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   14801篇
  免费   957篇
  国内免费   308篇
耳鼻咽喉   378篇
儿科学   275篇
妇产科学   203篇
基础医学   2365篇
口腔科学   241篇
临床医学   1186篇
内科学   2918篇
皮肤病学   474篇
神经病学   1050篇
特种医学   945篇
外科学   2272篇
综合类   147篇
现状与发展   1篇
一般理论   2篇
预防医学   543篇
眼科学   487篇
药学   1191篇
中国医学   167篇
肿瘤学   1221篇
  2024年   10篇
  2023年   86篇
  2022年   326篇
  2021年   478篇
  2020年   238篇
  2019年   359篇
  2018年   466篇
  2017年   328篇
  2016年   499篇
  2015年   719篇
  2014年   860篇
  2013年   957篇
  2012年   1349篇
  2011年   1230篇
  2010年   785篇
  2009年   619篇
  2008年   873篇
  2007年   919篇
  2006年   804篇
  2005年   697篇
  2004年   529篇
  2003年   470篇
  2002年   453篇
  2001年   268篇
  2000年   212篇
  1999年   167篇
  1998年   97篇
  1997年   80篇
  1996年   69篇
  1995年   56篇
  1994年   44篇
  1993年   49篇
  1992年   105篇
  1991年   103篇
  1990年   87篇
  1989年   70篇
  1988年   74篇
  1987年   99篇
  1986年   66篇
  1985年   61篇
  1984年   38篇
  1983年   35篇
  1982年   27篇
  1981年   22篇
  1980年   14篇
  1979年   22篇
  1978年   36篇
  1976年   12篇
  1975年   11篇
  1974年   12篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Immunoprecipitation of radiolabeled polypeptides from complex mixtures of proteins was performed in polystyrene microtiter plates using staphylococcus protein A and various antibody preparations. The method is (1) rapid, (2) uses multichannel micropipettor technology, (3) handles large numbers of specimen easily, (4) requires very small volumes of antigen and antibody (5–50 μl), (5) provides replicates for statistical analysis and (6) allows recovery of precipitated proteins for direct SDS-PAGE analysis of precipitated proteins. We have shown it is useful as a test to screen large numbers of sera or to characterize monoclonal antibody-containing samples.  相似文献   
62.
PurposeOral adsorbents delay disease progression and improve uremic symptoms in patients with chronic kidney disease (CKD). DW-7202 is a newly developed oral adsorbent with high adsorptive selectivity for uremic toxins. We evaluated patient preference for and adherence to DW-7202 versus AST-120 therapy and compared treatment efficacy and safety in patients with pre-dialysis CKD.Materials and MethodsA seven-center, randomized, open-label, two-way crossover, active-controlled, phase IV clinical trial was conducted. Patients with stable CKD were randomly assigned to receive DW-7202 (capsule type) or AST-120 (granule type) for 12 weeks. The groups then switched to the other adsorbent and took it for the next 12 weeks. Patient preference was the primary outcome. Secondary outcomes included changes in estimated glomerular filtration rate (eGFR) and serum creatinine, cystatin C, and indoxyl sulfate (IS) levels.ResultsSignificantly more patients preferred DW-7202 than AST-120 (p<0.001). Patient adherence improved after switching from AST-120 to DW-7202; there was no apparent change in adherence after switching from DW-7202 to AST-120. Changes in eGFR and serum creatinine, cystatin C, and IS levels were not significantly different according to adsorbent type. There was also no significant difference in the incidences of adverse events during treatment with DW-7202 and AST-120.ConclusionDW-7202 can be considered as an alternative to AST-120 in patients who cannot tolerate or show poor adherence to granule type adsorbents. Further studies to evaluate factors affecting patient preferences and improved adherence are warranted (Clinical trial registration No. NCT02681952).  相似文献   
63.
An anaplastic large cell lymphoma that was negative for Epstein-Barr virus and positive for Ki-1 (CD30) presented as a polypoid scalp mass in a 56-year-old man 16 years after renal transplantation. The lymphoma was of the CD4+ cytotoxic T-cell lineage, and the tumor cells also expressed CD56. Despite reduction in the dose of immunosuppression and localized radiotherapy, the tumor had rapidly progressed to involve the soft tissue of the right hand. Systemic chemotherapy induced complete regression of the soft tissue lesion. This case illustrates that posttransplant primary cutaneous CD30+ anaplastic large cell lymphomas may assume an aggressive clinical course but can still be controlled by systemic chemotherapy.  相似文献   
64.
Previous molecular genetic studies of laryngeal squamous cell carcinoma (SCC)have shown certain chromosomal regions with recurring alterations. But studies of sequential molecular alterations and genetic progression model of laryngeal SCC have not been clearly defined. To identify the chromosomal alterations associated with the carcinogenesis of laryngeal SCC, we analyzed genomic DNA from microdissected squamous metaplasia, squamous dysplasia, invasive SCC, and metastatic carcinoma samples from 22 laryngeal SCC patients for loss of heterozygosity (LOH) at microsatellite loci. Ten microsatellite markers on chromosome 3p, 8p, 9p, and 17p were used. LOH at 9p21 was observed in the all stages including squamous metaplasia, squamous dysplasia, invasive SCC and metastatic carcinoma. LOH at 17p13.1, 3p25 and 3p14.2 was observed from the squamous dysplasia, invasive SCC and metastatic carcinoma. LOH at 8p21.3-p22 was observed mainly from the invasive SCC and metastatic carcinoma. The results suggest that 9p21 in the early event, 17p13.1, 3p25 and 3p14.2 in the intermediate event and 8p21.3- p22 in the late event may be involved in the laryngeal carcinogenesis.  相似文献   
65.
66.
Simultaneous turnover of normal and dysfunctional C1-inhibitor (C1-INH) was carried out in 10 normal subjects and 13 patients with rheumatoid arthritis as a measure of the in vivo activation of C1 and the contact activatable enzymes. In the first series of experiments, dysfunctional protein We was used in simultaneous turnover studies in five normal subjects and nine patients. The fractional catabolic rate of the dysfunctional C1-INH, We, (FCR(d)) was unchanged in both groups but the fractional catabolic rate of the normal C1-INH (FCR(n)) was faster in the patients compared to the controls, in particular patients with vasculitis. The enzyme-dependent catabolism defined as FCR(n-d) X concentration of C1-INH X plasma volume, was raised in the patient group, and correlated with disease activity score (r = 0.83, P less than 0.05). Neither FCR(n) nor FCR(d) was dependent on C1-INH concentration. The latter was higher in the patients (206 mg/l compared with 155 mg/l) indicating a very high synthetic rate in the patients (280.81 micrograms/kg/h compared with 179.77 micrograms/kg). In the second series of turnovers in six patients and five normal subjects, another dysfunctional C1-INH, at, was used. The FCR of C1-INH was slower than C1-INH (We) (1.88%/h compared with 2.7%/h). Enzyme-dependent catabolism of C1-INH in these patients were raised and also correlated with disease activity score (r = 0.82, P less than 0.05).  相似文献   
67.
Aspergilloma and invasive aspergillosis are important opportunistic infections caused by Aspergillus species, among which Aspergillus fumigatus is the most common species associated with human disease. We developed an enzyme-linked immunosorbent assay (ELISA)-based antibody assay with Afmp1p, a purified recombinant antigenic cell wall galactomannoprotein of A. fumigatus. Evaluation of the test with guinea pig sera against A. fumigatus and other pathogenic fungi indicated that this assay was specific for A. fumigatus. Clinical evaluation revealed that the assay was 100% sensitive for patients with aspergilloma and 33.3% sensitive for patients with invasive aspergillosis. No false-positive results were found for serum samples from 80 healthy blood donors, 6 patients with typhoid fever, 4 patients with melioidosis, 20 patients with penicilliosis marneffei, 5 patients with candidiasis, and 4 patients with cryptococcosis, indicating a high specificity of the test. Thus, this ELISA-based test for the detection of anti-Afmp1p antibody can be of significant value as a diagnostic for aspergillosis.  相似文献   
68.
Park SY  Kim HS  Hong EK  Kim WH 《Human pathology》2002,33(11):1078-1085
The expressions of cytokeratin (CK) 7 and 20 have been studied in various primary and metastatic carcinomas, and their determination may help distinguish the site of origin of metastatic carcinomas. However, little is known about the factors that determine variations in their expression patterns in primary gastric and colorectal carcinomas. We investigated the expressions of CK7 and CK20 in 289 cases of gastric carcinoma and 225 cases of colorectal carcinoma using a tissue microarray. To evaluate CK7 and CK20 expression patterns of ovarian metastases from gastric or colorectal carcinomas, 54 cases of metastatic carcinomas to the ovary were examined. It was found that 71% (207 of 289) of the gastric carcinomas stained positively for CK7, whereas only 9% (21 of 225) of the colorectal carcinomas proved to be CK7 positive, and that 41% (117 of 289) of the gastric carcinomas and 73% (165 of 225) of the colorectal carcinomas were CK20 positive. The proportion of CK7+/CK20- was highest in the gastric carcinomas at 46% (132 of 289), and was independent of the histologic classification of Lauren (46% of the intestinal type, 45% of the diffuse type). The CK7 and CK20 expression patterns were different in colorectal carcinomas according to histologic grade and location of the tumor. CK7-/CK20+ had the greatest proportion (68%) in colorectal carcinomas, and this was dependent on the tumor's histologic grade (75% of low-grade versus 52% of high-grade) and location (46% of right-sided versus 76% of left-sided). Moreover, 42% (18 of 43) of gastric carcinomas metastatic to the ovary were CK7+/CK20-, whereas 19% (8 of 43) were CK7-/CK20+. All colorectal cancers metastatic to the ovary were CK7-/CK20+, except 1 case that was CK7-/CK20-. In conclusion, the CK7 and CK20 expression patterns in primary gastric carcinomas vary considerably, and those in colorectal carcinomas are associated with histologic grade and tumor location. The CK7-/CK20+ expression pattern is specific for metastatic colorectal carcinomas to the ovary, but has low predictability for colorectal origin in metastatic ovarian carcinoma.  相似文献   
69.
70.
Loss of the cell adhesion molecule E-cadherin is suggested to promote tumor invasion and distant metastasis in tumor development. Recently, it has been proposed that E-cadherin function requires its linkage to the cytoskeleton through catenins. We evaluated the expression of E-cadherin and alpha-, beta-, gamma-catenins in tissues of human endometrial carcinoma, analyzed the patterns of cell adhesion molecules' expression in endometrial carcinoma and investigated the relationship between the statuses of cell adhesion molecules and various clinicopathological factors. This study investigated the immunohistochemical expression of E-cadherin and alpha-, beta-, gamma-catenins in 33 paraffin embedded formalin fixed tissues of endometrial carcinomas. Aberrant E-cadherin, and alpha-, beta-, gamma-catenin expression was observed in 33.3 (11 of 33), 27.3 (9 of 33), 18.2 (6 of 33), and 51.5 (17 of 33) % of the specimens, respectively. Statistically significant correlation was found between aberrant expression of E-cadherin and lymph node metastasis and cell types other than endometrioid adenocarcinoma. Aberrant pattern of gamma-catenin expression was also correlated with deep myometrial invasion. However, alpha-, and beta-catenin expression was not correlated with any clinicopathological parameters. Using the Kaplan-Meier method and log-rank comparison test, abnormal expression of E-cadherin was correlated closely with poor survival (p < 0.05), but cases with loss of both E-cadherin and catenin expression predicted even poorer survival than cases with only one or no aberrant expression in E-cadherin and catenins. We revealed aberrant expression of these cell adhesion molecules among patients with endometrial carcinoma. Aberrant expression of E-cadherin was correlated with lymph node metastasis and cell types other than endometrioid adenocarcinoma, while aberrant expression of gamma-catenin was related with deep myometrial invasion. The expression of E-cadherin might be a possible prognostic factor for endometrial cancer while the expression of catenins may help predict patient's survival.  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