全文获取类型
收费全文 | 39266篇 |
免费 | 3979篇 |
国内免费 | 1322篇 |
专业分类
耳鼻咽喉 | 176篇 |
儿科学 | 2005篇 |
妇产科学 | 778篇 |
基础医学 | 3569篇 |
口腔科学 | 797篇 |
临床医学 | 4670篇 |
内科学 | 6828篇 |
皮肤病学 | 255篇 |
神经病学 | 2004篇 |
特种医学 | 1450篇 |
外国民族医学 | 9篇 |
外科学 | 5583篇 |
综合类 | 5240篇 |
现状与发展 | 4篇 |
一般理论 | 1篇 |
预防医学 | 4142篇 |
眼科学 | 1007篇 |
药学 | 3262篇 |
13篇 | |
中国医学 | 1254篇 |
肿瘤学 | 1520篇 |
出版年
2024年 | 89篇 |
2023年 | 637篇 |
2022年 | 1326篇 |
2021年 | 1612篇 |
2020年 | 1498篇 |
2019年 | 1477篇 |
2018年 | 1443篇 |
2017年 | 1330篇 |
2016年 | 1316篇 |
2015年 | 1291篇 |
2014年 | 2386篇 |
2013年 | 3044篇 |
2012年 | 2096篇 |
2011年 | 2295篇 |
2010年 | 1881篇 |
2009年 | 1841篇 |
2008年 | 1954篇 |
2007年 | 1925篇 |
2006年 | 1739篇 |
2005年 | 1674篇 |
2004年 | 1463篇 |
2003年 | 1284篇 |
2002年 | 1061篇 |
2001年 | 947篇 |
2000年 | 848篇 |
1999年 | 675篇 |
1998年 | 595篇 |
1997年 | 623篇 |
1996年 | 514篇 |
1995年 | 418篇 |
1994年 | 402篇 |
1993年 | 332篇 |
1992年 | 296篇 |
1991年 | 259篇 |
1990年 | 207篇 |
1989年 | 187篇 |
1988年 | 176篇 |
1987年 | 158篇 |
1986年 | 119篇 |
1985年 | 187篇 |
1984年 | 163篇 |
1983年 | 132篇 |
1982年 | 130篇 |
1981年 | 126篇 |
1980年 | 108篇 |
1979年 | 62篇 |
1978年 | 52篇 |
1977年 | 50篇 |
1976年 | 41篇 |
1975年 | 31篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
A new range of stand magnifiers has been released by the COIL company in the United Kingdom. Examination of these magnifiers reveals that they fail to deliver the rated magnifications labelled prominently on the appliances, as a result of the manufacturer's conformance with the requirements of the German DIN standard and the use of back vertex power (F'v) rather than equivalent dioptric power (Fm) of the magnifier. In this study we provide information on the optometric parameters of these new stand magnifiers that will assist the more accurate specification of improvements in vision expected from their use. 相似文献
12.
Data on 232 members of a single pedigree, descended from two pairs of original parents, were made available to the participants of Genetic Analysis Workshop 8 (GAW8). In addition to information concerning age and sex, measurements for 10 quantitative traits and genotypes at 22 polymorphic marker loci were also provided for a subset of 193 of these family members. © 1993 Wiley-Liss, Inc. 相似文献
13.
Prevention of Bone Loss by Clodronate in Early Postmenopausal Women with Vertebral Osteopenia: A Dose-Finding Study 总被引:1,自引:0,他引:1
M. J. V?lim?ki K. Laitinen K. Laitinen A. Patronen H. Puolijoki H. Puolijoki J. Sepp?nen L. Pylkk?nenand the Probone Study Group 《Osteoporosis international》2002,13(12):937-947
This double-masked, placebo-controlled study was undertaken to determine the efficacy and safety of oral clodronate in the
prevention of bone loss in early postmenopausal women with vertebral osteopenia. Altogether 610 women with a mean age of 53
years were recruited for the study. They were 1–5 years postmenopausal and their lumbar spine bone mineral density (BMD) was
at least 1 standard deviation below the mean of premenopausal women (T-score ≤−1). The subjects were randomized into five study groups to receive either placebo, clodronate 65 mg, 400 mg or 800
mg daily, or intermittent clodronate in 3 month cycles with 400 mg daily for 15 days followed with no treatment for 75 days
for 3 years. One hundred and eighty-seven of 509 women who completed the primary study continued in the extension study of
2 years in which previous placebo users were switched to clodronate 800 mg daily, while previous users of 400 mg or 800 mg
of clodronate used either placebo or 800 mg of clodronate daily. In the primary study clodronate was administered in the evening,
and in the extension 1 h before breakfast on an empty stomach. In the primary study mean changes in lumbar spine BMD were
−3.4% in the placebo group and +0.4% in 800 mg clodronate group [difference between groups at 3 years 3.8% (95% CI 2.7% to
4.9%, p<0.0001)], and in the trochanter area BMD −1.1% in the placebo group, and + 0.4% in the 800 mg clodronate group [difference
between groups at 3 years 1.5% (95% CI 0.05% to 2.9%)]. During the extension study mean changes in lumbar spine BMD were +1.5%
in the clodronate group and −0.2 % in the placebo group [difference between groups 1.7% (CI 0.4% to 3.0%, p = 0.010)] and in trochanter BMD were +2.5% in the clodronate group and no change in the placebo group [difference between
groups 2.1% (CI 0.3% to 3.9%, p = 0.007)]. No statistically significant differences between the placebo and 800 mg clodronate groups were found in the femoral
neck BMD. In the primary study the urinary excretion of type I collagen aminoterminal telopeptide (NTX) decreased by 44% (p<0.0001 compared with placebo) and that of deoxypyridinoline by 18% (p<0.0001) in the clodronate 800 mg group. In the extension study urinary NTX decreased by 51% (p<0.0001) in those who were switched to 800 mg of clodronate and increased by 67% (p<0.0001) in those who stopped using that dose. There was no difference in the frequency of gastrointestinal complaints between
clodronate- and placebo-treated patients in the primary study, but they were more common among women who received clodronate
in the extension phase. Clodronate in daily doses of 400–800 mg caused a slight elevation of aminotransferase levels, usually
within the reference range. In bone biopsies no defect in mineralization was found. In conclusion, clodronate in a daily dose
of 800 mg prevents early postmenopausal bone loss at the sites of the skeleton in which cancellous bone predominates. It effectively
reduces bone resorption and bone turnover rate. Antifracture efficacy of clodronate remains to be established by prospective,
placebo-controlled trials.
Received: 4 March 2002 / Accepted: 9 July 2002 相似文献
14.
目的 :研究老年人不同疾病时骨密度 (BMD)的分布情况。方法 :用DXADAS 6 0 0EX型骨密度仪对183例老年患者进行左侧远程桡骨加尺骨BMD检测。结果 :内分泌疾病组、消化道疾病组和其它疾病组的患病率分别为 72 7% ,2 0 6 %和 31 4 %。T值比较 :三组差异明显 (P <0 0 0 1)。累积骨丢失率 (ABLR)比较 :前一组明显高于后两组病人 (P <0 0 1)。BMD比较中 ,内分泌和其它疾病组明显低于消化道疾病组 (P <0 0 0 1)。相关分析显示 ,内分泌和消化道疾病组的年龄变化与BMD呈正相关 (r =0 5 19P <0 0 0 1和r =0 5 89P <0 0 0 1) ,内分泌疾病组和其它疾病组的体重变化与BMD呈正相关 (r=0 918P <0 0 0 1和r =0 338P <0 0 0 1)。结论 :老年人骨质疏松 (OP)患病率以内分泌疾病组最高 ,消化道疾病组较低 ;随年龄和体重增加 ,BMD降低加重。 相似文献
15.
C. I. V. FRANKLIN 《Journal of Medical Imaging and Radiation Oncology》1991,35(1):68-71
The records of 108 adult patients with supratentorial low grade astrocytoma presenting between 1/1/80 and 31/12/87 were examined for the following factors which might affect survival: patient age, extent of surgical resection, site of tumour, tumour grade, radiation field size and radiation dose. Univariate analysis showed that patient age, field size and radiation dose were significant prognostic factors, but with multivariate analysis only patient age and radiation field size were significant independent variables. It is possible that field size is a proxy variable for tumour size. 相似文献
16.
Zongli Lin Meir Pachter Siva Banda Yacov Shamash 《Optimal control applications & methods.》2002,23(1):21-43
A design technique (Control of Uncertain Systems with Bounded Inputs, Tarbouriech S, Garcia G, (Eds), Lecture Notes in Control and Information Sciences, vol. 227 , Springer: Berlin, 1997; 173–186) recently proposed for stabilization of a linear system with rate‐limited actuators is utilized to design feedback laws that cause the system output to track a desired command signal. This design technique combines two design techniques recently developed for linear systems with position limited actuators, piecewise‐linear LQ control (Automatica, 1994; 30 : 403–416) and low‐and‐high gain feedback (IEEE Trans. Automat. Control, 1996; 41 : 368–378), and hence takes advantage of both design techniques, while avoiding their disadvantages. In the case that only the output is available for feedback, the performance of the state feedback law is preserved by the use of a fast observer. An open‐loop exponentially unstable fighter aircraft is used to demonstrate the effectiveness of the proposed control design method. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
17.
Yang Hee Kim Young In Moon Young Hee Kang Jung Sook Kang 《Nutrition Research And Practice》2007,1(4):298-304
This study was conducted to investigate the hypocholesterolemic effect of simvastatin (30 mg/kg BW) and antioxidant effect of coenzyme Q10 (CoQ10, 15 mg/kg BW) or green tea (5%) on erythrocyte Na leak, platelet aggregation and TBARS production in hypercholesterolemic rats treated with statin. Food efficiency ratio (FER, ADG/ADFI) was decreased in statin group and increased in green tea group, and the difference between these two groups was significant (p<0.05). Plasma total cholesterol was somewhat increased in all groups with statin compared with control. Plasma triglyceride was decreased in statin group and increased in groups of CoQ10 and green tea, and the difference between groups of statin and green tea was significant (p<0.05). Liver total cholesterol was not different between the control and statin group, but was significantly decreased in the group with green tea compared with other groups (p<0.05). Liver triglyceride was decreased in groups of statin and green tea compared with the control, and the difference between groups of the control and green tea was significant (p<0.05). Platelet aggregation of both the initial slope and the maximum was not significantly different, but the group with green tea tended to be higher in initial slope and lower in the maximum. Intracellular Na of group with green tea was significantly higher than the control or statin group (p<0.05). Na leak in intact cells was significantly decreased in the statin group compared with the control (p<0.05). Na leak in AAPH treated cells was also significantly reduced in the statin group compared with groups of the control and CoQ10 (p<0.05). TBARS production in platelet rich plasma was significantly decreased in the groups with CoQ10 and green tea compared with the control and statin groups (p<0.05). TBARS of liver was significantly decreased in the group with green tea compared with the statin group (p<0.05). In the present study, even a high dose of statin did not show a cholesterol lowering effect, therefore depletion of CoQ10 following statin treatment in rats is not clear. More clinical studies are needed for therapeutic use of CoQ10 as an antioxidant in prevention of degenerative diseases independent of statin therapy. 相似文献
18.
M. P. Gosselink J. J. Busschbach† C. M. Dijkhuis§ L. P. Stassen¶ W. C. Hop‡ W. R. Schouten 《Colorectal disease》2006,8(1):15-22
BACKGROUND: After total mesorectal excision for rectal cancer, many surgeons try to avoid an abdominoperineal resection (APR) by performing a transanally double stapled low colo-rectal anastomosis (LRA), frequently without a pouch. This policy is mainly based on the assumption that the quality of life after such LRA is higher than after APR. It has been suggested that a better functional outcome and therefore a higher quality of life might be achieved by a colo-anal J-pouch anastomosis (CPA). The aim of this study was to assess quality of life among disease-free survivors after APR, LRA and CPA. METHODS: The charts of 301 consecutive patients who had undergone surgery for cancer in the middle or lower third of the rectum were analysed. Two hundred four patients were eligible for inclusion. The quality of life among these patients was assessed using one generic (EQ-5D) and two disease-specific questionnaires (EORTC QLQ-C30 and EORTC QLQ-CR38). RESULTS: The response rate was 82%. The median follow-up was 31 months. Overall, quality of life was good but CPA patients had better quality of life scores than APR and LRA patients. This difference was not only due to the better functional outcome but also to the lower incidence of disturbed micturition and sexual problems in the CPA group. CONCLUSION: The quality of life after colo-anal J-pouch anastomosis is better than after abdominoperineal resection (APR) and low colo-rectal anastomosis (LRA). The quality of life after APR is similar to that after LRA. 相似文献
19.
Henry Ho‐Lung Chan 《Clinical & experimental optometry》2005,88(6):410-414
The first‐order kernel analysis in multifocal electroretinogram (mfERG) using low contrast stimulation is suggested as a way to detect the inner retinal responses in animal studies. In this case report, this protocol is applied to human patients with glaucoma to demonstrate the possibility of using mfERG as a tool to detect glaucomatous damage. Two patients with glaucoma were recruited and had mfERG measurements with the 103‐scaled hexagonal stimulus pattern at low (50 per cent) contrast. Their responses were analysed and compared with those from normal subjects with the mfERG measured under the same condition. In the normal subjects, there were obvious oscillatory components on the ascending and descending limbs of the first‐order kernel response to 50 per cent contrast. In the glaucomatous patients, the oscillatory component on the descending limb was obviously diminished. In addition, this component was significantly diminished in the quadrant with a glaucomatous visual field defect. This suggests that the low‐contrast stimulation condition in mERG measurement may provide a good way to detect glaucomatous damage and this may help in clinical diagnosis of glaucoma. 相似文献
20.