篇 |
排序方式: 共有7787条查询结果,搜索用时 15 毫秒
101.
PURPOSE: Hepatocellular carcinoma (HCC) is generally considered as a sex hormone-dependent tumor, and hormonal therapy has been proposed as a strategy for the treatment of HCC. The aim of the study is to investigate the effect of megestrol acetate, a synthetic progesteronal agent, on growth of HepG2 cells in vitro and in vivo. EXPERIMENTAL DESIGN: Cell growth in vitro was assessed by a colormetric method, and cell growth in vivo was assessed by tumor volumetrics. RESULTS: Megestrol acetate was shown to inhibit the growth of HepG2 cells in vitro in dose- and time-dependent manners with an IC (50) of 260 microm (24-h incubation). The growth of HepG2 cell-transplanted tumors in nude mice was also inhibited by i.p. injection of megestrol acetate (10 mg/kg/day). The tumor volumes of the megestrol acetate-treated group regressed to 59% of controls by week 6 and to 41% of controls by week 13. Apoptosis following G(1) arrest was observed in megestrol acetate-treated cells and may be a mechanism through which megestrol acetate inhibits HepG2 cells. Megestrol acetate was also demonstrated to have a beneficial effect on the weight gain of tumor-bearing nude mice, and the mean weight of the megestrol acetate-treated animals was higher than that of controls from week 4 of the treatment period, and the differences were statistically significant in week 5 and 6 (P < 0.05, compared with controls). No significant survival advantage was, however, demonstrated in the treatment group. CONCLUSIONS: This study showed that megestrol acetate inhibited the growth of HepG2 cells grown in vitro and in vivo. These data provide useful information for clinical study of megestrol acetate for the treatment of HCC. 相似文献
102.
Edward Chow Lori Holden Joel Rubenstein Monique Christakis Katharina Sixel Marjan Vidmar Joel Finkelstein Charles Hayter Andrew Loblaw Rebecca Wong Ewa Szumacher Cyril Danjoux 《Radiotherapy and oncology》2004,70(3):291-294
Twenty-five patients with osteolytic metastases had computed tomography (CT) scans before and 3 months after palliative radiotherapy. The median % density change following single 8 Gy, 20 Gy/5#, 30 Gy/10# were: 128 (range 98–255), 141 (79–342), and 145 (65–235), respectively. It is feasible to evaluate remineralization of osteolytic lesions with palliative radiotherapy. 相似文献
103.
104.
Nm23 protein expression was analyzed by immunohistochemical staining using formalin-fixed, paraffin-embedded sections from 39 cases with osteosarcomas and compared with the histologic findings and early metastasis for the purpose of detecting nm23 expression in osteosarcoma and elucidating the clinical significance of its expression. Immunoreactivity of nm23 protein was detected in 48.7% of the total cases. There was no statistical difference between nm23 expression and early metastasis, but there was a trend for cases with nm23 expression to progress to early metastasis within 1 year after operation. The role of nm23 as a tumor metastasis suppressor in osteosarcomas appeared less prominent. 相似文献
105.
Lee BR Chow GK Ratner LE Kavoussi LR 《Journal of endourology / Endourological Society》2000,14(10):811-9; discussion 819-20
A shortage of kidney donors has contributed to the interest in laparoscopic live-donor nephrectomy. Three transperitoneal ports are used, as is an AESOP robot. To maintain urine flow, the donor is kept volume expanded during the procedure, and the pneumoperitoneum pressure is minimized. The most critical and hazardous part of the surgery is dissection of the renal artery and vein. Abundant periureteral tissue should be left to protect the blood supply. Harvest of the right kidney is more difficult. Placing the extraction incision in the right upper quadrant and using a Satinsky clamp instead of a stapling device at the origin of the renal vein will provide maximum venous length and help prevent postoperative thrombosis of the allograft. In the first 175 laparoscopic renal harvest procedures at Johns Hopkins, the complication rate was 14%, the rate of open conversion was 2%, and 3% of the patients required transfusions. These rates improved with experience. There was no significant difference in the performance of the allografts or the recovery of the recipients from what is seen after open kidney harvest. Wider acceptance of laparoscopic renal harvest will increase the number of donors and will be helped by development of methods and devices that shorten the learning curve. 相似文献
106.
OBJECTIVES: To re-examine the potential influence of varicocelectomy on testicular volume using scrotal ultrasonography, because it has been reported that total testicular volume (assessed by physical examination) increases after adult varicocele ligation. METHODS: A retrospective review of the testicular volume and semen parameters of 61 men who underwent microsurgical varicocelectomy between 1996 and 1998 was performed. Ultrasound-derived testicular volumes and total motile sperm counts were compared before varicocelectomy and at a mean of 7.2 months postoperatively. RESULTS: Bilateral varicocelectomy was performed in 22 men; 39 men underwent a left-sided procedure only. Overall, no significant change was found in the mean total testicular volume after varicocelectomy compared with preoperatively (24.0 versus 23.9 mL, respectively; P = 0.74). Similarly, the testicular volumes did not change significantly after left or bilateral varicocelectomy (P >0.05). Overall, the mean total motile sperm count increased significantly after varicocelectomy (17. 9 to 25.4, P = 0.05). CONCLUSIONS: This was the first study to examine the effect of adult varicocelectomy on testicular volume using ultrasound-derived measurements of volume. Unlike previous findings, our data suggest that although adult varicocelectomy improves semen quality in most infertile men, it does not result in a significant increase in testicular volume. 相似文献
107.
Immune deficiencies in chronic intestinal pseudo-obstruction 总被引:1,自引:0,他引:1
ML Forchielli MC Young AF Flores D. Richardson CW Lo 《Acta paediatrica (Oslo, Norway : 1992)》1997,86(10):1077-1081
Aim: Chronic intestinal pseudo-obstruction has been associated with urinary disorders, myopathy, and ophthalmoplegia in adults and cholelithiasis in children. We observed a high percentage of total-parenteral-nutrition-dependent patients with pseudo-obstruction and recurrent infections requiring gammaglobulin infusions. Methods: AH records for 23 children with chronic intestinal pseudo-obstruction (10 females and 13 males, mean age 9.8 y ± 4.9 y, range 4–24 y) referred for a nutritional evaluation from 1992 to 1995 were reviewed. Chronic intestinal pseudo-obstruction was diagnosed by clinical, radiographic findings and antroduodenal manometry. Intestinal full-thickness biopsies were performed in seven children. Results: Hypogammaglobulinemia was diagnosed in 18 patients (78%): 16 patients had various immunoglobulin deficiencies and 2 had selective antibody deficiency. Intravenous gammaglobulin was administered in 14 patients. Other medical conditions affecting the children are summarized as follows: autonomic dysfunction in 10 patients (43%), recurrent hypoglycemia in 9 (39%), asthma in 9 (39%), cholecystitis in 7 (30%), low serum carnitine level in 6 (26%), urinary dysfunction in 6 (26%), pancreatitis in 5 (22%), behavioral problems in 5 (22%), myopathy in 2 (9%), idiopathic thrombocytopenia in 2 (8%), velopharyngeal insufficiency in 1 (4%), oculocutaneous albinism in 1 (4%), Pierre-Robin syndrome in 1 (4%), and protein C deficiency in 1 (4%). Munchausen syndrome was suspected in two patients. Conclusions: Chronic intestinal pseudo-obstruction appears to be associated with immune deficiencies. It is unclear if the immune deficiencies, intestinal pseudo-obstruction, and the other medical conditions have a common underlying etiology. Repeated infections may be due to impaired immune function in children with chronic intestinal pseudo-obstruction. We recommend screening for immune deficiencies in children with chronic intestinal pseudo-obstruction. 相似文献
108.
Re-creation of a functional and aesthetically acceptable nose after partial nasal defect requires accurate reproduction of nasal lining, support, and coverage. Most authors recommend an approach to reconstruction with cantilevered bone grafting and paramedian forehead flap placement. The authors propose an alternative approach for selected patients with total or near-total nasal defects combining both alloplastic and autogenous tissues. This method uses vitallium or titanium mesh for the dorsal framework formation, tissue-expanded paramedian forehead flap for soft tissue coverage, and composite chondrocutaneous auricular grafts for tip reconstruction. Nine individuals underwent nasal reconstruction using this method. The indications, details, and potential advantages of this technique are described with accompanying photographic results. A flexible approach using a combination of alloplastic materials and autogenous tissues provides additional reconstructive options for individuals with total or near-total nasal defects. 相似文献
109.
Objective: To identify factors that influence a woman's decision to breast-feed.
Methodology: Five hundred and fifty-six women were recruited from the maternity wards of two Perth hospitals. Data were collected from a self-administered questionnaire completed by participants prior to discharge. Logistic regression analysis was used to determine factors influencing the initiation of breast-feeding.
Results: At discharge from hospital 83.8% of women were breast-feeding, including 6% who were giving complementary formula feeds. After controlling for potentially confounding demographic and biomedical factors, the father's reported preference for breast-feeding was found to be the most important factor influencing a woman's decision to breast-feed (OR 10.18).
Conclusion: Fathers participate in and influence the choice of infant feeding method and should be included in breast-feeding discussions. 相似文献
Methodology: Five hundred and fifty-six women were recruited from the maternity wards of two Perth hospitals. Data were collected from a self-administered questionnaire completed by participants prior to discharge. Logistic regression analysis was used to determine factors influencing the initiation of breast-feeding.
Results: At discharge from hospital 83.8% of women were breast-feeding, including 6% who were giving complementary formula feeds. After controlling for potentially confounding demographic and biomedical factors, the father's reported preference for breast-feeding was found to be the most important factor influencing a woman's decision to breast-feed (OR 10.18).
Conclusion: Fathers participate in and influence the choice of infant feeding method and should be included in breast-feeding discussions. 相似文献
110.
Chin-Hsiang Chien Chien-Chu Huang Yu-Hung Lin Jenta Shen Song-Nan Chow 《Gynecologic oncology》1997,66(3):405-410
Transforming growth factor-α (TGF-α) is a potent mitogenic polypeptide. It is secreted by a variety of transformed cells and tumors, modifying tumor growth through autocrine or paracrine mechanism. In the present study, serum levels of TGF-α were determined by enzyme-linked immunosorbent assay (ELISA) in 27 normal females, 116 patients with benign ovarian tumors, and 42 patients with epithelial ovarian cancers (10 with stage I, 7 with stage II, 19 with stage III, and 6 with stage IV). The ELISA assay could detect a minimum level of serum TGF-α concentration at 10 pg/ml. Serum samples were obtained from normal females and from patients with benign or malignant ovarian tumors before initial surgery. The detectable rates were 11% (3/27) in normal females, 28% (32/116) in benign ovarian tumors, and 62% (26/42) in ovarian cancers. The detectable rates in serous and endometrioid ovarian cancers were 71 and 70%, respectively, which were higher than the rate of 33% in mucinous type. However, there was no obvious relationship between the detectability of serum TGF-α and the stages of ovarian cancers. The mean concentration of TGF-α in ovarian cancer was 159.8 pg/ml, which was significantly higher than 27.7 pg/ml in benign ovarian tumors (P< 0.001) as well as 15 pg/ml in normal females (P< 0.001). The mean concentrations of serum TGF-α in stages I to IV ovarian cancers were 133.5, 96.2, 194.8, and 178.3 pg/ml, respectively. The mean concentration of serum TGF-α in any two stages of ovarian cancers was not statistically different. In conclusion, measurement of serum TGF-α can be used as a supplementary tumor marker to differentiate a malignant ovarian tumor from a benign one. However, the concentration of serum TGF-α has no special relation with the stage of ovarian cancer itself. Because of the small number of stage I ovarian cancers with detectable TGF-α in the present investigation, it would probably not be feasible to differentiate a stage I ovarian cancer from a benign ovarian tumor based only on the level of TGF-α in serum. 相似文献