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   8617篇
  免费   544篇
  国内免费   47篇
耳鼻咽喉   97篇
儿科学   264篇
妇产科学   245篇
基础医学   1399篇
口腔科学   460篇
临床医学   648篇
内科学   1815篇
皮肤病学   219篇
神经病学   736篇
特种医学   100篇
外科学   1062篇
综合类   52篇
一般理论   4篇
预防医学   786篇
眼科学   156篇
药学   593篇
中国医学   52篇
肿瘤学   520篇
  2024年   6篇
  2023年   66篇
  2022年   192篇
  2021年   323篇
  2020年   213篇
  2019年   258篇
  2018年   323篇
  2017年   203篇
  2016年   244篇
  2015年   254篇
  2014年   398篇
  2013年   511篇
  2012年   737篇
  2011年   773篇
  2010年   417篇
  2009年   330篇
  2008年   625篇
  2007年   570篇
  2006年   521篇
  2005年   437篇
  2004年   422篇
  2003年   403篇
  2002年   350篇
  2001年   49篇
  2000年   45篇
  1999年   56篇
  1998年   59篇
  1997年   36篇
  1996年   34篇
  1995年   28篇
  1994年   28篇
  1993年   23篇
  1992年   30篇
  1991年   28篇
  1990年   23篇
  1989年   22篇
  1988年   17篇
  1987年   9篇
  1986年   16篇
  1985年   8篇
  1984年   15篇
  1983年   7篇
  1982年   11篇
  1981年   8篇
  1980年   10篇
  1979年   10篇
  1978年   7篇
  1973年   5篇
  1972年   5篇
  1970年   7篇
排序方式: 共有9208条查询结果,搜索用时 109 毫秒
1.
Radiodermatitis is one of the commonest side effects of radiotherapy. They are usually assessed by semi‐quantitative clinical scores, which are not validated and may be subject to inter‐observer variability. A few previous studies suggested that high‐frequency ultrasonography (HF‐USG) is useful in the assessment of the acute phase of radiation dermatitis in breast cancer patients. (a) To monitor skin changes by HF‐USG during the course of radiotherapy due to head and neck cancers, and (b) to determine whether there is any connection between skin sonograms and the skin scoring criteria. This prospective, observational study includes patients diagnosed with head and neck cancers, treated with radiotherapy or concomitant chemoradiation. The final analysis includes six patients. In every patient, the HF‐USG as well as dermatological assessment (target lesion score—TLS and CACE v. 4.0) were performed 4×: before, in the middle, day after, and 3 months after radiotherapy. There were significant differences between non‐irradiated skin thickness and thickness of skin with clinically obvious radiodermatitis (TLS grade 1‐4; P < .0001), as well as between irradiated, unchanged skin thickness (TLS grade 0) and thickness of skin with clinically obvious radiodermatitis (TLS grade 1‐4; P = .0002). There was no significant difference between non‐irradiated and irradiated, unchanged skin thickness (TLS grade 0; P = .9318). In four patients, we demonstrated subepidermal low echogenic band (SLEB). HF‐USG can be useful tool to noninvasive and objective assessment of skin changes during radiotherapy.  相似文献   
2.
Objective: Polyunsaturated fatty acids n-3 (PUFA n-3) have shown effects in reducing tumor growth, in particular eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) abundantly present in fish oil (FO). When these fatty acids are provided in the diet, they alter the functions of the cells, particularly in tumor and immune cells. However, the effects of α-linolenic fatty acid (ALA), which is the precursor of EPA and DHA, are controversial. Thus, our objective was to test the effect of this parental fatty acid. Methods: Non-tumor-bearing and tumor-bearing Wistar rats (70 days) were supplemented with 1 g/kg body weight of FO or Oro Inca® (OI) oil (rich in ALA). Immune cells function, proliferation, cytokine production, and subpopulation profile were evaluated. Results: We have shown that innate immune cells enhanced phagocytosis capacity, and increased processing and elimination of antigens. Moreover, there was a decrease in production of pro-inflammatory cytokines (tumor necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6)) by macrophages. Lymphocytes showed decreased proliferation capacity, increased cluster of differentiation 8 (CD8+) subpopulation, and increased TNF-α production. Conclusions: Oil rich in ALA caused similar immune modulation in cancer when compared with FO.  相似文献   
3.
4.
Classical Kaposi sarcoma (KS) usually appears on lower extremities accompanied or preceded by local lymphedema. However, the development in areas of chronic lymphedema of the arms following mastectomy, mimicking a Stewart–Treves syndrome, has rarely been described. We report an 81‐year‐old woman who developed multiple, erythematous to purple tumors, located on areas of post mastectomy lymphedema. Histopathological examination evidenced several dermal nodules formed by spindle‐shaped cells that delimitated slit‐like vascular spaces with some red cell extravasation. Immunohistochemically, the human herpesvirus type 8 (HHV‐8) latent nuclear antigen‐1 was detected in the nuclei of most tumoral cells confirming the diagnosis of KS. Lymphedema could promote the development of certain tumors by altering immunocompetence. Although angiosarcoma (AS) is the most frequent neoplasia arising in the setting of chronic lymphedema, other tumors such as benign lymphangiomatous papules (BLAP) or KS can also develop in lymphedematous limbs. It is important to establish the difference between AS and KS because their prognosis and treatment are very different. Identification by immunohistochemistry of HHV‐8 is useful for the distinction between KS and AS or BLAP.  相似文献   
5.
6.
The use of endogenous Protoporphyrin IX generated through the heme biosynthetic pathway after administration of 5-aminolevulinic acid (ALA) has led to many applications in photodynamic therapy (PDT). In Buenos Aires, Argentina, the Centro de Investigaciones sobre Porfirinas y Porfirias (CIPYP), reported for the first time, in 1975, porphyrin synthesis from ALA in highly dividing plant tissues. Increased porphyrin synthesis in tumours as well as cell photosensitisation was reported soon after. Our group is also interested in studying the use of new synthetic lipophilic derivatives of ALA as well as ALA delivery in liposomes. We have elucidated the mechanism of ALA transport in mammalian and yeast cells. The interactions between ALA-PDT and nitric oxide were investigated in three murine adenocarcinoma cell lines. In the National University of Río Cuarto, Córdoba, a group is devoted to the synthesis of new porphyrin-derived photosensitisers to study their effects on photoinactivation of bacterial and mammalian cells death by PDT. At the Centre of Electron Microscopy of the Cordoba National University, a prototype of a 630 nm noncoherent light source was designed and constructed. Cost of the light source and scarce knowledge of the benefits of PDT by physicians limit the spread of the treatment throughout the country.  相似文献   
7.
Abstract: The current study examined the extent to which mothers, fathers, teachers, and teenage friends influenced Latino adolescents’ academic motivation. Using path analysis, separate models were tested for 154 Latino boys and 156 Latina girls. Findings indicated that mothers’ and teachers’ academic support were positively related to adolescent girls’ academic motivation, and fathers’ and teachers’ academic support were positively related to adolescent boys’ academic motivation. The salience of teachers’ support, possible reasons for gender differences, and implications for future research are discussed.  相似文献   
8.
We report a case of a prepubertal girl with juvenile primary hypothyroidism presenting as ovarian cysts and precocious puberty. The 7-year-old female was referred to our clinic because of a pelvic/abdominal mass and vaginal bleeding. Besides these findings, on physical examination we noticed the thyroid gland globally increased and the presence of secondary sexual characteristics. Based upon the clinical profile and investigations, the patient was diagnosed with juvenile primary hypothyroidism due to autoimmune thyroiditis. The cysts and precocious puberty resolved spontaneously after the simple replacement of thyroid hormone. It is important to bear in mind hypothyroidism in cases of girls presenting ovarian cysts and precocious puberty in order to avoid unnecessary surgery on the ovaries.  相似文献   
9.
The incidence of lower urinary tract dysfunction increases during the climacteric, and there is embryological, biochemical and epidemiologic evidence to suggest that depleted estrogen status is at least partially responsible. Twelve climacteric women underwent full assessment before and 1 year after treatment with a 50 mg subcutaneous estradiol implant +5 mg norethisterone for 7 days per month. Assessment consisted of a symptoms questionnaire, midstream urine sample, uroflowmetry, videocystourethrography with pressure flow studies, and urethral pressure profilometry. Subjectively, only the symptom of nocturia significantly improved. There was no change in flow variables but there was a significant decrease in residual urine and the degree of bladder base descent. Cystometric capacity was slightly but significantly decreased, and two patients developed genuine stress incontinence whilst on treatment. Nonetheless, there was a significant improvement in urethral pressures at rest but not under stress. This effect was predominantly in the proximal urethra. These data do not support the contention that estrogen replacement therapy is beneficial for lower urinary tract dysfunction during the climacteric.  相似文献   
10.
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