首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   11542篇
  免费   1027篇
  国内免费   15篇
耳鼻咽喉   91篇
儿科学   223篇
妇产科学   237篇
基础医学   1489篇
口腔科学   169篇
临床医学   1594篇
内科学   2152篇
皮肤病学   148篇
神经病学   973篇
特种医学   492篇
外科学   1789篇
综合类   279篇
一般理论   19篇
预防医学   1359篇
眼科学   169篇
药学   887篇
  1篇
中国医学   13篇
肿瘤学   500篇
  2023年   66篇
  2022年   93篇
  2021年   184篇
  2020年   118篇
  2019年   178篇
  2018年   205篇
  2017年   157篇
  2016年   186篇
  2015年   189篇
  2014年   258篇
  2013年   367篇
  2012年   552篇
  2011年   609篇
  2010年   350篇
  2009年   332篇
  2008年   525篇
  2007年   536篇
  2006年   496篇
  2005年   549篇
  2004年   543篇
  2003年   441篇
  2002年   405篇
  2001年   404篇
  2000年   395篇
  1999年   409篇
  1998年   163篇
  1997年   109篇
  1996年   122篇
  1995年   110篇
  1994年   101篇
  1993年   82篇
  1992年   297篇
  1991年   267篇
  1990年   227篇
  1989年   243篇
  1988年   224篇
  1987年   200篇
  1986年   186篇
  1985年   178篇
  1984年   124篇
  1983年   142篇
  1982年   77篇
  1981年   72篇
  1979年   122篇
  1977年   83篇
  1975年   62篇
  1974年   91篇
  1973年   83篇
  1972年   78篇
  1971年   83篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
PURPOSE: Elective cosmetic surgery is expanding in the UK in both the public and private sectors. Because resources are constrained, many cosmetic procedures are being excluded within the National Health Service. If guidelines on who can receive such surgery are to be evidence-based, information is needed about the level of dysfunction in patients referred for elective surgery and whether this is related to their degree of physical abnormality. METHOD: Consecutive patients referred to a regional plastic surgery and burns unit for assessment for elective cosmetic surgery completed standardised measures of physical and psychosocial dysfunction, and indicated their perception of the degree of their abnormality and their preoccupation with it. We distinguished between patients referred for physical reasons or appearance reasons only, and compared levels of physical and psychosocial dysfunction in each with published values for community and clinical samples. Surgeons indicated patients' degree of objective abnormality, and we identified the relationship of dysfunction with perceived and objective abnormality and preoccupation. RESULTS: Whether patients sought surgery for physical or appearance reasons, physical function was normal. Those seeking surgery for appearance reasons only had moderate psychosocial dysfunction, but were not as impaired as clinical groups with psychological problems. Patients seeking the correction of minor skin lesions for purely appearance reasons reported excellent physical and psychosocial function. Level of function was related (negatively) to patients' preoccupation with abnormality rather than to their perceived or objective abnormality. CONCLUSIONS: In general, patients referred for elective cosmetic surgery did not present with significant levels of dysfunction. Moreover, levels of functioning were related to preoccupation rather than to objective abnormality. Therefore, for most patients, whether surgical treatment is generally appropriate is questionable. Future guidelines must seek to identify the small minority who do have a clinical need for surgery.  相似文献   
62.
Braun Jr  Martin  MD  Cook Joel  MD 《Dermatologic surgery》2005,31(S2):995-1005
Background. Surgical defects following the extirpation of cutaneous neoplasia may present challenges to the dermatologic surgeon. There are many repair options for an individual defect, including second-intention healing, primary closure, skin graft, and skin flap closure. The island pedicle flap is a random pattern advancement flap well suited to reconstruct a variety of small- to intermediate-sized soft tissue wounds.
Objective. To review the utility of the island pedicle flap in reconstructive dermatologic surgery and to detail the operative technique to achieve reproducible functional and esthetic results.
Methods. The method of flap reconstruction is presented. A variety of defects repaired with this technique are reviewed.
Results. The subcutaneous island pedicle flap yielded excellent functional and cosmetic repair of the presented defects with minimal operative morbidity. Secondary to a well-preserved central vascular pedicle, complications are infrequent.
Conclusions. The random pattern island pedicle flap is a versatile and robust flap used to repair a variety of soft tissue wounds in a single-stage procedure with reproducible operative outcomes.  相似文献   
63.
BACKGROUND: Hypertension is a potential risk factor for allograft coronary vasculopathy. We evaluated the efficacy of angiotensin-converting enzyme (ACE) inhibitors and calcium antagonists, and their combined use, on the development of coronary vasculopathy in hypertensive heart transplant recipients. METHODS: Eighty-two heart transplant recipients underwent serial intravascular ultrasound (IVUS) analysis at baseline (within 1 month) and at 1 year after transplantation and were evaluated for the development of coronary vasculopathy. Patients were divided into 4 groups. Nineteen normotensive recipients received no treatment, control (Group A). Hypertensive patients were treated with either ACE inhibitors (Group B, n = 37), calcium antagonists (Group C, n = 16), or both (Group D, n = 10). RESULTS: We found a significant reduction in IVUS indices of coronary vasculopathy in heart transplant recipients who used a combination of an ACE inhibitor and a calcium antagonist compared with recipients who used either drug alone (p < 0.05). This synergistic efficacy was independent of the baseline indices evaluated in a multivariate regression analysis model and was noted despite comparable mean arterial pressure among the 3 hypertensive groups at 1 year, thus suggesting the presence of a synergistic anti-proliferative effect beyond the anti-hypertensive efficacy. CONCLUSIONS: The combined use of an ACE inhibitor and a calcium antagonist is more effective than the individual use of either drug alone on the development of coronary vasculopathy in cardiac transplant recipients. Large randomized clinical trials are warranted to evaluate such a synergistic efficacy.  相似文献   
64.
Melanocytic lesions of uncertain malignant potential (MUMP) is a term which is useful in identifying melanocytic tumours where the distinction between benign and malignant is a histological problem. Sentinel node biopsy is recognised to provide unmatched prognostic information in melanoma patients, but has recently been advocated for diagnostic purposes in MUMP. We present the case of a seven-year-old girl who presented with a six-month history of a changing pigmented lesion on her left upper arm. Excision biopsy not only showed a melanocytic lesion with some spitzoid features but also marked atypia making it appropriate to use the term MUMP. Sentinel node biopsy was undertaken. This case demonstrates that sentinel node biopsy can be performed safely in children. Given the low morbidity of the procedure we advocate that this technique should be considered in this difficult diagnostic situation to further the management of these patients.  相似文献   
65.
66.
This work describes the design and construction of a device that facilitates the loading of DNA samples onto polyacrylamide gels for detection in the Perkin Elmer/Applied Biosystems (PE/ABI) 373 and 377 DNA sequencing instruments. The device is mounted onto the existing gel cassettes and makes the process of loading high-density gels less cumbersome while the associated time and errors are reduced. The principle of operation includes the simultaneous transfer of the entire batch of samples, in which a spring-loaded air cylinder generates positive pressure and flexible silica capillaries transfer the samples. A retractable capillary array carrier allows the delivery ends of the capillaries to be held up clear of the gel during loader attachment on the gel plates, while enabling their insertion in the gel wells once the device is securely mounted. Gel-loading devices capable of simultaneously transferring 72 samples onto the PE/ABI 373 and 377 are currently being used in our production sequencing groups while a 96-sample transfer prototype undergoes testing.  相似文献   
67.
Multiple sclerosis is a demyelinating disease of the central nervous system with genetic, viral and autoimmune characteristics. Myelin basic protein (MBP) is a suspected target autoantigen since it induces experimental autoimmune encephalomyelitis, an animal model closely resembling multiple sclerosis. The disease is mediated by Class II restricted, MBP-reactive T cells possessing the T helper/inducer phenotype. In the present study, we have isolated MBP-reactive T cell clones from the peripheral blood of a chronic progressive multiple sclerosis patient. The clones displayed blastogenic memory responses when rechallenged with the autoantigen and irradiated autologous lymphocytes. MBP recognition by the autoantigen-reactive T lymphocytes was restricted by major histocompatibility complex Class II antigens. Both CD4+8- and CD4-8+ MBP-reactive T cell clones were obtained.  相似文献   
68.
Summary Type 2 (non-insulin-dependent) diabetes is associated with the deposition of islet amyloid. The major formative peptide, islet amyloid polypeptide, has recently been characterised and an abnormality of the structure or expression of this gene is a possible candidate for the inherited component of Type 2 diabetes. A restriction fragment length polymorphism of the gene has been identified with Pvu II. To study the relationship between the islet amyloid polypeptide gene and Type 2 diabetes, two distinct genetic approaches have been undertaken. Firstly, non-linkage has been demonstrated in four pedigrees, with four normoglycaemic first degree relatives having an allele associated with diabetes in other family members, and one affected relative not having the putatively associated allele. The LOD score taking age-related penetrance into account was –1.68, making linkage unlikely (p=0.02). Secondly, in a population-based restriction fragment length polymorphism survey, no linkage disequilibrium of the alleles was found between a population of unrelated Caucasian subjects with Type 2 diabetes and a normal population. A mutation in or near the islet amyloid polypeptide gene is thus unlikely to be a common cause of Type 2 diabetes.  相似文献   
69.
Computed radiography in musculoskeletal imaging: state of the art.   总被引:1,自引:0,他引:1  
Computed radiography is a 2K x 2K x 10 bit digital radiographic system that replaces the film-screen combination with a photo-stimulable phosphor plate. The advantages of this relatively new technology include linear detector response, improved detector efficiency, and digital processing capabilities. Musculoskeletal applications benefit significantly from these attributes, which result clinically in the ability to reduce both radiation dose and number of exposures. Studies of observers' performance have shown no statistically significant difference in diagnostic accuracy between film-screen and computed radiographic musculoskeletal images. Computed radiography is particularly useful in the evaluation of the musculoskeletal system in traumatized patients with portable radiographs, spine radiographs, scoliosis studies, and depiction of soft-tissue abnormalities. Limitations include change in image format and size, high cost, decreased spatial resolution, restricted throughput, increased perception of noise, and new artifacts that must be recognized. Spatial resolution limitations of computed radiography in identification of fine detail information can be improved by using magnification techniques. Radiation dose reduction with an exposure decrease of 25-50% can be achieved without loss of diagnostic accuracy, although this depends on the examination and the abnormality. An interactive workstation is important in the use of a computed radiographic system with capabilities to adjust display parameters to best depict images and disease. We conclude that computed radiography is an alternative to film-screen radiography without significant differences in diagnostic quality in the evaluation of musculoskeletal images.  相似文献   
70.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号