全文获取类型
收费全文 | 122362篇 |
免费 | 10415篇 |
国内免费 | 5770篇 |
专业分类
耳鼻咽喉 | 872篇 |
儿科学 | 4161篇 |
妇产科学 | 2932篇 |
基础医学 | 14601篇 |
口腔科学 | 3067篇 |
临床医学 | 11337篇 |
内科学 | 19136篇 |
皮肤病学 | 1778篇 |
神经病学 | 9075篇 |
特种医学 | 2320篇 |
外国民族医学 | 36篇 |
外科学 | 10146篇 |
综合类 | 19663篇 |
现状与发展 | 19篇 |
预防医学 | 10579篇 |
眼科学 | 3285篇 |
药学 | 11348篇 |
39篇 | |
中国医学 | 4255篇 |
肿瘤学 | 9898篇 |
出版年
2024年 | 322篇 |
2023年 | 1483篇 |
2022年 | 3282篇 |
2021年 | 4314篇 |
2020年 | 3784篇 |
2019年 | 3529篇 |
2018年 | 3413篇 |
2017年 | 3945篇 |
2016年 | 4204篇 |
2015年 | 4269篇 |
2014年 | 7393篇 |
2013年 | 8583篇 |
2012年 | 7464篇 |
2011年 | 8380篇 |
2010年 | 7010篇 |
2009年 | 6650篇 |
2008年 | 6901篇 |
2007年 | 6985篇 |
2006年 | 6258篇 |
2005年 | 5619篇 |
2004年 | 4706篇 |
2003年 | 4108篇 |
2002年 | 3452篇 |
2001年 | 3026篇 |
2000年 | 2583篇 |
1999年 | 2187篇 |
1998年 | 1889篇 |
1997年 | 1673篇 |
1996年 | 1545篇 |
1995年 | 1368篇 |
1994年 | 1179篇 |
1993年 | 959篇 |
1992年 | 855篇 |
1991年 | 701篇 |
1990年 | 659篇 |
1989年 | 509篇 |
1988年 | 387篇 |
1987年 | 345篇 |
1986年 | 302篇 |
1985年 | 436篇 |
1984年 | 349篇 |
1983年 | 237篇 |
1982年 | 328篇 |
1981年 | 206篇 |
1980年 | 182篇 |
1979年 | 125篇 |
1978年 | 106篇 |
1977年 | 87篇 |
1976年 | 80篇 |
1975年 | 55篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
Abstract: The effects of pyridoxalated hemoglobin polyoxyethylene conjugate (PHP) and stroma-free hemoglobin (SFH) on vascular responsiveness to various vasoactive substances were examined in isolated perfused rat kidneys. The kidneys isolated from rats were perfused with 6% PHP, 6% SFH, and 6% hydroxyethylstarch (HES) solution at a constant flow rate. Vascular responsiveness to acetylcholine (ACh), nitroglycerin (NG), norepinephrine (NE), and angiotensin-II (ANG-II) was examined by measuring the perfusion pressure (PP). Effects of inhibition of endothelium-derived relaxing factor (EDRF) by NG -monomethyl L-arginine (L-NMMA) on NE-induced and ANG-II-induced renal vascular responses were examined. ACh and NG induced a dose-dependent decrease in perfusion pressure (PP) in all groups. NE and ANG-II induced an increase in PP in all groups, but NE-induced and ANG-II-induced responses in the PHP-perfused and SFH-perfused groups were significantly larger than those in the HES-perfused group. L-NMMA did not alter vascular responsiveness to NE and ANG-II. These results indicate that PHP and SFH do not inhibit EDRF induced by ACh, but hemoglobin moiety per se does augment the vascular responsiveness to NE and ANG-II in the isolated perfused rat kidney. 相似文献
92.
Association of Vascular Endothelial Growth Factor Expression with Tumor Angiogenesis and with Early Relapse in Primary Breast Cancer 总被引:10,自引:0,他引:10
Masakazu Toi Seigo Hoshina Toshiaki Takayanagi Takeshi Tominaga 《Cancer science》1994,85(10):1045-1049
Angiogenesis is an independent prognostic indicator in breast cancer. In this report, the relationship between expression of vascular endothclial growth factor (VEGF; a selective mitogen for endothelial cells) and the microvessel density was examined in 103 primary breast cancers. The expression of VEGF was evaluated by immunocytochemical staining using anti-VEGF antibody. The microvessel density, which was determined by immunostaining for factor VIII antigen, in VEGF-rich tumors was clearly higher than that in VEGF-poor tumors ( P <0.01). There was a good correlation between VEGF expression and the increment of microvessel density. Furthermore, postoperative survey demonstrated that the relapse-free survival rate of VEGF-rich tumors was significantly worse than that of VEGF-poor tumors. It was suggested that the expression of VEGF is closely associated with the promotion of angiogenesis and with early relapse in primary breast cancer. 相似文献
93.
我国较贫困地区农村学龄前儿童膳食状况 总被引:5,自引:0,他引:5
对1985~1989年7省较贫困的18个乡农村儿童膳食调查资料采用平均摄入量、临界值及概率法进行了总结分析。结果表明,6~24月龄母乳喂养儿的辅食品种单一,数量不足。断奶儿童各年龄组热能、蛋白质摄入量的平均值分别达RDA的92%~104%和76%~84%,但以RDA为界值,仍有53%~62%及74%~85%的儿童热能、蛋白质摄入量低,用概率法分析蛋白质、钙、维生素A、B2、C及铁摄入不足的人数比例分别是50%~60%、93%~97%、51%~87%、74%~86%、58%~66%和12%~47%。热能、蛋白质摄入量低于RDA值儿童的身高、体重明显低于摄入量高于RDA值的儿童。 相似文献
94.
The growth and development of vegan children 总被引:1,自引:0,他引:1
The results of prospective study on the growth and diets, estimated from 7-day weighed food intake records, of 20 life vegan children (aged 5.8–12.8 years) are presented. The growth and development of the children were normal but they tended to be lighter in weight and exceptionally lean compared with standards. Heights were around the median of the Tanner-Whitehouse standards but were lower than the medians recently proposed by the Department of Health. Energy intakes were similar to those reported in children of the same age in the general population, but dietary fibre intakes were very high which may have influenced the digestible energy. Sugar provided an average 15.6% of the dietary energy and this was supplied mainly by fruit and fruit juice. Mean fat intakes were close to the dietary reference values. Daily intakes of essential nutrients generally met the amounts recommended, with the exceptions of calcium and vitamin B12 . Many children received supplementary sources of vitamin B12 and only two children had intakes below the lower recommended nutrient intake. Intakes of saturated fatty acids were low and those of linoleic acid were high. The ratio of linoleic/α-linolenic acid was high. As docosahexaenoic acid is absent from vegan diets, it is suggested that vegans should use oils with a lower ratio of linoleic/α-linolenic acid. Future studies should also consider the influence of a vegan diet on retinal function. None of the children was immunized against whooping cough and 11 had not been immunized against polio: 16 of the children had suffered from whooping cough. Future studies need to take into account factors other than diet when assessing the health of vegans. The results of this study show that children can be successfully reared on a vegan diet providing sufficient care is taken to avoid the known pitfalls of a bulky diet and vitamin B12 deficiency. 相似文献
95.
96.
Anthropometric data on 110 myelomeningocele (MMC) subjects in relation to age, sex, level of lesion and ambulation were studied to investigate growth and the occurrence of obesity in MMC. In 52 subjects, indices of obesity were validated against body composition analysis of total body fat (%BF) using body potassium and body water techniques. Most subjects were short and light compared to reference data and became relatively shorter and heavier with age. Overall trunk growth was not affected by the level of lesion, but sitting height was affected by kyphoscoliosis. Arm spans were similar to reference data, but were significantly greater in wheelchair users. Leg length was greatest in those who walked. Body composition data showed excess adipose in many MMC subjects, this tendency increasing with age. When correlated with %BF determined from body composition analysis, common clinical indices of obesity had variable r values (wt/ht2 0.78; wt/sitting ht2 0.77; upper arm fat area 0.75; triceps skinfold 0.74; wt/arm span2 0.68, with the 4 skinfold method correlating best, 0.82). Anthropometric measures, taken with cognizance of level of disability and mobility, can accurately assess body growth and the occurrence of obesity in MMC. The influence of ambulatory activity in promoting normal growth is emphasized. 相似文献
97.
KILL AND CURE THE HOPE AND REALITY OF VIRUS INACTIVATION 总被引:2,自引:0,他引:2
CHRISTOPHER PROWSE 《Vox sanguinis》1994,67(S3):191-196
98.
99.
G. J. Breur M. D. Lapierre K. Kazmierczak K. M. Stechuchak G. P. McCabe 《Calcified tissue international》1997,61(5):418-425
In this study, we tested the hypotheses that (a) both the domain volume (volume of the cell and the matrix it has formed)
and matrix volume of juxtametaphyseal hypertrophic chondrocytes in the growth plate is tightly controlled, and that (b) the
domain volume of juxtametaphyseal hypertrophic chondrocytes is a strong determinant of the rate of bone length growth. We
analyzed the rate of bone length growth (oxytetracycline labeling techniques) and nine stereologic and kinetic parameters
related to the juxtametaphyseal chondrocytic domain in the proximal and distal radial and tibial growth plates of 21- and
35-day-old rats. The domain volume increased with increasing growth rates, independent of the location of the growth plate
and the age of the animal. Within age groups, the matrix volume per cell increased with increasing growth rates, but an identical
growth plate had the same matrix volume per cell in 21- and 35-day-old rats. The most suitable regression model (R
2= 0.992) to describe the rate of bone length growth included the mean volume of juxtametaphyseal hypertrophic chondrocytes
and the mean rate of cell loss/cell proliferation. This relationship was independent of the location of the growth plate and
the age of the animal. The data suggest that the domain volume of juxtametaphyseal hypertrophic chondrocytes, as well as the
matrix volume produced per cell, may be tightly regulated. In addition, the volume of juxtametaphyseal hypertrophic chondrocytes
and the rate of cell loss/rate of cell proliferation may play the most important role in the determination of the rate of
bone length growth.
Received: 2 December 1996 / Accepted: 24 March 1997 相似文献
100.