全文获取类型
收费全文 | 52568篇 |
免费 | 4515篇 |
国内免费 | 239篇 |
专业分类
耳鼻咽喉 | 653篇 |
儿科学 | 1678篇 |
妇产科学 | 1407篇 |
基础医学 | 7173篇 |
口腔科学 | 967篇 |
临床医学 | 5049篇 |
内科学 | 10541篇 |
皮肤病学 | 771篇 |
神经病学 | 4075篇 |
特种医学 | 1680篇 |
外国民族医学 | 10篇 |
外科学 | 6726篇 |
综合类 | 1211篇 |
一般理论 | 51篇 |
预防医学 | 6871篇 |
眼科学 | 1309篇 |
药学 | 3462篇 |
2篇 | |
中国医学 | 173篇 |
肿瘤学 | 3513篇 |
出版年
2023年 | 321篇 |
2022年 | 552篇 |
2021年 | 1066篇 |
2020年 | 531篇 |
2019年 | 968篇 |
2018年 | 1138篇 |
2017年 | 885篇 |
2016年 | 877篇 |
2015年 | 990篇 |
2014年 | 1428篇 |
2013年 | 2106篇 |
2012年 | 3010篇 |
2011年 | 3115篇 |
2010年 | 1749篇 |
2009年 | 1459篇 |
2008年 | 2502篇 |
2007年 | 2731篇 |
2006年 | 2607篇 |
2005年 | 2327篇 |
2004年 | 2153篇 |
2003年 | 2068篇 |
2002年 | 1977篇 |
2001年 | 1480篇 |
2000年 | 1474篇 |
1999年 | 1237篇 |
1998年 | 451篇 |
1997年 | 420篇 |
1996年 | 421篇 |
1995年 | 374篇 |
1994年 | 375篇 |
1993年 | 335篇 |
1992年 | 1066篇 |
1991年 | 1048篇 |
1990年 | 979篇 |
1989年 | 933篇 |
1988年 | 814篇 |
1987年 | 831篇 |
1986年 | 804篇 |
1985年 | 774篇 |
1984年 | 620篇 |
1983年 | 484篇 |
1982年 | 353篇 |
1981年 | 311篇 |
1979年 | 575篇 |
1978年 | 340篇 |
1976年 | 294篇 |
1975年 | 344篇 |
1974年 | 374篇 |
1973年 | 316篇 |
1972年 | 294篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
A survey was performed on the radiotherapy practice of malignant pleural mesothelioma in The Netherlands and Belgium in 2002. Thirty-eight out of 47 centres (81%) responded. Prophylactic radiotherapy to intervention sites is given by 32/38 (84%) centres, with all centres offering palliative radiation. For both prophylactic and palliative indications, all centres use hypo-fractionated schedules. The present study shows that in the radiotherapy community in The Netherlands and in Belgium, a de facto consensus exists that both prophylactic and symptomatic radiotherapy to intervention sites of malignant pleural mesothelioma are effective and that hypo-fractionated schedules should be used. 相似文献
42.
43.
Maninder S Kalkat Ishtiaq Rahman Kostas Kotidis Ben Davies Robert S Bonser 《European journal of cardio-thoracic surgery》2007,32(2):250-254
BACKGROUND: In Marfan's syndrome, there is a paucity of data regarding intervention criteria for surgery of the dissected thoraco-abdominal aorta. METHODS: A retrospective analysis of 22 Marfan's patients with distal aortic dissection managed between September 1999 and April 2006 was performed. Serial diameters and linear expansion rates were calculated from imaging studies and the outcome of intervention was analysed. RESULTS: There were 14/22 male patients (median age 38 years), and 18 had prior aortic surgery. Surgery was recommended in 20 patients and undertaken in 19 (1 died prior to operation). Of the operated patients, 2 presented with rupture, 2 with airway obstruction, 1 with intermittent paraplegia and 14 underwent planned surgery for increased expansion rate or pain. All patients had residual type A or chronic type B dissection. The median aortic dimension at surgery was 6.7 cm (interquartile range (IQR) 5.5-8.2). The preoperative mean expansion rate increased from 0.5 cm/year to 1.7 cm/year (p<0.001), prior to operation. Fifteen patients underwent Crawford Extent II, two underwent Extent I and two underwent Extent III repair. Profound hypothermia and CSF drainage was used in 16 and 18 patients, respectively. There was no early mortality, paraplegia or renal failure. At a median postoperative follow-up of 56 months (range 6-86), the survival of the operated cohort was 90%. CONCLUSIONS: Thoraco-abdominal aortic aneurysm repair in Marfan's syndrome can be performed with good outcomes. Intervention should be based on size or accelerated expansion. Any role of endovascular management needs careful consideration. 相似文献
44.
45.
J P Michalski S Zanki J L Anderson H Walter 《Journal of clinical & laboratory immunology》1986,21(1):43-48
Mixtures of aqueous solutions of dextran and poly(ethylene glycol) form immiscible 2-phase systems that are suitable for the separation of viable, functionally-competent cells on the basis of their surface properties. With the appropriate choice of ionic composition, these systems will separate cells on the basis of charge-related surface characteristics. We have previously shown that in charge-sensitive phase systems, human B lymphocytes have a low partition coefficient (K) and T cells have an intermediate K. The cell subpopulation with the highest K values contains large null lymphocytes that have most of the antibody-dependent and natural killer activities. The present study further characterizes this latter cell subpopulation. 8-33% of peripheral blood lymphocytes in normal persons had high K values. About 50% of these cells had typical Giemsa-staining granules characteristic of killer cells and one third had Fc receptors, but lacked complement receptors. Although 15-30% of the cells with high K values formed rosettes with sheep erythrocytes, there was virtually no response to T-cell mitogens such as PHA and Con A. Mixing cells having high K values with mitogen-responsive T cells from intermediate cell fractions revealed no evidence of suppressor-cell activity to explain the poor mitogen response. The studies indicate that a heterogeneous population of cells share charge-related surface properties resulting in a high partition coefficient. These cells comprise a significant proportion of human peripheral blood lymphocytes and include virtually all of the large granular lymphocytes as well as a large population without this morphology that shares the feature of unresponsiveness to T-cell mitogens. 相似文献
46.
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
47.
Lucy Wong-Hernandez Daniel W. Wong G. Ben Selby 《中国康复理论与实践》2006,12(9):758-761
1Introduction Substanceabusecontinuestobeamongthemostsevereso cialandcostlyhealthproblemsdevastatingindividualsandtheir familiesintheUnitedStates.Initssimplestdefinition,sub stanceabuseisthecontinueduseofalcoholorotherdrugsde spiteknowledgeofhavingapersistentsocial,vocational,psy chologicalorphysicalproblemthatiscausedorexacerbatedby theuseofalcoholorotherdrugs(DSMIV TR,1994).All drugsofabuse,includingalcohol,aretoxicandcannegatively impacteverysysteminthehumanorganism.Protractedsub stance… 相似文献
48.
L L Polla S L Jacques R J Margolis M R Prince R R Anderson J A Parrish O T Tan 《Annales de dermatologie et de vénéréologie》1987,114(4):497-505
Since 1962, lasers have been used in dermatology and have become the first choice in the treatment of superficial, vascular ectasia. Lasers are unique sources of light; they are coherent, monochromatic, collimated and intense. By careful selection of wavelength, pulse duration, and intensity, it is often possible to selectively confine a laser effect to a specific histologic structure in tissue, depending upon the tissue properties. The ideal treatment of Port Wine Stains (PWS) should irreversibly damage the ectatic vessels but minimize heating of the epidermis and superficial dermis. A theory, called selective photothermolysis, predicts the optimal combination of laser parameters of achieving this ideal treatment of PWS to be a wavelength of 577 nm, a pulse duration of 0.35-10 msec, and an energy per surface area of about 7-8 J/cm2. Laser wavelength: The wavelength of 577 nm is preferred because it: maximizes the selective absorption by hemoglobin, minimizes absorption by epidermal melanin, provides sufficient depth of penetration in the blood to coagulate 0.1 mm vessels allows penetration of light into dermis up to 1 mm. Laser pulse duration: A pulse-width in the range of 0.35-10 msec allows the temperature elevation to be uniform inside the vessel and to be confined to the vessel area. Shorter pulses superheat the red blood cells causing explosive boiling and hemorrhage. Longer pulses allow heat to diffuse away from vessels, requiring greater energies per pulse to achieve vessel damage. An increased energy per pulse increases the risk of excessive damage to surrounding tissue.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
49.
Breast cancer is the most common cancer diagnosis for North American and Western European women. Increased knowledge in availability of genetic testing has helped to identify those women at high risk of eventually developing breast cancer. This has resulted in more women considering bilateral prophylactic mastectomy as a viable preventative option. Although the efficacy of the procedure has been established, much less is known about the psychological impact of undergoing this procedure. In order to assess these factors, we reviewed what is currently known about the psychological impact of undergoing bilateral prophylactic mastectomy. Searches were conducted and inclusion criteria revealed articles that focused on the psychological components involved with undergoing a bilateral prophylactic mastectomy. The findings are summarized and fell broadly into one or more of the following three areas: (1) satisfaction or regret following the surgery, (2) psychosocial functioning after the surgery, and (3) predictors of quality of life. Plastic surgery nurses have a unique opportunity to impact important psychological considerations, such as expectations of the early postoperative period, body image concerns, and psychological distress. 相似文献
50.
Philip S Wells Josdalyne L Anderson Marc A Rodger Nancy Carson Rebecca L Grimwood Steve P Doucette 《Blood coagulation & fibrinolysis》2006,17(7):533-538
The substitution of leucine for valine at amino acid position 34 of the factor XIII gene is commonly referred to as FXIII Val34Leu polymorphism. The homozygous leucine/leucine genotype has been reported to confer protection against venous thromboembolism, but previous studies have not evaluated a population limited to those with idiopathic venous thromboembolism. The primary objective of the study was to determine whether the FXIII Val34Leu polymorphism is independently associated with the occurrence of idiopathic venous thromboembolism. We prospectively enrolled consecutive patients with at least one objectively confirmed idiopathic venous thromboembolism. Friends of cases were recruited as controls and matched to cases by sex, ethnicity, and age. All participants were tested for the FXIII Val34Leu polymorphism in addition to several well-known thrombophilias. Data from 309 cases and 306 controls were analyzed. The FXIII leucine/leucine genotype was present in 4.9% of cases and 6.5% of controls. An adjusted odds ratio of 0.59 (95% confidence interval, 0.25-1.38) was found for the recessive model and 0.69 (95% confidence interval, 0.46-1.02) for the dominant model. Our results do not support an independent association of the FXIII Val34Leu polymorphism with idiopathic venous thromboembolism in our Caucasian Canadian study population. 相似文献