全文获取类型
收费全文 | 341884篇 |
免费 | 30631篇 |
国内免费 | 12116篇 |
专业分类
耳鼻咽喉 | 2646篇 |
儿科学 | 5160篇 |
妇产科学 | 4390篇 |
基础医学 | 57039篇 |
口腔科学 | 6742篇 |
临床医学 | 23854篇 |
内科学 | 55635篇 |
皮肤病学 | 5271篇 |
神经病学 | 31534篇 |
特种医学 | 8930篇 |
外国民族医学 | 93篇 |
外科学 | 24362篇 |
综合类 | 44062篇 |
现状与发展 | 40篇 |
一般理论 | 6篇 |
预防医学 | 14372篇 |
眼科学 | 3432篇 |
药学 | 53733篇 |
78篇 | |
中国医学 | 12780篇 |
肿瘤学 | 30472篇 |
出版年
2023年 | 5411篇 |
2022年 | 7204篇 |
2021年 | 13993篇 |
2020年 | 12328篇 |
2019年 | 11736篇 |
2018年 | 11348篇 |
2017年 | 11258篇 |
2016年 | 11234篇 |
2015年 | 13041篇 |
2014年 | 19948篇 |
2013年 | 22823篇 |
2012年 | 19418篇 |
2011年 | 22643篇 |
2010年 | 18746篇 |
2009年 | 19149篇 |
2008年 | 18995篇 |
2007年 | 17314篇 |
2006年 | 15319篇 |
2005年 | 13306篇 |
2004年 | 11578篇 |
2003年 | 10638篇 |
2002年 | 8542篇 |
2001年 | 7284篇 |
2000年 | 6074篇 |
1999年 | 5302篇 |
1998年 | 4459篇 |
1997年 | 4328篇 |
1996年 | 3736篇 |
1995年 | 3707篇 |
1994年 | 3421篇 |
1993年 | 2986篇 |
1992年 | 2443篇 |
1991年 | 2250篇 |
1990年 | 1852篇 |
1989年 | 1594篇 |
1988年 | 1449篇 |
1987年 | 1282篇 |
1986年 | 1312篇 |
1985年 | 2257篇 |
1984年 | 2318篇 |
1983年 | 1665篇 |
1982年 | 1753篇 |
1981年 | 1502篇 |
1980年 | 1239篇 |
1979年 | 1033篇 |
1978年 | 701篇 |
1977年 | 557篇 |
1976年 | 571篇 |
1975年 | 432篇 |
1974年 | 318篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
Lin Li Wei Wu Wanchao Zheng Qiao Hui Chunna Zhao 《APMIS : acta pathologica, microbiologica, et immunologica Scandinavica》2022,130(1):21-25
We aimed to explore the correlation between P27 expression and Helicobacter pylori (H. pylori) infection in gastric cancer, so as to provide evidence for understanding the pathogenesis of gastric cancer caused by H. pylori infection. A total of 82 samples of gastric cancer tissues and 56 samples of tumor-adjacent normal tissues collected from the gastrectomy were enrolled in this study. Then, 14C-urease breathing test was carried out to evaluate the infection of H. pylori in gastric cancer tissues, the expression of P27 in the tissue samples was detected by the immunohistochemistry staining, and the correlation between the H. pylori infection and P27 expression in gastric cancer was analyzed. Of 82 gastric cancer patients, there were 53 patients with H. pylori infection (64.63%). Among the patients with highly or moderately differentiated gastric cancer, the expression of P27 was much higher than that of patients with poorly differentiated gastric cancer (p < 0.01). Besides, comparison of the P27 expression between males and females, among different age groups, tumor sizes, TNM stages, tumor infiltration degrees, or lymph node metastasis, showed no significant differences (p > 0.05). Analysis of the correlation revealed that P27 expression was negatively correlated with the infection of H. pylori (p < 0.01). Multifactorial logistics regression analysis indicated that tumor differentiation was a risk factor of P27-positive expression in gastric cancer tissues (p < 0.01). In addition, P27 expression in the gastric cancer tissues was lower than that in the tumor-adjacent normal tissues (p < 0.01). In gastric cancer patients, expression of P27 is correlated with H. pylori infection which, via downregulating P27, can cause the cancerization of gastric mucosa, and P27, for its role in the development and progression of gastric cancer, is a potential auxiliary indicator for clinical diagnosis whether gastric cancer is complicated with H. pylori infection. So, P27 is a key indicator for diagnosis, treatment, and prognostic evaluation of disease in the advanced stage. 相似文献
42.
子宫浆液性癌(uterine serous carcinoma,USC)是一种特殊类型的子宫内膜癌。有别于常见的子宫内膜样腺癌,USC较为少见,且恶性程度高,侵袭转移风险高,临床上预后较差。随着子宫内膜癌分子学研究的不断深入,分子学特征被应用于子宫内膜癌的病理分型诊断、治疗和预后评价中。研究发现USC中存在多种基因的突变,这些相关基因的突变对该病的诊断和预后具有重要的指导意义。同时,特异性的分子学改变为USC的靶向治疗提供了潜在的治疗靶点。目前,多种靶向治疗手段包括人表皮生长因子受体2(human epidermal growth factor receptor 2,HER2)抑制剂、免疫检查点抑制剂、抗血管生成治疗、磷脂酰肌醇3激酶(phosphoinositide 3-kinases,PI3K)通路抑制剂和多腺苷二磷酸核糖聚合酶[poly(ADP-ribose) polymerase,PARP]抑制剂等被应用于USC的临床治疗研究中,针对性的靶向治疗有望成为USC治疗的新突破。 相似文献
43.
Cadmium is a toxic metal that can damage the brain and other organs. This study aimed to explore the protective effects of Potentilla anserine L. polysaccharide (PAP) against CdCl2-induced neurotoxicity in N2a and SH-SY5Y cells and in the cerebral cortex of BALB/c mice. In addition, we aimed to identify the potential mechanisms underlying these protective effects. Relative to CdCl2 treatment alone, pretreatment with PAP prevented the reduction in cell viability evoked by CdCl2, decreased rates of apoptosis, promoted calcium homeostasis, decreased ROS accumulation, increased mitochondrial membrane potential, inhibited cytochrome C and AIF release, and prevented the cleavage of caspase-3 and PARP. In addition, PAP significantly decreased the CdCl2-induced phosphorylation of CaMKII, Akt, and mTOR. In conclusion, PAP represents a potential therapeutic agent for the treatment of Cd-induced neurotoxicity, functioning in part via attenuating the activation of the mitochondrial apoptosis pathway and the Ca2+-CaMKII-dependent Akt/mTOR pathway. 相似文献
44.
Blood pressure regulation is impacted by a spinal cord injury (SCI) due to impaired descending sympathetic vascular control. Common blood pressure problems in the SCI population include persistently low blood pressure with bouts of orthostatic hypotension and autonomic dysreflexia, which are more prevalent in individuals with lesions above the sixth thoracic vertebral level; however, they may occur regardless of the neurological level of injury. Although blood pressure disorders adversely impact daily function and quality of life, most individuals with SCI do not acknowledge this association. Few pharmacological options have been rigorously tested for safety and efficacy to manage blood pressure disorders in the SCI population. Furthermore, clinical management of any one blood pressure disorder may adversely impact others, as such treatment is complicated and not often prioritized. 相似文献
45.
In the field of drug development, technology for producing human metabolites at a low cost is required. In this study, we explored the possibility of using prokaryotic water-soluble cytochrome P450 (CYP) to produce human metabolites. Streptomyces griseolus CYP105A1 metabolizes various non-steroidal anti-inflammatory drugs (NSAIDs), including diclofenac, mefenamic acid, flufenamic acid, tolfenamic acid, meclofenamic acid, and ibuprofen. CYP105A1 showed 4′-hydroxylation activity towards diclofenac, mefenamic acid, flufenamic acid, tolfenamic acid, and meclofenamic acid. It should be noted that this reaction specificity was similar to that of human CYP2C9. In the case of mefenamic acid, another metabolite, 3′-hydroxymethyl mefenamic acid, was detected as a major metabolite. Substitution of Arg at position 73 with Ala in CYP105A1 dramatically reduced the hydroxylation activity toward diclofenac, flufenamic acid, and ibuprofen, indicating that Arg73 is essential for the hydroxylation of these substrates. In contrast, substitution of Arg84 with Ala remarkably increased the hydroxylation activity towards diclofenac, mefenamic acid, and flufenamic acid. Recombinant Rhodococcus erythrocyte cells expressing the CYP105A1 variant R84A/M239A showed complete conversion of diclofenac into 4′-hydroxydiclofenac. These results suggest the usefulness of recombinant R. erythropolis cells expressing actinomycete CYP, such as CYP105A1, for the production of human drug metabolites. 相似文献
46.
47.
PurposeOptical coherence tomography angiography (OCTA) was utilized to examine changes in ocular surface squamous neoplasia (OSSN) vascular patterns over time in individuals treated with topical medical therapy.MethodsTen individuals with OSSN diagnosed by clinical examination and high resolution (HR)-optical coherence tomography (OCT) were recruited. All individuals received topical immuno- or chemotherapy. OCTA images were obtained and analyzed at three points: presentation, mid-treatment and tumor resolution. Tumor metrics including tumor area (TA), tumor volume (TV), tumor depth (TD), and total tumor density (TTD) were calculated. Vessel area density (VAD) was also quantified within the OSSN, the subepithelium under and adjacent to the OSSN and the subepithelium of the uninvolved, contralateral eye. Vascular network changes were also subjectively evaluated.ResultsTA, TV, TD and TTD all significantly decreased with time (p < 0.001). The mean VAD within the OSSN significantly decreased (p < 0.001) between visits (presentation: 26.52 ± 6.8%, mid-treatment: 7.19 ± 5.88%, tumor resolution: 0.11 ± 0.34%). The mean subepithelial VAD under the OSSN also decreased with time (23.22 ± 11.03%, 20.99 ± 5.99% and 19.58 ± 7.08%), and after resolution the sub-tumor VAD (19.58 ± 7.08%) was comparable to the subepithelial VAD in the contralateral eye (15.47 ± 4.37%, p > 0.05). The mean VAD in the subepithelium adjacent to the OSSN increased with treatment, then decreased significantly between mid-treatment and resolution (23.26 ± 4.54, 28.30 ± 7.43% and 21.68 ± 6.10%, p = 0.009). Qualitatively, the tumor subepithelial vascular network was complex and dense but with tumor resolution appeared less tortuous and similar to the uninvolved eye.ConclusionOCTA provided insight into the pathophysiology of tumor angiogenesis, showing decreased vascular density and normalization of vascular networks associated with tumor resolution. 相似文献
48.
49.
50.
Laura A. Huppert MD Ozge Gumusay MD Dame Idossa MD Hope S. Rugo MD 《CA: a cancer journal for clinicians》2023,73(5):480-515
Hormone receptor (HR)-positive and human epidermal growth factor receptor 2 (HER2)-negative breast cancer is defined by the presence of the estrogen receptor and/or the progesterone receptor and the absence of HER2 gene amplification. HR-positive/HER2-negative breast cancer accounts for 65%–70% of all breast cancers, and incidence increases with increasing age. Treatment varies by stage, and endocrine therapy is the mainstay of treatment in both early stage and late-stage disease. Combinations with cyclin-dependent kinase 4/6 inhibitors have reduced distant recurrence in the early stage setting and improved overall survival in the metastatic setting. Chemotherapy is used based on stage and tumor biology in the early stage setting and after endocrine resistance for advanced disease. New therapies, including novel endocrine agents and antibody-drug conjugates, are now changing the treatment landscape. With the availability of new treatment options, it is important to define the optimal sequence of treatment to maximize clinical benefit while minimizing toxicity. In this review, the authors first discuss the pathologic and molecular features of HR-positive/HER2-negative breast cancer and mechanisms of endocrine resistance. Then, they discuss current and emerging therapies for both early stage and metastatic HR-positive/HER2-negative breast cancer, including treatment algorithms based on current data. 相似文献