全文获取类型
收费全文 | 21134篇 |
免费 | 1274篇 |
国内免费 | 252篇 |
专业分类
耳鼻咽喉 | 450篇 |
儿科学 | 247篇 |
妇产科学 | 349篇 |
基础医学 | 3570篇 |
口腔科学 | 356篇 |
临床医学 | 1552篇 |
内科学 | 4077篇 |
皮肤病学 | 620篇 |
神经病学 | 1622篇 |
特种医学 | 1462篇 |
外科学 | 2704篇 |
综合类 | 73篇 |
预防医学 | 630篇 |
眼科学 | 481篇 |
药学 | 2140篇 |
中国医学 | 332篇 |
肿瘤学 | 1995篇 |
出版年
2024年 | 11篇 |
2023年 | 147篇 |
2022年 | 493篇 |
2021年 | 781篇 |
2020年 | 378篇 |
2019年 | 559篇 |
2018年 | 748篇 |
2017年 | 505篇 |
2016年 | 859篇 |
2015年 | 1173篇 |
2014年 | 1341篇 |
2013年 | 1470篇 |
2012年 | 2238篇 |
2011年 | 2013篇 |
2010年 | 1242篇 |
2009年 | 1039篇 |
2008年 | 1366篇 |
2007年 | 1200篇 |
2006年 | 985篇 |
2005年 | 955篇 |
2004年 | 772篇 |
2003年 | 656篇 |
2002年 | 584篇 |
2001年 | 191篇 |
2000年 | 169篇 |
1999年 | 112篇 |
1998年 | 88篇 |
1997年 | 79篇 |
1996年 | 72篇 |
1995年 | 41篇 |
1994年 | 44篇 |
1993年 | 27篇 |
1992年 | 30篇 |
1991年 | 50篇 |
1990年 | 25篇 |
1989年 | 27篇 |
1988年 | 27篇 |
1987年 | 25篇 |
1986年 | 18篇 |
1985年 | 17篇 |
1984年 | 10篇 |
1983年 | 8篇 |
1982年 | 5篇 |
1981年 | 11篇 |
1980年 | 9篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1974年 | 6篇 |
1971年 | 5篇 |
1967年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
42.
Fifteen lignans were isolated from the fruits of SCHIZANDRA CHINENSIS, the leaves of MACHILUS THUNBERGII, and the flower buds of MAGNOLIA DENUDATA. They were identified as gomisins, schizandrin, wuweizisu, schizantherin, licarins, and machilin, which inhibited rat liver ACAT with IC (50) values of 25-200 microM. Comisin N is the most potent inhibitor with IC (50) value of 25 microM in these lignans. 相似文献
43.
When liriodendrin or syringin was incubated for 24 h with human intestinal bacteria, two metabolites, (+)-syringaresinol-beta-D-glucopyranoside and (+)-syringaresinol, from liriodendrin and one metabolite, synapyl alcohol, from syringin were produced. The metabolic time course of liriodendrin was as follows: at early time, liriodendrin was converted to (+)-syringaresinol-beta-D-glucopyranoside, and then (+)-syringaresinol. The in vitro cytotoxicities of these metabolites, (+)-syringaresinol and synapyl alcohol, were superior to those of liriodendrin and syringin. 相似文献
44.
Hak Cheol Kwon Byeong Gon Lee Seung Hee Kim Chil Mann Jung Sung Youl Hong Jeung Whan Han Hyang Woo Lee Ok Pyo Zee Kang Ro Lee 《Archives of pharmacal research》1999,22(4):410-413
In bioassay-guided search for inducible nitric oxide synthase (iNOS) inhibitory compounds from higher plants of South Korea, two beta-carboline alkaloids, 4-methoxy-1-vinyl-beta-carboline (1) and 4,8-dimethoxy-l-vinyl-beta-carboline (2) have been isolated from the cortex of Melia azedarach var. japonica. The structures of these compounds were elucidated on the basis of spectroscopic data. Compounds 1 and 2 showed marked inhibitory activity of iNOS on LPS- and interferon-gamma-stimulated RAW 264.7 cells. 相似文献
45.
Cytotoxicity of urushiols isolated from sap of Korean lacquer tree (Rhus vernicifera stokes) 总被引:1,自引:0,他引:1
Hong DH Han SB Lee CW Park SH Jeon YJ Kim MJ Kwak SS Kim HM 《Archives of pharmacal research》1999,22(6):638-641
Cytotoxicities of four urushiols, congeners isolated from the sap of Korean lacquer tree (Rhus vernicifera Stokes), to 29 human cancer cell lines originated from 9 organs were evaluated. Their values of 50% growth inhibition were below 4 microg/ml, and showed cell line specific cytotoxicity. The present result is the first report on the cytotoxicity of urushiols suggesting that they would have an anticancer activity to human cancer cells. 相似文献
46.
Won-Jea Cho Su-Jeong Yoo Byung-Ho Chung Bo-Gil Choi Seung Hoon Cheon Soon-Ho Whang Sin-Kyu Kim Boo-Hyon Kang Chong-Ock Lee 《Archives of pharmacal research》1996,19(4):321-325
Aiming at the development of anticancer agents by modification of phenolic benzo[c]phenanthridine alkaloid, additional hydroxyl group was put on C10 position of fagaridine (1) by a biomimetic synthetic procedure to afford 10-hydroxyfagaridine (12). All of the synthetic intermediates were also screenedin vitro antitumor activities against five different cell lines as well as12. Among them the representative cytotoxic results are shown as follows;p-quinone (11) [ED50 (A549=0.22 μg/ml), (HCT15=0.21 μg/ml), fagaridine (1) (HCT 15=0.41 μg/ml), olefin (6) (HCT 15=0.06 μg/ml), acetal (7) (SKMEL-2=0.07 μg/ml), dihydrofagaridne (10) (A549=0. 38 μg/ml), 10-hydroxyfagaridine (12) (A 549=0.45 μg/ml). From these observation three main remarks can be drawn; (i) the iminium part of benzo[c]phenanthridine is not essential for showing acitvities, (ii) the additional hydroxyl group did not contribute to enhance the cytotoxicity, (iii) the 3-arylisoquinolin-1(2H)-one derivatives were found to display significantin vitro antitumor activity. 相似文献
47.
Aliphatic esters of protocatechuic acid (PA,1), vanillic acid (VA,9) and gallic acid (GA,18) were prepared and their anti-thrombotic effects were evaluated in the mouse model of thrombosis. The aliphatic groups included methyl, ethyl,n-propyl,i-propyl,n-butyl,i-butyl,n-amyl and cyclohexyl.n-Amyl ester of PA (7), i-propyl and cyclohexyl esters of VA (13 and17 respectively) and ethyl ester of GA (20) treatment significantly lowered the death rate and increased the recovery from paralysis due to the thrombotic challenge. From the limited analogs available, it was tentatively concluded that the structural conformation, where carboxy oxygen (=O or-O?) of the carboxyl group (COOH) at C1 and the oxygen function at C3 (either OH or OCH3) are closely situated, is favorable for the esters of PA, VA and GA to be more antithrombotic. 相似文献
48.
The Gastric Bypass for Failed Bariatric Surgical Procedures 总被引:1,自引:0,他引:1
Background: Revision of failed bariatric surgical procedures is a significant challenge for every bariatric surgeon. Methods:
Evaluated are surgical difficulties, management problems and weight loss in patients with distal gastric bypass as a revisionary
procedure. Eighty patients were followed up to 3 years; four were lost to follow-up. Mean age was 43; mean prebariatric surgery
weight 134 kg; height 1.65 meters; body mass index 40.1; ideal body weight 62.7 kg; excess weight 70.5 kg; per cent excess
weight 214%. A 250 cm stomach-to-ileocecal valve segment of small bowel was used, and the biopancreatic secretions were brought
into the terminal ileum 100 cm from the ileocecal valve. Mean pouch size was 63 cc; length of hospital stay 5 days; operative
blood loss 616 cc; operative time 130 min. Results: Intraoperative complications included three splenic injuries (without
splenectomy). Early complications included one deep vein thrombosis, two marginal ulcers, one GI hemorrhage, one wound dehiscence,
one pouch outlet obstruction and one pancreatitis. Late complications included: one death from protein malnutrition/ARDS;
21 hypoproteinemia; six protein malnutrition, and of these, three had hyperalimentation; three cholecystitis; 27 anemia; 22
incisional hernia; two staple-line disruption (reoperated); 26 low serum iron; 11 prolonged (> 6 months) diarrhea; three prolonged
frequent vomiting; and two unrelated deaths (chronic myelogenous leukemia and amyotrophic lateral sclerosis). Mean excess
weight loss was 83% at 12 months; 89% at 24 months; and 94% at 36 months. Conclusion: The distal gastric bypass is fraught
with the operative and immediate post-operative complications experienced in any revisionary bariatric surgery. Distal gastric
bypass is very effective in producing long-term weight loss. Nutritional problems are common but usually easily corrected.
The most serious nutritional complication is protein malnutrition, which must be identified and corrected early. Success of
this procedure is dependent upon patient compliance with proper nutrition and supplements, and regular office follow-up with
monitoring of laboratory data. Patients who are noncompliant are at significant risk for complications. 相似文献
49.
Gwi Eon Kim Yong Bae Kim Nam Hoon Cho Hyun-Cheol Chung Hong Ryull Pyo Jong Doo Lee Tchan Kyu Park Woong Sub Koom Mison Chun Chang Ok Suh 《Clinical cancer research》2004,10(4):1366-1374
PURPOSE: To evaluate the potential of the new prognostic information gained by analyzing the coexpression of epidermal growth factor receptor (EGFR) and cyclooxygenase-2 (COX-2) in cervical cancer patients. EXPERIMENTAL DESIGN: Sixty-eight patients with International Federation of Gynecology and Obstetrics stage IIB squamous cell carcinoma of the uterine cervix, who underwent concurrent chemoradiotherapy between 1993 and 1996, were divided into the following four groups according to their immunoreactivities for EGFR and COX-2 in paraffin-embedded sections: (a). the EGFR-negative/COX-2-negative group (n = 11); (b). the EGFR-negative/COX-2-positive group (n = 8); (c). the EGFR-positive/COX-2-negative group (n = 27); and (d). the EGFR-positive/COX-2-positive group (n = 22). The clinical features, patterns of treatment failure, and survival data in the four groups were compared. RESULTS: Positive immunoreactivity for EGFR and COX-2 was observed in 49 of 68 (72%) and 19 of 68 (28%), respectively. However, no strong correlation was found between the levels of EGFR and COX-2 immunopositivity (R(2) = 0.05, P = 0.07). Patients in the EGFR-positive/COX-2-positive group had a higher likelihood of locoregional recurrence than those in the other three groups (P = 0.02). Of the patients in the four groups, patients positive for both oncoproteins were found to have the worst prognosis with an overall 5-year disease-free survival rate of 55% compared with 91% for the EGFR-negative/COX-2-negative patients, 88% for the EGFR-negative/COX-2-positive patients, and 69% for the EGFR-positive/COX-2-negative patients (P = 0.05, log-rank test). In addition, the synchronous coexpression of the EGFR and COX-2 oncoproteins was found to be an independent prognostic factor by univariate and multivariate analyses (relative risk = 4.0, P = 0.03). CONCLUSIONS: Given these observations, we conclude that the coexpression of EGFR and COX-2 immunoreactivity may be used as a potent molecular risk factor for predicting the poor survival of patients with the International Federation of Gynecology and Obstetrics stage IIB squamous cell carcinoma of the uterine cervix. 相似文献
50.
Interfractional variation in position of the uterus during radical radiotherapy for cervical cancer. 总被引:4,自引:0,他引:4
BACKGROUND AND PURPOSE: This study was conducted to investigate the positional change of the uterus during radiotherapy which can degrade the accuracy of three-dimensional conformal radiotherapy (3DCRT) and intensity modulated radiotherapy (IMRT). PATIENTS AND METHODS: Sixty-six patients received radical radiotherapy for cervical cancer in Samsung Medical Center. For each patient, two MRI scans were taken; one was before beginning radiotherapy and the other was in the third or fourth week of radiotherapy. In T2-weighted MRI images, the positional change of the uterus was quantified by measuring six parameters; the distance from the external uterine opening to the isthmus of the uterus (Dcx), the distance from the isthmus of the uterus to the uterine fundus (Dco), the perpendicular distance of the uterine body to the uterine corpus (Dco-per), the angle between the vertical line and the cervical canal in sagittal images (Acx), the uterine corpus angle from the vertical line in sagittal plan (Aco), the angle between the uterine corpus from an arbitrary bony landmark and a vertical mid line in axial images (Aco-axi) RESULTS: Mean value of change in Dcx+Dco of tumor size during treatment was 8.0 mm in small tumors and 17.9 mm in large tumors. Among 44 anteflexed uterus patients, 5 changed into a retroflexed position. 12 patients (18%) had a greater than 30 degrees variation in any angle. For patients under 60 years, the difference in Acx was statistically significant. CONCLUSIONS: Positional changes of the uterus during radiotherapy should be considered in the treatment planning of 3DCRT or IMRT, particularly in patients under 60 years or those with tumor size greater than 4 cm in diameter. 相似文献