全文获取类型
收费全文 | 2848篇 |
免费 | 132篇 |
国内免费 | 4篇 |
专业分类
耳鼻咽喉 | 73篇 |
儿科学 | 129篇 |
妇产科学 | 36篇 |
基础医学 | 239篇 |
口腔科学 | 61篇 |
临床医学 | 207篇 |
内科学 | 483篇 |
皮肤病学 | 22篇 |
神经病学 | 224篇 |
特种医学 | 176篇 |
外科学 | 535篇 |
综合类 | 97篇 |
预防医学 | 132篇 |
眼科学 | 230篇 |
药学 | 168篇 |
中国医学 | 11篇 |
肿瘤学 | 161篇 |
出版年
2023年 | 18篇 |
2022年 | 56篇 |
2021年 | 114篇 |
2020年 | 41篇 |
2019年 | 60篇 |
2018年 | 93篇 |
2017年 | 71篇 |
2016年 | 86篇 |
2015年 | 77篇 |
2014年 | 107篇 |
2013年 | 146篇 |
2012年 | 227篇 |
2011年 | 226篇 |
2010年 | 133篇 |
2009年 | 132篇 |
2008年 | 173篇 |
2007年 | 162篇 |
2006年 | 126篇 |
2005年 | 143篇 |
2004年 | 117篇 |
2003年 | 98篇 |
2002年 | 108篇 |
2001年 | 53篇 |
2000年 | 36篇 |
1999年 | 35篇 |
1998年 | 18篇 |
1997年 | 13篇 |
1996年 | 8篇 |
1993年 | 12篇 |
1992年 | 19篇 |
1991年 | 25篇 |
1990年 | 24篇 |
1989年 | 30篇 |
1988年 | 18篇 |
1987年 | 20篇 |
1986年 | 11篇 |
1985年 | 8篇 |
1984年 | 8篇 |
1983年 | 11篇 |
1981年 | 17篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1977年 | 6篇 |
1976年 | 9篇 |
1975年 | 8篇 |
1974年 | 6篇 |
1973年 | 10篇 |
1972年 | 6篇 |
1971年 | 7篇 |
1969年 | 6篇 |
排序方式: 共有2984条查询结果,搜索用时 25 毫秒
21.
Dane Christina Daoud MD Elena M. S. Cartagena MD MSc Katherine J. P. Schwenger RD PhD Nicha Somlaw MD Leah Gramlich MD Scott Whittaker MD David Armstrong MD Brian Jurewitsch PharmD Matreyi Raman MD Donald R. Duerksen MD James D. McHattie MD Johane P. Allard MD 《JPEN. Journal of parenteral and enteral nutrition》2022,46(2):348-356
22.
Dominika Seidman Marielle Cavrois Joan F. Hilton Nadia R. Roan Sarah Averbach Margaret Takeda Eric Chang Nandhini Raman Ruth Greenblatt Barbara L. Shacklett Karen Smith-McCune 《Contraception》2021,103(1):44-47
IntroductionEx vivo fusion assays offer an efficient method for studying HIV-1 entry associated with contraceptive use and pregnancy outside of cohort studies of HIV-1 incidence.MethodsWe measured ex vivo HIV-1 fusion to cervical or endometrial immune cells from three groups of women: pregnant, non-pregnant not using hormonal or intrauterine contraception, and using depot medroxyprogesterone acetate (DMPA).Results and conclusionsThere was no excess susceptibility to HIV-1 fusion of cells from pregnant women or DMPA users compared to controls. Although the number of target cells in endometrium was higher in DMPA users compared to controls, HIV-1 fusion was lower.ImplicationsIn ex vivo assays, HIV-1 showed no enhanced fusion to cervical immune cells from pregnant women or DMPA users compared to controls, and lower fusion to endometrial immune cells from DMPA users. This assay is useful for studying hormonal and contraceptive effects on HIV-1 entry into reproductive tract immune cells. 相似文献
23.
Background. Prevalence of type 2 or non insulin dependent diabetes mellitus is high among Indians living in India as well as abroad. Prevalence among persons of Indian origin in many countries is greater than that of people of other ethnic extraction. The Indian state of Kerala is distinguished by a high level of achievement in the health sector, characterised by both lower mortality rates and greater density of health care institutions that ensure access to most people. These attributes make the prevalence of diabetes and the pattern of its management in Kerala worth studying. Objective. To estimate the prevalence of diabetes among persons 20 years or older in an urban housing settlement in Trivandrum city, the capital of Kerala, as well as study the management of the disease in subjects affected. Design. Cross sectional survey for detecting diabetes and other chronic diseases in all willing residents of an urban housing settlement in Trivandrum, the capital city of Kerala, as part of a preventive campaign against lifestyle diseases. Fasting plasma glucose, serum triglycerides, cholesterol, height, weight and blood pressure were measured, and a detailed questionnaire administered to ascertain previous diabetic status and management. Results. Overall prevalence of type 2 diabetes is 16.3%. In the 30-64 age group, age standardised prevalence is 13.7%. Gender differences in prevalence are negligible. Greater prevalence is associated with advancing age, body mass index above 24.99, sedentary habits, serum total cholesterol > 239, serum triglycerides > 149, hypertension and smoking. Compared to non-diabetics, diabetics have greater mean and range of fasting plasma glucose values (8.87 + /-3.6 mM/l as against 4.34 + /-0.53 mM/l). 32 out of 38 diabetics among the subjects (82.4%) were already diagnosed even before the survey; of them, 89% were on medication. 3% of subjects had impaired fasting glucose, or FPG level between 110-125 mg/dl. Conclusion. Prevalence of type 2 diabetes among a group of urban residents in Trivandrum city in Kerala is very high. This is associated also with a high detection rate and compliance to treatment. 相似文献
24.
Hui Tian Junhai Ou Stephen C Strom Raman Venkataramanan 《Drug metabolism and disposition》2005,33(3):329-335
Hepatic regeneration is very critical to the success of living donor liver transplantation, which allows a reduced size liver to grow in size to accommodate the requirements of both the donor and the recipient. The objectives of this study were to evaluate 1) the hepatic metabolism of the two immunosuppressive drugs, tacrolimus and mycophenolic acid (MPA), and 2) the pharmacokinetics of tacrolimus and mycophenolic acid at various time points after initiation of hepatic regeneration by partial hepatectomy in rats. The hepatic intrinsic clearance of tacrolimus was decreased to 70% and 51% of the control level at the 24th h and the 6th day, respectively, but returned to normal level by day 14. The total body clearance of tacrolimus was reduced transiently but recovered completely by day 18. The hepatic intrinsic clearance of MPA was decreased to 52% and 51% of that in control rats at the 24th h and the 6th day, respectively, but recovered to normal level by day 14. The total body clearance of MPA was reduced at the 24th h but recovered by day 6. The magnitude of reduction in the clearance of tacrolimus and MPA was much smaller than what was predicted from in vitro data. The elimination clearance of MPA glucuronide was also impaired during hepatic regeneration but recovered to normal level with time. In conclusion, the pharmacokinetics of tacrolimus and mycophenolic acid were altered during hepatic regeneration but recovered completely at different rates over time. Caution must be exercised in extrapolating in vitro data to in vivo conditions during hepatic regeneration. 相似文献
25.
Creation of radiofrequency lesions in a porcine model: correlation with sonography, CT, and histopathology 总被引:6,自引:0,他引:6
Raman SS Lu DS Vodopich DJ Sayre J Lassman C 《AJR. American journal of roentgenology》2000,175(5):1253-1258
OBJECTIVE: We studied the correlation between sonographic and CT appearances of radiofrequency thermal lesions created in porcine liver and histopathologic findings to evaluate the accuracy of these techniques in revealing the extent of tissue necrosis. MATERIALS AND METHODS: We used sonographic guidance and a 2.0-cm-diameter, eight-prong retractable radiofrequency electrode to view 12 hepatic lesions that were created in five pigs. Biphasic helical CT was performed 12-48 hr after ablation. The animals were sacrificed immediately after CT, and their livers were histopathologically examined. The maximum lesion size in the long and short axes as measured on CT and sonography was then correlated with the histopathologically determined lesion size. RESULTS: On sonography, lesions changed rapidly within 5 min after the termination of ablation. An early echogenic cloud became peripherally hypoechoic with a variable thin echogenic rim. Early (0-2 min after ablation) sonograms led to an underestimation of true lesion sizes on histopathology (r = 0.3-0.49; p < 0.05). Delayed (2-5 min after ablation) sonograms also led to an underestimation of true lesion size (r = 0.5-0.62; p < 0.05); however, lesions were larger and better demarcated. Biphasic contrast-enhanced helical CT revealed avascular lesions surrounded by hyperemic rims that closely correlated with true pathologic lesions size (r = 0.93-0.95; p < 0. 05). Lesions with hyperemic rims that were measured on CT led to overestimations of true lesion size. CONCLUSION: Sonography led to underestimations of the true size of ablated lesions within the first 5 min after creation; however, delayed images provided better results. The avascular lesion measured on contrast-enhanced helical CT closely correlated with the size of ablated tissue; therefore, contrast-enhanced CT is preferred for serially monitoring the effect of radiofrequency ablation. 相似文献
26.
Palliation of advanced/recurrent esophageal carcinoma with high-dose-rate brachytherapy 总被引:7,自引:0,他引:7
Sharma V Mahantshetty U Dinshaw KA Deshpande R Sharma S 《International journal of radiation oncology, biology, physics》2002,52(2):310-315
PURPOSE: The aim was to assess the improvement in swallowing status, complication rate, and overall survival. PATIENTS AND METHODS: Fifty-eight patients with advanced/recurrent esophageal carcinoma were treated for palliation with high-dose-rate intraluminal brachytherapy (HDR-ILRT) with a remote afterloading microSelectron unit (192Ir source) with or without external radiation from November 1994 to May 2000 at the Tata Memorial Hospital. The mean age was 64 years. The mid-third of the esophagus was involved in 38 patients (66%). The group was comprised of 37 previously untreated patients (29 with < or = 50% Karnofsky performance status and old age, 4 with metastatic disease, and 4 with second primary esophageal lesions) and 21 patients with post-treatment recurrent tumors. Thirty-eight patients (65%) received intraluminal brachytherapy alone, whereas the remaining 20 patients (35%) received a combination of external and intraluminal radiation therapy. All patients received 2 fractions of HDR-ILRT 1 week apart with 600 cGy per fraction at 1 cm off axis. RESULTS: Overall improvement in swallowing status was seen in 22 patients (48%), and 24 (41%) maintained pretreatment swallowing status. Median dysphagia-free survival was 10 months. Overall complication rates were 30%, with stricture seen in 9 patients (15%), ulceration in 6 (10%), and tracheo-esophageal fistula in 3 patients (5%). Complication rates were higher in the post-treatment group (38%) than in the previously untreated group (27%) (p = 0.29). The median overall survival for the entire group was 7 months. Median survival was better, although not significantly, for the previously untreated cohort: 7.8 months vs. 6 months for the post-treatment group (p = 0.77). CONCLUSION: HDR-ILRT brachytherapy achieves good palliation with acceptable complications in advanced/recurrent esophageal carcinoma. 相似文献
27.
Ibadur Rahman Priyanka Singh Nirendra Dev Mohammed Arif Faiz Noor Khan Yusufi Ameer Azam M. Masroor Alam Sandeep Singh Jasgurpreet Singh Chohan Raman Kumar Lovneesh Sharma Elsayed Tag-Eldin Shubham Sharma Muhammad Rizal Muhammad Asyraf 《Materials》2022,15(22)
The findings of an extensive experimental research study on the usage of nano-sized cement powder and other additives combined to form cement–fine-aggregate matrices are discussed in this work. In the laboratory, dry and wet methods were used to create nano-sized cements. The influence of these nano-sized cements, nano-silica fumes, and nano-fly ash in different proportions was studied to the evaluate the engineering properties of the cement–fine-aggregate matrices concerning normal-sized, commercially available cement. The composites produced with modified cement–fine-aggregate matrices were subjected to microscopic-scale analyses using a petrographic microscope, a Scanning Electron Microscope (SEM), and a Transmission Electron Microscope (TEM). These studies unravelled the placement and behaviour of additives in controlling the engineering properties of the mix. The test results indicated that nano-cement and nano-sized particles improved the engineering properties of the hardened cement matrix. The wet-ground nano-cement showed the best result, 40 MPa 28th-day compressive strength, without mixing any additive compared with ordinary and dry-ground cements. The mix containing 50:50 normal and wet-ground cement exhibited 37.20 MPa 28th-day compressive strength. All other mixes with nano-sized dry cement, silica fume, and fly ash with different permutations and combinations gave better results than the normal-cement–fine-aggregate mix. The petrographic studies and the Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) analyses further validated the above findings. Statistical analyses and techniques such as correlation and stepwise multiple regression analysis were conducted to compose a predictive equation to calculate the 28th-day compressive strength. In addition to these methods, a repeated measures Analysis of Variance (ANOVA) was also implemented to analyse the statistically significant differences among three differently timed strength readings. 相似文献
28.
Glycyrrhetinic acid-modified chitosan (mGA-suc-CTS) is used as liver-targeted carrier for drug delivery. In this study, nanoparticles were prepared by ionic gelation process, and glycyrrhetinic acid act as the targeting ligand. The structure of the product was confirmed by IR and NMR techniques. The main aim of this study was to deliver atorvastatin directly to the liver by using same conjugate and reduce the associated side-effects, i.e. hepatotoxicity at high dose. Characterization of the developed formulation was performed by differential scanning calorimetry, particle size measurements and cellular uptake studies. Release profile, pharmacokinetics studies and organ distribution studies showed that developed formulation shows a relative higher liver uptake. The optimized formulation showed increased plasma concentration than the CTS nanoparticles as well as plain drug and the accumulation in the liver was nearly 2.59 times more than that of obtained with the CTS nanoparticles. Pharmaceutical and pharmacological indicators suggested that the proposed strategy can be successfully utilized for liver targeting of therapeutics. 相似文献
29.
Praveen Kerala Varma Raman Krishna Kumar Gopichettipalayam Subbaratnam Bhuvaneshwar Neethu Krishna 《Indian Journal of Thoracic and Cardiovascular Surgery》2023,39(1):37
This report highlights the outcome of valve replacement using TTK Chitra heart mechanical valve in a subgroup of pediatric patients This cohort of 27 pediatric patients with implantations during January 2006 to December 2018 was followed up prospectively. The cohort consisted of 12 aortic valve replacement (AVR), 14 mitral valve replacement (MVR), and 1 double valve replacement (DVR) patients. Total follow-up was 254 patient-years (AVR = 107, MVR = 136, DVR = 11) being 90% complete. The results show that the survival rates and event-free rates were satisfactory. Despite many reservations due to the high risk involved, the long-term benefits of having a durable valve replacement seem to outweigh the risks and offer acceptable long-term survival. 相似文献
30.
Chawla R Arora R Singh S Sagar RK Sharma RK Kumar R Sharma A Tripathi RP Puri SC Khan HA Shawl AS Sultan P Krishan T Qazi GN 《Evidence-based complementary and alternative medicine : eCAM》2006,3(4):503-511
We have evaluated the effect of variation in aryl-tetralin lignans on the radioprotective properties of Podophyllum hexandrum. Two fractionated fractions of P. hexandrum [methanolic (S1) and chloroform fractions (S2)], with varying aryl-tetralin lignan content were utilized for the present study. The peroxyl ion scavenging potentials of S1 and S2 were found to be comparable [i.e. 45.88% (S1) and 41% (S2)] after a 48 h interval in a time-dependent study, whereas in a 2 h study, S2 exhibited significant (P < 0.05) antioxidant activity in different metal ion + flux states. In the aqueous phase, S2 exhibited non-site-specific reactive oxygen species scavenging activity, i.e. 73.12% inhibition at 500 mug ml(-1). S1 exhibited 58.40 +/- 0.8% inhibition (at 0.025 mug ml(-1)) of the formation of reactive nitrite radicals, comparable to S2 (52.45 +/- 0.825%), and also showed 45.01% site-specific activity (1000 mug ml(-1)), along with significant (P < 0.05) electron donation potential (50-2000 mug ml(-1)) compared to S2. Such activities of S1 could be attributed to the significantly (P < 0.05) higher levels of podophyllotoxin beta-d-glucopyranoside (16.5 times) and demethyl podophyllotoxin glucoside (2.9 times) compared with S2. Together, these findings clearly prove that aryl-tetralin lignan content influences the radiation protective potential of the Podophyllum fractions to a great extent. 相似文献