全文获取类型
收费全文 | 7509篇 |
免费 | 499篇 |
国内免费 | 89篇 |
专业分类
耳鼻咽喉 | 64篇 |
儿科学 | 171篇 |
妇产科学 | 347篇 |
基础医学 | 895篇 |
口腔科学 | 107篇 |
临床医学 | 855篇 |
内科学 | 1736篇 |
皮肤病学 | 78篇 |
神经病学 | 544篇 |
特种医学 | 412篇 |
外科学 | 969篇 |
综合类 | 132篇 |
一般理论 | 3篇 |
预防医学 | 377篇 |
眼科学 | 163篇 |
药学 | 569篇 |
中国医学 | 43篇 |
肿瘤学 | 632篇 |
出版年
2023年 | 46篇 |
2022年 | 82篇 |
2021年 | 193篇 |
2020年 | 93篇 |
2019年 | 159篇 |
2018年 | 213篇 |
2017年 | 151篇 |
2016年 | 123篇 |
2015年 | 234篇 |
2014年 | 294篇 |
2013年 | 381篇 |
2012年 | 573篇 |
2011年 | 525篇 |
2010年 | 313篇 |
2009年 | 333篇 |
2008年 | 457篇 |
2007年 | 392篇 |
2006年 | 385篇 |
2005年 | 395篇 |
2004年 | 359篇 |
2003年 | 290篇 |
2002年 | 236篇 |
2001年 | 218篇 |
2000年 | 183篇 |
1999年 | 191篇 |
1998年 | 71篇 |
1997年 | 44篇 |
1996年 | 43篇 |
1995年 | 48篇 |
1994年 | 34篇 |
1993年 | 24篇 |
1992年 | 106篇 |
1991年 | 80篇 |
1990年 | 82篇 |
1989年 | 59篇 |
1988年 | 72篇 |
1987年 | 72篇 |
1986年 | 62篇 |
1985年 | 64篇 |
1984年 | 66篇 |
1983年 | 31篇 |
1982年 | 24篇 |
1979年 | 37篇 |
1978年 | 26篇 |
1977年 | 23篇 |
1976年 | 19篇 |
1975年 | 33篇 |
1974年 | 23篇 |
1973年 | 19篇 |
1971年 | 17篇 |
排序方式: 共有8097条查询结果,搜索用时 0 毫秒
991.
Wang KY; Kimmey MB; Nyberg DA; Mack LA; Haggitt RC; Shuman WP; Franklin DW; Silverstein FE 《Radiology》1987,165(3):827-829
Six normal and 16 neoplastic colorectal specimens were examined with 8.5-MHz ultrasound (US). An articulated system facilitated precise spatial correlation between US and histologic sections. Images were blindly interpreted and then compared with histologic results. All six normal specimen showed five distinct echo layers and were distinguished from neoplastic specimens by all the observers. The central echogenic layer, corresponding to the submucosa, is useful in determining the depth of origin of a neoplasm and the presence of submucosal invasion. US had an accuracy of 92.5% in demonstrating invasion of the submucosa and 77% for invasion of the muscularis externa. For mucosal neoplasms with invasion through the muscularis externa and extension into the subserosal tissues, nearly 90% of US interpretations were correct. High-frequency US may be useful in determining the depth of invasion of mucosal tumors with respect to the submucosa and in differentiating mucosal from extramural masses. 相似文献
992.
Two colloidal radiopharmaceuticals, Au-198 and Tc-99m antimony, were used to evaluate the lymphatic drainage of the testis in experimental animals and humans. One to 24 hours after direct intratesticular injection of Au-198 colloid in dogs and 4-6 hours after injection of Tc-99m antimony colloid in men, distribution within retroperitoneal lymph nodes was demonstrated. Uptake within the para-aortic lymph nodes primarily draining the testis was decreased following proximal ligation of the spermatic vessels in dogs. Testicular lymphoscintigraphy successfully demonstrated an intact spermatic cord lymphatic communication to the para-aortic nodes in five of six patients with chronic lower-extremity lymphedema. When the intact testicle and spermatic cord were transposed to the thigh in a patient with chronic lymphedema of the lower extremity, percutaneous pedal lymphoscintigraphy successfully demonstrated uptake within the para-aortic lymph nodes draining the ipsilateral testis. 相似文献
993.
Ren-Shyan Liu Lee-Shing Chu San-Hui Yen Chen-Pei Chang Kuo-Liang Chou Liang-Chi Wu Chi-Wei Chang Mun-Tain Lui Kuang Y Chen Shin-Hwa Yeh 《European journal of nuclear medicine and molecular imaging》1996,23(10):1384-1387
Odontogenic infections are a potential risk for patients who receive cervicofacial radiotherapy and should be treated before irradiation. Anaerobic microbial infections are the most common causes. This study assessed the value of the hypoxic imaging agent fluorine-18 fluoromisonidazole (FMISO) in detecting anaerobic odontogenic infections. Positron emission tomography (PET) imaging was performed at 2 h after injection of 370 MBq (10 mCi) of FMISO in 26 nasopharyngeal carcinoma patients and six controls with healthy teeth. Tomograms were interpreted visually to identify hypoxic foci in the jaw. All patients received thorough dental examinations as a pre-radiotherapy work-up. Fifty-one sites of periodontitis, 15 periodontal abscesses, 14 sites of dental caries with root canal infection, 23 sites of dental caries without root canal infection, and seven necrotic pulps were found by dental examination. Anaerobic pathogens were isolated from 12 patients. Increased uptake of FMISO was found at 45 out of 51 sites of periodontitis, all 15 sites of periodontal abscess, all 14 sites of dental caries with root canal infection, all seven sites of necrotic pulp and 15 sites of dental caries without obvious evidence of active root canal infection. No abnormal uptake was seen in the healthy teeth of patients or in the six controls. The diagnostic sensitivity, specificity, positive and negative predictive values, and accuracy of FMISO PET scan in detecting odontogenic infections were 93%, 97%, 84%, 99% and 96%, respectively.18F-fluoride ion bone scan done in three patients showed that18F-fluoride ion plays no role in the demonstration of anaerobic odontogenic infection. FMISO PET scan is a sensitive method for the detection of anaerobic odontogenic infections, and may play a complementary role in the evaluation of the dental condition of patients with head and neck tumours prior to radiation therapy. 相似文献
994.
An autopilot for a transport aircraft is designed using mixed H2 and H∞ optimal control. The control law design technique allows real parameter uncertainty to be accounted for in the design process. The autopilot consists of an inner loop that controls aircraft heading in response to external commands and an outer loop that tracks a localizer beam so that the aircraft is properly aligned with the runway for landing. The problem formulation and the robust control law design technique allow a wide range of performance and robustness requirements to be met. Analysis of the closed-loop system shows the controller performance and robustness for a number of flight conditions through two separate approach profiles. 相似文献
995.
High-signal-intensity rim surrounding uterine leiomyomas on MR images: pathologic correlation 总被引:7,自引:0,他引:7
A high-intensity rim surrounding uterine leiomyomas was identified on T2-weighted magnetic resonance (MR) images in five of 13 patients with histopathologically confirmed leiomyomas. These peripheral high-intensity rims were not associated with subject age or with size, location, or degeneration of the leiomyomas. Histologic examination revealed markedly dilated lymphatic vessels, dilated veins, edema, or a combination of these features to correspond to the location of the high-intensity rims. These benign causes of high intensity in the myometrium should not be confused with clinically important processes such as adenomyosis or invasion by endometrial carcinoma. 相似文献
996.
Protein kinase C-like immunoreactivity in rod bipolar cells of the rat retina: a developmental study 总被引:2,自引:0,他引:2
In the retina of a variety of vertebrate species, a monoclonal antibody against protein kinase C (PKC) has been shown to label preferentially bipolar cells. Although the functional consequences of PKC activation in these cells is yet to be revealed, the present study was motivated in part by the possibility that the antibody might be used as a selective marker for examining the development of bipolar cells in the rat retina. Here, the developmental pattern and the dynamic changes of retinal cells expressing PKC-like immunoreactivity (PKC-LI) were studied and analyzed throughout postnatal life until adulthood. Upon its initial detection by immunohistochemistry on postnatal day (PD)-10, faint PKC-LI was limited to the central region of the retina, labeling cell bodies located at the scleral margin of the inner nuclear layer (INL) adjacent to the outer plexiform layer (OPL). On subsequent days, PKC-LI spread progressively to the peripheral retina and axon terminal bulbs at the vitreal margin of the inner plexiform layer (IPL) began showing the first signs of immunoreactive labeling. Not until PD-15, the time of eye opening, did PKC-LI in these cells increase to the extent such that their thin axons were immunoreactive. Each of these axons traversed the entire thickness of the IPL and divided into two or three short branches before ending as enlarged terminal bulbs. The morphology and the location of PKC-LI cells in both the developing and adult retina observed in our study are consistent with them being rod bipolar cells. By the end of the fourth postnatal week, the rod bipolar cells appeared mature, resembling those found in the adult.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
997.
Gold K.F. Pastores G.M. Botteman M.F. Yeh J.M. Sweeney S. Aliski W. Pashos C.L. 《Quality of life research》2002,11(4):317-327
This paper is the first of its kind to study the impact of Fabry disease (FD) in affected males, and shows that FD is associated with a significant decline in several domains. Using the medical outcomes study (MOS) SF-36 and a FD-specific questionnaire, we compared the observations found among these patients with that obtained for the general US population and other chronic disease states, including Gaucher disease (GD) (another lysosomal storage disorder), end-stage renal disease, stoke and AIDS. Patients with FD have a score profile most similar to patients with AIDS. In comparison with patients with GD, Fabry patients score substantially lower across all domains. Using simple linear regression, potential predictors of health-related quality of life (HRQOL) for Fabry patients were also determined. As in the general population, stroke, cardiac problems and renal disease lead to substantial decrement in HRQOL. In addition, two disease specific symptoms (acroparesthesia and anhidrosis) and pain are also predictors of decreased quality of life. Currently, no specific therapy for FD exists. As enzyme therapy for FD becomes increasingly available, it will be interesting to evaluate the therapy's impact on the quality of life of patients. 相似文献
998.
999.
1000.
The effects of sucrose and corticosterone on the expression of intestinal sucrase activity in preweanling rat pups were studied using an artificial rearing (AR) technique. When AR rat pups were isocalorically fed diets containing lactose or sucrose, or a carbohydrate-free diet from d 12-16, jejunal and ileal sucrase and maltase activities were induced to similar levels in all AR rats, whereas ileal lactase activity was precociously decreased. In separate experiments, enzyme activities were measured in ileal isografts subcutaneously implanted in littermates at birth. In AR rats fed the lactose diet, these isografts showed sucrase and maltase activities comparable with those of host ileum and also to isografts from AR rats fed the sucrose diet. In contrast, lactase activity was significantly higher in isografts than host ileum in all AR rats. Serum corticosterone levels were significantly elevated in AR rats for 24 h after intragastric cannular implantation. Precocious expression of ileal sucrase activity occurred in corticosterone treated, but not in untreated, adrenalectomized AR rats. In conclusion, dietary sucrose has no specific role in enhancing intestinal sucrase activity, and endogenous corticosterone is responsible for the induction of sucrase activity in AR rats. 相似文献