全文获取类型
收费全文 | 1777篇 |
免费 | 86篇 |
国内免费 | 23篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 59篇 |
妇产科学 | 18篇 |
基础医学 | 180篇 |
口腔科学 | 12篇 |
临床医学 | 154篇 |
内科学 | 494篇 |
皮肤病学 | 9篇 |
神经病学 | 61篇 |
特种医学 | 374篇 |
外科学 | 260篇 |
综合类 | 23篇 |
一般理论 | 2篇 |
预防医学 | 93篇 |
眼科学 | 3篇 |
药学 | 69篇 |
中国医学 | 1篇 |
肿瘤学 | 71篇 |
出版年
2021年 | 13篇 |
2020年 | 10篇 |
2019年 | 9篇 |
2018年 | 13篇 |
2015年 | 20篇 |
2014年 | 18篇 |
2013年 | 25篇 |
2012年 | 40篇 |
2011年 | 46篇 |
2010年 | 33篇 |
2009年 | 34篇 |
2008年 | 40篇 |
2007年 | 40篇 |
2006年 | 55篇 |
2005年 | 62篇 |
2004年 | 41篇 |
2003年 | 54篇 |
2002年 | 45篇 |
2001年 | 31篇 |
2000年 | 42篇 |
1999年 | 48篇 |
1998年 | 60篇 |
1997年 | 57篇 |
1996年 | 69篇 |
1995年 | 54篇 |
1994年 | 41篇 |
1993年 | 43篇 |
1992年 | 31篇 |
1991年 | 37篇 |
1990年 | 35篇 |
1989年 | 64篇 |
1988年 | 72篇 |
1987年 | 56篇 |
1986年 | 70篇 |
1985年 | 77篇 |
1984年 | 46篇 |
1983年 | 35篇 |
1982年 | 36篇 |
1981年 | 33篇 |
1980年 | 20篇 |
1979年 | 22篇 |
1978年 | 22篇 |
1977年 | 32篇 |
1976年 | 24篇 |
1975年 | 29篇 |
1974年 | 8篇 |
1973年 | 10篇 |
1972年 | 9篇 |
1970年 | 11篇 |
1968年 | 9篇 |
排序方式: 共有1886条查询结果,搜索用时 15 毫秒
81.
Roberts RO Jacobson DJ Girman CJ Rhodes T Lieber MM Jacobsen SJ 《The Journal of urology》2002,168(6):2467-2471
PURPOSE: We describe a community based study to estimate the prevalence of prostatitis-like symptoms using questions similar to the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI). MATERIALS AND METHODS: Study subjects were a randomly selected sample of Olmsted County, Minnesota white men 40 to 79 years old in January 1990 who participated in a longitudinal study of lower urinary tract symptoms. Subjects were evaluated biennially using self-administered questionnaires. In 2000 questions similar to the NIH-CPSI were incorporated into the questionnaire and questionnaire responses were used to categorize men as having prostatitis-like symptoms. RESULTS: Of 1,541 men 182 (12%) had at least 1 urogenital pain symptom. Pubic (76 men, 4.9%) and testicular (73, 4.7%) pain were the most frequent pain symptoms. A total of 34 men with prostatitis-like symptoms (2.2%) had higher mean pain (6.7 versus 0.5), urinary symptom (3.5 versus 2.1) and quality of life impact (3.7 versus 1.9) scores compared to men who did not (all p <0.001). Pain frequency (OR 39.2, 95% CI 18.8, 81.9) and pain intensity (OR 21.5, 95% CI 8.7, 52.9) were more strongly associated with prostatitis-like symptoms than urinary symptom score (OR 2.8, 95% CI 1.4, 5.6) or quality of life impact score (OR 4.5, 95% CI 1.9, 10.7). CONCLUSIONS: Although urogenital pain is common among community dwelling men, prostatitis-like symptoms based on the modified questions from the NIH-CPSI are less common. While pain measures may be useful in distinguishing between men with and without prostatitis-like symptoms, the urinary symptom and quality of life impact scores could partly reflect benign prostatic hyperplasia. 相似文献
82.
In clinical research, a novel approach has emerged: some of the essential nutrients are being used to treat pathologic conditions. Many of these nutrients, including methionine, must first be activated in the liver or in other tissues before they can exert their key functions. However, this activating process is impaired in disease states and, as a consequence, nutritional requirements change. For instance, for methionine to act as the main cellular methyl donor, it must first be activated to S-adenosylmethionine (SAMe; also known as ademethionine). SAMe is required and is of fundamental importance for the metabolism of nucleic acids and polyamines, the structure and function of membranes, and as a precursor of glutathione. These processes are often seriously altered in various pathologic states addressed in this symposium, but they cannot be restored by simply administering methionine. For instance, in liver disease associated with impairment of the enzyme that activates methionine to SAMe, supplementation with methionine is useless and may even become toxic as it accumulates because it is not used. Accordingly, one must correct the lack of SAMe by bypassing the deficiency in enzyme activation; this is done by providing the product of the defective reaction, namely SAMe. Under these pathologic conditions, SAMe becomes crucial for the functioning of the cell. Thus SAMe, which is found in all living organisms, becomes the essential nutrient instead of methionine. This symposium reviewed the biological and corresponding molecular aspects of SAMe metabolism and the clinical consequences of its deficiency or supplementation in various tissues. 相似文献
83.
Ponomarenko Y Leo MA Kroll W Lieber CS 《Alcohol and alcoholism (Oxford, Oxfordshire)》2002,37(3):252-255
A number of circulating breakdown products of collagen or other components of extracellular matrix, matrix degrading metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) have been proposed as markers of hepatic fibrosis. However, the published results lack consistency. Since many of the patients with fibrosis studied were alcoholics, the question was raised whether recent alcohol consumption may affect the results obtained. Using sandwich-type assays of radioimmunoassay technology with corresponding antibodies, we studied eight markers of liver fibrosis: laminin, tenascin, undulin, TIMP-1, collagen VI, procollagen type III (PIIINP), hyaluronic acid (HA) and MMP-2. A group of 10 alcoholics was studied after significant alcohol consumption and following 2 weeks of abstinence, verified with repeated breath alcohol measurement. Laminin was significantly reduced at 1 week (22%) and at 2 weeks (30%). Similarly, tenascin and undulin were also significantly decreased. By contrast, TIMP-1, collagen VI, PIIINP, HA and MMP-2 did not significantly change. The mode of action of alcohol on these tests is unknown. These differences must be considered when using those measurements to assess liver fibrosis. 相似文献
84.
Endovascular stenting of aneurysms offers potential advantages over surgical clipping. Stenting is minimally invasive, and with the implementation of rapidly developing micro and nano technologies, it will in the future be possible to deploy stents in more remote locations of the cerebrovasculature. The key advantage of stenting is that in addition to impeding flow into the aneurysm, it provides the parent artery with a scaffold over which the artery can remodel. However, for a stent to be effective in this goal, it must be tailored to the local hemodynamics at the aneurysm site. This paper is a review of the qualitative and quantitative in vitro and in vivo experimentation as well as computer simulations that have been performed to elucidate the effects of various stent design parameters and the prevailing parent vessel hemodynamics on intra-aneurysmal flow patterns. Our results in numerous studies have shown that stenting substantially alters intra-aneurysmal flow. Furthermore, it is demonstrated that techniques have been developed in order to assess the efficacy of the stent in promoting intra-aneurysmal flow stagnation, thus creating the potential to optimize the device design for the treatment of intracranial aneurysms. 相似文献
85.
Effect of glacial acetic acid and ethiodized oil concentration on embolization with N-butyl 2-cyanoacrylate: an in vivo investigation 总被引:4,自引:0,他引:4
Gounis MJ Lieber BB Wakhloo AK Siekmann R Hopkins LN 《AJNR. American journal of neuroradiology》2002,23(6):938-944
BACKGROUND AND PURPOSE: Precise control of the polymerization dynamics of cyanoacrylate mixtures used in the embolization of cerebral arteriovenous malformations is required to achieve a safe and permanent obliteration of the lesion. In this study, in vivo embolization using mixtures of Histoacryl, Lipiodol Ultra-Fluid, and glacial acetic acid (GAA) was investigated. The present study investigated whether increased ethiodized oil concentration or the addition of GAA increased rate of embolization. METHODS: Using embolic mixtures containing Histoacryl (N-butyl 2-cyanoacrylate [NBCA]), the embolization process in the femoral and subclavian arteries of the rabbit was examined. Various embolic agents composed of ethiodized oil and N-BCA mixtures, either with or without the addition of minute quantities of GAA, were injected. Blood flow through the aforementioned arteries was measured during embolization. The transient decay of blood flow to zero was modeled, and an optimized model parameter, termed the time elapsed to flow arrest (TEFA) factor, was compared with the experimental data related to the embolization process. RESULTS: The TEFA factor was independent of the variation of the ethiodized oil concentration in the mixture (P >.05). In contradistinction, the addition of GAA significantly increased the TEFA factor (P <.05). Moreover, a linear relation between the TEFA factor and the quantity of GAA in the mixture was discerned. CONCLUSION: Predictable control of the embolization process with N-BCA in vivo is attained by varying the amount of GAA in the embolic mixture. 相似文献
86.
87.
88.
Anatomic and biomechanical properties of the passive brachioradialis muscle were investigated to understand the limited excursion of this muscle seen during tendon transfer surgery. First, architectural measurements were performed on three fiber bundles obtained from four regions of the brachioradialis (10 specimens) chosen to represent the range of muscle fiber lengths across the brachioradialis. Next, in separate specimens (eight specimens), passive excursion was measured by securing the distal tendon stump to a servomotor. A constant load of 4.9 N was applied to the tendon, while the distal tendon was released from the surrounding tissue in 3-cm increments. Within the four regions studied, muscle fiber length varied significantly from 104.2 +/- 6.2 mm to 179.8 +/- 6.1 mm. As the brachioradialis was released, an average of 3 mm of mobility was obtained for each interval whereas for the succeeding three intervals, an average of 5.3 mm of mobility was obtained. This resulted in 22.2 +/- 2.3 mm of mobility when each specimen was fully released. These data show that there is no intrinsic muscle fiber length limitation to excursion, but that excursion is limited by other intermuscular connections to adjacent connective tissue and other muscles. 相似文献
89.
90.