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   286720篇
  免费   59728篇
  国内免费   16444篇
耳鼻咽喉   3356篇
儿科学   6288篇
妇产科学   2752篇
基础医学   40050篇
口腔科学   8751篇
临床医学   40527篇
内科学   53277篇
皮肤病学   9463篇
神经病学   23873篇
特种医学   10066篇
外国民族医学   127篇
外科学   34846篇
综合类   37841篇
现状与发展   63篇
一般理论   34篇
预防医学   18633篇
眼科学   7257篇
药学   27550篇
  170篇
中国医学   13584篇
肿瘤学   24384篇
  2024年   725篇
  2023年   3435篇
  2022年   8814篇
  2021年   12236篇
  2020年   13070篇
  2019年   17376篇
  2018年   17122篇
  2017年   17702篇
  2016年   17977篇
  2015年   21139篇
  2014年   23386篇
  2013年   22277篇
  2012年   19385篇
  2011年   20999篇
  2010年   19513篇
  2009年   13524篇
  2008年   12780篇
  2007年   11820篇
  2006年   11654篇
  2005年   11373篇
  2004年   7903篇
  2003年   7648篇
  2002年   6795篇
  2001年   6020篇
  2000年   6043篇
  1999年   5953篇
  1998年   3798篇
  1997年   3691篇
  1996年   2857篇
  1995年   2651篇
  1994年   2373篇
  1993年   1412篇
  1992年   1764篇
  1991年   1468篇
  1990年   1258篇
  1989年   1124篇
  1988年   927篇
  1987年   823篇
  1986年   687篇
  1985年   488篇
  1984年   270篇
  1983年   201篇
  1982年   127篇
  1981年   117篇
  1980年   73篇
  1979年   81篇
  1978年   7篇
  1977年   3篇
  1975年   5篇
  1973年   8篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
We aimed to evaluate the prospective association of vitamin B5 with all‐cause mortality and explore its potential modifiers in Chinese adults with hypertension. A nested, case‐control study was conducted in the China Stroke Primary Prevention Trial, including 505 deaths of all causes and 505 matched controls. The median follow‐up duration was 4.5 years. The primary outcome measure in this investigation was all‐cause mortality, which encompassed deaths for any reason. The mean plasma vitamin B5 concentration for cases (43.7 ng/mL) was higher than that in controls (40.9 ng/mL) (p = .001). When vitamin B5 was further assessed as quintiles, compared with the reference group (Q1: < 33.0 ng/mL), the risk of all‐cause mortality increased by 29% (OR = 1.29, 95% CI: 0.83‐2.01) in Q2, 22% (OR = 1.22, 95% CI: 0.77‐1.94) in Q3, 62% (OR = 1.62, 95% CI: 1.00‐2.62) in Q4, and 77% (OR = 1.77, 95% CI: 1.06‐2.95) in Q5. The trend test was significant (p = .022). When Q4‐Q5 were combined, a significant 41% increment (OR = 1.41, 95% CI: 1.03‐1.95) in all‐cause death risk was found compared with Q1‐Q3. The adverse effects were more pronounced in those with normal folate levels (p‐interaction = .019) and older people (p‐interaction = .037). This study suggests that higher baseline levels of plasma vitamin B5 are a risk factor for all‐cause mortality among Chinese patients with hypertension, especially among older adults and those with adequate folate levels. The findings, if confirmed, may inform novel clinical and nutritional guidelines and interventions to optimize vitamin B5 levels.  相似文献   
992.
Rationale:The spleen is an uncommon metastatic organ for malignant solid tumors because of its special anatomy and microenvironment. Isolated splenic metastasis of endometrial cancer is an extremely rare clinical event, with only 17 cases reported in literature.Patient concerns:We report the case of a 58-year-old woman with abdominal distension and nausea for 7 months who had undergone surgery and chemotherapy for endometrioid adenocarcinoma 12 years previously. A space-occupying lesion in the upper pole of the spleen was observed on an abdominal ultrasound.Diagnosis:The spleen was resected, and splenic metastasis of endometrial adenocarcinoma was histologically confirmed.Interventions:Splenectomy was performed, and no lymph nodes or other metastases were observed. The patient received postoperative chemotherapy with 6 cycles of docetaxel and carboplatin.Outcomes:The patient recovered well 11 months postoperatively, with no evidence of recurrence or metastatic disease.Lesson:Since the time interval between the diagnosis of primary endometrial cancer and splenic metastasis may be very long, it may be necessary to monitor the recurrence of endometrial cancer after primary treatment.  相似文献   
993.
Melatonin is an endogenous hormone with various biological functions and possesses anti‐tumor properties in multiple malignancies. Immune evasion is one of the most important hallmarks of head and neck squamous cell carcinoma (HNSCC) and is closely related to tumor progression. However, as an immune modulator under physiological conditions, the roles of melatonin in tumor immunity in HNSCC remains unclear. In this study, we found that the endogenous melatonin levels in patients with HNSCC were lower than those in patients with benign tumors in head and neck. Importantly, lower melatonin levels were related to lymph node metastasis among patients with HNSCC. Moreover, melatonin significantly suppressed programmed death‐ligand 1 (PD‐L1) expression and inhibited epithelial–mesenchymal transition (EMT) of HNSCC through the ERK1/2/FOSL1 pathway in vitro and in vivo. In SCC7/C3H syngeneic mouse models, anti‐programmed death‐1 (PD‐1) antibody combined with melatonin significantly inhibited tumor growth and modulated anti‐tumor immunity by increasing CD8+ T cell infiltration and decreasing the regulatory T cell (Treg) proportion in the tumor microenvironment. Taken together, melatonin inhibited EMT and downregulated PD‐L1 expression in HNSCC through the ERK1/2/FOSL1 pathway and exerted synergistic effects with anti‐PD‐1 antibody in vivo, which could provide promising strategies for HNSCC treatment.  相似文献   
994.
BackgroundAlpha-fetoprotein-producing gastric cancer (AFPGC) is a subtype of gastric cancer (GC) with more aggressive biological behavior. As a highly specific tight junction component exclusively present in gastric mucosa and gastric adenocarcinomas, claudin-18.2 (CLDN18.2) has become an emerging target in GC. In this study, we aimed to provide insight into AFPGC and investigate the expression and the clinical implications of CLDN18.2 in AFPGC.MethodsWe retrospectively collected 98 cases of AFPGC and reviewed their clinical, morphological, and immunohistochemical features. Another 356 patients with stage-matched conventional GC (cGC) were enrolled as a control group. We further surveyed CLDN18.2 expression by immunohistochemistry (IHC) in 51 AFPGC tissues and explained its association with the clinicopathological parameters of AFPGC.ResultsOur results showed that AFPGC was a unique GC type with elevated serum alpha-fetoprotein (AFP), which was a predictor of a worse prognosis. AFPGC showed typical morphological features and positive staining of at least 1 hepatocytic or enteroblastic marker. The expression rate of CLDN18.2 was low, with a positivity rate of 21.6%, which was much lower than that observed in cGC tissues (38.5%). A significant correlation was found between CLDN18.2 expression and the differentiation of AFPGC. CLDN18.2 expression was negatively correlated with the serum AFP level of AFPGC. We also found that AFPGC with a hepatoid type (HPT) component showed a significantly lower CLDN18.2 expression than those without.ConclusionsThis study demonstrated that CLDN18.2 was significantly decreased in AFPGC and was negatively correlated with the patient’s preoperative serum AFP level. The negative correlation between AFP and CLDN18.2 could be explained by retro-differentiation of AFPGC. Special treatment strategies might be needed for this unique tumor type.  相似文献   
995.
Rationale:Femtosecond laser-assisted cataract surgery (FLACS) has grown in popularity among ophthalmologists as a novel surgical technique. However, malignant glaucoma (MG) is a complication of FLACS. Herein, we report a case of MG following FLACS.Patient concerns:A 66-year-old woman presented with complaints of blurred vision in the right eye and a foreign body sensation in both eyes. Ophthalmological examinations showed that the corrected distance visual acuity was 20/50 and 20/25 in the right and left eyes, respectively. Without any topical anti-glaucoma medication, the intraocular pressure (IOP) was 20 mmHg in the right eye and 17 mmHg in the left eye. Slit-lamp examination of the right eye revealed a transparent cornea with a defect in the punctate overlying epithelium; the central anterior chamber depth was shallow the peripheral iris laser shot was visible, the pupil was normal, and the lens was mainly cortical opacified.Diagnoses:Based on the patient''s symptoms, examination results, and preliminary diagnoses, age-related cataract in the right eye, binocular post-antiglaucoma surgery, pseudophakicin in the left eye, and Sjogren syndrome were included.Interventions:FLACS was performed to facilitate anterior capsulotomy and segmentation of the nucleus in the right eye. MG occurred after the femtosecond procedure, and with the treatment of medicines combined with phacoemulsification, IOP was eventually normal without further antiglaucoma therapy.Outcomes:IOP was 16 mmHg on postoperative day 1. Ocular ultrasonography revealed no choroid detachment or hemorrhage in the right eye. Two weeks postoperatively, uncorrected visual acuity was 20/25, and IOP remained normal with no further antiglaucoma treatment on 1 month postoperatively.Conclusions:We describe the occurrence of MG after FLACS and illustrate that miosis and bubble formation after FLACS may be risk factors for MG during FLACS.  相似文献   
996.
The high-dose glucocorticosteroid (GC) treatment is the first choice for dermatomyositis complicated with interstitial lung disease (DM-ILD) but patients are resistant to the high-dose GC monotherapy. Besides, the high dose of GC, the secondary immunosuppressive agent(s) is necessary but there is controversy for the selection of immunosuppressive agent(s). The objectives of the study were to analyze the efficacy of different therapeutic options for DM-ILD to identify the optimal therapy. A total of 60 patients had received intravenous 1.0–2.0 mg/ kg/day prednisolone for DM-ILD. In severe conditions, patients had received oral 1 to 3 mg/day tacrolimus (TAC), 500 mg/ m2/month cyclophosphamide (CY), and/or 1 g/ day methylprednisolone pulse (TI cohort, n = 24). In severe conditions, patients had received 1 g/day methylprednisolone pulse and 2–3 mg/ kg/day cyclosporine A (CsA) and/or 500 mg/ m2/month CY (existing historical treatment; CT cohort, n = 36). Patients of the TI cohort did not receive CsA. Patients in the CT cohort were received CY in significantly fewer numbers than those of the TI cohort during treatment (P = .0112). A total of 11 (46%) patients from the TI cohort and 14 (39%) patients from the CT cohort were developed relapsed. At the end of the 30-months, higher numbers of patients of the TI cohort had an event(s) free survival than those of the CT cohort (7 (29%) vs 2 (6%), P = .0229). Also, higher numbers of patients of the TI cohort had survived irrespective of an event(s) than those of the CT cohort (21 (87%) vs 22 (61%), P = .0399). Patients of the TI cohort had developed herpes zoster (2 (8%)) and cytomegalovirus (4 (17%)) infections. Patients of the CT cohort developed renal dysfunction (10 (28%)). Hyperglycemia, hyperlipidemia, and fracture (GC-related toxicities) were also reported in both cohorts and these toxicities were fever in the TI cohort. The addition of TAC to high doses GC with CY is an ideal treatment for severe conditions of DM-ILD (Level of Evidence: III; Technical Efficacy Stage: 4).  相似文献   
997.
Zika virus (ZIKV) causes significant human diseases without specific therapy. Previously we found erythrosin B, an FDA-approved food additive, inhibited viral NS2B−NS3 interactions, leading to inhibition of ZIKV infection in cell culture. In this study, we performed pharmacokinetic and in vivo studies to demonstrate the efficacy of erythrosin B against ZIKV in 3D mini-brain organoid and mouse models. Our results showed that erythrosin B is very effective in abolishing ZIKV replication in the 3D organoid model. Although pharmacokinetics studies indicated that erythrosin B had a low absorption profile, mice challenged by a lethal dose of ZIKV showed a significantly improved survival rate upon oral administration of erythrosin B, compared to vehicle control. Limited structure−activity relationship studies indicated that most analogs of erythrosin B with modifications on the xanthene ring led to loss or reduction of inhibitory activities towards viral NS2B−NS3 interactions, protease activity and antiviral efficacy. In contrast, introducing chlorine substitutions on the isobenzofuran ring led to slightly increased activities, suggesting that the isobenzofuran ring is well tolerated for modifications. Cytotoxicity studies indicated that all derivatives are nontoxic to human cells. Overall, our studies demonstrated erythrosin B is an effective antiviral against ZIKV both in vitro and in vivo.KEY WORDS: Flavivirus, Zika virus, Dengue virus, Antiviral, Protease inhibitor, Erythrosin B  相似文献   
998.
BackgroundA growing number of studies have found a close association between thyroid hormones and thyrotrophin (TSH), and they also have prognostic significance in some cancer types; this study aimed to investigate the prognostic value of free triiodothyronine (fT3), free thyroxine (fT4), fT3/fT4, TSH, and their combination in patients with papillary thyroid carcinoma (PTC).MethodsThis study retrospectively analyzed the relevant data of 726 newly diagnosed PTC patients. Both univariate and multivariate analyses were used to predict the recurrence rate, and a risk score was established. In addition, with the use of a random survival forest, a random forest (RF) score was constructed. After calculating the area under the curve (AUC), the diagnostic efficacy of risk score, RF score, and four indicators was compared.ResultsfT3, fT4, fT3/fT4, and TSH were strongly associated with some invasive clinicopathological features and postoperative recurrence. Patients with high expression of fT4 and TSH have a high risk of recurrence. By contrast, patients with high expression of fT3 and fT3/fT4 have a low risk of recurrence. At the same time, the combined use of various indicators is more helpful for establishing an accurate diagnosis. By comparison, we found that the RF score was better than the risk score in terms of predicting the recurrence of PTC.ConclusionThe diagnostic accuracy of a combination of fT3, fT4, fT3/fT4, and TSH can help improve our clinical estimate of the risk of recurrent PTC, thus allowing the development of a more effective treatment plan for patients.  相似文献   
999.
BackgroundThe selective pressure imposed by chemotherapy creates a barrier to tumor eradication and an opportunity for metastasis and recurrence. As a newly discovered stemness marker of pancreatic ductal adenocarcinoma (PDAC), the impact of CD9 on tumor progression and patient''s prognosis remain controversial.MethodsA total of 179 and 211 PDAC patients who underwent surgical resection with or without neoadjuvant chemotherapy, respectively, were recruited for immunohistochemical analyses of CD9 expression in both tumor and stromal areas prior to statistical analyses to determine the prognostic impact and predictive accuracy of CD9.ResultsThe relationship between CD9 and prognostic indicators was not significant in the non‐neoadjuvant group. Nevertheless, CD9 expression in both tumor (T‐CD9) and stromal areas (S‐CD9) was significantly correlated with the clinicopathological features in the neoadjuvant group. High levels of T‐CD9 were significantly associated with worse OS (p = 0.005) and RFS (p = 0.007), while positive S‐CD9 showed the opposite results (OS: p = 0.024; RFS: p = 0.008). Cox regression analyses identified CD9 in both areas as an independent prognostic factor. The T&S‐CD9 risk‐level system was used to stratify patients with different survival levels. The combination of T&S‐CD9 risk level and TNM stage were accurate predictors of OS (C‐index: 0.676; AIC: 512.51) and RFS (C‐index: 0.680; AIC: 519.53). The calibration curve of the nomogram composed of the combined parameters showed excellent predictive consistency for 1‐year RFS. These results were verified using a validation cohort.ConclusionNeoadjuvant chemotherapy endows CD9 with a significant prognostic value that differs between tumor and stromal areas in patients with pancreatic cancer.  相似文献   
1000.
BackgroundThe spread of COVID‐19 worldwide caused by the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) has necessitated efficient, sensitive diagnostic methods to identify infected people. We report on the development of a rapid 15‐minute time‐resolved fluorescent (TRF) lateral flow immunochromatographic assay for the quantitative detection of the SARS‐CoV‐2 spike protein receptor‐binding domain (S1‐RBD).ObjectivesOur objective was to develop an efficient method of detecting SARS‐CoV‐2 within 15 min of sample collection.MethodsWe constructed and evaluated a portable, disposable lateral flow device, which detected the S1‐RBD protein directly in nasopharyngeal swab samples. The device emits a fluorescent signal in the presence of S1‐RBD, which can be captured by an automated TRF instrument.ResultsThe TRF lateral flow assay signal was linear from 0 to 20 ng/ml and demonstrated high accuracy and reproducibility. When evaluated with clinical nasopharyngeal swabs, the assay was performed at >80% sensitivity, >84% specificity, and > 82% accuracy for detection of the S1‐RBD antigen.ConclusionThe new S1‐RBD antigen test is a rapid (15 min), sensitive, and specific assay that requires minimal sample preparation. Critically, the assay correlated closely with PCR‐based methodology in nasopharyngeal swab samples, showing that the detected S1‐RBD antigen levels correlate with SARS‐CoV‐2 virus load. Therefore, the new TRF lateral flow test for S1‐RBD has potential application in point‐of‐care settings.  相似文献   
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