全文获取类型
收费全文 | 3277篇 |
免费 | 208篇 |
国内免费 | 3篇 |
专业分类
耳鼻咽喉 | 19篇 |
儿科学 | 71篇 |
妇产科学 | 105篇 |
基础医学 | 473篇 |
口腔科学 | 55篇 |
临床医学 | 352篇 |
内科学 | 945篇 |
皮肤病学 | 35篇 |
神经病学 | 182篇 |
特种医学 | 149篇 |
外科学 | 539篇 |
综合类 | 25篇 |
预防医学 | 165篇 |
眼科学 | 53篇 |
药学 | 155篇 |
中国医学 | 1篇 |
肿瘤学 | 164篇 |
出版年
2021年 | 36篇 |
2020年 | 32篇 |
2019年 | 47篇 |
2018年 | 77篇 |
2017年 | 42篇 |
2016年 | 55篇 |
2015年 | 58篇 |
2014年 | 59篇 |
2013年 | 122篇 |
2012年 | 140篇 |
2011年 | 157篇 |
2010年 | 84篇 |
2009年 | 87篇 |
2008年 | 144篇 |
2007年 | 139篇 |
2006年 | 144篇 |
2005年 | 111篇 |
2004年 | 127篇 |
2003年 | 114篇 |
2002年 | 112篇 |
2001年 | 103篇 |
2000年 | 129篇 |
1999年 | 109篇 |
1998年 | 34篇 |
1997年 | 26篇 |
1996年 | 36篇 |
1995年 | 30篇 |
1994年 | 29篇 |
1993年 | 29篇 |
1992年 | 75篇 |
1991年 | 70篇 |
1990年 | 83篇 |
1989年 | 79篇 |
1988年 | 73篇 |
1987年 | 74篇 |
1986年 | 65篇 |
1985年 | 46篇 |
1984年 | 55篇 |
1983年 | 48篇 |
1982年 | 26篇 |
1981年 | 31篇 |
1980年 | 22篇 |
1979年 | 33篇 |
1978年 | 21篇 |
1977年 | 22篇 |
1976年 | 21篇 |
1975年 | 30篇 |
1974年 | 36篇 |
1973年 | 34篇 |
1970年 | 20篇 |
排序方式: 共有3488条查询结果,搜索用时 0 毫秒
1.
K Thomsen B J Riis J S Johansen C Christiansen P R?dbro 《Gynecological endocrinology》1987,1(2):169-175
Bone turnover before and after withdrawal of estrogen/gestagen treatment was studied in a randomized trial with 110 healthy female volunteers, who had passed a natural menopause 6 months to 3 years before the start of the study. Urinary excretion of intravenously injected 99m-technetium diphosphonate was measured as an index of bone turnover; plasma bone Gla protein and serum alkaline phosphatase were measured as indices of bone formation; and fasting urinary excretion of hydroxyproline and calcium were measured as estimates of bone resorption. During 2 years of hormone treatment, all variables decreased highly significantly (p less than 0.001) to a constant low level. Three months after withdrawal all variables increased highly significantly (p less than 0.001) towards, but not above, pretreatment and placebo levels. We conclude that withdrawal of estrogen/gestagen replacement therapy in postmenopausal women increases bone turnover, but not in excess of pretreatment values. This indicates that bone loss (after withdrawal) is similar to that seen in the placebo group and that a rebound phenomenon is unlikely. 相似文献
2.
3.
Jens O L J?rgensen Louise M?ller Morten Krag Nils Billestrup Jens S Christiansen 《Endocrinology & Metabolism Clinics of North America》2007,36(1):75-87
This article focuses on in vivo data from tests performed in normal subjects and in patients who had abnormal growth hormone (GH) status. Experimental data in human subjects demonstrate that GH acutely inhibits glucose disposal in skeletal muscle. At the same time GH stimulates the turnover and oxidation of free fatty acid (FFA), and experimental evidence suggests a causal link between elevated FFA levels and insulin resistance in skeletal muscle. Observational data in GH-deficient adults do not indicate that GH replacement is associated with significant impairment of glucose tolerance, but it is recommended that overdosing be avoided and glycemic control be monitored. 相似文献
4.
PURPOSE: Currently, no drug treatment is available for strengthening underacting extraocular muscles (EOM) in strabismus. We showed previously that single injections of insulin-like growth factor (IGF-1) result in significant but short-term increases in muscle force generation. This study examined the effects of sustained release of IGF-1 on force generation in rabbit superior rectus muscles. METHODS: In adult rabbits, slow-release pellets containing IGF-1 were implanted on the global side of one superior rectus muscle. After 1 week, or 1, 2, 3, or 6 months, treated and control muscles were examined for force generation using an in vitro physiology apparatus. All muscles were prepared for histology and mean myofiber cross-sectional areas were determined. RESULTS: One and 3 months after pellet implantation, treated muscles generated significantly greater force than contralateral control muscles, whereas at 2 months, no significant difference was found. Force per cross-sectional area (mN/cm(2)) at 3 months also increased significantly in the treated muscles. Mean muscle cross-sectional area increased significantly after 1, 2, and 3 months of sustained exposure to IGF-1 compared with controls. After an additional 3 months without IGF-1 exposure, mean cross-sectional areas were significantly greater than controls but significantly reduced compared with areas at 1, 2, and 3 months. CONCLUSIONS: IGF-1 appears to be highly effective in increasing muscle force generation. Because slow release of IGF-1 results in sustained increases in EOM force generation, it may be a potentially useful alternative to surgical resection procedures because it avoids many of the potential long-term biomechanical hazards of resection surgery. 相似文献
5.
6.
Morten A Karsdal Thomas J Martin Jens Bollerslev Claus Christiansen Kim Henriksen 《Journal of bone and mineral research》2007,22(4):487-494
Some osteopetrotic mutations lead to low resorption, increased numbers of osteoclasts, and increased bone formation, whereas other osteopetrotic mutations lead to low resorption, low numbers of osteoclasts, and decreased bone formation. Elaborating on these findings, we discuss the possibility that osteoclasts are the source of anabolic signals for osteoblasts. In normal healthy individuals, bone formation is coupled to bone resorption in a tight equilibrium. When this delicate balance is disturbed, the net result is pathological situations, such as osteopetrosis or osteoporosis. Human osteopetrosis, caused by mutations in proteins involved in the acidification of the resorption lacuna (ClC-7 or the a3-V-ATPase), is characterized by decreased resorption in face of normal or even increased bone formation. Mouse mutations leading to ablation of osteoclasts (e.g., loss of macrophage-colony stimulating factor [M-CSF] or c-fos) lead to secondary negative effects on bone formation, in contrast to mutations where bone resorption is abrogated with sustained osteoclast numbers, such as the c-src mice. These data indicate a central role for osteoclasts, and not necessarily their resorptive activity, in the control of bone formation. In this review, we consider the balance between bone resorption and bone formation, reviewing novel data that have shown that this principle is more complex than originally thought. We highlight the distinct possibility that osteoclast function can be divided into two more or less separate functions, namely bone resorption and stimulation of bone formation. Finally, we describe the likely possibility that bone resorption can be attenuated pharmacologically without the undesirable reduction in bone formation. 相似文献
7.
Anal sphincter size measured by endosonography in healthy volunteers. Effect of age, sex, and parity. 总被引:8,自引:0,他引:8
M B Nielsen C Hauge O O Rasmussen M S?rensen J F Pedersen J Christiansen 《Acta radiologica (Stockholm, Sweden : 1987)》1992,33(5):453-456
The anal sphincter muscles consist of the circular internal and external sphincters together with the sling-shaped associated puborectalis muscle. Ten men, 10 women with no vaginal deliveries, and 10 women with one or more vaginal deliveries were studied with anal endosonography using a 7 MHz multiplanar endoprobe. The thickness of the internal sphincter and the thickness, length, and cross-sectional area of the external sphincter were measured and related to age, sex, and parity. Reproducibility was assessed by similar measurements on different days in 10 volunteers. Anal sphincter size was the same in men and women and was not affected by the number of child births. Internal sphincter muscle thickness increased with age. Anal manometry and electromyography with an anal sponge were performed in all volunteers but the results did not correlate to any of the anal sphincter dimensions. Our conclusion is that although there are some limitations, endosonography can be used to determine the size of the anal sphincter muscles. 相似文献
8.
9.
Amplification or duplication of the AML1 gene at chromosome band 21q22 was detected by FISH using a locus-specific probe in three out of 171 unselected patients with therapy-related myelodysplasia (t-MDS) or t-AML (1.7%). In two patients AML1 signals were located tandemly on derivative chromosomes, in one patient on a dic(9;21) and in the the other patient on a derivative chromosome 18 made up of interchanging layers of material from chromosomes 9, 14, 18, and 21. In the third patient three single supernumerary copies of AML1 were located on derivatives of chromosomes 19 and 21. All three patients were older, had previously received therapy with alkylating agents without topoisomerase II inhibitors, had complex karyotypes including abnormalities of chromosomes 5 or 7, and presented acquired point mutations of the TP53 gene. No point mutations of the AML1 gene were observed. The results support a pivotal role of impaired TP53 function in the development of gene amplification or duplication in t-MDS and t-AML. 相似文献
10.
O L Svendsen U Marslew C Hassager C Christiansen 《European journal of nuclear medicine》1992,19(1):41-46
Two dual energy X-ray absorptiometric (DXA) instruments have recently become commercially available for local bone densitometry: the QDR-1000 (Hologic Inc.) and the DPX (Lunar Radiation Corp.). We report the precision, influence of femoral rotation, correlation and agreement of bone mineral measurements of the proximal femur by these two instruments. In vitro (femur phantom) short-term precision was 1.1%-3.5%, and the long-term precision was 1.2%-3.8%. In vivo (groups of 10 premenopausal and 10 post-menopausal women) short-term precision of duplicate measurements was 1.6%-4.7%, and long-term precision was 1.9%-5.5%. Overall, the precision for Ward's triangle was over 3% and that for the femoral neck and trochanter, 2%-3%. Rotation of a femur phantom produced a statistically significant change in the bone mineral density (BMD) of the femoral neck. Within a clinically relevant range of femoral rotation (20 degrees inward rotation +/- 5 degrees) the coefficient of variation (CV%) increased by a mean factor of 1.1-1.4. Although the correlation (r less than 0.9) between BMD measurements of the proximal femur by the DPX and QDR-1000 in 30 postmenopausal women was high, there was lack of agreement between the two instruments. We found no statistically significant differences between the right and left femur in 30 postmenopausal women. A bilateral femur scan took a mean total time of about 22 min. We conclude that with the introduction of DXA instruments, the precision of bone mineral measurements of the proximal femur has improved. However, for comparability between commercially available DXA instruments, it might be advantageous if units were standardized. 相似文献